| /* SPDX-License-Identifier: GPL-2.0-only */ |
| /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com |
| */ |
| #ifndef _LINUX_BPF_VERIFIER_H |
| #define _LINUX_BPF_VERIFIER_H 1 |
| |
| #include <linux/bpf.h> /* for enum bpf_reg_type */ |
| #include <linux/filter.h> /* for MAX_BPF_STACK */ |
| #include <linux/tnum.h> |
| |
| /* Maximum variable offset umax_value permitted when resolving memory accesses. |
| * In practice this is far bigger than any realistic pointer offset; this limit |
| * ensures that umax_value + (int)off + (int)size cannot overflow a u64. |
| */ |
| #define BPF_MAX_VAR_OFF (1 << 29) |
| /* Maximum variable size permitted for ARG_CONST_SIZE[_OR_ZERO]. This ensures |
| * that converting umax_value to int cannot overflow. |
| */ |
| #define BPF_MAX_VAR_SIZ (1 << 29) |
| |
| /* Liveness marks, used for registers and spilled-regs (in stack slots). |
| * Read marks propagate upwards until they find a write mark; they record that |
| * "one of this state's descendants read this reg" (and therefore the reg is |
| * relevant for states_equal() checks). |
| * Write marks collect downwards and do not propagate; they record that "the |
| * straight-line code that reached this state (from its parent) wrote this reg" |
| * (and therefore that reads propagated from this state or its descendants |
| * should not propagate to its parent). |
| * A state with a write mark can receive read marks; it just won't propagate |
| * them to its parent, since the write mark is a property, not of the state, |
| * but of the link between it and its parent. See mark_reg_read() and |
| * mark_stack_slot_read() in kernel/bpf/verifier.c. |
| */ |
| enum bpf_reg_liveness { |
| REG_LIVE_NONE = 0, /* reg hasn't been read or written this branch */ |
| REG_LIVE_READ32 = 0x1, /* reg was read, so we're sensitive to initial value */ |
| REG_LIVE_READ64 = 0x2, /* likewise, but full 64-bit content matters */ |
| REG_LIVE_READ = REG_LIVE_READ32 | REG_LIVE_READ64, |
| REG_LIVE_WRITTEN = 0x4, /* reg was written first, screening off later reads */ |
| REG_LIVE_DONE = 0x8, /* liveness won't be updating this register anymore */ |
| }; |
| |
| struct bpf_reg_state { |
| /* Ordering of fields matters. See states_equal() */ |
| enum bpf_reg_type type; |
| union { |
| /* valid when type == PTR_TO_PACKET */ |
| u16 range; |
| |
| /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE | |
| * PTR_TO_MAP_VALUE_OR_NULL |
| */ |
| struct bpf_map *map_ptr; |
| |
| /* Max size from any of the above. */ |
| unsigned long raw; |
| }; |
| /* Fixed part of pointer offset, pointer types only */ |
| s32 off; |
| /* For PTR_TO_PACKET, used to find other pointers with the same variable |
| * offset, so they can share range knowledge. |
| * For PTR_TO_MAP_VALUE_OR_NULL this is used to share which map value we |
| * came from, when one is tested for != NULL. |
| * For PTR_TO_SOCKET this is used to share which pointers retain the |
| * same reference to the socket, to determine proper reference freeing. |
| */ |
| u32 id; |
| /* PTR_TO_SOCKET and PTR_TO_TCP_SOCK could be a ptr returned |
| * from a pointer-cast helper, bpf_sk_fullsock() and |
| * bpf_tcp_sock(). |
| * |
| * Consider the following where "sk" is a reference counted |
| * pointer returned from "sk = bpf_sk_lookup_tcp();": |
| * |
| * 1: sk = bpf_sk_lookup_tcp(); |
| * 2: if (!sk) { return 0; } |
| * 3: fullsock = bpf_sk_fullsock(sk); |
| * 4: if (!fullsock) { bpf_sk_release(sk); return 0; } |
| * 5: tp = bpf_tcp_sock(fullsock); |
| * 6: if (!tp) { bpf_sk_release(sk); return 0; } |
| * 7: bpf_sk_release(sk); |
| * 8: snd_cwnd = tp->snd_cwnd; // verifier will complain |
| * |
| * After bpf_sk_release(sk) at line 7, both "fullsock" ptr and |
| * "tp" ptr should be invalidated also. In order to do that, |
| * the reg holding "fullsock" and "sk" need to remember |
| * the original refcounted ptr id (i.e. sk_reg->id) in ref_obj_id |
| * such that the verifier can reset all regs which have |
| * ref_obj_id matching the sk_reg->id. |
| * |
