1 // SPDX-License-Identifier: GPL-2.0
2 /* XSKMAP used for AF_XDP sockets
3 * Copyright(c) 2018 Intel Corporation.
7 #include <linux/filter.h>
8 #include <linux/capability.h>
9 #include <net/xdp_sock.h>
10 #include <linux/slab.h>
11 #include <linux/sched.h>
12 #include <linux/btf_ids.h>
16 static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map,
17 struct xdp_sock __rcu **map_entry)
19 struct xsk_map_node *node;
21 node = bpf_map_kzalloc(&map->map, sizeof(*node),
22 GFP_ATOMIC | __GFP_NOWARN);
24 return ERR_PTR(-ENOMEM);
26 bpf_map_inc(&map->map);
27 atomic_inc(&map->count);
30 node->map_entry = map_entry;
34 static void xsk_map_node_free(struct xsk_map_node *node)
36 struct xsk_map *map = node->map;
38 bpf_map_put(&node->map->map);
40 atomic_dec(&map->count);
43 static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node)
45 spin_lock_bh(&xs->map_list_lock);
46 list_add_tail(&node->node, &xs->map_list);
47 spin_unlock_bh(&xs->map_list_lock);
50 static void xsk_map_sock_delete(struct xdp_sock *xs,
51 struct xdp_sock __rcu **map_entry)
53 struct xsk_map_node *n, *tmp;
55 spin_lock_bh(&xs->map_list_lock);
56 list_for_each_entry_safe(n, tmp, &xs->map_list, node) {
57 if (map_entry == n->map_entry) {
62 spin_unlock_bh(&xs->map_list_lock);
65 static struct bpf_map *xsk_map_alloc(union bpf_attr *attr)
71 if (!capable(CAP_NET_ADMIN))
72 return ERR_PTR(-EPERM);
74 if (attr->max_entries == 0 || attr->key_size != 4 ||
75 attr->value_size != 4 ||
76 attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY))
77 return ERR_PTR(-EINVAL);
79 numa_node = bpf_map_attr_numa_node(attr);
80 size = struct_size(m, xsk_map, attr->max_entries);
82 m = bpf_map_area_alloc(size, numa_node);
84 return ERR_PTR(-ENOMEM);
86 bpf_map_init_from_attr(&m->map, attr);
87 spin_lock_init(&m->lock);
92 static u64 xsk_map_mem_usage(const struct bpf_map *map)
94 struct xsk_map *m = container_of(map, struct xsk_map, map);
96 return struct_size(m, xsk_map, map->max_entries) +
97 (u64)atomic_read(&m->count) * sizeof(struct xsk_map_node);
100 static void xsk_map_free(struct bpf_map *map)
102 struct xsk_map *m = container_of(map, struct xsk_map, map);
105 bpf_map_area_free(m);
108 static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
110 struct xsk_map *m = container_of(map, struct xsk_map, map);
111 u32 index = key ? *(u32 *)key : U32_MAX;
112 u32 *next = next_key;
114 if (index >= m->map.max_entries) {
119 if (index == m->map.max_entries - 1)
125 static int xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
127 const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2;
128 struct bpf_insn *insn = insn_buf;
130 *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
131 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
132 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *)));
133 *insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map));
134 *insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp);
135 *insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0);
136 *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
137 *insn++ = BPF_MOV64_IMM(ret, 0);
138 return insn - insn_buf;
141 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or
142 * by local_bh_disable() (from XDP calls inside NAPI). The
143 * rcu_read_lock_bh_held() below makes lockdep accept both.
145 static void *__xsk_map_lookup_elem(struct bpf_map *map, u32 key)
147 struct xsk_map *m = container_of(map, struct xsk_map, map);
149 if (key >= map->max_entries)
152 return rcu_dereference_check(m->xsk_map[key], rcu_read_lock_bh_held());
155 static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
157 return __xsk_map_lookup_elem(map, *(u32 *)key);
160 static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
162 return ERR_PTR(-EOPNOTSUPP);
165 static long xsk_map_update_elem(struct bpf_map *map, void *key, void *value,
168 struct xsk_map *m = container_of(map, struct xsk_map, map);
169 struct xdp_sock __rcu **map_entry;
170 struct xdp_sock *xs, *old_xs;
171 u32 i = *(u32 *)key, fd = *(u32 *)value;
172 struct xsk_map_node *node;
176 if (unlikely(map_flags > BPF_EXIST))
178 if (unlikely(i >= m->map.max_entries))
181 sock = sockfd_lookup(fd, &err);
185 if (sock->sk->sk_family != PF_XDP) {
190 xs = (struct xdp_sock *)sock->sk;
192 map_entry = &m->xsk_map[i];
193 node = xsk_map_node_alloc(m, map_entry);
196 return PTR_ERR(node);
199 spin_lock_bh(&m->lock);
200 old_xs = rcu_dereference_protected(*map_entry, lockdep_is_held(&m->lock));
204 } else if (old_xs && map_flags == BPF_NOEXIST) {
207 } else if (!old_xs && map_flags == BPF_EXIST) {
211 xsk_map_sock_add(xs, node);
212 rcu_assign_pointer(*map_entry, xs);
214 xsk_map_sock_delete(old_xs, map_entry);
215 spin_unlock_bh(&m->lock);
220 spin_unlock_bh(&m->lock);
222 xsk_map_node_free(node);
226 static long xsk_map_delete_elem(struct bpf_map *map, void *key)
228 struct xsk_map *m = container_of(map, struct xsk_map, map);
229 struct xdp_sock __rcu **map_entry;
230 struct xdp_sock *old_xs;
233 if (k >= map->max_entries)
236 spin_lock_bh(&m->lock);
237 map_entry = &m->xsk_map[k];
238 old_xs = unrcu_pointer(xchg(map_entry, NULL));
240 xsk_map_sock_delete(old_xs, map_entry);
241 spin_unlock_bh(&m->lock);
246 static long xsk_map_redirect(struct bpf_map *map, u64 index, u64 flags)
248 return __bpf_xdp_redirect_map(map, index, flags, 0,
249 __xsk_map_lookup_elem);
252 void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs,
253 struct xdp_sock __rcu **map_entry)
255 spin_lock_bh(&map->lock);
256 if (rcu_access_pointer(*map_entry) == xs) {
257 rcu_assign_pointer(*map_entry, NULL);
258 xsk_map_sock_delete(xs, map_entry);
260 spin_unlock_bh(&map->lock);
263 static bool xsk_map_meta_equal(const struct bpf_map *meta0,
264 const struct bpf_map *meta1)
266 return meta0->max_entries == meta1->max_entries &&
267 bpf_map_meta_equal(meta0, meta1);
270 BTF_ID_LIST_SINGLE(xsk_map_btf_ids, struct, xsk_map)
271 const struct bpf_map_ops xsk_map_ops = {
272 .map_meta_equal = xsk_map_meta_equal,
273 .map_alloc = xsk_map_alloc,
274 .map_free = xsk_map_free,
275 .map_get_next_key = xsk_map_get_next_key,
276 .map_lookup_elem = xsk_map_lookup_elem,
277 .map_gen_lookup = xsk_map_gen_lookup,
278 .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
279 .map_update_elem = xsk_map_update_elem,
280 .map_delete_elem = xsk_map_delete_elem,
281 .map_check_btf = map_check_no_btf,
282 .map_mem_usage = xsk_map_mem_usage,
283 .map_btf_id = &xsk_map_btf_ids[0],
284 .map_redirect = xsk_map_redirect,