kernel/bpf/verifier.c

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 * Copyright (c) 2016 Facebook
 * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
 */
#include <uapi/linux/btf.h>
#include <linux/bpf-cgroup.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/bpf_verifier.h>
#include <linux/filter.h>
#include <net/netlink.h>
#include <linux/file.h>
#include <linux/vmalloc.h>
#include <linux/stringify.h>
#include <linux/bsearch.h>
#include <linux/sort.h>
#include <linux/perf_event.h>
#include <linux/ctype.h>
#include <linux/error-injection.h>
#include <linux/bpf_lsm.h>
#include <linux/btf_ids.h>
#include <linux/poison.h>
#include <linux/module.h>
#include <linux/cpumask.h>
#include <linux/bpf_mem_alloc.h>
#include <net/xdp.h>
#include <linux/trace_events.h>
#include <linux/kallsyms.h>

#include "disasm.h"

static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
	[_id] = & _name ## _verifier_ops,
#define BPF_MAP_TYPE(_id, _ops)
#define BPF_LINK_TYPE(_id, _name)
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE
};

struct bpf_mem_alloc bpf_global_percpu_ma;
static bool bpf_global_percpu_ma_set;

/* bpf_check() is a static code analyzer that walks eBPF program
 * instruction by instruction and updates register/stack state.
 * All paths of conditional branches are analyzed until 'bpf_exit' insn.
 *
 * The first pass is depth-first-search to check that the program is a DAG.
 * It rejects the following programs:
 * - larger than BPF_MAXINSNS insns
 * - if loop is present (detected via back-edge)
 * - unreachable insns exist (shouldn't be a forest. program = one function)
 * - out of bounds or malformed jumps
 * The second pass is all possible path descent from the 1st insn.
 * Since it's analyzing all paths through the program, the length of the
 * analysis is limited to 64k insn, which may be hit even if total number of
 * insn is less then 4K, but there are too many branches that change stack/regs.
 * Number of 'branches to be analyzed' is limited to 1k
 *
 * On entry to each instruction, each register has a type, and the instruction
 * changes the types of the registers depending on instruction semantics.
 * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
 * copied to R1.
 *
 * All registers are 64-bit.
 * R0 - return register
 * R1-R5 argument passing registers
 * R6-R9 callee saved registers
 * R10 - frame pointer read-only
 *
 * At the start of BPF program the register R1 contains a pointer to bpf_context
 * and has type PTR_TO_CTX.
 *
 * Verifier tracks arithmetic operations on pointers in case:
 *    BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
 *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
 * 1st insn copies R10 (which has FRAME_PTR) type into R1
 * and 2nd arithmetic instruction is pattern matched to recognize
 * that it wants to construct a pointer to some element within stack.
 * So after 2nd insn, the register R1 has type PTR_TO_STACK
 * (and -20 constant is saved for further stack bounds checking).
 * Meaning that this reg is a pointer to stack plus known immediate constant.
 *
 * Most of the time the registers have SCALAR_VALUE type, which
 * means the register has some value, but it's not a valid pointer.
 * (like pointer plus pointer becomes SCALAR_VALUE type)
 *
 * When verifier sees load or store instructions the type of base register
 * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK, PTR_TO_SOCKET. These are
 * four pointer types recognized by check_mem_access() function.
 *
 * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
 * and the range of [ptr, ptr + map's value_size) is accessible.
 *
 * registers used to pass values to function calls are checked against
 * function argument constraints.
 *
 * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
 * It means that the register type passed to this function must be
 * PTR_TO_STACK and it will be used inside the function as
 * 'pointer to map element key'
 *
 * For example the argument constraints for bpf_map_lookup_elem():
 *   .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
 *   .arg1_type = ARG_CONST_MAP_PTR,
 *   .arg2_type = ARG_PTR_TO_MAP_KEY,
 *
 * ret_type says that this function returns 'pointer to map elem value or null'
 * function expects 1st argument to be a const pointer to 'struct bpf_map' and
 * 2nd argument should be a pointer to stack, which will be used inside
 * the helper function as a pointer to map element key.
 *
 * On the kernel side the helper function looks like:
 * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 * {
 *    struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
 *    void *key = (void *) (unsigned long) r2;
 *    void *value;
 *
 *    here kernel can access 'key' and 'map' pointers safely, knowing that
 *    [key, key + map->key_size) bytes are valid and were initialized on
 *    the stack of eBPF program.
 * }
 *
 * Corresponding eBPF program may look like:
 *    BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),  // after this insn R2 type is FRAME_PTR
 *    BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
 *    BPF_LD_MAP_FD(BPF_REG_1, map_fd),      // after this insn R1 type is CONST_PTR_TO_MAP
 *    BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
 * here verifier looks at prototype of map_lookup_elem() and sees:
 * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
 * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
 *
 * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
 * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
 * and were initialized prior to this call.
 * If it's ok, then verifier allows this BPF_CALL insn and looks at
 * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
 * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
 * returns either pointer to map value or NULL.
 *
 * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
 * insn, the register holding that pointer in the true branch changes state to
 * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
 * branch. See check_cond_jmp_op().
 *
 * After the call R0 is set to return type of the function and registers R1-R5
 * are set to NOT_INIT to indicate that they are no longer readable.
 *
 * The following reference types represent a potential reference to a kernel
 * resource which, after first being allocated, must be checked and freed by
 * the BPF program:
 * - PTR_TO_SOCKET_OR_NULL, PTR_TO_SOCKET
 *
 * When the verifier sees a helper call return a reference type, it allocates a
 * pointer id for the reference and stores it in the current function state.
 * Similar to the way that PTR_TO_MAP_VALUE_OR_NULL is converted into
 * PTR_TO_MAP_VALUE, PTR_TO_SOCKET_OR_NULL becomes PTR_TO_SOCKET when the type
 * passes through a NULL-check conditional. For the branch wherein the state is
 * changed to CONST_IMM, the verifier releases the reference.
 *
 * For each helper function that allocates a reference, such as
 * bpf_sk_lookup_tcp(), there is a corresponding release function, such as
 * bpf_sk_release(). When a reference type passes into the release function,
 * the verifier also releases the reference. If any unchecked or unreleased
 * reference remains at the end of the program, the verifier rejects it.
 */

/* verifier_state + insn_idx are pushed to stack when branch is encountered */
struct bpf_verifier_stack_elem {
	/* verifier state is 'st'
	 * before processing instruction 'insn_idx'
	 * and after processing instruction 'prev_insn_idx'
	 */
	struct bpf_verifier_state st;
	int insn_idx;
	int prev_insn_idx;
	struct bpf_verifier_stack_elem *next;
	/* length of verifier log at the time this state was pushed on stack */
	u32 log_pos;
};

#define BPF_COMPLEXITY_LIMIT_JMP_SEQ	8192
#define BPF_COMPLEXITY_LIMIT_STATES	64

#define BPF_MAP_KEY_POISON	(1ULL << 63)
#define BPF_MAP_KEY_SEEN	(1ULL << 62)

#define BPF_GLOBAL_PERCPU_MA_MAX_SIZE  512

static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx);
static int release_reference(struct bpf_verifier_env *env, int ref_obj_id);
static void invalidate_non_owning_refs(struct bpf_verifier_env *env);
static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env);
static int ref_set_non_owning(struct bpf_verifier_env *env,
			      struct bpf_reg_state *reg);
static void specialize_kfunc(struct bpf_verifier_env *env,
			     u32 func_id, u16 offset, unsigned long *addr);
static bool is_trusted_reg(const struct bpf_reg_state *reg);

static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux)
{
	return aux->map_ptr_state.poison;
}

static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux)
{
	return aux->map_ptr_state.unpriv;
}

static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux,
			      struct bpf_map *map,
			      bool unpriv, bool poison)
{
	unpriv |= bpf_map_ptr_unpriv(aux);
	aux->map_ptr_state.unpriv = unpriv;
	aux->map_ptr_state.poison = poison;
	aux->map_ptr_state.map_ptr = map;
}

static bool bpf_map_key_poisoned(const struct bpf_insn_aux_data *aux)
{
	return aux->map_key_state & BPF_MAP_KEY_POISON;
}

static bool bpf_map_key_unseen(const struct bpf_insn_aux_data *aux)
{
	return !(aux->map_key_state & BPF_MAP_KEY_SEEN);
}

static u64 bpf_map_key_immediate(const struct bpf_insn_aux_data *aux)
{
	return aux->map_key_state & ~(BPF_MAP_KEY_SEEN | BPF_MAP_KEY_POISON);
}

static void bpf_map_key_store(struct bpf_insn_aux_data *aux, u64 state)
{
	bool poisoned = bpf_map_key_poisoned(aux);

	aux->map_key_state = state | BPF_MAP_KEY_SEEN |
			     (poisoned ? BPF_MAP_KEY_POISON : 0ULL);
}

static bool bpf_helper_call(const struct bpf_insn *insn)
{
	return insn->code == (BPF_JMP | BPF_CALL) &&
	       insn->src_reg == 0;
}

static bool bpf_pseudo_call(const struct bpf_insn *insn)
{
	return insn->code == (BPF_JMP | BPF_CALL) &&
	       insn->src_reg == BPF_PSEUDO_CALL;
}

static bool bpf_pseudo_kfunc_call(const struct bpf_insn *insn)
{
	return insn->code == (BPF_JMP | BPF_CALL) &&
	       insn->src_reg == BPF_PSEUDO_KFUNC_CALL;
}

struct bpf_call_arg_meta {
	struct bpf_map *map_ptr;
	bool raw_mode;
	bool pkt_access;
	u8 release_regno;
	int regno;
	int access_size;
	int mem_size;
	u64 msize_max_value;
	int ref_obj_id;
	int dynptr_id;
	int map_uid;
	int func_id;
	struct btf *btf;
	u32 btf_id;
	struct btf *ret_btf;
	u32 ret_btf_id;
	u32 subprogno;
	struct btf_field *kptr_field;
};

struct bpf_kfunc_call_arg_meta {
	/* In parameters */
	struct btf *btf;
	u32 func_id;
	u32 kfunc_flags;
	const struct btf_type *func_proto;
	const char *func_name;
	/* Out parameters */
	u32 ref_obj_id;
	u8 release_regno;
	bool r0_rdonly;
	u32 ret_btf_id;
	u64 r0_size;
	u32 subprogno;
	struct {
		u64 value;
		bool found;
	} arg_constant;

	/* arg_{btf,btf_id,owning_ref} are used by kfunc-specific handling,
	 * generally to pass info about user-defined local kptr types to later
	 * verification logic
	 *   bpf_obj_drop/bpf_percpu_obj_drop
	 *     Record the local kptr type to be drop'd
	 *   bpf_refcount_acquire (via KF_ARG_PTR_TO_REFCOUNTED_KPTR arg type)
	 *     Record the local kptr type to be refcount_incr'd and use
	 *     arg_owning_ref to determine whether refcount_acquire should be
	 *     fallible
	 */
	struct btf *arg_btf;
	u32 arg_btf_id;
	bool arg_owning_ref;

	struct {
		struct btf_field *field;
	} arg_list_head;
	struct {
		struct btf_field *field;
	} arg_rbtree_root;
	struct {
		enum bpf_dynptr_type type;
		u32 id;
		u32 ref_obj_id;
	} initialized_dynptr;
	struct {
		u8 spi;
		u8 frameno;
	} iter;
	struct {
		struct bpf_map *ptr;
		int uid;
	} map;
	u64 mem_size;
};

struct btf *btf_vmlinux;

static const char *btf_type_name(const struct btf *btf, u32 id)
{
	return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off);
}

static DEFINE_MUTEX(bpf_verifier_lock);
static DEFINE_MUTEX(bpf_percpu_ma_lock);

__printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
{
	struct bpf_verifier_env *env = private_data;
	va_list args;

	if (!bpf_verifier_log_needed(&env->log))
		return;

	va_start(args, fmt);
	bpf_verifier_vlog(&env->log, fmt, args);
	va_end(args);
}

static void verbose_invalid_scalar(struct bpf_verifier_env *env,
				   struct bpf_reg_state *reg,
				   struct bpf_retval_range range, const char *ctx,
				   const char *reg_name)
{
	bool unknown = true;

	verbose(env, "%s the register %s has", ctx, reg_name);
	if (reg->smin_value > S64_MIN) {
		verbose(env, " smin=%lld", reg->smin_value);
		unknown = false;
	}
	if (reg->smax_value < S64_MAX) {
		verbose(env, " smax=%lld", reg->smax_value);
		unknown = false;
	}
	if (unknown)
		verbose(env, " unknown scalar value");
	verbose(env, " should have been in [%d, %d]\n", range.minval, range.maxval);
}

static bool reg_not_null(const struct bpf_reg_state *reg)
{
	enum bpf_reg_type type;

	type = reg->type;
	if (type_may_be_null(type))
		return false;

	type = base_type(type);
	return type == PTR_TO_SOCKET ||
		type == PTR_TO_TCP_SOCK ||
		type == PTR_TO_MAP_VALUE ||
		type == PTR_TO_MAP_KEY ||
		type == PTR_TO_SOCK_COMMON ||
		(type == PTR_TO_BTF_ID && is_trusted_reg(reg)) ||
		type == PTR_TO_MEM;
}

static struct btf_record *reg_btf_record(const struct bpf_reg_state *reg)
{
	struct btf_record *rec = NULL;
	struct btf_struct_meta *meta;

	if (reg->type == PTR_TO_MAP_VALUE) {
		rec = reg->map_ptr->record;
	} else if (type_is_ptr_alloc_obj(reg->type)) {
		meta = btf_find_struct_meta(reg->btf, reg->btf_id);
		if (meta)
			rec = meta->record;
	}
	return rec;
}

static bool subprog_is_global(const struct bpf_verifier_env *env, int subprog)
{
	struct bpf_func_info_aux *aux = env->prog->aux->func_info_aux;

	return aux && aux[subprog].linkage == BTF_FUNC_GLOBAL;
}

static const char *subprog_name(const struct bpf_verifier_env *env, int subprog)
{
	struct bpf_func_info *info;

	if (!env->prog->aux->func_info)
		return "";

	info = &env->prog->aux->func_info[subprog];
	return btf_type_name(env->prog->aux->btf, info->type_id);
}

static void mark_subprog_exc_cb(struct bpf_verifier_env *env, int subprog)
{
	struct bpf_subprog_info *info = subprog_info(env, subprog);

	info->is_cb = true;
	info->is_async_cb = true;
	info->is_exception_cb = true;
}

static bool subprog_is_exc_cb(struct bpf_verifier_env *env, int subprog)
{
	return subprog_info(env, subprog)->is_exception_cb;
}

static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
{
	return btf_record_has_field(reg_btf_record(reg), BPF_SPIN_LOCK);
}

static bool type_is_rdonly_mem(u32 type)
{
	return type & MEM_RDONLY;
}

static bool is_acquire_function(enum bpf_func_id func_id,
				const struct bpf_map *map)
{
	enum bpf_map_type map_type = map ? map->map_type : BPF_MAP_TYPE_UNSPEC;

	if (func_id == BPF_FUNC_sk_lookup_tcp ||
	    func_id == BPF_FUNC_sk_lookup_udp ||
	    func_id == BPF_FUNC_skc_lookup_tcp ||
	    func_id == BPF_FUNC_ringbuf_reserve ||
	    func_id == BPF_FUNC_kptr_xchg)
		return true;

	if (func_id == BPF_FUNC_map_lookup_elem &&
	    (map_type == BPF_MAP_TYPE_SOCKMAP ||
	     map_type == BPF_MAP_TYPE_SOCKHASH))
		return true;

	return false;
}

static bool is_ptr_cast_function(enum bpf_func_id func_id)
{
	return func_id == BPF_FUNC_tcp_sock ||
		func_id == BPF_FUNC_sk_fullsock ||
		func_id == BPF_FUNC_skc_to_tcp_sock ||
		func_id == BPF_FUNC_skc_to_tcp6_sock ||
		func_id == BPF_FUNC_skc_to_udp6_sock ||
		func_id == BPF_FUNC_skc_to_mptcp_sock ||
		func_id == BPF_FUNC_skc_to_tcp_timewait_sock ||
		func_id == BPF_FUNC_skc_to_tcp_request_sock;
}

static bool is_dynptr_ref_function(enum bpf_func_id func_id)
{
	return func_id == BPF_FUNC_dynptr_data;
}

static bool is_sync_callback_calling_kfunc(u32 btf_id);
static bool is_async_callback_calling_kfunc(u32 btf_id);
static bool is_callback_calling_kfunc(u32 btf_id);
static bool is_bpf_throw_kfunc(struct bpf_insn *insn);

static bool is_bpf_wq_set_callback_impl_kfunc(u32 btf_id);

static bool is_sync_callback_calling_function(enum bpf_func_id func_id)
{
	return func_id == BPF_FUNC_for_each_map_elem ||
	       func_id == BPF_FUNC_find_vma ||
	       func_id == BPF_FUNC_loop ||
	       func_id == BPF_FUNC_user_ringbuf_drain;
}

static bool is_async_callback_calling_function(enum bpf_func_id func_id)
{
	return func_id == BPF_FUNC_timer_set_callback;
}

static bool is_callback_calling_function(enum bpf_func_id func_id)
{
	return is_sync_callback_calling_function(func_id) ||
	       is_async_callback_calling_function(func_id);
}

static bool is_sync_callback_calling_insn(struct bpf_insn *insn)
{
	return (bpf_helper_call(insn) && is_sync_callback_calling_function(insn->imm)) ||
	       (bpf_pseudo_kfunc_call(insn) && is_sync_callback_calling_kfunc(insn->imm));
}

static bool is_async_callback_calling_insn(struct bpf_insn *insn)
{
	return (bpf_helper_call(insn) && is_async_callback_calling_function(insn->imm)) ||
	       (bpf_pseudo_kfunc_call(insn) && is_async_callback_calling_kfunc(insn->imm));
}

static bool is_may_goto_insn(struct bpf_insn *insn)
{
	return insn->code == (BPF_JMP | BPF_JCOND) && insn->src_reg == BPF_MAY_GOTO;
}

static bool is_may_goto_insn_at(struct bpf_verifier_env *env, int insn_idx)
{
	return is_may_goto_insn(&env->prog->insnsi[insn_idx]);
}

static bool is_storage_get_function(enum bpf_func_id func_id)
{
	return func_id == BPF_FUNC_sk_storage_get ||
	       func_id == BPF_FUNC_inode_storage_get ||
	       func_id == BPF_FUNC_task_storage_get ||
	       func_id == BPF_FUNC_cgrp_storage_get;
}

static bool helper_multiple_ref_obj_use(enum bpf_func_id func_id,
					const struct bpf_map *map)
{
	int ref_obj_uses = 0;

	if (is_ptr_cast_function(func_id))
		ref_obj_uses++;
	if (is_acquire_function(func_id, map))
		ref_obj_uses++;
	if (is_dynptr_ref_function(func_id))
		ref_obj_uses++;

	return ref_obj_uses > 1;
}

static bool is_cmpxchg_insn(const struct bpf_insn *insn)
{
	return BPF_CLASS(insn->code) == BPF_STX &&
	       BPF_MODE(insn->code) == BPF_ATOMIC &&
	       insn->imm == BPF_CMPXCHG;
}

static int __get_spi(s32 off)
{
	return (-off - 1) / BPF_REG_SIZE;
}

static struct bpf_func_state *func(struct bpf_verifier_env *env,
				   const struct bpf_reg_state *reg)
{
	struct bpf_verifier_state *cur = env->cur_state;

	return cur->frame[reg->frameno];
}

static bool is_spi_bounds_valid(struct bpf_func_state *state, int spi, int nr_slots)
{
       int allocated_slots = state->allocated_stack / BPF_REG_SIZE;

       /* We need to check that slots between [spi - nr_slots + 1, spi] are
	* within [0, allocated_stack).
	*
	* Please note that the spi grows downwards. For example, a dynptr
	* takes the size of two stack slots; the first slot will be at
	* spi and the second slot will be at spi - 1.
	*/
       return spi - nr_slots + 1 >= 0 && spi < allocated_slots;
}

static int stack_slot_obj_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
			          const char *obj_kind, int nr_slots)
{
	int off, spi;

	if (!tnum_is_const(reg->var_off)) {
		verbose(env, "%s has to be at a constant offset\n", obj_kind);
		return -EINVAL;
	}

	off = reg->off + reg->var_off.value;
	if (off % BPF_REG_SIZE) {
		verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off);
		return -EINVAL;
	}

	spi = __get_spi(off);
	if (spi + 1 < nr_slots) {
		verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off);
		return -EINVAL;
	}

	if (!is_spi_bounds_valid(func(env, reg), spi, nr_slots))
		return -ERANGE;
	return spi;
}

static int dynptr_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
	return stack_slot_obj_get_spi(env, reg, "dynptr", BPF_DYNPTR_NR_SLOTS);
}

static int iter_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int nr_slots)
{
	return stack_slot_obj_get_spi(env, reg, "iter", nr_slots);
}

static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type)
{
	switch (arg_type & DYNPTR_TYPE_FLAG_MASK) {
	case DYNPTR_TYPE_LOCAL:
		return BPF_DYNPTR_TYPE_LOCAL;
	case DYNPTR_TYPE_RINGBUF:
		return BPF_DYNPTR_TYPE_RINGBUF;
	case DYNPTR_TYPE_SKB:
		return BPF_DYNPTR_TYPE_SKB;
	case DYNPTR_TYPE_XDP:
		return BPF_DYNPTR_TYPE_XDP;
	default:
		return BPF_DYNPTR_TYPE_INVALID;
	}
}

static enum bpf_type_flag get_dynptr_type_flag(enum bpf_dynptr_type type)
{
	switch (type) {
	case BPF_DYNPTR_TYPE_LOCAL:
		return DYNPTR_TYPE_LOCAL;
	case BPF_DYNPTR_TYPE_RINGBUF:
		return DYNPTR_TYPE_RINGBUF;
	case BPF_DYNPTR_TYPE_SKB:
		return DYNPTR_TYPE_SKB;
	case BPF_DYNPTR_TYPE_XDP:
		return DYNPTR_TYPE_XDP;
	default:
		return 0;
	}
}

static bool dynptr_type_refcounted(enum bpf_dynptr_type type)
{
	return type == BPF_DYNPTR_TYPE_RINGBUF;
}

static void __mark_dynptr_reg(struct bpf_reg_state *reg,
			      enum bpf_dynptr_type type,
			      bool first_slot, int dynptr_id);

static void __mark_reg_not_init(const struct bpf_verifier_env *env,
				struct bpf_reg_state *reg);

static void mark_dynptr_stack_regs(struct bpf_verifier_env *env,
				   struct bpf_reg_state *sreg1,
				   struct bpf_reg_state *sreg2,
				   enum bpf_dynptr_type type)
{
	int id = ++env->id_gen;

	__mark_dynptr_reg(sreg1, type, true, id);
	__mark_dynptr_reg(sreg2, type, false, id);
}

static void mark_dynptr_cb_reg(struct bpf_verifier_env *env,
			       struct bpf_reg_state *reg,
			       enum bpf_dynptr_type type)
{
	__mark_dynptr_reg(reg, type, true, ++env->id_gen);
}

static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env,
				        struct bpf_func_state *state, int spi);

static int mark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
				   enum bpf_arg_type arg_type, int insn_idx, int clone_ref_obj_id)
{
	struct bpf_func_state *state = func(env, reg);
	enum bpf_dynptr_type type;
	int spi, i, err;

	spi = dynptr_get_spi(env, reg);
	if (spi < 0)
		return spi;

	/* We cannot assume both spi and spi - 1 belong to the same dynptr,
	 * hence we need to call destroy_if_dynptr_stack_slot twice for both,
	 * to ensure that for the following example:
	 *	[d1][d1][d2][d2]
	 * spi    3   2   1   0
	 * So marking spi = 2 should lead to destruction of both d1 and d2. In
	 * case they do belong to same dynptr, second call won't see slot_type
	 * as STACK_DYNPTR and will simply skip destruction.
	 */
	err = destroy_if_dynptr_stack_slot(env, state, spi);
	if (err)
		return err;
	err = destroy_if_dynptr_stack_slot(env, state, spi - 1);
	if (err)
		return err;

	for (i = 0; i < BPF_REG_SIZE; i++) {
		state->stack[spi].slot_type[i] = STACK_DYNPTR;
		state->stack[spi - 1].slot_type[i] = STACK_DYNPTR;
	}

	type = arg_to_dynptr_type(arg_type);
	if (type == BPF_DYNPTR_TYPE_INVALID)
		return -EINVAL;

	mark_dynptr_stack_regs(env, &state->stack[spi].spilled_ptr,
			       &state->stack[spi - 1].spilled_ptr, type);

	if (dynptr_type_refcounted(type)) {
		/* The id is used to track proper releasing */
		int id;

		if (clone_ref_obj_id)
			id = clone_ref_obj_id;
		else
			id = acquire_reference_state(env, insn_idx);

		if (id < 0)
			return id;

		state->stack[spi].spilled_ptr.ref_obj_id = id;
		state->stack[spi - 1].spilled_ptr.ref_obj_id = id;
	}

	state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
	state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN;

	return 0;
}

static void invalidate_dynptr(struct bpf_verifier_env *env, struct bpf_func_state *state, int spi)
{
	int i;

	for (i = 0; i < BPF_REG_SIZE; i++) {
		state->stack[spi].slot_type[i] = STACK_INVALID;
		state->stack[spi - 1].slot_type[i] = STACK_INVALID;
	}

	__mark_reg_not_init(env, &state->stack[spi].spilled_ptr);
	__mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr);

	/* Why do we need to set REG_LIVE_WRITTEN for STACK_INVALID slot?
	 *
	 * While we don't allow reading STACK_INVALID, it is still possible to
	 * do <8 byte writes marking some but not all slots as STACK_MISC. Then,
	 * helpers or insns can do partial read of that part without failing,
	 * but check_stack_range_initialized, check_stack_read_var_off, and
	 * check_stack_read_fixed_off will do mark_reg_read for all 8-bytes of
	 * the slot conservatively. Hence we need to prevent those liveness
	 * marking walks.
	 *
	 * This was not a problem before because STACK_INVALID is only set by
	 * default (where the default reg state has its reg->parent as NULL), or
	 * in clean_live_states after REG_LIVE_DONE (at which point
	 * mark_reg_read won't walk reg->parent chain), but not randomly during
	 * verifier state exploration (like we did above). Hence, for our case
	 * parentage chain will still be live (i.e. reg->parent may be
	 * non-NULL), while earlier reg->parent was NULL, so we need
	 * REG_LIVE_WRITTEN to screen off read marker propagation when it is
	 * done later on reads or by mark_dynptr_read as well to unnecessary
	 * mark registers in verifier state.
	 */
	state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
	state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN;
}

static int unmark_stack_slots_dynptr(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
	struct bpf_func_state *state = func(env, reg);
	int spi, ref_obj_id, i;

	spi = dynptr_get_spi(env, reg);
	if (spi < 0)
		return spi;

	if (!dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) {
		invalidate_dynptr(env, state, spi);
		return 0;
	}

	ref_obj_id = state->stack[spi].spilled_ptr.ref_obj_id;

	/* If the dynptr has a ref_obj_id, then we need to invalidate
	 * two things:
	 *
	 * 1) Any dynptrs with a matching ref_obj_id (clones)
	 * 2) Any slices derived from this dynptr.
	 */

	/* Invalidate any slices associated with this dynptr */
	WARN_ON_ONCE(release_reference(env, ref_obj_id));

	/* Invalidate any dynptr clones */
	for (i = 1; i < state->allocated_stack / BPF_REG_SIZE; i++) {
		if (state->stack[i].spilled_ptr.ref_obj_id != ref_obj_id)
			continue;

		/* it should always be the case that if the ref obj id
		 * matches then the stack slot also belongs to a
		 * dynptr
		 */
		if (state->stack[i].slot_type[0] != STACK_DYNPTR) {
			verbose(env, "verifier internal error: misconfigured ref_obj_id\n");
			return -EFAULT;
		}
		if (state->stack[i].spilled_ptr.dynptr.first_slot)
			invalidate_dynptr(env, state, i);
	}

	return 0;
}

static void __mark_reg_unknown(const struct bpf_verifier_env *env,
			       struct bpf_reg_state *reg);

static void mark_reg_invalid(const struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
	if (!env->allow_ptr_leaks)
		__mark_reg_not_init(env, reg);
	else
		__mark_reg_unknown(env, reg);
}

static int destroy_if_dynptr_stack_slot(struct bpf_verifier_env *env,
				        struct bpf_func_state *state, int spi)
{
	struct bpf_func_state *fstate;
	struct bpf_reg_state *dreg;
	int i, dynptr_id;

	/* We always ensure that STACK_DYNPTR is never set partially,
	 * hence just checking for slot_type[0] is enough. This is
	 * different for STACK_SPILL, where it may be only set for
	 * 1 byte, so code has to use is_spilled_reg.
	 */
	if (state->stack[spi].slot_type[0] != STACK_DYNPTR)
		return 0;

	/* Reposition spi to first slot */
	if (!state->stack[spi].spilled_ptr.dynptr.first_slot)
		spi = spi + 1;

	if (dynptr_type_refcounted(state->stack[spi].spilled_ptr.dynptr.type)) {
		verbose(env, "cannot overwrite referenced dynptr\n");
		return -EINVAL;
	}

	mark_stack_slot_scratched(env, spi);
	mark_stack_slot_scratched(env, spi - 1);

	/* Writing partially to one dynptr stack slot destroys both. */
	for (i = 0; i < BPF_REG_SIZE; i++) {
		state->stack[spi].slot_type[i] = STACK_INVALID;
		state->stack[spi - 1].slot_type[i] = STACK_INVALID;
	}

	dynptr_id = state->stack[spi].spilled_ptr.id;
	/* Invalidate any slices associated with this dynptr */
	bpf_for_each_reg_in_vstate(env->cur_state, fstate, dreg, ({
		/* Dynptr slices are only PTR_TO_MEM_OR_NULL and PTR_TO_MEM */
		if (dreg->type != (PTR_TO_MEM | PTR_MAYBE_NULL) && dreg->type != PTR_TO_MEM)
			continue;
		if (dreg->dynptr_id == dynptr_id)
			mark_reg_invalid(env, dreg);
	}));

	/* Do not release reference state, we are destroying dynptr on stack,
	 * not using some helper to release it. Just reset register.
	 */
	__mark_reg_not_init(env, &state->stack[spi].spilled_ptr);
	__mark_reg_not_init(env, &state->stack[spi - 1].spilled_ptr);

	/* Same reason as unmark_stack_slots_dynptr above */
	state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
	state->stack[spi - 1].spilled_ptr.live |= REG_LIVE_WRITTEN;

	return 0;
}

static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
	int spi;

	if (reg->type == CONST_PTR_TO_DYNPTR)
		return false;

	spi = dynptr_get_spi(env, reg);

	/* -ERANGE (i.e. spi not falling into allocated stack slots) isn't an
	 * error because this just means the stack state hasn't been updated yet.
	 * We will do check_mem_access to check and update stack bounds later.
	 */
	if (spi < 0 && spi != -ERANGE)
		return false;

	/* We don't need to check if the stack slots are marked by previous
	 * dynptr initializations because we allow overwriting existing unreferenced
	 * STACK_DYNPTR slots, see mark_stack_slots_dynptr which calls
	 * destroy_if_dynptr_stack_slot to ensure dynptr objects at the slots we are
	 * touching are completely destructed before we reinitialize them for a new
	 * one. For referenced ones, destroy_if_dynptr_stack_slot returns an error early
	 * instead of delaying it until the end where the user will get "Unreleased
	 * reference" error.
	 */
	return true;
}

static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
	struct bpf_func_state *state = func(env, reg);
	int i, spi;

	/* This already represents first slot of initialized bpf_dynptr.
	 *
	 * CONST_PTR_TO_DYNPTR already has fixed and var_off as 0 due to
	 * check_func_arg_reg_off's logic, so we don't need to check its
	 * offset and alignment.
	 */
	if (reg->type == CONST_PTR_TO_DYNPTR)
		return true;

	spi = dynptr_get_spi(env, reg);
	if (spi < 0)
		return false;
	if (!state->stack[spi].spilled_ptr.dynptr.first_slot)
		return false;

	for (i = 0; i < BPF_REG_SIZE; i++) {
		if (state->stack[spi].slot_type[i] != STACK_DYNPTR ||
		    state->stack[spi - 1].slot_type[i] != STACK_DYNPTR)
			return false;
	}

	return true;
}

static bool is_dynptr_type_expected(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
				    enum bpf_arg_type arg_type)
{
	struct bpf_func_state *state = func(env, reg);
	enum bpf_dynptr_type dynptr_type;
	int spi;

	/* ARG_PTR_TO_DYNPTR takes any type of dynptr */
	if (arg_type == ARG_PTR_TO_DYNPTR)
		return true;

	dynptr_type = arg_to_dynptr_type(arg_type);
	if (reg->type == CONST_PTR_TO_DYNPTR) {
		return reg->dynptr.type == dynptr_type;
	} else {
		spi = dynptr_get_spi(env, reg);
		if (spi < 0)
			return false;
		return state->stack[spi].spilled_ptr.dynptr.type == dynptr_type;
	}
}

static void __mark_reg_known_zero(struct bpf_reg_state *reg);

static bool in_rcu_cs(struct bpf_verifier_env *env);

static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta);

static int mark_stack_slots_iter(struct bpf_verifier_env *env,
				 struct bpf_kfunc_call_arg_meta *meta,
				 struct bpf_reg_state *reg, int insn_idx,
				 struct btf *btf, u32 btf_id, int nr_slots)
{
	struct bpf_func_state *state = func(env, reg);
	int spi, i, j, id;

	spi = iter_get_spi(env, reg, nr_slots);
	if (spi < 0)
		return spi;

	id = acquire_reference_state(env, insn_idx);
	if (id < 0)
		return id;

	for (i = 0; i < nr_slots; i++) {
		struct bpf_stack_state *slot = &state->stack[spi - i];
		struct bpf_reg_state *st = &slot->spilled_ptr;

		__mark_reg_known_zero(st);
		st->type = PTR_TO_STACK; /* we don't have dedicated reg type */
		if (is_kfunc_rcu_protected(meta)) {
			if (in_rcu_cs(env))
				st->type |= MEM_RCU;
			else
				st->type |= PTR_UNTRUSTED;
		}
		st->live |= REG_LIVE_WRITTEN;
		st->ref_obj_id = i == 0 ? id : 0;
		st->iter.btf = btf;
		st->iter.btf_id = btf_id;
		st->iter.state = BPF_ITER_STATE_ACTIVE;
		st->iter.depth = 0;

		for (j = 0; j < BPF_REG_SIZE; j++)
			slot->slot_type[j] = STACK_ITER;

		mark_stack_slot_scratched(env, spi - i);
	}

	return 0;
}

static int unmark_stack_slots_iter(struct bpf_verifier_env *env,
				   struct bpf_reg_state *reg, int nr_slots)
{
	struct bpf_func_state *state = func(env, reg);
	int spi, i, j;

	spi = iter_get_spi(env, reg, nr_slots);
	if (spi < 0)
		return spi;

	for (i = 0; i < nr_slots; i++) {
		struct bpf_stack_state *slot = &state->stack[spi - i];
		struct bpf_reg_state *st = &slot->spilled_ptr;

		if (i == 0)
			WARN_ON_ONCE(release_reference(env, st->ref_obj_id));

		__mark_reg_not_init(env, st);

		/* see unmark_stack_slots_dynptr() for why we need to set REG_LIVE_WRITTEN */
		st->live |= REG_LIVE_WRITTEN;

		for (j = 0; j < BPF_REG_SIZE; j++)
			slot->slot_type[j] = STACK_INVALID;

		mark_stack_slot_scratched(env, spi - i);
	}

	return 0;
}

static bool is_iter_reg_valid_uninit(struct bpf_verifier_env *env,
				     struct bpf_reg_state *reg, int nr_slots)
{
	struct bpf_func_state *state = func(env, reg);
	int spi, i, j;

	/* For -ERANGE (i.e. spi not falling into allocated stack slots), we
	 * will do check_mem_access to check and update stack bounds later, so
	 * return true for that case.
	 */
	spi = iter_get_spi(env, reg, nr_slots);
	if (spi == -ERANGE)
		return true;
	if (spi < 0)
		return false;

	for (i = 0; i < nr_slots; i++) {
		struct bpf_stack_state *slot = &state->stack[spi - i];

		for (j = 0; j < BPF_REG_SIZE; j++)
			if (slot->slot_type[j] == STACK_ITER)
				return false;
	}

	return true;
}

static int is_iter_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
				   struct btf *btf, u32 btf_id, int nr_slots)
{
	struct bpf_func_state *state = func(env, reg);
	int spi, i, j;

	spi = iter_get_spi(env, reg, nr_slots);
	if (spi < 0)
		return -EINVAL;

	for (i = 0; i < nr_slots; i++) {
		struct bpf_stack_state *slot = &state->stack[spi - i];
		struct bpf_reg_state *st = &slot->spilled_ptr;

		if (st->type & PTR_UNTRUSTED)
			return -EPROTO;
		/* only main (first) slot has ref_obj_id set */
		if (i == 0 && !st->ref_obj_id)
			return -EINVAL;
		if (i != 0 && st->ref_obj_id)
			return -EINVAL;
		if (st->iter.btf != btf || st->iter.btf_id != btf_id)
			return -EINVAL;

		for (j = 0; j < BPF_REG_SIZE; j++)
			if (slot->slot_type[j] != STACK_ITER)
				return -EINVAL;
	}

	return 0;
}

/* Check if given stack slot is "special":
 *   - spilled register state (STACK_SPILL);
 *   - dynptr state (STACK_DYNPTR);
 *   - iter state (STACK_ITER).
 */
static bool is_stack_slot_special(const struct bpf_stack_state *stack)
{
	enum bpf_stack_slot_type type = stack->slot_type[BPF_REG_SIZE - 1];

	switch (type) {
	case STACK_SPILL:
	case STACK_DYNPTR:
	case STACK_ITER:
		return true;
	case STACK_INVALID:
	case STACK_MISC:
	case STACK_ZERO:
		return false;
	default:
		WARN_ONCE(1, "unknown stack slot type %d\n", type);
		return true;
	}
}

/* The reg state of a pointer or a bounded scalar was saved when
 * it was spilled to the stack.
 */
static bool is_spilled_reg(const struct bpf_stack_state *stack)
{
	return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL;
}

static bool is_spilled_scalar_reg(const struct bpf_stack_state *stack)
{
	return stack->slot_type[BPF_REG_SIZE - 1] == STACK_SPILL &&
	       stack->spilled_ptr.type == SCALAR_VALUE;
}

static bool is_spilled_scalar_reg64(const struct bpf_stack_state *stack)
{
	return stack->slot_type[0] == STACK_SPILL &&
	       stack->spilled_ptr.type == SCALAR_VALUE;
}

/* Mark stack slot as STACK_MISC, unless it is already STACK_INVALID, in which
 * case they are equivalent, or it's STACK_ZERO, in which case we preserve
 * more precise STACK_ZERO.
 * Note, in uprivileged mode leaving STACK_INVALID is wrong, so we take
 * env->allow_ptr_leaks into account and force STACK_MISC, if necessary.
 */
static void mark_stack_slot_misc(struct bpf_verifier_env *env, u8 *stype)
{
	if (*stype == STACK_ZERO)
		return;
	if (env->allow_ptr_leaks && *stype == STACK_INVALID)
		return;
	*stype = STACK_MISC;
}

static void scrub_spilled_slot(u8 *stype)
{
	if (*stype != STACK_INVALID)
		*stype = STACK_MISC;
}

/* copy array src of length n * size bytes to dst. dst is reallocated if it's too
 * small to hold src. This is different from krealloc since we don't want to preserve
 * the contents of dst.
 *
 * Leaves dst untouched if src is NULL or length is zero. Returns NULL if memory could
 * not be allocated.
 */
static void *copy_array(void *dst, const void *src, size_t n, size_t size, gfp_t flags)
{
	size_t alloc_bytes;
	void *orig = dst;
	size_t bytes;

	if (ZERO_OR_NULL_PTR(src))
		goto out;

	if (unlikely(check_mul_overflow(n, size, &bytes)))
		return NULL;

	alloc_bytes = max(ksize(orig), kmalloc_size_roundup(bytes));
	dst = krealloc(orig, alloc_bytes, flags);
	if (!dst) {
		kfree(orig);
		return NULL;
	}

	memcpy(dst, src, bytes);
out:
	return dst ? dst : ZERO_SIZE_PTR;
}

/* resize an array from old_n items to new_n items. the array is reallocated if it's too
 * small to hold new_n items. new items are zeroed out if the array grows.
 *
 * Contrary to krealloc_array, does not free arr if new_n is zero.
 */
static void *realloc_array(void *arr, size_t old_n, size_t new_n, size_t size)
{
	size_t alloc_size;
	void *new_arr;

	if (!new_n || old_n == new_n)
		goto out;

	alloc_size = kmalloc_size_roundup(size_mul(new_n, size));
	new_arr = krealloc(arr, alloc_size, GFP_KERNEL);
	if (!new_arr) {
		kfree(arr);
		return NULL;
	}
	arr = new_arr;

	if (new_n > old_n)
		memset(arr + old_n * size, 0, (new_n - old_n) * size);

out:
	return arr ? arr : ZERO_SIZE_PTR;
}

static int copy_reference_state(struct bpf_func_state *dst, const struct bpf_func_state *src)
{
	dst->refs = copy_array(dst->refs, src->refs, src->acquired_refs,
			       sizeof(struct bpf_reference_state), GFP_KERNEL);
	if (!dst->refs)
		return -ENOMEM;

	dst->acquired_refs = src->acquired_refs;
	return 0;
}

static int copy_stack_state(struct bpf_func_state *dst, const struct bpf_func_state *src)
{
	size_t n = src->allocated_stack / BPF_REG_SIZE;

	dst->stack = copy_array(dst->stack, src->stack, n, sizeof(struct bpf_stack_state),
				GFP_KERNEL);
	if (!dst->stack)
		return -ENOMEM;

	dst->allocated_stack = src->allocated_stack;
	return 0;
}

static int resize_reference_state(struct bpf_func_state *state, size_t n)
{
	state->refs = realloc_array(state->refs, state->acquired_refs, n,
				    sizeof(struct bpf_reference_state));
	if (!state->refs)
		return -ENOMEM;

	state->acquired_refs = n;
	return 0;
}

/* Possibly update state->allocated_stack to be at least size bytes. Also
 * possibly update the function's high-water mark in its bpf_subprog_info.
 */
static int grow_stack_state(struct bpf_verifier_env *env, struct bpf_func_state *state, int size)
{
	size_t old_n = state->allocated_stack / BPF_REG_SIZE, n;

	/* The stack size is always a multiple of BPF_REG_SIZE. */
	size = round_up(size, BPF_REG_SIZE);
	n = size / BPF_REG_SIZE;

	if (old_n >= n)
		return 0;

	state->stack = realloc_array(state->stack, old_n, n, sizeof(struct bpf_stack_state));
	if (!state->stack)
		return -ENOMEM;

	state->allocated_stack = size;

	/* update known max for given subprogram */
	if (env->subprog_info[state->subprogno].stack_depth < size)
		env->subprog_info[state->subprogno].stack_depth = size;

	return 0;
}

/* Acquire a pointer id from the env and update the state->refs to include
 * this new pointer reference.
 * On success, returns a valid pointer id to associate with the register
 * On failure, returns a negative errno.
 */
static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx)
{
	struct bpf_func_state *state = cur_func(env);
	int new_ofs = state->acquired_refs;
	int id, err;

	err = resize_reference_state(state, state->acquired_refs + 1);
	if (err)
		return err;
	id = ++env->id_gen;
	state->refs[new_ofs].id = id;
	state->refs[new_ofs].insn_idx = insn_idx;
	state->refs[new_ofs].callback_ref = state->in_callback_fn ? state->frameno : 0;

	return id;
}

/* release function corresponding to acquire_reference_state(). Idempotent. */
static int release_reference_state(struct bpf_func_state *state, int ptr_id)
{
	int i, last_idx;

	last_idx = state->acquired_refs - 1;
	for (i = 0; i < state->acquired_refs; i++) {
		if (state->refs[i].id == ptr_id) {
			/* Cannot release caller references in callbacks */
			if (state->in_callback_fn && state->refs[i].callback_ref != state->frameno)
				return -EINVAL;
			if (last_idx && i != last_idx)
				memcpy(&state->refs[i], &state->refs[last_idx],
				       sizeof(*state->refs));
			memset(&state->refs[last_idx], 0, sizeof(*state->refs));
			state->acquired_refs--;
			return 0;
		}
	}
	return -EINVAL;
}

static void free_func_state(struct bpf_func_state *state)
{
	if (!state)
		return;
	kfree(state->refs);
	kfree(state->stack);
	kfree(state);
}

static void clear_jmp_history(struct bpf_verifier_state *state)
{
	kfree(state->jmp_history);
	state->jmp_history = NULL;
	state->jmp_history_cnt = 0;
}

static void free_verifier_state(struct bpf_verifier_state *state,
				bool free_self)
{
	int i;

	for (i = 0; i <= state->curframe; i++) {
		free_func_state(state->frame[i]);
		state->frame[i] = NULL;
	}
	clear_jmp_history(state);
	if (free_self)
		kfree(state);
}

/* copy verifier state from src to dst growing dst stack space
 * when necessary to accommodate larger src stack
 */
static int copy_func_state(struct bpf_func_state *dst,
			   const struct bpf_func_state *src)
{
	int err;

	memcpy(dst, src, offsetof(struct bpf_func_state, acquired_refs));
	err = copy_reference_state(dst, src);
	if (err)
		return err;
	return copy_stack_state(dst, src);
}

static int copy_verifier_state(struct bpf_verifier_state *dst_state,
			       const struct bpf_verifier_state *src)
{
	struct bpf_func_state *dst;
	int i, err;

	dst_state->jmp_history = copy_array(dst_state->jmp_history, src->jmp_history,
					  src->jmp_history_cnt, sizeof(*dst_state->jmp_history),
					  GFP_USER);
	if (!dst_state->jmp_history)
		return -ENOMEM;
	dst_state->jmp_history_cnt = src->jmp_history_cnt;

	/* if dst has more stack frames then src frame, free them, this is also
	 * necessary in case of exceptional exits using bpf_throw.
	 */
	for (i = src->curframe + 1; i <= dst_state->curframe; i++) {
		free_func_state(dst_state->frame[i]);
		dst_state->frame[i] = NULL;
	}
	dst_state->speculative = src->speculative;
	dst_state->active_rcu_lock = src->active_rcu_lock;
	dst_state->active_preempt_lock = src->active_preempt_lock;
	dst_state->in_sleepable = src->in_sleepable;
	dst_state->curframe = src->curframe;
	dst_state->active_lock.ptr = src->active_lock.ptr;
	dst_state->active_lock.id = src->active_lock.id;
	dst_state->branches = src->branches;
	dst_state->parent = src->parent;
	dst_state->first_insn_idx = src->first_insn_idx;
	dst_state->last_insn_idx = src->last_insn_idx;
	dst_state->dfs_depth = src->dfs_depth;
	dst_state->callback_unroll_depth = src->callback_unroll_depth;
	dst_state->used_as_loop_entry = src->used_as_loop_entry;
	dst_state->may_goto_depth = src->may_goto_depth;
	for (i = 0; i <= src->curframe; i++) {
		dst = dst_state->frame[i];
		if (!dst) {
			dst = kzalloc(sizeof(*dst), GFP_KERNEL);
			if (!dst)
				return -ENOMEM;
			dst_state->frame[i] = dst;
		}
		err = copy_func_state(dst, src->frame[i]);
		if (err)
			return err;
	}
	return 0;
}

static u32 state_htab_size(struct bpf_verifier_env *env)
{
	return env->prog->len;
}

static struct bpf_verifier_state_list **explored_state(struct bpf_verifier_env *env, int idx)
{
	struct bpf_verifier_state *cur = env->cur_state;
	struct bpf_func_state *state = cur->frame[cur->curframe];

	return &env->explored_states[(idx ^ state->callsite) % state_htab_size(env)];
}

static bool same_callsites(struct bpf_verifier_state *a, struct bpf_verifier_state *b)
{
	int fr;

	if (a->curframe != b->curframe)
		return false;

	for (fr = a->curframe; fr >= 0; fr--)
		if (a->frame[fr]->callsite != b->frame[fr]->callsite)
			return false;

	return true;
}

/* Open coded iterators allow back-edges in the state graph in order to
 * check unbounded loops that iterators.
 *
 * In is_state_visited() it is necessary to know if explored states are
 * part of some loops in order to decide whether non-exact states
 * comparison could be used:
 * - non-exact states comparison establishes sub-state relation and uses
 *   read and precision marks to do so, these marks are propagated from
 *   children states and thus are not guaranteed to be final in a loop;
 * - exact states comparison just checks if current and explored states
 *   are identical (and thus form a back-edge).
 *
 * Paper "A New Algorithm for Identifying Loops in Decompilation"
 * by Tao Wei, Jian Mao, Wei Zou and Yu Chen [1] presents a convenient
 * algorithm for loop structure detection and gives an overview of
 * relevant terminology. It also has helpful illustrations.
 *
 * [1] https://api.semanticscholar.org/CorpusID:15784067
 *
 * We use a similar algorithm but because loop nested structure is
 * irrelevant for verifier ours is significantly simpler and resembles
 * strongly connected components algorithm from Sedgewick's textbook.
 *
 * Define topmost loop entry as a first node of the loop traversed in a
 * depth first search starting from initial state. The goal of the loop
 * tracking algorithm is to associate topmost loop entries with states
 * derived from these entries.
 *
 * For each step in the DFS states traversal algorithm needs to identify
 * the following situations:
 *
 *          initial                     initial                   initial
 *            |                           |                         |
 *            V                           V                         V
 *           ...                         ...           .---------> hdr
 *            |                           |            |            |
 *            V                           V            |            V
 *           cur                     .-> succ          |    .------...
 *            |                      |    |            |    |       |
 *            V                      |    V            |    V       V
 *           succ                    '-- cur           |   ...     ...
 *                                                     |    |       |
 *                                                     |    V       V
 *                                                     |   succ <- cur
 *                                                     |    |
 *                                                     |    V
 *                                                     |   ...
 *                                                     |    |
 *                                                     '----'
 *
 *  (A) successor state of cur   (B) successor state of cur or it's entry
 *      not yet traversed            are in current DFS path, thus cur and succ
 *                                   are members of the same outermost loop
 *
 *                      initial                  initial
 *                        |                        |
 *                        V                        V
 *                       ...                      ...
 *                        |                        |
 *                        V                        V
 *                .------...               .------...
 *                |       |                |       |
 *                V       V                V       V
 *           .-> hdr     ...              ...     ...
 *           |    |       |                |       |
 *           |    V       V                V       V
 *           |   succ <- cur              succ <- cur
 *           |    |                        |
 *           |    V                        V
 *           |   ...                      ...
 *           |    |                        |
 *           '----'                       exit
 *
 * (C) successor state of cur is a part of some loop but this loop
 *     does not include cur or successor state is not in a loop at all.
 *
 * Algorithm could be described as the following python code:
 *
 *     traversed = set()   # Set of traversed nodes
 *     entries = {}        # Mapping from node to loop entry
 *     depths = {}         # Depth level assigned to graph node
 *     path = set()        # Current DFS path
 *
 *     # Find outermost loop entry known for n
 *     def get_loop_entry(n):
 *         h = entries.get(n, None)
 *         while h in entries and entries[h] != h:
 *             h = entries[h]
 *         return h
 *
 *     # Update n's loop entry if h's outermost entry comes
 *     # before n's outermost entry in current DFS path.
 *     def update_loop_entry(n, h):
 *         n1 = get_loop_entry(n) or n
 *         h1 = get_loop_entry(h) or h
 *         if h1 in path and depths[h1] <= depths[n1]:
 *             entries[n] = h1
 *
 *     def dfs(n, depth):
 *         traversed.add(n)
 *         path.add(n)
 *         depths[n] = depth
 *         for succ in G.successors(n):
 *             if succ not in traversed:
 *                 # Case A: explore succ and update cur's loop entry
 *                 #         only if succ's entry is in current DFS path.
 *                 dfs(succ, depth + 1)
 *                 h = get_loop_entry(succ)
 *                 update_loop_entry(n, h)
 *             else:
 *                 # Case B or C depending on `h1 in path` check in update_loop_entry().
 *                 update_loop_entry(n, succ)
 *         path.remove(n)
 *
 * To adapt this algorithm for use with verifier:
 * - use st->branch == 0 as a signal that DFS of succ had been finished
 *   and cur's loop entry has to be updated (case A), handle this in
 *   update_branch_counts();
 * - use st->branch > 0 as a signal that st is in the current DFS path;
 * - handle cases B and C in is_state_visited();
 * - update topmost loop entry for intermediate states in get_loop_entry().
 */
static struct bpf_verifier_state *get_loop_entry(struct bpf_verifier_state *st)
{
	struct bpf_verifier_state *topmost = st->loop_entry, *old;

	while (topmost && topmost->loop_entry && topmost != topmost->loop_entry)
		topmost = topmost->loop_entry;
	/* Update loop entries for intermediate states to avoid this
	 * traversal in future get_loop_entry() calls.
	 */
	while (st && st->loop_entry != topmost) {
		old = st->loop_entry;
		st->loop_entry = topmost;
		st = old;
	}
	return topmost;
}

static void update_loop_entry(struct bpf_verifier_state *cur, struct bpf_verifier_state *hdr)
{
	struct bpf_verifier_state *cur1, *hdr1;

	cur1 = get_loop_entry(cur) ?: cur;
	hdr1 = get_loop_entry(hdr) ?: hdr;
	/* The head1->branches check decides between cases B and C in
	 * comment for get_loop_entry(). If hdr1->branches == 0 then
	 * head's topmost loop entry is not in current DFS path,
	 * hence 'cur' and 'hdr' are not in the same loop and there is
	 * no need to update cur->loop_entry.
	 */
	if (hdr1->branches && hdr1->dfs_depth <= cur1->dfs_depth) {
		cur->loop_entry = hdr;
		hdr->used_as_loop_entry = true;
	}
}

static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
{
	while (st) {
		u32 br = --st->branches;

		/* br == 0 signals that DFS exploration for 'st' is finished,
		 * thus it is necessary to update parent's loop entry if it
		 * turned out that st is a part of some loop.
		 * This is a part of 'case A' in get_loop_entry() comment.
		 */
		if (br == 0 && st->parent && st->loop_entry)
			update_loop_entry(st->parent, st->loop_entry);

		/* WARN_ON(br > 1) technically makes sense here,
		 * but see comment in push_stack(), hence:
		 */
		WARN_ONCE((int)br < 0,
			  "BUG update_branch_counts:branches_to_explore=%d\n",
			  br);
		if (br)
			break;
		st = st->parent;
	}
}

static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
		     int *insn_idx, bool pop_log)
{
	struct bpf_verifier_state *cur = env->cur_state;
	struct bpf_verifier_stack_elem *elem, *head = env->head;
	int err;

	if (env->head == NULL)
		return -ENOENT;

	if (cur) {
		err = copy_verifier_state(cur, &head->st);
		if (err)
			return err;
	}
	if (pop_log)
		bpf_vlog_reset(&env->log, head->log_pos);
	if (insn_idx)
		*insn_idx = head->insn_idx;
	if (prev_insn_idx)
		*prev_insn_idx = head->prev_insn_idx;
	elem = head->next;
	free_verifier_state(&head->st, false);
	kfree(head);
	env->head = elem;
	env->stack_size--;
	return 0;
}

static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
					     int insn_idx, int prev_insn_idx,
					     bool speculative)
{
	struct bpf_verifier_state *cur = env->cur_state;
	struct bpf_verifier_stack_elem *elem;
	int err;

	elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
	if (!elem)
		goto err;

	elem->insn_idx = insn_idx;
	elem->prev_insn_idx = prev_insn_idx;
	elem->next = env->head;
	elem->log_pos = env->log.end_pos;
	env->head = elem;
	env->stack_size++;
	err = copy_verifier_state(&elem->st, cur);
	if (err)
		goto err;
	elem->st.speculative |= speculative;
	if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
		verbose(env, "The sequence of %d jumps is too complex.\n",
			env->stack_size);
		goto err;
	}
	if (elem->st.parent) {
		++elem->st.parent->branches;
		/* WARN_ON(branches > 2) technically makes sense here,
		 * but
		 * 1. speculative states will bump 'branches' for non-branch
		 * instructions
		 * 2. is_state_visited() heuristics may decide not to create
		 * a new state for a sequence of branches and all such current
		 * and cloned states will be pointing to a single parent state
		 * which might have large 'branches' count.
		 */
	}
	return &elem->st;
err:
	free_verifier_state(env->cur_state, true);
	env->cur_state = NULL;
	/* pop all elements and return */
	while (!pop_stack(env, NULL, NULL, false));
	return NULL;
}

#define CALLER_SAVED_REGS 6
static const int caller_saved[CALLER_SAVED_REGS] = {
	BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
};

/* This helper doesn't clear reg->id */
static void ___mark_reg_known(struct bpf_reg_state *reg, u64 imm)
{
	reg->var_off = tnum_const(imm);
	reg->smin_value = (s64)imm;
	reg->smax_value = (s64)imm;
	reg->umin_value = imm;
	reg->umax_value = imm;

	reg->s32_min_value = (s32)imm;
	reg->s32_max_value = (s32)imm;
	reg->u32_min_value = (u32)imm;
	reg->u32_max_value = (u32)imm;
}

/* Mark the unknown part of a register (variable offset or scalar value) as
 * known to have the value @imm.
 */
static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm)
{
	/* Clear off and union(map_ptr, range) */
	memset(((u8 *)reg) + sizeof(reg->type), 0,
	       offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type));
	reg->id = 0;
	reg->ref_obj_id = 0;
	___mark_reg_known(reg, imm);
}

static void __mark_reg32_known(struct bpf_reg_state *reg, u64 imm)
{
	reg->var_off = tnum_const_subreg(reg->var_off, imm);
	reg->s32_min_value = (s32)imm;
	reg->s32_max_value = (s32)imm;
	reg->u32_min_value = (u32)imm;
	reg->u32_max_value = (u32)imm;
}

/* Mark the 'variable offset' part of a register as zero.  This should be
 * used only on registers holding a pointer type.
 */
static void __mark_reg_known_zero(struct bpf_reg_state *reg)
{
	__mark_reg_known(reg, 0);
}

static void __mark_reg_const_zero(const struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
	__mark_reg_known(reg, 0);
	reg->type = SCALAR_VALUE;
	/* all scalars are assumed imprecise initially (unless unprivileged,
	 * in which case everything is forced to be precise)
	 */
	reg->precise = !env->bpf_capable;
}

static void mark_reg_known_zero(struct bpf_verifier_env *env,
				struct bpf_reg_state *regs, u32 regno)
{
	if (WARN_ON(regno >= MAX_BPF_REG)) {
		verbose(env, "mark_reg_known_zero(regs, %u)\n", regno);
		/* Something bad happened, let's kill all regs */
		for (regno = 0; regno < MAX_BPF_REG; regno++)
			__mark_reg_not_init(env, regs + regno);
		return;
	}
	__mark_reg_known_zero(regs + regno);
}

static void __mark_dynptr_reg(struct bpf_reg_state *reg, enum bpf_dynptr_type type,
			      bool first_slot, int dynptr_id)
{
	/* reg->type has no meaning for STACK_DYNPTR, but when we set reg for
	 * callback arguments, it does need to be CONST_PTR_TO_DYNPTR, so simply
	 * set it unconditionally as it is ignored for STACK_DYNPTR anyway.
	 */
	__mark_reg_known_zero(reg);
	reg->type = CONST_PTR_TO_DYNPTR;
	/* Give each dynptr a unique id to uniquely associate slices to it. */
	reg->id = dynptr_id;
	reg->dynptr.type = type;
	reg->dynptr.first_slot = first_slot;
}

static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
{
	if (base_type(reg->type) == PTR_TO_MAP_VALUE) {
		const struct bpf_map *map = reg->map_ptr;

		if (map->inner_map_meta) {
			reg->type = CONST_PTR_TO_MAP;
			reg->map_ptr = map->inner_map_meta;
			/* transfer reg's id which is unique for every map_lookup_elem
			 * as UID of the inner map.
			 */
			if (btf_record_has_field(map->inner_map_meta->record, BPF_TIMER))
				reg->map_uid = reg->id;
			if (btf_record_has_field(map->inner_map_meta->record, BPF_WORKQUEUE))
				reg->map_uid = reg->id;
		} else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {
			reg->type = PTR_TO_XDP_SOCK;
		} else if (map->map_type == BPF_MAP_TYPE_SOCKMAP ||
			   map->map_type == BPF_MAP_TYPE_SOCKHASH) {
			reg->type = PTR_TO_SOCKET;
		} else {
			reg->type = PTR_TO_MAP_VALUE;
		}
		return;
	}

	reg->type &= ~PTR_MAYBE_NULL;
}

static void mark_reg_graph_node(struct bpf_reg_state *regs, u32 regno,
				struct btf_field_graph_root *ds_head)
{
	__mark_reg_known_zero(&regs[regno]);
	regs[regno].type = PTR_TO_BTF_ID | MEM_ALLOC;
	regs[regno].btf = ds_head->btf;
	regs[regno].btf_id = ds_head->value_btf_id;
	regs[regno].off = ds_head->node_offset;
}

static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
{
	return type_is_pkt_pointer(reg->type);
}

static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg)
{
	return reg_is_pkt_pointer(reg) ||
	       reg->type == PTR_TO_PACKET_END;
}

static bool reg_is_dynptr_slice_pkt(const struct bpf_reg_state *reg)
{
	return base_type(reg->type) == PTR_TO_MEM &&
		(reg->type & DYNPTR_TYPE_SKB || reg->type & DYNPTR_TYPE_XDP);
}

/* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg,
				    enum bpf_reg_type which)
{
	/* The register can already have a range from prior markings.
	 * This is fine as long as it hasn't been advanced from its
	 * origin.
	 */
	return reg->type == which &&
	       reg->id == 0 &&
	       reg->off == 0 &&
	       tnum_equals_const(reg->var_off, 0);
}

/* Reset the min/max bounds of a register */
static void __mark_reg_unbounded(struct bpf_reg_state *reg)
{
	reg->smin_value = S64_MIN;
	reg->smax_value = S64_MAX;
	reg->umin_value = 0;
	reg->umax_value = U64_MAX;

	reg->s32_min_value = S32_MIN;
	reg->s32_max_value = S32_MAX;
	reg->u32_min_value = 0;
	reg->u32_max_value = U32_MAX;
}

static void __mark_reg64_unbounded(struct bpf_reg_state *reg)
{
	reg->smin_value = S64_MIN;
	reg->smax_value = S64_MAX;
	reg->umin_value = 0;
	reg->umax_value = U64_MAX;
}

static void __mark_reg32_unbounded(struct bpf_reg_state *reg)
{
	reg->s32_min_value = S32_MIN;
	reg->s32_max_value = S32_MAX;
	reg->u32_min_value = 0;
	reg->u32_max_value = U32_MAX;
}

static void __update_reg32_bounds(struct bpf_reg_state *reg)
{
	struct tnum var32_off = tnum_subreg(reg->var_off);