| * sk_reg->ref_obj_id is set to sk_reg->id at line 1. |
| * sk_reg->id will stay as NULL-marking purpose only. |
| * After NULL-marking is done, sk_reg->id can be reset to 0. |
| * |
| * After "fullsock = bpf_sk_fullsock(sk);" at line 3, |
| * fullsock_reg->ref_obj_id is set to sk_reg->ref_obj_id. |
| * |
| * After "tp = bpf_tcp_sock(fullsock);" at line 5, |
| * tp_reg->ref_obj_id is set to fullsock_reg->ref_obj_id |
| * which is the same as sk_reg->ref_obj_id. |
| * |
| * From the verifier perspective, if sk, fullsock and tp |
| * are not NULL, they are the same ptr with different |
| * reg->type. In particular, bpf_sk_release(tp) is also |
| * allowed and has the same effect as bpf_sk_release(sk). |
| */ |
| u32 ref_obj_id; |
| /* For scalar types (SCALAR_VALUE), this represents our knowledge of |
| * the actual value. |
| * For pointer types, this represents the variable part of the offset |
| * from the pointed-to object, and is shared with all bpf_reg_states |
| * with the same id as us. |
| */ |
| struct tnum var_off; |
| /* Used to determine if any memory access using this register will |
| * result in a bad access. |
| * These refer to the same value as var_off, not necessarily the actual |
| * contents of the register. |
| */ |
| s64 smin_value; /* minimum possible (s64)value */ |
| s64 smax_value; /* maximum possible (s64)value */ |
| u64 umin_value; /* minimum possible (u64)value */ |
| u64 umax_value; /* maximum possible (u64)value */ |
| /* parentage chain for liveness checking */ |
| struct bpf_reg_state *parent; |
| /* Inside the callee two registers can be both PTR_TO_STACK like |
| * R1=fp-8 and R2=fp-8, but one of them points to this function stack |
| * while another to the caller's stack. To differentiate them 'frameno' |
| * is used which is an index in bpf_verifier_state->frame[] array |
| * pointing to bpf_func_state. |
| */ |
| u32 frameno; |
| /* Tracks subreg definition. The stored value is the insn_idx of the |
| * writing insn. This is safe because subreg_def is used before any insn |
| * patching which only happens after main verification finished. |
| */ |
| s32 subreg_def; |
| enum bpf_reg_liveness live; |
| /* if (!precise && SCALAR_VALUE) min/max/tnum don't affect safety */ |
| bool precise; |
| }; |
| |
| enum bpf_stack_slot_type { |
| STACK_INVALID, /* nothing was stored in this stack slot */ |
| STACK_SPILL, /* register spilled into stack */ |
| STACK_MISC, /* BPF program wrote some data into this slot */ |
| STACK_ZERO, /* BPF program wrote constant zero */ |
| }; |
| |
| #define BPF_REG_SIZE 8 /* size of eBPF register in bytes */ |
| |
| struct bpf_stack_state { |
| struct bpf_reg_state spilled_ptr; |
| u8 slot_type[BPF_REG_SIZE]; |
| }; |
| |
| struct bpf_reference_state { |
| /* Track each reference created with a unique id, even if the same |
| * instruction creates the reference multiple times (eg, via CALL). |
| */ |
| int id; |
| /* Instruction where the allocation of this reference occurred. This |
| * is used purely to inform the user of a reference leak. |
| */ |
| int insn_idx; |
| }; |
| |
| /* state of the program: |
| * type of all registers and stack info |
| */ |
| struct bpf_func_state { |
| struct bpf_reg_state regs[MAX_BPF_REG]; |
| /* index of call instruction that called into this func */ |
| int callsite; |
| /* stack frame number of this function state from pov of |
| * enclosing bpf_verifier_state. |
| * 0 = main function, 1 = first callee. |
| */ |
| u32 frameno; |
| /* subprog number == index within subprog_stack_depth |
| * zero == main subprog |
| */ |
| u32 subprogno; |
| |
| /* The following fields should be last. See copy_func_state() */ |
| int acquired_refs; |
| struct bpf_reference_state *refs; |
| int allocated_stack; |
| struct bpf_stack_state *stack; |
| }; |
| |
| struct bpf_idx_pair { |
| u32 prev_idx; |
| u32 idx; |
| }; |
| |
| #define MAX_CALL_FRAMES 8 |
| struct bpf_verifier_state { |
| /* call stack tracking */ |
| struct bpf_func_state *frame[MAX_CALL_FRAMES]; |
