1 // SPDX-License-Identifier: GPL-2.0 2 /* XSKMAP used for AF_XDP sockets 3 * Copyright(c) 2018 Intel Corporation. 4 */ 5 6 #include <linux/bpf.h> 7 #include <linux/filter.h> 8 #include <net/xdp_sock.h> 9 #include <linux/slab.h> 10 #include <linux/sched.h> 11 #include <linux/btf_ids.h> 12 13 #include "xsk.h" 14 15 static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map, 16 struct xdp_sock __rcu **map_entry) 17 { 18 struct xsk_map_node *node; 19 20 node = bpf_map_kzalloc(&map->map, sizeof(*node), 21 GFP_ATOMIC | __GFP_NOWARN); 22 if (!node) 23 return ERR_PTR(-ENOMEM); 24 25 bpf_map_inc(&map->map); 26 atomic_inc(&map->count); 27 28 node->map = map; 29 node->map_entry = map_entry; 30 return node; 31 } 32 33 static void xsk_map_node_free(struct xsk_map_node *node) 34 { 35 struct xsk_map *map = node->map; 36 37 bpf_map_put(&node->map->map); 38 kfree(node); 39 atomic_dec(&map->count); 40 } 41 42 static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node) 43 { 44 spin_lock_bh(&xs->map_list_lock); 45 list_add_tail(&node->node, &xs->map_list); 46 spin_unlock_bh(&xs->map_list_lock); 47 } 48 49 static void xsk_map_sock_delete(struct xdp_sock *xs, 50 struct xdp_sock __rcu **map_entry) 51 { 52 struct xsk_map_node *n, *tmp; 53 54 spin_lock_bh(&xs->map_list_lock); 55 list_for_each_entry_safe(n, tmp, &xs->map_list, node) { 56 if (map_entry == n->map_entry) { 57 list_del(&n->node); 58 xsk_map_node_free(n); 59 } 60 } 61 spin_unlock_bh(&xs->map_list_lock); 62 } 63 64 static struct bpf_map *xsk_map_alloc(union bpf_attr *attr) 65 { 66 struct xsk_map *m; 67 int numa_node; 68 u64 size; 69 70 if (attr->max_entries == 0 || attr->key_size != 4 || 71 attr->value_size != 4 || 72 attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)) 73 return ERR_PTR(-EINVAL); 74 75 numa_node = bpf_map_attr_numa_node(attr); 76 size = struct_size(m, xsk_map, attr->max_entries); 77 78 m = bpf_map_area_alloc(size, numa_node); 79 if (!m) 80 return ERR_PTR(-ENOMEM); 81 82 bpf_map_init_from_attr(&m->map, attr); 83 spin_lock_init(&m->lock); 84 85 return &m->map; 86 } 87 88 static u64 xsk_map_mem_usage(const struct bpf_map *map) 89 { 90 struct xsk_map *m = container_of(map, struct xsk_map, map); 91 92 return struct_size(m, xsk_map, map->max_entries) + 93 (u64)atomic_read(&m->count) * sizeof(struct xsk_map_node); 94 } 95 96 static void xsk_map_free(struct bpf_map *map) 97 { 98 struct xsk_map *m = container_of(map, struct xsk_map, map); 99 100 synchronize_net(); 101 bpf_map_area_free(m); 102 } 103 104 static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key) 105 { 106 struct xsk_map *m = container_of(map, struct xsk_map, map); 107 u32 index = key ? *(u32 *)key : U32_MAX; 108 u32 *next = next_key; 109 110 if (index >= m->map.max_entries) { 111 *next = 0; 112 return 0; 113 } 114 115 if (index == m->map.max_entries - 1) 116 return -ENOENT; 117 *next = index + 1; 118 return 0; 119 } 120 121 static int xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf) 122 { 123 const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2; 124 struct bpf_insn *insn = insn_buf; 125 126 *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0); 127 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5); 128 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *))); 129 *insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map)); 130 *insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp); 131 *insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0); 132 *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1); 133 *insn++ = BPF_MOV64_IMM(ret, 0); 134 return insn - insn_buf; 135 } 136 137 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or 138 * by local_bh_disable() (from XDP calls inside NAPI). The 139 * rcu_read_lock_bh_held() below makes lockdep accept both. 140 */ 141 static void *__xsk_map_lookup_elem(struct bpf_map *map, u32 