blob: 2c1427074a3bb9ec6aade6a43cd92c21a25acc26 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/* XSKMAP used for AF_XDP sockets
* Copyright(c) 2018 Intel Corporation.
*/
#include <linux/bpf.h>
#include <linux/filter.h>
#include <linux/capability.h>
#include <net/xdp_sock.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/btf_ids.h>
#include "xsk.h"
static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map,
struct xdp_sock __rcu **map_entry)
{
struct xsk_map_node *node;
node = bpf_map_kzalloc(&map->map, sizeof(*node),
GFP_ATOMIC | __GFP_NOWARN);
if (!node)
return ERR_PTR(-ENOMEM);
bpf_map_inc(&map->map);
atomic_inc(&map->count);
node->map = map;
node->map_entry = map_entry;
return node;
}
static void xsk_map_node_free(struct xsk_map_node *node)
{
struct xsk_map *map = node->map;
bpf_map_put(&node->map->map);
kfree(node);
atomic_dec(&map->count);
}
static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node)
{
spin_lock_bh(&xs->map_list_lock);
list_add_tail(&node->node, &xs->map_list);
spin_unlock_bh(&xs->map_list_lock);
}
static void xsk_map_sock_delete(struct xdp_sock *xs,
struct xdp_sock __rcu **map_entry)
{
struct xsk_map_node *n, *tmp;
spin_lock_bh(&xs->map_list_lock);
list_for_each_entry_safe(n, tmp, &xs->map_list, node) {
if (map_entry == n->map_entry) {
list_del(&n->node);
xsk_map_node_free(n);
}
}
spin_unlock_bh(&xs->map_list_lock);
}
static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
{
struct xsk_map *m;
int numa_node;
u64 size;
if (!capable(CAP_NET_ADMIN))
return ERR_PTR(-EPERM);
if (attr->max_entries == 0 || attr->key_size != 4 ||
attr->value_size != 4 ||
attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY))
return ERR_PTR(-EINVAL);
numa_node = bpf_map_attr_numa_node(attr);
size = struct_size(m, xsk_map, attr->max_entries);
m = bpf_map_area_alloc(size, numa_node);
if (!m)
return ERR_PTR(-ENOMEM);
bpf_map_init_from_attr(&m->map, attr);
spin_lock_init(&m->lock);
return &m->map;
}
static u64 xsk_map_mem_usage(const struct bpf_map *map)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
return struct_size(m, xsk_map, map->max_entries) +
(u64)atomic_read(&m->count) * sizeof(struct xsk_map_node);
}
static void xsk_map_free(struct bpf_map *map)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
synchronize_net();
bpf_map_area_free(m);
}
static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
u32 index = key ? *(u32 *)key : U32_MAX;
u32 *next = next_key;
if (index >= m->map.max_entries) {
*next = 0;
return 0;
}
if (index == m->map.max_entries - 1)
return -ENOENT;
*next = index + 1;
return 0;
}
static int xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
{
const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2;
struct bpf_insn *insn = insn_buf;
*insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
*insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
*insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *)));
*insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map));
*insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp);
*insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0);
*insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
*insn++ = BPF_MOV64_IMM(ret, 0);
return insn - insn_buf;
}
/* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
* by local_bh_disable() (from XDP calls inside NAPI). The
* rcu_read_lock_bh_held() below makes lockdep accept both.
*/
static void *__xsk_map_lookup_elem(struct bpf_map *map, u32 key)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
if (key >= map->max_entries)
return NULL;
return rcu_dereference_check(m->xsk_map[key], rcu_read_lock_bh_held());
}
static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
{
return __xsk_map_lookup_elem(map, *(u32 *)key);
}
static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
{
return ERR_PTR(-EOPNOTSUPP);
}
static long xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
u64 map_flags)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
struct xdp_sock __rcu **map_entry;
struct xdp_sock *xs, *old_xs;
u32 i = *(u32 *)key, fd = *(u32 *)value;
struct xsk_map_node *node;
struct socket *sock;
int err;
if (unlikely(map_flags > BPF_EXIST))
return -EINVAL;
if (unlikely(i >= m->map.max_entries))
return -E2BIG;
sock = sockfd_lookup(fd, &err);
if (!sock)
return err;
if (sock->sk->sk_family != PF_XDP) {
sockfd_put(sock);
return -EOPNOTSUPP;
}
xs = (struct xdp_sock *)sock->sk;
map_entry = &m->xsk_map[i];
node = xsk_map_node_alloc(m, map_entry);
if (IS_ERR(node)) {
sockfd_put(sock);
return PTR_ERR(node);
}
spin_lock_bh(&m->lock);
old_xs = rcu_dereference_protected(*map_entry, lockdep_is_held(&m->lock));
if (old_xs == xs) {
err = 0;
goto out;
} else if (old_xs && map_flags == BPF_NOEXIST) {
err = -EEXIST;
goto out;
} else if (!old_xs && map_flags == BPF_EXIST) {
err = -ENOENT;
goto out;
}
xsk_map_sock_add(xs, node);
rcu_assign_pointer(*map_entry, xs);
if (old_xs)
xsk_map_sock_delete(old_xs, map_entry);
spin_unlock_bh(&m->lock);
sockfd_put(sock);
return 0;
out:
spin_unlock_bh(&m->lock);
sockfd_put(sock);
xsk_map_node_free(node);
return err;
}
static long xsk_map_delete_elem(struct bpf_map *map, void *key)
{
struct xsk_map *m = container_of(map, struct xsk_map, map);
struct xdp_sock __rcu **map_entry;
struct xdp_sock *old_xs;
int k = *(u32 *)key;
if (k >= map->max_entries)
return -EINVAL;
spin_lock_bh(&m->lock);
map_entry = &m->xsk_map[k];
old_xs = unrcu_pointer(xchg(map_entry, NULL));
if (old_xs)
xsk_map_sock_delete(old_xs, map_entry);
spin_unlock_bh(&m->lock);
return 0;
}
static long xsk_map_redirect(struct bpf_map *map, u64 index, u64 flags)
{
return __bpf_xdp_redirect_map(map, index, flags, 0,
__xsk_map_lookup_elem);
}
void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
struct xdp_sock __rcu **map_entry)
{
spin_lock_bh(&map->lock);
if (rcu_access_pointer(*map_entry) == xs) {
rcu_assign_pointer(*map_entry, NULL);
xsk_map_sock_delete(xs, map_entry);
}
spin_unlock_bh(&map->lock);
}
static bool xsk_map_meta_equal(const struct bpf_map *meta0,
const struct bpf_map *meta1)
{
return meta0->max_entries == meta1->max_entries &&
bpf_map_meta_equal(meta0, meta1);
}
BTF_ID_LIST_SINGLE(xsk_map_btf_ids, struct, xsk_map)
const struct bpf_map_ops xsk_map_ops = {
.map_meta_equal = xsk_map_meta_equal,
.map_alloc = xsk_map_alloc,
.map_free = xsk_map_free,
.map_get_next_key = xsk_map_get_next_key,
.map_lookup_elem = xsk_map_lookup_elem,
.map_gen_lookup = xsk_map_gen_lookup,
.map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
.map_update_elem = xsk_map_update_elem,
.map_delete_elem = xsk_map_delete_elem,
.map_check_btf = map_check_no_btf,
.map_mem_usage = xsk_map_mem_usage,
.map_btf_id = &xsk_map_btf_ids[0],
.map_redirect = xsk_map_redirect,
};