| struct bpf_verifier_state *parent; |
| /* |
| * 'branches' field is the number of branches left to explore: |
| * 0 - all possible paths from this state reached bpf_exit or |
| * were safely pruned |
| * 1 - at least one path is being explored. |
| * This state hasn't reached bpf_exit |
| * 2 - at least two paths are being explored. |
| * This state is an immediate parent of two children. |
| * One is fallthrough branch with branches==1 and another |
| * state is pushed into stack (to be explored later) also with |
| * branches==1. The parent of this state has branches==1. |
| * The verifier state tree connected via 'parent' pointer looks like: |
| * 1 |
| * 1 |
| * 2 -> 1 (first 'if' pushed into stack) |
| * 1 |
| * 2 -> 1 (second 'if' pushed into stack) |
| * 1 |
| * 1 |
| * 1 bpf_exit. |
| * |
| * Once do_check() reaches bpf_exit, it calls update_branch_counts() |
| * and the verifier state tree will look: |
| * 1 |
| * 1 |
| * 2 -> 1 (first 'if' pushed into stack) |
| * 1 |
| * 1 -> 1 (second 'if' pushed into stack) |
| * 0 |
| * 0 |
| * 0 bpf_exit. |
| * After pop_stack() the do_check() will resume at second 'if'. |
| * |
| * If is_state_visited() sees a state with branches > 0 it means |
| * there is a loop. If such state is exactly equal to the current state |
| * it's an infinite loop. Note states_equal() checks for states |
| * equvalency, so two states being 'states_equal' does not mean |
| * infinite loop. The exact comparison is provided by |
| * states_maybe_looping() function. It's a stronger pre-check and |
| * much faster than states_equal(). |
| * |
| * This algorithm may not find all possible infinite loops or |
| * loop iteration count may be too high. |
| * In such cases BPF_COMPLEXITY_LIMIT_INSNS limit kicks in. |
| */ |
| u32 branches; |
| u32 insn_idx; |
| u32 curframe; |
| u32 active_spin_lock; |
| bool speculative; |
| |
| /* first and last insn idx of this verifier state */ |
| u32 first_insn_idx; |
| u32 last_insn_idx; |
| /* jmp history recorded from first to last. |
| * backtracking is using it to go from last to first. |
| * For most states jmp_history_cnt is [0-3]. |
| * For loops can go up to ~40. |
| */ |
| struct bpf_idx_pair *jmp_history; |
| u32 jmp_history_cnt; |
| }; |
| |
| #define bpf_get_spilled_reg(slot, frame) \ |
| (((slot < frame->allocated_stack / BPF_REG_SIZE) && \ |
| (frame->stack[slot].slot_type[0] == STACK_SPILL)) \ |
| ? &frame->stack[slot].spilled_ptr : NULL) |
| |
| /* Iterate over 'frame', setting 'reg' to either NULL or a spilled register. */ |
| #define bpf_for_each_spilled_reg(iter, frame, reg) \ |
| for (iter = 0, reg = bpf_get_spilled_reg(iter, frame); \ |
| iter < frame->allocated_stack / BPF_REG_SIZE; \ |
| iter++, reg = bpf_get_spilled_reg(iter, frame)) |
| |
| /* linked list of verifier states used to prune search */ |
| struct bpf_verifier_state_list { |
| struct bpf_verifier_state state; |
| struct bpf_verifier_state_list *next; |
| int miss_cnt, hit_cnt; |
| }; |
| |
| /* Possible states for alu_state member. */ |
| #define BPF_ALU_SANITIZE_SRC 1U |
| #define BPF_ALU_SANITIZE_DST 2U |
| #define BPF_ALU_NEG_VALUE (1U << 2) |
| #define BPF_ALU_NON_POINTER (1U << 3) |
| #define BPF_ALU_SANITIZE (BPF_ALU_SANITIZE_SRC | \ |
| BPF_ALU_SANITIZE_DST) |
| |
| struct bpf_insn_aux_data { |
| union { |
| enum bpf_reg_type ptr_type; /* pointer type for load/store insns */ |
| unsigned long map_state; /* pointer/poison value for maps */ |
| s32 call_imm; /* saved imm field of call insn */ |
| u32 alu_limit; /* limit for add/sub register with pointer */ |
| struct { |
| u32 map_index; /* index into used_maps[] */ |
| u32 map_off; /* offset from value base address */ |
| }; |
| }; |
| int ctx_field_size; /* the ctx field size for load insn, maybe 0 */ |
| int sanitize_stack_off; /* stack slot to be cleared */ |
| bool seen; /* this insn was processed by the verifier */ |
| bool zext_dst; /* this insn zero extends dst reg */ |
| u8 alu_state; /* used in combination with alu_limit */ |
| bool prune_point; |