key) 142 { 143 struct xsk_map *m = container_of(map, struct xsk_map, map); 144 145 if (key >= map->max_entries) 146 return NULL; 147 148 return rcu_dereference_check(m->xsk_map[key], rcu_read_lock_bh_held()); 149 } 150 151 static void *xsk_map_lookup_elem(struct bpf_map *map, void *key) 152 { 153 return __xsk_map_lookup_elem(map, *(u32 *)key); 154 } 155 156 static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key) 157 { 158 return ERR_PTR(-EOPNOTSUPP); 159 } 160 161 static long xsk_map_update_elem(struct bpf_map *map, void *key, void *value, 162 u64 map_flags) 163 { 164 struct xsk_map *m = container_of(map, struct xsk_map, map); 165 struct xdp_sock __rcu **map_entry; 166 struct xdp_sock *xs, *old_xs; 167 u32 i = *(u32 *)key, fd = *(u32 *)value; 168 struct xsk_map_node *node; 169 struct socket *sock; 170 int err; 171 172 if (unlikely(map_flags > BPF_EXIST)) 173 return -EINVAL; 174 if (unlikely(i >= m->map.max_entries)) 175 return -E2BIG; 176 177 sock = sockfd_lookup(fd, &err); 178 if (!sock) 179 return err; 180 181 if (sock->sk->sk_family != PF_XDP) { 182 sockfd_put(sock); 183 return -EOPNOTSUPP; 184 } 185 186 xs = (struct xdp_sock *)sock->sk; 187 188 map_entry = &m->xsk_map[i]; 189 node = xsk_map_node_alloc(m, map_entry); 190 if (IS_ERR(node)) { 191 sockfd_put(sock); 192 return PTR_ERR(node); 193 } 194 195 spin_lock_bh(&m->lock); 196 old_xs = rcu_dereference_protected(*map_entry, lockdep_is_held(&m->lock)); 197 if (old_xs == xs) { 198 err = 0; 199 goto out; 200 } else if (old_xs && map_flags == BPF_NOEXIST) { 201 err = -EEXIST; 202 goto out; 203 } else if (!old_xs && map_flags == BPF_EXIST) { 204 err = -ENOENT; 205 goto out; 206 } 207 xsk_map_sock_add(xs, node); 208 rcu_assign_pointer(*map_entry, xs); 209 if (old_xs) 210 xsk_map_sock_delete(old_xs, map_entry); 211 spin_unlock_bh(&m->lock); 212 sockfd_put(sock); 213 return 0; 214 215 out: 216 spin_unlock_bh(&m->lock); 217 sockfd_put(sock); 218 xsk_map_node_free(node); 219 return err; 220 } 221 222 static long xsk_map_delete_elem(struct bpf_map *map, void *key) 223 { 224 struct xsk_map *m = container_of(map, struct xsk_map, map); 225 struct xdp_sock __rcu **map_entry; 226 struct xdp_sock *old_xs; 227 u32 k = *(u32 *)key; 228 229 if (k >= map->max_entries) 230 return -EINVAL; 231 232 spin_lock_bh(&m->lock); 233 map_entry = &m->xsk_map[k]; 234 old_xs = unrcu_pointer(xchg(map_entry, NULL)); 235 if (old_xs) 236 xsk_map_sock_delete(old_xs, map_entry); 237 spin_unlock_bh(&m->lock); 238 239 return 0; 240 } 241 242 static long xsk_map_redirect(struct bpf_map *map, u64 index, u64 flags) 243 { 244 return __bpf_xdp_redirect_map(map, index, flags, 0, 245 __xsk_map_lookup_elem); 246 } 247 248 void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs, 249 struct xdp_sock __rcu **map_entry) 250 { 251 spin_lock_bh(&map->lock); 252 if (rcu_access_pointer(*map_entry) == xs) { 253 rcu_assign_pointer(*map_entry, NULL); 254 xsk_map_sock_delete(xs, map_entry); 255 } 256 spin_unlock_bh(&map->lock); 257 } 258 259 static bool xsk_map_meta_equal(const struct bpf_map *meta0, 260 const struct bpf_map *meta1) 261 { 262 return meta0->max_entries == meta1->max_entries && 263 bpf_map_meta_equal(meta0, meta1); 264 } 265 266 BTF_ID_LIST_SINGLE(xsk_map_btf_ids, struct, xsk_map) 267 const struct bpf_map_ops xsk_map_ops = { 268 .map_meta_equal = xsk_map_meta_equal, 269 .map_alloc = xsk_map_alloc, 270 .map_free = xsk_map_free, 271 .map_get_next_key = xsk_map_get_next_key, 272 .map_lookup_elem = xsk_map_lookup_elem, 273 .map_gen_lookup = xsk_map_gen_lookup, 274 .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only, 275 .map_update_elem = xsk_map_update_elem, 276 .map_delete_elem = xsk_map_delete_elem, 277 .map_check_btf = map_check_no_btf, 278 .map_mem_usage = xsk_map_mem_usage, 279 .map_btf_id = &xsk_map_btf_ids[0], 280 .map_redirect = xsk_map_redirect, 281 }; 282