	/* min signed is max(sign bit) | min(other bits) */
	reg->s32_min_value = max_t(s32, reg->s32_min_value,
			var32_off.value | (var32_off.mask & S32_MIN));
	/* max signed is min(sign bit) | max(other bits) */
	reg->s32_max_value = min_t(s32, reg->s32_max_value,
			var32_off.value | (var32_off.mask & S32_MAX));
	reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)var32_off.value);
	reg->u32_max_value = min(reg->u32_max_value,
				 (u32)(var32_off.value | var32_off.mask));
}

static void __update_reg64_bounds(struct bpf_reg_state *reg)
{
	/* min signed is max(sign bit) | min(other bits) */
	reg->smin_value = max_t(s64, reg->smin_value,
				reg->var_off.value | (reg->var_off.mask & S64_MIN));
	/* max signed is min(sign bit) | max(other bits) */
	reg->smax_value = min_t(s64, reg->smax_value,
				reg->var_off.value | (reg->var_off.mask & S64_MAX));
	reg->umin_value = max(reg->umin_value, reg->var_off.value);
	reg->umax_value = min(reg->umax_value,
			      reg->var_off.value | reg->var_off.mask);
}

static void __update_reg_bounds(struct bpf_reg_state *reg)
{
	__update_reg32_bounds(reg);
	__update_reg64_bounds(reg);
}

/* Uses signed min/max values to inform unsigned, and vice-versa */
static void __reg32_deduce_bounds(struct bpf_reg_state *reg)
{
	/* If upper 32 bits of u64/s64 range don't change, we can use lower 32
	 * bits to improve our u32/s32 boundaries.
	 *
	 * E.g., the case where we have upper 32 bits as zero ([10, 20] in
	 * u64) is pretty trivial, it's obvious that in u32 we'll also have
	 * [10, 20] range. But this property holds for any 64-bit range as
	 * long as upper 32 bits in that entire range of values stay the same.
	 *
	 * E.g., u64 range [0x10000000A, 0x10000000F] ([4294967306, 4294967311]
	 * in decimal) has the same upper 32 bits throughout all the values in
	 * that range. As such, lower 32 bits form a valid [0xA, 0xF] ([10, 15])
	 * range.
	 *
	 * Note also, that [0xA, 0xF] is a valid range both in u32 and in s32,
	 * following the rules outlined below about u64/s64 correspondence
	 * (which equally applies to u32 vs s32 correspondence). In general it
	 * depends on actual hexadecimal values of 32-bit range. They can form
	 * only valid u32, or only valid s32 ranges in some cases.
	 *
	 * So we use all these insights to derive bounds for subregisters here.
	 */
	if ((reg->umin_value >> 32) == (reg->umax_value >> 32)) {
		/* u64 to u32 casting preserves validity of low 32 bits as
		 * a range, if upper 32 bits are the same
		 */
		reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->umin_value);
		reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->umax_value);

		if ((s32)reg->umin_value <= (s32)reg->umax_value) {
			reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value);
			reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value);
		}
	}
	if ((reg->smin_value >> 32) == (reg->smax_value >> 32)) {
		/* low 32 bits should form a proper u32 range */
		if ((u32)reg->smin_value <= (u32)reg->smax_value) {
			reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)reg->smin_value);
			reg->u32_max_value = min_t(u32, reg->u32_max_value, (u32)reg->smax_value);
		}
		/* low 32 bits should form a proper s32 range */
		if ((s32)reg->smin_value <= (s32)reg->smax_value) {
			reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value);
			reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value);
		}
	}
	/* Special case where upper bits form a small sequence of two
	 * sequential numbers (in 32-bit unsigned space, so 0xffffffff to
	 * 0x00000000 is also valid), while lower bits form a proper s32 range
	 * going from negative numbers to positive numbers. E.g., let's say we
	 * have s64 range [-1, 1] ([0xffffffffffffffff, 0x0000000000000001]).
	 * Possible s64 values are {-1, 0, 1} ({0xffffffffffffffff,
	 * 0x0000000000000000, 0x00000000000001}). Ignoring upper 32 bits,
	 * we still get a valid s32 range [-1, 1] ([0xffffffff, 0x00000001]).
	 * Note that it doesn't have to be 0xffffffff going to 0x00000000 in
	 * upper 32 bits. As a random example, s64 range
	 * [0xfffffff0fffffff0; 0xfffffff100000010], forms a valid s32 range
	 * [-16, 16] ([0xfffffff0; 0x00000010]) in its 32 bit subregister.
	 */
	if ((u32)(reg->umin_value >> 32) + 1 == (u32)(reg->umax_value >> 32) &&
	    (s32)reg->umin_value < 0 && (s32)reg->umax_value >= 0) {
		reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->umin_value);
		reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->umax_value);
	}
	if ((u32)(reg->smin_value >> 32) + 1 == (u32)(reg->smax_value >> 32) &&
	    (s32)reg->smin_value < 0 && (s32)reg->smax_value >= 0) {
		reg->s32_min_value = max_t(s32, reg->s32_min_value, (s32)reg->smin_value);
		reg->s32_max_value = min_t(s32, reg->s32_max_value, (s32)reg->smax_value);
	}
	/* if u32 range forms a valid s32 range (due to matching sign bit),
	 * try to learn from that
	 */
	if ((s32)reg->u32_min_value <= (s32)reg->u32_max_value) {
		reg->s32_min_value = max_t(s32, reg->s32_min_value, reg->u32_min_value);
		reg->s32_max_value = min_t(s32, reg->s32_max_value, reg->u32_max_value);
	}
	/* If we cannot cross the sign boundary, then signed and unsigned bounds
	 * are the same, so combine.  This works even in the negative case, e.g.
	 * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
	 */
	if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) {
		reg->u32_min_value = max_t(u32, reg->s32_min_value, reg->u32_min_value);
		reg->u32_max_value = min_t(u32, reg->s32_max_value, reg->u32_max_value);
	}
}

static void __reg64_deduce_bounds(struct bpf_reg_state *reg)
{
	/* If u64 range forms a valid s64 range (due to matching sign bit),
	 * try to learn from that. Let's do a bit of ASCII art to see when
	 * this is happening. Let's take u64 range first:
	 *
	 * 0             0x7fffffffffffffff 0x8000000000000000        U64_MAX
	 * |-------------------------------|--------------------------------|
	 *
	 * Valid u64 range is formed when umin and umax are anywhere in the
	 * range [0, U64_MAX], and umin <= umax. u64 case is simple and
	 * straightforward. Let's see how s64 range maps onto the same range
	 * of values, annotated below the line for comparison:
	 *
	 * 0             0x7fffffffffffffff 0x8000000000000000        U64_MAX
	 * |-------------------------------|--------------------------------|
	 * 0                        S64_MAX S64_MIN                        -1
	 *
	 * So s64 values basically start in the middle and they are logically
	 * contiguous to the right of it, wrapping around from -1 to 0, and
	 * then finishing as S64_MAX (0x7fffffffffffffff) right before
	 * S64_MIN. We can try drawing the continuity of u64 vs s64 values
	 * more visually as mapped to sign-agnostic range of hex values.
	 *
	 *  u64 start                                               u64 end
	 *  _______________________________________________________________
	 * /                                                               \
	 * 0             0x7fffffffffffffff 0x8000000000000000        U64_MAX
	 * |-------------------------------|--------------------------------|
	 * 0                        S64_MAX S64_MIN                        -1
	 *                                / \
	 * >------------------------------   ------------------------------->
	 * s64 continues...        s64 end   s64 start          s64 "midpoint"
	 *
	 * What this means is that, in general, we can't always derive
	 * something new about u64 from any random s64 range, and vice versa.
	 *
	 * But we can do that in two particular cases. One is when entire
	 * u64/s64 range is *entirely* contained within left half of the above
	 * diagram or when it is *entirely* contained in the right half. I.e.:
	 *
	 * |-------------------------------|--------------------------------|
	 *     ^                   ^            ^                 ^
	 *     A                   B            C                 D
	 *
	 * [A, B] and [C, D] are contained entirely in their respective halves
	 * and form valid contiguous ranges as both u64 and s64 values. [A, B]
	 * will be non-negative both as u64 and s64 (and in fact it will be
	 * identical ranges no matter the signedness). [C, D] treated as s64
	 * will be a range of negative values, while in u64 it will be
	 * non-negative range of values larger than 0x8000000000000000.
	 *
	 * Now, any other range here can't be represented in both u64 and s64
	 * simultaneously. E.g., [A, C], [A, D], [B, C], [B, D] are valid
	 * contiguous u64 ranges, but they are discontinuous in s64. [B, C]
	 * in s64 would be properly presented as [S64_MIN, C] and [B, S64_MAX],
	 * for example. Similarly, valid s64 range [D, A] (going from negative
	 * to positive values), would be two separate [D, U64_MAX] and [0, A]
	 * ranges as u64. Currently reg_state can't represent two segments per
	 * numeric domain, so in such situations we can only derive maximal
	 * possible range ([0, U64_MAX] for u64, and [S64_MIN, S64_MAX] for s64).
	 *
	 * So we use these facts to derive umin/umax from smin/smax and vice
	 * versa only if they stay within the same "half". This is equivalent
	 * to checking sign bit: lower half will have sign bit as zero, upper
	 * half have sign bit 1. Below in code we simplify this by just
	 * casting umin/umax as smin/smax and checking if they form valid
	 * range, and vice versa. Those are equivalent checks.
	 */
	if ((s64)reg->umin_value <= (s64)reg->umax_value) {
		reg->smin_value = max_t(s64, reg->smin_value, reg->umin_value);
		reg->smax_value = min_t(s64, reg->smax_value, reg->umax_value);
	}
	/* If we cannot cross the sign boundary, then signed and unsigned bounds
	 * are the same, so combine.  This works even in the negative case, e.g.
	 * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
	 */
	if ((u64)reg->smin_value <= (u64)reg->smax_value) {
		reg->umin_value = max_t(u64, reg->smin_value, reg->umin_value);
		reg->umax_value = min_t(u64, reg->smax_value, reg->umax_value);
	}
}

static void __reg_deduce_mixed_bounds(struct bpf_reg_state *reg)
{
	/* Try to tighten 64-bit bounds from 32-bit knowledge, using 32-bit
	 * values on both sides of 64-bit range in hope to have tighter range.
	 * E.g., if r1 is [0x1'00000000, 0x3'80000000], and we learn from
	 * 32-bit signed > 0 operation that s32 bounds are now [1; 0x7fffffff].
	 * With this, we can substitute 1 as low 32-bits of _low_ 64-bit bound
	 * (0x100000000 -> 0x100000001) and 0x7fffffff as low 32-bits of
	 * _high_ 64-bit bound (0x380000000 -> 0x37fffffff) and arrive at a
	 * better overall bounds for r1 as [0x1'000000001; 0x3'7fffffff].
	 * We just need to make sure that derived bounds we are intersecting
	 * with are well-formed ranges in respective s64 or u64 domain, just
	 * like we do with similar kinds of 32-to-64 or 64-to-32 adjustments.
	 */
	__u64 new_umin, new_umax;
	__s64 new_smin, new_smax;

	/* u32 -> u64 tightening, it's always well-formed */
	new_umin = (reg->umin_value & ~0xffffffffULL) | reg->u32_min_value;
	new_umax = (reg->umax_value & ~0xffffffffULL) | reg->u32_max_value;
	reg->umin_value = max_t(u64, reg->umin_value, new_umin);
	reg->umax_value = min_t(u64, reg->umax_value, new_umax);
	/* u32 -> s64 tightening, u32 range embedded into s64 preserves range validity */
	new_smin = (reg->smin_value & ~0xffffffffULL) | reg->u32_min_value;
	new_smax = (reg->smax_value & ~0xffffffffULL) | reg->u32_max_value;
	reg->smin_value = max_t(s64, reg->smin_value, new_smin);
	reg->smax_value = min_t(s64, reg->smax_value, new_smax);

	/* if s32 can be treated as valid u32 range, we can use it as well */
	if ((u32)reg->s32_min_value <= (u32)reg->s32_max_value) {
		/* s32 -> u64 tightening */
		new_umin = (reg->umin_value & ~0xffffffffULL) | (u32)reg->s32_min_value;
		new_umax = (reg->umax_value & ~0xffffffffULL) | (u32)reg->s32_max_value;
		reg->umin_value = max_t(u64, reg->umin_value, new_umin);
		reg->umax_value = min_t(u64, reg->umax_value, new_umax);
		/* s32 -> s64 tightening */
		new_smin = (reg->smin_value & ~0xffffffffULL) | (u32)reg->s32_min_value;
		new_smax = (reg->smax_value & ~0xffffffffULL) | (u32)reg->s32_max_value;
		reg->smin_value = max_t(s64, reg->smin_value, new_smin);
		reg->smax_value = min_t(s64, reg->smax_value, new_smax);
	}

	/* Here we would like to handle a special case after sign extending load,
	 * when upper bits for a 64-bit range are all 1s or all 0s.
	 *
	 * Upper bits are all 1s when register is in a range:
	 *   [0xffff_ffff_0000_0000, 0xffff_ffff_ffff_ffff]
	 * Upper bits are all 0s when register is in a range:
	 *   [0x0000_0000_0000_0000, 0x0000_0000_ffff_ffff]
	 * Together this forms are continuous range:
	 *   [0xffff_ffff_0000_0000, 0x0000_0000_ffff_ffff]
	 *
	 * Now, suppose that register range is in fact tighter:
	 *   [0xffff_ffff_8000_0000, 0x0000_0000_ffff_ffff] (R)
	 * Also suppose that it's 32-bit range is positive,
	 * meaning that lower 32-bits of the full 64-bit register
	 * are in the range:
	 *   [0x0000_0000, 0x7fff_ffff] (W)
	 *
	 * If this happens, then any value in a range:
	 *   [0xffff_ffff_0000_0000, 0xffff_ffff_7fff_ffff]
	 * is smaller than a lowest bound of the range (R):
	 *   0xffff_ffff_8000_0000
	 * which means that upper bits of the full 64-bit register
	 * can't be all 1s, when lower bits are in range (W).
	 *
	 * Note that:
	 *  - 0xffff_ffff_8000_0000 == (s64)S32_MIN
	 *  - 0x0000_0000_7fff_ffff == (s64)S32_MAX
	 * These relations are used in the conditions below.
	 */
	if (reg->s32_min_value >= 0 && reg->smin_value >= S32_MIN && reg->smax_value <= S32_MAX) {
		reg->smin_value = reg->s32_min_value;
		reg->smax_value = reg->s32_max_value;
		reg->umin_value = reg->s32_min_value;
		reg->umax_value = reg->s32_max_value;
		reg->var_off = tnum_intersect(reg->var_off,
					      tnum_range(reg->smin_value, reg->smax_value));
	}
}

static void __reg_deduce_bounds(struct bpf_reg_state *reg)
{
	__reg32_deduce_bounds(reg);
	__reg64_deduce_bounds(reg);
	__reg_deduce_mixed_bounds(reg);
}

/* Attempts to improve var_off based on unsigned min/max information */
static void __reg_bound_offset(struct bpf_reg_state *reg)
{
	struct tnum var64_off = tnum_intersect(reg->var_off,
					       tnum_range(reg->umin_value,
							  reg->umax_value));
	struct tnum var32_off = tnum_intersect(tnum_subreg(var64_off),
					       tnum_range(reg->u32_min_value,
							  reg->u32_max_value));

	reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off);
}

static void reg_bounds_sync(struct bpf_reg_state *reg)
{
	/* We might have learned new bounds from the var_off. */
	__update_reg_bounds(reg);
	/* We might have learned something about the sign bit. */
	__reg_deduce_bounds(reg);
	__reg_deduce_bounds(reg);
	/* We might have learned some bits from the bounds. */
	__reg_bound_offset(reg);
	/* Intersecting with the old var_off might have improved our bounds
	 * slightly, e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
	 * then new var_off is (0; 0x7f...fc) which improves our umax.
	 */
	__update_reg_bounds(reg);
}

static int reg_bounds_sanity_check(struct bpf_verifier_env *env,
				   struct bpf_reg_state *reg, const char *ctx)
{
	const char *msg;

	if (reg->umin_value > reg->umax_value ||
	    reg->smin_value > reg->smax_value ||
	    reg->u32_min_value > reg->u32_max_value ||
	    reg->s32_min_value > reg->s32_max_value) {
		    msg = "range bounds violation";
		    goto out;
	}

	if (tnum_is_const(reg->var_off)) {
		u64 uval = reg->var_off.value;
		s64 sval = (s64)uval;

		if (reg->umin_value != uval || reg->umax_value != uval ||
		    reg->smin_value != sval || reg->smax_value != sval) {
			msg = "const tnum out of sync with range bounds";
			goto out;
		}
	}

	if (tnum_subreg_is_const(reg->var_off)) {
		u32 uval32 = tnum_subreg(reg->var_off).value;
		s32 sval32 = (s32)uval32;

		if (reg->u32_min_value != uval32 || reg->u32_max_value != uval32 ||
		    reg->s32_min_value != sval32 || reg->s32_max_value != sval32) {
			msg = "const subreg tnum out of sync with range bounds";
			goto out;
		}
	}

	return 0;
out:
	verbose(env, "REG INVARIANTS VIOLATION (%s): %s u64=[%#llx, %#llx] "
		"s64=[%#llx, %#llx] u32=[%#x, %#x] s32=[%#x, %#x] var_off=(%#llx, %#llx)\n",
		ctx, msg, reg->umin_value, reg->umax_value,
		reg->smin_value, reg->smax_value,
		reg->u32_min_value, reg->u32_max_value,
		reg->s32_min_value, reg->s32_max_value,
		reg->var_off.value, reg->var_off.mask);
	if (env->test_reg_invariants)
		return -EFAULT;
	__mark_reg_unbounded(reg);
	return 0;
}

static bool __reg32_bound_s64(s32 a)
{
	return a >= 0 && a <= S32_MAX;
}

static void __reg_assign_32_into_64(struct bpf_reg_state *reg)
{
	reg->umin_value = reg->u32_min_value;
	reg->umax_value = reg->u32_max_value;

	/* Attempt to pull 32-bit signed bounds into 64-bit bounds but must
	 * be positive otherwise set to worse case bounds and refine later
	 * from tnum.
	 */
	if (__reg32_bound_s64(reg->s32_min_value) &&
	    __reg32_bound_s64(reg->s32_max_value)) {
		reg->smin_value = reg->s32_min_value;
		reg->smax_value = reg->s32_max_value;
	} else {
		reg->smin_value = 0;
		reg->smax_value = U32_MAX;
	}
}

/* Mark a register as having a completely unknown (scalar) value. */
static void __mark_reg_unknown_imprecise(struct bpf_reg_state *reg)
{
	/*
	 * Clear type, off, and union(map_ptr, range) and
	 * padding between 'type' and union
	 */
	memset(reg, 0, offsetof(struct bpf_reg_state, var_off));
	reg->type = SCALAR_VALUE;
	reg->id = 0;
	reg->ref_obj_id = 0;
	reg->var_off = tnum_unknown;
	reg->frameno = 0;
	reg->precise = false;
	__mark_reg_unbounded(reg);
}

/* Mark a register as having a completely unknown (scalar) value,
 * initialize .precise as true when not bpf capable.
 */
static void __mark_reg_unknown(const struct bpf_verifier_env *env,
			       struct bpf_reg_state *reg)
{
	__mark_reg_unknown_imprecise(reg);
	reg->precise = !env->bpf_capable;
}

static void mark_reg_unknown(struct bpf_verifier_env *env,
			     struct bpf_reg_state *regs, u32 regno)
{
	if (WARN_ON(regno >= MAX_BPF_REG)) {
		verbose(env, "mark_reg_unknown(regs, %u)\n", regno);
		/* Something bad happened, let's kill all regs except FP */
		for (regno = 0; regno < BPF_REG_FP; regno++)
			__mark_reg_not_init(env, regs + regno);
		return;
	}
	__mark_reg_unknown(env, regs + regno);
}

static int __mark_reg_s32_range(struct bpf_verifier_env *env,
				struct bpf_reg_state *regs,
				u32 regno,
				s32 s32_min,
				s32 s32_max)
{
	struct bpf_reg_state *reg = regs + regno;

	reg->s32_min_value = max_t(s32, reg->s32_min_value, s32_min);
	reg->s32_max_value = min_t(s32, reg->s32_max_value, s32_max);

	reg->smin_value = max_t(s64, reg->smin_value, s32_min);
	reg->smax_value = min_t(s64, reg->smax_value, s32_max);

	reg_bounds_sync(reg);

	return reg_bounds_sanity_check(env, reg, "s32_range");
}

static void __mark_reg_not_init(const struct bpf_verifier_env *env,
				struct bpf_reg_state *reg)
{
	__mark_reg_unknown(env, reg);
	reg->type = NOT_INIT;
}

static void mark_reg_not_init(struct bpf_verifier_env *env,
			      struct bpf_reg_state *regs, u32 regno)
{
	if (WARN_ON(regno >= MAX_BPF_REG)) {
		verbose(env, "mark_reg_not_init(regs, %u)\n", regno);
		/* Something bad happened, let's kill all regs except FP */
		for (regno = 0; regno < BPF_REG_FP; regno++)
			__mark_reg_not_init(env, regs + regno);
		return;
	}
	__mark_reg_not_init(env, regs + regno);
}

static void mark_btf_ld_reg(struct bpf_verifier_env *env,
			    struct bpf_reg_state *regs, u32 regno,
			    enum bpf_reg_type reg_type,
			    struct btf *btf, u32 btf_id,
			    enum bpf_type_flag flag)
{
	if (reg_type == SCALAR_VALUE) {
		mark_reg_unknown(env, regs, regno);
		return;
	}
	mark_reg_known_zero(env, regs, regno);
	regs[regno].type = PTR_TO_BTF_ID | flag;
	regs[regno].btf = btf;
	regs[regno].btf_id = btf_id;
	if (type_may_be_null(flag))
		regs[regno].id = ++env->id_gen;
}

#define DEF_NOT_SUBREG	(0)
static void init_reg_state(struct bpf_verifier_env *env,
			   struct bpf_func_state *state)
{
	struct bpf_reg_state *regs = state->regs;
	int i;

	for (i = 0; i < MAX_BPF_REG; i++) {
		mark_reg_not_init(env, regs, i);
		regs[i].live = REG_LIVE_NONE;
		regs[i].parent = NULL;
		regs[i].subreg_def = DEF_NOT_SUBREG;
	}

	/* frame pointer */
	regs[BPF_REG_FP].type = PTR_TO_STACK;
	mark_reg_known_zero(env, regs, BPF_REG_FP);
	regs[BPF_REG_FP].frameno = state->frameno;
}

static struct bpf_retval_range retval_range(s32 minval, s32 maxval)
{
	return (struct bpf_retval_range){ minval, maxval };
}

#define BPF_MAIN_FUNC (-1)
static void init_func_state(struct bpf_verifier_env *env,
			    struct bpf_func_state *state,
			    int callsite, int frameno, int subprogno)
{
	state->callsite = callsite;
	state->frameno = frameno;
	state->subprogno = subprogno;
	state->callback_ret_range = retval_range(0, 0);
	init_reg_state(env, state);
	mark_verifier_state_scratched(env);
}

/* Similar to push_stack(), but for async callbacks */
static struct bpf_verifier_state *push_async_cb(struct bpf_verifier_env *env,
						int insn_idx, int prev_insn_idx,
						int subprog, bool is_sleepable)
{
	struct bpf_verifier_stack_elem *elem;
	struct bpf_func_state *frame;

	elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
	if (!elem)
		goto err;

	elem->insn_idx = insn_idx;
	elem->prev_insn_idx = prev_insn_idx;
	elem->next = env->head;
	elem->log_pos = env->log.end_pos;
	env->head = elem;
	env->stack_size++;
	if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
		verbose(env,
			"The sequence of %d jumps is too complex for async cb.\n",
			env->stack_size);
		goto err;
	}
	/* Unlike push_stack() do not copy_verifier_state().
	 * The caller state doesn't matter.
	 * This is async callback. It starts in a fresh stack.
	 * Initialize it similar to do_check_common().
	 */
	elem->st.branches = 1;
	elem->st.in_sleepable = is_sleepable;
	frame = kzalloc(sizeof(*frame), GFP_KERNEL);
	if (!frame)
		goto err;
	init_func_state(env, frame,
			BPF_MAIN_FUNC /* callsite */,
			0 /* frameno within this callchain */,
			subprog /* subprog number within this prog */);
	elem->st.frame[0] = frame;
	return &elem->st;
err:
	free_verifier_state(env->cur_state, true);
	env->cur_state = NULL;
	/* pop all elements and return */
	while (!pop_stack(env, NULL, NULL, false));
	return NULL;
}


enum reg_arg_type {
	SRC_OP,		/* register is used as source operand */
	DST_OP,		/* register is used as destination operand */
	DST_OP_NO_MARK	/* same as above, check only, don't mark */
};

static int cmp_subprogs(const void *a, const void *b)
{
	return ((struct bpf_subprog_info *)a)->start -
	       ((struct bpf_subprog_info *)b)->start;
}

static int find_subprog(struct bpf_verifier_env *env, int off)
{
	struct bpf_subprog_info *p;

	p = bsearch(&off, env->subprog_info, env->subprog_cnt,
		    sizeof(env->subprog_info[0]), cmp_subprogs);
	if (!p)
		return -ENOENT;
	return p - env->subprog_info;

}

static int add_subprog(struct bpf_verifier_env *env, int off)
{
	int insn_cnt = env->prog->len;
	int ret;

	if (off >= insn_cnt || off < 0) {
		verbose(env, "call to invalid destination\n");
		return -EINVAL;
	}
	ret = find_subprog(env, off);
	if (ret >= 0)
		return ret;
	if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
		verbose(env, "too many subprograms\n");
		return -E2BIG;
	}
	/* determine subprog starts. The end is one before the next starts */
	env->subprog_info[env->subprog_cnt++].start = off;
	sort(env->subprog_info, env->subprog_cnt,
	     sizeof(env->subprog_info[0]), cmp_subprogs, NULL);
	return env->subprog_cnt - 1;
}

static int bpf_find_exception_callback_insn_off(struct bpf_verifier_env *env)
{
	struct bpf_prog_aux *aux = env->prog->aux;
	struct btf *btf = aux->btf;
	const struct btf_type *t;
	u32 main_btf_id, id;
	const char *name;
	int ret, i;

	/* Non-zero func_info_cnt implies valid btf */
	if (!aux->func_info_cnt)
		return 0;
	main_btf_id = aux->func_info[0].type_id;

	t = btf_type_by_id(btf, main_btf_id);
	if (!t) {
		verbose(env, "invalid btf id for main subprog in func_info\n");
		return -EINVAL;
	}

	name = btf_find_decl_tag_value(btf, t, -1, "exception_callback:");
	if (IS_ERR(name)) {
		ret = PTR_ERR(name);
		/* If there is no tag present, there is no exception callback */
		if (ret == -ENOENT)
			ret = 0;
		else if (ret == -EEXIST)
			verbose(env, "multiple exception callback tags for main subprog\n");
		return ret;
	}

	ret = btf_find_by_name_kind(btf, name, BTF_KIND_FUNC);
	if (ret < 0) {
		verbose(env, "exception callback '%s' could not be found in BTF\n", name);
		return ret;
	}
	id = ret;
	t = btf_type_by_id(btf, id);
	if (btf_func_linkage(t) != BTF_FUNC_GLOBAL) {
		verbose(env, "exception callback '%s' must have global linkage\n", name);
		return -EINVAL;
	}
	ret = 0;
	for (i = 0; i < aux->func_info_cnt; i++) {
		if (aux->func_info[i].type_id != id)
			continue;
		ret = aux->func_info[i].insn_off;
		/* Further func_info and subprog checks will also happen
		 * later, so assume this is the right insn_off for now.
		 */
		if (!ret) {
			verbose(env, "invalid exception callback insn_off in func_info: 0\n");
			ret = -EINVAL;
		}
	}
	if (!ret) {
		verbose(env, "exception callback type id not found in func_info\n");
		ret = -EINVAL;
	}
	return ret;
}

#define MAX_KFUNC_DESCS 256
#define MAX_KFUNC_BTFS	256

struct bpf_kfunc_desc {
	struct btf_func_model func_model;
	u32 func_id;
	s32 imm;
	u16 offset;
	unsigned long addr;
};

struct bpf_kfunc_btf {
	struct btf *btf;
	struct module *module;
	u16 offset;
};

struct bpf_kfunc_desc_tab {
	/* Sorted by func_id (BTF ID) and offset (fd_array offset) during
	 * verification. JITs do lookups by bpf_insn, where func_id may not be
	 * available, therefore at the end of verification do_misc_fixups()
	 * sorts this by imm and offset.
	 */
	struct bpf_kfunc_desc descs[MAX_KFUNC_DESCS];
	u32 nr_descs;
};

struct bpf_kfunc_btf_tab {
	struct bpf_kfunc_btf descs[MAX_KFUNC_BTFS];
	u32 nr_descs;
};

static int kfunc_desc_cmp_by_id_off(const void *a, const void *b)
{
	const struct bpf_kfunc_desc *d0 = a;
	const struct bpf_kfunc_desc *d1 = b;

	/* func_id is not greater than BTF_MAX_TYPE */
	return d0->func_id - d1->func_id ?: d0->offset - d1->offset;
}

static int kfunc_btf_cmp_by_off(const void *a, const void *b)
{
	const struct bpf_kfunc_btf *d0 = a;
	const struct bpf_kfunc_btf *d1 = b;

	return d0->offset - d1->offset;
}

static const struct bpf_kfunc_desc *
find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset)
{
	struct bpf_kfunc_desc desc = {
		.func_id = func_id,
		.offset = offset,
	};
	struct bpf_kfunc_desc_tab *tab;

	tab = prog->aux->kfunc_tab;
	return bsearch(&desc, tab->descs, tab->nr_descs,
		       sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off);
}

int bpf_get_kfunc_addr(const struct bpf_prog *prog, u32 func_id,
		       u16 btf_fd_idx, u8 **func_addr)
{
	const struct bpf_kfunc_desc *desc;

	desc = find_kfunc_desc(prog, func_id, btf_fd_idx);
	if (!desc)
		return -EFAULT;

	*func_addr = (u8 *)desc->addr;
	return 0;
}

static struct btf *__find_kfunc_desc_btf(struct bpf_verifier_env *env,
					 s16 offset)
{
	struct bpf_kfunc_btf kf_btf = { .offset = offset };
	struct bpf_kfunc_btf_tab *tab;
	struct bpf_kfunc_btf *b;
	struct module *mod;
	struct btf *btf;
	int btf_fd;

	tab = env->prog->aux->kfunc_btf_tab;
	b = bsearch(&kf_btf, tab->descs, tab->nr_descs,
		    sizeof(tab->descs[0]), kfunc_btf_cmp_by_off);
	if (!b) {
		if (tab->nr_descs == MAX_KFUNC_BTFS) {
			verbose(env, "too many different module BTFs\n");
			return ERR_PTR(-E2BIG);
		}

		if (bpfptr_is_null(env->fd_array)) {
			verbose(env, "kfunc offset > 0 without fd_array is invalid\n");
			return ERR_PTR(-EPROTO);
		}

		if (copy_from_bpfptr_offset(&btf_fd, env->fd_array,
					    offset * sizeof(btf_fd),
					    sizeof(btf_fd)))
			return ERR_PTR(-EFAULT);

		btf = btf_get_by_fd(btf_fd);
		if (IS_ERR(btf)) {
			verbose(env, "invalid module BTF fd specified\n");
			return btf;
		}

		if (!btf_is_module(btf)) {
			verbose(env, "BTF fd for kfunc is not a module BTF\n");
			btf_put(btf);
			return ERR_PTR(-EINVAL);
		}

		mod = btf_try_get_module(btf);
		if (!mod) {
			btf_put(btf);
			return ERR_PTR(-ENXIO);
		}

		b = &tab->descs[tab->nr_descs++];
		b->btf = btf;
		b->module = mod;
		b->offset = offset;

		/* sort() reorders entries by value, so b may no longer point
		 * to the right entry after this
		 */
		sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
		     kfunc_btf_cmp_by_off, NULL);
	} else {
		btf = b->btf;
	}

	return btf;
}

void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab)
{
	if (!tab)
		return;

	while (tab->nr_descs--) {
		module_put(tab->descs[tab->nr_descs].module);
		btf_put(tab->descs[tab->nr_descs].btf);
	}
	kfree(tab);
}

static struct btf *find_kfunc_desc_btf(struct bpf_verifier_env *env, s16 offset)
{
	if (offset) {
		if (offset < 0) {
			/* In the future, this can be allowed to increase limit
			 * of fd index into fd_array, interpreted as u16.
			 */
			verbose(env, "negative offset disallowed for kernel module function call\n");
			return ERR_PTR(-EINVAL);
		}

		return __find_kfunc_desc_btf(env, offset);
	}
	return btf_vmlinux ?: ERR_PTR(-ENOENT);
}

static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset)
{
	const struct btf_type *func, *func_proto;
	struct bpf_kfunc_btf_tab *btf_tab;
	struct bpf_kfunc_desc_tab *tab;
	struct bpf_prog_aux *prog_aux;
	struct bpf_kfunc_desc *desc;
	const char *func_name;
	struct btf *desc_btf;
	unsigned long call_imm;
	unsigned long addr;
	int err;

	prog_aux = env->prog->aux;
	tab = prog_aux->kfunc_tab;
	btf_tab = prog_aux->kfunc_btf_tab;
	if (!tab) {
		if (!btf_vmlinux) {
			verbose(env, "calling kernel function is not supported without CONFIG_DEBUG_INFO_BTF\n");
			return -ENOTSUPP;
		}

		if (!env->prog->jit_requested) {
			verbose(env, "JIT is required for calling kernel function\n");
			return -ENOTSUPP;
		}

		if (!bpf_jit_supports_kfunc_call()) {
			verbose(env, "JIT does not support calling kernel function\n");
			return -ENOTSUPP;
		}

		if (!env->prog->gpl_compatible) {
			verbose(env, "cannot call kernel function from non-GPL compatible program\n");
			return -EINVAL;
		}

		tab = kzalloc(sizeof(*tab), GFP_KERNEL);
		if (!tab)
			return -ENOMEM;
		prog_aux->kfunc_tab = tab;
	}

	/* func_id == 0 is always invalid, but instead of returning an error, be
	 * conservative and wait until the code elimination pass before returning
	 * error, so that invalid calls that get pruned out can be in BPF programs
	 * loaded from userspace.  It is also required that offset be untouched
	 * for such calls.
	 */
	if (!func_id && !offset)
		return 0;

	if (!btf_tab && offset) {
		btf_tab = kzalloc(sizeof(*btf_tab), GFP_KERNEL);
		if (!btf_tab)
			return -ENOMEM;
		prog_aux->kfunc_btf_tab = btf_tab;
	}

	desc_btf = find_kfunc_desc_btf(env, offset);
	if (IS_ERR(desc_btf)) {
		verbose(env, "failed to find BTF for kernel function\n");
		return PTR_ERR(desc_btf);
	}

	if (find_kfunc_desc(env->prog, func_id, offset))
		return 0;

	if (tab->nr_descs == MAX_KFUNC_DESCS) {
		verbose(env, "too many different kernel function calls\n");
		return -E2BIG;
	}

	func = btf_type_by_id(desc_btf, func_id);
	if (!func || !btf_type_is_func(func)) {
		verbose(env, "kernel btf_id %u is not a function\n",
			func_id);
		return -EINVAL;
	}
	func_proto = btf_type_by_id(desc_btf, func->type);
	if (!func_proto || !btf_type_is_func_proto(func_proto)) {
		verbose(env, "kernel function btf_id %u does not have a valid func_proto\n",
			func_id);
		return -EINVAL;
	}

	func_name = btf_name_by_offset(desc_btf, func->name_off);
	addr = kallsyms_lookup_name(func_name);
	if (!addr) {
		verbose(env, "cannot find address for kernel function %s\n",
			func_name);
		return -EINVAL;
	}
	specialize_kfunc(env, func_id, offset, &addr);

	if (bpf_jit_supports_far_kfunc_call()) {
		call_imm = func_id;
	} else {
		call_imm = BPF_CALL_IMM(addr);
		/* Check whether the relative offset overflows desc->imm */
		if ((unsigned long)(s32)call_imm != call_imm) {
			verbose(env, "address of kernel function %s is out of range\n",
				func_name);
			return -EINVAL;
		}
	}

	if (bpf_dev_bound_kfunc_id(func_id)) {
		err = bpf_dev_bound_kfunc_check(&env->log, prog_aux);
		if (err)
			return err;
	}

	desc = &tab->descs[tab->nr_descs++];
	desc->func_id = func_id;
	desc->imm = call_imm;
	desc->offset = offset;
	desc->addr = addr;
	err = btf_distill_func_proto(&env->log, desc_btf,
				     func_proto, func_name,
				     &desc->func_model);
	if (!err)
		sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
		     kfunc_desc_cmp_by_id_off, NULL);
	return err;
}

static int kfunc_desc_cmp_by_imm_off(const void *a, const void *b)
{
	const struct bpf_kfunc_desc *d0 = a;
	const struct bpf_kfunc_desc *d1 = b;

	if (d0->imm != d1->imm)
		return d0->imm < d1->imm ? -1 : 1;
	if (d0->offset != d1->offset)
		return d0->offset < d1->offset ? -1 : 1;
	return 0;
}

static void sort_kfunc_descs_by_imm_off(struct bpf_prog *prog)
{
	struct bpf_kfunc_desc_tab *tab;

	tab = prog->aux->kfunc_tab;
	if (!tab)
		return;

	sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]),
	     kfunc_desc_cmp_by_imm_off, NULL);
}

bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog)
{
	return !!prog->aux->kfunc_tab;
}

const struct btf_func_model *
bpf_jit_find_kfunc_model(const struct bpf_prog *prog,
			 const struct bpf_insn *insn)
{
	const struct bpf_kfunc_desc desc = {
		.imm = insn->imm,
		.offset = insn->off,
	};
	const struct bpf_kfunc_desc *res;
	struct bpf_kfunc_desc_tab *tab;

	tab = prog->aux->kfunc_tab;
	res = bsearch(&desc, tab->descs, tab->nr_descs,
		      sizeof(tab->descs[0]), kfunc_desc_cmp_by_imm_off);

	return res ? &res->func_model : NULL;
}

static int add_subprog_and_kfunc(struct bpf_verifier_env *env)
{
	struct bpf_subprog_info *subprog = env->subprog_info;
	int i, ret, insn_cnt = env->prog->len, ex_cb_insn;
	struct bpf_insn *insn = env->prog->insnsi;

	/* Add entry function. */
	ret = add_subprog(env, 0);
	if (ret)
		return ret;

	for (i = 0; i < insn_cnt; i++, insn++) {
		if (!bpf_pseudo_func(insn) && !bpf_pseudo_call(insn) &&
		    !bpf_pseudo_kfunc_call(insn))
			continue;

		if (!env->bpf_capable) {
			verbose(env, "loading/calling other bpf or kernel functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n");
			return -EPERM;
		}

		if (bpf_pseudo_func(insn) || bpf_pseudo_call(insn))
			ret = add_subprog(env, i + insn->imm + 1);
		else
			ret = add_kfunc_call(env, insn->imm, insn->off);

		if (ret < 0)
			return ret;
	}

	ret = bpf_find_exception_callback_insn_off(env);
	if (ret < 0)
		return ret;
	ex_cb_insn = ret;

	/* If ex_cb_insn > 0, this means that the main program has a subprog
	 * marked using BTF decl tag to serve as the exception callback.
	 */
	if (ex_cb_insn) {
		ret = add_subprog(env, ex_cb_insn);
		if (ret < 0)
			return ret;
		for (i = 1; i < env->subprog_cnt; i++) {
			if (env->subprog_info[i].start != ex_cb_insn)
				continue;
			env->exception_callback_subprog = i;
			mark_subprog_exc_cb(env, i);
			break;
		}
	}

	/* Add a fake 'exit' subprog which could simplify subprog iteration
	 * logic. 'subprog_cnt' should not be increased.
	 */
	subprog[env->subprog_cnt].start = insn_cnt;

	if (env->log.level & BPF_LOG_LEVEL2)
		for (i = 0; i < env->subprog_cnt; i++)
			verbose(env, "func#%d @%d\n", i, subprog[i].start);

	return 0;
}

static int check_subprogs(struct bpf_verifier_env *env)
{
	int i, subprog_start, subprog_end, off, cur_subprog = 0;
	struct bpf_subprog_info *subprog = env->subprog_info;
	struct bpf_insn *insn = env->prog->insnsi;
	int insn_cnt = env->prog->len;

	/* now check that all jumps are within the same subprog */
	subprog_start = subprog[cur_subprog].start;
	subprog_end = subprog[cur_subprog + 1].start;
	for (i = 0; i < insn_cnt; i++) {
		u8 code = insn[i].code;

		if (code == (BPF_JMP | BPF_CALL) &&
		    insn[i].src_reg == 0 &&
		    insn[i].imm == BPF_FUNC_tail_call) {
			subprog[cur_subprog].has_tail_call = true;
			subprog[cur_subprog].tail_call_reachable = true;
		}
		if (BPF_CLASS(code) == BPF_LD &&
		    (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND))
			subprog[cur_subprog].has_ld_abs = true;
		if (BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32)
			goto next;
		if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL)
			goto next;
		if (code == (BPF_JMP32 | BPF_JA))
			off = i + insn[i].imm + 1;
		else
			off = i + insn[i].off + 1;
		if (off < subprog_start || off >= subprog_end) {
			verbose(env, "jump out of range from insn %d to %d\n", i, off);
			return -EINVAL;
		}
next:
		if (i == subprog_end - 1) {
			/* to avoid fall-through from one subprog into another
			 * the last insn of the subprog should be either exit
			 * or unconditional jump back or bpf_throw call
			 */
			if (code != (BPF_JMP | BPF_EXIT) &&
			    code != (BPF_JMP32 | BPF_JA) &&
			    code != (BPF_JMP | BPF_JA)) {
				verbose(env, "last insn is not an exit or jmp\n");
				return -EINVAL;
			}
			subprog_start = subprog_end;
			cur_subprog++;
			if (cur_subprog < env->subprog_cnt)
				subprog_end = subprog[cur_subprog + 1].start;
		}
	}
	return 0;
}

/* Parentage chain of this register (or stack slot) should take care of all
 * issues like callee-saved registers, stack slot allocation time, etc.
 */
static int mark_reg_read(struct bpf_verifier_env *env,
			 const struct bpf_reg_state *state,
			 struct bpf_reg_state *parent, u8 flag)
{
	bool writes = parent == state->parent; /* Observe write marks */
	int cnt = 0;

	while (parent) {
		/* if read wasn't screened by an earlier write ... */
		if (writes && state->live & REG_LIVE_WRITTEN)
			break;
		if (parent->live & REG_LIVE_DONE) {
			verbose(env, "verifier BUG type %s var_off %lld off %d\n",
				reg_type_str(env, parent->type),
				parent->var_off.value, parent->off);
			return -EFAULT;
		}
		/* The first condition is more likely to be true than the
		 * second, checked it first.
		 */
		if ((parent->live & REG_LIVE_READ) == flag ||
		    parent->live & REG_LIVE_READ64)
			/* The parentage chain never changes and
			 * this parent was already marked as LIVE_READ.
			 * There is no need to keep walking the chain again and
			 * keep re-marking all parents as LIVE_READ.
			 * This case happens when the same register is read
			 * multiple times without writes into it in-between.
			 * Also, if parent has the stronger REG_LIVE_READ64 set,
			 * then no need to set the weak REG_LIVE_READ32.
			 */
			break;
		/* ... then we depend on parent's value */
		parent->live |= flag;
		/* REG_LIVE_READ64 overrides REG_LIVE_READ32. */
		if (flag == REG_LIVE_READ64)
			parent->live &= ~REG_LIVE_READ32;
		state = parent;
		parent = state->parent;
		writes = true;
		cnt++;
	}

	if (env->longest_mark_read_walk < cnt)
		env->longest_mark_read_walk = cnt;
	return 0;
}

static int mark_dynptr_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
	struct bpf_func_state *state = func(env, reg);
	int spi, ret;

	/* For CONST_PTR_TO_DYNPTR, it must have already been done by
	 * check_reg_arg in check_helper_call and mark_btf_func_reg_size in
	 * check_kfunc_call.
	 */
	if (reg->type == CONST_PTR_TO_DYNPTR)
		return 0;
	spi = dynptr_get_spi(env, reg);
	if (spi < 0)
		return spi;
	/* Caller ensures dynptr is valid and initialized, which means spi is in
	 * bounds and spi is the first dynptr slot. Simply mark stack slot as
	 * read.
	 */
	ret = mark_reg_read(env, &state->stack[spi].spilled_ptr,
			    state->stack[spi].spilled_ptr.parent, REG_LIVE_READ64);
	if (ret)
		return ret;
	return mark_reg_read(env, &state->stack[spi - 1].spilled_ptr,
			     state->stack[spi - 1].spilled_ptr.parent, REG_LIVE_READ64);
}

static int mark_iter_read(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
			  int spi, int nr_slots)
{
	struct bpf_func_state *state = func(env, reg);
	int err, i;

	for (i = 0; i < nr_slots; i++) {
		struct bpf_reg_state *st = &state->stack[spi - i].spilled_ptr;

		err = mark_reg_read(env, st, st->parent, REG_LIVE_READ64);
		if (err)
			return err;

		mark_stack_slot_scratched(env, spi - i);
	}

	return 0;
}

/* This function is supposed to be used by the following 32-bit optimization
 * code only. It returns TRUE if the source or destination register operates
 * on 64-bit, otherwise return FALSE.
 */
static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn,
		     u32 regno, struct bpf_reg_state *reg, enum reg_arg_type t)
{
	u8 code, class, op;

	code = insn->code;
	class = BPF_CLASS(code);
	op = BPF_OP(code);
	if (class == BPF_JMP) {
		/* BPF_EXIT for "main" will reach here. Return TRUE
		 * conservatively.
		 */
		if (op == BPF_EXIT)
			return true;
		if (op == BPF_CALL) {
			/* BPF to BPF call will reach here because of marking
			 * caller saved clobber with DST_OP_NO_MARK for which we
			 * don't care the register def because they are anyway
			 * marked as NOT_INIT already.
			 */
			if (insn->src_reg == BPF_PSEUDO_CALL)
				return false;
			/* Helper call will reach here because of arg type
			 * check, conservatively return TRUE.
			 */
			if (t == SRC_OP)
				return true;

			return false;
		}
	}

	if (class == BPF_ALU64 && op == BPF_END && (insn->imm == 16 || insn->imm == 32))
		return false;

	if (class == BPF_ALU64 || class == BPF_JMP ||
	    (class == BPF_ALU && op == BPF_END && insn->imm == 64))
		return true;

	if (class == BPF_ALU || class == BPF_JMP32)
		return false;

	if (class == BPF_LDX) {
		if (t != SRC_OP)
			return BPF_SIZE(code) == BPF_DW || BPF_MODE(code) == BPF_MEMSX;
		/* LDX source must be ptr. */
		return true;
	}

	if (class == BPF_STX) {
		/* BPF_STX (including atomic variants) has multiple source
		 * operands, one of which is a ptr. Check whether the caller is
		 * asking about it.
		 */
		if (t == SRC_OP && reg->type != SCALAR_VALUE)
			return true;
		return BPF_SIZE(code) == BPF_DW;
	}

	if (class == BPF_LD) {
		u8 mode = BPF_MODE(code);

		/* LD_IMM64 */
		if (mode == BPF_IMM)
			return true;

		/* Both LD_IND and LD_ABS return 32-bit data. */
		if (t != SRC_OP)
			return  false;

		/* Implicit ctx ptr. */
		if (regno == BPF_REG_6)
			return true;

		/* Explicit source could be any width. */
		return true;
	}

	if (class == BPF_ST)
		/* The only source register for BPF_ST is a ptr. */
		return true;

	/* Conservatively return true at default. */
	return true;
}

/* Return the regno defined by the insn, or -1. */
static int insn_def_regno(const struct bpf_insn *insn)
{
	switch (BPF_CLASS(insn->code)) {
	case BPF_JMP:
	case BPF_JMP32:
	case BPF_ST:
		return -1;
	case BPF_STX:
		if ((BPF_MODE(insn->code) == BPF_ATOMIC ||
		     BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) &&
		    (insn->imm & BPF_FETCH)) {
			if (insn->imm == BPF_CMPXCHG)
				return BPF_REG_0;
			else
				return insn->src_reg;
		} else {
			return -1;
		}
	default:
		return insn->dst_reg;
	}
}

/* Return TRUE if INSN has defined any 32-bit value explicitly. */
static bool insn_has_def32(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
	int dst_reg = insn_def_regno(insn);

	if (dst_reg == -1)
		return false;

	return !is_reg64(env, insn, dst_reg, NULL, DST_OP);
}

static void mark_insn_zext(struct bpf_verifier_env *env,
			   struct bpf_reg_state *reg)
{
	s32 def_idx = reg->subreg_def;

	if (def_idx == DEF_NOT_SUBREG)
		return;

	env->insn_aux_data[def_idx - 1].zext_dst = true;
	/* The dst will be zero extended, so won't be sub-register anymore. */
	reg->subreg_def = DEF_NOT_SUBREG;
}

static int __check_reg_arg(struct bpf_verifier_env *env, struct bpf_reg_state *regs, u32 regno,
			   enum reg_arg_type t)
{
	struct bpf_insn *insn = env->prog->insnsi + env->insn_idx;
	struct bpf_reg_state *reg;
	bool rw64;

	if (regno >= MAX_BPF_REG) {
		verbose(env, "R%d is invalid\n", regno);
		return -EINVAL;
	}

	mark_reg_scratched(env, regno);

	reg = &regs[regno];
	rw64 = is_reg64(env, insn, regno, reg, t);
	if (t == SRC_OP) {
		/* check whether register used as source operand can be read */
		if (reg->type == NOT_INIT) {
			verbose(env, "R%d !read_ok\n", regno);
			return -EACCES;
		}
		/* We don't need to worry about FP liveness because it's read-only */
		if (regno == BPF_REG_FP)
			return 0;

		if (rw64)
			mark_insn_zext(env, reg);

		return mark_reg_read(env, reg, reg->parent,
				     rw64 ? REG_LIVE_READ64 : REG_LIVE_READ32);
	} else {
		/* check whether register used as dest operand can be written to */
		if (regno == BPF_REG_FP) {
			verbose(env, "frame pointer is read only\n");
			return -EACCES;
		}
		reg->live |= REG_LIVE_WRITTEN;
		reg->subreg_def = rw64 ? DEF_NOT_SUBREG : env->insn_idx + 1;
		if (t == DST_OP)
			mark_reg_unknown(env, regs, regno);
	}
	return 0;
}

static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
			 enum reg_arg_type t)
{
	struct bpf_verifier_state *vstate = env->cur_state;
	struct bpf_func_state *state = vstate->frame[vstate->curframe];

	return __check_reg_arg(env, state->regs, regno, t);
}

static int insn_stack_access_flags(int frameno, int spi)
{
	return INSN_F_STACK_ACCESS | (spi << INSN_F_SPI_SHIFT) | frameno;
}

static int insn_stack_access_spi(int insn_flags)
{
	return (insn_flags >> INSN_F_SPI_SHIFT) & INSN_F_SPI_MASK;
}

static int insn_stack_access_frameno(int insn_flags)
{
	return insn_flags & INSN_F_FRAMENO_MASK;
}

static void mark_jmp_point(struct bpf_verifier_env *env, int idx)
{
	env->insn_aux_data[idx].jmp_point = true;
}

static bool is_jmp_point(struct bpf_verifier_env *env, int insn_idx)
{
	return env->insn_aux_data[insn_idx].jmp_point;
}

#define LR_FRAMENO_BITS	3
#define LR_SPI_BITS	6
#define LR_ENTRY_BITS	(LR_SPI_BITS + LR_FRAMENO_BITS + 1)
#define LR_SIZE_BITS	4
#define LR_FRAMENO_MASK	((1ull << LR_FRAMENO_BITS) - 1)
#define LR_SPI_MASK	((1ull << LR_SPI_BITS)     - 1)
#define LR_SIZE_MASK	((1ull << LR_SIZE_BITS)    - 1)
#define LR_SPI_OFF	LR_FRAMENO_BITS
#define LR_IS_REG_OFF	(LR_SPI_BITS + LR_FRAMENO_BITS)
#define LINKED_REGS_MAX	6

struct linked_reg {
	u8 frameno;
	union {
		u8 spi;
		u8 regno;
	};
	bool is_reg;
};

struct linked_regs {
	int cnt;
	struct linked_reg entries[LINKED_REGS_MAX];
};

static struct linked_reg *linked_regs_push(struct linked_regs *s)
{
	if (s->cnt < LINKED_REGS_MAX)
		return &s->entries[s->cnt++];

	return NULL;
}

/* Use u64 as a vector of 6 10-bit values, use first 4-bits to track
 * number of elements currently in stack.
 * Pack one history entry for linked registers as 10 bits in the following format:
 * - 3-bits frameno
 * - 6-bits spi_or_reg
 * - 1-bit  is_reg
 */
static u64 linked_regs_pack(struct linked_regs *s)
{
	u64 val = 0;
	int i;

	for (i = 0; i < s->cnt; ++i) {
		struct linked_reg *e = &s->entries[i];
		u64 tmp = 0;

		tmp |= e->frameno;
		tmp |= e->spi << LR_SPI_OFF;
		tmp |= (e->is_reg ? 1 : 0) << LR_IS_REG_OFF;

		val <<= LR_ENTRY_BITS;
		val |= tmp;
	}
	val <<= LR_SIZE_BITS;
	val |= s->cnt;
	return val;
}

static void linked_regs_unpack(u64 val, struct linked_regs *s)
{
	int i;

	s->cnt = val & LR_SIZE_MASK;
	val >>= LR_SIZE_BITS;

	for (i = 0; i < s->cnt; ++i) {
		struct linked_reg *e = &s->entries[i];

		e->frameno =  val & LR_FRAMENO_MASK;
		e->spi     = (val >> LR_SPI_OFF) & LR_SPI_MASK;
		e->is_reg  = (val >> LR_IS_REG_OFF) & 0x1;
		val >>= LR_ENTRY_BITS;
	}
}

/* for any branch, call, exit record the history of jmps in the given state */
static int push_jmp_history(struct bpf_verifier_env *env, struct bpf_verifier_state *cur,
			    int insn_flags, u64 linked_regs)
{
	u32 cnt = cur->jmp_history_cnt;
	struct bpf_jmp_history_entry *p;
	size_t alloc_size;

	/* combine instruction flags if we already recorded this instruction */
	if (env->cur_hist_ent) {
		/* atomic instructions push insn_flags twice, for READ and
		 * WRITE sides, but they should agree on stack slot
		 */
		WARN_ONCE((env->cur_hist_ent->flags & insn_flags) &&
			  (env->cur_hist_ent->flags & insn_flags) != insn_flags,
			  "verifier insn history bug: insn_idx %d cur flags %x new flags %x\n",
			  env->insn_idx, env->cur_hist_ent->flags, insn_flags);
		env->cur_hist_ent->flags |= insn_flags;
		WARN_ONCE(env->cur_hist_ent->linked_regs != 0,
			  "verifier insn history bug: insn_idx %d linked_regs != 0: %#llx\n",
			  env->insn_idx, env->cur_hist_ent->linked_regs);
		env->cur_hist_ent->linked_regs = linked_regs;
		return 0;
	}

	cnt++;
	alloc_size = kmalloc_size_roundup(size_mul(cnt, sizeof(*p)));
	p = krealloc(cur->jmp_history, alloc_size, GFP_USER);
	if (!p)
		return -ENOMEM;
	cur->jmp_history = p;

	p = &cur->jmp_history[cnt - 1];
	p->idx = env->insn_idx;
	p->prev_idx = env->prev_insn_idx;
	p->flags = insn_flags;
	p->linked_regs = linked_regs;
	cur->jmp_history_cnt = cnt;
	env->cur_hist_ent = p;

	return 0;
}

static struct bpf_jmp_history_entry *get_jmp_hist_entry(struct bpf_verifier_state *st,
						        u32 hist_end, int insn_idx)
{
	if (hist_end > 0 && st->jmp_history[hist_end - 1].idx == insn_idx)
		return &st->jmp_history[hist_end - 1];
	return NULL;
}

/* Backtrack one insn at a time. If idx is not at the top of recorded
 * history then previous instruction came from straight line execution.
 * Return -ENOENT if we exhausted all instructions within given state.
 *
 * It's legal to have a bit of a looping with the same starting and ending
 * insn index within the same state, e.g.: 3->4->5->3, so just because current
 * instruction index is the same as state's first_idx doesn't mean we are
 * done. If there is still some jump history left, we should keep going. We
 * need to take into account that we might have a jump history between given
 * state's parent and itself, due to checkpointing. In this case, we'll have
 * history entry recording a jump from last instruction of parent state and
 * first instruction of given state.
 */
static int get_prev_insn_idx(struct bpf_verifier_state *st, int i,
			     u32 *history)
{
	u32 cnt = *history;

	if (i == st->first_insn_idx) {
		if (cnt == 0)
			return -ENOENT;
		if (cnt == 1 && st->jmp_history[0].idx == i)
			return -ENOENT;
	}

	if (cnt && st->jmp_history[cnt - 1].idx == i) {
		i = st->jmp_history[cnt - 1].prev_idx;
		(*history)--;
	} else {
		i--;
	}
	return i;
}

static const char *disasm_kfunc_name(void *data, const struct bpf_insn *insn)
{
	const struct btf_type *func;
	struct btf *desc_btf;

	if (insn->src_reg != BPF_PSEUDO_KFUNC_CALL)
		return NULL;

	desc_btf = find_kfunc_desc_btf(data, insn->off);
	if (IS_ERR(desc_btf))
		return "<error>";

	func = btf_type_by_id(desc_btf, insn->imm);
	return btf_name_by_offset(desc_btf, func->name_off);
}

static inline void bt_init(struct backtrack_state *bt, u32 frame)
{
	bt->frame = frame;
}

static inline void bt_reset(struct backtrack_state *bt)
{
	struct bpf_verifier_env *env = bt->env;

	memset(bt, 0, sizeof(*bt));
	bt->env = env;
}

static inline u32 bt_empty(struct backtrack_state *bt)
{
	u64 mask = 0;
	int i;

	for (i = 0; i <= bt->frame; i++)
		mask |= bt->reg_masks[i] | bt->stack_masks[i];

	return mask == 0;
}

static inline int bt_subprog_enter(struct backtrack_state *bt)
{
	if (bt->frame == MAX_CALL_FRAMES - 1) {
		verbose(bt->env, "BUG subprog enter from frame %d\n", bt->frame);
		WARN_ONCE(1, "verifier backtracking bug");
		return -EFAULT;
	}
	bt->frame++;
	return 0;
}

static inline int bt_subprog_exit(struct backtrack_state *bt)
{
	if (bt->frame == 0) {
		verbose(bt->env, "BUG subprog exit from frame 0\n");
		WARN_ONCE(1, "verifier backtracking bug");
		return -EFAULT;
	}
	bt->frame--;
	return 0;
}

static inline void bt_set_frame_reg(struct backtrack_state *bt, u32 frame, u32 reg)
{
	bt->reg_masks[frame] |= 1 << reg;
}

static inline void bt_clear_frame_reg(struct backtrack_state *bt, u32 frame, u32 reg)
{
	bt->reg_masks[frame] &= ~(1 << reg);
}

static inline void bt_set_reg(struct backtrack_state *bt, u32 reg)
{
	bt_set_frame_reg(bt, bt->frame, reg);
}

static inline void bt_clear_reg(struct backtrack_state *bt, u32 reg)
{
	bt_clear_frame_reg(bt, bt->frame, reg);
}

static inline void bt_set_frame_slot(struct backtrack_state *bt, u32 frame, u32 slot)
{
	bt->stack_masks[frame] |= 1ull << slot;
}

static inline void bt_clear_frame_slot(struct backtrack_state *bt, u32 frame, u32 slot)
{
	bt->stack_masks[frame] &= ~(1ull << slot);
}

static inline u32 bt_frame_reg_mask(struct backtrack_state *bt, u32 frame)
{
	return bt->reg_masks[frame];
}

static inline u32 bt_reg_mask(struct backtrack_state *bt)
{
	return bt->reg_masks[bt->frame];
}

static inline u64 bt_frame_stack_mask(struct backtrack_state *bt, u32 frame)
{
	return bt->stack_masks[frame];
}

static inline u64 bt_stack_mask(struct backtrack_state *bt)
{
	return bt->stack_masks[bt->frame];
}

static inline bool bt_is_reg_set(struct backtrack_state *bt, u32 reg)
{
	return bt->reg_masks[bt->frame] & (1 << reg);
}

static inline bool bt_is_frame_reg_set(struct backtrack_state *bt, u32 frame, u32 reg)
{
	return bt->reg_masks[frame] & (1 << reg);
}

static inline bool bt_is_frame_slot_set(struct backtrack_state *bt, u32 frame, u32 slot)
{
	return bt->stack_masks[frame] & (1ull << slot);
}

/* format registers bitmask, e.g., "r0,r2,r4" for 0x15 mask */
static void fmt_reg_mask(char *buf, ssize_t buf_sz, u32 reg_mask)
{
	DECLARE_BITMAP(mask, 64);
	bool first = true;
	int i, n;

	buf[0] = '\0';

	bitmap_from_u64(mask, reg_mask);
	for_each_set_bit(i, mask, 32) {
		n = snprintf(buf, buf_sz, "%sr%d", first ? "" : ",", i);
		first = false;
		buf += n;
		buf_sz -= n;
		if (buf_sz < 0)
			break;
	}
}
/* format stack slots bitmask, e.g., "-8,-24,-40" for 0x15 mask */
static void fmt_stack_mask(char *buf, ssize_t buf_sz, u64 stack_mask)
{
	DECLARE_BITMAP(mask, 64);
	bool first = true;
	int i, n;

	buf[0] = '\0';

	bitmap_from_u64(mask, stack_mask);
	for_each_set_bit(i, mask, 64) {
		n = snprintf(buf, buf_sz, "%s%d", first ? "" : ",", -(i + 1) * 8);
		first = false;
		buf += n;
		buf_sz -= n;
		if (buf_sz < 0)
			break;
	}
}

/* If any register R in hist->linked_regs is marked as precise in bt,
 * do bt_set_frame_{reg,slot}(bt, R) for all registers in hist->linked_regs.
 */
static void bt_sync_linked_regs(struct backtrack_state *bt, struct bpf_jmp_history_entry *hist)
{
	struct linked_regs linked_regs;
	bool some_precise = false;
	int i;

	if (!hist || hist->linked_regs == 0)
		return;

	linked_regs_unpack(hist->linked_regs, &linked_regs);
	for (i = 0; i < linked_regs.cnt; ++i) {
		struct linked_reg *e = &linked_regs.entries[i];

		if ((e->is_reg && bt_is_frame_reg_set(bt, e->frameno, e->regno)) ||
		    (!e->is_reg && bt_is_frame_slot_set(bt, e->frameno, e->spi))) {
			some_precise = true;
			break;
		}
	}

	if (!some_precise)
		return;

	for (i = 0; i < linked_regs.cnt; ++i) {
		struct linked_reg *e = &linked_regs.entries[i];

		if (e->is_reg)
			bt_set_frame_reg(bt, e->frameno, e->regno);
		else
			bt_set_frame_slot(bt, e->frameno, e->spi);
	}
}

static bool calls_callback(struct bpf_verifier_env *env, int insn_idx);