| unsigned int orig_idx; /* original instruction index */ |
| }; |
| |
| #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */ |
| |
| #define BPF_VERIFIER_TMP_LOG_SIZE 1024 |
| |
| struct bpf_verifier_log { |
| u32 level; |
| char kbuf[BPF_VERIFIER_TMP_LOG_SIZE]; |
| char __user *ubuf; |
| u32 len_used; |
| u32 len_total; |
| }; |
| |
| static inline bool bpf_verifier_log_full(const struct bpf_verifier_log *log) |
| { |
| return log->len_used >= log->len_total - 1; |
| } |
| |
| #define BPF_LOG_LEVEL1 1 |
| #define BPF_LOG_LEVEL2 2 |
| #define BPF_LOG_STATS 4 |
| #define BPF_LOG_LEVEL (BPF_LOG_LEVEL1 | BPF_LOG_LEVEL2) |
| #define BPF_LOG_MASK (BPF_LOG_LEVEL | BPF_LOG_STATS) |
| |
| static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log) |
| { |
| return log->level && log->ubuf && !bpf_verifier_log_full(log); |
| } |
| |
| #define BPF_MAX_SUBPROGS 256 |
| |
| struct bpf_subprog_info { |
| u32 start; /* insn idx of function entry point */ |
| u32 linfo_idx; /* The idx to the main_prog->aux->linfo */ |
| u16 stack_depth; /* max. stack depth used by this function */ |
| }; |
| |
| /* single container for all structs |
| * one verifier_env per bpf_check() call |
| */ |
| struct bpf_verifier_env { |
| u32 insn_idx; |
| u32 prev_insn_idx; |
| struct bpf_prog *prog; /* eBPF program being verified */ |
| const struct bpf_verifier_ops *ops; |
| struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */ |
| int stack_size; /* number of states to be processed */ |
| bool strict_alignment; /* perform strict pointer alignment checks */ |
| struct bpf_verifier_state *cur_state; /* current verifier state */ |
| struct bpf_verifier_state_list **explored_states; /* search pruning optimization */ |
| struct bpf_verifier_state_list *free_list; |
| struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ |
| u32 used_map_cnt; /* number of used maps */ |
| u32 id_gen; /* used to generate unique reg IDs */ |
| bool allow_ptr_leaks; |
| bool seen_direct_write; |
| u16 seen_privileged_funcs; |
| struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */ |
| const struct bpf_line_info *prev_linfo; |
| struct bpf_verifier_log log; |
| struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 1]; |
| struct { |
| int *insn_state; |
| int *insn_stack; |
| int cur_stack; |
| } cfg; |
| u32 subprog_cnt; |
| /* number of instructions analyzed by the verifier */ |
| u32 prev_insn_processed, insn_processed; |
| /* number of jmps, calls, exits analyzed so far */ |
| u32 prev_jmps_processed, jmps_processed; |
| /* total verification time */ |
| u64 verification_time; |
| /* maximum number of verifier states kept in 'branching' instructions */ |
| u32 max_states_per_insn; |
| /* total number of allocated verifier states */ |
| u32 total_states; |
| /* some states are freed during program analysis. |
| * this is peak number of states. this number dominates kernel |
| * memory consumption during verification |
| */ |
| u32 peak_states; |
| /* longest register parentage chain walked for liveness marking */ |
| u32 longest_mark_read_walk; |
| }; |
| |
| __printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log *log, |
| const char *fmt, va_list args); |
| __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env, |
| const char *fmt, ...); |
| |
| static inline struct bpf_func_state *cur_func(struct bpf_verifier_env *env) |
| { |
| struct bpf_verifier_state *cur = env->cur_state; |
| |
| return cur->frame[cur->curframe]; |
| } |
| |
| static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env) |
| { |
| return cur_func(env)->regs; |
| } |
| |
| int bpf_prog_offload_verifier_prep(struct bpf_prog *prog); |
| int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env, |
| int insn_idx, int prev_insn_idx); |
| int bpf_prog_offload_finalize(struct bpf_verifier_env *env); |
| void |
| bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off, |
| struct bpf_insn *insn); |
| void |
| bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt); |
| |
| #endif /* _LINUX_BPF_VERIFIER_H */ |