/* For given verifier state backtrack_insn() is called from the last insn to
 * the first insn. Its purpose is to compute a bitmask of registers and
 * stack slots that needs precision in the parent verifier state.
 *
 * @idx is an index of the instruction we are currently processing;
 * @subseq_idx is an index of the subsequent instruction that:
 *   - *would be* executed next, if jump history is viewed in forward order;
 *   - *was* processed previously during backtracking.
 */
static int backtrack_insn(struct bpf_verifier_env *env, int idx, int subseq_idx,
			  struct bpf_jmp_history_entry *hist, struct backtrack_state *bt)
{
	const struct bpf_insn_cbs cbs = {
		.cb_call	= disasm_kfunc_name,
		.cb_print	= verbose,
		.private_data	= env,
	};
	struct bpf_insn *insn = env->prog->insnsi + idx;
	u8 class = BPF_CLASS(insn->code);
	u8 opcode = BPF_OP(insn->code);
	u8 mode = BPF_MODE(insn->code);
	u32 dreg = insn->dst_reg;
	u32 sreg = insn->src_reg;
	u32 spi, i, fr;

	if (insn->code == 0)
		return 0;
	if (env->log.level & BPF_LOG_LEVEL2) {
		fmt_reg_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_reg_mask(bt));
		verbose(env, "mark_precise: frame%d: regs=%s ",
			bt->frame, env->tmp_str_buf);
		fmt_stack_mask(env->tmp_str_buf, TMP_STR_BUF_LEN, bt_stack_mask(bt));
		verbose(env, "stack=%s before ", env->tmp_str_buf);
		verbose(env, "%d: ", idx);
		print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
	}

	/* If there is a history record that some registers gained range at this insn,
	 * propagate precision marks to those registers, so that bt_is_reg_set()
	 * accounts for these registers.
	 */
	bt_sync_linked_regs(bt, hist);

	if (class == BPF_ALU || class == BPF_ALU64) {
		if (!bt_is_reg_set(bt, dreg))
			return 0;
		if (opcode == BPF_END || opcode == BPF_NEG) {
			/* sreg is reserved and unused
			 * dreg still need precision before this insn
			 */
			return 0;
		} else if (opcode == BPF_MOV) {
			if (BPF_SRC(insn->code) == BPF_X) {
				/* dreg = sreg or dreg = (s8, s16, s32)sreg
				 * dreg needs precision after this insn
				 * sreg needs precision before this insn
				 */
				bt_clear_reg(bt, dreg);
				if (sreg != BPF_REG_FP)
					bt_set_reg(bt, sreg);
			} else {
				/* dreg = K
				 * dreg needs precision after this insn.
				 * Corresponding register is already marked
				 * as precise=true in this verifier state.
				 * No further markings in parent are necessary
				 */
				bt_clear_reg(bt, dreg);
			}
		} else {
			if (BPF_SRC(insn->code) == BPF_X) {
				/* dreg += sreg
				 * both dreg and sreg need precision
				 * before this insn
				 */
				if (sreg != BPF_REG_FP)
					bt_set_reg(bt, sreg);
			} /* else dreg += K
			   * dreg still needs precision before this insn
			   */
		}
	} else if (class == BPF_LDX) {
		if (!bt_is_reg_set(bt, dreg))
			return 0;
		bt_clear_reg(bt, dreg);

		/* scalars can only be spilled into stack w/o losing precision.
		 * Load from any other memory can be zero extended.
		 * The desire to keep that precision is already indicated
		 * by 'precise' mark in corresponding register of this state.
		 * No further tracking necessary.
		 */
		if (!hist || !(hist->flags & INSN_F_STACK_ACCESS))
			return 0;
		/* dreg = *(u64 *)[fp - off] was a fill from the stack.
		 * that [fp - off] slot contains scalar that needs to be
		 * tracked with precision
		 */
		spi = insn_stack_access_spi(hist->flags);
		fr = insn_stack_access_frameno(hist->flags);
		bt_set_frame_slot(bt, fr, spi);
	} else if (class == BPF_STX || class == BPF_ST) {
		if (bt_is_reg_set(bt, dreg))
			/* stx & st shouldn't be using _scalar_ dst_reg
			 * to access memory. It means backtracking
			 * encountered a case of pointer subtraction.
			 */
			return -ENOTSUPP;
		/* scalars can only be spilled into stack */
		if (!hist || !(hist->flags & INSN_F_STACK_ACCESS))
			return 0;
		spi = insn_stack_access_spi(hist->flags);
		fr = insn_stack_access_frameno(hist->flags);
		if (!bt_is_frame_slot_set(bt, fr, spi))
			return 0;
		bt_clear_frame_slot(bt, fr, spi);
		if (class == BPF_STX)
			bt_set_reg(bt, sreg);
	} else if (class == BPF_JMP || class == BPF_JMP32) {
		if (bpf_pseudo_call(insn)) {
			int subprog_insn_idx, subprog;

			subprog_insn_idx = idx + insn->imm + 1;
			subprog = find_subprog(env, subprog_insn_idx);
			if (subprog < 0)
				return -EFAULT;

			if (subprog_is_global(env, subprog)) {
				/* check that jump history doesn't have any
				 * extra instructions from subprog; the next
				 * instruction after call to global subprog
				 * should be literally next instruction in
				 * caller program
				 */
				WARN_ONCE(idx + 1 != subseq_idx, "verifier backtracking bug");
				/* r1-r5 are invalidated after subprog call,
				 * so for global func call it shouldn't be set
				 * anymore
				 */
				if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) {
					verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
					WARN_ONCE(1, "verifier backtracking bug");
					return -EFAULT;
				}
				/* global subprog always sets R0 */
				bt_clear_reg(bt, BPF_REG_0);
				return 0;
			} else {
				/* static subprog call instruction, which
				 * means that we are exiting current subprog,
				 * so only r1-r5 could be still requested as
				 * precise, r0 and r6-r10 or any stack slot in
				 * the current frame should be zero by now
				 */
				if (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) {
					verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
					WARN_ONCE(1, "verifier backtracking bug");
					return -EFAULT;
				}
				/* we are now tracking register spills correctly,
				 * so any instance of leftover slots is a bug
				 */
				if (bt_stack_mask(bt) != 0) {
					verbose(env, "BUG stack slots %llx\n", bt_stack_mask(bt));
					WARN_ONCE(1, "verifier backtracking bug (subprog leftover stack slots)");
					return -EFAULT;
				}
				/* propagate r1-r5 to the caller */
				for (i = BPF_REG_1; i <= BPF_REG_5; i++) {
					if (bt_is_reg_set(bt, i)) {
						bt_clear_reg(bt, i);
						bt_set_frame_reg(bt, bt->frame - 1, i);
					}
				}
				if (bt_subprog_exit(bt))
					return -EFAULT;
				return 0;
			}
		} else if (is_sync_callback_calling_insn(insn) && idx != subseq_idx - 1) {
			/* exit from callback subprog to callback-calling helper or
			 * kfunc call. Use idx/subseq_idx check to discern it from
			 * straight line code backtracking.
			 * Unlike the subprog call handling above, we shouldn't
			 * propagate precision of r1-r5 (if any requested), as they are
			 * not actually arguments passed directly to callback subprogs
			 */
			if (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) {
				verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
				WARN_ONCE(1, "verifier backtracking bug");
				return -EFAULT;
			}
			if (bt_stack_mask(bt) != 0) {
				verbose(env, "BUG stack slots %llx\n", bt_stack_mask(bt));
				WARN_ONCE(1, "verifier backtracking bug (callback leftover stack slots)");
				return -EFAULT;
			}
			/* clear r1-r5 in callback subprog's mask */
			for (i = BPF_REG_1; i <= BPF_REG_5; i++)
				bt_clear_reg(bt, i);
			if (bt_subprog_exit(bt))
				return -EFAULT;
			return 0;
		} else if (opcode == BPF_CALL) {
			/* kfunc with imm==0 is invalid and fixup_kfunc_call will
			 * catch this error later. Make backtracking conservative
			 * with ENOTSUPP.
			 */
			if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL && insn->imm == 0)
				return -ENOTSUPP;
			/* regular helper call sets R0 */
			bt_clear_reg(bt, BPF_REG_0);
			if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) {
				/* if backtracing was looking for registers R1-R5
				 * they should have been found already.
				 */
				verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
				WARN_ONCE(1, "verifier backtracking bug");
				return -EFAULT;
			}
		} else if (opcode == BPF_EXIT) {
			bool r0_precise;

			/* Backtracking to a nested function call, 'idx' is a part of
			 * the inner frame 'subseq_idx' is a part of the outer frame.
			 * In case of a regular function call, instructions giving
			 * precision to registers R1-R5 should have been found already.
			 * In case of a callback, it is ok to have R1-R5 marked for
			 * backtracking, as these registers are set by the function
			 * invoking callback.
			 */
			if (subseq_idx >= 0 && calls_callback(env, subseq_idx))
				for (i = BPF_REG_1; i <= BPF_REG_5; i++)
					bt_clear_reg(bt, i);
			if (bt_reg_mask(bt) & BPF_REGMASK_ARGS) {
				verbose(env, "BUG regs %x\n", bt_reg_mask(bt));
				WARN_ONCE(1, "verifier backtracking bug");
				return -EFAULT;
			}

			/* BPF_EXIT in subprog or callback always returns
			 * right after the call instruction, so by checking
			 * whether the instruction at subseq_idx-1 is subprog
			 * call or not we can distinguish actual exit from
			 * *subprog* from exit from *callback*. In the former
			 * case, we need to propagate r0 precision, if
			 * necessary. In the former we never do that.
			 */
			r0_precise = subseq_idx - 1 >= 0 &&
				     bpf_pseudo_call(&env->prog->insnsi[subseq_idx - 1]) &&
				     bt_is_reg_set(bt, BPF_REG_0);

			bt_clear_reg(bt, BPF_REG_0);
			if (bt_subprog_enter(bt))
				return -EFAULT;

			if (r0_precise)
				bt_set_reg(bt, BPF_REG_0);
			/* r6-r9 and stack slots will stay set in caller frame
			 * bitmasks until we return back from callee(s)
			 */
			return 0;
		} else if (BPF_SRC(insn->code) == BPF_X) {
			if (!bt_is_reg_set(bt, dreg) && !bt_is_reg_set(bt, sreg))
				return 0;
			/* dreg <cond> sreg
			 * Both dreg and sreg need precision before
			 * this insn. If only sreg was marked precise
			 * before it would be equally necessary to
			 * propagate it to dreg.
			 */
			bt_set_reg(bt, dreg);
			bt_set_reg(bt, sreg);
		} else if (BPF_SRC(insn->code) == BPF_K) {
			 /* dreg <cond> K
			  * Only dreg still needs precision before
			  * this insn, so for the K-based conditional
			  * there is nothing new to be marked.
			  */
		}
	} else if (class == BPF_LD) {
		if (!bt_is_reg_set(bt, dreg))
			return 0;
		bt_clear_reg(bt, dreg);
		/* It's ld_imm64 or ld_abs or ld_ind.
		 * For ld_imm64 no further tracking of precision
		 * into parent is necessary
		 */
		if (mode == BPF_IND || mode == BPF_ABS)
			/* to be analyzed */
			return -ENOTSUPP;
	}
	/* Propagate precision marks to linked registers, to account for
	 * registers marked as precise in this function.
	 */
	bt_sync_linked_regs(bt, hist);
	return 0;
}

/* the scalar precision tracking algorithm:
 * . at the start all registers have precise=false.
 * . scalar ranges are tracked as normal through alu and jmp insns.
 * . once precise value of the scalar register is used in:
 *   .  ptr + scalar alu
 *   . if (scalar cond K|scalar)
 *   .  helper_call(.., scalar, ...) where ARG_CONST is expected
 *   backtrack through the verifier states and mark all registers and
 *   stack slots with spilled constants that these scalar regisers
 *   should be precise.
 * . during state pruning two registers (or spilled stack slots)
 *   are equivalent if both are not precise.
 *
 * Note the verifier cannot simply walk register parentage chain,
 * since many different registers and stack slots could have been
 * used to compute single precise scalar.
 *
 * The approach of starting with precise=true for all registers and then
 * backtrack to mark a register as not precise when the verifier detects
 * that program doesn't care about specific value (e.g., when helper
 * takes register as ARG_ANYTHING parameter) is not safe.
 *
 * It's ok to walk single parentage chain of the verifier states.
 * It's possible that this backtracking will go all the way till 1st insn.
 * All other branches will be explored for needing precision later.
 *
 * The backtracking needs to deal with cases like:
 *   R8=map_value(id=0,off=0,ks=4,vs=1952,imm=0) R9_w=map_value(id=0,off=40,ks=4,vs=1952,imm=0)
 * r9 -= r8
 * r5 = r9
 * if r5 > 0x79f goto pc+7
 *    R5_w=inv(id=0,umax_value=1951,var_off=(0x0; 0x7ff))
 * r5 += 1
 * ...
 * call bpf_perf_event_output#25
 *   where .arg5_type = ARG_CONST_SIZE_OR_ZERO
 *
 * and this case:
 * r6 = 1
 * call foo // uses callee's r6 inside to compute r0
 * r0 += r6
 * if r0 == 0 goto
 *
 * to track above reg_mask/stack_mask needs to be independent for each frame.
 *
 * Also if parent's curframe > frame where backtracking started,
 * the verifier need to mark registers in both frames, otherwise callees
 * may incorrectly prune callers. This is similar to
 * commit 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences")
 *
 * For now backtracking falls back into conservative marking.
 */
static void mark_all_scalars_precise(struct bpf_verifier_env *env,
				     struct bpf_verifier_state *st)
{
	struct bpf_func_state *func;
	struct bpf_reg_state *reg;
	int i, j;

	if (env->log.level & BPF_LOG_LEVEL2) {
		verbose(env, "mark_precise: frame%d: falling back to forcing all scalars precise\n",
			st->curframe);
	}

	/* big hammer: mark all scalars precise in this path.
	 * pop_stack may still get !precise scalars.
	 * We also skip current state and go straight to first parent state,
	 * because precision markings in current non-checkpointed state are
	 * not needed. See why in the comment in __mark_chain_precision below.
	 */
	for (st = st->parent; st; st = st->parent) {
		for (i = 0; i <= st->curframe; i++) {
			func = st->frame[i];
			for (j = 0; j < BPF_REG_FP; j++) {
				reg = &func->regs[j];
				if (reg->type != SCALAR_VALUE || reg->precise)
					continue;
				reg->precise = true;
				if (env->log.level & BPF_LOG_LEVEL2) {
					verbose(env, "force_precise: frame%d: forcing r%d to be precise\n",
						i, j);
				}
			}
			for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
				if (!is_spilled_reg(&func->stack[j]))
					continue;
				reg = &func->stack[j].spilled_ptr;
				if (reg->type != SCALAR_VALUE || reg->precise)
					continue;
				reg->precise = true;
				if (env->log.level & BPF_LOG_LEVEL2) {
					verbose(env, "force_precise: frame%d: forcing fp%d to be precise\n",
						i, -(j + 1) * 8);
				}
			}
		}
	}
}

static void mark_all_scalars_imprecise(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
{
	struct bpf_func_state *func;
	struct bpf_reg_state *reg;
	int i, j;

	for (i = 0; i <= st->curframe; i++) {
		func = st->frame[i];
		for (j = 0; j < BPF_REG_FP; j++) {
			reg = &func->regs[j];
			if (reg->type != SCALAR_VALUE)
				continue;
			reg->precise = false;
		}
		for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
			if (!is_spilled_reg(&func->stack[j]))
				continue;
			reg = &func->stack[j].spilled_ptr;
			if (reg->type != SCALAR_VALUE)
				continue;
			reg->precise = false;
		}
	}
}

/*
 * __mark_chain_precision() backtracks BPF program instruction sequence and
 * chain of verifier states making sure that register *regno* (if regno >= 0)
 * and/or stack slot *spi* (if spi >= 0) are marked as precisely tracked
 * SCALARS, as well as any other registers and slots that contribute to
 * a tracked state of given registers/stack slots, depending on specific BPF
 * assembly instructions (see backtrack_insns() for exact instruction handling
 * logic). This backtracking relies on recorded jmp_history and is able to
 * traverse entire chain of parent states. This process ends only when all the
 * necessary registers/slots and their transitive dependencies are marked as
 * precise.
 *
 * One important and subtle aspect is that precise marks *do not matter* in
 * the currently verified state (current state). It is important to understand
 * why this is the case.
 *
 * First, note that current state is the state that is not yet "checkpointed",
 * i.e., it is not yet put into env->explored_states, and it has no children
 * states as well. It's ephemeral, and can end up either a) being discarded if
 * compatible explored state is found at some point or BPF_EXIT instruction is
 * reached or b) checkpointed and put into env->explored_states, branching out
 * into one or more children states.
 *
 * In the former case, precise markings in current state are completely
 * ignored by state comparison code (see regsafe() for details). Only
 * checkpointed ("old") state precise markings are important, and if old
 * state's register/slot is precise, regsafe() assumes current state's
 * register/slot as precise and checks value ranges exactly and precisely. If
 * states turn out to be compatible, current state's necessary precise
 * markings and any required parent states' precise markings are enforced
 * after the fact with propagate_precision() logic, after the fact. But it's
 * important to realize that in this case, even after marking current state
 * registers/slots as precise, we immediately discard current state. So what
 * actually matters is any of the precise markings propagated into current
 * state's parent states, which are always checkpointed (due to b) case above).
 * As such, for scenario a) it doesn't matter if current state has precise
 * markings set or not.
 *
 * Now, for the scenario b), checkpointing and forking into child(ren)
 * state(s). Note that before current state gets to checkpointing step, any
 * processed instruction always assumes precise SCALAR register/slot
 * knowledge: if precise value or range is useful to prune jump branch, BPF
 * verifier takes this opportunity enthusiastically. Similarly, when
 * register's value is used to calculate offset or memory address, exact
 * knowledge of SCALAR range is assumed, checked, and enforced. So, similar to
 * what we mentioned above about state comparison ignoring precise markings
 * during state comparison, BPF verifier ignores and also assumes precise
 * markings *at will* during instruction verification process. But as verifier
 * assumes precision, it also propagates any precision dependencies across
 * parent states, which are not yet finalized, so can be further restricted
 * based on new knowledge gained from restrictions enforced by their children
 * states. This is so that once those parent states are finalized, i.e., when
 * they have no more active children state, state comparison logic in
 * is_state_visited() would enforce strict and precise SCALAR ranges, if
 * required for correctness.
 *
 * To build a bit more intuition, note also that once a state is checkpointed,
 * the path we took to get to that state is not important. This is crucial
 * property for state pruning. When state is checkpointed and finalized at
 * some instruction index, it can be correctly and safely used to "short
 * circuit" any *compatible* state that reaches exactly the same instruction
 * index. I.e., if we jumped to that instruction from a completely different
 * code path than original finalized state was derived from, it doesn't
 * matter, current state can be discarded because from that instruction
 * forward having a compatible state will ensure we will safely reach the
 * exit. States describe preconditions for further exploration, but completely
 * forget the history of how we got here.
 *
 * This also means that even if we needed precise SCALAR range to get to
 * finalized state, but from that point forward *that same* SCALAR register is
 * never used in a precise context (i.e., it's precise value is not needed for
 * correctness), it's correct and safe to mark such register as "imprecise"
 * (i.e., precise marking set to false). This is what we rely on when we do
 * not set precise marking in current state. If no child state requires
 * precision for any given SCALAR register, it's safe to dictate that it can
 * be imprecise. If any child state does require this register to be precise,
 * we'll mark it precise later retroactively during precise markings
 * propagation from child state to parent states.
 *
 * Skipping precise marking setting in current state is a mild version of
 * relying on the above observation. But we can utilize this property even
 * more aggressively by proactively forgetting any precise marking in the
 * current state (which we inherited from the parent state), right before we
 * checkpoint it and branch off into new child state. This is done by
 * mark_all_scalars_imprecise() to hopefully get more permissive and generic
 * finalized states which help in short circuiting more future states.
 */
static int __mark_chain_precision(struct bpf_verifier_env *env, int regno)
{
	struct backtrack_state *bt = &env->bt;
	struct bpf_verifier_state *st = env->cur_state;
	int first_idx = st->first_insn_idx;
	int last_idx = env->insn_idx;
	int subseq_idx = -1;
	struct bpf_func_state *func;
	struct bpf_reg_state *reg;
	bool skip_first = true;
	int i, fr, err;

	if (!env->bpf_capable)
		return 0;

	/* set frame number from which we are starting to backtrack */
	bt_init(bt, env->cur_state->curframe);

	/* Do sanity checks against current state of register and/or stack
	 * slot, but don't set precise flag in current state, as precision
	 * tracking in the current state is unnecessary.
	 */
	func = st->frame[bt->frame];
	if (regno >= 0) {
		reg = &func->regs[regno];
		if (reg->type != SCALAR_VALUE) {
			WARN_ONCE(1, "backtracing misuse");
			return -EFAULT;
		}
		bt_set_reg(bt, regno);
	}

	if (bt_empty(bt))
		return 0;

	for (;;) {
		DECLARE_BITMAP(mask, 64);
		u32 history = st->jmp_history_cnt;
		struct bpf_jmp_history_entry *hist;

		if (env->log.level & BPF_LOG_LEVEL2) {
			verbose(env, "mark_precise: frame%d: last_idx %d first_idx %d subseq_idx %d \n",
				bt->frame, last_idx, first_idx, subseq_idx);
		}

		if (last_idx < 0) {
			/* we are at the entry into subprog, which
			 * is expected for global funcs, but only if
			 * requested precise registers are R1-R5
			 * (which are global func's input arguments)
			 */
			if (st->curframe == 0 &&
			    st->frame[0]->subprogno > 0 &&
			    st->frame[0]->callsite == BPF_MAIN_FUNC &&
			    bt_stack_mask(bt) == 0 &&
			    (bt_reg_mask(bt) & ~BPF_REGMASK_ARGS) == 0) {
				bitmap_from_u64(mask, bt_reg_mask(bt));
				for_each_set_bit(i, mask, 32) {
					reg = &st->frame[0]->regs[i];
					bt_clear_reg(bt, i);
					if (reg->type == SCALAR_VALUE)
						reg->precise = true;
				}
				return 0;
			}

			verbose(env, "BUG backtracking func entry subprog %d reg_mask %x stack_mask %llx\n",
				st->frame[0]->subprogno, bt_reg_mask(bt), bt_stack_mask(bt));
			WARN_ONCE(1, "verifier backtracking bug");
			return -EFAULT;
		}

		for (i = last_idx;;) {
			if (skip_first) {
				err = 0;
				skip_first = false;
			} else {
				hist = get_jmp_hist_entry(st, history, i);
				err = backtrack_insn(env, i, subseq_idx, hist, bt);
			}
			if (err == -ENOTSUPP) {
				mark_all_scalars_precise(env, env->cur_state);
				bt_reset(bt);
				return 0;
			} else if (err) {
				return err;
			}
			if (bt_empty(bt))
				/* Found assignment(s) into tracked register in this state.
				 * Since this state is already marked, just return.
				 * Nothing to be tracked further in the parent state.
				 */
				return 0;
			subseq_idx = i;
			i = get_prev_insn_idx(st, i, &history);
			if (i == -ENOENT)
				break;
			if (i >= env->prog->len) {
				/* This can happen if backtracking reached insn 0
				 * and there are still reg_mask or stack_mask
				 * to backtrack.
				 * It means the backtracking missed the spot where
				 * particular register was initialized with a constant.
				 */
				verbose(env, "BUG backtracking idx %d\n", i);
				WARN_ONCE(1, "verifier backtracking bug");
				return -EFAULT;
			}
		}
		st = st->parent;
		if (!st)
			break;

		for (fr = bt->frame; fr >= 0; fr--) {
			func = st->frame[fr];
			bitmap_from_u64(mask, bt_frame_reg_mask(bt, fr));
			for_each_set_bit(i, mask, 32) {
				reg = &func->regs[i];
				if (reg->type != SCALAR_VALUE) {
					bt_clear_frame_reg(bt, fr, i);
					continue;
				}
				if (reg->precise)
					bt_clear_frame_reg(bt, fr, i);
				else
					reg->precise = true;
			}

			bitmap_from_u64(mask, bt_frame_stack_mask(bt, fr));
			for_each_set_bit(i, mask, 64) {
				if (i >= func->allocated_stack / BPF_REG_SIZE) {
					verbose(env, "BUG backtracking (stack slot %d, total slots %d)\n",
						i, func->allocated_stack / BPF_REG_SIZE);
					WARN_ONCE(1, "verifier backtracking bug (stack slot out of bounds)");
					return -EFAULT;
				}

				if (!is_spilled_scalar_reg(&func->stack[i])) {
					bt_clear_frame_slot(bt, fr, i);
					continue;
				}
				reg = &func->stack[i].spilled_ptr;
				if (reg->precise)
					bt_clear_frame_slot(bt, fr, i);
				else
					reg->precise = true;
			}
			if (env->log.level & BPF_LOG_LEVEL2) {
				fmt_reg_mask(env->tmp_str_buf, TMP_STR_BUF_LEN,
					     bt_frame_reg_mask(bt, fr));
				verbose(env, "mark_precise: frame%d: parent state regs=%s ",
					fr, env->tmp_str_buf);
				fmt_stack_mask(env->tmp_str_buf, TMP_STR_BUF_LEN,
					       bt_frame_stack_mask(bt, fr));
				verbose(env, "stack=%s: ", env->tmp_str_buf);
				print_verifier_state(env, func, true);
			}
		}

		if (bt_empty(bt))
			return 0;

		subseq_idx = first_idx;
		last_idx = st->last_insn_idx;
		first_idx = st->first_insn_idx;
	}

	/* if we still have requested precise regs or slots, we missed
	 * something (e.g., stack access through non-r10 register), so
	 * fallback to marking all precise
	 */
	if (!bt_empty(bt)) {
		mark_all_scalars_precise(env, env->cur_state);
		bt_reset(bt);
	}

	return 0;
}

int mark_chain_precision(struct bpf_verifier_env *env, int regno)
{
	return __mark_chain_precision(env, regno);
}

/* mark_chain_precision_batch() assumes that env->bt is set in the caller to
 * desired reg and stack masks across all relevant frames
 */
static int mark_chain_precision_batch(struct bpf_verifier_env *env)
{
	return __mark_chain_precision(env, -1);
}

static bool is_spillable_regtype(enum bpf_reg_type type)
{
	switch (base_type(type)) {
	case PTR_TO_MAP_VALUE:
	case PTR_TO_STACK:
	case PTR_TO_CTX:
	case PTR_TO_PACKET:
	case PTR_TO_PACKET_META:
	case PTR_TO_PACKET_END:
	case PTR_TO_FLOW_KEYS:
	case CONST_PTR_TO_MAP:
	case PTR_TO_SOCKET:
	case PTR_TO_SOCK_COMMON:
	case PTR_TO_TCP_SOCK:
	case PTR_TO_XDP_SOCK:
	case PTR_TO_BTF_ID:
	case PTR_TO_BUF:
	case PTR_TO_MEM:
	case PTR_TO_FUNC:
	case PTR_TO_MAP_KEY:
	case PTR_TO_ARENA:
		return true;
	default:
		return false;
	}
}

/* Does this register contain a constant zero? */
static bool register_is_null(struct bpf_reg_state *reg)
{
	return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
}

/* check if register is a constant scalar value */
static bool is_reg_const(struct bpf_reg_state *reg, bool subreg32)
{
	return reg->type == SCALAR_VALUE &&
	       tnum_is_const(subreg32 ? tnum_subreg(reg->var_off) : reg->var_off);
}

/* assuming is_reg_const() is true, return constant value of a register */
static u64 reg_const_value(struct bpf_reg_state *reg, bool subreg32)
{
	return subreg32 ? tnum_subreg(reg->var_off).value : reg->var_off.value;
}

static bool __is_pointer_value(bool allow_ptr_leaks,
			       const struct bpf_reg_state *reg)
{
	if (allow_ptr_leaks)
		return false;

	return reg->type != SCALAR_VALUE;
}

static void assign_scalar_id_before_mov(struct bpf_verifier_env *env,
					struct bpf_reg_state *src_reg)
{
	if (src_reg->type != SCALAR_VALUE)
		return;

	if (src_reg->id & BPF_ADD_CONST) {
		/*
		 * The verifier is processing rX = rY insn and
		 * rY->id has special linked register already.
		 * Cleared it, since multiple rX += const are not supported.
		 */
		src_reg->id = 0;
		src_reg->off = 0;
	}

	if (!src_reg->id && !tnum_is_const(src_reg->var_off))
		/* Ensure that src_reg has a valid ID that will be copied to
		 * dst_reg and then will be used by sync_linked_regs() to
		 * propagate min/max range.
		 */
		src_reg->id = ++env->id_gen;
}

/* Copy src state preserving dst->parent and dst->live fields */
static void copy_register_state(struct bpf_reg_state *dst, const struct bpf_reg_state *src)
{
	struct bpf_reg_state *parent = dst->parent;
	enum bpf_reg_liveness live = dst->live;

	*dst = *src;
	dst->parent = parent;
	dst->live = live;
}

static void save_register_state(struct bpf_verifier_env *env,
				struct bpf_func_state *state,
				int spi, struct bpf_reg_state *reg,
				int size)
{
	int i;

	copy_register_state(&state->stack[spi].spilled_ptr, reg);
	if (size == BPF_REG_SIZE)
		state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;

	for (i = BPF_REG_SIZE; i > BPF_REG_SIZE - size; i--)
		state->stack[spi].slot_type[i - 1] = STACK_SPILL;

	/* size < 8 bytes spill */
	for (; i; i--)
		mark_stack_slot_misc(env, &state->stack[spi].slot_type[i - 1]);
}

static bool is_bpf_st_mem(struct bpf_insn *insn)
{
	return BPF_CLASS(insn->code) == BPF_ST && BPF_MODE(insn->code) == BPF_MEM;
}

static int get_reg_width(struct bpf_reg_state *reg)
{
	return fls64(reg->umax_value);
}

/* See comment for mark_fastcall_pattern_for_call() */
static void check_fastcall_stack_contract(struct bpf_verifier_env *env,
					  struct bpf_func_state *state, int insn_idx, int off)
{
	struct bpf_subprog_info *subprog = &env->subprog_info[state->subprogno];
	struct bpf_insn_aux_data *aux = env->insn_aux_data;
	int i;

	if (subprog->fastcall_stack_off <= off || aux[insn_idx].fastcall_pattern)
		return;
	/* access to the region [max_stack_depth .. fastcall_stack_off)
	 * from something that is not a part of the fastcall pattern,
	 * disable fastcall rewrites for current subprogram by setting
	 * fastcall_stack_off to a value smaller than any possible offset.
	 */
	subprog->fastcall_stack_off = S16_MIN;
	/* reset fastcall aux flags within subprogram,
	 * happens at most once per subprogram
	 */
	for (i = subprog->start; i < (subprog + 1)->start; ++i) {
		aux[i].fastcall_spills_num = 0;
		aux[i].fastcall_pattern = 0;
	}
}

/* check_stack_{read,write}_fixed_off functions track spill/fill of registers,
 * stack boundary and alignment are checked in check_mem_access()
 */
static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
				       /* stack frame we're writing to */
				       struct bpf_func_state *state,
				       int off, int size, int value_regno,
				       int insn_idx)
{
	struct bpf_func_state *cur; /* state of the current function */
	int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
	struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
	struct bpf_reg_state *reg = NULL;
	int insn_flags = insn_stack_access_flags(state->frameno, spi);

	/* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
	 * so it's aligned access and [off, off + size) are within stack limits
	 */
	if (!env->allow_ptr_leaks &&
	    is_spilled_reg(&state->stack[spi]) &&
	    size != BPF_REG_SIZE) {
		verbose(env, "attempt to corrupt spilled pointer on stack\n");
		return -EACCES;
	}

	cur = env->cur_state->frame[env->cur_state->curframe];
	if (value_regno >= 0)
		reg = &cur->regs[value_regno];
	if (!env->bypass_spec_v4) {
		bool sanitize = reg && is_spillable_regtype(reg->type);

		for (i = 0; i < size; i++) {
			u8 type = state->stack[spi].slot_type[i];

			if (type != STACK_MISC && type != STACK_ZERO) {
				sanitize = true;
				break;
			}
		}

		if (sanitize)
			env->insn_aux_data[insn_idx].sanitize_stack_spill = true;
	}

	err = destroy_if_dynptr_stack_slot(env, state, spi);
	if (err)
		return err;

	check_fastcall_stack_contract(env, state, insn_idx, off);
	mark_stack_slot_scratched(env, spi);
	if (reg && !(off % BPF_REG_SIZE) && reg->type == SCALAR_VALUE && env->bpf_capable) {
		bool reg_value_fits;

		reg_value_fits = get_reg_width(reg) <= BITS_PER_BYTE * size;
		/* Make sure that reg had an ID to build a relation on spill. */
		if (reg_value_fits)
			assign_scalar_id_before_mov(env, reg);
		save_register_state(env, state, spi, reg, size);
		/* Break the relation on a narrowing spill. */
		if (!reg_value_fits)
			state->stack[spi].spilled_ptr.id = 0;
	} else if (!reg && !(off % BPF_REG_SIZE) && is_bpf_st_mem(insn) &&
		   env->bpf_capable) {
		struct bpf_reg_state *tmp_reg = &env->fake_reg[0];

		memset(tmp_reg, 0, sizeof(*tmp_reg));
		__mark_reg_known(tmp_reg, insn->imm);
		tmp_reg->type = SCALAR_VALUE;
		save_register_state(env, state, spi, tmp_reg, size);
	} else if (reg && is_spillable_regtype(reg->type)) {
		/* register containing pointer is being spilled into stack */
		if (size != BPF_REG_SIZE) {
			verbose_linfo(env, insn_idx, "; ");
			verbose(env, "invalid size of register spill\n");
			return -EACCES;
		}
		if (state != cur && reg->type == PTR_TO_STACK) {
			verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
			return -EINVAL;
		}
		save_register_state(env, state, spi, reg, size);
	} else {
		u8 type = STACK_MISC;

		/* regular write of data into stack destroys any spilled ptr */
		state->stack[spi].spilled_ptr.type = NOT_INIT;
		/* Mark slots as STACK_MISC if they belonged to spilled ptr/dynptr/iter. */
		if (is_stack_slot_special(&state->stack[spi]))
			for (i = 0; i < BPF_REG_SIZE; i++)
				scrub_spilled_slot(&state->stack[spi].slot_type[i]);

		/* only mark the slot as written if all 8 bytes were written
		 * otherwise read propagation may incorrectly stop too soon
		 * when stack slots are partially written.
		 * This heuristic means that read propagation will be
		 * conservative, since it will add reg_live_read marks
		 * to stack slots all the way to first state when programs
		 * writes+reads less than 8 bytes
		 */
		if (size == BPF_REG_SIZE)
			state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;

		/* when we zero initialize stack slots mark them as such */
		if ((reg && register_is_null(reg)) ||
		    (!reg && is_bpf_st_mem(insn) && insn->imm == 0)) {
			/* STACK_ZERO case happened because register spill
			 * wasn't properly aligned at the stack slot boundary,
			 * so it's not a register spill anymore; force
			 * originating register to be precise to make
			 * STACK_ZERO correct for subsequent states
			 */
			err = mark_chain_precision(env, value_regno);
			if (err)
				return err;
			type = STACK_ZERO;
		}

		/* Mark slots affected by this stack write. */
		for (i = 0; i < size; i++)
			state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] = type;
		insn_flags = 0; /* not a register spill */
	}

	if (insn_flags)
		return push_jmp_history(env, env->cur_state, insn_flags, 0);
	return 0;
}

/* Write the stack: 'stack[ptr_regno + off] = value_regno'. 'ptr_regno' is
 * known to contain a variable offset.
 * This function checks whether the write is permitted and conservatively
 * tracks the effects of the write, considering that each stack slot in the
 * dynamic range is potentially written to.
 *
 * 'off' includes 'regno->off'.
 * 'value_regno' can be -1, meaning that an unknown value is being written to
 * the stack.
 *
 * Spilled pointers in range are not marked as written because we don't know
 * what's going to be actually written. This means that read propagation for
 * future reads cannot be terminated by this write.
 *
 * For privileged programs, uninitialized stack slots are considered
 * initialized by this write (even though we don't know exactly what offsets
 * are going to be written to). The idea is that we don't want the verifier to
 * reject future reads that access slots written to through variable offsets.
 */
static int check_stack_write_var_off(struct bpf_verifier_env *env,
				     /* func where register points to */
				     struct bpf_func_state *state,
				     int ptr_regno, int off, int size,
				     int value_regno, int insn_idx)
{
	struct bpf_func_state *cur; /* state of the current function */
	int min_off, max_off;
	int i, err;
	struct bpf_reg_state *ptr_reg = NULL, *value_reg = NULL;
	struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
	bool writing_zero = false;
	/* set if the fact that we're writing a zero is used to let any
	 * stack slots remain STACK_ZERO
	 */
	bool zero_used = false;

	cur = env->cur_state->frame[env->cur_state->curframe];
	ptr_reg = &cur->regs[ptr_regno];
	min_off = ptr_reg->smin_value + off;
	max_off = ptr_reg->smax_value + off + size;
	if (value_regno >= 0)
		value_reg = &cur->regs[value_regno];
	if ((value_reg && register_is_null(value_reg)) ||
	    (!value_reg && is_bpf_st_mem(insn) && insn->imm == 0))
		writing_zero = true;

	for (i = min_off; i < max_off; i++) {
		int spi;

		spi = __get_spi(i);
		err = destroy_if_dynptr_stack_slot(env, state, spi);
		if (err)
			return err;
	}

	check_fastcall_stack_contract(env, state, insn_idx, min_off);
	/* Variable offset writes destroy any spilled pointers in range. */
	for (i = min_off; i < max_off; i++) {
		u8 new_type, *stype;
		int slot, spi;

		slot = -i - 1;
		spi = slot / BPF_REG_SIZE;
		stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
		mark_stack_slot_scratched(env, spi);

		if (!env->allow_ptr_leaks && *stype != STACK_MISC && *stype != STACK_ZERO) {
			/* Reject the write if range we may write to has not
			 * been initialized beforehand. If we didn't reject
			 * here, the ptr status would be erased below (even
			 * though not all slots are actually overwritten),
			 * possibly opening the door to leaks.
			 *
			 * We do however catch STACK_INVALID case below, and
			 * only allow reading possibly uninitialized memory
			 * later for CAP_PERFMON, as the write may not happen to
			 * that slot.
			 */
			verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d",
				insn_idx, i);
			return -EINVAL;
		}

		/* If writing_zero and the spi slot contains a spill of value 0,
		 * maintain the spill type.
		 */
		if (writing_zero && *stype == STACK_SPILL &&
		    is_spilled_scalar_reg(&state->stack[spi])) {
			struct bpf_reg_state *spill_reg = &state->stack[spi].spilled_ptr;

			if (tnum_is_const(spill_reg->var_off) && spill_reg->var_off.value == 0) {
				zero_used = true;
				continue;
			}
		}

		/* Erase all other spilled pointers. */
		state->stack[spi].spilled_ptr.type = NOT_INIT;

		/* Update the slot type. */
		new_type = STACK_MISC;
		if (writing_zero && *stype == STACK_ZERO) {
			new_type = STACK_ZERO;
			zero_used = true;
		}
		/* If the slot is STACK_INVALID, we check whether it's OK to
		 * pretend that it will be initialized by this write. The slot
		 * might not actually be written to, and so if we mark it as
		 * initialized future reads might leak uninitialized memory.
		 * For privileged programs, we will accept such reads to slots
		 * that may or may not be written because, if we're reject
		 * them, the error would be too confusing.
		 */
		if (*stype == STACK_INVALID && !env->allow_uninit_stack) {
			verbose(env, "uninit stack in range of var-offset write prohibited for !root; insn %d, off: %d",
					insn_idx, i);
			return -EINVAL;
		}
		*stype = new_type;
	}
	if (zero_used) {
		/* backtracking doesn't work for STACK_ZERO yet. */
		err = mark_chain_precision(env, value_regno);
		if (err)
			return err;
	}
	return 0;
}

/* When register 'dst_regno' is assigned some values from stack[min_off,
 * max_off), we set the register's type according to the types of the
 * respective stack slots. If all the stack values are known to be zeros, then
 * so is the destination reg. Otherwise, the register is considered to be
 * SCALAR. This function does not deal with register filling; the caller must
 * ensure that all spilled registers in the stack range have been marked as
 * read.
 */
static void mark_reg_stack_read(struct bpf_verifier_env *env,
				/* func where src register points to */
				struct bpf_func_state *ptr_state,
				int min_off, int max_off, int dst_regno)
{
	struct bpf_verifier_state *vstate = env->cur_state;
	struct bpf_func_state *state = vstate->frame[vstate->curframe];
	int i, slot, spi;
	u8 *stype;
	int zeros = 0;

	for (i = min_off; i < max_off; i++) {
		slot = -i - 1;
		spi = slot / BPF_REG_SIZE;
		mark_stack_slot_scratched(env, spi);
		stype = ptr_state->stack[spi].slot_type;
		if (stype[slot % BPF_REG_SIZE] != STACK_ZERO)
			break;
		zeros++;
	}
	if (zeros == max_off - min_off) {
		/* Any access_size read into register is zero extended,
		 * so the whole register == const_zero.
		 */
		__mark_reg_const_zero(env, &state->regs[dst_regno]);
	} else {
		/* have read misc data from the stack */
		mark_reg_unknown(env, state->regs, dst_regno);
	}
	state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
}

/* Read the stack at 'off' and put the results into the register indicated by
 * 'dst_regno'. It handles reg filling if the addressed stack slot is a
 * spilled reg.
 *
 * 'dst_regno' can be -1, meaning that the read value is not going to a
 * register.
 *
 * The access is assumed to be within the current stack bounds.
 */
static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
				      /* func where src register points to */
				      struct bpf_func_state *reg_state,
				      int off, int size, int dst_regno)
{
	struct bpf_verifier_state *vstate = env->cur_state;
	struct bpf_func_state *state = vstate->frame[vstate->curframe];
	int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
	struct bpf_reg_state *reg;
	u8 *stype, type;
	int insn_flags = insn_stack_access_flags(reg_state->frameno, spi);

	stype = reg_state->stack[spi].slot_type;
	reg = &reg_state->stack[spi].spilled_ptr;

	mark_stack_slot_scratched(env, spi);
	check_fastcall_stack_contract(env, state, env->insn_idx, off);

	if (is_spilled_reg(&reg_state->stack[spi])) {
		u8 spill_size = 1;

		for (i = BPF_REG_SIZE - 1; i > 0 && stype[i - 1] == STACK_SPILL; i--)
			spill_size++;

		if (size != BPF_REG_SIZE || spill_size != BPF_REG_SIZE) {
			if (reg->type != SCALAR_VALUE) {
				verbose_linfo(env, env->insn_idx, "; ");
				verbose(env, "invalid size of register fill\n");
				return -EACCES;
			}

			mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
			if (dst_regno < 0)
				return 0;

			if (size <= spill_size &&
			    bpf_stack_narrow_access_ok(off, size, spill_size)) {
				/* The earlier check_reg_arg() has decided the
				 * subreg_def for this insn.  Save it first.
				 */
				s32 subreg_def = state->regs[dst_regno].subreg_def;

				copy_register_state(&state->regs[dst_regno], reg);
				state->regs[dst_regno].subreg_def = subreg_def;

				/* Break the relation on a narrowing fill.
				 * coerce_reg_to_size will adjust the boundaries.
				 */
				if (get_reg_width(reg) > size * BITS_PER_BYTE)
					state->regs[dst_regno].id = 0;
			} else {
				int spill_cnt = 0, zero_cnt = 0;

				for (i = 0; i < size; i++) {
					type = stype[(slot - i) % BPF_REG_SIZE];
					if (type == STACK_SPILL) {
						spill_cnt++;
						continue;
					}
					if (type == STACK_MISC)
						continue;
					if (type == STACK_ZERO) {
						zero_cnt++;
						continue;
					}
					if (type == STACK_INVALID && env->allow_uninit_stack)
						continue;
					verbose(env, "invalid read from stack off %d+%d size %d\n",
						off, i, size);
					return -EACCES;
				}

				if (spill_cnt == size &&
				    tnum_is_const(reg->var_off) && reg->var_off.value == 0) {
					__mark_reg_const_zero(env, &state->regs[dst_regno]);
					/* this IS register fill, so keep insn_flags */
				} else if (zero_cnt == size) {
					/* similarly to mark_reg_stack_read(), preserve zeroes */
					__mark_reg_const_zero(env, &state->regs[dst_regno]);
					insn_flags = 0; /* not restoring original register state */
				} else {
					mark_reg_unknown(env, state->regs, dst_regno);
					insn_flags = 0; /* not restoring original register state */
				}
			}
			state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
		} else if (dst_regno >= 0) {
			/* restore register state from stack */
			copy_register_state(&state->regs[dst_regno], reg);
			/* mark reg as written since spilled pointer state likely
			 * has its liveness marks cleared by is_state_visited()
			 * which resets stack/reg liveness for state transitions
			 */
			state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
		} else if (__is_pointer_value(env->allow_ptr_leaks, reg)) {
			/* If dst_regno==-1, the caller is asking us whether
			 * it is acceptable to use this value as a SCALAR_VALUE
			 * (e.g. for XADD).
			 * We must not allow unprivileged callers to do that
			 * with spilled pointers.
			 */
			verbose(env, "leaking pointer from stack off %d\n",
				off);
			return -EACCES;
		}
		mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
	} else {
		for (i = 0; i < size; i++) {
			type = stype[(slot - i) % BPF_REG_SIZE];
			if (type == STACK_MISC)
				continue;
			if (type == STACK_ZERO)
				continue;
			if (type == STACK_INVALID && env->allow_uninit_stack)
				continue;
			verbose(env, "invalid read from stack off %d+%d size %d\n",
				off, i, size);
			return -EACCES;
		}
		mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
		if (dst_regno >= 0)
			mark_reg_stack_read(env, reg_state, off, off + size, dst_regno);
		insn_flags = 0; /* we are not restoring spilled register */
	}
	if (insn_flags)
		return push_jmp_history(env, env->cur_state, insn_flags, 0);
	return 0;
}

enum bpf_access_src {
	ACCESS_DIRECT = 1,  /* the access is performed by an instruction */
	ACCESS_HELPER = 2,  /* the access is performed by a helper */
};

static int check_stack_range_initialized(struct bpf_verifier_env *env,
					 int regno, int off, int access_size,
					 bool zero_size_allowed,
					 enum bpf_access_src type,
					 struct bpf_call_arg_meta *meta);

static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno)
{
	return cur_regs(env) + regno;
}

/* Read the stack at 'ptr_regno + off' and put the result into the register
 * 'dst_regno'.
 * 'off' includes the pointer register's fixed offset(i.e. 'ptr_regno.off'),
 * but not its variable offset.
 * 'size' is assumed to be <= reg size and the access is assumed to be aligned.
 *
 * As opposed to check_stack_read_fixed_off, this function doesn't deal with
 * filling registers (i.e. reads of spilled register cannot be detected when
 * the offset is not fixed). We conservatively mark 'dst_regno' as containing
 * SCALAR_VALUE. That's why we assert that the 'ptr_regno' has a variable
 * offset; for a fixed offset check_stack_read_fixed_off should be used
 * instead.
 */
static int check_stack_read_var_off(struct bpf_verifier_env *env,
				    int ptr_regno, int off, int size, int dst_regno)
{
	/* The state of the source register. */
	struct bpf_reg_state *reg = reg_state(env, ptr_regno);
	struct bpf_func_state *ptr_state = func(env, reg);
	int err;
	int min_off, max_off;

	/* Note that we pass a NULL meta, so raw access will not be permitted.
	 */
	err = check_stack_range_initialized(env, ptr_regno, off, size,
					    false, ACCESS_DIRECT, NULL);
	if (err)
		return err;

	min_off = reg->smin_value + off;
	max_off = reg->smax_value + off;
	mark_reg_stack_read(env, ptr_state, min_off, max_off + size, dst_regno);
	check_fastcall_stack_contract(env, ptr_state, env->insn_idx, min_off);
	return 0;
}

/* check_stack_read dispatches to check_stack_read_fixed_off or
 * check_stack_read_var_off.
 *
 * The caller must ensure that the offset falls within the allocated stack
 * bounds.
 *
 * 'dst_regno' is a register which will receive the value from the stack. It
 * can be -1, meaning that the read value is not going to a register.
 */
static int check_stack_read(struct bpf_verifier_env *env,
			    int ptr_regno, int off, int size,
			    int dst_regno)
{
	struct bpf_reg_state *reg = reg_state(env, ptr_regno);
	struct bpf_func_state *state = func(env, reg);
	int err;
	/* Some accesses are only permitted with a static offset. */
	bool var_off = !tnum_is_const(reg->var_off);

	/* The offset is required to be static when reads don't go to a
	 * register, in order to not leak pointers (see
	 * check_stack_read_fixed_off).
	 */
	if (dst_regno < 0 && var_off) {
		char tn_buf[48];

		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
		verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n",
			tn_buf, off, size);
		return -EACCES;
	}
	/* Variable offset is prohibited for unprivileged mode for simplicity
	 * since it requires corresponding support in Spectre masking for stack
	 * ALU. See also retrieve_ptr_limit(). The check in
	 * check_stack_access_for_ptr_arithmetic() called by
	 * adjust_ptr_min_max_vals() prevents users from creating stack pointers
	 * with variable offsets, therefore no check is required here. Further,
	 * just checking it here would be insufficient as speculative stack
	 * writes could still lead to unsafe speculative behaviour.
	 */
	if (!var_off) {
		off += reg->var_off.value;
		err = check_stack_read_fixed_off(env, state, off, size,
						 dst_regno);
	} else {
		/* Variable offset stack reads need more conservative handling
		 * than fixed offset ones. Note that dst_regno >= 0 on this
		 * branch.
		 */
		err = check_stack_read_var_off(env, ptr_regno, off, size,
					       dst_regno);
	}
	return err;
}


/* check_stack_write dispatches to check_stack_write_fixed_off or
 * check_stack_write_var_off.
 *
 * 'ptr_regno' is the register used as a pointer into the stack.
 * 'off' includes 'ptr_regno->off', but not its variable offset (if any).
 * 'value_regno' is the register whose value we're writing to the stack. It can
 * be -1, meaning that we're not writing from a register.
 *
 * The caller must ensure that the offset falls within the maximum stack size.
 */
static int check_stack_write(struct bpf_verifier_env *env,
			     int ptr_regno, int off, int size,
			     int value_regno, int insn_idx)
{
	struct bpf_reg_state *reg = reg_state(env, ptr_regno);
	struct bpf_func_state *state = func(env, reg);
	int err;

	if (tnum_is_const(reg->var_off)) {
		off += reg->var_off.value;
		err = check_stack_write_fixed_off(env, state, off, size,
						  value_regno, insn_idx);
	} else {
		/* Variable offset stack reads need more conservative handling
		 * than fixed offset ones.
		 */
		err = check_stack_write_var_off(env, state,
						ptr_regno, off, size,
						value_regno, insn_idx);
	}
	return err;
}

static int check_map_access_type(struct bpf_verifier_env *env, u32 regno,
				 int off, int size, enum bpf_access_type type)
{
	struct bpf_reg_state *regs = cur_regs(env);
	struct bpf_map *map = regs[regno].map_ptr;
	u32 cap = bpf_map_flags_to_cap(map);

	if (type == BPF_WRITE && !(cap & BPF_MAP_CAN_WRITE)) {
		verbose(env, "write into map forbidden, value_size=%d off=%d size=%d\n",
			map->value_size, off, size);
		return -EACCES;
	}

	if (type == BPF_READ && !(cap & BPF_MAP_CAN_READ)) {
		verbose(env, "read from map forbidden, value_size=%d off=%d size=%d\n",
			map->value_size, off, size);
		return -EACCES;
	}

	return 0;
}

/* check read/write into memory region (e.g., map value, ringbuf sample, etc) */
static int __check_mem_access(struct bpf_verifier_env *env, int regno,
			      int off, int size, u32 mem_size,
			      bool zero_size_allowed)
{
	bool size_ok = size > 0 || (size == 0 && zero_size_allowed);
	struct bpf_reg_state *reg;

	if (off >= 0 && size_ok && (u64)off + size <= mem_size)
		return 0;

	reg = &cur_regs(env)[regno];
	switch (reg->type) {
	case PTR_TO_MAP_KEY:
		verbose(env, "invalid access to map key, key_size=%d off=%d size=%d\n",
			mem_size, off, size);
		break;
	case PTR_TO_MAP_VALUE:
		verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n",
			mem_size, off, size);
		break;
	case PTR_TO_PACKET:
	case PTR_TO_PACKET_META:
	case PTR_TO_PACKET_END:
		verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
			off, size, regno, reg->id, off, mem_size);
		break;
	case PTR_TO_MEM:
	default:
		verbose(env, "invalid access to memory, mem_size=%u off=%d size=%d\n",
			mem_size, off, size);
	}

	return -EACCES;
}

/* check read/write into a memory region with possible variable offset */
static int check_mem_region_access(struct bpf_verifier_env *env, u32 regno,
				   int off, int size, u32 mem_size,
				   bool zero_size_allowed)
{
	struct bpf_verifier_state *vstate = env->cur_state;
	struct bpf_func_state *state = vstate->frame[vstate->curframe];
	struct bpf_reg_state *reg = &state->regs[regno];
	int err;

	/* We may have adjusted the register pointing to memory region, so we
	 * need to try adding each of min_value and max_value to off
	 * to make sure our theoretical access will be safe.
	 *
	 * The minimum value is only important with signed
	 * comparisons where we can't assume the floor of a
	 * value is 0.  If we are using signed variables for our
	 * index'es we need to make sure that whatever we use
	 * will have a set floor within our range.
	 */
	if (reg->smin_value < 0 &&
	    (reg->smin_value == S64_MIN ||
	     (off + reg->smin_value != (s64)(s32)(off + reg->smin_value)) ||
	      reg->smin_value + off < 0)) {
		verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
			regno);
		return -EACCES;
	}
	err = __check_mem_access(env, regno, reg->smin_value + off, size,
				 mem_size, zero_size_allowed);
	if (err) {
		verbose(env, "R%d min value is outside of the allowed memory range\n",
			regno);
		return err;
	}

	/* If we haven't set a max value then we need to bail since we can't be
	 * sure we won't do bad things.
	 * If reg->umax_value + off could overflow, treat that as unbounded too.
	 */
	if (reg->umax_value >= BPF_MAX_VAR_OFF) {
		verbose(env, "R%d unbounded memory access, make sure to bounds check any such access\n",
			regno);
		return -EACCES;
	}
	err = __check_mem_access(env, regno, reg->umax_value + off, size,
				 mem_size, zero_size_allowed);
	if (err) {
		verbose(env, "R%d max value is outside of the allowed memory range\n",
			regno);
		return err;
	}

	return 0;
}

static int __check_ptr_off_reg(struct bpf_verifier_env *env,
			       const struct bpf_reg_state *reg, int regno,
			       bool fixed_off_ok)
{
	/* Access to this pointer-typed register or passing it to a helper
	 * is only allowed in its original, unmodified form.
	 */

	if (reg->off < 0) {
		verbose(env, "negative offset %s ptr R%d off=%d disallowed\n",
			reg_type_str(env, reg->type), regno, reg->off);
		return -EACCES;
	}

	if (!fixed_off_ok && reg->off) {
		verbose(env, "dereference of modified %s ptr R%d off=%d disallowed\n",
			reg_type_str(env, reg->type), regno, reg->off);
		return -EACCES;
	}

	if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
		char tn_buf[48];

		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
		verbose(env, "variable %s access var_off=%s disallowed\n",
			reg_type_str(env, reg->type), tn_buf);
		return -EACCES;
	}

	return 0;
}

static int check_ptr_off_reg(struct bpf_verifier_env *env,
		             const struct bpf_reg_state *reg, int regno)
{
	return __check_ptr_off_reg(env, reg, regno, false);
}

static int map_kptr_match_type(struct bpf_verifier_env *env,
			       struct btf_field *kptr_field,
			       struct bpf_reg_state *reg, u32 regno)
{
	const char *targ_name = btf_type_name(kptr_field->kptr.btf, kptr_field->kptr.btf_id);
	int perm_flags;
	const char *reg_name = "";

	if (btf_is_kernel(reg->btf)) {
		perm_flags = PTR_MAYBE_NULL | PTR_TRUSTED | MEM_RCU;

		/* Only unreferenced case accepts untrusted pointers */
		if (kptr_field->type == BPF_KPTR_UNREF)
			perm_flags |= PTR_UNTRUSTED;
	} else {
		perm_flags = PTR_MAYBE_NULL | MEM_ALLOC;
		if (kptr_field->type == BPF_KPTR_PERCPU)
			perm_flags |= MEM_PERCPU;
	}

	if (base_type(reg->type) != PTR_TO_BTF_ID || (type_flag(reg->type) & ~perm_flags))
		goto bad_type;

	/* We need to verify reg->type and reg->btf, before accessing reg->btf */
	reg_name = btf_type_name(reg->btf, reg->btf_id);

	/* For ref_ptr case, release function check should ensure we get one
	 * referenced PTR_TO_BTF_ID, and that its fixed offset is 0. For the
	 * normal store of unreferenced kptr, we must ensure var_off is zero.
	 * Since ref_ptr cannot be accessed directly by BPF insns, checks for
	 * reg->off and reg->ref_obj_id are not needed here.
	 */
	if (__check_ptr_off_reg(env, reg, regno, true))
		return -EACCES;

	/* A full type match is needed, as BTF can be vmlinux, module or prog BTF, and
	 * we also need to take into account the reg->off.
	 *
	 * We want to support cases like:
	 *
	 * struct foo {
	 *         struct bar br;
	 *         struct baz bz;
	 * };
	 *
	 * struct foo *v;
	 * v = func();	      // PTR_TO_BTF_ID
	 * val->foo = v;      // reg->off is zero, btf and btf_id match type
	 * val->bar = &v->br; // reg->off is still zero, but we need to retry with
	 *                    // first member type of struct after comparison fails
	 * val->baz = &v->bz; // reg->off is non-zero, so struct needs to be walked
	 *                    // to match type
	 *
	 * In the kptr_ref case, check_func_arg_reg_off already ensures reg->off
	 * is zero. We must also ensure that btf_struct_ids_match does not walk
	 * the struct to match type against first member of struct, i.e. reject
	 * second case from above. Hence, when type is BPF_KPTR_REF, we set
	 * strict mode to true for type match.
	 */
	if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off,
				  kptr_field->kptr.btf, kptr_field->kptr.btf_id,
				  kptr_field->type != BPF_KPTR_UNREF))
		goto bad_type;
	return 0;
bad_type:
	verbose(env, "invalid kptr access, R%d type=%s%s ", regno,
		reg_type_str(env, reg->type), reg_name);
	verbose(env, "expected=%s%s", reg_type_str(env, PTR_TO_BTF_ID), targ_name);
	if (kptr_field->type == BPF_KPTR_UNREF)
		verbose(env, " or %s%s\n", reg_type_str(env, PTR_TO_BTF_ID | PTR_UNTRUSTED),
			targ_name);
	else
		verbose(env, "\n");
	return -EINVAL;
}

static bool in_sleepable(struct bpf_verifier_env *env)
{
	return env->prog->sleepable ||
	       (env->cur_state && env->cur_state->in_sleepable);
}

/* The non-sleepable programs and sleepable programs with explicit bpf_rcu_read_lock()
 * can dereference RCU protected pointers and result is PTR_TRUSTED.
 */
static bool in_rcu_cs(struct bpf_verifier_env *env)
{
	return env->cur_state->active_rcu_lock ||
	       env->cur_state->active_lock.ptr ||
	       !in_sleepable(env);
}

/* Once GCC supports btf_type_tag the following mechanism will be replaced with tag check */
BTF_SET_START(rcu_protected_types)
BTF_ID(struct, prog_test_ref_kfunc)
#ifdef CONFIG_CGROUPS
BTF_ID(struct, cgroup)
#endif
#ifdef CONFIG_BPF_JIT
BTF_ID(struct, bpf_cpumask)
#endif
BTF_ID(struct, task_struct)
BTF_ID(struct, bpf_crypto_ctx)
BTF_SET_END(rcu_protected_types)

static bool rcu_protected_object(const struct btf *btf, u32 btf_id)
{
	if (!btf_is_kernel(btf))
		return true;
	return btf_id_set_contains(&rcu_protected_types, btf_id);
}

static struct btf_record *kptr_pointee_btf_record(struct btf_field *kptr_field)
{
	struct btf_struct_meta *meta;

	if (btf_is_kernel(kptr_field->kptr.btf))
		return NULL;

	meta = btf_find_struct_meta(kptr_field->kptr.btf,
				    kptr_field->kptr.btf_id);

	return meta ? meta->record : NULL;
}

static bool rcu_safe_kptr(const struct btf_field *field)
{
	const struct btf_field_kptr *kptr = &field->kptr;

	return field->type == BPF_KPTR_PERCPU ||
	       (field->type == BPF_KPTR_REF && rcu_protected_object(kptr->btf, kptr->btf_id));
}

static u32 btf_ld_kptr_type(struct bpf_verifier_env *env, struct btf_field *kptr_field)
{
	struct btf_record *rec;
	u32 ret;

	ret = PTR_MAYBE_NULL;
	if (rcu_safe_kptr(kptr_field) && in_rcu_cs(env)) {
		ret |= MEM_RCU;
		if (kptr_field->type == BPF_KPTR_PERCPU)
			ret |= MEM_PERCPU;
		else if (!btf_is_kernel(kptr_field->kptr.btf))
			ret |= MEM_ALLOC;

		rec = kptr_pointee_btf_record(kptr_field);
		if (rec && btf_record_has_field(rec, BPF_GRAPH_NODE))
			ret |= NON_OWN_REF;
	} else {
		ret |= PTR_UNTRUSTED;
	}

	return ret;
}

static int check_map_kptr_access(struct bpf_verifier_env *env, u32 regno,
				 int value_regno, int insn_idx,
				 struct btf_field *kptr_field)
{
	struct bpf_insn *insn = &env->prog->insnsi[insn_idx];
	int class = BPF_CLASS(insn->code);
	struct bpf_reg_state *val_reg;

	/* Things we already checked for in check_map_access and caller:
	 *  - Reject cases where variable offset may touch kptr
	 *  - size of access (must be BPF_DW)
	 *  - tnum_is_const(reg->var_off)
	 *  - kptr_field->offset == off + reg->var_off.value
	 */
	/* Only BPF_[LDX,STX,ST] | BPF_MEM | BPF_DW is supported */
	if (BPF_MODE(insn->code) != BPF_MEM) {
		verbose(env, "kptr in map can only be accessed using BPF_MEM instruction mode\n");
		return -EACCES;
	}

	/* We only allow loading referenced kptr, since it will be marked as
	 * untrusted, similar to unreferenced kptr.
	 */
	if (class != BPF_LDX &&
	    (kptr_field->type == BPF_KPTR_REF || kptr_field->type == BPF_KPTR_PERCPU)) {
		verbose(env, "store to referenced kptr disallowed\n");
		return -EACCES;
	}

	if (class == BPF_LDX) {
		val_reg = reg_state(env, value_regno);
		/* We can simply mark the value_regno receiving the pointer
		 * value from map as PTR_TO_BTF_ID, with the correct type.
		 */
		mark_btf_ld_reg(env, cur_regs(env), value_regno, PTR_TO_BTF_ID, kptr_field->kptr.btf,
				kptr_field->kptr.btf_id, btf_ld_kptr_type(env, kptr_field));
	} else if (class == BPF_STX) {
		val_reg = reg_state(env, value_regno);
		if (!register_is_null(val_reg) &&
		    map_kptr_match_type(env, kptr_field, val_reg, value_regno))
			return -EACCES;
	} else if (class == BPF_ST) {
		if (insn->imm) {
			verbose(env, "BPF_ST imm must be 0 when storing to kptr at off=%u\n",
				kptr_field->offset);
			return -EACCES;
		}
	} else {
		verbose(env, "kptr in map can only be accessed using BPF_LDX/BPF_STX/BPF_ST\n");
		return -EACCES;
	}
	return 0;
}

/* check read/write into a map element with possible variable offset */
static int check_map_access(struct bpf_verifier_env *env, u32 regno,
			    int off, int size, bool zero_size_allowed,
			    enum bpf_access_src src)
{
	struct bpf_verifier_state *vstate = env->cur_state;
	struct bpf_func_state *state = vstate->frame[vstate->curframe];
	struct bpf_reg_state *reg = &state->regs[regno];
	struct bpf_map *map = reg->map_ptr;
	struct btf_record *rec;
	int err, i;

	err = check_mem_region_access(env, regno, off, size, map->value_size,
				      zero_size_allowed);
	if (err)
		return err;

	if (IS_ERR_OR_NULL(map->record))
		return 0;
	rec = map->record;
	for (i = 0; i < rec->cnt; i++) {
		struct btf_field *field = &rec->fields[i];
		u32 p = field->offset;

		/* If any part of a field  can be touched by load/store, reject
		 * this program. To check that [x1, x2) overlaps with [y1, y2),
		 * it is sufficient to check x1 < y2 && y1 < x2.
		 */
		if (reg->smin_value + off < p + field->size &&
		    p < reg->umax_value + off + size) {
			switch (field->type) {
			case BPF_KPTR_UNREF:
			case BPF_KPTR_REF:
			case BPF_KPTR_PERCPU:
				if (src != ACCESS_DIRECT) {
					verbose(env, "kptr cannot be accessed indirectly by helper\n");
					return -EACCES;
				}
				if (!tnum_is_const(reg->var_off)) {
					verbose(env, "kptr access cannot have variable offset\n");
					return -EACCES;
				}
				if (p != off + reg->var_off.value) {
					verbose(env, "kptr access misaligned expected=%u off=%llu\n",
						p, off + reg->var_off.value);
					return -EACCES;
				}
				if (size != bpf_size_to_bytes(BPF_DW)) {
					verbose(env, "kptr access size must be BPF_DW\n");
					return -EACCES;
				}
				break;
			default:
				verbose(env, "%s cannot be accessed directly by load/store\n",
					btf_field_type_name(field->type));
				return -EACCES;
			}
		}
	}
	return 0;
}

#define MAX_PACKET_OFF 0xffff

static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
				       const struct bpf_call_arg_meta *meta,
				       enum bpf_access_type t)
{
	enum bpf_prog_type prog_type = resolve_prog_type(env->prog);

	switch (prog_type) {
	/* Program types only with direct read access go here! */
	case BPF_PROG_TYPE_LWT_IN:
	case BPF_PROG_TYPE_LWT_OUT:
	case BPF_PROG_TYPE_LWT_SEG6LOCAL:
	case BPF_PROG_TYPE_SK_REUSEPORT:
	case BPF_PROG_TYPE_FLOW_DISSECTOR:
	case BPF_PROG_TYPE_CGROUP_SKB:
		if (t == BPF_WRITE)
			return false;
		fallthrough;

	/* Program types with direct read + write access go here! */
	case BPF_PROG_TYPE_SCHED_CLS:
	case BPF_PROG_TYPE_SCHED_ACT:
	case BPF_PROG_TYPE_XDP:
	case BPF_PROG_TYPE_LWT_XMIT:
	case BPF_PROG_TYPE_SK_SKB:
	case BPF_PROG_TYPE_SK_MSG:
		if (meta)
			return meta->pkt_access;

		env->seen_direct_write = true;
		return true;

	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
		if (t == BPF_WRITE)
			env->seen_direct_write = true;

		return true;

	default:
		return false;
	}
}

static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
			       int size, bool zero_size_allowed)
{
	struct bpf_reg_state *regs = cur_regs(env);
	struct bpf_reg_state *reg = &regs[regno];
	int err;

	/* We may have added a variable offset to the packet pointer; but any
	 * reg->range we have comes after that.  We are only checking the fixed
	 * offset.
	 */

	/* We don't allow negative numbers, because we aren't tracking enough
	 * detail to prove they're safe.
	 */
	if (reg->smin_value < 0) {
		verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
			regno);
		return -EACCES;
	}

	err = reg->range < 0 ? -EINVAL :
	      __check_mem_access(env, regno, off, size, reg->range,
				 zero_size_allowed);
	if (err) {
		verbose(env, "R%d offset is outside of the packet\n", regno);
		return err;
	}

	/* __check_mem_access has made sure "off + size - 1" is within u16.
	 * reg->umax_value can't be bigger than MAX_PACKET_OFF which is 0xffff,
	 * otherwise find_good_pkt_pointers would have refused to set range info
	 * that __check_mem_access would have rejected this pkt access.
	 * Therefore, "off + reg->umax_value + size - 1" won't overflow u32.
	 */
	env->prog->aux->max_pkt_offset =
		max_t(u32, env->prog->aux->max_pkt_offset,
		      off + reg->umax_value + size - 1);

	return err;
}

/* check access to 'struct bpf_context' fields.  Supports fixed offsets only */
static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
			    enum bpf_access_type t, enum bpf_reg_type *reg_type,
			    struct btf **btf, u32 *btf_id, bool *is_retval, bool is_ldsx)
{
	struct bpf_insn_access_aux info = {
		.reg_type = *reg_type,
		.log = &env->log,
		.is_retval = false,
		.is_ldsx = is_ldsx,
	};

	if (env->ops->is_valid_access &&
	    env->ops->is_valid_access(off, size, t, env->prog, &info)) {
		/* A non zero info.ctx_field_size indicates that this field is a
		 * candidate for later verifier transformation to load the whole
		 * field and then apply a mask when accessed with a narrower
		 * access than actual ctx access size. A zero info.ctx_field_size
		 * will only allow for whole field access and rejects any other
		 * type of narrower access.
		 */
		*reg_type = info.reg_type;
		*is_retval = info.is_retval;

		if (base_type(*reg_type) == PTR_TO_BTF_ID) {
			*btf = info.btf;
			*btf_id = info.btf_id;
		} else {
			env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
		}
		/* remember the offset of last byte accessed in ctx */
		if (env->prog->aux->max_ctx_offset < off + size)
			env->prog->aux->max_ctx_offset = off + size;
		return 0;
	}

	verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size);
	return -EACCES;
}

static int check_flow_keys_access(struct bpf_verifier_env *env, int off,
				  int size)
{
	if (size < 0 || off < 0 ||
	    (u64)off + size > sizeof(struct bpf_flow_keys)) {
		verbose(env, "invalid access to flow keys off=%d size=%d\n",
			off, size);
		return -EACCES;
	}
	return 0;
}

static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
			     u32 regno, int off, int size,
			     enum bpf_access_type t)
{
	struct bpf_reg_state *regs = cur_regs(env);
	struct bpf_reg_state *reg = &regs[regno];
	struct bpf_insn_access_aux info = {};
	bool valid;

	if (reg->smin_value < 0) {
		verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
			regno);
		return -EACCES;
	}

	switch (reg->type) {
	case PTR_TO_SOCK_COMMON:
		valid = bpf_sock_common_is_valid_access(off, size, t, &info);
		break;
	case PTR_TO_SOCKET:
		valid = bpf_sock_is_valid_access(off, size, t, &info);
		break;
	case PTR_TO_TCP_SOCK:
		valid = bpf_tcp_sock_is_valid_access(off, size, t, &info);
		break;
	case PTR_TO_XDP_SOCK:
		valid = bpf_xdp_sock_is_valid_access(off, size, t, &info);
		break;
	default:
		valid = false;
	}


	if (valid) {
		env->insn_aux_data[insn_idx].ctx_field_size =
			info.ctx_field_size;
		return 0;
	}

	verbose(env, "R%d invalid %s access off=%d size=%d\n",
		regno, reg_type_str(env, reg->type), off, size);

	return -EACCES;
}

static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
{
	return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno));
}

static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
{
	const struct bpf_reg_state *reg = reg_state(env, regno);

	return reg->type == PTR_TO_CTX;
}

static bool is_sk_reg(struct bpf_verifier_env *env, int regno)
{
	const struct bpf_reg_state *reg = reg_state(env, regno);

	return type_is_sk_pointer(reg->type);
}

static bool is_pkt_reg(struct bpf_verifier_env *env, int regno)
{
	const struct bpf_reg_state *reg = reg_state(env, regno);

	return type_is_pkt_pointer(reg->type);
}

static bool is_flow_key_reg(struct bpf_verifier_env *env, int regno)
{
	const struct bpf_reg_state *reg = reg_state(env, regno);

	/* Separate to is_ctx_reg() since we still want to allow BPF_ST here. */
	return reg->type == PTR_TO_FLOW_KEYS;
}

static bool is_arena_reg(struct bpf_verifier_env *env, int regno)
{
	const struct bpf_reg_state *reg = reg_state(env, regno);

	return reg->type == PTR_TO_ARENA;
}

static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = {
#ifdef CONFIG_NET
	[PTR_TO_SOCKET] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK],
	[PTR_TO_SOCK_COMMON] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
	[PTR_TO_TCP_SOCK] = &btf_sock_ids[BTF_SOCK_TYPE_TCP],
#endif
	[CONST_PTR_TO_MAP] = btf_bpf_map_id,
};

static bool is_trusted_reg(const struct bpf_reg_state *reg)
{
	/* A referenced register is always trusted. */
	if (reg->ref_obj_id)
		return true;

	/* Types listed in the reg2btf_ids are always trusted */
	if (reg2btf_ids[base_type(reg->type)] &&
	    !bpf_type_has_unsafe_modifiers(reg->type))
		return true;

	/* If a register is not referenced, it is trusted if it has the
	 * MEM_ALLOC or PTR_TRUSTED type modifiers, and no others. Some of the
	 * other type modifiers may be safe, but we elect to take an opt-in
	 * approach here as some (e.g. PTR_UNTRUSTED and PTR_MAYBE_NULL) are
	 * not.
	 *
	 * Eventually, we should make PTR_TRUSTED the single source of truth
	 * for whether a register is trusted.
	 */
	return type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS &&
	       !bpf_type_has_unsafe_modifiers(reg->type);
}

static bool is_rcu_reg(const struct bpf_reg_state *reg)
{
	return reg->type & MEM_RCU;
}

static void clear_trusted_flags(enum bpf_type_flag *flag)
{
	*flag &= ~(BPF_REG_TRUSTED_MODIFIERS | MEM_RCU);
}

static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
				   const struct bpf_reg_state *reg,
				   int off, int size, bool strict)
{
	struct tnum reg_off;
	int ip_align;

	/* Byte size accesses are always allowed. */
	if (!strict || size == 1)
		return 0;

	/* For platforms that do not have a Kconfig enabling
	 * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
	 * NET_IP_ALIGN is universally set to '2'.  And on platforms
	 * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
	 * to this code only in strict mode where we want to emulate
	 * the NET_IP_ALIGN==2 checking.  Therefore use an
	 * unconditional IP align value of '2'.
	 */
	ip_align = 2;

	reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off));
	if (!tnum_is_aligned(reg_off, size)) {
		char tn_buf[48];

		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
		verbose(env,
			"misaligned packet access off %d+%s+%d+%d size %d\n",
			ip_align, tn_buf, reg->off, off, size);
		return -EACCES;
	}

	return 0;
}

static int check_generic_ptr_alignment(struct bpf_verifier_env *env,
				       const struct bpf_reg_state *reg,
				       const char *pointer_desc,
				       int off, int size, bool strict)
{
	struct tnum reg_off;

	/* Byte size accesses are always allowed. */
	if (!strict || size == 1)
		return 0;

	reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off));
	if (!tnum_is_aligned(reg_off, size)) {
		char tn_buf[48];

		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
		verbose(env, "misaligned %saccess off %s+%d+%d size %d\n",
			pointer_desc, tn_buf, reg->off, off, size);
		return -EACCES;
	}

	return 0;
}

static int check_ptr_alignment(struct bpf_verifier_env *env,
			       const struct bpf_reg_state *reg, int off,
			       int size, bool strict_alignment_once)
{
	bool strict = env->strict_alignment || strict_alignment_once;
	const char *pointer_desc = "";

	switch (reg->type) {
	case PTR_TO_PACKET:
	case PTR_TO_PACKET_META:
		/* Special case, because of NET_IP_ALIGN. Given metadata sits
		 * right in front, treat it the very same way.
		 */
		return check_pkt_ptr_alignment(env, reg, off, size, strict);
	case PTR_TO_FLOW_KEYS:
		pointer_desc = "flow keys ";
		break;
	case PTR_TO_MAP_KEY:
		pointer_desc = "key ";
		break;
	case PTR_TO_MAP_VALUE:
		pointer_desc = "value ";
		break;
	case PTR_TO_CTX:
		pointer_desc = "context ";
		break;
	case PTR_TO_STACK:
		pointer_desc = "stack ";
		/* The stack spill tracking logic in check_stack_write_fixed_off()
		 * and check_stack_read_fixed_off() relies on stack accesses being
		 * aligned.
		 */
		strict = true;
		break;
	case PTR_TO_SOCKET:
		pointer_desc = "sock ";
		break;
	case PTR_TO_SOCK_COMMON:
		pointer_desc = "sock_common ";
		break;
	case PTR_TO_TCP_SOCK:
		pointer_desc = "tcp_sock ";
		break;
	case PTR_TO_XDP_SOCK:
		pointer_desc = "xdp_sock ";
		break;
	case PTR_TO_ARENA:
		return 0;
	default:
		break;
	}
	return check_generic_ptr_alignment(env, reg, pointer_desc, off, size,
					   strict);
}

static int round_up_stack_depth(struct bpf_verifier_env *env, int stack_depth)
{
	if (env->prog->jit_requested)
		return round_up(stack_depth, 16);

	/* round up to 32-bytes, since this is granularity
	 * of interpreter stack size
	 */
	return round_up(max_t(u32, stack_depth, 1), 32);
}

/* starting from main bpf function walk all instructions of the function
 * and recursively walk all callees that given function can call.
 * Ignore jump and exit insns.
 * Since recursion is prevented by check_cfg() this algorithm
 * only needs a local stack of MAX_CALL_FRAMES to remember callsites
 */
static int check_max_stack_depth_subprog(struct bpf_verifier_env *env, int idx)
{
	struct bpf_subprog_info *subprog = env->subprog_info;
	struct bpf_insn *insn = env->prog->insnsi;
	int depth = 0, frame = 0, i, subprog_end;
	bool tail_call_reachable = false;
	int ret_insn[MAX_CALL_FRAMES];
	int ret_prog[MAX_CALL_FRAMES];
	int j;

	i = subprog[idx].start;
process_func:
	/* protect against potential stack overflow that might happen when
	 * bpf2bpf calls get combined with tailcalls. Limit the caller's stack
	 * depth for such case down to 256 so that the worst case scenario
	 * would result in 8k stack size (32 which is tailcall limit * 256 =
	 * 8k).
	 *
	 * To get the idea what might happen, see an example:
	 * func1 -> sub rsp, 128
	 *  subfunc1 -> sub rsp, 256
	 *  tailcall1 -> add rsp, 256
	 *   func2 -> sub rsp, 192 (total stack size = 128 + 192 = 320)
	 *   subfunc2 -> sub rsp, 64
	 *   subfunc22 -> sub rsp, 128
	 *   tailcall2 -> add rsp, 128
	 *    func3 -> sub rsp, 32 (total stack size 128 + 192 + 64 + 32 = 416)
	 *
	 * tailcall will unwind the current stack frame but it will not get rid
	 * of caller's stack as shown on the example above.
	 */
	if (idx && subprog[idx].has_tail_call && depth >= 256) {
		verbose(env,
			"tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n",
			depth);
		return -EACCES;
	}
	depth += round_up_stack_depth(env, subprog[idx].stack_depth);
	if (depth > MAX_BPF_STACK) {
		verbose(env, "combined stack size of %d calls is %d. Too large\n",
			frame + 1, depth);
		return -EACCES;
	}
continue_func:
	subprog_end = subprog[idx + 1].start;
	for (; i < subprog_end; i++) {
		int next_insn, sidx;

		if (bpf_pseudo_kfunc_call(insn + i) && !insn[i].off) {
			bool err = false;

			if (!is_bpf_throw_kfunc(insn + i))
				continue;
			if (subprog[idx].is_cb)
				err = true;
			for (int c = 0; c < frame && !err; c++) {
				if (subprog[ret_prog[c]].is_cb) {
					err = true;
					break;
				}
			}
			if (!err)
				continue;
			verbose(env,
				"bpf_throw kfunc (insn %d) cannot be called from callback subprog %d\n",
				i, idx);
			return -EINVAL;
		}

		if (!bpf_pseudo_call(insn + i) && !bpf_pseudo_func(insn + i))
			continue;
		/* remember insn and function to return to */
		ret_insn[frame] = i + 1;
		ret_prog[frame] = idx;

		/* find the callee */
		next_insn = i + insn[i].imm + 1;
		sidx = find_subprog(env, next_insn);
		if (sidx < 0) {
			WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
				  next_insn);
			return -EFAULT;
		}
		if (subprog[sidx].is_async_cb) {
			if (subprog[sidx].has_tail_call) {
				verbose(env, "verifier bug. subprog has tail_call and async cb\n");
				return -EFAULT;
			}
			/* async callbacks don't increase bpf prog stack size unless called directly */
			if (!bpf_pseudo_call(insn + i))
				continue;
			if (subprog[sidx].is_exception_cb) {
				verbose(env, "insn %d cannot call exception cb directly\n", i);
				return -EINVAL;
			}
		}
		i = next_insn;
		idx = sidx;

		if (subprog[idx].has_tail_call)
			tail_call_reachable = true;

		frame++;
		if (frame >= MAX_CALL_FRAMES) {
			verbose(env, "the call stack of %d frames is too deep !\n",
				frame);
			return -E2BIG;
		}
		goto process_func;
	}
	/* if tail call got detected across bpf2bpf calls then mark each of the
	 * currently present subprog frames as tail call reachable subprogs;
	 * this info will be utilized by JIT so that we will be preserving the
	 * tail call counter throughout bpf2bpf calls combined with tailcalls
	 */
	if (tail_call_reachable)
		for (j = 0; j < frame; j++) {
			if (subprog[ret_prog[j]].is_exception_cb) {
				verbose(env, "cannot tail call within exception cb\n");
				return -EINVAL;
			}
			subprog[ret_prog[j]].tail_call_reachable = true;
		}
	if (subprog[0].tail_call_reachable)
		env->prog->aux->tail_call_reachable = true;

	/* end of for() loop means the last insn of the 'subprog'
	 * was reached. Doesn't matter whether it was JA or EXIT
	 */
	if (frame == 0)
		return 0;
	depth -= round_up_stack_depth(env, subprog[idx].stack_depth);
	frame--;
	i = ret_insn[frame];
	idx = ret_prog[frame];
	goto continue_func;
}

static int check_max_stack_depth(struct bpf_verifier_env *env)
{
	struct bpf_subprog_info *si = env->subprog_info;
	int ret;

	for (int i = 0; i < env->subprog_cnt; i++) {
		if (!i || si[i].is_async_cb) {
			ret = check_max_stack_depth_subprog(env, i);
			if (ret < 0)
				return ret;
		}
		continue;
	}
	return 0;
}

#ifndef CONFIG_BPF_JIT_ALWAYS_ON
static int get_callee_stack_depth(struct bpf_verifier_env *env,
				  const struct bpf_insn *insn, int idx)
{
	int start = idx + insn->imm + 1, subprog;

	subprog = find_subprog(env, start);
	if (subprog < 0) {
		WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
			  start);
		return -EFAULT;
	}
	return env->subprog_info[subprog].stack_depth;
}
#endif

static int __check_buffer_access(struct bpf_verifier_env *env,
				 const char *buf_info,
				 const struct bpf_reg_state *reg,
				 int regno, int off, int size)
{
	if (off < 0) {
		verbose(env,
			"R%d invalid %s buffer access: off=%d, size=%d\n",
			regno, buf_info, off, size);
		return -EACCES;
	}
	if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
		char tn_buf[48];

		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
		verbose(env,
			"R%d invalid variable buffer offset: off=%d, var_off=%s\n",
			regno, off, tn_buf);
		return -EACCES;
	}

	return 0;
}

static int check_tp_buffer_access(struct bpf_verifier_env *env,
				  const struct bpf_reg_state *reg,
				  int regno, int off, int size)
{
	int err;

	err = __check_buffer_access(env, "tracepoint", reg, regno, off, size);
	if (err)
		return err;

	if (off + size > env->prog->aux->max_tp_access)
		env->prog->aux->max_tp_access = off + size;

	return 0;
}

static int check_buffer_access(struct bpf_verifier_env *env,
			       const struct bpf_reg_state *reg,
			       int regno, int off, int size,
			       bool zero_size_allowed,
			       u32 *max_access)
{
	const char *buf_info = type_is_rdonly_mem(reg->type) ? "rdonly" : "rdwr";
	int err;

	err = __check_buffer_access(env, buf_info, reg, regno, off, size);
	if (err)
		return err;

	if (off + size > *max_access)
		*max_access = off + size;

	return 0;
}

/* BPF architecture zero extends alu32 ops into 64-bit registesr */
static void zext_32_to_64(struct bpf_reg_state *reg)
{
	reg->var_off = tnum_subreg(reg->var_off);
	__reg_assign_32_into_64(reg);
}

/* truncate register to smaller size (in bytes)
 * must be called with size < BPF_REG_SIZE
 */
static void coerce_reg_to_size(struct bpf_reg_state *reg, int size)
{
	u64 mask;

	/* clear high bits in bit representation */
	reg->var_off = tnum_cast(reg->var_off, size);

	/* fix arithmetic bounds */
	mask = ((u64)1 << (size * 8)) - 1;
	if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) {
		reg->umin_value &= mask;
		reg->umax_value &= mask;
	} else {
		reg->umin_value = 0;
		reg->umax_value = mask;
	}
	reg->smin_value = reg->umin_value;
	reg->smax_value = reg->umax_value;

	/* If size is smaller than 32bit register the 32bit register
	 * values are also truncated so we push 64-bit bounds into
	 * 32-bit bounds. Above were truncated < 32-bits already.
	 */
	if (size < 4)
		__mark_reg32_unbounded(reg);

	reg_bounds_sync(reg);
}

static void set_sext64_default_val(struct bpf_reg_state *reg, int size)
{
	if (size == 1) {
		reg->smin_value = reg->s32_min_value = S8_MIN;
		reg->smax_value = reg->s32_max_value = S8_MAX;
	} else if (size == 2) {
		reg->smin_value = reg->s32_min_value = S16_MIN;
		reg->smax_value = reg->s32_max_value = S16_MAX;
	} else {
		/* size == 4 */
		reg->smin_value = reg->s32_min_value = S32_MIN;
		reg->smax_value = reg->s32_max_value = S32_MAX;
	}
	reg->umin_value = reg->u32_min_value = 0;
	reg->umax_value = U64_MAX;
	reg->u32_max_value = U32_MAX;
	reg->var_off = tnum_unknown;
}

static void coerce_reg_to_size_sx(struct bpf_reg_state *reg, int size)
{
	s64 init_s64_max, init_s64_min, s64_max, s64_min, u64_cval;
	u64 top_smax_value, top_smin_value;
	u64 num_bits = size * 8;

	if (tnum_is_const(reg->var_off)) {
		u64_cval = reg->var_off.value;
		if (size == 1)
			reg->var_off = tnum_const((s8)u64_cval);
		else if (size == 2)
			reg->var_off = tnum_const((s16)u64_cval);
		else
			/* size == 4 */
			reg->var_off = tnum_const((s32)u64_cval);

		u64_cval = reg->var_off.value;
		reg->smax_value = reg->smin_value = u64_cval;
		reg->umax_value = reg->umin_value = u64_cval;
		reg->s32_max_value = reg->s32_min_value = u64_cval;
		reg->u32_max_value = reg->u32_min_value = u64_cval;
		return;
	}

	top_smax_value = ((u64)reg->smax_value >> num_bits) << num_bits;
	top_smin_value = ((u64)reg->smin_value >> num_bits) << num_bits;

	if (top_smax_value != top_smin_value)
		goto out;

	/* find the s64_min and s64_min after sign extension */
	if (size == 1) {
		init_s64_max = (s8)reg->smax_value;
		init_s64_min = (s8)reg->smin_value;
	} else if (size == 2) {
		init_s64_max = (s16)reg->smax_value;
		init_s64_min = (s16)reg->smin_value;
	} else {
		init_s64_max = (s32)reg->smax_value;
		init_s64_min = (s32)reg->smin_value;
	}

	s64_max = max(init_s64_max, init_s64_min);
	s64_min = min(init_s64_max, init_s64_min);

	/* both of s64_max/s64_min positive or negative */
	if ((s64_max >= 0) == (s64_min >= 0)) {
		reg->s32_min_value = reg->smin_value = s64_min;
		reg->s32_max_value = reg->smax_value = s64_max;
		reg->u32_min_value = reg->umin_value = s64_min;
		reg->u32_max_value = reg->umax_value = s64_max;
		reg->var_off = tnum_range(s64_min, s64_max);
		return;
	}

out:
	set_sext64_default_val(reg, size);
}

static void set_sext32_default_val(struct bpf_reg_state *reg, int size)
{
	if (size == 1) {
		reg->s32_min_value = S8_MIN;
		reg->s32_max_value = S8_MAX;
	} else {
		/* size == 2 */
		reg->s32_min_value = S16_MIN;
		reg->s32_max_value = S16_MAX;
	}
	reg->u32_min_value = 0;
	reg->u32_max_value = U32_MAX;
	reg->var_off = tnum_subreg(tnum_unknown);
}

static void coerce_subreg_to_size_sx(struct bpf_reg_state *reg, int size)
{
	s32 init_s32_max, init_s32_min, s32_max, s32_min, u32_val;
	u32 top_smax_value, top_smin_value;
	u32 num_bits = size * 8;

	if (tnum_is_const(reg->var_off)) {
		u32_val = reg->var_off.value;
		if (size == 1)
			reg->var_off = tnum_const((s8)u32_val);
		else
			reg->var_off = tnum_const((s16)u32_val);

		u32_val = reg->var_off.value;
		reg->s32_min_value = reg->s32_max_value = u32_val;
		reg->u32_min_value = reg->u32_max_value = u32_val;
		return;
	}

	top_smax_value = ((u32)reg->s32_max_value >> num_bits) << num_bits;
	top_smin_value = ((u32)reg->s32_min_value >> num_bits) << num_bits;

	if (top_smax_value != top_smin_value)
		goto out;

	/* find the s32_min and s32_min after sign extension */
	if (size == 1) {
		init_s32_max = (s8)reg->s32_max_value;
		init_s32_min = (s8)reg->s32_min_value;
	} else {
		/* size == 2 */
		init_s32_max = (s16)reg->s32_max_value;
		init_s32_min = (s16)reg->s32_min_value;
	}
	s32_max = max(init_s32_max, init_s32_min);
	s32_min = min(init_s32_max, init_s32_min);

	if ((s32_min >= 0) == (s32_max >= 0)) {
		reg->s32_min_value = s32_min;
		reg->s32_max_value = s32_max;
		reg->u32_min_value = (u32)s32_min;
		reg->u32_max_value = (u32)s32_max;
		reg->var_off = tnum_subreg(tnum_range(s32_min, s32_max));
		return;
	}

out:
	set_sext32_default_val(reg, size);
}

static bool bpf_map_is_rdonly(const struct bpf_map *map)
{
	/* A map is considered read-only if the following condition are true:
	 *
	 * 1) BPF program side cannot change any of the map content. The
	 *    BPF_F_RDONLY_PROG flag is throughout the lifetime of a map
	 *    and was set at map creation time.
	 * 2) The map value(s) have been initialized from user space by a
	 *    loader and then "frozen", such that no new map update/delete
	 *    operations from syscall side are possible for the rest of
	 *    the map's lifetime from that point onwards.
	 * 3) Any parallel/pending map update/delete operations from syscall
	 *    side have been completed. Only after that point, it's safe to
	 *    assume that map value(s) are immutable.
	 */
	return (map->map_flags & BPF_F_RDONLY_PROG) &&
	       READ_ONCE(map->frozen) &&
	       !bpf_map_write_active(map);
}

static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val,
			       bool is_ldsx)
{
	void *ptr;
	u64 addr;
	int err;

	err = map->ops->map_direct_value_addr(map, &addr, off);
	if (err)
		return err;
	ptr = (void *)(long)addr + off;

	switch (size) {
	case sizeof(u8):
		*val = is_ldsx ? (s64)*(s8 *)ptr : (u64)*(u8 *)ptr;
		break;
	case sizeof(u16):
		*val = is_ldsx ? (s64)*(s16 *)ptr : (u64)*(u16 *)ptr;
		break;
	case sizeof(u32):
		*val = is_ldsx ? (s64)*(s32 *)ptr : (u64)*(u32 *)ptr;
		break;
	case sizeof(u64):
		*val = *(u64 *)ptr;
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

#define BTF_TYPE_SAFE_RCU(__type)  __PASTE(__type, __safe_rcu)
#define BTF_TYPE_SAFE_RCU_OR_NULL(__type)  __PASTE(__type, __safe_rcu_or_null)
#define BTF_TYPE_SAFE_TRUSTED(__type)  __PASTE(__type, __safe_trusted)
#define BTF_TYPE_SAFE_TRUSTED_OR_NULL(__type)  __PASTE(__type, __safe_trusted_or_null)

/*
 * Allow list few fields as RCU trusted or full trusted.
 * This logic doesn't allow mix tagging and will be removed once GCC supports
 * btf_type_tag.
 */

/* RCU trusted: these fields are trusted in RCU CS and never NULL */
BTF_TYPE_SAFE_RCU(struct task_struct) {
	const cpumask_t *cpus_ptr;
	struct css_set __rcu *cgroups;
	struct task_struct __rcu *real_parent;
	struct task_struct *group_leader;
};

BTF_TYPE_SAFE_RCU(struct cgroup) {
	/* cgrp->kn is always accessible as documented in kernel/cgroup/cgroup.c */
	struct kernfs_node *kn;
};

BTF_TYPE_SAFE_RCU(struct css_set) {
	struct cgroup *dfl_cgrp;
};

/* RCU trusted: these fields are trusted in RCU CS and can be NULL */
BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct) {
	struct file __rcu *exe_file;
};

/* skb->sk, req->sk are not RCU protected, but we mark them as such
 * because bpf prog accessible sockets are SOCK_RCU_FREE.
 */
BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff) {
	struct sock *sk;
};

BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock) {
	struct sock *sk;
};

/* full trusted: these fields are trusted even outside of RCU CS and never NULL */
BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta) {
	struct seq_file *seq;
};

BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task) {
	struct bpf_iter_meta *meta;
	struct task_struct *task;
};

BTF_TYPE_SAFE_TRUSTED(struct linux_binprm) {
	struct file *file;
};

BTF_TYPE_SAFE_TRUSTED(struct file) {
	struct inode *f_inode;
};

BTF_TYPE_SAFE_TRUSTED(struct dentry) {
	/* no negative dentry-s in places where bpf can see it */
	struct inode *d_inode;
};

BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket) {
	struct sock *sk;
};

static bool type_is_rcu(struct bpf_verifier_env *env,
			struct bpf_reg_state *reg,
			const char *field_name, u32 btf_id)
{
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct task_struct));
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct cgroup));
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct css_set));

	return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu");
}

static bool type_is_rcu_or_null(struct bpf_verifier_env *env,
				struct bpf_reg_state *reg,
				const char *field_name, u32 btf_id)
{
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct));
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct sk_buff));
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU_OR_NULL(struct request_sock));

	return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu_or_null");
}

static bool type_is_trusted(struct bpf_verifier_env *env,
			    struct bpf_reg_state *reg,
			    const char *field_name, u32 btf_id)
{
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter_meta));
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task));
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct linux_binprm));
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct file));
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct dentry));

	return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted");
}

static bool type_is_trusted_or_null(struct bpf_verifier_env *env,
				    struct bpf_reg_state *reg,
				    const char *field_name, u32 btf_id)
{
	BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket));

	return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id,
					  "__safe_trusted_or_null");
}

static int check_ptr_to_btf_access(struct bpf_verifier_env *env,
				   struct bpf_reg_state *regs,
				   int regno, int off, int size,
				   enum bpf_access_type atype,
				   int value_regno)
{
	struct bpf_reg_state *reg = regs + regno;
	const struct btf_type *t = btf_type_by_id(reg->btf, reg->btf_id);
	const char *tname = btf_name_by_offset(reg->btf, t->name_off);
	const char *field_name = NULL;
	enum bpf_type_flag flag = 0;
	u32 btf_id = 0;
	int ret;

	if (!env->allow_ptr_leaks) {
		verbose(env,
			"'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
			tname);
		return -EPERM;
	}
	if (!env->prog->gpl_compatible && btf_is_kernel(reg->btf)) {
		verbose(env,
			"Cannot access kernel 'struct %s' from non-GPL compatible program\n",
			tname);
		return -EINVAL;
	}
	if (off < 0) {
		verbose(env,
			"R%d is ptr_%s invalid negative access: off=%d\n",
			regno, tname, off);
		return -EACCES;
	}
	if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
		char tn_buf[48];

		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
		verbose(env,
			"R%d is ptr_%s invalid variable offset: off=%d, var_off=%s\n",
			regno, tname, off, tn_buf);
		return -EACCES;
	}

	if (reg->type & MEM_USER) {
		verbose(env,
			"R%d is ptr_%s access user memory: off=%d\n",
			regno, tname, off);
		return -EACCES;
	}

	if (reg->type & MEM_PERCPU) {
		verbose(env,
			"R%d is ptr_%s access percpu memory: off=%d\n",
			regno, tname, off);
		return -EACCES;
	}

	if (env->ops->btf_struct_access && !type_is_alloc(reg->type) && atype == BPF_WRITE) {
		if (!btf_is_kernel(reg->btf)) {
			verbose(env, "verifier internal error: reg->btf must be kernel btf\n");
			return -EFAULT;
		}
		ret = env->ops->btf_struct_access(&env->log, reg, off, size);
	} else {
		/* Writes are permitted with default btf_struct_access for
		 * program allocated objects (which always have ref_obj_id > 0),
		 * but not for untrusted PTR_TO_BTF_ID | MEM_ALLOC.
		 */
		if (atype != BPF_READ && !type_is_ptr_alloc_obj(reg->type)) {
			verbose(env, "only read is supported\n");
			return -EACCES;
		}

		if (type_is_alloc(reg->type) && !type_is_non_owning_ref(reg->type) &&
		    !(reg->type & MEM_RCU) && !reg->ref_obj_id) {
			verbose(env, "verifier internal error: ref_obj_id for allocated object must be non-zero\n");
			return -EFAULT;
		}

		ret = btf_struct_access(&env->log, reg, off, size, atype, &btf_id, &flag, &field_name);
	}

	if (ret < 0)
		return ret;

	if (ret != PTR_TO_BTF_ID) {
		/* just mark; */

	} else if (type_flag(reg->type) & PTR_UNTRUSTED) {
		/* If this is an untrusted pointer, all pointers formed by walking it
		 * also inherit the untrusted flag.
		 */
		flag = PTR_UNTRUSTED;

	} else if (is_trusted_reg(reg) || is_rcu_reg(reg)) {
		/* By default any pointer obtained from walking a trusted pointer is no
		 * longer trusted, unless the field being accessed has explicitly been
		 * marked as inheriting its parent's state of trust (either full or RCU).
		 * For example:
		 * 'cgroups' pointer is untrusted if task->cgroups dereference
		 * happened in a sleepable program outside of bpf_rcu_read_lock()
		 * section. In a non-sleepable program it's trusted while in RCU CS (aka MEM_RCU).
		 * Note bpf_rcu_read_unlock() converts MEM_RCU pointers to PTR_UNTRUSTED.
		 *
		 * A regular RCU-protected pointer with __rcu tag can also be deemed
		 * trusted if we are in an RCU CS. Such pointer can be NULL.
		 */
		if (type_is_trusted(env, reg, field_name, btf_id)) {
			flag |= PTR_TRUSTED;
		} else if (type_is_trusted_or_null(env, reg, field_name, btf_id)) {
			flag |= PTR_TRUSTED | PTR_MAYBE_NULL;
		} else if (in_rcu_cs(env) && !type_may_be_null(reg->type)) {
			if (type_is_rcu(env, reg, field_name, btf_id)) {
				/* ignore __rcu tag and mark it MEM_RCU */
				flag |= MEM_RCU;
			} else if (flag & MEM_RCU ||
				   type_is_rcu_or_null(env, reg, field_name, btf_id)) {
				/* __rcu tagged pointers can be NULL */
				flag |= MEM_RCU | PTR_MAYBE_NULL;

				/* We always trust them */
				if (type_is_rcu_or_null(env, reg, field_name, btf_id) &&
				    flag & PTR_UNTRUSTED)
					flag &= ~PTR_UNTRUSTED;
			} else if (flag & (MEM_PERCPU | MEM_USER)) {
				/* keep as-is */
			} else {
				/* walking unknown pointers yields old deprecated PTR_TO_BTF_ID */
				clear_trusted_flags(&flag);
			}
		} else {
			/*
			 * If not in RCU CS or MEM_RCU pointer can be NULL then
			 * aggressively mark as untrusted otherwise such
			 * pointers will be plain PTR_TO_BTF_ID without flags
			 * and will be allowed to be passed into helpers for
			 * compat reasons.
			 */
			flag = PTR_UNTRUSTED;
		}
	} else {
		/* Old compat. Deprecated */
		clear_trusted_flags(&flag);
	}

	if (atype == BPF_READ && value_regno >= 0)
		mark_btf_ld_reg(env, regs, value_regno, ret, reg->btf, btf_id, flag);

	return 0;
}

static int check_ptr_to_map_access(struct bpf_verifier_env *env,
				   struct bpf_reg_state *regs,
				   int regno, int off, int size,
				   enum bpf_access_type atype,
				   int value_regno)
{
	struct bpf_reg_state *reg = regs + regno;
	struct bpf_map *map = reg->map_ptr;
	struct bpf_reg_state map_reg;
	enum bpf_type_flag flag = 0;
	const struct btf_type *t;
	const char *tname;
	u32 btf_id;
	int ret;

	if (!btf_vmlinux) {
		verbose(env, "map_ptr access not supported without CONFIG_DEBUG_INFO_BTF\n");
		return -ENOTSUPP;
	}

	if (!map->ops->map_btf_id || !*map->ops->map_btf_id) {
		verbose(env, "map_ptr access not supported for map type %d\n",
			map->map_type);
		return -ENOTSUPP;
	}

	t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id);
	tname = btf_name_by_offset(btf_vmlinux, t->name_off);

	if (!env->allow_ptr_leaks) {
		verbose(env,
			"'struct %s' access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
			tname);
		return -EPERM;
	}

	if (off < 0) {
		verbose(env, "R%d is %s invalid negative access: off=%d\n",
			regno, tname, off);
		return -EACCES;
	}

	if (atype != BPF_READ) {
		verbose(env, "only read from %s is supported\n", tname);
		return -EACCES;
	}

	/* Simulate access to a PTR_TO_BTF_ID */
	memset(&map_reg, 0, sizeof(map_reg));
	mark_btf_ld_reg(env, &map_reg, 0, PTR_TO_BTF_ID, btf_vmlinux, *map->ops->map_btf_id, 0);
	ret = btf_struct_access(&env->log, &map_reg, off, size, atype, &btf_id, &flag, NULL);
	if (ret < 0)
		return ret;

	if (value_regno >= 0)
		mark_btf_ld_reg(env, regs, value_regno, ret, btf_vmlinux, btf_id, flag);

	return 0;
}

/* Check that the stack access at the given offset is within bounds. The
 * maximum valid offset is -1.
 *
 * The minimum valid offset is -MAX_BPF_STACK for writes, and
 * -state->allocated_stack for reads.
 */
static int check_stack_slot_within_bounds(struct bpf_verifier_env *env,
                                          s64 off,
                                          struct bpf_func_state *state,
                                          enum bpf_access_type t)
{
	struct bpf_insn_aux_data *aux = &env->insn_aux_data[env->insn_idx];
	int min_valid_off, max_bpf_stack;

	/* If accessing instruction is a spill/fill from bpf_fastcall pattern,
	 * add room for all caller saved registers below MAX_BPF_STACK.
	 * In case if bpf_fastcall rewrite won't happen maximal stack depth
	 * would be checked by check_max_stack_depth_subprog().
	 */
	max_bpf_stack = MAX_BPF_STACK;
	if (aux->fastcall_pattern)
		max_bpf_stack += CALLER_SAVED_REGS * BPF_REG_SIZE;

	if (t == BPF_WRITE || env->allow_uninit_stack)
		min_valid_off = -max_bpf_stack;
	else
		min_valid_off = -state->allocated_stack;

	if (off < min_valid_off || off > -1)
		return -EACCES;
	return 0;
}

/* Check that the stack access at 'regno + off' falls within the maximum stack
 * bounds.
 *
 * 'off' includes `regno->offset`, but not its dynamic part (if any).
 */
static int check_stack_access_within_bounds(
		struct bpf_verifier_env *env,
		int regno, int off, int access_size,
		enum bpf_access_src src, enum bpf_access_type type)
{
	struct bpf_reg_state *regs = cur_regs(env);
	struct bpf_reg_state *reg = regs + regno;
	struct bpf_func_state *state = func(env, reg);
	s64 min_off, max_off;
	int err;
	char *err_extra;

	if (src == ACCESS_HELPER)
		/* We don't know if helpers are reading or writing (or both). */
		err_extra = " indirect access to";
	else if (type == BPF_READ)
		err_extra = " read from";
	else
		err_extra = " write to";

	if (tnum_is_const(reg->var_off)) {
		min_off = (s64)reg->var_off.value + off;
		max_off = min_off + access_size;
	} else {
		if (reg->smax_value >= BPF_MAX_VAR_OFF ||
		    reg->smin_value <= -BPF_MAX_VAR_OFF) {
			verbose(env, "invalid unbounded variable-offset%s stack R%d\n",
				err_extra, regno);
			return -EACCES;
		}
		min_off = reg->smin_value + off;
		max_off = reg->smax_value + off + access_size;
	}

	err = check_stack_slot_within_bounds(env, min_off, state, type);
	if (!err && max_off > 0)
		err = -EINVAL; /* out of stack access into non-negative offsets */
	if (!err && access_size < 0)
		/* access_size should not be negative (or overflow an int); others checks
		 * along the way should have prevented such an access.
		 */
		err = -EFAULT; /* invalid negative access size; integer overflow? */

	if (err) {
		if (tnum_is_const(reg->var_off)) {
			verbose(env, "invalid%s stack R%d off=%d size=%d\n",
				err_extra, regno, off, access_size);
		} else {
			char tn_buf[48];

			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
			verbose(env, "invalid variable-offset%s stack R%d var_off=%s off=%d size=%d\n",
				err_extra, regno, tn_buf, off, access_size);
		}
		return err;
	}

	/* Note that there is no stack access with offset zero, so the needed stack
	 * size is -min_off, not -min_off+1.
	 */
	return grow_stack_state(env, state, -min_off /* size */);
}

static bool get_func_retval_range(struct bpf_prog *prog,
				  struct bpf_retval_range *range)
{
	if (prog->type == BPF_PROG_TYPE_LSM &&
		prog->expected_attach_type == BPF_LSM_MAC &&
		!bpf_lsm_get_retval_range(prog, range)) {
		return true;
	}
	return false;
}

/* check whether memory at (regno + off) is accessible for t = (read | write)
 * if t==write, value_regno is a register which value is stored into memory
 * if t==read, value_regno is a register which will receive the value from memory
 * if t==write && value_regno==-1, some unknown value is stored into memory
 * if t==read && value_regno==-1, don't care what we read from memory
 */
static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno,
			    int off, int bpf_size, enum bpf_access_type t,
			    int value_regno, bool strict_alignment_once, bool is_ldsx)
{
	struct bpf_reg_state *regs = cur_regs(env);
	struct bpf_reg_state *reg = regs + regno;
	int size, err = 0;

	size = bpf_size_to_bytes(bpf_size);
	if (size < 0)
		return size;

	/* alignment checks will add in reg->off themselves */
	err = check_ptr_alignment(env, reg, off, size, strict_alignment_once);
	if (err)
		return err;

	/* for access checks, reg->off is just part of off */
	off += reg->off;

	if (reg->type == PTR_TO_MAP_KEY) {
		if (t == BPF_WRITE) {
			verbose(env, "write to change key R%d not allowed\n", regno);
			return -EACCES;
		}

		err = check_mem_region_access(env, regno, off, size,
					      reg->map_ptr->key_size, false);
		if (err)
			return err;
		if (value_regno >= 0)
			mark_reg_unknown(env, regs, value_regno);
	} else if (reg->type == PTR_TO_MAP_VALUE) {
		struct btf_field *kptr_field = NULL;

		if (t == BPF_WRITE && value_regno >= 0 &&
		    is_pointer_value(env, value_regno)) {
			verbose(env, "R%d leaks addr into map\n", value_regno);
			return -EACCES;
		}
		err = check_map_access_type(env, regno, off, size, t);
		if (err)
			return err;
		err = check_map_access(env, regno, off, size, false, ACCESS_DIRECT);
		if (err)
			return err;
		if (tnum_is_const(reg->var_off))
			kptr_field = btf_record_find(reg->map_ptr->record,
						     off + reg->var_off.value, BPF_KPTR);
		if (kptr_field) {
			err = check_map_kptr_access(env, regno, value_regno, insn_idx, kptr_field);
		} else if (t == BPF_READ && value_regno >= 0) {
			struct bpf_map *map = reg->map_ptr;

			/* if map is read-only, track its contents as scalars */
			if (tnum_is_const(reg->var_off) &&
			    bpf_map_is_rdonly(map) &&
			    map->ops->map_direct_value_addr) {
				int map_off = off + reg->var_off.value;
				u64 val = 0;

				err = bpf_map_direct_read(map, map_off, size,
							  &val, is_ldsx);
				if (err)
					return err;

				regs[value_regno].type = SCALAR_VALUE;
				__mark_reg_known(&regs[value_regno], val);
			} else {
				mark_reg_unknown(env, regs, value_regno);
			}
		}
	} else if (base_type(reg->type) == PTR_TO_MEM) {
		bool rdonly_mem = type_is_rdonly_mem(reg->type);

		if (type_may_be_null(reg->type)) {
			verbose(env, "R%d invalid mem access '%s'\n", regno,
				reg_type_str(env, reg->type));
			return -EACCES;
		}

		if (t == BPF_WRITE && rdonly_mem) {
			verbose(env, "R%d cannot write into %s\n",
				regno, reg_type_str(env, reg->type));
			return -EACCES;
		}

		if (t == BPF_WRITE && value_regno >= 0 &&
		    is_pointer_value(env, value_regno)) {
			verbose(env, "R%d leaks addr into mem\n", value_regno);
			return -EACCES;
		}

		err = check_mem_region_access(env, regno, off, size,
					      reg->mem_size, false);
		if (!err && value_regno >= 0 && (t == BPF_READ || rdonly_mem))
			mark_reg_unknown(env, regs, value_regno);
	} else if (reg->type == PTR_TO_CTX) {
		bool is_retval = false;
		struct bpf_retval_range range;
		enum bpf_reg_type reg_type = SCALAR_VALUE;
		struct btf *btf = NULL;
		u32 btf_id = 0;

		if (t == BPF_WRITE && value_regno >= 0 &&
		    is_pointer_value(env, value_regno)) {
			verbose(env, "R%d leaks addr into ctx\n", value_regno);
			return -EACCES;
		}

		err = check_ptr_off_reg(env, reg, regno);
		if (err < 0)
			return err;

		err = check_ctx_access(env, insn_idx, off, size, t, &reg_type, &btf,
				       &btf_id, &is_retval, is_ldsx);
		if (err)
			verbose_linfo(env, insn_idx, "; ");
		if (!err && t == BPF_READ && value_regno >= 0) {
			/* ctx access returns either a scalar, or a
			 * PTR_TO_PACKET[_META,_END]. In the latter
			 * case, we know the offset is zero.
			 */
			if (reg_type == SCALAR_VALUE) {
				if (is_retval && get_func_retval_range(env->prog, &range)) {
					err = __mark_reg_s32_range(env, regs, value_regno,
								   range.minval, range.maxval);
					if (err)
						return err;
				} else {
					mark_reg_unknown(env, regs, value_regno);
				}
			} else {
				mark_reg_known_zero(env, regs,
						    value_regno);
				if (type_may_be_null(reg_type))
					regs[value_regno].id = ++env->id_gen;
				/* A load of ctx field could have different
				 * actual load size with the one encoded in the
				 * insn. When the dst is PTR, it is for sure not
				 * a sub-register.
				 */
				regs[value_regno].subreg_def = DEF_NOT_SUBREG;
				if (base_type(reg_type) == PTR_TO_BTF_ID) {
					regs[value_regno].btf = btf;
					regs[value_regno].btf_id = btf_id;
				}
			}
			regs[value_regno].type = reg_type;
		}

	} else if (reg->type == PTR_TO_STACK) {
		/* Basic bounds checks. */
		err = check_stack_access_within_bounds(env, regno, off, size, ACCESS_DIRECT, t);
		if (err)
			return err;

		if (t == BPF_READ)
			err = check_stack_read(env, regno, off, size,
					       value_regno);
		else
			err = check_stack_write(env, regno, off, size,
						value_regno, insn_idx);
	} else if (reg_is_pkt_pointer(reg)) {
		if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
			verbose(env, "cannot write into packet\n");
			return -EACCES;
		}
		if (t == BPF_WRITE && value_regno >= 0 &&
		    is_pointer_value(env, value_regno)) {
			verbose(env, "R%d leaks addr into packet\n",
				value_regno);
			return -EACCES;
		}
		err = check_packet_access(env, regno, off, size, false);
		if (!err && t == BPF_READ && value_regno >= 0)
			mark_reg_unknown(env, regs, value_regno);
	} else if (reg->type == PTR_TO_FLOW_KEYS) {
		if (t == BPF_WRITE && value_regno >= 0 &&
		    is_pointer_value(env, value_regno)) {
			verbose(env, "R%d leaks addr into flow keys\n",
				value_regno);
			return -EACCES;
		}

		err = check_flow_keys_access(env, off, size);
		if (!err && t == BPF_READ && value_regno >= 0)
			mark_reg_unknown(env, regs, value_regno);
	} else if (type_is_sk_pointer(reg->type)) {
		if (t == BPF_WRITE) {
			verbose(env, "R%d cannot write into %s\n",
				regno, reg_type_str(env, reg->type));
			return -EACCES;
		}
		err = check_sock_access(env, insn_idx, regno, off, size, t);
		if (!err && value_regno >= 0)
			mark_reg_unknown(env, regs, value_regno);
	} else if (reg->type == PTR_TO_TP_BUFFER) {
		err = check_tp_buffer_access(env, reg, regno, off, size);
		if (!err && t == BPF_READ && value_regno >= 0)
			mark_reg_unknown(env, regs, value_regno);
	} else if (base_type(reg->type) == PTR_TO_BTF_ID &&
		   !type_may_be_null(reg->type)) {
		err = check_ptr_to_btf_access(env, regs, regno, off, size, t,
					      value_regno);
	} else if (reg->type == CONST_PTR_TO_MAP) {
		err = check_ptr_to_map_access(env, regs, regno, off, size, t,
					      value_regno);
	} else if (base_type(reg->type) == PTR_TO_BUF) {
		bool rdonly_mem = type_is_rdonly_mem(reg->type);
		u32 *max_access;

		if (rdonly_mem) {
			if (t == BPF_WRITE) {
				verbose(env, "R%d cannot write into %s\n",
					regno, reg_type_str(env, reg->type));
				return -EACCES;
			}
			max_access = &env->prog->aux->max_rdonly_access;
		} else {
			max_access = &env->prog->aux->max_rdwr_access;
		}

		err = check_buffer_access(env, reg, regno, off, size, false,
					  max_access);

		if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ))
			mark_reg_unknown(env, regs, value_regno);
	} else if (reg->type == PTR_TO_ARENA) {
		if (t == BPF_READ && value_regno >= 0)
			mark_reg_unknown(env, regs, value_regno);
	} else {
		verbose(env, "R%d invalid mem access '%s'\n", regno,
			reg_type_str(env, reg->type));
		return -EACCES;
	}

	if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ &&
	    regs[value_regno].type == SCALAR_VALUE) {
		if (!is_ldsx)
			/* b/h/w load zero-extends, mark upper bits as known 0 */
			coerce_reg_to_size(&regs[value_regno], size);
		else
			coerce_reg_to_size_sx(&regs[value_regno], size);
	}
	return err;
}

static int save_aux_ptr_type(struct bpf_verifier_env *env, enum bpf_reg_type type,
			     bool allow_trust_mismatch);

static int check_atomic(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
{
	int load_reg;
	int err;

	switch (insn->imm) {
	case BPF_ADD:
	case BPF_ADD | BPF_FETCH:
	case BPF_AND:
	case BPF_AND | BPF_FETCH:
	case BPF_OR:
	case BPF_OR | BPF_FETCH:
	case BPF_XOR:
	case BPF_XOR | BPF_FETCH:
	case BPF_XCHG:
	case BPF_CMPXCHG:
		break;
	default:
		verbose(env, "BPF_ATOMIC uses invalid atomic opcode %02x\n", insn->imm);
		return -EINVAL;
	}

	if (BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) {
		verbose(env, "invalid atomic operand size\n");
		return -EINVAL;
	}

	/* check src1 operand */
	err = check_reg_arg(env, insn->src_reg, SRC_OP);
	if (err)
		return err;

	/* check src2 operand */
	err = check_reg_arg(env, insn->dst_reg, SRC_OP);
	if (err)
		return err;

	if (insn->imm == BPF_CMPXCHG) {
		/* Check comparison of R0 with memory location */
		const u32 aux_reg = BPF_REG_0;

		err = check_reg_arg(env, aux_reg, SRC_OP);
		if (err)
			return err;

		if (is_pointer_value(env, aux_reg)) {
			verbose(env, "R%d leaks addr into mem\n", aux_reg);
			return -EACCES;
		}
	}

	if (is_pointer_value(env, insn->src_reg)) {
		verbose(env, "R%d leaks addr into mem\n", insn->src_reg);
		return -EACCES;
	}

	if (is_ctx_reg(env, insn->dst_reg) ||
	    is_pkt_reg(env, insn->dst_reg) ||
	    is_flow_key_reg(env, insn->dst_reg) ||
	    is_sk_reg(env, insn->dst_reg) ||
	    (is_arena_reg(env, insn->dst_reg) && !bpf_jit_supports_insn(insn, true))) {
		verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n",
			insn->dst_reg,
			reg_type_str(env, reg_state(env, insn->dst_reg)->type));
		return -EACCES;
	}

	if (insn->imm & BPF_FETCH) {
		if (insn->imm == BPF_CMPXCHG)
			load_reg = BPF_REG_0;
		else
			load_reg = insn->src_reg;

		/* check and record load of old value */
		err = check_reg_arg(env, load_reg, DST_OP);
		if (err)
			return err;
	} else {
		/* This instruction accesses a memory location but doesn't
		 * actually load it into a register.
		 */
		load_reg = -1;
	}

	/* Check whether we can read the memory, with second call for fetch
	 * case to simulate the register fill.
	 */
	err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
			       BPF_SIZE(insn->code), BPF_READ, -1, true, false);
	if (!err && load_reg >= 0)
		err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
				       BPF_SIZE(insn->code), BPF_READ, load_reg,
				       true, false);
	if (err)
		return err;

	if (is_arena_reg(env, insn->dst_reg)) {
		err = save_aux_ptr_type(env, PTR_TO_ARENA, false);
		if (err)
			return err;
	}
	/* Check whether we can write into the same memory. */
	err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
			       BPF_SIZE(insn->code), BPF_WRITE, -1, true, false);
	if (err)
		return err;
	return 0;
}

/* When register 'regno' is used to read the stack (either directly or through
 * a helper function) make sure that it's within stack boundary and, depending
 * on the access type and privileges, that all elements of the stack are
 * initialized.
 *
 * 'off' includes 'regno->off', but not its dynamic part (if any).
 *
 * All registers that have been spilled on the stack in the slots within the
 * read offsets are marked as read.
 */
static int check_stack_range_initialized(
		struct bpf_verifier_env *env, int regno, int off,
		int access_size, bool zero_size_allowed,
		enum bpf_access_src type, struct bpf_call_arg_meta *meta)
{
	struct bpf_reg_state *reg = reg_state(env, regno);
	struct bpf_func_state *state = func(env, reg);
	int err, min_off, max_off, i, j, slot, spi;
	char *err_extra = type == ACCESS_HELPER ? " indirect" : "";
	enum bpf_access_type bounds_check_type;
	/* Some accesses can write anything into the stack, others are
	 * read-only.
	 */
	bool clobber = false;

	if (access_size == 0 && !zero_size_allowed) {
		verbose(env, "invalid zero-sized read\n");
		return -EACCES;
	}

	if (type == ACCESS_HELPER) {
		/* The bounds checks for writes are more permissive than for
		 * reads. However, if raw_mode is not set, we'll do extra
		 * checks below.
		 */
		bounds_check_type = BPF_WRITE;
		clobber = true;
	} else {
		bounds_check_type = BPF_READ;
	}
	err = check_stack_access_within_bounds(env, regno, off, access_size,
					       type, bounds_check_type);
	if (err)
		return err;


	if (tnum_is_const(reg->var_off)) {
		min_off = max_off = reg->var_off.value + off;
	} else {
		/* Variable offset is prohibited for unprivileged mode for
		 * simplicity since it requires corresponding support in
		 * Spectre masking for stack ALU.
		 * See also retrieve_ptr_limit().
		 */
		if (!env->bypass_spec_v1) {
			char tn_buf[48];

			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
			verbose(env, "R%d%s variable offset stack access prohibited for !root, var_off=%s\n",
				regno, err_extra, tn_buf);
			return -EACCES;
		}
		/* Only initialized buffer on stack is allowed to be accessed
		 * with variable offset. With uninitialized buffer it's hard to
		 * guarantee that whole memory is marked as initialized on
		 * helper return since specific bounds are unknown what may
		 * cause uninitialized stack leaking.
		 */
		if (meta && meta->raw_mode)
			meta = NULL;

		min_off = reg->smin_value + off;
		max_off = reg->smax_value + off;
	}

	if (meta && meta->raw_mode) {
		/* Ensure we won't be overwriting dynptrs when simulating byte
		 * by byte access in check_helper_call using meta.access_size.
		 * This would be a problem if we have a helper in the future
		 * which takes:
		 *
		 *	helper(uninit_mem, len, dynptr)
		 *
		 * Now, uninint_mem may overlap with dynptr pointer. Hence, it
		 * may end up writing to dynptr itself when touching memory from
		 * arg 1. This can be relaxed on a case by case basis for known
		 * safe cases, but reject due to the possibilitiy of aliasing by
		 * default.
		 */
		for (i = min_off; i < max_off + access_size; i++) {
			int stack_off = -i - 1;

			spi = __get_spi(i);
			/* raw_mode may write past allocated_stack */
			if (state->allocated_stack <= stack_off)
				continue;
			if (state->stack[spi].slot_type[stack_off % BPF_REG_SIZE] == STACK_DYNPTR) {
				verbose(env, "potential write to dynptr at off=%d disallowed\n", i);
				return -EACCES;
			}
		}
		meta->access_size = access_size;
		meta->regno = regno;
		return 0;
	}

	for (i = min_off; i < max_off + access_size; i++) {
		u8 *stype;

		slot = -i - 1;
		spi = slot / BPF_REG_SIZE;
		if (state->allocated_stack <= slot) {
			verbose(env, "verifier bug: allocated_stack too small");
			return -EFAULT;
		}

		stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
		if (*stype == STACK_MISC)
			goto mark;
		if ((*stype == STACK_ZERO) ||
		    (*stype == STACK_INVALID && env->allow_uninit_stack)) {
			if (clobber) {
				/* helper can write anything into the stack */
				*stype = STACK_MISC;
			}
			goto mark;
		}

		if (is_spilled_reg(&state->stack[spi]) &&
		    (state->stack[spi].spilled_ptr.type == SCALAR_VALUE ||
		     env->allow_ptr_leaks)) {
			if (clobber) {
				__mark_reg_unknown(env, &state->stack[spi].spilled_ptr);
				for (j = 0; j < BPF_REG_SIZE; j++)
					scrub_spilled_slot(&state->stack[spi].slot_type[j]);
			}
			goto mark;
		}

		if (tnum_is_const(reg->var_off)) {
			verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n",
				err_extra, regno, min_off, i - min_off, access_size);
		} else {
			char tn_buf[48];

			tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
			verbose(env, "invalid%s read from stack R%d var_off %s+%d size %d\n",
				err_extra, regno, tn_buf, i - min_off, access_size);
		}
		return -EACCES;
mark:
		/* reading any byte out of 8-byte 'spill_slot' will cause
		 * the whole slot to be marked as 'read'
		 */
		mark_reg_read(env, &state->stack[spi].spilled_ptr,
			      state->stack[spi].spilled_ptr.parent,
			      REG_LIVE_READ64);
		/* We do not set REG_LIVE_WRITTEN for stack slot, as we can not
		 * be sure that whether stack slot is written to or not. Hence,
		 * we must still conservatively propagate reads upwards even if
		 * helper may write to the entire memory range.
		 */
	}
	return 0;
}

static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
				   int access_size, bool zero_size_allowed,
				   struct bpf_call_arg_meta *meta)
{
	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
	u32 *max_access;

	switch (base_type(reg->type)) {
	case PTR_TO_PACKET:
	case PTR_TO_PACKET_META:
		return check_packet_access(env, regno, reg->off, access_size,
					   zero_size_allowed);
	case PTR_TO_MAP_KEY:
		if (meta && meta->raw_mode) {
			verbose(env, "R%d cannot write into %s\n", regno,
				reg_type_str(env, reg->type));
			return -EACCES;
		}
		return check_mem_region_access(env, regno, reg->off, access_size,
					       reg->map_ptr->key_size, false);
	case PTR_TO_MAP_VALUE:
		if (check_map_access_type(env, regno, reg->off, access_size,
					  meta && meta->raw_mode ? BPF_WRITE :
					  BPF_READ))
			return -EACCES;
		return check_map_access(env, regno, reg->off, access_size,
					zero_size_allowed, ACCESS_HELPER);
	case PTR_TO_MEM:
		if (type_is_rdonly_mem(reg->type)) {
			if (meta && meta->raw_mode) {
				verbose(env, "R%d cannot write into %s\n", regno,
					reg_type_str(env, reg->type));
				return -EACCES;
			}
		}
		return check_mem_region_access(env, regno, reg->off,
					       access_size, reg->mem_size,
					       zero_size_allowed);
	case PTR_TO_BUF:
		if (type_is_rdonly_mem(reg->type)) {
			if (meta && meta->raw_mode) {
				verbose(env, "R%d cannot write into %s\n", regno,
					reg_type_str(env, reg->type));
				return -EACCES;
			}

			max_access = &env->prog->aux->max_rdonly_access;
		} else {
			max_access = &env->prog->aux->max_rdwr_access;
		}
		return check_buffer_access(env, reg, regno, reg->off,
					   access_size, zero_size_allowed,
					   max_access);
	case PTR_TO_STACK:
		return check_stack_range_initialized(
				env,
				regno, reg->off, access_size,
				zero_size_allowed, ACCESS_HELPER, meta);
	case PTR_TO_BTF_ID:
		return check_ptr_to_btf_access(env, regs, regno, reg->off,
					       access_size, BPF_READ, -1);
	case PTR_TO_CTX:
		/* in case the function doesn't know how to access the context,
		 * (because we are in a program of type SYSCALL for example), we
		 * can not statically check its size.
		 * Dynamically check it now.
		 */
		if (!env->ops->convert_ctx_access) {
			enum bpf_access_type atype = meta && meta->raw_mode ? BPF_WRITE : BPF_READ;
			int offset = access_size - 1;

			/* Allow zero-byte read from PTR_TO_CTX */
			if (access_size == 0)
				return zero_size_allowed ? 0 : -EACCES;

			return check_mem_access(env, env->insn_idx, regno, offset, BPF_B,
						atype, -1, false, false);
		}

		fallthrough;
	default: /* scalar_value or invalid ptr */
		/* Allow zero-byte read from NULL, regardless of pointer type */
		if (zero_size_allowed && access_size == 0 &&
		    register_is_null(reg))
			return 0;

		verbose(env, "R%d type=%s ", regno,
			reg_type_str(env, reg->type));
		verbose(env, "expected=%s\n", reg_type_str(env, PTR_TO_STACK));
		return -EACCES;
	}
}

/* verify arguments to helpers or kfuncs consisting of a pointer and an access
 * size.
 *
 * @regno is the register containing the access size. regno-1 is the register
 * containing the pointer.
 */
static int check_mem_size_reg(struct bpf_verifier_env *env,
			      struct bpf_reg_state *reg, u32 regno,
			      bool zero_size_allowed,
			      struct bpf_call_arg_meta *meta)
{
	int err;

	/* This is used to refine r0 return value bounds for helpers
	 * that enforce this value as an upper bound on return values.
	 * See do_refine_retval_range() for helpers that can refine
	 * the return value. C type of helper is u32 so we pull register
	 * bound from umax_value however, if negative verifier errors
	 * out. Only upper bounds can be learned because retval is an
	 * int type and negative retvals are allowed.
	 */
	meta->msize_max_value = reg->umax_value;

	/* The register is SCALAR_VALUE; the access check
	 * happens using its boundaries.
	 */
	if (!tnum_is_const(reg->var_off))
		/* For unprivileged variable accesses, disable raw
		 * mode so that the program is required to
		 * initialize all the memory that the helper could
		 * just partially fill up.
		 */
		meta = NULL;

	if (reg->smin_value < 0) {
		verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n",
			regno);
		return -EACCES;
	}

	if (reg->umin_value == 0 && !zero_size_allowed) {
		verbose(env, "R%d invalid zero-sized read: u64=[%lld,%lld]\n",
			regno, reg->umin_value, reg->umax_value);
		return -EACCES;
	}

	if (reg->umax_value >= BPF_MAX_VAR_SIZ) {
		verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
			regno);
		return -EACCES;
	}
	err = check_helper_mem_access(env, regno - 1,
				      reg->umax_value,
				      zero_size_allowed, meta);
	if (!err)
		err = mark_chain_precision(env, regno);
	return err;
}

static int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
			 u32 regno, u32 mem_size)
{
	bool may_be_null = type_may_be_null(reg->type);
	struct bpf_reg_state saved_reg;
	struct bpf_call_arg_meta meta;
	int err;

	if (register_is_null(reg))
		return 0;

	memset(&meta, 0, sizeof(meta));
	/* Assuming that the register contains a value check if the memory
	 * access is safe. Temporarily save and restore the register's state as
	 * the conversion shouldn't be visible to a caller.
	 */
	if (may_be_null) {
		saved_reg = *reg;
		mark_ptr_not_null_reg(reg);
	}

	err = check_helper_mem_access(env, regno, mem_size, true, &meta);
	/* Check access for BPF_WRITE */
	meta.raw_mode = true;
	err = err ?: check_helper_mem_access(env, regno, mem_size, true, &meta);

	if (may_be_null)
		*reg = saved_reg;

	return err;
}

static int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
				    u32 regno)
{
	struct bpf_reg_state *mem_reg = &cur_regs(env)[regno - 1];
	bool may_be_null = type_may_be_null(mem_reg->type);
	struct bpf_reg_state saved_reg;
	struct bpf_call_arg_meta meta;
	int err;

	WARN_ON_ONCE(regno < BPF_REG_2 || regno > BPF_REG_5);

	memset(&meta, 0, sizeof(meta));

	if (may_be_null) {
		saved_reg = *mem_reg;
		mark_ptr_not_null_reg(mem_reg);
	}

	err = check_mem_size_reg(env, reg, regno, true, &meta);
	/* Check access for BPF_WRITE */
	meta.raw_mode = true;
	err = err ?: check_mem_size_reg(env, reg, regno, true, &meta);

	if (may_be_null)
		*mem_reg = saved_reg;
	return err;
}

/* Implementation details:
 * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL.
 * bpf_obj_new returns PTR_TO_BTF_ID | MEM_ALLOC | PTR_MAYBE_NULL.
 * Two bpf_map_lookups (even with the same key) will have different reg->id.
 * Two separate bpf_obj_new will also have different reg->id.
 * For traditional PTR_TO_MAP_VALUE or PTR_TO_BTF_ID | MEM_ALLOC, the verifier
 * clears reg->id after value_or_null->value transition, since the verifier only
 * cares about the range of access to valid map value pointer and doesn't care
 * about actual address of the map element.
 * For maps with 'struct bpf_spin_lock' inside map value the verifier keeps
 * reg->id > 0 after value_or_null->value transition. By doing so
 * two bpf_map_lookups will be considered two different pointers that
 * point to different bpf_spin_locks. Likewise for pointers to allocated objects
 * returned from bpf_obj_new.
 * The verifier allows taking only one bpf_spin_lock at a time to avoid
 * dead-locks.
 * Since only one bpf_spin_lock is allowed the checks are simpler than
 * reg_is_refcounted() logic. The verifier needs to remember only
 * one spin_lock instead of array of acquired_refs.
 * cur_state->active_lock remembers which map value element or allocated
 * object got locked and clears it after bpf_spin_unlock.
 */
static int process_spin_lock(struct bpf_verifier_env *env, int regno,
			     bool is_lock)
{
	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
	struct bpf_verifier_state *cur = env->cur_state;
	bool is_const = tnum_is_const(reg->var_off);
	u64 val = reg->var_off.value;
	struct bpf_map *map = NULL;
	struct btf *btf = NULL;
	struct btf_record *rec;

	if (!is_const) {
		verbose(env,
			"R%d doesn't have constant offset. bpf_spin_lock has to be at the constant offset\n",
			regno);
		return -EINVAL;
	}
	if (reg->type == PTR_TO_MAP_VALUE) {
		map = reg->map_ptr;
		if (!map->btf) {
			verbose(env,
				"map '%s' has to have BTF in order to use bpf_spin_lock\n",
				map->name);
			return -EINVAL;
		}
	} else {
		btf = reg->btf;
	}

	rec = reg_btf_record(reg);
	if (!btf_record_has_field(rec, BPF_SPIN_LOCK)) {
		verbose(env, "%s '%s' has no valid bpf_spin_lock\n", map ? "map" : "local",
			map ? map->name : "kptr");
		return -EINVAL;
	}
	if (rec->spin_lock_off != val + reg->off) {
		verbose(env, "off %lld doesn't point to 'struct bpf_spin_lock' that is at %d\n",
			val + reg->off, rec->spin_lock_off);
		return -EINVAL;
	}
	if (is_lock) {
		if (cur->active_lock.ptr) {
			verbose(env,
				"Locking two bpf_spin_locks are not allowed\n");
			return -EINVAL;
		}
		if (map)
			cur->active_lock.ptr = map;
		else
			cur->active_lock.ptr = btf;
		cur->active_lock.id = reg->id;
	} else {
		void *ptr;

		if (map)
			ptr = map;
		else
			ptr = btf;

		if (!cur->active_lock.ptr) {
			verbose(env, "bpf_spin_unlock without taking a lock\n");
			return -EINVAL;
		}
		if (cur->active_lock.ptr != ptr ||
		    cur->active_lock.id != reg->id) {
			verbose(env, "bpf_spin_unlock of different lock\n");
			return -EINVAL;
		}

		invalidate_non_owning_refs(env);

		cur->active_lock.ptr = NULL;
		cur->active_lock.id = 0;
	}
	return 0;
}

static int process_timer_func(struct bpf_verifier_env *env, int regno,
			      struct bpf_call_arg_meta *meta)
{
	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
	bool is_const = tnum_is_const(reg->var_off);
	struct bpf_map *map = reg->map_ptr;
	u64 val = reg->var_off.value;

	if (!is_const) {
		verbose(env,
			"R%d doesn't have constant offset. bpf_timer has to be at the constant offset\n",
			regno);
		return -EINVAL;
	}
	if (!map->btf) {
		verbose(env, "map '%s' has to have BTF in order to use bpf_timer\n",
			map->name);
		return -EINVAL;
	}
	if (!btf_record_has_field(map->record, BPF_TIMER)) {
		verbose(env, "map '%s' has no valid bpf_timer\n", map->name);
		return -EINVAL;
	}
	if (map->record->timer_off != val + reg->off) {
		verbose(env, "off %lld doesn't point to 'struct bpf_timer' that is at %d\n",
			val + reg->off, map->record->timer_off);
		return -EINVAL;
	}
	if (meta->map_ptr) {
		verbose(env, "verifier bug. Two map pointers in a timer helper\n");
		return -EFAULT;
	}
	meta->map_uid = reg->map_uid;
	meta->map_ptr = map;
	return 0;
}

static int process_wq_func(struct bpf_verifier_env *env, int regno,
			   struct bpf_kfunc_call_arg_meta *meta)
{
	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
	struct bpf_map *map = reg->map_ptr;
	u64 val = reg->var_off.value;

	if (map->record->wq_off != val + reg->off) {
		verbose(env, "off %lld doesn't point to 'struct bpf_wq' that is at %d\n",
			val + reg->off, map->record->wq_off);
		return -EINVAL;
	}
	meta->map.uid = reg->map_uid;
	meta->map.ptr = map;
	return 0;
}

static int process_kptr_func(struct bpf_verifier_env *env, int regno,
			     struct bpf_call_arg_meta *meta)
{
	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
	struct btf_field *kptr_field;
	struct bpf_map *map_ptr;
	struct btf_record *rec;
	u32 kptr_off;

	if (type_is_ptr_alloc_obj(reg->type)) {
		rec = reg_btf_record(reg);
	} else { /* PTR_TO_MAP_VALUE */
		map_ptr = reg->map_ptr;
		if (!map_ptr->btf) {
			verbose(env, "map '%s' has to have BTF in order to use bpf_kptr_xchg\n",
				map_ptr->name);
			return -EINVAL;
		}
		rec = map_ptr->record;
		meta->map_ptr = map_ptr;
	}

	if (!tnum_is_const(reg->var_off)) {
		verbose(env,
			"R%d doesn't have constant offset. kptr has to be at the constant offset\n",
			regno);
		return -EINVAL;
	}

	if (!btf_record_has_field(rec, BPF_KPTR)) {
		verbose(env, "R%d has no valid kptr\n", regno);
		return -EINVAL;
	}

	kptr_off = reg->off + reg->var_off.value;
	kptr_field = btf_record_find(rec, kptr_off, BPF_KPTR);
	if (!kptr_field) {
		verbose(env, "off=%d doesn't point to kptr\n", kptr_off);
		return -EACCES;
	}
	if (kptr_field->type != BPF_KPTR_REF && kptr_field->type != BPF_KPTR_PERCPU) {
		verbose(env, "off=%d kptr isn't referenced kptr\n", kptr_off);
		return -EACCES;
	}
	meta->kptr_field = kptr_field;
	return 0;
}

/* There are two register types representing a bpf_dynptr, one is PTR_TO_STACK
 * which points to a stack slot, and the other is CONST_PTR_TO_DYNPTR.
 *
 * In both cases we deal with the first 8 bytes, but need to mark the next 8
 * bytes as STACK_DYNPTR in case of PTR_TO_STACK. In case of
 * CONST_PTR_TO_DYNPTR, we are guaranteed to get the beginning of the object.
 *
 * Mutability of bpf_dynptr is at two levels, one is at the level of struct
 * bpf_dynptr itself, i.e. whether the helper is receiving a pointer to struct
 * bpf_dynptr or pointer to const struct bpf_dynptr. In the former case, it can
 * mutate the view of the dynptr and also possibly destroy it. In the latter
 * case, it cannot mutate the bpf_dynptr itself but it can still mutate the
 * memory that dynptr points to.
 *
 * The verifier will keep track both levels of mutation (bpf_dynptr's in
 * reg->type and the memory's in reg->dynptr.type), but there is no support for
 * readonly dynptr view yet, hence only the first case is tracked and checked.
 *
 * This is consistent with how C applies the const modifier to a struct object,
 * where the pointer itself inside bpf_dynptr becomes const but not what it
 * points to.
 *
 * Helpers which do not mutate the bpf_dynptr set MEM_RDONLY in their argument
 * type, and declare it as 'const struct bpf_dynptr *' in their prototype.
 */
static int process_dynptr_func(struct bpf_verifier_env *env, int regno, int insn_idx,
			       enum bpf_arg_type arg_type, int clone_ref_obj_id)
{
	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
	int err;

	if (reg->type != PTR_TO_STACK && reg->type != CONST_PTR_TO_DYNPTR) {
		verbose(env,
			"arg#%d expected pointer to stack or const struct bpf_dynptr\n",
			regno);
		return -EINVAL;
	}

	/* MEM_UNINIT and MEM_RDONLY are exclusive, when applied to an
	 * ARG_PTR_TO_DYNPTR (or ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_*):
	 */
	if ((arg_type & (MEM_UNINIT | MEM_RDONLY)) == (MEM_UNINIT | MEM_RDONLY)) {
		verbose(env, "verifier internal error: misconfigured dynptr helper type flags\n");
		return -EFAULT;
	}

	/*  MEM_UNINIT - Points to memory that is an appropriate candidate for
	 *		 constructing a mutable bpf_dynptr object.
	 *
	 *		 Currently, this is only possible with PTR_TO_STACK
	 *		 pointing to a region of at least 16 bytes which doesn't
	 *		 contain an existing bpf_dynptr.
	 *
	 *  MEM_RDONLY - Points to a initialized bpf_dynptr that will not be
	 *		 mutated or destroyed. However, the memory it points to
	 *		 may be mutated.
	 *
	 *  None       - Points to a initialized dynptr that can be mutated and
	 *		 destroyed, including mutation of the memory it points
	 *		 to.
	 */
	if (arg_type & MEM_UNINIT) {
		int i;

		if (!is_dynptr_reg_valid_uninit(env, reg)) {
			verbose(env, "Dynptr has to be an uninitialized dynptr\n");
			return -EINVAL;
		}

		/* we write BPF_DW bits (8 bytes) at a time */
		for (i = 0; i < BPF_DYNPTR_SIZE; i += 8) {
			err = check_mem_access(env, insn_idx, regno,
					       i, BPF_DW, BPF_WRITE, -1, false, false);
			if (err)
				return err;
		}

		err = mark_stack_slots_dynptr(env, reg, arg_type, insn_idx, clone_ref_obj_id);
	} else /* MEM_RDONLY and None case from above */ {
		/* For the reg->type == PTR_TO_STACK case, bpf_dynptr is never const */
		if (reg->type == CONST_PTR_TO_DYNPTR && !(arg_type & MEM_RDONLY)) {
			verbose(env, "cannot pass pointer to const bpf_dynptr, the helper mutates it\n");
			return -EINVAL;
		}

		if (!is_dynptr_reg_valid_init(env, reg)) {
			verbose(env,
				"Expected an initialized dynptr as arg #%d\n",
				regno);
			return -EINVAL;
		}

		/* Fold modifiers (in this case, MEM_RDONLY) when checking expected type */
		if (!is_dynptr_type_expected(env, reg, arg_type & ~MEM_RDONLY)) {
			verbose(env,
				"Expected a dynptr of type %s as arg #%d\n",
				dynptr_type_str(arg_to_dynptr_type(arg_type)), regno);
			return -EINVAL;
		}

		err = mark_dynptr_read(env, reg);
	}
	return err;
}

static u32 iter_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg, int spi)
{
	struct bpf_func_state *state = func(env, reg);

	return state->stack[spi].spilled_ptr.ref_obj_id;
}

static bool is_iter_kfunc(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->kfunc_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY);
}

static bool is_iter_new_kfunc(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->kfunc_flags & KF_ITER_NEW;
}

static bool is_iter_next_kfunc(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->kfunc_flags & KF_ITER_NEXT;
}

static bool is_iter_destroy_kfunc(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->kfunc_flags & KF_ITER_DESTROY;
}

static bool is_kfunc_arg_iter(struct bpf_kfunc_call_arg_meta *meta, int arg_idx,
			      const struct btf_param *arg)
{
	/* btf_check_iter_kfuncs() guarantees that first argument of any iter
	 * kfunc is iter state pointer
	 */
	if (is_iter_kfunc(meta))
		return arg_idx == 0;

	/* iter passed as an argument to a generic kfunc */
	return btf_param_match_suffix(meta->btf, arg, "__iter");
}

static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_idx,
			    struct bpf_kfunc_call_arg_meta *meta)
{
	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
	const struct btf_type *t;
	int spi, err, i, nr_slots, btf_id;

	/* For iter_{new,next,destroy} functions, btf_check_iter_kfuncs()
	 * ensures struct convention, so we wouldn't need to do any BTF
	 * validation here. But given iter state can be passed as a parameter
	 * to any kfunc, if arg has "__iter" suffix, we need to be a bit more
	 * conservative here.
	 */
	btf_id = btf_check_iter_arg(meta->btf, meta->func_proto, regno - 1);
	if (btf_id < 0) {
		verbose(env, "expected valid iter pointer as arg #%d\n", regno);
		return -EINVAL;
	}
	t = btf_type_by_id(meta->btf, btf_id);
	nr_slots = t->size / BPF_REG_SIZE;

	if (is_iter_new_kfunc(meta)) {
		/* bpf_iter_<type>_new() expects pointer to uninit iter state */
		if (!is_iter_reg_valid_uninit(env, reg, nr_slots)) {
			verbose(env, "expected uninitialized iter_%s as arg #%d\n",
				iter_type_str(meta->btf, btf_id), regno);
			return -EINVAL;
		}

		for (i = 0; i < nr_slots * 8; i += BPF_REG_SIZE) {
			err = check_mem_access(env, insn_idx, regno,
					       i, BPF_DW, BPF_WRITE, -1, false, false);
			if (err)
				return err;
		}

		err = mark_stack_slots_iter(env, meta, reg, insn_idx, meta->btf, btf_id, nr_slots);
		if (err)
			return err;
	} else {
		/* iter_next() or iter_destroy(), as well as any kfunc
		 * accepting iter argument, expect initialized iter state
		 */
		err = is_iter_reg_valid_init(env, reg, meta->btf, btf_id, nr_slots);
		switch (err) {
		case 0:
			break;
		case -EINVAL:
			verbose(env, "expected an initialized iter_%s as arg #%d\n",
				iter_type_str(meta->btf, btf_id), regno);
			return err;
		case -EPROTO:
			verbose(env, "expected an RCU CS when using %s\n", meta->func_name);
			return err;
		default:
			return err;
		}

		spi = iter_get_spi(env, reg, nr_slots);
		if (spi < 0)
			return spi;

		err = mark_iter_read(env, reg, spi, nr_slots);
		if (err)
			return err;

		/* remember meta->iter info for process_iter_next_call() */
		meta->iter.spi = spi;
		meta->iter.frameno = reg->frameno;
		meta->ref_obj_id = iter_ref_obj_id(env, reg, spi);

		if (is_iter_destroy_kfunc(meta)) {
			err = unmark_stack_slots_iter(env, reg, nr_slots);
			if (err)
				return err;
		}
	}

	return 0;
}

/* Look for a previous loop entry at insn_idx: nearest parent state
 * stopped at insn_idx with callsites matching those in cur->frame.
 */
static struct bpf_verifier_state *find_prev_entry(struct bpf_verifier_env *env,
						  struct bpf_verifier_state *cur,
						  int insn_idx)
{
	struct bpf_verifier_state_list *sl;
	struct bpf_verifier_state *st;

	/* Explored states are pushed in stack order, most recent states come first */
	sl = *explored_state(env, insn_idx);
	for (; sl; sl = sl->next) {
		/* If st->branches != 0 state is a part of current DFS verification path,
		 * hence cur & st for a loop.
		 */
		st = &sl->state;
		if (st->insn_idx == insn_idx && st->branches && same_callsites(st, cur) &&
		    st->dfs_depth < cur->dfs_depth)
			return st;
	}

	return NULL;
}

static void reset_idmap_scratch(struct bpf_verifier_env *env);
static bool regs_exact(const struct bpf_reg_state *rold,
		       const struct bpf_reg_state *rcur,
		       struct bpf_idmap *idmap);

static void maybe_widen_reg(struct bpf_verifier_env *env,
			    struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
			    struct bpf_idmap *idmap)
{
	if (rold->type != SCALAR_VALUE)
		return;
	if (rold->type != rcur->type)
		return;
	if (rold->precise || rcur->precise || regs_exact(rold, rcur, idmap))
		return;
	__mark_reg_unknown(env, rcur);
}

static int widen_imprecise_scalars(struct bpf_verifier_env *env,
				   struct bpf_verifier_state *old,
				   struct bpf_verifier_state *cur)
{
	struct bpf_func_state *fold, *fcur;
	int i, fr;

	reset_idmap_scratch(env);
	for (fr = old->curframe; fr >= 0; fr--) {
		fold = old->frame[fr];
		fcur = cur->frame[fr];

		for (i = 0; i < MAX_BPF_REG; i++)
			maybe_widen_reg(env,
					&fold->regs[i],
					&fcur->regs[i],
					&env->idmap_scratch);

		for (i = 0; i < fold->allocated_stack / BPF_REG_SIZE; i++) {
			if (!is_spilled_reg(&fold->stack[i]) ||
			    !is_spilled_reg(&fcur->stack[i]))
				continue;

			maybe_widen_reg(env,
					&fold->stack[i].spilled_ptr,
					&fcur->stack[i].spilled_ptr,
					&env->idmap_scratch);
		}
	}
	return 0;
}

static struct bpf_reg_state *get_iter_from_state(struct bpf_verifier_state *cur_st,
						 struct bpf_kfunc_call_arg_meta *meta)
{
	int iter_frameno = meta->iter.frameno;
	int iter_spi = meta->iter.spi;

	return &cur_st->frame[iter_frameno]->stack[iter_spi].spilled_ptr;
}

/* process_iter_next_call() is called when verifier gets to iterator's next
 * "method" (e.g., bpf_iter_num_next() for numbers iterator) call. We'll refer
 * to it as just "iter_next()" in comments below.
 *
 * BPF verifier relies on a crucial contract for any iter_next()
 * implementation: it should *eventually* return NULL, and once that happens
 * it should keep returning NULL. That is, once iterator exhausts elements to
 * iterate, it should never reset or spuriously return new elements.
 *
 * With the assumption of such contract, process_iter_next_call() simulates
 * a fork in the verifier state to validate loop logic correctness and safety
 * without having to simulate infinite amount of iterations.
 *
 * In current state, we first assume that iter_next() returned NULL and
 * iterator state is set to DRAINED (BPF_ITER_STATE_DRAINED). In such
 * conditions we should not form an infinite loop and should eventually reach
 * exit.
 *
 * Besides that, we also fork current state and enqueue it for later
 * verification. In a forked state we keep iterator state as ACTIVE
 * (BPF_ITER_STATE_ACTIVE) and assume non-NULL return from iter_next(). We
 * also bump iteration depth to prevent erroneous infinite loop detection
 * later on (see iter_active_depths_differ() comment for details). In this
 * state we assume that we'll eventually loop back to another iter_next()
 * calls (it could be in exactly same location or in some other instruction,
 * it doesn't matter, we don't make any unnecessary assumptions about this,
 * everything revolves around iterator state in a stack slot, not which
 * instruction is calling iter_next()). When that happens, we either will come
 * to iter_next() with equivalent state and can conclude that next iteration
 * will proceed in exactly the same way as we just verified, so it's safe to
 * assume that loop converges. If not, we'll go on another iteration
 * simulation with a different input state, until all possible starting states
 * are validated or we reach maximum number of instructions limit.
 *
 * This way, we will either exhaustively discover all possible input states
 * that iterator loop can start with and eventually will converge, or we'll
 * effectively regress into bounded loop simulation logic and either reach
 * maximum number of instructions if loop is not provably convergent, or there
 * is some statically known limit on number of iterations (e.g., if there is
 * an explicit `if n > 100 then break;` statement somewhere in the loop).
 *
 * Iteration convergence logic in is_state_visited() relies on exact
 * states comparison, which ignores read and precision marks.
 * This is necessary because read and precision marks are not finalized
 * while in the loop. Exact comparison might preclude convergence for
 * simple programs like below:
 *
 *     i = 0;
 *     while(iter_next(&it))
 *       i++;
 *
 * At each iteration step i++ would produce a new distinct state and
 * eventually instruction processing limit would be reached.
 *
 * To avoid such behavior speculatively forget (widen) range for
 * imprecise scalar registers, if those registers were not precise at the
 * end of the previous iteration and do not match exactly.
 *
 * This is a conservative heuristic that allows to verify wide range of programs,
 * however it precludes verification of programs that conjure an
 * imprecise value on the first loop iteration and use it as precise on a second.
 * For example, the following safe program would fail to verify:
 *
 *     struct bpf_num_iter it;
 *     int arr[10];
 *     int i = 0, a = 0;
 *     bpf_iter_num_new(&it, 0, 10);
 *     while (bpf_iter_num_next(&it)) {
 *       if (a == 0) {
 *         a = 1;
 *         i = 7; // Because i changed verifier would forget
 *                // it's range on second loop entry.
 *       } else {
 *         arr[i] = 42; // This would fail to verify.
 *       }
 *     }
 *     bpf_iter_num_destroy(&it);
 */
static int process_iter_next_call(struct bpf_verifier_env *env, int insn_idx,
				  struct bpf_kfunc_call_arg_meta *meta)
{
	struct bpf_verifier_state *cur_st = env->cur_state, *queued_st, *prev_st;
	struct bpf_func_state *cur_fr = cur_st->frame[cur_st->curframe], *queued_fr;
	struct bpf_reg_state *cur_iter, *queued_iter;

	BTF_TYPE_EMIT(struct bpf_iter);

	cur_iter = get_iter_from_state(cur_st, meta);

	if (cur_iter->iter.state != BPF_ITER_STATE_ACTIVE &&
	    cur_iter->iter.state != BPF_ITER_STATE_DRAINED) {
		verbose(env, "verifier internal error: unexpected iterator state %d (%s)\n",
			cur_iter->iter.state, iter_state_str(cur_iter->iter.state));
		return -EFAULT;
	}

	if (cur_iter->iter.state == BPF_ITER_STATE_ACTIVE) {
		/* Because iter_next() call is a checkpoint is_state_visitied()
		 * should guarantee parent state with same call sites and insn_idx.
		 */
		if (!cur_st->parent || cur_st->parent->insn_idx != insn_idx ||
		    !same_callsites(cur_st->parent, cur_st)) {
			verbose(env, "bug: bad parent state for iter next call");
			return -EFAULT;
		}
		/* Note cur_st->parent in the call below, it is necessary to skip
		 * checkpoint created for cur_st by is_state_visited()
		 * right at this instruction.
		 */
		prev_st = find_prev_entry(env, cur_st->parent, insn_idx);
		/* branch out active iter state */
		queued_st = push_stack(env, insn_idx + 1, insn_idx, false);
		if (!queued_st)
			return -ENOMEM;

		queued_iter = get_iter_from_state(queued_st, meta);
		queued_iter->iter.state = BPF_ITER_STATE_ACTIVE;
		queued_iter->iter.depth++;
		if (prev_st)
			widen_imprecise_scalars(env, prev_st, queued_st);

		queued_fr = queued_st->frame[queued_st->curframe];
		mark_ptr_not_null_reg(&queued_fr->regs[BPF_REG_0]);
	}

	/* switch to DRAINED state, but keep the depth unchanged */
	/* mark current iter state as drained and assume returned NULL */
	cur_iter->iter.state = BPF_ITER_STATE_DRAINED;
	__mark_reg_const_zero(env, &cur_fr->regs[BPF_REG_0]);

	return 0;
}

static bool arg_type_is_mem_size(enum bpf_arg_type type)
{
	return type == ARG_CONST_SIZE ||
	       type == ARG_CONST_SIZE_OR_ZERO;
}

static bool arg_type_is_raw_mem(enum bpf_arg_type type)
{
	return base_type(type) == ARG_PTR_TO_MEM &&
	       type & MEM_UNINIT;
}

static bool arg_type_is_release(enum bpf_arg_type type)
{
	return type & OBJ_RELEASE;
}

static bool arg_type_is_dynptr(enum bpf_arg_type type)
{
	return base_type(type) == ARG_PTR_TO_DYNPTR;
}

static int resolve_map_arg_type(struct bpf_verifier_env *env,
				 const struct bpf_call_arg_meta *meta,
				 enum bpf_arg_type *arg_type)
{
	if (!meta->map_ptr) {
		/* kernel subsystem misconfigured verifier */
		verbose(env, "invalid map_ptr to access map->type\n");
		return -EACCES;
	}

	switch (meta->map_ptr->map_type) {
	case BPF_MAP_TYPE_SOCKMAP:
	case BPF_MAP_TYPE_SOCKHASH:
		if (*arg_type == ARG_PTR_TO_MAP_VALUE) {
			*arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON;
		} else {
			verbose(env, "invalid arg_type for sockmap/sockhash\n");
			return -EINVAL;
		}
		break;
	case BPF_MAP_TYPE_BLOOM_FILTER:
		if (meta->func_id == BPF_FUNC_map_peek_elem)
			*arg_type = ARG_PTR_TO_MAP_VALUE;
		break;
	default:
		break;
	}
	return 0;
}

struct bpf_reg_types {
	const enum bpf_reg_type types[10];
	u32 *btf_id;
};

static const struct bpf_reg_types sock_types = {
	.types = {
		PTR_TO_SOCK_COMMON,
		PTR_TO_SOCKET,
		PTR_TO_TCP_SOCK,
		PTR_TO_XDP_SOCK,
	},
};

#ifdef CONFIG_NET
static const struct bpf_reg_types btf_id_sock_common_types = {
	.types = {
		PTR_TO_SOCK_COMMON,
		PTR_TO_SOCKET,
		PTR_TO_TCP_SOCK,
		PTR_TO_XDP_SOCK,
		PTR_TO_BTF_ID,
		PTR_TO_BTF_ID | PTR_TRUSTED,
	},
	.btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
};
#endif

static const struct bpf_reg_types mem_types = {
	.types = {
		PTR_TO_STACK,
		PTR_TO_PACKET,
		PTR_TO_PACKET_META,
		PTR_TO_MAP_KEY,
		PTR_TO_MAP_VALUE,
		PTR_TO_MEM,
		PTR_TO_MEM | MEM_RINGBUF,
		PTR_TO_BUF,
		PTR_TO_BTF_ID | PTR_TRUSTED,
	},
};

static const struct bpf_reg_types spin_lock_types = {
	.types = {
		PTR_TO_MAP_VALUE,
		PTR_TO_BTF_ID | MEM_ALLOC,
	}
};

static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } };
static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } };
static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } };
static const struct bpf_reg_types ringbuf_mem_types = { .types = { PTR_TO_MEM | MEM_RINGBUF } };
static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } };
static const struct bpf_reg_types btf_ptr_types = {
	.types = {
		PTR_TO_BTF_ID,
		PTR_TO_BTF_ID | PTR_TRUSTED,
		PTR_TO_BTF_ID | MEM_RCU,
	},
};
static const struct bpf_reg_types percpu_btf_ptr_types = {
	.types = {
		PTR_TO_BTF_ID | MEM_PERCPU,
		PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU,
		PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED,
	}
};
static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } };
static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } };
static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } };
static const struct bpf_reg_types timer_types = { .types = { PTR_TO_MAP_VALUE } };
static const struct bpf_reg_types kptr_xchg_dest_types = {
	.types = {
		PTR_TO_MAP_VALUE,
		PTR_TO_BTF_ID | MEM_ALLOC
	}
};
static const struct bpf_reg_types dynptr_types = {
	.types = {
		PTR_TO_STACK,
		CONST_PTR_TO_DYNPTR,
	}
};

static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
	[ARG_PTR_TO_MAP_KEY]		= &mem_types,
	[ARG_PTR_TO_MAP_VALUE]		= &mem_types,
	[ARG_CONST_SIZE]		= &scalar_types,
	[ARG_CONST_SIZE_OR_ZERO]	= &scalar_types,
	[ARG_CONST_ALLOC_SIZE_OR_ZERO]	= &scalar_types,
	[ARG_CONST_MAP_PTR]		= &const_map_ptr_types,
	[ARG_PTR_TO_CTX]		= &context_types,
	[ARG_PTR_TO_SOCK_COMMON]	= &sock_types,
#ifdef CONFIG_NET
	[ARG_PTR_TO_BTF_ID_SOCK_COMMON]	= &btf_id_sock_common_types,
#endif
	[ARG_PTR_TO_SOCKET]		= &fullsock_types,
	[ARG_PTR_TO_BTF_ID]		= &btf_ptr_types,
	[ARG_PTR_TO_SPIN_LOCK]		= &spin_lock_types,
	[ARG_PTR_TO_MEM]		= &mem_types,
	[ARG_PTR_TO_RINGBUF_MEM]	= &ringbuf_mem_types,
	[ARG_PTR_TO_PERCPU_BTF_ID]	= &percpu_btf_ptr_types,
	[ARG_PTR_TO_FUNC]		= &func_ptr_types,
	[ARG_PTR_TO_STACK]		= &stack_ptr_types,
	[ARG_PTR_TO_CONST_STR]		= &const_str_ptr_types,
	[ARG_PTR_TO_TIMER]		= &timer_types,
	[ARG_KPTR_XCHG_DEST]		= &kptr_xchg_dest_types,
	[ARG_PTR_TO_DYNPTR]		= &dynptr_types,
};

static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
			  enum bpf_arg_type arg_type,
			  const u32 *arg_btf_id,
			  struct bpf_call_arg_meta *meta)
{
	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
	enum bpf_reg_type expected, type = reg->type;
	const struct bpf_reg_types *compatible;
	int i, j;

	compatible = compatible_reg_types[base_type(arg_type)];
	if (!compatible) {
		verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type);
		return -EFAULT;
	}

	/* ARG_PTR_TO_MEM + RDONLY is compatible with PTR_TO_MEM and PTR_TO_MEM + RDONLY,
	 * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM and NOT with PTR_TO_MEM + RDONLY
	 *
	 * Same for MAYBE_NULL:
	 *
	 * ARG_PTR_TO_MEM + MAYBE_NULL is compatible with PTR_TO_MEM and PTR_TO_MEM + MAYBE_NULL,
	 * but ARG_PTR_TO_MEM is compatible only with PTR_TO_MEM but NOT with PTR_TO_MEM + MAYBE_NULL
	 *
	 * ARG_PTR_TO_MEM is compatible with PTR_TO_MEM that is tagged with a dynptr type.
	 *
	 * Therefore we fold these flags depending on the arg_type before comparison.
	 */
	if (arg_type & MEM_RDONLY)
		type &= ~MEM_RDONLY;
	if (arg_type & PTR_MAYBE_NULL)
		type &= ~PTR_MAYBE_NULL;
	if (base_type(arg_type) == ARG_PTR_TO_MEM)
		type &= ~DYNPTR_TYPE_FLAG_MASK;

	/* Local kptr types are allowed as the source argument of bpf_kptr_xchg */
	if (meta->func_id == BPF_FUNC_kptr_xchg && type_is_alloc(type) && regno == BPF_REG_2) {
		type &= ~MEM_ALLOC;
		type &= ~MEM_PERCPU;
	}

	for (i = 0; i < ARRAY_SIZE(compatible->types); i++) {
		expected = compatible->types[i];
		if (expected == NOT_INIT)
			break;

		if (type == expected)
			goto found;
	}

	verbose(env, "R%d type=%s expected=", regno, reg_type_str(env, reg->type));
	for (j = 0; j + 1 < i; j++)
		verbose(env, "%s, ", reg_type_str(env, compatible->types[j]));
	verbose(env, "%s\n", reg_type_str(env, compatible->types[j]));
	return -EACCES;

found:
	if (base_type(reg->type) != PTR_TO_BTF_ID)
		return 0;

	if (compatible == &mem_types) {
		if (!(arg_type & MEM_RDONLY)) {
			verbose(env,
				"%s() may write into memory pointed by R%d type=%s\n",
				func_id_name(meta->func_id),
				regno, reg_type_str(env, reg->type));
			return -EACCES;
		}
		return 0;
	}

	switch ((int)reg->type) {
	case PTR_TO_BTF_ID:
	case PTR_TO_BTF_ID | PTR_TRUSTED:
	case PTR_TO_BTF_ID | PTR_TRUSTED | PTR_MAYBE_NULL:
	case PTR_TO_BTF_ID | MEM_RCU:
	case PTR_TO_BTF_ID | PTR_MAYBE_NULL:
	case PTR_TO_BTF_ID | PTR_MAYBE_NULL | MEM_RCU:
	{
		/* For bpf_sk_release, it needs to match against first member
		 * 'struct sock_common', hence make an exception for it. This
		 * allows bpf_sk_release to work for multiple socket types.
		 */
		bool strict_type_match = arg_type_is_release(arg_type) &&
					 meta->func_id != BPF_FUNC_sk_release;

		if (type_may_be_null(reg->type) &&
		    (!type_may_be_null(arg_type) || arg_type_is_release(arg_type))) {
			verbose(env, "Possibly NULL pointer passed to helper arg%d\n", regno);
			return -EACCES;
		}

		if (!arg_btf_id) {
			if (!compatible->btf_id) {
				verbose(env, "verifier internal error: missing arg compatible BTF ID\n");
				return -EFAULT;
			}
			arg_btf_id = compatible->btf_id;
		}

		if (meta->func_id == BPF_FUNC_kptr_xchg) {
			if (map_kptr_match_type(env, meta->kptr_field, reg, regno))
				return -EACCES;
		} else {
			if (arg_btf_id == BPF_PTR_POISON) {
				verbose(env, "verifier internal error:");
				verbose(env, "R%d has non-overwritten BPF_PTR_POISON type\n",
					regno);
				return -EACCES;
			}

			if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, reg->off,
						  btf_vmlinux, *arg_btf_id,
						  strict_type_match)) {
				verbose(env, "R%d is of type %s but %s is expected\n",
					regno, btf_type_name(reg->btf, reg->btf_id),
					btf_type_name(btf_vmlinux, *arg_btf_id));
				return -EACCES;
			}
		}
		break;
	}
	case PTR_TO_BTF_ID | MEM_ALLOC:
	case PTR_TO_BTF_ID | MEM_PERCPU | MEM_ALLOC:
		if (meta->func_id != BPF_FUNC_spin_lock && meta->func_id != BPF_FUNC_spin_unlock &&
		    meta->func_id != BPF_FUNC_kptr_xchg) {
			verbose(env, "verifier internal error: unimplemented handling of MEM_ALLOC\n");
			return -EFAULT;
		}
		/* Check if local kptr in src arg matches kptr in dst arg */
		if (meta->func_id == BPF_FUNC_kptr_xchg && regno == BPF_REG_2) {
			if (map_kptr_match_type(env, meta->kptr_field, reg, regno))
				return -EACCES;
		}
		break;
	case PTR_TO_BTF_ID | MEM_PERCPU:
	case PTR_TO_BTF_ID | MEM_PERCPU | MEM_RCU:
	case PTR_TO_BTF_ID | MEM_PERCPU | PTR_TRUSTED:
		/* Handled by helper specific checks */
		break;
	default:
		verbose(env, "verifier internal error: invalid PTR_TO_BTF_ID register for type match\n");
		return -EFAULT;
	}
	return 0;
}

static struct btf_field *
reg_find_field_offset(const struct bpf_reg_state *reg, s32 off, u32 fields)
{
	struct btf_field *field;
	struct btf_record *rec;

	rec = reg_btf_record(reg);
	if (!rec)
		return NULL;

	field = btf_record_find(rec, off, fields);
	if (!field)
		return NULL;

	return field;
}

static int check_func_arg_reg_off(struct bpf_verifier_env *env,
				  const struct bpf_reg_state *reg, int regno,
				  enum bpf_arg_type arg_type)
{
	u32 type = reg->type;

	/* When referenced register is passed to release function, its fixed
	 * offset must be 0.
	 *
	 * We will check arg_type_is_release reg has ref_obj_id when storing
	 * meta->release_regno.
	 */
	if (arg_type_is_release(arg_type)) {
		/* ARG_PTR_TO_DYNPTR with OBJ_RELEASE is a bit special, as it
		 * may not directly point to the object being released, but to
		 * dynptr pointing to such object, which might be at some offset
		 * on the stack. In that case, we simply to fallback to the
		 * default handling.
		 */
		if (arg_type_is_dynptr(arg_type) && type == PTR_TO_STACK)
			return 0;

		/* Doing check_ptr_off_reg check for the offset will catch this
		 * because fixed_off_ok is false, but checking here allows us
		 * to give the user a better error message.
		 */
		if (reg->off) {
			verbose(env, "R%d must have zero offset when passed to release func or trusted arg to kfunc\n",
				regno);
			return -EINVAL;
		}
		return __check_ptr_off_reg(env, reg, regno, false);
	}

	switch (type) {
	/* Pointer types where both fixed and variable offset is explicitly allowed: */
	case PTR_TO_STACK:
	case PTR_TO_PACKET:
	case PTR_TO_PACKET_META:
	case PTR_TO_MAP_KEY:
	case PTR_TO_MAP_VALUE:
	case PTR_TO_MEM:
	case PTR_TO_MEM | MEM_RDONLY:
	case PTR_TO_MEM | MEM_RINGBUF:
	case PTR_TO_BUF:
	case PTR_TO_BUF | MEM_RDONLY:
	case PTR_TO_ARENA:
	case SCALAR_VALUE:
		return 0;
	/* All the rest must be rejected, except PTR_TO_BTF_ID which allows
	 * fixed offset.
	 */
	case PTR_TO_BTF_ID:
	case PTR_TO_BTF_ID | MEM_ALLOC:
	case PTR_TO_BTF_ID | PTR_TRUSTED:
	case PTR_TO_BTF_ID | MEM_RCU:
	case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF:
	case PTR_TO_BTF_ID | MEM_ALLOC | NON_OWN_REF | MEM_RCU:
		/* When referenced PTR_TO_BTF_ID is passed to release function,
		 * its fixed offset must be 0. In the other cases, fixed offset
		 * can be non-zero. This was already checked above. So pass
		 * fixed_off_ok as true to allow fixed offset for all other
		 * cases. var_off always must be 0 for PTR_TO_BTF_ID, hence we
		 * still need to do checks instead of returning.
		 */
		return __check_ptr_off_reg(env, reg, regno, true);
	default:
		return __check_ptr_off_reg(env, reg, regno, false);
	}
}

static struct bpf_reg_state *get_dynptr_arg_reg(struct bpf_verifier_env *env,
						const struct bpf_func_proto *fn,
						struct bpf_reg_state *regs)
{
	struct bpf_reg_state *state = NULL;
	int i;

	for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++)
		if (arg_type_is_dynptr(fn->arg_type[i])) {
			if (state) {
				verbose(env, "verifier internal error: multiple dynptr args\n");
				return NULL;
			}
			state = &regs[BPF_REG_1 + i];
		}

	if (!state)
		verbose(env, "verifier internal error: no dynptr arg found\n");

	return state;
}

static int dynptr_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
	struct bpf_func_state *state = func(env, reg);
	int spi;

	if (reg->type == CONST_PTR_TO_DYNPTR)
		return reg->id;
	spi = dynptr_get_spi(env, reg);
	if (spi < 0)
		return spi;
	return state->stack[spi].spilled_ptr.id;
}

static int dynptr_ref_obj_id(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
	struct bpf_func_state *state = func(env, reg);
	int spi;

	if (reg->type == CONST_PTR_TO_DYNPTR)
		return reg->ref_obj_id;
	spi = dynptr_get_spi(env, reg);
	if (spi < 0)
		return spi;
	return state->stack[spi].spilled_ptr.ref_obj_id;
}

static enum bpf_dynptr_type dynptr_get_type(struct bpf_verifier_env *env,
					    struct bpf_reg_state *reg)
{
	struct bpf_func_state *state = func(env, reg);
	int spi;

	if (reg->type == CONST_PTR_TO_DYNPTR)
		return reg->dynptr.type;

	spi = __get_spi(reg->off);
	if (spi < 0) {
		verbose(env, "verifier internal error: invalid spi when querying dynptr type\n");
		return BPF_DYNPTR_TYPE_INVALID;
	}

	return state->stack[spi].spilled_ptr.dynptr.type;
}

static int check_reg_const_str(struct bpf_verifier_env *env,
			       struct bpf_reg_state *reg, u32 regno)
{
	struct bpf_map *map = reg->map_ptr;
	int err;
	int map_off;
	u64 map_addr;
	char *str_ptr;

	if (reg->type != PTR_TO_MAP_VALUE)
		return -EINVAL;

	if (!bpf_map_is_rdonly(map)) {
		verbose(env, "R%d does not point to a readonly map'\n", regno);
		return -EACCES;
	}

	if (!tnum_is_const(reg->var_off)) {
		verbose(env, "R%d is not a constant address'\n", regno);
		return -EACCES;
	}

	if (!map->ops->map_direct_value_addr) {
		verbose(env, "no direct value access support for this map type\n");
		return -EACCES;
	}

	err = check_map_access(env, regno, reg->off,
			       map->value_size - reg->off, false,
			       ACCESS_HELPER);
	if (err)
		return err;

	map_off = reg->off + reg->var_off.value;
	err = map->ops->map_direct_value_addr(map, &map_addr, map_off);
	if (err) {
		verbose(env, "direct value access on string failed\n");
		return err;
	}

	str_ptr = (char *)(long)(map_addr);
	if (!strnchr(str_ptr + map_off, map->value_size - map_off, 0)) {
		verbose(env, "string is not zero-terminated\n");
		return -EINVAL;
	}
	return 0;
}

static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
			  struct bpf_call_arg_meta *meta,
			  const struct bpf_func_proto *fn,
			  int insn_idx)
{
	u32 regno = BPF_REG_1 + arg;
	struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
	enum bpf_arg_type arg_type = fn->arg_type[arg];
	enum bpf_reg_type type = reg->type;
	u32 *arg_btf_id = NULL;
	int err = 0;

	if (arg_type == ARG_DONTCARE)
		return 0;

	err = check_reg_arg(env, regno, SRC_OP);
	if (err)
		return err;

	if (arg_type == ARG_ANYTHING) {
		if (is_pointer_value(env, regno)) {
			verbose(env, "R%d leaks addr into helper function\n",
				regno);
			return -EACCES;
		}
		return 0;
	}

	if (type_is_pkt_pointer(type) &&
	    !may_access_direct_pkt_data(env, meta, BPF_READ)) {
		verbose(env, "helper access to the packet is not allowed\n");
		return -EACCES;
	}

	if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE) {
		err = resolve_map_arg_type(env, meta, &arg_type);
		if (err)
			return err;
	}

	if (register_is_null(reg) && type_may_be_null(arg_type))
		/* A NULL register has a SCALAR_VALUE type, so skip
		 * type checking.
		 */
		goto skip_type_check;

	/* arg_btf_id and arg_size are in a union. */
	if (base_type(arg_type) == ARG_PTR_TO_BTF_ID ||
	    base_type(arg_type) == ARG_PTR_TO_SPIN_LOCK)
		arg_btf_id = fn->arg_btf_id[arg];

	err = check_reg_type(env, regno, arg_type, arg_btf_id, meta);
	if (err)
		return err;

	err = check_func_arg_reg_off(env, reg, regno, arg_type);
	if (err)
		return err;

skip_type_check:
	if (arg_type_is_release(arg_type)) {
		if (arg_type_is_dynptr(arg_type)) {
			struct bpf_func_state *state = func(env, reg);
			int spi;

			/* Only dynptr created on stack can be released, thus
			 * the get_spi and stack state checks for spilled_ptr
			 * should only be done before process_dynptr_func for
			 * PTR_TO_STACK.
			 */
			if (reg->type == PTR_TO_STACK) {
				spi = dynptr_get_spi(env, reg);
				if (spi < 0 || !state->stack[spi].spilled_ptr.ref_obj_id) {
					verbose(env, "arg %d is an unacquired reference\n", regno);
					return -EINVAL;
				}
			} else {
				verbose(env, "cannot release unowned const bpf_dynptr\n");
				return -EINVAL;
			}
		} else if (!reg->ref_obj_id && !register_is_null(reg)) {
			verbose(env, "R%d must be referenced when passed to release function\n",
				regno);
			return -EINVAL;
		}
		if (meta->release_regno) {
			verbose(env, "verifier internal error: more than one release argument\n");
			return -EFAULT;
		}
		meta->release_regno = regno;
	}

	if (reg->ref_obj_id && base_type(arg_type) != ARG_KPTR_XCHG_DEST) {
		if (meta->ref_obj_id) {
			verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
				regno, reg->ref_obj_id,
				meta->ref_obj_id);
			return -EFAULT;
		}
		meta->ref_obj_id = reg->ref_obj_id;
	}

	switch (base_type(arg_type)) {
	case ARG_CONST_MAP_PTR:
		/* bpf_map_xxx(map_ptr) call: remember that map_ptr */
		if (meta->map_ptr) {
			/* Use map_uid (which is unique id of inner map) to reject:
			 * inner_map1 = bpf_map_lookup_elem(outer_map, key1)
			 * inner_map2 = bpf_map_lookup_elem(outer_map, key2)
			 * if (inner_map1 && inner_map2) {
			 *     timer = bpf_map_lookup_elem(inner_map1);
			 *     if (timer)
			 *         // mismatch would have been allowed
			 *         bpf_timer_init(timer, inner_map2);
			 * }
			 *
			 * Comparing map_ptr is enough to distinguish normal and outer maps.
			 */
			if (meta->map_ptr != reg->map_ptr ||
			    meta->map_uid != reg->map_uid) {
				verbose(env,
					"timer pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n",
					meta->map_uid, reg->map_uid);
				return -EINVAL;
			}
		}
		meta->map_ptr = reg->map_ptr;
		meta->map_uid = reg->map_uid;
		break;
	case ARG_PTR_TO_MAP_KEY:
		/* bpf_map_xxx(..., map_ptr, ..., key) call:
		 * check that [key, key + map->key_size) are within
		 * stack limits and initialized
		 */
		if (!meta->map_ptr) {
			/* in function declaration map_ptr must come before
			 * map_key, so that it's verified and known before
			 * we have to check map_key here. Otherwise it means
			 * that kernel subsystem misconfigured verifier
			 */
			verbose(env, "invalid map_ptr to access map->key\n");
			return -EACCES;
		}
		err = check_helper_mem_access(env, regno,
					      meta->map_ptr->key_size, false,
					      NULL);
		break;
	case ARG_PTR_TO_MAP_VALUE:
		if (type_may_be_null(arg_type) && register_is_null(reg))
			return 0;

		/* bpf_map_xxx(..., map_ptr, ..., value) call:
		 * check [value, value + map->value_size) validity
		 */
		if (!meta->map_ptr) {
			/* kernel subsystem misconfigured verifier */
			verbose(env, "invalid map_ptr to access map->value\n");
			return -EACCES;
		}
		meta->raw_mode = arg_type & MEM_UNINIT;
		err = check_helper_mem_access(env, regno,
					      meta->map_ptr->value_size, false,
					      meta);
		break;
	case ARG_PTR_TO_PERCPU_BTF_ID:
		if (!reg->btf_id) {
			verbose(env, "Helper has invalid btf_id in R%d\n", regno);
			return -EACCES;
		}
		meta->ret_btf = reg->btf;
		meta->ret_btf_id = reg->btf_id;
		break;
	case ARG_PTR_TO_SPIN_LOCK:
		if (in_rbtree_lock_required_cb(env)) {
			verbose(env, "can't spin_{lock,unlock} in rbtree cb\n");
			return -EACCES;
		}
		if (meta->func_id == BPF_FUNC_spin_lock) {
			err = process_spin_lock(env, regno, true);
			if (err)
				return err;
		} else if (meta->func_id == BPF_FUNC_spin_unlock) {
			err = process_spin_lock(env, regno, false);
			if (err)
				return err;
		} else {
			verbose(env, "verifier internal error\n");
			return -EFAULT;
		}
		break;
	case ARG_PTR_TO_TIMER:
		err = process_timer_func(env, regno, meta);
		if (err)
			return err;
		break;
	case ARG_PTR_TO_FUNC:
		meta->subprogno = reg->subprogno;
		break;
	case ARG_PTR_TO_MEM:
		/* The access to this pointer is only checked when we hit the
		 * next is_mem_size argument below.
		 */
		meta->raw_mode = arg_type & MEM_UNINIT;
		if (arg_type & MEM_FIXED_SIZE) {
			err = check_helper_mem_access(env, regno, fn->arg_size[arg], false, meta);
			if (err)
				return err;
			if (arg_type & MEM_ALIGNED)
				err = check_ptr_alignment(env, reg, 0, fn->arg_size[arg], true);
		}
		break;
	case ARG_CONST_SIZE:
		err = check_mem_size_reg(env, reg, regno, false, meta);
		break;
	case ARG_CONST_SIZE_OR_ZERO:
		err = check_mem_size_reg(env, reg, regno, true, meta);
		break;
	case ARG_PTR_TO_DYNPTR:
		err = process_dynptr_func(env, regno, insn_idx, arg_type, 0);
		if (err)
			return err;
		break;
	case ARG_CONST_ALLOC_SIZE_OR_ZERO:
		if (!tnum_is_const(reg->var_off)) {
			verbose(env, "R%d is not a known constant'\n",
				regno);
			return -EACCES;
		}
		meta->mem_size = reg->var_off.value;
		err = mark_chain_precision(env, regno);
		if (err)
			return err;
		break;
	case ARG_PTR_TO_CONST_STR:
	{
		err = check_reg_const_str(env, reg, regno);
		if (err)
			return err;
		break;
	}
	case ARG_KPTR_XCHG_DEST:
		err = process_kptr_func(env, regno, meta);
		if (err)
			return err;
		break;
	}

	return err;
}

static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id)
{
	enum bpf_attach_type eatype = env->prog->expected_attach_type;
	enum bpf_prog_type type = resolve_prog_type(env->prog);

	if (func_id != BPF_FUNC_map_update_elem &&
	    func_id != BPF_FUNC_map_delete_elem)
		return false;

	/* It's not possible to get access to a locked struct sock in these
	 * contexts, so updating is safe.
	 */
	switch (type) {
	case BPF_PROG_TYPE_TRACING:
		if (eatype == BPF_TRACE_ITER)
			return true;
		break;
	case BPF_PROG_TYPE_SOCK_OPS:
		/* map_update allowed only via dedicated helpers with event type checks */
		if (func_id == BPF_FUNC_map_delete_elem)
			return true;
		break;
	case BPF_PROG_TYPE_SOCKET_FILTER:
	case BPF_PROG_TYPE_SCHED_CLS:
	case BPF_PROG_TYPE_SCHED_ACT:
	case BPF_PROG_TYPE_XDP:
	case BPF_PROG_TYPE_SK_REUSEPORT:
	case BPF_PROG_TYPE_FLOW_DISSECTOR:
	case BPF_PROG_TYPE_SK_LOOKUP:
		return true;
	default:
		break;
	}

	verbose(env, "cannot update sockmap in this context\n");
	return false;
}

static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env)
{
	return env->prog->jit_requested &&
	       bpf_jit_supports_subprog_tailcalls();
}

static int check_map_func_compatibility(struct bpf_verifier_env *env,
					struct bpf_map *map, int func_id)
{
	if (!map)
		return 0;

	/* We need a two way check, first is from map perspective ... */
	switch (map->map_type) {
	case BPF_MAP_TYPE_PROG_ARRAY:
		if (func_id != BPF_FUNC_tail_call)
			goto error;
		break;
	case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
		if (func_id != BPF_FUNC_perf_event_read &&
		    func_id != BPF_FUNC_perf_event_output &&
		    func_id != BPF_FUNC_skb_output &&
		    func_id != BPF_FUNC_perf_event_read_value &&
		    func_id != BPF_FUNC_xdp_output)
			goto error;
		break;
	case BPF_MAP_TYPE_RINGBUF:
		if (func_id != BPF_FUNC_ringbuf_output &&
		    func_id != BPF_FUNC_ringbuf_reserve &&
		    func_id != BPF_FUNC_ringbuf_query &&
		    func_id != BPF_FUNC_ringbuf_reserve_dynptr &&
		    func_id != BPF_FUNC_ringbuf_submit_dynptr &&
		    func_id != BPF_FUNC_ringbuf_discard_dynptr)
			goto error;
		break;
	case BPF_MAP_TYPE_USER_RINGBUF:
		if (func_id != BPF_FUNC_user_ringbuf_drain)
			goto error;
		break;
	case BPF_MAP_TYPE_STACK_TRACE:
		if (func_id != BPF_FUNC_get_stackid)
			goto error;
		break;
	case BPF_MAP_TYPE_CGROUP_ARRAY:
		if (func_id != BPF_FUNC_skb_under_cgroup &&
		    func_id != BPF_FUNC_current_task_under_cgroup)
			goto error;
		break;
	case BPF_MAP_TYPE_CGROUP_STORAGE:
	case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
		if (func_id != BPF_FUNC_get_local_storage)
			goto error;
		break;
	case BPF_MAP_TYPE_DEVMAP:
	case BPF_MAP_TYPE_DEVMAP_HASH:
		if (func_id != BPF_FUNC_redirect_map &&
		    func_id != BPF_FUNC_map_lookup_elem)
			goto error;
		break;
	/* Restrict bpf side of cpumap and xskmap, open when use-cases
	 * appear.
	 */
	case BPF_MAP_TYPE_CPUMAP:
		if (func_id != BPF_FUNC_redirect_map)
			goto error;
		break;
	case BPF_MAP_TYPE_XSKMAP:
		if (func_id != BPF_FUNC_redirect_map &&
		    func_id != BPF_FUNC_map_lookup_elem)
			goto error;
		break;
	case BPF_MAP_TYPE_ARRAY_OF_MAPS:
	case BPF_MAP_TYPE_HASH_OF_MAPS:
		if (func_id != BPF_FUNC_map_lookup_elem)
			goto error;
		break;
	case BPF_MAP_TYPE_SOCKMAP:
		if (func_id != BPF_FUNC_sk_redirect_map &&
		    func_id != BPF_FUNC_sock_map_update &&
		    func_id != BPF_FUNC_msg_redirect_map &&
		    func_id != BPF_FUNC_sk_select_reuseport &&
		    func_id != BPF_FUNC_map_lookup_elem &&
		    !may_update_sockmap(env, func_id))
			goto error;
		break;
	case BPF_MAP_TYPE_SOCKHASH:
		if (func_id != BPF_FUNC_sk_redirect_hash &&
		    func_id != BPF_FUNC_sock_hash_update &&
		    func_id != BPF_FUNC_msg_redirect_hash &&
		    func_id != BPF_FUNC_sk_select_reuseport &&
		    func_id != BPF_FUNC_map_lookup_elem &&
		    !may_update_sockmap(env, func_id))
			goto error;
		break;
	case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
		if (func_id != BPF_FUNC_sk_select_reuseport)
			goto error;
		break;
	case BPF_MAP_TYPE_QUEUE:
	case BPF_MAP_TYPE_STACK:
		if (func_id != BPF_FUNC_map_peek_elem &&
		    func_id != BPF_FUNC_map_pop_elem &&
		    func_id != BPF_FUNC_map_push_elem)
			goto error;
		break;
	case BPF_MAP_TYPE_SK_STORAGE:
		if (func_id != BPF_FUNC_sk_storage_get &&
		    func_id != BPF_FUNC_sk_storage_delete &&
		    func_id != BPF_FUNC_kptr_xchg)
			goto error;
		break;
	case BPF_MAP_TYPE_INODE_STORAGE:
		if (func_id != BPF_FUNC_inode_storage_get &&
		    func_id != BPF_FUNC_inode_storage_delete &&
		    func_id != BPF_FUNC_kptr_xchg)
			goto error;
		break;
	case BPF_MAP_TYPE_TASK_STORAGE:
		if (func_id != BPF_FUNC_task_storage_get &&
		    func_id != BPF_FUNC_task_storage_delete &&
		    func_id != BPF_FUNC_kptr_xchg)
			goto error;
		break;
	case BPF_MAP_TYPE_CGRP_STORAGE:
		if (func_id != BPF_FUNC_cgrp_storage_get &&
		    func_id != BPF_FUNC_cgrp_storage_delete &&
		    func_id != BPF_FUNC_kptr_xchg)
			goto error;
		break;
	case BPF_MAP_TYPE_BLOOM_FILTER:
		if (func_id != BPF_FUNC_map_peek_elem &&
		    func_id != BPF_FUNC_map_push_elem)
			goto error;
		break;
	default:
		break;
	}

	/* ... and second from the function itself. */
	switch (func_id) {
	case BPF_FUNC_tail_call:
		if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
			goto error;
		if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) {
			verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
			return -EINVAL;
		}
		break;
	case BPF_FUNC_perf_event_read:
	case BPF_FUNC_perf_event_output:
	case BPF_FUNC_perf_event_read_value:
	case BPF_FUNC_skb_output:
	case BPF_FUNC_xdp_output:
		if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
			goto error;
		break;
	case BPF_FUNC_ringbuf_output:
	case BPF_FUNC_ringbuf_reserve:
	case BPF_FUNC_ringbuf_query:
	case BPF_FUNC_ringbuf_reserve_dynptr:
	case BPF_FUNC_ringbuf_submit_dynptr:
	case BPF_FUNC_ringbuf_discard_dynptr:
		if (map->map_type != BPF_MAP_TYPE_RINGBUF)
			goto error;
		break;
	case BPF_FUNC_user_ringbuf_drain:
		if (map->map_type != BPF_MAP_TYPE_USER_RINGBUF)
			goto error;
		break;
	case BPF_FUNC_get_stackid:
		if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
			goto error;
		break;
	case BPF_FUNC_current_task_under_cgroup:
	case BPF_FUNC_skb_under_cgroup:
		if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
			goto error;
		break;
	case BPF_FUNC_redirect_map:
		if (map->map_type != BPF_MAP_TYPE_DEVMAP &&
		    map->map_type != BPF_MAP_TYPE_DEVMAP_HASH &&
		    map->map_type != BPF_MAP_TYPE_CPUMAP &&
		    map->map_type != BPF_MAP_TYPE_XSKMAP)
			goto error;
		break;
	case BPF_FUNC_sk_redirect_map:
	case BPF_FUNC_msg_redirect_map:
	case BPF_FUNC_sock_map_update:
		if (map->map_type != BPF_MAP_TYPE_SOCKMAP)
			goto error;
		break;
	case BPF_FUNC_sk_redirect_hash:
	case BPF_FUNC_msg_redirect_hash:
	case BPF_FUNC_sock_hash_update:
		if (map->map_type != BPF_MAP_TYPE_SOCKHASH)
			goto error;
		break;
	case BPF_FUNC_get_local_storage:
		if (map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE &&
		    map->map_type != BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
			goto error;
		break;
	case BPF_FUNC_sk_select_reuseport:
		if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY &&
		    map->map_type != BPF_MAP_TYPE_SOCKMAP &&
		    map->map_type != BPF_MAP_TYPE_SOCKHASH)
			goto error;
		break;
	case BPF_FUNC_map_pop_elem:
		if (map->map_type != BPF_MAP_TYPE_QUEUE &&
		    map->map_type != BPF_MAP_TYPE_STACK)
			goto error;
		break;
	case BPF_FUNC_map_peek_elem:
	case BPF_FUNC_map_push_elem:
		if (map->map_type != BPF_MAP_TYPE_QUEUE &&
		    map->map_type != BPF_MAP_TYPE_STACK &&
		    map->map_type != BPF_MAP_TYPE_BLOOM_FILTER)
			goto error;
		break;
	case BPF_FUNC_map_lookup_percpu_elem:
		if (map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY &&
		    map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
		    map->map_type != BPF_MAP_TYPE_LRU_PERCPU_HASH)
			goto error;
		break;
	case BPF_FUNC_sk_storage_get:
	case BPF_FUNC_sk_storage_delete:
		if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
			goto error;
		break;
	case BPF_FUNC_inode_storage_get:
	case BPF_FUNC_inode_storage_delete:
		if (map->map_type != BPF_MAP_TYPE_INODE_STORAGE)
			goto error;
		break;
	case BPF_FUNC_task_storage_get:
	case BPF_FUNC_task_storage_delete:
		if (map->map_type != BPF_MAP_TYPE_TASK_STORAGE)
			goto error;
		break;
	case BPF_FUNC_cgrp_storage_get:
	case BPF_FUNC_cgrp_storage_delete:
		if (map->map_type != BPF_MAP_TYPE_CGRP_STORAGE)
			goto error;
		break;
	default:
		break;
	}

	return 0;
error:
	verbose(env, "cannot pass map_type %d into func %s#%d\n",
		map->map_type, func_id_name(func_id), func_id);
	return -EINVAL;
}

static bool check_raw_mode_ok(const struct bpf_func_proto *fn)
{
	int count = 0;

	if (arg_type_is_raw_mem(fn->arg1_type))
		count++;
	if (arg_type_is_raw_mem(fn->arg2_type))
		count++;
	if (arg_type_is_raw_mem(fn->arg3_type))
		count++;
	if (arg_type_is_raw_mem(fn->arg4_type))
		count++;
	if (arg_type_is_raw_mem(fn->arg5_type))
		count++;

	/* We only support one arg being in raw mode at the moment,
	 * which is sufficient for the helper functions we have
	 * right now.
	 */
	return count <= 1;
}

static bool check_args_pair_invalid(const struct bpf_func_proto *fn, int arg)
{
	bool is_fixed = fn->arg_type[arg] & MEM_FIXED_SIZE;
	bool has_size = fn->arg_size[arg] != 0;
	bool is_next_size = false;

	if (arg + 1 < ARRAY_SIZE(fn->arg_type))
		is_next_size = arg_type_is_mem_size(fn->arg_type[arg + 1]);

	if (base_type(fn->arg_type[arg]) != ARG_PTR_TO_MEM)
		return is_next_size;

	return has_size == is_next_size || is_next_size == is_fixed;
}

static bool check_arg_pair_ok(const struct bpf_func_proto *fn)
{
	/* bpf_xxx(..., buf, len) call will access 'len'
	 * bytes from memory 'buf'. Both arg types need
	 * to be paired, so make sure there's no buggy
	 * helper function specification.
	 */
	if (arg_type_is_mem_size(fn->arg1_type) ||
	    check_args_pair_invalid(fn, 0) ||
	    check_args_pair_invalid(fn, 1) ||
	    check_args_pair_invalid(fn, 2) ||
	    check_args_pair_invalid(fn, 3) ||
	    check_args_pair_invalid(fn, 4))
		return false;

	return true;
}

static bool check_btf_id_ok(const struct bpf_func_proto *fn)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) {
		if (base_type(fn->arg_type[i]) == ARG_PTR_TO_BTF_ID)
			return !!fn->arg_btf_id[i];
		if (base_type(fn->arg_type[i]) == ARG_PTR_TO_SPIN_LOCK)
			return fn->arg_btf_id[i] == BPF_PTR_POISON;
		if (base_type(fn->arg_type[i]) != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i] &&
		    /* arg_btf_id and arg_size are in a union. */
		    (base_type(fn->arg_type[i]) != ARG_PTR_TO_MEM ||
		     !(fn->arg_type[i] & MEM_FIXED_SIZE)))
			return false;
	}

	return true;
}

static int check_func_proto(const struct bpf_func_proto *fn, int func_id)
{
	return check_raw_mode_ok(fn) &&
	       check_arg_pair_ok(fn) &&
	       check_btf_id_ok(fn) ? 0 : -EINVAL;
}

/* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
 * are now invalid, so turn them into unknown SCALAR_VALUE.
 *
 * This also applies to dynptr slices belonging to skb and xdp dynptrs,
 * since these slices point to packet data.
 */
static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
{
	struct bpf_func_state *state;
	struct bpf_reg_state *reg;

	bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
		if (reg_is_pkt_pointer_any(reg) || reg_is_dynptr_slice_pkt(reg))
			mark_reg_invalid(env, reg);
	}));
}

enum {
	AT_PKT_END = -1,
	BEYOND_PKT_END = -2,
};

static void mark_pkt_end(struct bpf_verifier_state *vstate, int regn, bool range_open)
{
	struct bpf_func_state *state = vstate->frame[vstate->curframe];
	struct bpf_reg_state *reg = &state->regs[regn];

	if (reg->type != PTR_TO_PACKET)
		/* PTR_TO_PACKET_META is not supported yet */
		return;

	/* The 'reg' is pkt > pkt_end or pkt >= pkt_end.
	 * How far beyond pkt_end it goes is unknown.
	 * if (!range_open) it's the case of pkt >= pkt_end
	 * if (range_open) it's the case of pkt > pkt_end
	 * hence this pointer is at least 1 byte bigger than pkt_end
	 */
	if (range_open)
		reg->range = BEYOND_PKT_END;
	else
		reg->range = AT_PKT_END;
}

/* The pointer with the specified id has released its reference to kernel
 * resources. Identify all copies of the same pointer and clear the reference.
 */
static int release_reference(struct bpf_verifier_env *env,
			     int ref_obj_id)
{
	struct bpf_func_state *state;
	struct bpf_reg_state *reg;
	int err;

	err = release_reference_state(cur_func(env), ref_obj_id);
	if (err)
		return err;

	bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
		if (reg->ref_obj_id == ref_obj_id)
			mark_reg_invalid(env, reg);
	}));

	return 0;
}

static void invalidate_non_owning_refs(struct bpf_verifier_env *env)
{
	struct bpf_func_state *unused;
	struct bpf_reg_state *reg;

	bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({
		if (type_is_non_owning_ref(reg->type))
			mark_reg_invalid(env, reg);
	}));
}

static void clear_caller_saved_regs(struct bpf_verifier_env *env,
				    struct bpf_reg_state *regs)
{
	int i;

	/* after the call registers r0 - r5 were scratched */
	for (i = 0; i < CALLER_SAVED_REGS; i++) {
		mark_reg_not_init(env, regs, caller_saved[i]);
		__check_reg_arg(env, regs, caller_saved[i], DST_OP_NO_MARK);
	}
}

typedef int (*set_callee_state_fn)(struct bpf_verifier_env *env,
				   struct bpf_func_state *caller,
				   struct bpf_func_state *callee,
				   int insn_idx);

static int set_callee_state(struct bpf_verifier_env *env,
			    struct bpf_func_state *caller,
			    struct bpf_func_state *callee, int insn_idx);

static int setup_func_entry(struct bpf_verifier_env *env, int subprog, int callsite,
			    set_callee_state_fn set_callee_state_cb,
			    struct bpf_verifier_state *state)
{
	struct bpf_func_state *caller, *callee;
	int err;

	if (state->curframe + 1 >= MAX_CALL_FRAMES) {
		verbose(env, "the call stack of %d frames is too deep\n",
			state->curframe + 2);
		return -E2BIG;
	}

	if (state->frame[state->curframe + 1]) {
		verbose(env, "verifier bug. Frame %d already allocated\n",
			state->curframe + 1);
		return -EFAULT;
	}

	caller = state->frame[state->curframe];
	callee = kzalloc(sizeof(*callee), GFP_KERNEL);
	if (!callee)
		return -ENOMEM;
	state->frame[state->curframe + 1] = callee;

	/* callee cannot access r0, r6 - r9 for reading and has to write
	 * into its own stack before reading from it.
	 * callee can read/write into caller's stack
	 */
	init_func_state(env, callee,
			/* remember the callsite, it will be used by bpf_exit */
			callsite,
			state->curframe + 1 /* frameno within this callchain */,
			subprog /* subprog number within this prog */);
	/* Transfer references to the callee */
	err = copy_reference_state(callee, caller);
	err = err ?: set_callee_state_cb(env, caller, callee, callsite);
	if (err)
		goto err_out;

	/* only increment it after check_reg_arg() finished */
	state->curframe++;

	return 0;

err_out:
	free_func_state(callee);
	state->frame[state->curframe + 1] = NULL;
	return err;
}

static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
				    const struct btf *btf,
				    struct bpf_reg_state *regs)
{
	struct bpf_subprog_info *sub = subprog_info(env, subprog);
	struct bpf_verifier_log *log = &env->log;
	u32 i;
	int ret;

	ret = btf_prepare_func_args(env, subprog);
	if (ret)
		return ret;

	/* check that BTF function arguments match actual types that the
	 * verifier sees.
	 */
	for (i = 0; i < sub->arg_cnt; i++) {
		u32 regno = i + 1;
		struct bpf_reg_state *reg = &regs[regno];
		struct bpf_subprog_arg_info *arg = &sub->args[i];

		if (arg->arg_type == ARG_ANYTHING) {
			if (reg->type != SCALAR_VALUE) {
				bpf_log(log, "R%d is not a scalar\n", regno);
				return -EINVAL;
			}
		} else if (arg->arg_type == ARG_PTR_TO_CTX) {
			ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE);
			if (ret < 0)
				return ret;
			/* If function expects ctx type in BTF check that caller
			 * is passing PTR_TO_CTX.
			 */
			if (reg->type != PTR_TO_CTX) {
				bpf_log(log, "arg#%d expects pointer to ctx\n", i);
				return -EINVAL;
			}
		} else if (base_type(arg->arg_type) == ARG_PTR_TO_MEM) {
			ret = check_func_arg_reg_off(env, reg, regno, ARG_DONTCARE);
			if (ret < 0)
				return ret;
			if (check_mem_reg(env, reg, regno, arg->mem_size))
				return -EINVAL;
			if (!(arg->arg_type & PTR_MAYBE_NULL) && (reg->type & PTR_MAYBE_NULL)) {
				bpf_log(log, "arg#%d is expected to be non-NULL\n", i);
				return -EINVAL;
			}
		} else if (base_type(arg->arg_type) == ARG_PTR_TO_ARENA) {
			/*
			 * Can pass any value and the kernel won't crash, but
			 * only PTR_TO_ARENA or SCALAR make sense. Everything
			 * else is a bug in the bpf program. Point it out to
			 * the user at the verification time instead of
			 * run-time debug nightmare.
			 */
			if (reg->type != PTR_TO_ARENA && reg->type != SCALAR_VALUE) {
				bpf_log(log, "R%d is not a pointer to arena or scalar.\n", regno);
				return -EINVAL;
			}
		} else if (arg->arg_type == (ARG_PTR_TO_DYNPTR | MEM_RDONLY)) {
			ret = check_func_arg_reg_off(env, reg, regno, ARG_PTR_TO_DYNPTR);
			if (ret)
				return ret;

			ret = process_dynptr_func(env, regno, -1, arg->arg_type, 0);
			if (ret)
				return ret;
		} else if (base_type(arg->arg_type) == ARG_PTR_TO_BTF_ID) {
			struct bpf_call_arg_meta meta;
			int err;

			if (register_is_null(reg) && type_may_be_null(arg->arg_type))
				continue;

			memset(&meta, 0, sizeof(meta)); /* leave func_id as zero */
			err = check_reg_type(env, regno, arg->arg_type, &arg->btf_id, &meta);
			err = err ?: check_func_arg_reg_off(env, reg, regno, arg->arg_type);
			if (err)
				return err;
		} else {
			bpf_log(log, "verifier bug: unrecognized arg#%d type %d\n",
				i, arg->arg_type);
			return -EFAULT;
		}
	}

	return 0;
}

/* Compare BTF of a function call with given bpf_reg_state.
 * Returns:
 * EFAULT - there is a verifier bug. Abort verification.
 * EINVAL - there is a type mismatch or BTF is not available.
 * 0 - BTF matches with what bpf_reg_state expects.
 * Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
 */
static int btf_check_subprog_call(struct bpf_verifier_env *env, int subprog,
				  struct bpf_reg_state *regs)
{
	struct bpf_prog *prog = env->prog;
	struct btf *btf = prog->aux->btf;
	u32 btf_id;
	int err;

	if (!prog->aux->func_info)
		return -EINVAL;

	btf_id = prog->aux->func_info[subprog].type_id;
	if (!btf_id)
		return -EFAULT;

	if (prog->aux->func_info_aux[subprog].unreliable)
		return -EINVAL;

	err = btf_check_func_arg_match(env, subprog, btf, regs);
	/* Compiler optimizations can remove arguments from static functions
	 * or mismatched type can be passed into a global function.
	 * In such cases mark the function as unreliable from BTF point of view.
	 */
	if (err)
		prog->aux->func_info_aux[subprog].unreliable = true;
	return err;
}

static int push_callback_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
			      int insn_idx, int subprog,
			      set_callee_state_fn set_callee_state_cb)
{
	struct bpf_verifier_state *state = env->cur_state, *callback_state;
	struct bpf_func_state *caller, *callee;
	int err;

	caller = state->frame[state->curframe];
	err = btf_check_subprog_call(env, subprog, caller->regs);
	if (err == -EFAULT)
		return err;

	/* set_callee_state is used for direct subprog calls, but we are
	 * interested in validating only BPF helpers that can call subprogs as
	 * callbacks
	 */
	env->subprog_info[subprog].is_cb = true;
	if (bpf_pseudo_kfunc_call(insn) &&
	    !is_callback_calling_kfunc(insn->imm)) {
		verbose(env, "verifier bug: kfunc %s#%d not marked as callback-calling\n",
			func_id_name(insn->imm), insn->imm);
		return -EFAULT;
	} else if (!bpf_pseudo_kfunc_call(insn) &&
		   !is_callback_calling_function(insn->imm)) { /* helper */
		verbose(env, "verifier bug: helper %s#%d not marked as callback-calling\n",
			func_id_name(insn->imm), insn->imm);
		return -EFAULT;
	}

	if (is_async_callback_calling_insn(insn)) {
		struct bpf_verifier_state *async_cb;

		/* there is no real recursion here. timer and workqueue callbacks are async */
		env->subprog_info[subprog].is_async_cb = true;
		async_cb = push_async_cb(env, env->subprog_info[subprog].start,
					 insn_idx, subprog,
					 is_bpf_wq_set_callback_impl_kfunc(insn->imm));
		if (!async_cb)
			return -EFAULT;
		callee = async_cb->frame[0];
		callee->async_entry_cnt = caller->async_entry_cnt + 1;

		/* Convert bpf_timer_set_callback() args into timer callback args */
		err = set_callee_state_cb(env, caller, callee, insn_idx);
		if (err)
			return err;

		return 0;
	}

	/* for callback functions enqueue entry to callback and
	 * proceed with next instruction within current frame.
	 */
	callback_state = push_stack(env, env->subprog_info[subprog].start, insn_idx, false);
	if (!callback_state)
		return -ENOMEM;

	err = setup_func_entry(env, subprog, insn_idx, set_callee_state_cb,
			       callback_state);
	if (err)
		return err;

	callback_state->callback_unroll_depth++;
	callback_state->frame[callback_state->curframe - 1]->callback_depth++;
	caller->callback_depth = 0;
	return 0;
}

static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
			   int *insn_idx)
{
	struct bpf_verifier_state *state = env->cur_state;
	struct bpf_func_state *caller;
	int err, subprog, target_insn;

	target_insn = *insn_idx + insn->imm + 1;
	subprog = find_subprog(env, target_insn);
	if (subprog < 0) {
		verbose(env, "verifier bug. No program starts at insn %d\n", target_insn);
		return -EFAULT;
	}

	caller = state->frame[state->curframe];
	err = btf_check_subprog_call(env, subprog, caller->regs);
	if (err == -EFAULT)
		return err;
	if (subprog_is_global(env, subprog)) {
		const char *sub_name = subprog_name(env, subprog);

		/* Only global subprogs cannot be called with a lock held. */
		if (env->cur_state->active_lock.ptr) {
			verbose(env, "global function calls are not allowed while holding a lock,\n"
				     "use static function instead\n");
			return -EINVAL;
		}

		/* Only global subprogs cannot be called with preemption disabled. */
		if (env->cur_state->active_preempt_lock) {
			verbose(env, "global function calls are not allowed with preemption disabled,\n"
				     "use static function instead\n");
			return -EINVAL;
		}

		if (err) {
			verbose(env, "Caller passes invalid args into func#%d ('%s')\n",
				subprog, sub_name);
			return err;
		}

		verbose(env, "Func#%d ('%s') is global and assumed valid.\n",
			subprog, sub_name);
		/* mark global subprog for verifying after main prog */
		subprog_aux(env, subprog)->called = true;
		clear_caller_saved_regs(env, caller->regs);

		/* All global functions return a 64-bit SCALAR_VALUE */
		mark_reg_unknown(env, caller->regs, BPF_REG_0);
		caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;

		/* continue with next insn after call */
		return 0;
	}

	/* for regular function entry setup new frame and continue
	 * from that frame.
	 */
	err = setup_func_entry(env, subprog, *insn_idx, set_callee_state, state);
	if (err)
		return err;

	clear_caller_saved_regs(env, caller->regs);

	/* and go analyze first insn of the callee */
	*insn_idx = env->subprog_info[subprog].start - 1;

	if (env->log.level & BPF_LOG_LEVEL) {
		verbose(env, "caller:\n");
		print_verifier_state(env, caller, true);
		verbose(env, "callee:\n");
		print_verifier_state(env, state->frame[state->curframe], true);
	}

	return 0;
}

int map_set_for_each_callback_args(struct bpf_verifier_env *env,
				   struct bpf_func_state *caller,
				   struct bpf_func_state *callee)
{
	/* bpf_for_each_map_elem(struct bpf_map *map, void *callback_fn,
	 *      void *callback_ctx, u64 flags);
	 * callback_fn(struct bpf_map *map, void *key, void *value,
	 *      void *callback_ctx);
	 */
	callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1];

	callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
	__mark_reg_known_zero(&callee->regs[BPF_REG_2]);
	callee->regs[BPF_REG_2].map_ptr = caller->regs[BPF_REG_1].map_ptr;

	callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
	__mark_reg_known_zero(&callee->regs[BPF_REG_3]);
	callee->regs[BPF_REG_3].map_ptr = caller->regs[BPF_REG_1].map_ptr;

	/* pointer to stack or null */
	callee->regs[BPF_REG_4] = caller->regs[BPF_REG_3];

	/* unused */
	__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
	return 0;
}

static int set_callee_state(struct bpf_verifier_env *env,
			    struct bpf_func_state *caller,
			    struct bpf_func_state *callee, int insn_idx)
{
	int i;

	/* copy r1 - r5 args that callee can access.  The copy includes parent
	 * pointers, which connects us up to the liveness chain
	 */
	for (i = BPF_REG_1; i <= BPF_REG_5; i++)
		callee->regs[i] = caller->regs[i];
	return 0;
}

static int set_map_elem_callback_state(struct bpf_verifier_env *env,
				       struct bpf_func_state *caller,
				       struct bpf_func_state *callee,
				       int insn_idx)
{
	struct bpf_insn_aux_data *insn_aux = &env->insn_aux_data[insn_idx];
	struct bpf_map *map;
	int err;

	/* valid map_ptr and poison value does not matter */
	map = insn_aux->map_ptr_state.map_ptr;
	if (!map->ops->map_set_for_each_callback_args ||
	    !map->ops->map_for_each_callback) {
		verbose(env, "callback function not allowed for map\n");
		return -ENOTSUPP;
	}

	err = map->ops->map_set_for_each_callback_args(env, caller, callee);
	if (err)
		return err;

	callee->in_callback_fn = true;
	callee->callback_ret_range = retval_range(0, 1);
	return 0;
}

static int set_loop_callback_state(struct bpf_verifier_env *env,
				   struct bpf_func_state *caller,
				   struct bpf_func_state *callee,
				   int insn_idx)
{
	/* bpf_loop(u32 nr_loops, void *callback_fn, void *callback_ctx,
	 *	    u64 flags);
	 * callback_fn(u32 index, void *callback_ctx);
	 */
	callee->regs[BPF_REG_1].type = SCALAR_VALUE;
	callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3];

	/* unused */
	__mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
	__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
	__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);

	callee->in_callback_fn = true;
	callee->callback_ret_range = retval_range(0, 1);
	return 0;
}

static int set_timer_callback_state(struct bpf_verifier_env *env,
				    struct bpf_func_state *caller,
				    struct bpf_func_state *callee,
				    int insn_idx)
{
	struct bpf_map *map_ptr = caller->regs[BPF_REG_1].map_ptr;

	/* bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn);
	 * callback_fn(struct bpf_map *map, void *key, void *value);
	 */
	callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP;
	__mark_reg_known_zero(&callee->regs[BPF_REG_1]);
	callee->regs[BPF_REG_1].map_ptr = map_ptr;

	callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY;
	__mark_reg_known_zero(&callee->regs[BPF_REG_2]);
	callee->regs[BPF_REG_2].map_ptr = map_ptr;

	callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE;
	__mark_reg_known_zero(&callee->regs[BPF_REG_3]);
	callee->regs[BPF_REG_3].map_ptr = map_ptr;

	/* unused */
	__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
	__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
	callee->in_async_callback_fn = true;
	callee->callback_ret_range = retval_range(0, 1);
	return 0;
}

static int set_find_vma_callback_state(struct bpf_verifier_env *env,
				       struct bpf_func_state *caller,
				       struct bpf_func_state *callee,
				       int insn_idx)
{
	/* bpf_find_vma(struct task_struct *task, u64 addr,
	 *               void *callback_fn, void *callback_ctx, u64 flags)
	 * (callback_fn)(struct task_struct *task,
	 *               struct vm_area_struct *vma, void *callback_ctx);
	 */
	callee->regs[BPF_REG_1] = caller->regs[BPF_REG_1];

	callee->regs[BPF_REG_2].type = PTR_TO_BTF_ID;
	__mark_reg_known_zero(&callee->regs[BPF_REG_2]);
	callee->regs[BPF_REG_2].btf =  btf_vmlinux;
	callee->regs[BPF_REG_2].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA];

	/* pointer to stack or null */
	callee->regs[BPF_REG_3] = caller->regs[BPF_REG_4];

	/* unused */
	__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
	__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
	callee->in_callback_fn = true;
	callee->callback_ret_range = retval_range(0, 1);
	return 0;
}

static int set_user_ringbuf_callback_state(struct bpf_verifier_env *env,
					   struct bpf_func_state *caller,
					   struct bpf_func_state *callee,
					   int insn_idx)
{
	/* bpf_user_ringbuf_drain(struct bpf_map *map, void *callback_fn, void
	 *			  callback_ctx, u64 flags);
	 * callback_fn(const struct bpf_dynptr_t* dynptr, void *callback_ctx);
	 */
	__mark_reg_not_init(env, &callee->regs[BPF_REG_0]);
	mark_dynptr_cb_reg(env, &callee->regs[BPF_REG_1], BPF_DYNPTR_TYPE_LOCAL);
	callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3];

	/* unused */
	__mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
	__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
	__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);

	callee->in_callback_fn = true;
	callee->callback_ret_range = retval_range(0, 1);
	return 0;
}

static int set_rbtree_add_callback_state(struct bpf_verifier_env *env,
					 struct bpf_func_state *caller,
					 struct bpf_func_state *callee,
					 int insn_idx)
{
	/* void bpf_rbtree_add_impl(struct bpf_rb_root *root, struct bpf_rb_node *node,
	 *                     bool (less)(struct bpf_rb_node *a, const struct bpf_rb_node *b));
	 *
	 * 'struct bpf_rb_node *node' arg to bpf_rbtree_add_impl is the same PTR_TO_BTF_ID w/ offset
	 * that 'less' callback args will be receiving. However, 'node' arg was release_reference'd
	 * by this point, so look at 'root'
	 */
	struct btf_field *field;

	field = reg_find_field_offset(&caller->regs[BPF_REG_1], caller->regs[BPF_REG_1].off,
				      BPF_RB_ROOT);
	if (!field || !field->graph_root.value_btf_id)
		return -EFAULT;

	mark_reg_graph_node(callee->regs, BPF_REG_1, &field->graph_root);
	ref_set_non_owning(env, &callee->regs[BPF_REG_1]);
	mark_reg_graph_node(callee->regs, BPF_REG_2, &field->graph_root);
	ref_set_non_owning(env, &callee->regs[BPF_REG_2]);

	__mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
	__mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
	__mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
	callee->in_callback_fn = true;
	callee->callback_ret_range = retval_range(0, 1);
	return 0;
}

static bool is_rbtree_lock_required_kfunc(u32 btf_id);

/* Are we currently verifying the callback for a rbtree helper that must
 * be called with lock held? If so, no need to complain about unreleased
 * lock
 */
static bool in_rbtree_lock_required_cb(struct bpf_verifier_env *env)
{
	struct bpf_verifier_state *state = env->cur_state;
	struct bpf_insn *insn = env->prog->insnsi;
	struct bpf_func_state *callee;
	int kfunc_btf_id;

	if (!state->curframe)
		return false;

	callee = state->frame[state->curframe];

	if (!callee->in_callback_fn)
		return false;

	kfunc_btf_id = insn[callee->callsite].imm;
	return is_rbtree_lock_required_kfunc(kfunc_btf_id);
}

static bool retval_range_within(struct bpf_retval_range range, const struct bpf_reg_state *reg,
				bool return_32bit)
{
	if (return_32bit)
		return range.minval <= reg->s32_min_value && reg->s32_max_value <= range.maxval;
	else
		return range.minval <= reg->smin_value && reg->smax_value <= range.maxval;
}

static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
{
	struct bpf_verifier_state *state = env->cur_state, *prev_st;
	struct bpf_func_state *caller, *callee;
	struct bpf_reg_state *r0;
	bool in_callback_fn;
	int err;

	callee = state->frame[state->curframe];
	r0 = &callee->regs[BPF_REG_0];
	if (r0->type == PTR_TO_STACK) {
		/* technically it's ok to return caller's stack pointer
		 * (or caller's caller's pointer) back to the caller,
		 * since these pointers are valid. Only current stack
		 * pointer will be invalid as soon as function exits,
		 * but let's be conservative
		 */
		verbose(env, "cannot return stack pointer to the caller\n");
		return -EINVAL;
	}

	caller = state->frame[state->curframe - 1];
	if (callee->in_callback_fn) {
		if (r0->type != SCALAR_VALUE) {
			verbose(env, "R0 not a scalar value\n");
			return -EACCES;
		}

		/* we are going to rely on register's precise value */
		err = mark_reg_read(env, r0, r0->parent, REG_LIVE_READ64);
		err = err ?: mark_chain_precision(env, BPF_REG_0);
		if (err)
			return err;

		/* enforce R0 return value range, and bpf_callback_t returns 64bit */
		if (!retval_range_within(callee->callback_ret_range, r0, false)) {
			verbose_invalid_scalar(env, r0, callee->callback_ret_range,
					       "At callback return", "R0");
			return -EINVAL;
		}
		if (!calls_callback(env, callee->callsite)) {
			verbose(env, "BUG: in callback at %d, callsite %d !calls_callback\n",
				*insn_idx, callee->callsite);
			return -EFAULT;
		}
	} else {
		/* return to the caller whatever r0 had in the callee */
		caller->regs[BPF_REG_0] = *r0;
	}

	/* callback_fn frame should have released its own additions to parent's
	 * reference state at this point, or check_reference_leak would
	 * complain, hence it must be the same as the caller. There is no need
	 * to copy it back.
	 */
	if (!callee->in_callback_fn) {
		/* Transfer references to the caller */
		err = copy_reference_state(caller, callee);
		if (err)
			return err;
	}

	/* for callbacks like bpf_loop or bpf_for_each_map_elem go back to callsite,
	 * there function call logic would reschedule callback visit. If iteration
	 * converges is_state_visited() would prune that visit eventually.
	 */
	in_callback_fn = callee->in_callback_fn;
	if (in_callback_fn)
		*insn_idx = callee->callsite;
	else
		*insn_idx = callee->callsite + 1;

	if (env->log.level & BPF_LOG_LEVEL) {
		verbose(env, "returning from callee:\n");
		print_verifier_state(env, callee, true);
		verbose(env, "to caller at %d:\n", *insn_idx);
		print_verifier_state(env, caller, true);
	}
	/* clear everything in the callee. In case of exceptional exits using
	 * bpf_throw, this will be done by copy_verifier_state for extra frames. */
	free_func_state(callee);
	state->frame[state->curframe--] = NULL;

	/* for callbacks widen imprecise scalars to make programs like below verify:
	 *
	 *   struct ctx { int i; }
	 *   void cb(int idx, struct ctx *ctx) { ctx->i++; ... }
	 *   ...
	 *   struct ctx = { .i = 0; }
	 *   bpf_loop(100, cb, &ctx, 0);
	 *
	 * This is similar to what is done in process_iter_next_call() for open
	 * coded iterators.
	 */
	prev_st = in_callback_fn ? find_prev_entry(env, state, *insn_idx) : NULL;
	if (prev_st) {
		err = widen_imprecise_scalars(env, prev_st, state);
		if (err)
			return err;
	}
	return 0;
}

static int do_refine_retval_range(struct bpf_verifier_env *env,
				  struct bpf_reg_state *regs, int ret_type,
				  int func_id,
				  struct bpf_call_arg_meta *meta)
{
	struct bpf_reg_state *ret_reg = &regs[BPF_REG_0];

	if (ret_type != RET_INTEGER)
		return 0;

	switch (func_id) {
	case BPF_FUNC_get_stack:
	case BPF_FUNC_get_task_stack:
	case BPF_FUNC_probe_read_str:
	case BPF_FUNC_probe_read_kernel_str:
	case BPF_FUNC_probe_read_user_str:
		ret_reg->smax_value = meta->msize_max_value;
		ret_reg->s32_max_value = meta->msize_max_value;
		ret_reg->smin_value = -MAX_ERRNO;
		ret_reg->s32_min_value = -MAX_ERRNO;
		reg_bounds_sync(ret_reg);
		break;
	case BPF_FUNC_get_smp_processor_id:
		ret_reg->umax_value = nr_cpu_ids - 1;
		ret_reg->u32_max_value = nr_cpu_ids - 1;
		ret_reg->smax_value = nr_cpu_ids - 1;
		ret_reg->s32_max_value = nr_cpu_ids - 1;
		ret_reg->umin_value = 0;
		ret_reg->u32_min_value = 0;
		ret_reg->smin_value = 0;
		ret_reg->s32_min_value = 0;
		reg_bounds_sync(ret_reg);
		break;
	}

	return reg_bounds_sanity_check(env, ret_reg, "retval");
}

static int
record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
		int func_id, int insn_idx)
{
	struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
	struct bpf_map *map = meta->map_ptr;

	if (func_id != BPF_FUNC_tail_call &&
	    func_id != BPF_FUNC_map_lookup_elem &&
	    func_id != BPF_FUNC_map_update_elem &&
	    func_id != BPF_FUNC_map_delete_elem &&
	    func_id != BPF_FUNC_map_push_elem &&
	    func_id != BPF_FUNC_map_pop_elem &&
	    func_id != BPF_FUNC_map_peek_elem &&
	    func_id != BPF_FUNC_for_each_map_elem &&
	    func_id != BPF_FUNC_redirect_map &&
	    func_id != BPF_FUNC_map_lookup_percpu_elem)
		return 0;

	if (map == NULL) {
		verbose(env, "kernel subsystem misconfigured verifier\n");
		return -EINVAL;
	}

	/* In case of read-only, some additional restrictions
	 * need to be applied in order to prevent altering the
	 * state of the map from program side.
	 */
	if ((map->map_flags & BPF_F_RDONLY_PROG) &&
	    (func_id == BPF_FUNC_map_delete_elem ||
	     func_id == BPF_FUNC_map_update_elem ||
	     func_id == BPF_FUNC_map_push_elem ||
	     func_id == BPF_FUNC_map_pop_elem)) {
		verbose(env, "write into map forbidden\n");
		return -EACCES;
	}

	if (!aux->map_ptr_state.map_ptr)
		bpf_map_ptr_store(aux, meta->map_ptr,
				  !meta->map_ptr->bypass_spec_v1, false);
	else if (aux->map_ptr_state.map_ptr != meta->map_ptr)
		bpf_map_ptr_store(aux, meta->map_ptr,
				  !meta->map_ptr->bypass_spec_v1, true);
	return 0;
}

static int
record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
		int func_id, int insn_idx)
{
	struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
	struct bpf_reg_state *regs = cur_regs(env), *reg;
	struct bpf_map *map = meta->map_ptr;
	u64 val, max;
	int err;

	if (func_id != BPF_FUNC_tail_call)
		return 0;
	if (!map || map->map_type != BPF_MAP_TYPE_PROG_ARRAY) {
		verbose(env, "kernel subsystem misconfigured verifier\n");
		return -EINVAL;
	}

	reg = &regs[BPF_REG_3];
	val = reg->var_off.value;
	max = map->max_entries;

	if (!(is_reg_const(reg, false) && val < max)) {
		bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
		return 0;
	}

	err = mark_chain_precision(env, BPF_REG_3);
	if (err)
		return err;
	if (bpf_map_key_unseen(aux))
		bpf_map_key_store(aux, val);
	else if (!bpf_map_key_poisoned(aux) &&
		  bpf_map_key_immediate(aux) != val)
		bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
	return 0;
}

static int check_reference_leak(struct bpf_verifier_env *env, bool exception_exit)
{
	struct bpf_func_state *state = cur_func(env);
	bool refs_lingering = false;
	int i;

	if (!exception_exit && state->frameno && !state->in_callback_fn)
		return 0;

	for (i = 0; i < state->acquired_refs; i++) {
		if (!exception_exit && state->in_callback_fn && state->refs[i].callback_ref != state->frameno)
			continue;
		verbose(env, "Unreleased reference id=%d alloc_insn=%d\n",
			state->refs[i].id, state->refs[i].insn_idx);
		refs_lingering = true;
	}
	return refs_lingering ? -EINVAL : 0;
}

static int check_bpf_snprintf_call(struct bpf_verifier_env *env,
				   struct bpf_reg_state *regs)
{
	struct bpf_reg_state *fmt_reg = &regs[BPF_REG_3];
	struct bpf_reg_state *data_len_reg = &regs[BPF_REG_5];
	struct bpf_map *fmt_map = fmt_reg->map_ptr;
	struct bpf_bprintf_data data = {};
	int err, fmt_map_off, num_args;
	u64 fmt_addr;
	char *fmt;

	/* data must be an array of u64 */
	if (data_len_reg->var_off.value % 8)
		return -EINVAL;
	num_args = data_len_reg->var_off.value / 8;

	/* fmt being ARG_PTR_TO_CONST_STR guarantees that var_off is const
	 * and map_direct_value_addr is set.
	 */
	fmt_map_off = fmt_reg->off + fmt_reg->var_off.value;
	err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr,
						  fmt_map_off);
	if (err) {
		verbose(env, "verifier bug\n");
		return -EFAULT;
	}
	fmt = (char *)(long)fmt_addr + fmt_map_off;

	/* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we
	 * can focus on validating the format specifiers.
	 */
	err = bpf_bprintf_prepare(fmt, UINT_MAX, NULL, num_args, &data);
	if (err < 0)
		verbose(env, "Invalid format string\n");

	return err;
}

static int check_get_func_ip(struct bpf_verifier_env *env)
{
	enum bpf_prog_type type = resolve_prog_type(env->prog);
	int func_id = BPF_FUNC_get_func_ip;

	if (type == BPF_PROG_TYPE_TRACING) {
		if (!bpf_prog_has_trampoline(env->prog)) {
			verbose(env, "func %s#%d supported only for fentry/fexit/fmod_ret programs\n",
				func_id_name(func_id), func_id);
			return -ENOTSUPP;
		}
		return 0;
	} else if (type == BPF_PROG_TYPE_KPROBE) {
		return 0;
	}

	verbose(env, "func %s#%d not supported for program type %d\n",
		func_id_name(func_id), func_id, type);
	return -ENOTSUPP;
}

static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env)
{
	return &env->insn_aux_data[env->insn_idx];
}

static bool loop_flag_is_zero(struct bpf_verifier_env *env)
{
	struct bpf_reg_state *regs = cur_regs(env);
	struct bpf_reg_state *reg = &regs[BPF_REG_4];
	bool reg_is_null = register_is_null(reg);

	if (reg_is_null)
		mark_chain_precision(env, BPF_REG_4);

	return reg_is_null;
}

static void update_loop_inline_state(struct bpf_verifier_env *env, u32 subprogno)
{
	struct bpf_loop_inline_state *state = &cur_aux(env)->loop_inline_state;

	if (!state->initialized) {
		state->initialized = 1;
		state->fit_for_inline = loop_flag_is_zero(env);
		state->callback_subprogno = subprogno;
		return;
	}

	if (!state->fit_for_inline)
		return;

	state->fit_for_inline = (loop_flag_is_zero(env) &&
				 state->callback_subprogno == subprogno);
}

static int get_helper_proto(struct bpf_verifier_env *env, int func_id,
			    const struct bpf_func_proto **ptr)
{
	if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID)
		return -ERANGE;

	if (!env->ops->get_func_proto)
		return -EINVAL;

	*ptr = env->ops->get_func_proto(func_id, env->prog);
	return *ptr ? 0 : -EINVAL;
}

static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
			     int *insn_idx_p)
{
	enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
	bool returns_cpu_specific_alloc_ptr = false;
	const struct bpf_func_proto *fn = NULL;
	enum bpf_return_type ret_type;
	enum bpf_type_flag ret_flag;
	struct bpf_reg_state *regs;
	struct bpf_call_arg_meta meta;
	int insn_idx = *insn_idx_p;
	bool changes_data;
	int i, err, func_id;

	/* find function prototype */
	func_id = insn->imm;
	err = get_helper_proto(env, insn->imm, &fn);
	if (err == -ERANGE) {
		verbose(env, "invalid func %s#%d\n", func_id_name(func_id), func_id);
		return -EINVAL;
	}

	if (err) {
		verbose(env, "program of this type cannot use helper %s#%d\n",
			func_id_name(func_id), func_id);
		return err;
	}

	/* eBPF programs must be GPL compatible to use GPL-ed functions */
	if (!env->prog->gpl_compatible && fn->gpl_only) {
		verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n");
		return -EINVAL;
	}

	if (fn->allowed && !fn->allowed(env->prog)) {
		verbose(env, "helper call is not allowed in probe\n");
		return -EINVAL;
	}

	if (!in_sleepable(env) && fn->might_sleep) {
		verbose(env, "helper call might sleep in a non-sleepable prog\n");
		return -EINVAL;
	}

	/* With LD_ABS/IND some JITs save/restore skb from r1. */
	changes_data = bpf_helper_changes_pkt_data(fn->func);
	if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {
		verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n",
			func_id_name(func_id), func_id);
		return -EINVAL;
	}

	memset(&meta, 0, sizeof(meta));
	meta.pkt_access = fn->pkt_access;

	err = check_func_proto(fn, func_id);
	if (err) {
		verbose(env, "kernel subsystem misconfigured func %s#%d\n",
			func_id_name(func_id), func_id);
		return err;
	}

	if (env->cur_state->active_rcu_lock) {
		if (fn->might_sleep) {
			verbose(env, "sleepable helper %s#%d in rcu_read_lock region\n",
				func_id_name(func_id), func_id);
			return -EINVAL;
		}

		if (in_sleepable(env) && is_storage_get_function(func_id))
			env->insn_aux_data[insn_idx].storage_get_func_atomic = true;
	}

	if (env->cur_state->active_preempt_lock) {
		if (fn->might_sleep) {
			verbose(env, "sleepable helper %s#%d in non-preemptible region\n",
				func_id_name(func_id), func_id);
			return -EINVAL;
		}

		if (in_sleepable(env) && is_storage_get_function(func_id))
			env->insn_aux_data[insn_idx].storage_get_func_atomic = true;
	}

	meta.func_id = func_id;
	/* check args */
	for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
		err = check_func_arg(env, i, &meta, fn, insn_idx);
		if (err)
			return err;
	}

	err = record_func_map(env, &meta, func_id, insn_idx);
	if (err)
		return err;

	err = record_func_key(env, &meta, func_id, insn_idx);
	if (err)
		return err;

	/* Mark slots with STACK_MISC in case of raw mode, stack offset
	 * is inferred from register state.
	 */
	for (i = 0; i < meta.access_size; i++) {
		err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B,
				       BPF_WRITE, -1, false, false);
		if (err)
			return err;
	}

	regs = cur_regs(env);

	if (meta.release_regno) {
		err = -EINVAL;
		/* This can only be set for PTR_TO_STACK, as CONST_PTR_TO_DYNPTR cannot
		 * be released by any dynptr helper. Hence, unmark_stack_slots_dynptr
		 * is safe to do directly.
		 */
		if (arg_type_is_dynptr(fn->arg_type[meta.release_regno - BPF_REG_1])) {
			if (regs[meta.release_regno].type == CONST_PTR_TO_DYNPTR) {
				verbose(env, "verifier internal error: CONST_PTR_TO_DYNPTR cannot be released\n");
				return -EFAULT;
			}
			err = unmark_stack_slots_dynptr(env, &regs[meta.release_regno]);
		} else if (func_id == BPF_FUNC_kptr_xchg && meta.ref_obj_id) {
			u32 ref_obj_id = meta.ref_obj_id;
			bool in_rcu = in_rcu_cs(env);
			struct bpf_func_state *state;
			struct bpf_reg_state *reg;

			err = release_reference_state(cur_func(env), ref_obj_id);
			if (!err) {
				bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
					if (reg->ref_obj_id == ref_obj_id) {
						if (in_rcu && (reg->type & MEM_ALLOC) && (reg->type & MEM_PERCPU)) {
							reg->ref_obj_id = 0;
							reg->type &= ~MEM_ALLOC;
							reg->type |= MEM_RCU;
						} else {
							mark_reg_invalid(env, reg);
						}
					}
				}));
			}
		} else if (meta.ref_obj_id) {
			err = release_reference(env, meta.ref_obj_id);
		} else if (register_is_null(&regs[meta.release_regno])) {
			/* meta.ref_obj_id can only be 0 if register that is meant to be
			 * released is NULL, which must be > R0.
			 */
			err = 0;
		}
		if (err) {
			verbose(env, "func %s#%d reference has not been acquired before\n",
				func_id_name(func_id), func_id);
			return err;
		}
	}

	switch (func_id) {
	case BPF_FUNC_tail_call:
		err = check_reference_leak(env, false);
		if (err) {
			verbose(env, "tail_call would lead to reference leak\n");
			return err;
		}
		break;
	case BPF_FUNC_get_local_storage:
		/* check that flags argument in get_local_storage(map, flags) is 0,
		 * this is required because get_local_storage() can't return an error.
		 */
		if (!register_is_null(&regs[BPF_REG_2])) {
			verbose(env, "get_local_storage() doesn't support non-zero flags\n");
			return -EINVAL;
		}
		break;
	case BPF_FUNC_for_each_map_elem:
		err = push_callback_call(env, insn, insn_idx, meta.subprogno,
					 set_map_elem_callback_state);
		break;
	case BPF_FUNC_timer_set_callback:
		err = push_callback_call(env, insn, insn_idx, meta.subprogno,
					 set_timer_callback_state);
		break;
	case BPF_FUNC_find_vma:
		err = push_callback_call(env, insn, insn_idx, meta.subprogno,
					 set_find_vma_callback_state);
		break;
	case BPF_FUNC_snprintf:
		err = check_bpf_snprintf_call(env, regs);
		break;
	case BPF_FUNC_loop:
		update_loop_inline_state(env, meta.subprogno);
		/* Verifier relies on R1 value to determine if bpf_loop() iteration
		 * is finished, thus mark it precise.
		 */
		err = mark_chain_precision(env, BPF_REG_1);
		if (err)
			return err;
		if (cur_func(env)->callback_depth < regs[BPF_REG_1].umax_value) {
			err = push_callback_call(env, insn, insn_idx, meta.subprogno,
						 set_loop_callback_state);
		} else {
			cur_func(env)->callback_depth = 0;
			if (env->log.level & BPF_LOG_LEVEL2)
				verbose(env, "frame%d bpf_loop iteration limit reached\n",
					env->cur_state->curframe);
		}
		break;
	case BPF_FUNC_dynptr_from_mem:
		if (regs[BPF_REG_1].type != PTR_TO_MAP_VALUE) {
			verbose(env, "Unsupported reg type %s for bpf_dynptr_from_mem data\n",
				reg_type_str(env, regs[BPF_REG_1].type));
			return -EACCES;
		}
		break;
	case BPF_FUNC_set_retval:
		if (prog_type == BPF_PROG_TYPE_LSM &&
		    env->prog->expected_attach_type == BPF_LSM_CGROUP) {
			if (!env->prog->aux->attach_func_proto->type) {
				/* Make sure programs that attach to void
				 * hooks don't try to modify return value.
				 */
				verbose(env, "BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n");
				return -EINVAL;
			}
		}
		break;
	case BPF_FUNC_dynptr_data:
	{
		struct bpf_reg_state *reg;
		int id, ref_obj_id;

		reg = get_dynptr_arg_reg(env, fn, regs);
		if (!reg)
			return -EFAULT;


		if (meta.dynptr_id) {
			verbose(env, "verifier internal error: meta.dynptr_id already set\n");
			return -EFAULT;
		}
		if (meta.ref_obj_id) {
			verbose(env, "verifier internal error: meta.ref_obj_id already set\n");
			return -EFAULT;
		}

		id = dynptr_id(env, reg);
		if (id < 0) {
			verbose(env, "verifier internal error: failed to obtain dynptr id\n");
			return id;
		}

		ref_obj_id = dynptr_ref_obj_id(env, reg);
		if (ref_obj_id < 0) {
			verbose(env, "verifier internal error: failed to obtain dynptr ref_obj_id\n");
			return ref_obj_id;
		}

		meta.dynptr_id = id;
		meta.ref_obj_id = ref_obj_id;

		break;
	}
	case BPF_FUNC_dynptr_write:
	{
		enum bpf_dynptr_type dynptr_type;
		struct bpf_reg_state *reg;

		reg = get_dynptr_arg_reg(env, fn, regs);
		if (!reg)
			return -EFAULT;

		dynptr_type = dynptr_get_type(env, reg);
		if (dynptr_type == BPF_DYNPTR_TYPE_INVALID)
			return -EFAULT;

		if (dynptr_type == BPF_DYNPTR_TYPE_SKB)
			/* this will trigger clear_all_pkt_pointers(), which will
			 * invalidate all dynptr slices associated with the skb
			 */
			changes_data = true;

		break;
	}
	case BPF_FUNC_per_cpu_ptr:
	case BPF_FUNC_this_cpu_ptr:
	{
		struct bpf_reg_state *reg = &regs[BPF_REG_1];
		const struct btf_type *type;

		if (reg->type & MEM_RCU) {
			type = btf_type_by_id(reg->btf, reg->btf_id);
			if (!type || !btf_type_is_struct(type)) {
				verbose(env, "Helper has invalid btf/btf_id in R1\n");
				return -EFAULT;
			}
			returns_cpu_specific_alloc_ptr = true;
			env->insn_aux_data[insn_idx].call_with_percpu_alloc_ptr = true;
		}
		break;
	}
	case BPF_FUNC_user_ringbuf_drain:
		err = push_callback_call(env, insn, insn_idx, meta.subprogno,
					 set_user_ringbuf_callback_state);
		break;
	}

	if (err)
		return err;

	/* reset caller saved regs */
	for (i = 0; i < CALLER_SAVED_REGS; i++) {
		mark_reg_not_init(env, regs, caller_saved[i]);
		check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
	}

	/* helper call returns 64-bit value. */
	regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;

	/* update return register (already marked as written above) */
	ret_type = fn->ret_type;
	ret_flag = type_flag(ret_type);

	switch (base_type(ret_type)) {
	case RET_INTEGER:
		/* sets type to SCALAR_VALUE */
		mark_reg_unknown(env, regs, BPF_REG_0);
		break;
	case RET_VOID:
		regs[BPF_REG_0].type = NOT_INIT;
		break;
	case RET_PTR_TO_MAP_VALUE:
		/* There is no offset yet applied, variable or fixed */
		mark_reg_known_zero(env, regs, BPF_REG_0);
		/* remember map_ptr, so that check_map_access()
		 * can check 'value_size' boundary of memory access
		 * to map element returned from bpf_map_lookup_elem()
		 */
		if (meta.map_ptr == NULL) {
			verbose(env,
				"kernel subsystem misconfigured verifier\n");
			return -EINVAL;
		}
		regs[BPF_REG_0].map_ptr = meta.map_ptr;
		regs[BPF_REG_0].map_uid = meta.map_uid;
		regs[BPF_REG_0].type = PTR_TO_MAP_VALUE | ret_flag;
		if (!type_may_be_null(ret_type) &&
		    btf_record_has_field(meta.map_ptr->record, BPF_SPIN_LOCK)) {
			regs[BPF_REG_0].id = ++env->id_gen;
		}
		break;
	case RET_PTR_TO_SOCKET:
		mark_reg_known_zero(env, regs, BPF_REG_0);
		regs[BPF_REG_0].type = PTR_TO_SOCKET | ret_flag;
		break;
	case RET_PTR_TO_SOCK_COMMON:
		mark_reg_known_zero(env, regs, BPF_REG_0);
		regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON | ret_flag;
		break;
	case RET_PTR_TO_TCP_SOCK:
		mark_reg_known_zero(env, regs, BPF_REG_0);
		regs[BPF_REG_0].type = PTR_TO_TCP_SOCK | ret_flag;
		break;
	case RET_PTR_TO_MEM:
		mark_reg_known_zero(env, regs, BPF_REG_0);
		regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
		regs[BPF_REG_0].mem_size = meta.mem_size;
		break;
	case RET_PTR_TO_MEM_OR_BTF_ID:
	{
		const struct btf_type *t;

		mark_reg_known_zero(env, regs, BPF_REG_0);
		t = btf_type_skip_modifiers(meta.ret_btf, meta.ret_btf_id, NULL);
		if (!btf_type_is_struct(t)) {
			u32 tsize;
			const struct btf_type *ret;
			const char *tname;

			/* resolve the type size of ksym. */
			ret = btf_resolve_size(meta.ret_btf, t, &tsize);
			if (IS_ERR(ret)) {
				tname = btf_name_by_offset(meta.ret_btf, t->name_off);
				verbose(env, "unable to resolve the size of type '%s': %ld\n",
					tname, PTR_ERR(ret));
				return -EINVAL;
			}
			regs[BPF_REG_0].type = PTR_TO_MEM | ret_flag;
			regs[BPF_REG_0].mem_size = tsize;
		} else {
			if (returns_cpu_specific_alloc_ptr) {
				regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC | MEM_RCU;
			} else {
				/* MEM_RDONLY may be carried from ret_flag, but it
				 * doesn't apply on PTR_TO_BTF_ID. Fold it, otherwise
				 * it will confuse the check of PTR_TO_BTF_ID in
				 * check_mem_access().
				 */
				ret_flag &= ~MEM_RDONLY;
				regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
			}

			regs[BPF_REG_0].btf = meta.ret_btf;
			regs[BPF_REG_0].btf_id = meta.ret_btf_id;
		}
		break;
	}
	case RET_PTR_TO_BTF_ID:
	{
		struct btf *ret_btf;
		int ret_btf_id;

		mark_reg_known_zero(env, regs, BPF_REG_0);
		regs[BPF_REG_0].type = PTR_TO_BTF_ID | ret_flag;
		if (func_id == BPF_FUNC_kptr_xchg) {
			ret_btf = meta.kptr_field->kptr.btf;
			ret_btf_id = meta.kptr_field->kptr.btf_id;
			if (!btf_is_kernel(ret_btf)) {
				regs[BPF_REG_0].type |= MEM_ALLOC;
				if (meta.kptr_field->type == BPF_KPTR_PERCPU)
					regs[BPF_REG_0].type |= MEM_PERCPU;
			}
		} else {
			if (fn->ret_btf_id == BPF_PTR_POISON) {
				verbose(env, "verifier internal error:");
				verbose(env, "func %s has non-overwritten BPF_PTR_POISON return type\n",
					func_id_name(func_id));
				return -EINVAL;
			}
			ret_btf = btf_vmlinux;
			ret_btf_id = *fn->ret_btf_id;
		}
		if (ret_btf_id == 0) {
			verbose(env, "invalid return type %u of func %s#%d\n",
				base_type(ret_type), func_id_name(func_id),
				func_id);
			return -EINVAL;
		}
		regs[BPF_REG_0].btf = ret_btf;
		regs[BPF_REG_0].btf_id = ret_btf_id;
		break;
	}
	default:
		verbose(env, "unknown return type %u of func %s#%d\n",
			base_type(ret_type), func_id_name(func_id), func_id);
		return -EINVAL;
	}

	if (type_may_be_null(regs[BPF_REG_0].type))
		regs[BPF_REG_0].id = ++env->id_gen;

	if (helper_multiple_ref_obj_use(func_id, meta.map_ptr)) {
		verbose(env, "verifier internal error: func %s#%d sets ref_obj_id more than once\n",
			func_id_name(func_id), func_id);
		return -EFAULT;
	}

	if (is_dynptr_ref_function(func_id))
		regs[BPF_REG_0].dynptr_id = meta.dynptr_id;

	if (is_ptr_cast_function(func_id) || is_dynptr_ref_function(func_id)) {
		/* For release_reference() */
		regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
	} else if (is_acquire_function(func_id, meta.map_ptr)) {
		int id = acquire_reference_state(env, insn_idx);

		if (id < 0)
			return id;
		/* For mark_ptr_or_null_reg() */
		regs[BPF_REG_0].id = id;
		/* For release_reference() */
		regs[BPF_REG_0].ref_obj_id = id;
	}

	err = do_refine_retval_range(env, regs, fn->ret_type, func_id, &meta);
	if (err)
		return err;

	err = check_map_func_compatibility(env, meta.map_ptr, func_id);
	if (err)
		return err;

	if ((func_id == BPF_FUNC_get_stack ||
	     func_id == BPF_FUNC_get_task_stack) &&
	    !env->prog->has_callchain_buf) {
		const char *err_str;

#ifdef CONFIG_PERF_EVENTS
		err = get_callchain_buffers(sysctl_perf_event_max_stack);
		err_str = "cannot get callchain buffer for func %s#%d\n";
#else
		err = -ENOTSUPP;
		err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n";
#endif
		if (err) {
			verbose(env, err_str, func_id_name(func_id), func_id);
			return err;
		}

		env->prog->has_callchain_buf = true;
	}

	if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack)
		env->prog->call_get_stack = true;

	if (func_id == BPF_FUNC_get_func_ip) {
		if (check_get_func_ip(env))
			return -ENOTSUPP;
		env->prog->call_get_func_ip = true;
	}

	if (changes_data)
		clear_all_pkt_pointers(env);
	return 0;
}

/* mark_btf_func_reg_size() is used when the reg size is determined by
 * the BTF func_proto's return value size and argument.
 */
static void mark_btf_func_reg_size(struct bpf_verifier_env *env, u32 regno,
				   size_t reg_size)
{
	struct bpf_reg_state *reg = &cur_regs(env)[regno];

	if (regno == BPF_REG_0) {
		/* Function return value */
		reg->live |= REG_LIVE_WRITTEN;
		reg->subreg_def = reg_size == sizeof(u64) ?
			DEF_NOT_SUBREG : env->insn_idx + 1;
	} else {
		/* Function argument */
		if (reg_size == sizeof(u64)) {
			mark_insn_zext(env, reg);
			mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
		} else {
			mark_reg_read(env, reg, reg->parent, REG_LIVE_READ32);
		}
	}
}

static bool is_kfunc_acquire(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->kfunc_flags & KF_ACQUIRE;
}

static bool is_kfunc_release(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->kfunc_flags & KF_RELEASE;
}

static bool is_kfunc_trusted_args(struct bpf_kfunc_call_arg_meta *meta)
{
	return (meta->kfunc_flags & KF_TRUSTED_ARGS) || is_kfunc_release(meta);
}

static bool is_kfunc_sleepable(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->kfunc_flags & KF_SLEEPABLE;
}

static bool is_kfunc_destructive(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->kfunc_flags & KF_DESTRUCTIVE;
}

static bool is_kfunc_rcu(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->kfunc_flags & KF_RCU;
}

static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->kfunc_flags & KF_RCU_PROTECTED;
}

static bool is_kfunc_arg_mem_size(const struct btf *btf,
				  const struct btf_param *arg,
				  const struct bpf_reg_state *reg)
{
	const struct btf_type *t;

	t = btf_type_skip_modifiers(btf, arg->type, NULL);
	if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
		return false;

	return btf_param_match_suffix(btf, arg, "__sz");
}

static bool is_kfunc_arg_const_mem_size(const struct btf *btf,
					const struct btf_param *arg,
					const struct bpf_reg_state *reg)
{
	const struct btf_type *t;

	t = btf_type_skip_modifiers(btf, arg->type, NULL);
	if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
		return false;

	return btf_param_match_suffix(btf, arg, "__szk");
}

static bool is_kfunc_arg_optional(const struct btf *btf, const struct btf_param *arg)
{
	return btf_param_match_suffix(btf, arg, "__opt");
}

static bool is_kfunc_arg_constant(const struct btf *btf, const struct btf_param *arg)
{
	return btf_param_match_suffix(btf, arg, "__k");
}

static bool is_kfunc_arg_ignore(const struct btf *btf, const struct btf_param *arg)
{
	return btf_param_match_suffix(btf, arg, "__ign");
}

static bool is_kfunc_arg_map(const struct btf *btf, const struct btf_param *arg)
{
	return btf_param_match_suffix(btf, arg, "__map");
}

static bool is_kfunc_arg_alloc_obj(const struct btf *btf, const struct btf_param *arg)
{
	return btf_param_match_suffix(btf, arg, "__alloc");
}

static bool is_kfunc_arg_uninit(const struct btf *btf, const struct btf_param *arg)
{
	return btf_param_match_suffix(btf, arg, "__uninit");
}

static bool is_kfunc_arg_refcounted_kptr(const struct btf *btf, const struct btf_param *arg)
{
	return btf_param_match_suffix(btf, arg, "__refcounted_kptr");
}

static bool is_kfunc_arg_nullable(const struct btf *btf, const struct btf_param *arg)
{
	return btf_param_match_suffix(btf, arg, "__nullable");
}

static bool is_kfunc_arg_const_str(const struct btf *btf, const struct btf_param *arg)
{
	return btf_param_match_suffix(btf, arg, "__str");
}

static bool is_kfunc_arg_scalar_with_name(const struct btf *btf,
					  const struct btf_param *arg,
					  const char *name)
{
	int len, target_len = strlen(name);
	const char *param_name;

	param_name = btf_name_by_offset(btf, arg->name_off);
	if (str_is_empty(param_name))
		return false;
	len = strlen(param_name);
	if (len != target_len)
		return false;
	if (strcmp(param_name, name))
		return false;

	return true;
}

enum {
	KF_ARG_DYNPTR_ID,
	KF_ARG_LIST_HEAD_ID,
	KF_ARG_LIST_NODE_ID,
	KF_ARG_RB_ROOT_ID,
	KF_ARG_RB_NODE_ID,
	KF_ARG_WORKQUEUE_ID,
};

BTF_ID_LIST(kf_arg_btf_ids)
BTF_ID(struct, bpf_dynptr)
BTF_ID(struct, bpf_list_head)
BTF_ID(struct, bpf_list_node)
BTF_ID(struct, bpf_rb_root)
BTF_ID(struct, bpf_rb_node)
BTF_ID(struct, bpf_wq)

static bool __is_kfunc_ptr_arg_type(const struct btf *btf,
				    const struct btf_param *arg, int type)
{
	const struct btf_type *t;
	u32 res_id;

	t = btf_type_skip_modifiers(btf, arg->type, NULL);
	if (!t)
		return false;
	if (!btf_type_is_ptr(t))
		return false;
	t = btf_type_skip_modifiers(btf, t->type, &res_id);
	if (!t)
		return false;
	return btf_types_are_same(btf, res_id, btf_vmlinux, kf_arg_btf_ids[type]);
}

static bool is_kfunc_arg_dynptr(const struct btf *btf, const struct btf_param *arg)
{
	return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_DYNPTR_ID);
}

static bool is_kfunc_arg_list_head(const struct btf *btf, const struct btf_param *arg)
{
	return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_HEAD_ID);
}

static bool is_kfunc_arg_list_node(const struct btf *btf, const struct btf_param *arg)
{
	return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_LIST_NODE_ID);
}

static bool is_kfunc_arg_rbtree_root(const struct btf *btf, const struct btf_param *arg)
{
	return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_ROOT_ID);
}

static bool is_kfunc_arg_rbtree_node(const struct btf *btf, const struct btf_param *arg)
{
	return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_NODE_ID);
}

static bool is_kfunc_arg_wq(const struct btf *btf, const struct btf_param *arg)
{
	return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_WORKQUEUE_ID);
}

static bool is_kfunc_arg_callback(struct bpf_verifier_env *env, const struct btf *btf,
				  const struct btf_param *arg)
{
	const struct btf_type *t;

	t = btf_type_resolve_func_ptr(btf, arg->type, NULL);
	if (!t)
		return false;

	return true;
}

/* Returns true if struct is composed of scalars, 4 levels of nesting allowed */
static bool __btf_type_is_scalar_struct(struct bpf_verifier_env *env,
					const struct btf *btf,
					const struct btf_type *t, int rec)
{
	const struct btf_type *member_type;
	const struct btf_member *member;
	u32 i;

	if (!btf_type_is_struct(t))
		return false;

	for_each_member(i, t, member) {
		const struct btf_array *array;

		member_type = btf_type_skip_modifiers(btf, member->type, NULL);
		if (btf_type_is_struct(member_type)) {
			if (rec >= 3) {
				verbose(env, "max struct nesting depth exceeded\n");
				return false;
			}
			if (!__btf_type_is_scalar_struct(env, btf, member_type, rec + 1))
				return false;
			continue;
		}
		if (btf_type_is_array(member_type)) {
			array = btf_array(member_type);
			if (!array->nelems)
				return false;
			member_type = btf_type_skip_modifiers(btf, array->type, NULL);
			if (!btf_type_is_scalar(member_type))
				return false;
			continue;
		}
		if (!btf_type_is_scalar(member_type))
			return false;
	}
	return true;
}

enum kfunc_ptr_arg_type {
	KF_ARG_PTR_TO_CTX,
	KF_ARG_PTR_TO_ALLOC_BTF_ID,    /* Allocated object */
	KF_ARG_PTR_TO_REFCOUNTED_KPTR, /* Refcounted local kptr */
	KF_ARG_PTR_TO_DYNPTR,
	KF_ARG_PTR_TO_ITER,
	KF_ARG_PTR_TO_LIST_HEAD,
	KF_ARG_PTR_TO_LIST_NODE,
	KF_ARG_PTR_TO_BTF_ID,	       /* Also covers reg2btf_ids conversions */
	KF_ARG_PTR_TO_MEM,
	KF_ARG_PTR_TO_MEM_SIZE,	       /* Size derived from next argument, skip it */
	KF_ARG_PTR_TO_CALLBACK,
	KF_ARG_PTR_TO_RB_ROOT,
	KF_ARG_PTR_TO_RB_NODE,
	KF_ARG_PTR_TO_NULL,
	KF_ARG_PTR_TO_CONST_STR,
	KF_ARG_PTR_TO_MAP,
	KF_ARG_PTR_TO_WORKQUEUE,
};

enum special_kfunc_type {
	KF_bpf_obj_new_impl,
	KF_bpf_obj_drop_impl,
	KF_bpf_refcount_acquire_impl,
	KF_bpf_list_push_front_impl,
	KF_bpf_list_push_back_impl,
	KF_bpf_list_pop_front,
	KF_bpf_list_pop_back,
	KF_bpf_cast_to_kern_ctx,
	KF_bpf_rdonly_cast,
	KF_bpf_rcu_read_lock,
	KF_bpf_rcu_read_unlock,
	KF_bpf_rbtree_remove,
	KF_bpf_rbtree_add_impl,
	KF_bpf_rbtree_first,
	KF_bpf_dynptr_from_skb,
	KF_bpf_dynptr_from_xdp,
	KF_bpf_dynptr_slice,
	KF_bpf_dynptr_slice_rdwr,
	KF_bpf_dynptr_clone,
	KF_bpf_percpu_obj_new_impl,
	KF_bpf_percpu_obj_drop_impl,
	KF_bpf_throw,
	KF_bpf_wq_set_callback_impl,
	KF_bpf_preempt_disable,
	KF_bpf_preempt_enable,
	KF_bpf_iter_css_task_new,
	KF_bpf_session_cookie,
};

BTF_SET_START(special_kfunc_set)
BTF_ID(func, bpf_obj_new_impl)
BTF_ID(func, bpf_obj_drop_impl)
BTF_ID(func, bpf_refcount_acquire_impl)
BTF_ID(func, bpf_list_push_front_impl)
BTF_ID(func, bpf_list_push_back_impl)
BTF_ID(func, bpf_list_pop_front)
BTF_ID(func, bpf_list_pop_back)
BTF_ID(func, bpf_cast_to_kern_ctx)
BTF_ID(func, bpf_rdonly_cast)
BTF_ID(func, bpf_rbtree_remove)
BTF_ID(func, bpf_rbtree_add_impl)
BTF_ID(func, bpf_rbtree_first)
BTF_ID(func, bpf_dynptr_from_skb)
BTF_ID(func, bpf_dynptr_from_xdp)
BTF_ID(func, bpf_dynptr_slice)
BTF_ID(func, bpf_dynptr_slice_rdwr)
BTF_ID(func, bpf_dynptr_clone)
BTF_ID(func, bpf_percpu_obj_new_impl)
BTF_ID(func, bpf_percpu_obj_drop_impl)
BTF_ID(func, bpf_throw)
BTF_ID(func, bpf_wq_set_callback_impl)
#ifdef CONFIG_CGROUPS
BTF_ID(func, bpf_iter_css_task_new)
#endif
BTF_SET_END(special_kfunc_set)

BTF_ID_LIST(special_kfunc_list)
BTF_ID(func, bpf_obj_new_impl)
BTF_ID(func, bpf_obj_drop_impl)
BTF_ID(func, bpf_refcount_acquire_impl)
BTF_ID(func, bpf_list_push_front_impl)
BTF_ID(func, bpf_list_push_back_impl)
BTF_ID(func, bpf_list_pop_front)
BTF_ID(func, bpf_list_pop_back)
BTF_ID(func, bpf_cast_to_kern_ctx)
BTF_ID(func, bpf_rdonly_cast)
BTF_ID(func, bpf_rcu_read_lock)
BTF_ID(func, bpf_rcu_read_unlock)
BTF_ID(func, bpf_rbtree_remove)
BTF_ID(func, bpf_rbtree_add_impl)
BTF_ID(func, bpf_rbtree_first)
BTF_ID(func, bpf_dynptr_from_skb)
BTF_ID(func, bpf_dynptr_from_xdp)
BTF_ID(func, bpf_dynptr_slice)
BTF_ID(func, bpf_dynptr_slice_rdwr)
BTF_ID(func, bpf_dynptr_clone)
BTF_ID(func, bpf_percpu_obj_new_impl)
BTF_ID(func, bpf_percpu_obj_drop_impl)
BTF_ID(func, bpf_throw)
BTF_ID(func, bpf_wq_set_callback_impl)
BTF_ID(func, bpf_preempt_disable)
BTF_ID(func, bpf_preempt_enable)
#ifdef CONFIG_CGROUPS
BTF_ID(func, bpf_iter_css_task_new)
#else
BTF_ID_UNUSED
#endif
#ifdef CONFIG_BPF_EVENTS
BTF_ID(func, bpf_session_cookie)
#else
BTF_ID_UNUSED
#endif

static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta)
{
	if (meta->func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl] &&
	    meta->arg_owning_ref) {
		return false;
	}

	return meta->kfunc_flags & KF_RET_NULL;
}

static bool is_kfunc_bpf_rcu_read_lock(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_lock];
}

static bool is_kfunc_bpf_rcu_read_unlock(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->func_id == special_kfunc_list[KF_bpf_rcu_read_unlock];
}

static bool is_kfunc_bpf_preempt_disable(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->func_id == special_kfunc_list[KF_bpf_preempt_disable];
}

static bool is_kfunc_bpf_preempt_enable(struct bpf_kfunc_call_arg_meta *meta)
{
	return meta->func_id == special_kfunc_list[KF_bpf_preempt_enable];
}

static enum kfunc_ptr_arg_type
get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
		       struct bpf_kfunc_call_arg_meta *meta,
		       const struct btf_type *t, const struct btf_type *ref_t,
		       const char *ref_tname, const struct btf_param *args,
		       int argno, int nargs)
{
	u32 regno = argno + 1;
	struct bpf_reg_state *regs = cur_regs(env);
	struct bpf_reg_state *reg = &regs[regno];
	bool arg_mem_size = false;

	if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx])
		return KF_ARG_PTR_TO_CTX;

	/* In this function, we verify the kfunc's BTF as per the argument type,
	 * leaving the rest of the verification with respect to the register
	 * type to our caller. When a set of conditions hold in the BTF type of
	 * arguments, we resolve it to a known kfunc_ptr_arg_type.
	 */
	if (btf_is_prog_ctx_type(&env->log, meta->btf, t, resolve_prog_type(env->prog), argno))
		return KF_ARG_PTR_TO_CTX;

	if (is_kfunc_arg_nullable(meta->btf, &args[argno]) && register_is_null(reg))
		return KF_ARG_PTR_TO_NULL;

	if (is_kfunc_arg_alloc_obj(meta->btf, &args[argno]))
		return KF_ARG_PTR_TO_ALLOC_BTF_ID;

	if (is_kfunc_arg_refcounted_kptr(meta->btf, &args[argno]))
		return KF_ARG_PTR_TO_REFCOUNTED_KPTR;

	if (is_kfunc_arg_dynptr(meta->btf, &args[argno]))
		return KF_ARG_PTR_TO_DYNPTR;

	if (is_kfunc_arg_iter(meta, argno, &args[argno]))
		return KF_ARG_PTR_TO_ITER;

	if (is_kfunc_arg_list_head(meta->btf, &args[argno]))
		return KF_ARG_PTR_TO_LIST_HEAD;

	if (is_kfunc_arg_list_node(meta->btf, &args[argno]))
		return KF_ARG_PTR_TO_LIST_NODE;

	if (is_kfunc_arg_rbtree_root(meta->btf, &args[argno]))
		return KF_ARG_PTR_TO_RB_ROOT;

	if (is_kfunc_arg_rbtree_node(meta->btf, &args[argno]))
		return KF_ARG_PTR_TO_RB_NODE;

	if (is_kfunc_arg_const_str(meta->btf, &args[argno]))
		return KF_ARG_PTR_TO_CONST_STR;

	if (is_kfunc_arg_map(meta->btf, &args[argno]))
		return KF_ARG_PTR_TO_MAP;

	if (is_kfunc_arg_wq(meta->btf, &args[argno]))
		return KF_ARG_PTR_TO_WORKQUEUE;

	if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) {
		if (!btf_type_is_struct(ref_t)) {
			verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n",
				meta->func_name, argno, btf_type_str(ref_t), ref_tname);
			return -EINVAL;
		}
		return KF_ARG_PTR_TO_BTF_ID;
	}

	if (is_kfunc_arg_callback(env, meta->btf, &args[argno]))
		return KF_ARG_PTR_TO_CALLBACK;

	if (argno + 1 < nargs &&
	    (is_kfunc_arg_mem_size(meta->btf, &args[argno + 1], &regs[regno + 1]) ||
	     is_kfunc_arg_const_mem_size(meta->btf, &args[argno + 1], &regs[regno + 1])))
		arg_mem_size = true;

	/* This is the catch all argument type of register types supported by
	 * check_helper_mem_access. However, we only allow when argument type is
	 * pointer to scalar, or struct composed (recursively) of scalars. When
	 * arg_mem_size is true, the pointer can be void *.
	 */
	if (!btf_type_is_scalar(ref_t) && !__btf_type_is_scalar_struct(env, meta->btf, ref_t, 0) &&
	    (arg_mem_size ? !btf_type_is_void(ref_t) : 1)) {
		verbose(env, "arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n",
			argno, btf_type_str(ref_t), ref_tname, arg_mem_size ? "void, " : "");
		return -EINVAL;
	}
	return arg_mem_size ? KF_ARG_PTR_TO_MEM_SIZE : KF_ARG_PTR_TO_MEM;
}

static int process_kf_arg_ptr_to_btf_id(struct bpf_verifier_env *env,
					struct bpf_reg_state *reg,
					const struct btf_type *ref_t,
					const char *ref_tname, u32 ref_id,
					struct bpf_kfunc_call_arg_meta *meta,
					int argno)
{
	const struct btf_type *reg_ref_t;
	bool strict_type_match = false;
	const struct btf *reg_btf;
	const char *reg_ref_tname;
	bool taking_projection;
	bool struct_same;
	u32 reg_ref_id;

	if (base_type(reg->type) == PTR_TO_BTF_ID) {
		reg_btf = reg->btf;
		reg_ref_id = reg->btf_id;
	} else {
		reg_btf = btf_vmlinux;
		reg_ref_id = *reg2btf_ids[base_type(reg->type)];
	}

	/* Enforce strict type matching for calls to kfuncs that are acquiring
	 * or releasing a reference, or are no-cast aliases. We do _not_
	 * enforce strict matching for plain KF_TRUSTED_ARGS kfuncs by default,
	 * as we want to enable BPF programs to pass types that are bitwise
	 * equivalent without forcing them to explicitly cast with something
	 * like bpf_cast_to_kern_ctx().
	 *
	 * For example, say we had a type like the following:
	 *
	 * struct bpf_cpumask {
	 *	cpumask_t cpumask;
	 *	refcount_t usage;
	 * };
	 *
	 * Note that as specified in <linux/cpumask.h>, cpumask_t is typedef'ed
	 * to a struct cpumask, so it would be safe to pass a struct
	 * bpf_cpumask * to a kfunc expecting a struct cpumask *.
	 *
	 * The philosophy here is similar to how we allow scalars of different
	 * types to be passed to kfuncs as long as the size is the same. The
	 * only difference here is that we're simply allowing
	 * btf_struct_ids_match() to walk the struct at the 0th offset, and
	 * resolve types.
	 */
	if ((is_kfunc_release(meta) && reg->ref_obj_id) ||
	    btf_type_ids_nocast_alias(&env->log, reg_btf, reg_ref_id, meta->btf, ref_id))
		strict_type_match = true;

	WARN_ON_ONCE(is_kfunc_release(meta) &&
		     (reg->off || !tnum_is_const(reg->var_off) ||
		      reg->var_off.value));

	reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id, &reg_ref_id);
	reg_ref_tname = btf_name_by_offset(reg_btf, reg_ref_t->name_off);
	struct_same = btf_struct_ids_match(&env->log, reg_btf, reg_ref_id, reg->off, meta->btf, ref_id, strict_type_match);
	/* If kfunc is accepting a projection type (ie. __sk_buff), it cannot
	 * actually use it -- it must cast to the underlying type. So we allow
	 * caller to pass in the underlying type.
	 */
	taking_projection = btf_is_projection_of(ref_tname, reg_ref_tname);
	if (!taking_projection && !struct_same) {
		verbose(env, "kernel function %s args#%d expected pointer to %s %s but R%d has a pointer to %s %s\n",
			meta->func_name, argno, btf_type_str(ref_t), ref_tname, argno + 1,
			btf_type_str(reg_ref_t), reg_ref_tname);
		return -EINVAL;
	}
	return 0;
}

static int ref_set_non_owning(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
	struct bpf_verifier_state *state = env->cur_state;
	struct btf_record *rec = reg_btf_record(reg);

	if (!state->active_lock.ptr) {
		verbose(env, "verifier internal error: ref_set_non_owning w/o active lock\n");
		return -EFAULT;
	}

	if (type_flag(reg->type) & NON_OWN_REF) {
		verbose(env, "verifier internal error: NON_OWN_REF already set\n");
		return -EFAULT;
	}

	reg->type |= NON_OWN_REF;
	if (rec->refcount_off >= 0)
		reg->type |= MEM_RCU;

	return 0;
}

static int ref_convert_owning_non_owning(struct bpf_verifier_env *env, u32 ref_obj_id)
{
	struct bpf_func_state *state, *unused;
	struct bpf_reg_state *reg;
	int i;

	state = cur_func(env);

	if (!ref_obj_id) {
		verbose(env, "verifier internal error: ref_obj_id is zero for "
			     "owning -> non-owning conversion\n");
		return -EFAULT;
	}

	for (i = 0; i < state->acquired_refs; i++) {
		if (state->refs[i].id != ref_obj_id)
			continue;

		/* Clear ref_obj_id here so release_reference doesn't clobber
		 * the whole reg
		 */
		bpf_for_each_reg_in_vstate(env->cur_state, unused, reg, ({
			if (reg->ref_obj_id == ref_obj_id) {
				reg->ref_obj_id = 0;
				ref_set_non_owning(env, reg);
			}
		}));
		return 0;
	}

	verbose(env, "verifier internal error: ref state missing for ref_obj_id\n");
	return -EFAULT;
}

/* Implementation details:
 *
 * Each register points to some region of memory, which we define as an
 * allocation. Each allocation may embed a bpf_spin_lock which protects any
 * special BPF objects (bpf_list_head, bpf_rb_root, etc.) part of the same
 * allocation. The lock and the data it protects are colocated in the same
 * memory region.
 *
 * Hence, everytime a register holds a pointer value pointing to such
 * allocation, the verifier preserves a unique reg->id for it.
 *
 * The verifier remembers the lock 'ptr' and the lock 'id' whenever
 * bpf_spin_lock is called.
 *
 * To enable this, lock state in the verifier captures two values:
 *	active_lock.ptr = Register's type specific pointer
 *	active_lock.id  = A unique ID for each register pointer value
 *
 * Currently, PTR_TO_MAP_VALUE and PTR_TO_BTF_ID | MEM_ALLOC are the two
 * supported register types.
 *
 * The active_lock.ptr in case of map values is the reg->map_ptr, and in case of
 * allocated objects is the reg->btf pointer.
 *
 * The active_lock.id is non-unique for maps supporting direct_value_addr, as we
 * can establish the provenance of the map value statically for each distinct
 * lookup into such maps. They always contain a single map value hence unique
 * IDs for each pseudo load pessimizes the algorithm and rejects valid programs.
 *
 * So, in case of global variables, they use array maps with max_entries = 1,
 * hence their active_lock.ptr becomes map_ptr and id = 0 (since they all point
 * into the same map value as max_entries is 1, as described above).
 *
 * In case of inner map lookups, the inner map pointer has same map_ptr as the
 * outer map pointer (in verifier context), but each lookup into an inner map
 * assigns a fresh reg->id to the lookup, so while lookups into distinct inner
 * maps from the same outer map share the same map_ptr as active_lock.ptr, they
 * will get different reg->id assigned to each lookup, hence different
 * active_lock.id.
 *
 * In case of allocated objects, active_lock.ptr is the reg->btf, and the
 * reg->id is a unique ID preserved after the NULL pointer check on the pointer
 * returned from bpf_obj_new. Each allocation receives a new reg->id.
 */
static int check_reg_allocation_locked(struct bpf_verifier_env *env, struct bpf_reg_state *reg)
{
	void *ptr;
	u32 id;

	switch ((int)reg->type) {
	case PTR_TO_MAP_VALUE:
		ptr = reg->map_ptr;
		break;
	case PTR_TO_BTF_ID | MEM_ALLOC:
		ptr = reg->btf;
		break;
	default:
		verbose(env, "verifier internal error: unknown reg type for lock check\n");
		return -EFAULT;
	}
	id = reg->id;

	if (!env->cur_state->active_lock.ptr)
		return -EINVAL;
	if (env->cur_state->active_lock.ptr != ptr ||
	    env->cur_state->active_lock.id != id) {
		verbose(env, "held lock and object are not in the same allocation\n");
		return -EINVAL;
	}
	return 0;
}

static bool is_bpf_list_api_kfunc(u32 btf_id)
{
	return btf_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
	       btf_id == special_kfunc_list[KF_bpf_list_push_back_impl] ||
	       btf_id == special_kfunc_list[KF_bpf_list_pop_front] ||
	       btf_id == special_kfunc_list[KF_bpf_list_pop_back];
}

static bool is_bpf_rbtree_api_kfunc(u32 btf_id)
{
	return btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl] ||
	       btf_id == special_kfunc_list[KF_bpf_rbtree_remove] ||
	       btf_id == special_kfunc_list[KF_bpf_rbtree_first];
}

static bool is_bpf_graph_api_kfunc(u32 btf_id)
{
	return is_bpf_list_api_kfunc(btf_id) || is_bpf_rbtree_api_kfunc(btf_id) ||
	       btf_id == special_kfunc_list[KF_bpf_refcount_acquire_impl];
}

static bool is_sync_callback_calling_kfunc(u32 btf_id)
{
	return btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl];
}

static bool is_async_callback_calling_kfunc(u32 btf_id)
{
	return btf_id == special_kfunc_list[KF_bpf_wq_set_callback_impl];
}

static bool is_bpf_throw_kfunc(struct bpf_insn *insn)
{
	return bpf_pseudo_kfunc_call(insn) && insn->off == 0 &&
	       insn->imm == special_kfunc_list[KF_bpf_throw];
}

static bool is_bpf_wq_set_callback_impl_kfunc(u32 btf_id)
{
	return btf_id == special_kfunc_list[KF_bpf_wq_set_callback_impl];
}

static bool is_callback_calling_kfunc(u32 btf_id)
{
	return is_sync_callback_calling_kfunc(btf_id) ||
	       is_async_callback_calling_kfunc(btf_id);
}

static bool is_rbtree_lock_required_kfunc(u32 btf_id)
{
	return is_bpf_rbtree_api_kfunc(btf_id);
}

static bool check_kfunc_is_graph_root_api(struct bpf_verifier_env *env,
					  enum btf_field_type head_field_type,
					  u32 kfunc_btf_id)
{
	bool ret;

	switch (head_field_type) {
	case BPF_LIST_HEAD:
		ret = is_bpf_list_api_kfunc(kfunc_btf_id);
		break;
	case BPF_RB_ROOT:
		ret = is_bpf_rbtree_api_kfunc(kfunc_btf_id);
		break;
	default:
		verbose(env, "verifier internal error: unexpected graph root argument type %s\n",
			btf_field_type_name(head_field_type));
		return false;
	}

	if (!ret)
		verbose(env, "verifier internal error: %s head arg for unknown kfunc\n",
			btf_field_type_name(head_field_type));
	return ret;
}

static bool check_kfunc_is_graph_node_api(struct bpf_verifier_env *env,
					  enum btf_field_type node_field_type,
					  u32 kfunc_btf_id)
{
	bool ret;

	switch (node_field_type) {
	case BPF_LIST_NODE:
		ret = (kfunc_btf_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
		       kfunc_btf_id == special_kfunc_list[KF_bpf_list_push_back_impl]);
		break;
	case BPF_RB_NODE:
		ret = (kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_remove] ||
		       kfunc_btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl]);
		break;
	default:
		verbose(env, "verifier internal error: unexpected graph node argument type %s\n",
			btf_field_type_name(node_field_type));
		return false;
	}

	if (!ret)
		verbose(env, "verifier internal error: %s node arg for unknown kfunc\n",
			btf_field_type_name(node_field_type));
	return ret;
}

static int
__process_kf_arg_ptr_to_graph_root(struct bpf_verifier_env *env,
				   struct bpf_reg_state *reg, u32 regno,
				   struct bpf_kfunc_call_arg_meta *meta,
				   enum btf_field_type head_field_type,
				   struct btf_field **head_field)
{
	const char *head_type_name;
	struct btf_field *field;
	struct btf_record *rec;
	u32 head_off;

	if (meta->btf != btf_vmlinux) {
		verbose(env, "verifier internal error: unexpected btf mismatch in kfunc call\n");
		return -EFAULT;
	}

	if (!check_kfunc_is_graph_root_api(env, head_field_type, meta->func_id))
		return -EFAULT;

	head_type_name = btf_field_type_name(head_field_type);
	if (!tnum_is_const(reg->var_off)) {
		verbose(env,
			"R%d doesn't have constant offset. %s has to be at the constant offset\n",
			regno, head_type_name);
		return -EINVAL;
	}

	rec = reg_btf_record(reg);
	head_off = reg->off + reg->var_off.value;
	field = btf_record_find(rec, head_off, head_field_type);
	if (!field) {
		verbose(env, "%s not found at offset=%u\n", head_type_name, head_off);
		return -EINVAL;
	}

	/* All functions require bpf_list_head to be protected using a bpf_spin_lock */
	if (check_reg_allocation_locked(env, reg)) {
		verbose(env, "bpf_spin_lock at off=%d must be held for %s\n",
			rec->spin_lock_off, head_type_name);
		return -EINVAL;
	}

	if (*head_field) {
		verbose(env, "verifier internal error: repeating %s arg\n", head_type_name);
		return -EFAULT;
	}
	*head_field = field;
	return 0;
}

static int process_kf_arg_ptr_to_list_head(struct bpf_verifier_env *env,
					   struct bpf_reg_state *reg, u32 regno,
					   struct bpf_kfunc_call_arg_meta *meta)
{
	return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_LIST_HEAD,
							  &meta->arg_list_head.field);
}

static int process_kf_arg_ptr_to_rbtree_root(struct bpf_verifier_env *env,
					     struct bpf_reg_state *reg, u32 regno,
					     struct bpf_kfunc_call_arg_meta *meta)
{
	return __process_kf_arg_ptr_to_graph_root(env, reg, regno, meta, BPF_RB_ROOT,
							  &meta->arg_rbtree_root.field);
}

static int
__process_kf_arg_ptr_to_graph_node(struct bpf_verifier_env *env,
				   struct bpf_reg_state *reg, u32 regno,
				   struct bpf_kfunc_call_arg_meta *meta,
				   enum btf_field_type head_field_type,
				   enum btf_field_type node_field_type,
				   struct btf_field **node_field)
{
	const char *node_type_name;
	const struct btf_type *et, *t;
	struct btf_field *field;
	u32 node_off;

	if (meta->btf != btf_vmlinux) {
		verbose(env, "verifier internal error: unexpected btf mismatch in kfunc call\n");
		return -EFAULT;
	}

	if (!check_kfunc_is_graph_node_api(env, node_field_type, meta->func_id))
		return -EFAULT;

	node_type_name = btf_field_type_name(node_field_type);
	if (!tnum_is_const(reg->var_off)) {
		verbose(env,
			"R%d doesn't have constant offset. %s has to be at the constant offset\n",
			regno, node_type_name);
		return -EINVAL;
	}

	node_off = reg->off + reg->var_off.value;
	field = reg_find_field_offset(reg, node_off, node_field_type);
	if (!field) {
		verbose(env, "%s not found at offset=%u\n", node_type_name, node_off);
		return -EINVAL;
	}

	field = *node_field;

	et = btf_type_by_id(field->graph_root.btf, field->graph_root.value_btf_id);
	t = btf_type_by_id(reg->btf, reg->btf_id);
	if (!btf_struct_ids_match(&env->log, reg->btf, reg->btf_id, 0, field->graph_root.btf,
				  field->graph_root.value_btf_id, true)) {
		verbose(env, "operation on %s expects arg#1 %s at offset=%d "
			"in struct %s, but arg is at offset=%d in struct %s\n",
			btf_field_type_name(head_field_type),
			btf_field_type_name(node_field_type),
			field->graph_root.node_offset,
			btf_name_by_offset(field->graph_root.btf, et->name_off),
			node_off, btf_name_by_offset(reg->btf, t->name_off));
		return -EINVAL;
	}
	meta->arg_btf = reg->btf;
	meta->arg_btf_id = reg->btf_id;

	if (node_off != field->graph_root.node_offset) {
		verbose(env, "arg#1 offset=%d, but expected %s at offset=%d in struct %s\n",
			node_off, btf_field_type_name(node_field_type),
			field->graph_root.node_offset,
			btf_name_by_offset(field->graph_root.btf, et->name_off));
		return -EINVAL;
	}

	return 0;
}

static int process_kf_arg_ptr_to_list_node(struct bpf_verifier_env *env,
					   struct bpf_reg_state *reg, u32 regno,
					   struct bpf_kfunc_call_arg_meta *meta)
{
	return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta,
						  BPF_LIST_HEAD, BPF_LIST_NODE,
						  &meta->arg_list_head.field);
}

static int process_kf_arg_ptr_to_rbtree_node(struct bpf_verifier_env *env,
					     struct bpf_reg_state *reg, u32 regno,
					     struct bpf_kfunc_call_arg_meta *meta)
{
	return __process_kf_arg_ptr_to_graph_node(env, reg, regno, meta,
						  BPF_RB_ROOT, BPF_RB_NODE,
						  &meta->arg_rbtree_root.field);
}

/*
 * css_task iter allowlist is needed to avoid dead locking on css_set_lock.
 * LSM hooks and iters (both sleepable and non-sleepable) are safe.
 * Any sleepable progs are also safe since bpf_check_attach_target() enforce
 * them can only be attached to some specific hook points.
 */
static bool check_css_task_iter_allowlist(struct bpf_verifier_env *env)
{
	enum bpf_prog_type prog_type = resolve_prog_type(env->prog);

	switch (prog_type) {
	case BPF_PROG_TYPE_LSM:
		return true;
	case BPF_PROG_TYPE_TRACING:
		if (env->prog->expected_attach_type == BPF_TRACE_ITER)
			return true;
		fallthrough;
	default:
		return in_sleepable(env);
	}
}

static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta,
			    int insn_idx)
{
	const char *func_name = meta->func_name, *ref_tname;
	const struct btf *btf = meta->btf;
	const struct btf_param *args;
	struct btf_record *rec;
	u32 i, nargs;
	int ret;

	args = (const struct btf_param *)(meta->func_proto + 1);
	nargs = btf_type_vlen(meta->func_proto);
	if (nargs > MAX_BPF_FUNC_REG_ARGS) {
		verbose(env, "Function %s has %d > %d args\n", func_name, nargs,
			MAX_BPF_FUNC_REG_ARGS);
		return -EINVAL;
	}

	/* Check that BTF function arguments match actual types that the
	 * verifier sees.
	 */
	for (i = 0; i < nargs; i++) {
		struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[i + 1];
		const struct btf_type *t, *ref_t, *resolve_ret;
		enum bpf_arg_type arg_type = ARG_DONTCARE;
		u32 regno = i + 1, ref_id, type_size;
		bool is_ret_buf_sz = false;
		int kf_arg_type;

		t = btf_type_skip_modifiers(btf, args[i].type, NULL);

		if (is_kfunc_arg_ignore(btf, &args[i]))
			continue;

		if (btf_type_is_scalar(t)) {
			if (reg->type != SCALAR_VALUE) {
				verbose(env, "R%d is not a scalar\n", regno);
				return -EINVAL;
			}

			if (is_kfunc_arg_constant(meta->btf, &args[i])) {
				if (meta->arg_constant.found) {
					verbose(env, "verifier internal error: only one constant argument permitted\n");
					return -EFAULT;
				}
				if (!tnum_is_const(reg->var_off)) {
					verbose(env, "R%d must be a known constant\n", regno);
					return -EINVAL;
				}
				ret = mark_chain_precision(env, regno);
				if (ret < 0)
					return ret;
				meta->arg_constant.found = true;
				meta->arg_constant.value = reg->var_off.value;
			} else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdonly_buf_size")) {
				meta->r0_rdonly = true;
				is_ret_buf_sz = true;
			} else if (is_kfunc_arg_scalar_with_name(btf, &args[i], "rdwr_buf_size")) {
				is_ret_buf_sz = true;
			}

			if (is_ret_buf_sz) {
				if (meta->r0_size) {
					verbose(env, "2 or more rdonly/rdwr_buf_size parameters for kfunc");
					return -EINVAL;
				}

				if (!tnum_is_const(reg->var_off)) {
					verbose(env, "R%d is not a const\n", regno);
					return -EINVAL;
				}

				meta->r0_size = reg->var_off.value;
				ret = mark_chain_precision(env, regno);
				if (ret)
					return ret;
			}
			continue;
		}

		if (!btf_type_is_ptr(t)) {
			verbose(env, "Unrecognized arg#%d type %s\n", i, btf_type_str(t));
			return -EINVAL;
		}

		if ((is_kfunc_trusted_args(meta) || is_kfunc_rcu(meta)) &&
		    (register_is_null(reg) || type_may_be_null(reg->type)) &&
			!is_kfunc_arg_nullable(meta->btf, &args[i])) {
			verbose(env, "Possibly NULL pointer passed to trusted arg%d\n", i);
			return -EACCES;
		}

		if (reg->ref_obj_id) {
			if (is_kfunc_release(meta) && meta->ref_obj_id) {
				verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
					regno, reg->ref_obj_id,
					meta->ref_obj_id);
				return -EFAULT;
			}
			meta->ref_obj_id = reg->ref_obj_id;
			if (is_kfunc_release(meta))
				meta->release_regno = regno;
		}

		ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
		ref_tname = btf_name_by_offset(btf, ref_t->name_off);

		kf_arg_type = get_kfunc_ptr_arg_type(env, meta, t, ref_t, ref_tname, args, i, nargs);
		if (kf_arg_type < 0)
			return kf_arg_type;

		switch (kf_arg_type) {
		case KF_ARG_PTR_TO_NULL:
			continue;
		case KF_ARG_PTR_TO_MAP:
			if (!reg->map_ptr) {
				verbose(env, "pointer in R%d isn't map pointer\n", regno);
				return -EINVAL;
			}
			if (meta->map.ptr && reg->map_ptr->record->wq_off >= 0) {
				/* Use map_uid (which is unique id of inner map) to reject:
				 * inner_map1 = bpf_map_lookup_elem(outer_map, key1)
				 * inner_map2 = bpf_map_lookup_elem(outer_map, key2)
				 * if (inner_map1 && inner_map2) {
				 *     wq = bpf_map_lookup_elem(inner_map1);
				 *     if (wq)
				 *         // mismatch would have been allowed
				 *         bpf_wq_init(wq, inner_map2);
				 * }
				 *
				 * Comparing map_ptr is enough to distinguish normal and outer maps.
				 */
				if (meta->map.ptr != reg->map_ptr ||
				    meta->map.uid != reg->map_uid) {
					verbose(env,
						"workqueue pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n",
						meta->map.uid, reg->map_uid);
					return -EINVAL;
				}
			}
			meta->map.ptr = reg->map_ptr;
			meta->map.uid = reg->map_uid;
			fallthrough;
		case KF_ARG_PTR_TO_ALLOC_BTF_ID:
		case KF_ARG_PTR_TO_BTF_ID:
			if (!is_kfunc_trusted_args(meta) && !is_kfunc_rcu(meta))
				break;

			if (!is_trusted_reg(reg)) {
				if (!is_kfunc_rcu(meta)) {
					verbose(env, "R%d must be referenced or trusted\n", regno);
					return -EINVAL;
				}
				if (!is_rcu_reg(reg)) {
					verbose(env, "R%d must be a rcu pointer\n", regno);
					return -EINVAL;
				}
			}
			fallthrough;
		case KF_ARG_PTR_TO_CTX:
		case KF_ARG_PTR_TO_DYNPTR:
		case KF_ARG_PTR_TO_ITER:
		case KF_ARG_PTR_TO_LIST_HEAD:
		case KF_ARG_PTR_TO_LIST_NODE:
		case KF_ARG_PTR_TO_RB_ROOT:
		case KF_ARG_PTR_TO_RB_NODE:
		case KF_ARG_PTR_TO_MEM:
		case KF_ARG_PTR_TO_MEM_SIZE:
		case KF_ARG_PTR_TO_CALLBACK:
		case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
		case KF_ARG_PTR_TO_CONST_STR:
		case KF_ARG_PTR_TO_WORKQUEUE:
			break;
		default:
			WARN_ON_ONCE(1);
			return -EFAULT;
		}

		if (is_kfunc_release(meta) && reg->ref_obj_id)
			arg_type |= OBJ_RELEASE;
		ret = check_func_arg_reg_off(env, reg, regno, arg_type);
		if (ret < 0)
			return ret;

		switch (kf_arg_type) {
		case KF_ARG_PTR_TO_CTX:
			if (reg->type != PTR_TO_CTX) {
				verbose(env, "arg#%d expected pointer to ctx, but got %s\n",
					i, reg_type_str(env, reg->type));
				return -EINVAL;
			}

			if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) {
				ret = get_kern_ctx_btf_id(&env->log, resolve_prog_type(env->prog));
				if (ret < 0)
					return -EINVAL;
				meta->ret_btf_id  = ret;
			}
			break;
		case KF_ARG_PTR_TO_ALLOC_BTF_ID:
			if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC)) {
				if (meta->func_id != special_kfunc_list[KF_bpf_obj_drop_impl]) {
					verbose(env, "arg#%d expected for bpf_obj_drop_impl()\n", i);
					return -EINVAL;
				}
			} else if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC | MEM_PERCPU)) {
				if (meta->func_id != special_kfunc_list[KF_bpf_percpu_obj_drop_impl]) {
					verbose(env, "arg#%d expected for bpf_percpu_obj_drop_impl()\n", i);
					return -EINVAL;
				}
			} else {
				verbose(env, "arg#%d expected pointer to allocated object\n", i);
				return -EINVAL;
			}
			if (!reg->ref_obj_id) {
				verbose(env, "allocated object must be referenced\n");
				return -EINVAL;
			}
			if (meta->btf == btf_vmlinux) {
				meta->arg_btf = reg->btf;
				meta->arg_btf_id = reg->btf_id;
			}
			break;
		case KF_ARG_PTR_TO_DYNPTR:
		{
			enum bpf_arg_type dynptr_arg_type = ARG_PTR_TO_DYNPTR;
			int clone_ref_obj_id = 0;

			if (reg->type == CONST_PTR_TO_DYNPTR)
				dynptr_arg_type |= MEM_RDONLY;

			if (is_kfunc_arg_uninit(btf, &args[i]))
				dynptr_arg_type |= MEM_UNINIT;

			if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_skb]) {
				dynptr_arg_type |= DYNPTR_TYPE_SKB;
			} else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_from_xdp]) {
				dynptr_arg_type |= DYNPTR_TYPE_XDP;
			} else if (meta->func_id == special_kfunc_list[KF_bpf_dynptr_clone] &&
				   (dynptr_arg_type & MEM_UNINIT)) {
				enum bpf_dynptr_type parent_type = meta->initialized_dynptr.type;

				if (parent_type == BPF_DYNPTR_TYPE_INVALID) {
					verbose(env, "verifier internal error: no dynptr type for parent of clone\n");
					return -EFAULT;
				}

				dynptr_arg_type |= (unsigned int)get_dynptr_type_flag(parent_type);
				clone_ref_obj_id = meta->initialized_dynptr.ref_obj_id;
				if (dynptr_type_refcounted(parent_type) && !clone_ref_obj_id) {
					verbose(env, "verifier internal error: missing ref obj id for parent of clone\n");
					return -EFAULT;
				}
			}

			ret = process_dynptr_func(env, regno, insn_idx, dynptr_arg_type, clone_ref_obj_id);
			if (ret < 0)
				return ret;

			if (!(dynptr_arg_type & MEM_UNINIT)) {
				int id = dynptr_id(env, reg);

				if (id < 0) {
					verbose(env, "verifier internal error: failed to obtain dynptr id\n");
					return id;
				}
				meta->initialized_dynptr.id = id;
				meta->initialized_dynptr.type = dynptr_get_type(env, reg);
				meta->initialized_dynptr.ref_obj_id = dynptr_ref_obj_id(env, reg);
			}

			break;
		}
		case KF_ARG_PTR_TO_ITER:
			if (meta->func_id == special_kfunc_list[KF_bpf_iter_css_task_new]) {
				if (!check_css_task_iter_allowlist(env)) {
					verbose(env, "css_task_iter is only allowed in bpf_lsm, bpf_iter and sleepable progs\n");
					return -EINVAL;
				}
			}
			ret = process_iter_arg(env, regno, insn_idx, meta);
			if (ret < 0)
				return ret;
			break;
		case KF_ARG_PTR_TO_LIST_HEAD:
			if (reg->type != PTR_TO_MAP_VALUE &&
			    reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
				verbose(env, "arg#%d expected pointer to map value or allocated object\n", i);
				return -EINVAL;
			}
			if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) {
				verbose(env, "allocated object must be referenced\n");
				return -EINVAL;
			}
			ret = process_kf_arg_ptr_to_list_head(env, reg, regno, meta);
			if (ret < 0)
				return ret;
			break;
		case KF_ARG_PTR_TO_RB_ROOT:
			if (reg->type != PTR_TO_MAP_VALUE &&
			    reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
				verbose(env, "arg#%d expected pointer to map value or allocated object\n", i);
				return -EINVAL;
			}
			if (reg->type == (PTR_TO_BTF_ID | MEM_ALLOC) && !reg->ref_obj_id) {
				verbose(env, "allocated object must be referenced\n");
				return -EINVAL;
			}
			ret = process_kf_arg_ptr_to_rbtree_root(env, reg, regno, meta);
			if (ret < 0)
				return ret;
			break;
		case KF_ARG_PTR_TO_LIST_NODE:
			if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
				verbose(env, "arg#%d expected pointer to allocated object\n", i);
				return -EINVAL;
			}
			if (!reg->ref_obj_id) {
				verbose(env, "allocated object must be referenced\n");
				return -EINVAL;
			}
			ret = process_kf_arg_ptr_to_list_node(env, reg, regno, meta);
			if (ret < 0)
				return ret;
			break;
		case KF_ARG_PTR_TO_RB_NODE:
			if (meta->func_id == special_kfunc_list[KF_bpf_rbtree_remove]) {
				if (!type_is_non_owning_ref(reg->type) || reg->ref_obj_id) {
					verbose(env, "rbtree_remove node input must be non-owning ref\n");
					return -EINVAL;
				}
				if (in_rbtree_lock_required_cb(env)) {
					verbose(env, "rbtree_remove not allowed in rbtree cb\n");
					return -EINVAL;
				}
			} else {
				if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC)) {
					verbose(env, "arg#%d expected pointer to allocated object\n", i);
					return -EINVAL;
				}
				if (!reg->ref_obj_id) {
					verbose(env, "allocated object must be referenced\n");
					return -EINVAL;
				}
			}

			ret = process_kf_arg_ptr_to_rbtree_node(env, reg, regno, meta);
			if (ret < 0)
				return ret;
			break;
		case KF_ARG_PTR_TO_MAP:
			/* If argument has '__map' suffix expect 'struct bpf_map *' */
			ref_id = *reg2btf_ids[CONST_PTR_TO_MAP];
			ref_t = btf_type_by_id(btf_vmlinux, ref_id);
			ref_tname = btf_name_by_offset(btf, ref_t->name_off);
			fallthrough;
		case KF_ARG_PTR_TO_BTF_ID:
			/* Only base_type is checked, further checks are done here */
			if ((base_type(reg->type) != PTR_TO_BTF_ID ||
			     (bpf_type_has_unsafe_modifiers(reg->type) && !is_rcu_reg(reg))) &&
			    !reg2btf_ids[base_type(reg->type)]) {
				verbose(env, "arg#%d is %s ", i, reg_type_str(env, reg->type));
				verbose(env, "expected %s or socket\n",
					reg_type_str(env, base_type(reg->type) |
							  (type_flag(reg->type) & BPF_REG_TRUSTED_MODIFIERS)));
				return -EINVAL;
			}
			ret = process_kf_arg_ptr_to_btf_id(env, reg, ref_t, ref_tname, ref_id, meta, i);
			if (ret < 0)
				return ret;
			break;
		case KF_ARG_PTR_TO_MEM:
			resolve_ret = btf_resolve_size(btf, ref_t, &type_size);
			if (IS_ERR(resolve_ret)) {
				verbose(env, "arg#%d reference type('%s %s') size cannot be determined: %ld\n",
					i, btf_type_str(ref_t), ref_tname, PTR_ERR(resolve_ret));
				return -EINVAL;
			}
			ret = check_mem_reg(env, reg, regno, type_size);
			if (ret < 0)
				return ret;
			break;
		case KF_ARG_PTR_TO_MEM_SIZE:
		{
			struct bpf_reg_state *buff_reg = &regs[regno];
			const struct btf_param *buff_arg = &args[i];
			struct bpf_reg_state *size_reg = &regs[regno + 1];
			const struct btf_param *size_arg = &args[i + 1];

			if (!register_is_null(buff_reg) || !is_kfunc_arg_optional(meta->btf, buff_arg)) {
				ret = check_kfunc_mem_size_reg(env, size_reg, regno + 1);
				if (ret < 0) {
					verbose(env, "arg#%d arg#%d memory, len pair leads to invalid memory access\n", i, i + 1);
					return ret;
				}
			}

			if (is_kfunc_arg_const_mem_size(meta->btf, size_arg, size_reg)) {
				if (meta->arg_constant.found) {
					verbose(env, "verifier internal error: only one constant argument permitted\n");
					return -EFAULT;
				}
				if (!tnum_is_const(size_reg->var_off)) {
					verbose(env, "R%d must be a known constant\n", regno + 1);
					return -EINVAL;
				}
				meta->arg_constant.found = true;
				meta->arg_constant.value = size_reg->var_off.value;
			}

			/* Skip next '__sz' or '__szk' argument */
			i++;
			break;
		}
		case KF_ARG_PTR_TO_CALLBACK:
			if (reg->type != PTR_TO_FUNC) {
				verbose(env, "arg%d expected pointer to func\n", i);
				return -EINVAL;
			}
			meta->subprogno = reg->subprogno;
			break;
		case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
			if (!type_is_ptr_alloc_obj(reg->type)) {
				verbose(env, "arg#%d is neither owning or non-owning ref\n", i);
				return -EINVAL;
			}
			if (!type_is_non_owning_ref(reg->type))
				meta->arg_owning_ref = true;

			rec = reg_btf_record(reg);
			if (!rec) {
				verbose(env, "verifier internal error: Couldn't find btf_record\n");
				return -EFAULT;
			}

			if (rec->refcount_off < 0) {
				verbose(env, "arg#%d doesn't point to a type with bpf_refcount field\n", i);
				return -EINVAL;
			}

			meta->arg_btf = reg->btf;
			meta->arg_btf_id = reg->btf_id;
			break;
		case KF_ARG_PTR_TO_CONST_STR:
			if (reg->type != PTR_TO_MAP_VALUE) {
				verbose(env, "arg#%d doesn't point to a const string\n", i);
				return -EINVAL;
			}
			ret = check_reg_const_str(env, reg, regno);
			if (ret)
				return ret;
			break;
		case KF_ARG_PTR_TO_WORKQUEUE:
			if (reg->type != PTR_TO_MAP_VALUE) {
				verbose(env, "arg#%d doesn't point to a map value\n", i);
				return -EINVAL;
			}
			ret = process_wq_func(env, regno, meta);
			if (ret < 0)
				return ret;
			break;
		}
	}

	if (is_kfunc_release(meta) && !meta->release_regno) {
		verbose(env, "release kernel function %s expects refcounted PTR_TO_BTF_ID\n",
			func_name);
		return -EINVAL;
	}

	return 0;
}

static int fetch_kfunc_meta(struct bpf_verifier_env *env,
			    struct bpf_insn *insn,
			    struct bpf_kfunc_call_arg_meta *meta,
			    const char **kfunc_name)
{
	const struct btf_type *func, *func_proto;
	u32 func_id, *kfunc_flags;
	const char *func_name;
	struct btf *desc_btf;

	if (kfunc_name)
		*kfunc_name = NULL;

	if (!insn->imm)
		return -EINVAL;

	desc_btf = find_kfunc_desc_btf(env, insn->off);
	if (IS_ERR(desc_btf))
		return PTR_ERR(desc_btf);

	func_id = insn->imm;
	func = btf_type_by_id(desc_btf, func_id);
	func_name = btf_name_by_offset(desc_btf, func->name_off);
	if (kfunc_name)
		*kfunc_name = func_name;
	func_proto = btf_type_by_id(desc_btf, func->type);

	kfunc_flags = btf_kfunc_id_set_contains(desc_btf, func_id, env->prog);
	if (!kfunc_flags) {
		return -EACCES;
	}

	memset(meta, 0, sizeof(*meta));
	meta->btf = desc_btf;
	meta->func_id = func_id;
	meta->kfunc_flags = *kfunc_flags;
	meta->func_proto = func_proto;
	meta->func_name = func_name;

	return 0;
}

static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name);

static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
			    int *insn_idx_p)
{
	bool sleepable, rcu_lock, rcu_unlock, preempt_disable, preempt_enable;
	u32 i, nargs, ptr_type_id, release_ref_obj_id;
	struct bpf_reg_state *regs = cur_regs(env);
	const char *func_name, *ptr_type_name;
	const struct btf_type *t, *ptr_type;
	struct bpf_kfunc_call_arg_meta meta;
	struct bpf_insn_aux_data *insn_aux;
	int err, insn_idx = *insn_idx_p;
	const struct btf_param *args;
	const struct btf_type *ret_t;
	struct btf *desc_btf;

	/* skip for now, but return error when we find this in fixup_kfunc_call */
	if (!insn->imm)
		return 0;

	err = fetch_kfunc_meta(env, insn, &meta, &func_name);
	if (err == -EACCES && func_name)
		verbose(env, "calling kernel function %s is not allowed\n", func_name);
	if (err)
		return err;
	desc_btf = meta.btf;
	insn_aux = &env->insn_aux_data[insn_idx];

	insn_aux->is_iter_next = is_iter_next_kfunc(&meta);

	if (is_kfunc_destructive(&meta) && !capable(CAP_SYS_BOOT)) {
		verbose(env, "destructive kfunc calls require CAP_SYS_BOOT capability\n");
		return -EACCES;
	}

	sleepable = is_kfunc_sleepable(&meta);
	if (sleepable && !in_sleepable(env)) {
		verbose(env, "program must be sleepable to call sleepable kfunc %s\n", func_name);
		return -EACCES;
	}

	/* Check the arguments */
	err = check_kfunc_args(env, &meta, insn_idx);
	if (err < 0)
		return err;

	if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) {
		err = push_callback_call(env, insn, insn_idx, meta.subprogno,
					 set_rbtree_add_callback_state);
		if (err) {
			verbose(env, "kfunc %s#%d failed callback verification\n",
				func_name, meta.func_id);
			return err;
		}
	}

	if (meta.func_id == special_kfunc_list[KF_bpf_session_cookie]) {
		meta.r0_size = sizeof(u64);
		meta.r0_rdonly = false;
	}

	if (is_bpf_wq_set_callback_impl_kfunc(meta.func_id)) {
		err = push_callback_call(env, insn, insn_idx, meta.subprogno,
					 set_timer_callback_state);
		if (err) {
			verbose(env, "kfunc %s#%d failed callback verification\n",
				func_name, meta.func_id);
			return err;
		}
	}

	rcu_lock = is_kfunc_bpf_rcu_read_lock(&meta);
	rcu_unlock = is_kfunc_bpf_rcu_read_unlock(&meta);

	preempt_disable = is_kfunc_bpf_preempt_disable(&meta);
	preempt_enable = is_kfunc_bpf_preempt_enable(&meta);

	if (env->cur_state->active_rcu_lock) {
		struct bpf_func_state *state;
		struct bpf_reg_state *reg;
		u32 clear_mask = (1 << STACK_SPILL) | (1 << STACK_ITER);

		if (in_rbtree_lock_required_cb(env) && (rcu_lock || rcu_unlock)) {
			verbose(env, "Calling bpf_rcu_read_{lock,unlock} in unnecessary rbtree callback\n");
			return -EACCES;
		}

		if (rcu_lock) {
			verbose(env, "nested rcu read lock (kernel function %s)\n", func_name);
			return -EINVAL;
		} else if (rcu_unlock) {
			bpf_for_each_reg_in_vstate_mask(env->cur_state, state, reg, clear_mask, ({
				if (reg->type & MEM_RCU) {
					reg->type &= ~(MEM_RCU | PTR_MAYBE_NULL);
					reg->type |= PTR_UNTRUSTED;
				}
			}));
			env->cur_state->active_rcu_lock = false;
		} else if (sleepable) {
			verbose(env, "kernel func %s is sleepable within rcu_read_lock region\n", func_name);
			return -EACCES;
		}
	} else if (rcu_lock) {
		env->cur_state->active_rcu_lock = true;
	} else if (rcu_unlock) {
		verbose(env, "unmatched rcu read unlock (kernel function %s)\n", func_name);
		return -EINVAL;
	}

	if (env->cur_state->active_preempt_lock) {
		if (preempt_disable) {
			env->cur_state->active_preempt_lock++;
		} else if (preempt_enable) {
			env->cur_state->active_preempt_lock--;
		} else if (sleepable) {
			verbose(env, "kernel func %s is sleepable within non-preemptible region\n", func_name);
			return -EACCES;
		}
	} else if (preempt_disable) {
		env->cur_state->active_preempt_lock++;
	} else if (preempt_enable) {
		verbose(env, "unmatched attempt to enable preemption (kernel function %s)\n", func_name);
		return -EINVAL;
	}

	/* In case of release function, we get register number of refcounted
	 * PTR_TO_BTF_ID in bpf_kfunc_arg_meta, do the release now.
	 */
	if (meta.release_regno) {
		err = release_reference(env, regs[meta.release_regno].ref_obj_id);
		if (err) {
			verbose(env, "kfunc %s#%d reference has not been acquired before\n",
				func_name, meta.func_id);
			return err;
		}
	}

	if (meta.func_id == special_kfunc_list[KF_bpf_list_push_front_impl] ||
	    meta.func_id == special_kfunc_list[KF_bpf_list_push_back_impl] ||
	    meta.func_id == special_kfunc_list[KF_bpf_rbtree_add_impl]) {
		release_ref_obj_id = regs[BPF_REG_2].ref_obj_id;
		insn_aux->insert_off = regs[BPF_REG_2].off;
		insn_aux->kptr_struct_meta = btf_find_struct_meta(meta.arg_btf, meta.arg_btf_id);
		err = ref_convert_owning_non_owning(env, release_ref_obj_id);
		if (err) {
			verbose(env, "kfunc %s#%d conversion of owning ref to non-owning failed\n",
				func_name, meta.func_id);
			return err;
		}

		err = release_reference(env, release_ref_obj_id);
		if (err) {
			verbose(env, "kfunc %s#%d reference has not been acquired before\n",
				func_name, meta.func_id);
			return err;
		}
	}

	if (meta.func_id == special_kfunc_list[KF_bpf_throw]) {
		if (!bpf_jit_supports_exceptions()) {
			verbose(env, "JIT does not support calling kfunc %s#%d\n",
				func_name, meta.func_id);
			return -ENOTSUPP;
		}
		env->seen_exception = true;

		/* In the case of the default callback, the cookie value passed
		 * to bpf_throw becomes the return value of the program.
		 */
		if (!env->exception_callback_subprog) {
			err = check_return_code(env, BPF_REG_1, "R1");
			if (err < 0)
				return err;
		}
	}

	for (i = 0; i < CALLER_SAVED_REGS; i++)
		mark_reg_not_init(env, regs, caller_saved[i]);

	/* Check return type */
	t = btf_type_skip_modifiers(desc_btf, meta.func_proto->type, NULL);

	if (is_kfunc_acquire(&meta) && !btf_type_is_struct_ptr(meta.btf, t)) {
		/* Only exception is bpf_obj_new_impl */
		if (meta.btf != btf_vmlinux ||
		    (meta.func_id != special_kfunc_list[KF_bpf_obj_new_impl] &&
		     meta.func_id != special_kfunc_list[KF_bpf_percpu_obj_new_impl] &&
		     meta.func_id != special_kfunc_list[KF_bpf_refcount_acquire_impl])) {
			verbose(env, "acquire kernel function does not return PTR_TO_BTF_ID\n");
			return -EINVAL;
		}
	}

	if (btf_type_is_scalar(t)) {
		mark_reg_unknown(env, regs, BPF_REG_0);
		mark_btf_func_reg_size(env, BPF_REG_0, t->size);
	} else if (btf_type_is_ptr(t)) {
		ptr_type = btf_type_skip_modifiers(desc_btf, t->type, &ptr_type_id);

		if (meta.btf == btf_vmlinux && btf_id_set_contains(&special_kfunc_set, meta.func_id)) {
			if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] ||
			    meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) {
				struct btf_struct_meta *struct_meta;
				struct btf *ret_btf;
				u32 ret_btf_id;

				if (meta.func_id == special_kfunc_list[KF_bpf_obj_new_impl] && !bpf_global_ma_set)
					return -ENOMEM;

				if (((u64)(u32)meta.arg_constant.value) != meta.arg_constant.value) {
					verbose(env, "local type ID argument must be in range [0, U32_MAX]\n");
					return -EINVAL;
				}

				ret_btf = env->prog->aux->btf;
				ret_btf_id = meta.arg_constant.value;

				/* This may be NULL due to user not supplying a BTF */
				if (!ret_btf) {
					verbose(env, "bpf_obj_new/bpf_percpu_obj_new requires prog BTF\n");
					return -EINVAL;
				}

				ret_t = btf_type_by_id(ret_btf, ret_btf_id);
				if (!ret_t || !__btf_type_is_struct(ret_t)) {
					verbose(env, "bpf_obj_new/bpf_percpu_obj_new type ID argument must be of a struct\n");
					return -EINVAL;
				}

				if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) {
					if (ret_t->size > BPF_GLOBAL_PERCPU_MA_MAX_SIZE) {
						verbose(env, "bpf_percpu_obj_new type size (%d) is greater than %d\n",
							ret_t->size, BPF_GLOBAL_PERCPU_MA_MAX_SIZE);
						return -EINVAL;
					}

					if (!bpf_global_percpu_ma_set) {
						mutex_lock(&bpf_percpu_ma_lock);
						if (!bpf_global_percpu_ma_set) {
							/* Charge memory allocated with bpf_global_percpu_ma to
							 * root memcg. The obj_cgroup for root memcg is NULL.
							 */
							err = bpf_mem_alloc_percpu_init(&bpf_global_percpu_ma, NULL);
							if (!err)
								bpf_global_percpu_ma_set = true;
						}
						mutex_unlock(&bpf_percpu_ma_lock);
						if (err)
							return err;
					}

					mutex_lock(&bpf_percpu_ma_lock);
					err = bpf_mem_alloc_percpu_unit_init(&bpf_global_percpu_ma, ret_t->size);
					mutex_unlock(&bpf_percpu_ma_lock);
					if (err)
						return err;
				}

				struct_meta = btf_find_struct_meta(ret_btf, ret_btf_id);
				if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) {
					if (!__btf_type_is_scalar_struct(env, ret_btf, ret_t, 0)) {
						verbose(env, "bpf_percpu_obj_new type ID argument must be of a struct of scalars\n");
						return -EINVAL;
					}

					if (struct_meta) {
						verbose(env, "bpf_percpu_obj_new type ID argument must not contain special fields\n");
						return -EINVAL;
					}
				}

				mark_reg_known_zero(env, regs, BPF_REG_0);
				regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC;
				regs[BPF_REG_0].btf = ret_btf;
				regs[BPF_REG_0].btf_id = ret_btf_id;
				if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl])
					regs[BPF_REG_0].type |= MEM_PERCPU;

				insn_aux->obj_new_size = ret_t->size;
				insn_aux->kptr_struct_meta = struct_meta;
			} else if (meta.func_id == special_kfunc_list[KF_bpf_refcount_acquire_impl]) {
				mark_reg_known_zero(env, regs, BPF_REG_0);
				regs[BPF_REG_0].type = PTR_TO_BTF_ID | MEM_ALLOC;
				regs[BPF_REG_0].btf = meta.arg_btf;
				regs[BPF_REG_0].btf_id = meta.arg_btf_id;

				insn_aux->kptr_struct_meta =
					btf_find_struct_meta(meta.arg_btf,
							     meta.arg_btf_id);
			} else if (meta.func_id == special_kfunc_list[KF_bpf_list_pop_front] ||
				   meta.func_id == special_kfunc_list[KF_bpf_list_pop_back]) {
				struct btf_field *field = meta.arg_list_head.field;

				mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root);
			} else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_remove] ||
				   meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) {
				struct btf_field *field = meta.arg_rbtree_root.field;

				mark_reg_graph_node(regs, BPF_REG_0, &field->graph_root);
			} else if (meta.func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx]) {
				mark_reg_known_zero(env, regs, BPF_REG_0);
				regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_TRUSTED;
				regs[BPF_REG_0].btf = desc_btf;
				regs[BPF_REG_0].btf_id = meta.ret_btf_id;
			} else if (meta.func_id == special_kfunc_list[KF_bpf_rdonly_cast]) {
				ret_t = btf_type_by_id(desc_btf, meta.arg_constant.value);
				if (!ret_t || !btf_type_is_struct(ret_t)) {
					verbose(env,
						"kfunc bpf_rdonly_cast type ID argument must be of a struct\n");
					return -EINVAL;
				}

				mark_reg_known_zero(env, regs, BPF_REG_0);
				regs[BPF_REG_0].type = PTR_TO_BTF_ID | PTR_UNTRUSTED;
				regs[BPF_REG_0].btf = desc_btf;
				regs[BPF_REG_0].btf_id = meta.arg_constant.value;
			} else if (meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice] ||
				   meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice_rdwr]) {
				enum bpf_type_flag type_flag = get_dynptr_type_flag(meta.initialized_dynptr.type);

				mark_reg_known_zero(env, regs, BPF_REG_0);

				if (!meta.arg_constant.found) {
					verbose(env, "verifier internal error: bpf_dynptr_slice(_rdwr) no constant size\n");
					return -EFAULT;
				}

				regs[BPF_REG_0].mem_size = meta.arg_constant.value;

				/* PTR_MAYBE_NULL will be added when is_kfunc_ret_null is checked */
				regs[BPF_REG_0].type = PTR_TO_MEM | type_flag;

				if (meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice]) {
					regs[BPF_REG_0].type |= MEM_RDONLY;
				} else {
					/* this will set env->seen_direct_write to true */
					if (!may_access_direct_pkt_data(env, NULL, BPF_WRITE)) {
						verbose(env, "the prog does not allow writes to packet data\n");
						return -EINVAL;
					}
				}

				if (!meta.initialized_dynptr.id) {
					verbose(env, "verifier internal error: no dynptr id\n");
					return -EFAULT;
				}
				regs[BPF_REG_0].dynptr_id = meta.initialized_dynptr.id;

				/* we don't need to set BPF_REG_0's ref obj id
				 * because packet slices are not refcounted (see
				 * dynptr_type_refcounted)
				 */
			} else {
				verbose(env, "kernel function %s unhandled dynamic return type\n",
					meta.func_name);
				return -EFAULT;
			}
		} else if (btf_type_is_void(ptr_type)) {
			/* kfunc returning 'void *' is equivalent to returning scalar */
			mark_reg_unknown(env, regs, BPF_REG_0);
		} else if (!__btf_type_is_struct(ptr_type)) {
			if (!meta.r0_size) {
				__u32 sz;

				if (!IS_ERR(btf_resolve_size(desc_btf, ptr_type, &sz))) {
					meta.r0_size = sz;
					meta.r0_rdonly = true;
				}
			}
			if (!meta.r0_size) {
				ptr_type_name = btf_name_by_offset(desc_btf,
								   ptr_type->name_off);
				verbose(env,
					"kernel function %s returns pointer type %s %s is not supported\n",
					func_name,
					btf_type_str(ptr_type),
					ptr_type_name);
				return -EINVAL;
			}

			mark_reg_known_zero(env, regs, BPF_REG_0);
			regs[BPF_REG_0].type = PTR_TO_MEM;
			regs[BPF_REG_0].mem_size = meta.r0_size;

			if (meta.r0_rdonly)
				regs[BPF_REG_0].type |= MEM_RDONLY;

			/* Ensures we don't access the memory after a release_reference() */
			if (meta.ref_obj_id)
				regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
		} else {
			mark_reg_known_zero(env, regs, BPF_REG_0);
			regs[BPF_REG_0].btf = desc_btf;
			regs[BPF_REG_0].type = PTR_TO_BTF_ID;
			regs[BPF_REG_0].btf_id = ptr_type_id;

			if (is_iter_next_kfunc(&meta)) {
				struct bpf_reg_state *cur_iter;

				cur_iter = get_iter_from_state(env->cur_state, &meta);

				if (cur_iter->type & MEM_RCU) /* KF_RCU_PROTECTED */
					regs[BPF_REG_0].type |= MEM_RCU;
				else
					regs[BPF_REG_0].type |= PTR_TRUSTED;
			}
		}

		if (is_kfunc_ret_null(&meta)) {
			regs[BPF_REG_0].type |= PTR_MAYBE_NULL;
			/* For mark_ptr_or_null_reg, see 93c230e3f5bd6 */
			regs[BPF_REG_0].id = ++env->id_gen;
		}
		mark_btf_func_reg_size(env, BPF_REG_0, sizeof(void *));
		if (is_kfunc_acquire(&meta)) {
			int id = acquire_reference_state(env, insn_idx);

			if (id < 0)
				return id;
			if (is_kfunc_ret_null(&meta))
				regs[BPF_REG_0].id = id;
			regs[BPF_REG_0].ref_obj_id = id;
		} else if (meta.func_id == special_kfunc_list[KF_bpf_rbtree_first]) {
			ref_set_non_owning(env, &regs[BPF_REG_0]);
		}

		if (reg_may_point_to_spin_lock(&regs[BPF_REG_0]) && !regs[BPF_REG_0].id)
			regs[BPF_REG_0].id = ++env->id_gen;
	} else if (btf_type_is_void(t)) {
		if (meta.btf == btf_vmlinux && btf_id_set_contains(&special_kfunc_set, meta.func_id)) {
			if (meta.func_id == special_kfunc_list[KF_bpf_obj_drop_impl] ||
			    meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_drop_impl]) {
				insn_aux->kptr_struct_meta =
					btf_find_struct_meta(meta.arg_btf,
							     meta.arg_btf_id);
			}
		}
	}

	nargs = btf_type_vlen(meta.func_proto);
	args = (const struct btf_param *)(meta.func_proto + 1);
	for (i = 0; i < nargs; i++) {
		u32 regno = i + 1;

		t = btf_type_skip_modifiers(desc_btf, args[i].type, NULL);
		if (btf_type_is_ptr(t))
			mark_btf_func_reg_size(env, regno, sizeof(void *));
		else
			/* scalar. ensured by btf_check_kfunc_arg_match() */
			mark_btf_func_reg_size(env, regno, t->size);
	}

	if (is_iter_next_kfunc(&meta)) {
		err = process_iter_next_call(env, insn_idx, &meta);
		if (err)
			return err;
	}

	return 0;
}

static bool check_reg_sane_offset(struct bpf_verifier_env *env,
				  const struct bpf_reg_state *reg,
				  enum bpf_reg_type type)
{
	bool known = tnum_is_const(reg->var_off);
	s64 val = reg->var_off.value;
	s64 smin = reg->smin_value;

	if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) {
		verbose(env, "math between %s pointer and %lld is not allowed\n",
			reg_type_str(env, type), val);
		return false;
	}

	if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) {
		verbose(env, "%s pointer offset %d is not allowed\n",
			reg_type_str(env, type), reg->off);
		return false;
	}

	if (smin == S64_MIN) {
		verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n",
			reg_type_str(env, type));
		return false;
	}

	if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) {
		verbose(env, "value %lld makes %s pointer be out of bounds\n",
			smin, reg_type_str(env, type));
		return false;
	}

	return true;
}

enum {
	REASON_BOUNDS	= -1,
	REASON_TYPE	= -2,
	REASON_PATHS	= -3,
	REASON_LIMIT	= -4,
	REASON_STACK	= -5,
};

static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg,
			      u32 *alu_limit, bool mask_to_left)
{
	u32 max = 0, ptr_limit = 0;

	switch (ptr_reg->type) {
	case PTR_TO_STACK:
		/* Offset 0 is out-of-bounds, but acceptable start for the
		 * left direction, see BPF_REG_FP. Also, unknown scalar
		 * offset where we would need to deal with min/max bounds is
		 * currently prohibited for unprivileged.
		 */
		max = MAX_BPF_STACK + mask_to_left;
		ptr_limit = -(ptr_reg->var_off.value + ptr_reg->off);
		break;
	case PTR_TO_MAP_VALUE:
		max = ptr_reg->map_ptr->value_size;
		ptr_limit = (mask_to_left ?
			     ptr_reg->smin_value :
			     ptr_reg->umax_value) + ptr_reg->off;
		break;
	default:
		return REASON_TYPE;
	}

	if (ptr_limit >= max)
		return REASON_LIMIT;
	*alu_limit = ptr_limit;
	return 0;
}

static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env,
				    const struct bpf_insn *insn)
{
	return env->bypass_spec_v1 || BPF_SRC(insn->code) == BPF_K;
}

static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux,
				       u32 alu_state, u32 alu_limit)
{
	/* If we arrived here from different branches with different
	 * state or limits to sanitize, then this won't work.
	 */
	if (aux->alu_state &&
	    (aux->alu_state != alu_state ||
	     aux->alu_limit != alu_limit))
		return REASON_PATHS;

	/* Corresponding fixup done in do_misc_fixups(). */
	aux->alu_state = alu_state;
	aux->alu_limit = alu_limit;
	return 0;
}

static int sanitize_val_alu(struct bpf_verifier_env *env,
			    struct bpf_insn *insn)
{
	struct bpf_insn_aux_data *aux = cur_aux(env);

	if (can_skip_alu_sanitation(env, insn))
		return 0;

	return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
}

static bool sanitize_needed(u8 opcode)
{
	return opcode == BPF_ADD || opcode == BPF_SUB;
}

struct bpf_sanitize_info {
	struct bpf_insn_aux_data aux;
	bool mask_to_left;
};

static struct bpf_verifier_state *
sanitize_speculative_path(struct bpf_verifier_env *env,
			  const struct bpf_insn *insn,
			  u32 next_idx, u32 curr_idx)
{
	struct bpf_verifier_state *branch;
	struct bpf_reg_state *regs;

	branch = push_stack(env, next_idx, curr_idx, true);
	if (branch && insn) {
		regs = branch->frame[branch->curframe]->regs;
		if (BPF_SRC(insn->code) == BPF_K) {
			mark_reg_unknown(env, regs, insn->dst_reg);
		} else if (BPF_SRC(insn->code) == BPF_X) {
			mark_reg_unknown(env, regs, insn->dst_reg);
			mark_reg_unknown(env, regs, insn->src_reg);
		}
	}
	return branch;
}

static int sanitize_ptr_alu(struct bpf_verifier_env *env,
			    struct bpf_insn *insn,
			    const struct bpf_reg_state *ptr_reg,
			    const struct bpf_reg_state *off_reg,
			    struct bpf_reg_state *dst_reg,
			    struct bpf_sanitize_info *info,
			    const bool commit_window)
{
	struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : &info->aux;
	struct bpf_verifier_state *vstate = env->cur_state;
	bool off_is_imm = tnum_is_const(off_reg->var_off);
	bool off_is_neg = off_reg->smin_value < 0;
	bool ptr_is_dst_reg = ptr_reg == dst_reg;
	u8 opcode = BPF_OP(insn->code);
	u32 alu_state, alu_limit;
	struct bpf_reg_state tmp;
	bool ret;
	int err;

	if (can_skip_alu_sanitation(env, insn))
		return 0;

	/* We already marked aux for masking from non-speculative
	 * paths, thus we got here in the first place. We only care
	 * to explore bad access from here.
	 */
	if (vstate->speculative)
		goto do_sim;

	if (!commit_window) {
		if (!tnum_is_const(off_reg->var_off) &&
		    (off_reg->smin_value < 0) != (off_reg->smax_value < 0))
			return REASON_BOUNDS;

		info->mask_to_left = (opcode == BPF_ADD &&  off_is_neg) ||
				     (opcode == BPF_SUB && !off_is_neg);
	}

	err = retrieve_ptr_limit(ptr_reg, &alu_limit, info->mask_to_left);
	if (err < 0)
		return err;

	if (commit_window) {
		/* In commit phase we narrow the masking window based on
		 * the observed pointer move after the simulated operation.
		 */
		alu_state = info->aux.alu_state;
		alu_limit = abs(info->aux.alu_limit - alu_limit);
	} else {
		alu_state  = off_is_neg ? BPF_ALU_NEG_VALUE : 0;
		alu_state |= off_is_imm ? BPF_ALU_IMMEDIATE : 0;
		alu_state |= ptr_is_dst_reg ?
			     BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;

		/* Limit pruning on unknown scalars to enable deep search for
		 * potential masking differences from other program paths.
		 */
		if (!off_is_imm)
			env->explore_alu_limits = true;
	}

	err = update_alu_sanitation_state(aux, alu_state, alu_limit);
	if (err < 0)
		return err;
do_sim:
	/* If we're in commit phase, we're done here given we already
	 * pushed the truncated dst_reg into the speculative verification
	 * stack.
	 *
	 * Also, when register is a known constant, we rewrite register-based
	 * operation to immediate-based, and thus do not need masking (and as
	 * a consequence, do not need to simulate the zero-truncation either).
	 */
	if (commit_window || off_is_imm)
		return 0;

	/* Simulate and find potential out-of-bounds access under
	 * speculative execution from truncation as a result of
	 * masking when off was not within expected range. If off
	 * sits in dst, then we temporarily need to move ptr there
	 * to simulate dst (== 0) +/-= ptr. Needed, for example,
	 * for cases where we use K-based arithmetic in one direction
	 * and truncated reg-based in the other in order to explore
	 * bad access.
	 */
	if (!ptr_is_dst_reg) {
		tmp = *dst_reg;
		copy_register_state(dst_reg, ptr_reg);
	}
	ret = sanitize_speculative_path(env, NULL, env->insn_idx + 1,
					env->insn_idx);
	if (!ptr_is_dst_reg && ret)
		*dst_reg = tmp;
	return !ret ? REASON_STACK : 0;
}

static void sanitize_mark_insn_seen(struct bpf_verifier_env *env)
{
	struct bpf_verifier_state *vstate = env->cur_state;

	/* If we simulate paths under speculation, we don't update the
	 * insn as 'seen' such that when we verify unreachable paths in
	 * the non-speculative domain, sanitize_dead_code() can still
	 * rewrite/sanitize them.
	 */
	if (!vstate->speculative)
		env->insn_aux_data[env->insn_idx].seen = env->pass_cnt;
}

static int sanitize_err(struct bpf_verifier_env *env,
			const struct bpf_insn *insn, int reason,
			const struct bpf_reg_state *off_reg,
			const struct bpf_reg_state *dst_reg)
{
	static const char *err = "pointer arithmetic with it prohibited for !root";
	const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub";
	u32 dst = insn->dst_reg, src = insn->src_reg;

	switch (reason) {
	case REASON_BOUNDS:
		verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n",
			off_reg == dst_reg ? dst : src, err);
		break;
	case REASON_TYPE:
		verbose(env, "R%d has pointer with unsupported alu operation, %s\n",
			off_reg == dst_reg ? src : dst, err);
		break;
	case REASON_PATHS:
		verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n",
			dst, op, err);
		break;
	case REASON_LIMIT:
		verbose(env, "R%d tried to %s beyond pointer bounds, %s\n",
			dst, op, err);
		break;
	case REASON_STACK:
		verbose(env, "R%d could not be pushed for speculative verification, %s\n",
			dst, err);
		break;
	default:
		verbose(env, "verifier internal error: unknown reason (%d)\n",
			reason);
		break;
	}

	return -EACCES;
}

/* check that stack access falls within stack limits and that 'reg' doesn't
 * have a variable offset.
 *
 * Variable offset is prohibited for unprivileged mode for simplicity since it
 * requires corresponding support in Spectre masking for stack ALU.  See also
 * retrieve_ptr_limit().
 *
 *
 * 'off' includes 'reg->off'.
 */
static int check_stack_access_for_ptr_arithmetic(
				struct bpf_verifier_env *env,
				int regno,
				const struct bpf_reg_state *reg,
				int off)
{
	if (!tnum_is_const(reg->var_off)) {
		char tn_buf[48];

		tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
		verbose(env, "R%d variable stack access prohibited for !root, var_off=%s off=%d\n",
			regno, tn_buf, off);
		return -EACCES;
	}

	if (off >= 0 || off < -MAX_BPF_STACK) {
		verbose(env, "R%d stack pointer arithmetic goes out of range, "
			"prohibited for !root; off=%d\n", regno, off);
		return -EACCES;
	}

	return 0;
}

static int sanitize_check_bounds(struct bpf_verifier_env *env,
				 const struct bpf_insn *insn,
				 const struct bpf_reg_state *dst_reg)
{
	u32 dst = insn->dst_reg;

	/* For unprivileged we require that resulting offset must be in bounds
	 * in order to be able to sanitize access later on.
	 */
	if (env->bypass_spec_v1)
		return 0;

	switch (dst_reg->type) {
	case PTR_TO_STACK:
		if (check_stack_access_for_ptr_arithmetic(env, dst, dst_reg,
					dst_reg->off + dst_reg->var_off.value))
			return -EACCES;
		break;
	case PTR_TO_MAP_VALUE:
		if (check_map_access(env, dst, dst_reg->off, 1, false, ACCESS_HELPER)) {
			verbose(env, "R%d pointer arithmetic of map value goes out of range, "
				"prohibited for !root\n", dst);
			return -EACCES;
		}
		break;
	default:
		break;
	}

	return 0;
}

/* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
 * Caller should also handle BPF_MOV case separately.
 * If we return -EACCES, caller may want to try again treating pointer as a
 * scalar.  So we only emit a diagnostic if !env->allow_ptr_leaks.
 */
static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
				   struct bpf_insn *insn,
				   const struct bpf_reg_state *ptr_reg,
				   const struct bpf_reg_state *off_reg)
{
	struct bpf_verifier_state *vstate = env->cur_state;
	struct bpf_func_state *state = vstate->frame[vstate->curframe];
	struct bpf_reg_state *regs = state->regs, *dst_reg;
	bool known = tnum_is_const(off_reg->var_off);
	s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value,
	    smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value;
	u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value,
	    umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value;
	struct bpf_sanitize_info info = {};
	u8 opcode = BPF_OP(insn->code);
	u32 dst = insn->dst_reg;
	int ret;

	dst_reg = &regs[dst];

	if ((known && (smin_val != smax_val || umin_val != umax_val)) ||
	    smin_val > smax_val || umin_val > umax_val) {
		/* Taint dst register if offset had invalid bounds derived from
		 * e.g. dead branches.
		 */
		__mark_reg_unknown(env, dst_reg);
		return 0;
	}

	if (BPF_CLASS(insn->code) != BPF_ALU64) {
		/* 32-bit ALU ops on pointers produce (meaningless) scalars */
		if (opcode == BPF_SUB && env->allow_ptr_leaks) {
			__mark_reg_unknown(env, dst_reg);
			return 0;
		}

		verbose(env,
			"R%d 32-bit pointer arithmetic prohibited\n",
			dst);
		return -EACCES;
	}

	if (ptr_reg->type & PTR_MAYBE_NULL) {
		verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n",
			dst, reg_type_str(env, ptr_reg->type));
		return -EACCES;
	}

	switch (base_type(ptr_reg->type)) {
	case PTR_TO_CTX:
	case PTR_TO_MAP_VALUE:
	case PTR_TO_MAP_KEY:
	case PTR_TO_STACK:
	case PTR_TO_PACKET_META:
	case PTR_TO_PACKET:
	case PTR_TO_TP_BUFFER:
	case PTR_TO_BTF_ID:
	case PTR_TO_MEM:
	case PTR_TO_BUF:
	case PTR_TO_FUNC:
	case CONST_PTR_TO_DYNPTR:
		break;
	case PTR_TO_FLOW_KEYS:
		if (known)
			break;
		fallthrough;
	case CONST_PTR_TO_MAP:
		/* smin_val represents the known value */
		if (known && smin_val == 0 && opcode == BPF_ADD)
			break;
		fallthrough;
	default:
		verbose(env, "R%d pointer arithmetic on %s prohibited\n",
			dst, reg_type_str(env, ptr_reg->type));
		return -EACCES;
	}

	/* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
	 * The id may be overwritten later if we create a new variable offset.
	 */
	dst_reg->type = ptr_reg->type;
	dst_reg->id = ptr_reg->id;

	if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) ||
	    !check_reg_sane_offset(env, ptr_reg, ptr_reg->type))
		return -EINVAL;

	/* pointer types do not carry 32-bit bounds at the moment. */
	__mark_reg32_unbounded(dst_reg);

	if (sanitize_needed(opcode)) {
		ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg,
				       &info, false);
		if (ret < 0)
			return sanitize_err(env, insn, ret, off_reg, dst_reg);
	}

	switch (opcode) {
	case BPF_ADD:
		/* We can take a fixed offset as long as it doesn't overflow
		 * the s32 'off' field
		 */
		if (known && (ptr_reg->off + smin_val ==
			      (s64)(s32)(ptr_reg->off + smin_val))) {
			/* pointer += K.  Accumulate it into fixed offset */
			dst_reg->smin_value = smin_ptr;
			dst_reg->smax_value = smax_ptr;
			dst_reg->umin_value = umin_ptr;
			dst_reg->umax_value = umax_ptr;
			dst_reg->var_off = ptr_reg->var_off;
			dst_reg->off = ptr_reg->off + smin_val;
			dst_reg->raw = ptr_reg->raw;
			break;
		}
		/* A new variable offset is created.  Note that off_reg->off
		 * == 0, since it's a scalar.
		 * dst_reg gets the pointer type and since some positive
		 * integer value was added to the pointer, give it a new 'id'
		 * if it's a PTR_TO_PACKET.
		 * this creates a new 'base' pointer, off_reg (variable) gets
		 * added into the variable offset, and we copy the fixed offset
		 * from ptr_reg.
		 */
		if (check_add_overflow(smin_ptr, smin_val, &dst_reg->smin_value) ||
		    check_add_overflow(smax_ptr, smax_val, &dst_reg->smax_value)) {
			dst_reg->smin_value = S64_MIN;
			dst_reg->smax_value = S64_MAX;
		}
		if (check_add_overflow(umin_ptr, umin_val, &dst_reg->umin_value) ||
		    check_add_overflow(umax_ptr, umax_val, &dst_reg->umax_value)) {
			dst_reg->umin_value = 0;
			dst_reg->umax_value = U64_MAX;
		}
		dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off);
		dst_reg->off = ptr_reg->off;
		dst_reg->raw = ptr_reg->raw;
		if (reg_is_pkt_pointer(ptr_reg)) {
			dst_reg->id = ++env->id_gen;
			/* something was added to pkt_ptr, set range to zero */
			memset(&dst_reg->raw, 0, sizeof(dst_reg->raw));
		}
		break;
	case BPF_SUB:
		if (dst_reg == off_reg) {
			/* scalar -= pointer.  Creates an unknown scalar */
			verbose(env, "R%d tried to subtract pointer from scalar\n",
				dst);
			return -EACCES;
		}
		/* We don't allow subtraction from FP, because (according to
		 * test_verifier.c test "invalid fp arithmetic", JITs might not
		 * be able to deal with it.
		 */
		if (ptr_reg->type == PTR_TO_STACK) {
			verbose(env, "R%d subtraction from stack pointer prohibited\n",
				dst);
			return -EACCES;
		}
		if (known && (ptr_reg->off - smin_val ==
			      (s64)(s32)(ptr_reg->off - smin_val))) {
			/* pointer -= K.  Subtract it from fixed offset */
			dst_reg->smin_value = smin_ptr;
			dst_reg->smax_value = smax_ptr;
			dst_reg->umin_value = umin_ptr;
			dst_reg->umax_value = umax_ptr;
			dst_reg->var_off = ptr_reg->var_off;
			dst_reg->id = ptr_reg->id;
			dst_reg->off = ptr_reg->off - smin_val;
			dst_reg->raw = ptr_reg->raw;
			break;
		}
		/* A new variable offset is created.  If the subtrahend is known
		 * nonnegative, then any reg->range we had before is still good.
		 */
		if (check_sub_overflow(smin_ptr, smax_val, &dst_reg->smin_value) ||
		    check_sub_overflow(smax_ptr, smin_val, &dst_reg->smax_value)) {
			/* Overflow possible, we know nothing */
			dst_reg->smin_value = S64_MIN;
			dst_reg->smax_value = S64_MAX;
		}
		if (umin_ptr < umax_val) {
			/* Overflow possible, we know nothing */
			dst_reg->umin_value = 0;
			dst_reg->umax_value = U64_MAX;
		} else {
			/* Cannot overflow (as long as bounds are consistent) */
			dst_reg->umin_value = umin_ptr - umax_val;
			dst_reg->umax_value = umax_ptr - umin_val;
		}
		dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off);
		dst_reg->off = ptr_reg->off;
		dst_reg->raw = ptr_reg->raw;
		if (reg_is_pkt_pointer(ptr_reg)) {
			dst_reg->id = ++env->id_gen;
			/* something was added to pkt_ptr, set range to zero */
			if (smin_val < 0)
				memset(&dst_reg->raw, 0, sizeof(dst_reg->raw));
		}
		break;
	case BPF_AND:
	case BPF_OR:
	case BPF_XOR:
		/* bitwise ops on pointers are troublesome, prohibit. */
		verbose(env, "R%d bitwise operator %s on pointer prohibited\n",
			dst, bpf_alu_string[opcode >> 4]);
		return -EACCES;
	default:
		/* other operators (e.g. MUL,LSH) produce non-pointer results */
		verbose(env, "R%d pointer arithmetic with %s operator prohibited\n",
			dst, bpf_alu_string[opcode >> 4]);
		return -EACCES;
	}

	if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type))
		return -EINVAL;
	reg_bounds_sync(dst_reg);
	if (sanitize_check_bounds(env, insn, dst_reg) < 0)
		return -EACCES;
	if (sanitize_needed(opcode)) {
		ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg,
				       &info, true);
		if (ret < 0)
			return sanitize_err(env, insn, ret, off_reg, dst_reg);
	}

	return 0;
}

static void scalar32_min_max_add(struct bpf_reg_state *dst_reg,
				 struct bpf_reg_state *src_reg)
{
	s32 *dst_smin = &dst_reg->s32_min_value;
	s32 *dst_smax = &dst_reg->s32_max_value;
	u32 *dst_umin = &dst_reg->u32_min_value;
	u32 *dst_umax = &dst_reg->u32_max_value;

	if (check_add_overflow(*dst_smin, src_reg->s32_min_value, dst_smin) ||
	    check_add_overflow(*dst_smax, src_reg->s32_max_value, dst_smax)) {
		*dst_smin = S32_MIN;
		*dst_smax = S32_MAX;
	}
	if (check_add_overflow(*dst_umin, src_reg->u32_min_value, dst_umin) ||
	    check_add_overflow(*dst_umax, src_reg->u32_max_value, dst_umax)) {
		*dst_umin = 0;
		*dst_umax = U32_MAX;
	}
}

static void scalar_min_max_add(struct bpf_reg_state *dst_reg,
			       struct bpf_reg_state *src_reg)
{
	s64 *dst_smin = &dst_reg->smin_value;
	s64 *dst_smax = &dst_reg->smax_value;
	u64 *dst_umin = &dst_reg->umin_value;
	u64 *dst_umax = &dst_reg->umax_value;

	if (check_add_overflow(*dst_smin, src_reg->smin_value, dst_smin) ||
	    check_add_overflow(*dst_smax, src_reg->smax_value, dst_smax)) {
		*dst_smin = S64_MIN;
		*dst_smax = S64_MAX;
	}
	if (check_add_overflow(*dst_umin, src_reg->umin_value, dst_umin) ||
	    check_add_overflow(*dst_umax, src_reg->umax_value, dst_umax)) {
		*dst_umin = 0;
		*dst_umax = U64_MAX;
	}
}

static void scalar32_min_max_sub(struct bpf_reg_state *dst_reg,
				 struct bpf_reg_state *src_reg)
{
	s32 *dst_smin = &dst_reg->s32_min_value;
	s32 *dst_smax = &dst_reg->s32_max_value;
	u32 umin_val = src_reg->u32_min_value;
	u32 umax_val = src_reg->u32_max_value;

	if (check_sub_overflow(*dst_smin, src_reg->s32_max_value, dst_smin) ||
	    check_sub_overflow(*dst_smax, src_reg->s32_min_value, dst_smax)) {
		/* Overflow possible, we know nothing */
		*dst_smin = S32_MIN;
		*dst_smax = S32_MAX;
	}
	if (dst_reg->u32_min_value < umax_val) {
		/* Overflow possible, we know nothing */
		dst_reg->u32_min_value = 0;
		dst_reg->u32_max_value = U32_MAX;
	} else {
		/* Cannot overflow (as long as bounds are consistent) */
		dst_reg->u32_min_value -= umax_val;
		dst_reg->u32_max_value -= umin_val;
	}
}

static void scalar_min_max_sub(struct bpf_reg_state *dst_reg,
			       struct bpf_reg_state *src_reg)
{
	s64 *dst_smin = &dst_reg->smin_value;
	s64 *dst_smax = &dst_reg->smax_value;
	u64 umin_val = src_reg->umin_value;
	u64 umax_val = src_reg->umax_value;

	if (check_sub_overflow(*dst_smin, src_reg->smax_value, dst_smin) ||
	    check_sub_overflow(*dst_smax, src_reg->smin_value, dst_smax)) {
		/* Overflow possible, we know nothing */
		*dst_smin = S64_MIN;
		*dst_smax = S64_MAX;
	}
	if (dst_reg->umin_value < umax_val) {
		/* Overflow possible, we know nothing */
		dst_reg->umin_value = 0;
		dst_reg->umax_value = U64_MAX;
	} else {
		/* Cannot overflow (as long as bounds are consistent) */
		dst_reg->umin_value -= umax_val;
		dst_reg->umax_value -= umin_val;
	}
}

static void scalar32_min_max_mul(struct bpf_reg_state *dst_reg,
				 struct bpf_reg_state *src_reg)
{
	s32 smin_val = src_reg->s32_min_value;
	u32 umin_val = src_reg->u32_min_value;
	u32 umax_val = src_reg->u32_max_value;

	if (smin_val < 0 || dst_reg->s32_min_value < 0) {
		/* Ain't nobody got time to multiply that sign */
		__mark_reg32_unbounded(dst_reg);
		return;
	}
	/* Both values are positive, so we can work with unsigned and
	 * copy the result to signed (unless it exceeds S32_MAX).
	 */
	if (umax_val > U16_MAX || dst_reg->u32_max_value > U16_MAX) {
		/* Potential overflow, we know nothing */
		__mark_reg32_unbounded(dst_reg);
		return;
	}
	dst_reg->u32_min_value *= umin_val;
	dst_reg->u32_max_value *= umax_val;
	if (dst_reg->u32_max_value > S32_MAX) {
		/* Overflow possible, we know nothing */
		dst_reg->s32_min_value = S32_MIN;
		dst_reg->s32_max_value = S32_MAX;
	} else {
		dst_reg->s32_min_value = dst_reg->u32_min_value;
		dst_reg->s32_max_value = dst_reg->u32_max_value;
	}
}

static void scalar_min_max_mul(struct bpf_reg_state *dst_reg,
			       struct bpf_reg_state *src_reg)
{
	s64 smin_val = src_reg->smin_value;
	u64 umin_val = src_reg->umin_value;
	u64 umax_val = src_reg->umax_value;

	if (smin_val < 0 || dst_reg->smin_value < 0) {
		/* Ain't nobody got time to multiply that sign */
		__mark_reg64_unbounded(dst_reg);
		return;
	}
	/* Both values are positive, so we can work with unsigned and
	 * copy the result to signed (unless it exceeds S64_MAX).
	 */
	if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) {
		/* Potential overflow, we know nothing */
		__mark_reg64_unbounded(dst_reg);
		return;
	}
	dst_reg->umin_value *= umin_val;
	dst_reg->umax_value *= umax_val;
	if (dst_reg->umax_value > S64_MAX) {
		/* Overflow possible, we know nothing */
		dst_reg->smin_value = S64_MIN;
		dst_reg->smax_value = S64_MAX;
	} else {
		dst_reg->smin_value = dst_reg->umin_value;
		dst_reg->smax_value = dst_reg->umax_value;
	}
}

static void scalar32_min_max_and(struct bpf_reg_state *dst_reg,
				 struct bpf_reg_state *src_reg)
{
	bool src_known = tnum_subreg_is_const(src_reg->var_off);
	bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
	struct tnum var32_off = tnum_subreg(dst_reg->var_off);
	u32 umax_val = src_reg->u32_max_value;

	if (src_known && dst_known) {
		__mark_reg32_known(dst_reg, var32_off.value);
		return;
	}

	/* We get our minimum from the var_off, since that's inherently
	 * bitwise.  Our maximum is the minimum of the operands' maxima.
	 */
	dst_reg->u32_min_value = var32_off.value;
	dst_reg->u32_max_value = min(dst_reg->u32_max_value, umax_val);

	/* Safe to set s32 bounds by casting u32 result into s32 when u32
	 * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
	 */
	if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
		dst_reg->s32_min_value = dst_reg->u32_min_value;
		dst_reg->s32_max_value = dst_reg->u32_max_value;
	} else {
		dst_reg->s32_min_value = S32_MIN;
		dst_reg->s32_max_value = S32_MAX;
	}
}

static void scalar_min_max_and(struct bpf_reg_state *dst_reg,
			       struct bpf_reg_state *src_reg)
{
	bool src_known = tnum_is_const(src_reg->var_off);
	bool dst_known = tnum_is_const(dst_reg->var_off);
	u64 umax_val = src_reg->umax_value;

	if (src_known && dst_known) {
		__mark_reg_known(dst_reg, dst_reg->var_off.value);
		return;
	}

	/* We get our minimum from the var_off, since that's inherently
	 * bitwise.  Our maximum is the minimum of the operands' maxima.
	 */
	dst_reg->umin_value = dst_reg->var_off.value;
	dst_reg->umax_value = min(dst_reg->umax_value, umax_val);

	/* Safe to set s64 bounds by casting u64 result into s64 when u64
	 * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
	 */
	if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
		dst_reg->smin_value = dst_reg->umin_value;
		dst_reg->smax_value = dst_reg->umax_value;
	} else {
		dst_reg->smin_value = S64_MIN;
		dst_reg->smax_value = S64_MAX;
	}
	/* We may learn something more from the var_off */
	__update_reg_bounds(dst_reg);
}

static void scalar32_min_max_or(struct bpf_reg_state *dst_reg,
				struct bpf_reg_state *src_reg)
{
	bool src_known = tnum_subreg_is_const(src_reg->var_off);
	bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
	struct tnum var32_off = tnum_subreg(dst_reg->var_off);
	u32 umin_val = src_reg->u32_min_value;

	if (src_known && dst_known) {
		__mark_reg32_known(dst_reg, var32_off.value);
		return;
	}

	/* We get our maximum from the var_off, and our minimum is the
	 * maximum of the operands' minima
	 */
	dst_reg->u32_min_value = max(dst_reg->u32_min_value, umin_val);
	dst_reg->u32_max_value = var32_off.value | var32_off.mask;

	/* Safe to set s32 bounds by casting u32 result into s32 when u32
	 * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
	 */
	if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
		dst_reg->s32_min_value = dst_reg->u32_min_value;
		dst_reg->s32_max_value = dst_reg->u32_max_value;
	} else {
		dst_reg->s32_min_value = S32_MIN;
		dst_reg->s32_max_value = S32_MAX;
	}
}

static void scalar_min_max_or(struct bpf_reg_state *dst_reg,
			      struct bpf_reg_state *src_reg)
{
	bool src_known = tnum_is_const(src_reg->var_off);
	bool dst_known = tnum_is_const(dst_reg->var_off);
	u64 umin_val = src_reg->umin_value;

	if (src_known && dst_known) {
		__mark_reg_known(dst_reg, dst_reg->var_off.value);
		return;
	}

	/* We get our maximum from the var_off, and our minimum is the
	 * maximum of the operands' minima
	 */
	dst_reg->umin_value = max(dst_reg->umin_value, umin_val);
	dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;

	/* Safe to set s64 bounds by casting u64 result into s64 when u64
	 * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
	 */
	if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
		dst_reg->smin_value = dst_reg->umin_value;
		dst_reg->smax_value = dst_reg->umax_value;
	} else {
		dst_reg->smin_value = S64_MIN;
		dst_reg->smax_value = S64_MAX;
	}
	/* We may learn something more from the var_off */
	__update_reg_bounds(dst_reg);
}

static void scalar32_min_max_xor(struct bpf_reg_state *dst_reg,
				 struct bpf_reg_state *src_reg)
{
	bool src_known = tnum_subreg_is_const(src_reg->var_off);
	bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
	struct tnum var32_off = tnum_subreg(dst_reg->var_off);

	if (src_known && dst_known) {
		__mark_reg32_known(dst_reg, var32_off.value);
		return;
	}

	/* We get both minimum and maximum from the var32_off. */
	dst_reg->u32_min_value = var32_off.value;
	dst_reg->u32_max_value = var32_off.value | var32_off.mask;

	/* Safe to set s32 bounds by casting u32 result into s32 when u32
	 * doesn't cross sign boundary. Otherwise set s32 bounds to unbounded.
	 */
	if ((s32)dst_reg->u32_min_value <= (s32)dst_reg->u32_max_value) {
		dst_reg->s32_min_value = dst_reg->u32_min_value;
		dst_reg->s32_max_value = dst_reg->u32_max_value;
	} else {
		dst_reg->s32_min_value = S32_MIN;
		dst_reg->s32_max_value = S32_MAX;
	}
}

static void scalar_min_max_xor(struct bpf_reg_state *dst_reg,
			       struct bpf_reg_state *src_reg)
{
	bool src_known = tnum_is_const(src_reg->var_off);
	bool dst_known = tnum_is_const(dst_reg->var_off);

	if (src_known && dst_known) {
		/* dst_reg->var_off.value has been updated earlier */
		__mark_reg_known(dst_reg, dst_reg->var_off.value);
		return;
	}

	/* We get both minimum and maximum from the var_off. */
	dst_reg->umin_value = dst_reg->var_off.value;
	dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;

	/* Safe to set s64 bounds by casting u64 result into s64 when u64
	 * doesn't cross sign boundary. Otherwise set s64 bounds to unbounded.
	 */
	if ((s64)dst_reg->umin_value <= (s64)dst_reg->umax_value) {
		dst_reg->smin_value = dst_reg->umin_value;
		dst_reg->smax_value = dst_reg->umax_value;
	} else {
		dst_reg->smin_value = S64_MIN;
		dst_reg->smax_value = S64_MAX;
	}

	__update_reg_bounds(dst_reg);
}

static void __scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
				   u64 umin_val, u64 umax_val)
{
	/* We lose all sign bit information (except what we can pick
	 * up from var_off)
	 */
	dst_reg->s32_min_value = S32_MIN;
	dst_reg->s32_max_value = S32_MAX;
	/* If we might shift our top bit out, then we know nothing */
	if (umax_val > 31 || dst_reg->u32_max_value > 1ULL << (31 - umax_val)) {
		dst_reg->u32_min_value = 0;
		dst_reg->u32_max_value = U32_MAX;
	} else {
		dst_reg->u32_min_value <<= umin_val;
		dst_reg->u32_max_value <<= umax_val;
	}
}

static void scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
				 struct bpf_reg_state *src_reg)
{
	u32 umax_val = src_reg->u32_max_value;
	u32 umin_val = src_reg->u32_min_value;
	/* u32 alu operation will zext upper bits */
	struct tnum subreg = tnum_subreg(dst_reg->var_off);

	__scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
	dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val));
	/* Not required but being careful mark reg64 bounds as unknown so
	 * that we are forced to pick them up from tnum and zext later and
	 * if some path skips this step we are still safe.
	 */
	__mark_reg64_unbounded(dst_reg);
	__update_reg32_bounds(dst_reg);
}

static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg,
				   u64 umin_val, u64 umax_val)
{
	/* Special case <<32 because it is a common compiler pattern to sign
	 * extend subreg by doing <<32 s>>32. In this case if 32bit bounds are
	 * positive we know this shift will also be positive so we can track
	 * bounds correctly. Otherwise we lose all sign bit information except
	 * what we can pick up from var_off. Perhaps we can generalize this
	 * later to shifts of any length.
	 */
	if (umin_val == 32 && umax_val == 32 && dst_reg->s32_max_value >= 0)
		dst_reg->smax_value = (s64)dst_reg->s32_max_value << 32;
	else
		dst_reg->smax_value = S64_MAX;

	if (umin_val == 32 && umax_val == 32 && dst_reg->s32_min_value >= 0)
		dst_reg->smin_value = (s64)dst_reg->s32_min_value << 32;
	else
		dst_reg->smin_value = S64_MIN;

	/* If we might shift our top bit out, then we know nothing */
	if (dst_reg->umax_value > 1ULL << (63 - umax_val)) {
		dst_reg->umin_value = 0;
		dst_reg->umax_value = U64_MAX;
	} else {
		dst_reg->umin_value <<= umin_val;
		dst_reg->umax_value <<= umax_val;
	}
}

static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg,
			       struct bpf_reg_state *src_reg)
{
	u64 umax_val = src_reg->umax_value;
	u64 umin_val = src_reg->umin_value;

	/* scalar64 calc uses 32bit unshifted bounds so must be called first */
	__scalar64_min_max_lsh(dst_reg, umin_val, umax_val);
	__scalar32_min_max_lsh(dst_reg, umin_val, umax_val);

	dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
	/* We may learn something more from the var_off */
	__update_reg_bounds(dst_reg);
}

static void scalar32_min_max_rsh(struct bpf_reg_state *dst_reg,
				 struct bpf_reg_state *src_reg)
{
	struct tnum subreg = tnum_subreg(dst_reg->var_off);
	u32 umax_val = src_reg->u32_max_value;
	u32 umin_val = src_reg->u32_min_value;

	/* BPF_RSH is an unsigned shift.  If the value in dst_reg might
	 * be negative, then either:
	 * 1) src_reg might be zero, so the sign bit of the result is
	 *    unknown, so we lose our signed bounds
	 * 2) it's known negative, thus the unsigned bounds capture the
	 *    signed bounds
	 * 3) the signed bounds cross zero, so they tell us nothing
	 *    about the result
	 * If the value in dst_reg is known nonnegative, then again the
	 * unsigned bounds capture the signed bounds.
	 * Thus, in all cases it suffices to blow away our signed bounds
	 * and rely on inferring new ones from the unsigned bounds and
	 * var_off of the result.
	 */
	dst_reg->s32_min_value = S32_MIN;
	dst_reg->s32_max_value = S32_MAX;

	dst_reg->var_off = tnum_rshift(subreg, umin_val);
	dst_reg->u32_min_value >>= umax_val;
	dst_reg->u32_max_value >>= umin_val;

	__mark_reg64_unbounded(dst_reg);
	__update_reg32_bounds(dst_reg);
}

static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg,
			       struct bpf_reg_state *src_reg)
{
	u64 umax_val = src_reg->umax_value;
	u64 umin_val = src_reg->umin_value;

	/* BPF_RSH is an unsigned shift.  If the value in dst_reg might
	 * be negative, then either:
	 * 1) src_reg might be zero, so the sign bit of the result is
	 *    unknown, so we lose our signed bounds
	 * 2) it's known negative, thus the unsigned bounds capture the
	 *    signed bounds
	 * 3) the signed bounds cross zero, so they tell us nothing
	 *    about the result
	 * If the value in dst_reg is known nonnegative, then again the
	 * unsigned bounds capture the signed bounds.
	 * Thus, in all cases it suffices to blow away our signed bounds
	 * and rely on inferring new ones from the unsigned bounds and
	 * var_off of the result.
	 */
	dst_reg->smin_value = S64_MIN;
	dst_reg->smax_value = S64_MAX;
	dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
	dst_reg->umin_value >>= umax_val;
	dst_reg->umax_value >>= umin_val;

	/* Its not easy to operate on alu32 bounds here because it depends
	 * on bits being shifted in. Take easy way out and mark unbounded
	 * so we can recalculate later from tnum.
	 */
	__mark_reg32_unbounded(dst_reg);
	__update_reg_bounds(dst_reg);
}

static void scalar32_min_max_arsh(struct bpf_reg_state *dst_reg,
				  struct bpf_reg_state *src_reg)
{
	u64 umin_val = src_reg->u32_min_value;

	/* Upon reaching here, src_known is true and
	 * umax_val is equal to umin_val.
	 */
	dst_reg->s32_min_value = (u32)(((s32)dst_reg->s32_min_value) >> umin_val);
	dst_reg->s32_max_value = (u32)(((s32)dst_reg->s32_max_value) >> umin_val);

	dst_reg->var_off = tnum_arshift(tnum_subreg(dst_reg->var_off), umin_val, 32);

	/* blow away the dst_reg umin_value/umax_value and rely on
	 * dst_reg var_off to refine the result.
	 */
	dst_reg->u32_min_value = 0;
	dst_reg->u32_max_value = U32_MAX;

	__mark_reg64_unbounded(dst_reg);
	__update_reg32_bounds(dst_reg);
}

static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg,
				struct bpf_reg_state *src_reg)
{
	u64 umin_val = src_reg->umin_value;

	/* Upon reaching here, src_known is true and umax_val is equal
	 * to umin_val.
	 */
	dst_reg->smin_value >>= umin_val;
	dst_reg->smax_value >>= umin_val;

	dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, 64);

	/* blow away the dst_reg umin_value/umax_value and rely on
	 * dst_reg var_off to refine the result.
	 */
	dst_reg->umin_value = 0;
	dst_reg->umax_value = U64_MAX;

	/* Its not easy to operate on alu32 bounds here because it depends
	 * on bits being shifted in from upper 32-bits. Take easy way out
	 * and mark unbounded so we can recalculate later from tnum.
	 */
	__mark_reg32_unbounded(dst_reg);
	__update_reg_bounds(dst_reg);
}

static bool is_safe_to_compute_dst_reg_range(struct bpf_insn *insn,
					     const struct bpf_reg_state *src_reg)
{
	bool src_is_const = false;
	u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32;

	if (insn_bitness == 32) {
		if (tnum_subreg_is_const(src_reg->var_off)
		    && src_reg->s32_min_value == src_reg->s32_max_value
		    && src_reg->u32_min_value == src_reg->u32_max_value)
			src_is_const = true;
	} else {
		if (tnum_is_const(src_reg->var_off)
		    && src_reg->smin_value == src_reg->smax_value
		    && src_reg->umin_value == src_reg->umax_value)
			src_is_const = true;
	}

	switch (BPF_OP(insn->code)) {
	case BPF_ADD:
	case BPF_SUB:
	case BPF_AND:
	case BPF_XOR:
	case BPF_OR:
	case BPF_MUL:
		return true;

	/* Shift operators range is only computable if shift dimension operand
	 * is a constant. Shifts greater than 31 or 63 are undefined. This
	 * includes shifts by a negative number.
	 */
	case BPF_LSH:
	case BPF_RSH:
	case BPF_ARSH:
		return (src_is_const && src_reg->umax_value < insn_bitness);
	default:
		return false;
	}
}

/* WARNING: This function does calculations on 64-bit values, but the actual
 * execution may occur on 32-bit values. Therefore, things like bitshifts
 * need extra checks in the 32-bit case.
 */
static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
				      struct bpf_insn *insn,
				      struct bpf_reg_state *dst_reg,
				      struct bpf_reg_state src_reg)
{
	u8 opcode = BPF_OP(insn->code);
	bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
	int ret;

	if (!is_safe_to_compute_dst_reg_range(insn, &src_reg)) {
		__mark_reg_unknown(env, dst_reg);
		return 0;
	}

	if (sanitize_needed(opcode)) {
		ret = sanitize_val_alu(env, insn);
		if (ret < 0)
			return sanitize_err(env, insn, ret, NULL, NULL);
	}

	/* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops.
	 * There are two classes of instructions: The first class we track both
	 * alu32 and alu64 sign/unsigned bounds independently this provides the
	 * greatest amount of precision when alu operations are mixed with jmp32
	 * operations. These operations are BPF_ADD, BPF_SUB, BPF_MUL, BPF_ADD,
	 * and BPF_OR. This is possible because these ops have fairly easy to
	 * understand and calculate behavior in both 32-bit and 64-bit alu ops.
	 * See alu32 verifier tests for examples. The second class of
	 * operations, BPF_LSH, BPF_RSH, and BPF_ARSH, however are not so easy
	 * with regards to tracking sign/unsigned bounds because the bits may
	 * cross subreg boundaries in the alu64 case. When this happens we mark
	 * the reg unbounded in the subreg bound space and use the resulting
	 * tnum to calculate an approximation of the sign/unsigned bounds.
	 */
	switch (opcode) {
	case BPF_ADD:
		scalar32_min_max_add(dst_reg, &src_reg);
		scalar_min_max_add(dst_reg, &src_reg);
		dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
		break;
	case BPF_SUB:
		scalar32_min_max_sub(dst_reg, &src_reg);
		scalar_min_max_sub(dst_reg, &src_reg);
		dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off);
		break;
	case BPF_MUL:
		dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off);
		scalar32_min_max_mul(dst_reg, &src_reg);
		scalar_min_max_mul(dst_reg, &src_reg);
		break;
	case BPF_AND:
		dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off);
		scalar32_min_max_and(dst_reg, &src_reg);
		scalar_min_max_and(dst_reg, &src_reg);
		break;
	case BPF_OR:
		dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off);
		scalar32_min_max_or(dst_reg, &src_reg);
		scalar_min_max_or(dst_reg, &src_reg);
		break;
	case BPF_XOR:
		dst_reg->var_off = tnum_xor(dst_reg->var_off, src_reg.var_off);
		scalar32_min_max_xor(dst_reg, &src_reg);
		scalar_min_max_xor(dst_reg, &src_reg);
		break;
	case BPF_LSH:
		if (alu32)
			scalar32_min_max_lsh(dst_reg, &src_reg);
		else
			scalar_min_max_lsh(dst_reg, &src_reg);
		break;
	case BPF_RSH:
		if (alu32)
			scalar32_min_max_rsh(dst_reg, &src_reg);
		else
			scalar_min_max_rsh(dst_reg, &src_reg);
		break;
	case BPF_ARSH:
		if (alu32)
			scalar32_min_max_arsh(dst_reg, &src_reg);
		else
			scalar_min_max_arsh(dst_reg, &src_reg);
		break;
	default:
		break;
	}

	/* ALU32 ops are zero extended into 64bit register */
	if (alu32)
		zext_32_to_64(dst_reg);
	reg_bounds_sync(dst_reg);
	return 0;
}

/* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max
 * and var_off.
 */
static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
				   struct bpf_insn *insn)
{
	struct bpf_verifier_state *vstate = env->cur_state;
	struct bpf_func_state *state = vstate->frame[vstate->curframe];
	struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg;
	struct bpf_reg_state *ptr_reg = NULL, off_reg = {0};
	bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
	u8 opcode = BPF_OP(insn->code);
	int err;

	dst_reg = &regs[insn->dst_reg];
	src_reg = NULL;

	if (dst_reg->type == PTR_TO_ARENA) {
		struct bpf_insn_aux_data *aux = cur_aux(env);

		if (BPF_CLASS(insn->code) == BPF_ALU64)
			/*
			 * 32-bit operations zero upper bits automatically.
			 * 64-bit operations need to be converted to 32.
			 */
			aux->needs_zext = true;

		/* Any arithmetic operations are allowed on arena pointers */
		return 0;
	}

	if (dst_reg->type != SCALAR_VALUE)
		ptr_reg = dst_reg;

	if (BPF_SRC(insn->code) == BPF_X) {
		src_reg = &regs[insn->src_reg];
		if (src_reg->type != SCALAR_VALUE) {
			if (dst_reg->type != SCALAR_VALUE) {
				/* Combining two pointers by any ALU op yields
				 * an arbitrary scalar. Disallow all math except
				 * pointer subtraction
				 */
				if (opcode == BPF_SUB && env->allow_ptr_leaks) {
					mark_reg_unknown(env, regs, insn->dst_reg);
					return 0;
				}
				verbose(env, "R%d pointer %s pointer prohibited\n",
					insn->dst_reg,
					bpf_alu_string[opcode >> 4]);
				return -EACCES;
			} else {
				/* scalar += pointer
				 * This is legal, but we have to reverse our
				 * src/dest handling in computing the range
				 */
				err = mark_chain_precision(env, insn->dst_reg);
				if (err)
					return err;
				return adjust_ptr_min_max_vals(env, insn,
							       src_reg, dst_reg);
			}
		} else if (ptr_reg) {
			/* pointer += scalar */
			err = mark_chain_precision(env, insn->src_reg);
			if (err)
				return err;
			return adjust_ptr_min_max_vals(env, insn,
						       dst_reg, src_reg);
		} else if (dst_reg->precise) {
			/* if dst_reg is precise, src_reg should be precise as well */
			err = mark_chain_precision(env, insn->src_reg);
			if (err)
				return err;
		}
	} else {
		/* Pretend the src is a reg with a known value, since we only
		 * need to be able to read from this state.
		 */
		off_reg.type = SCALAR_VALUE;
		__mark_reg_known(&off_reg, insn->imm);
		src_reg = &off_reg;
		if (ptr_reg) /* pointer += K */
			return adjust_ptr_min_max_vals(env, insn,
						       ptr_reg, src_reg);
	}

	/* Got here implies adding two SCALAR_VALUEs */
	if (WARN_ON_ONCE(ptr_reg)) {
		print_verifier_state(env, state, true);
		verbose(env, "verifier internal error: unexpected ptr_reg\n");
		return -EINVAL;
	}
	if (WARN_ON(!src_reg)) {
		print_verifier_state(env, state, true);
		verbose(env, "verifier internal error: no src_reg\n");
		return -EINVAL;
	}
	err = adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg);
	if (err)
		return err;
	/*
	 * Compilers can generate the code
	 * r1 = r2
	 * r1 += 0x1
	 * if r2 < 1000 goto ...
	 * use r1 in memory access
	 * So for 64-bit alu remember constant delta between r2 and r1 and
	 * update r1 after 'if' condition.
	 */
	if (env->bpf_capable &&
	    BPF_OP(insn->code) == BPF_ADD && !alu32 &&
	    dst_reg->id && is_reg_const(src_reg, false)) {
		u64 val = reg_const_value(src_reg, false);

		if ((dst_reg->id & BPF_ADD_CONST) ||
		    /* prevent overflow in sync_linked_regs() later */
		    val > (u32)S32_MAX) {
			/*
			 * If the register already went through rX += val
			 * we cannot accumulate another val into rx->off.
			 */
			dst_reg->off = 0;
			dst_reg->id = 0;
		} else {
			dst_reg->id |= BPF_ADD_CONST;
			dst_reg->off = val;
		}
	} else {
		/*
		 * Make sure ID is cleared otherwise dst_reg min/max could be
		 * incorrectly propagated into other registers by sync_linked_regs()
		 */
		dst_reg->id = 0;
	}
	return 0;
}

/* check validity of 32-bit and 64-bit arithmetic operations */
static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
{
	struct bpf_reg_state *regs = cur_regs(env);
	u8 opcode = BPF_OP(insn->code);
	int err;

	if (opcode == BPF_END || opcode == BPF_NEG) {
		if (opcode == BPF_NEG) {
			if (BPF_SRC(insn->code) != BPF_K ||
			    insn->src_reg != BPF_REG_0 ||
			    insn->off != 0 || insn->imm != 0) {
				verbose(env, "BPF_NEG uses reserved fields\n");
				return -EINVAL;
			}
		} else {
			if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
			    (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
			    (BPF_CLASS(insn->code) == BPF_ALU64 &&
			     BPF_SRC(insn->code) != BPF_TO_LE)) {
				verbose(env, "BPF_END uses reserved fields\n");
				return -EINVAL;
			}
		}

		/* check src operand */
		err = check_reg_arg(env, insn->dst_reg, SRC_OP);
		if (err)
			return err;

		if (is_pointer_value(env, insn->dst_reg)) {
			verbose(env, "R%d pointer arithmetic prohibited\n",
				insn->dst_reg);
			return -EACCES;
		}

		/* check dest operand */
		err = check_reg_arg(env, insn->dst_reg, DST_OP);
		if (err)
			return err;

	} else if (opcode == BPF_MOV) {

		if (BPF_SRC(insn->code) == BPF_X) {
			if (BPF_CLASS(insn->code) == BPF_ALU) {
				if ((insn->off != 0 && insn->off != 8 && insn->off != 16) ||
				    insn->imm) {
					verbose(env, "BPF_MOV uses reserved fields\n");
					return -EINVAL;
				}
			} else if (insn->off == BPF_ADDR_SPACE_CAST) {
				if (insn->imm != 1 && insn->imm != 1u << 16) {
					verbose(env, "addr_space_cast insn can only convert between address space 1 and 0\n");
					return -EINVAL;
				}
				if (!env->prog->aux->arena) {
					verbose(env, "addr_space_cast insn can only be used in a program that has an associated arena\n");
					return -EINVAL;
				}
			} else {
				if ((insn->off != 0 && insn->off != 8 && insn->off != 16 &&
				     insn->off != 32) || insn->imm) {
					verbose(env, "BPF_MOV uses reserved fields\n");
					return -EINVAL;
				}
			}

			/* check src operand */
			err = check_reg_arg(env, insn->src_reg, SRC_OP);
			if (err)
				return err;
		} else {
			if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
				verbose(env, "BPF_MOV uses reserved fields\n");
				return -EINVAL;
			}
		}

		/* check dest operand, mark as required later */
		err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
		if (err)
			return err;

		if (BPF_SRC(insn->code) == BPF_X) {
			struct bpf_reg_state *src_reg = regs + insn->src_reg;
			struct bpf_reg_state *dst_reg = regs + insn->dst_reg;

			if (BPF_CLASS(insn->code) == BPF_ALU64) {
				if (insn->imm) {
					/* off == BPF_ADDR_SPACE_CAST */
					mark_reg_unknown(env, regs, insn->dst_reg);
					if (insn->imm == 1) { /* cast from as(1) to as(0) */
						dst_reg->type = PTR_TO_ARENA;
						/* PTR_TO_ARENA is 32-bit */
						dst_reg->subreg_def = env->insn_idx + 1;
					}
				} else if (insn->off == 0) {
					/* case: R1 = R2
					 * copy register state to dest reg
					 */
					assign_scalar_id_before_mov(env, src_reg);
					copy_register_state(dst_reg, src_reg);
					dst_reg->live |= REG_LIVE_WRITTEN;
					dst_reg->subreg_def = DEF_NOT_SUBREG;
				} else {
					/* case: R1 = (s8, s16 s32)R2 */
					if (is_pointer_value(env, insn->src_reg)) {
						verbose(env,
							"R%d sign-extension part of pointer\n",
							insn->src_reg);
						return -EACCES;
					} else if (src_reg->type == SCALAR_VALUE) {
						bool no_sext;

						no_sext = src_reg->umax_value < (1ULL << (insn->off - 1));
						if (no_sext)
							assign_scalar_id_before_mov(env, src_reg);
						copy_register_state(dst_reg, src_reg);
						if (!no_sext)
							dst_reg->id = 0;
						coerce_reg_to_size_sx(dst_reg, insn->off >> 3);
						dst_reg->live |= REG_LIVE_WRITTEN;
						dst_reg->subreg_def = DEF_NOT_SUBREG;
					} else {
						mark_reg_unknown(env, regs, insn->dst_reg);
					}
				}
			} else {
				/* R1 = (u32) R2 */
				if (is_pointer_value(env, insn->src_reg)) {
					verbose(env,
						"R%d partial copy of pointer\n",
						insn->src_reg);
					return -EACCES;
				} else if (src_reg->type == SCALAR_VALUE) {
					if (insn->off == 0) {
						bool is_src_reg_u32 = get_reg_width(src_reg) <= 32;

						if (is_src_reg_u32)
							assign_scalar_id_before_mov(env, src_reg);
						copy_register_state(dst_reg, src_reg);
						/* Make sure ID is cleared if src_reg is not in u32
						 * range otherwise dst_reg min/max could be incorrectly
						 * propagated into src_reg by sync_linked_regs()
						 */
						if (!is_src_reg_u32)
							dst_reg->id = 0;
						dst_reg->live |= REG_LIVE_WRITTEN;
						dst_reg->subreg_def = env->insn_idx + 1;
					} else {
						/* case: W1 = (s8, s16)W2 */
						bool no_sext = src_reg->umax_value < (1ULL << (insn->off - 1));

						if (no_sext)
							assign_scalar_id_before_mov(env, src_reg);
						copy_register_state(dst_reg, src_reg);
						if (!no_sext)
							dst_reg->id = 0;
						dst_reg->live |= REG_LIVE_WRITTEN;
						dst_reg->subreg_def = env->insn_idx + 1;
						coerce_subreg_to_size_sx(dst_reg, insn->off >> 3);
					}
				} else {
					mark_reg_unknown(env, regs,
							 insn->dst_reg);
				}
				zext_32_to_64(dst_reg);
				reg_bounds_sync(dst_reg);
			}
		} else {
			/* case: R = imm
			 * remember the value we stored into this reg
			 */
			/* clear any state __mark_reg_known doesn't set */
			mark_reg_unknown(env, regs, insn->dst_reg);
			regs[insn->dst_reg].type = SCALAR_VALUE;
			if (BPF_CLASS(insn->code) == BPF_ALU64) {
				__mark_reg_known(regs + insn->dst_reg,
						 insn->imm);
			} else {
				__mark_reg_known(regs + insn->dst_reg,
						 (u32)insn->imm);
			}
		}

	} else if (opcode > BPF_END) {
		verbose(env, "invalid BPF_ALU opcode %x\n", opcode);
		return -EINVAL;

	} else {	/* all other ALU ops: and, sub, xor, add, ... */

		if (BPF_SRC(insn->code) == BPF_X) {
			if (insn->imm != 0 || insn->off > 1 ||
			    (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) {
				verbose(env, "BPF_ALU uses reserved fields\n");
				return -EINVAL;
			}
			/* check src1 operand */
			err = check_reg_arg(env, insn->src_reg, SRC_OP);
			if (err)
				return err;
		} else {
			if (insn->src_reg != BPF_REG_0 || insn->off > 1 ||
			    (insn->off == 1 && opcode != BPF_MOD && opcode != BPF_DIV)) {
				verbose(env, "BPF_ALU uses reserved fields\n");
				return -EINVAL;
			}
		}

		/* check src2 operand */
		err = check_reg_arg(env, insn->dst_reg, SRC_OP);
		if (err)
			return err;

		if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
		    BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
			verbose(env, "div by zero\n");
			return -EINVAL;
		}

		if ((opcode == BPF_LSH || opcode == BPF_RSH ||
		     opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
			int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;

			if (insn->imm < 0 || insn->imm >= size) {
				verbose(env, "invalid shift %d\n", insn->imm);
				return -EINVAL;
			}
		}

		/* check dest operand */
		err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
		err = err ?: adjust_reg_min_max_vals(env, insn);
		if (err)
			return err;
	}

	return reg_bounds_sanity_check(env, &regs[insn->dst_reg], "alu");
}

static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
				   struct bpf_reg_state *dst_reg,
				   enum bpf_reg_type type,
				   bool range_right_open)
{
	struct bpf_func_state *state;
	struct bpf_reg_state *reg;
	int new_range;

	if (dst_reg->off < 0 ||
	    (dst_reg->off == 0 && range_right_open))
		/* This doesn't give us any range */
		return;

	if (dst_reg->umax_value > MAX_PACKET_OFF ||
	    dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF)
		/* Risk of overflow.  For instance, ptr + (1<<63) may be less
		 * than pkt_end, but that's because it's also less than pkt.
		 */
		return;

	new_range = dst_reg->off;
	if (range_right_open)
		new_range++;

	/* Examples for register markings:
	 *
	 * pkt_data in dst register:
	 *
	 *   r2 = r3;
	 *   r2 += 8;
	 *   if (r2 > pkt_end) goto <handle exception>
	 *   <access okay>
	 *
	 *   r2 = r3;
	 *   r2 += 8;
	 *   if (r2 < pkt_end) goto <access okay>
	 *   <handle exception>
	 *
	 *   Where:
	 *     r2 == dst_reg, pkt_end == src_reg
	 *     r2=pkt(id=n,off=8,r=0)
	 *     r3=pkt(id=n,off=0,r=0)
	 *
	 * pkt_data in src register:
	 *
	 *   r2 = r3;
	 *   r2 += 8;
	 *   if (pkt_end >= r2) goto <access okay>
	 *   <handle exception>
	 *
	 *   r2 = r3;
	 *   r2 += 8;
	 *   if (pkt_end <= r2) goto <handle exception>
	 *   <access okay>
	 *
	 *   Where:
	 *     pkt_end == dst_reg, r2 == src_reg
	 *     r2=pkt(id=n,off=8,r=0)
	 *     r3=pkt(id=n,off=0,r=0)
	 *
	 * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
	 * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8)
	 * and [r3, r3 + 8-1) respectively is safe to access depending on
	 * the check.
	 */

	/* If our ids match, then we must have the same max_value.  And we
	 * don't care about the other reg's fixed offset, since if it's too big
	 * the range won't allow anything.
	 * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
	 */
	bpf_for_each_reg_in_vstate(vstate, state, reg, ({
		if (reg->type == type && reg->id == dst_reg->id)
			/* keep the maximum range already checked */
			reg->range = max(reg->range, new_range);
	}));
}

/*
 * <reg1> <op> <reg2>, currently assuming reg2 is a constant
 */
static int is_scalar_branch_taken(struct bpf_reg_state *reg1, struct bpf_reg_state *reg2,
				  u8 opcode, bool is_jmp32)
{
	struct tnum t1 = is_jmp32 ? tnum_subreg(reg1->var_off) : reg1->var_off;
	struct tnum t2 = is_jmp32 ? tnum_subreg(reg2->var_off) : reg2->var_off;
	u64 umin1 = is_jmp32 ? (u64)reg1->u32_min_value : reg1->umin_value;
	u64 umax1 = is_jmp32 ? (u64)reg1->u32_max_value : reg1->umax_value;
	s64 smin1 = is_jmp32 ? (s64)reg1->s32_min_value : reg1->smin_value;
	s64 smax1 = is_jmp32 ? (s64)reg1->s32_max_value : reg1->smax_value;
	u64 umin2 = is_jmp32 ? (u64)reg2->u32_min_value : reg2->umin_value;
	u64 umax2 = is_jmp32 ? (u64)reg2->u32_max_value : reg2->umax_value;
	s64 smin2 = is_jmp32 ? (s64)reg2->s32_min_value : reg2->smin_value;
	s64 smax2 = is_jmp32 ? (s64)reg2->s32_max_value : reg2->smax_value;

	switch (opcode) {
	case BPF_JEQ:
		/* constants, umin/umax and smin/smax checks would be
		 * redundant in this case because they all should match
		 */
		if (tnum_is_const(t1) && tnum_is_const(t2))
			return t1.value == t2.value;
		/* non-overlapping ranges */
		if (umin1 > umax2 || umax1 < umin2)
			return 0;
		if (smin1 > smax2 || smax1 < smin2)
			return 0;
		if (!is_jmp32) {
			/* if 64-bit ranges are inconclusive, see if we can
			 * utilize 32-bit subrange knowledge to eliminate
			 * branches that can't be taken a priori
			 */
			if (reg1->u32_min_value > reg2->u32_max_value ||
			    reg1->u32_max_value < reg2->u32_min_value)
				return 0;
			if (reg1->s32_min_value > reg2->s32_max_value ||
			    reg1->s32_max_value < reg2->s32_min_value)
				return 0;
		}
		break;
	case BPF_JNE:
		/* constants, umin/umax and smin/smax checks would be
		 * redundant in this case because they all should match
		 */
		if (tnum_is_const(t1) && tnum_is_const(t2))
			return t1.value != t2.value;
		/* non-overlapping ranges */
		if (umin1 > umax2 || umax1 < umin2)
			return 1;
		if (smin1 > smax2 || smax1 < smin2)
			return 1;
		if (!is_jmp32) {
			/* if 64-bit ranges are inconclusive, see if we can
			 * utilize 32-bit subrange knowledge to eliminate
			 * branches that can't be taken a priori
			 */
			if (reg1->u32_min_value > reg2->u32_max_value ||
			    reg1->u32_max_value < reg2->u32_min_value)
				return 1;
			if (reg1->s32_min_value > reg2->s32_max_value ||
			    reg1->s32_max_value < reg2->s32_min_value)
				return 1;
		}
		break;
	case BPF_JSET:
		if (!is_reg_const(reg2, is_jmp32)) {
			swap(reg1, reg2);
			swap(t1, t2);
		}
		if (!is_reg_const(reg2, is_jmp32))
			return -1;
		if ((~t1.mask & t1.value) & t2.value)
			return 1;
		if (!((t1.mask | t1.value) & t2.value))
			return 0;
		break;
	case BPF_JGT:
		if (umin1 > umax2)
			return 1;
		else if (umax1 <= umin2)
			return 0;
		break;
	case BPF_JSGT:
		if (smin1 > smax2)
			return 1;
		else if (smax1 <= smin2)
			return 0;
		break;
	case BPF_JLT:
		if (umax1 < umin2)
			return 1;
		else if (umin1 >= umax2)
			return 0;
		break;
	case BPF_JSLT:
		if (smax1 < smin2)
			return 1;
		else if (smin1 >= smax2)
			return 0;
		break;
	case BPF_JGE:
		if (umin1 >= umax2)
			return 1;
		else if (umax1 < umin2)
			return 0;
		break;
	case BPF_JSGE:
		if (smin1 >= smax2)
			return 1;
		else if (smax1 < smin2)
			return 0;
		break;
	case BPF_JLE:
		if (umax1 <= umin2)
			return 1;
		else if (umin1 > umax2)
			return 0;
		break;
	case BPF_JSLE:
		if (smax1 <= smin2)
			return 1;
		else if (smin1 > smax2)
			return 0;
		break;
	}

	return -1;
}

static int flip_opcode(u32 opcode)
{
	/* How can we transform "a <op> b" into "b <op> a"? */
	static const u8 opcode_flip[16] = {
		/* these stay the same */
		[BPF_JEQ  >> 4] = BPF_JEQ,
		[BPF_JNE  >> 4] = BPF_JNE,
		[BPF_JSET >> 4] = BPF_JSET,
		/* these swap "lesser" and "greater" (L and G in the opcodes) */
		[BPF_JGE  >> 4] = BPF_JLE,
		[BPF_JGT  >> 4] = BPF_JLT,
		[BPF_JLE  >> 4] = BPF_JGE,
		[BPF_JLT  >> 4] = BPF_JGT,
		[BPF_JSGE >> 4] = BPF_JSLE,
		[BPF_JSGT >> 4] = BPF_JSLT,
		[BPF_JSLE