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 <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> 13 14 #include "xsk.h" 15 16 static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map, 17 struct xdp_sock __rcu **map_entry) 18 { 19 struct xsk_map_node *node; 20 21 node = bpf_map_kzalloc(&map->map, sizeof(*node), 22 GFP_ATOMIC | __GFP_NOWARN); 23 if (!node) 24 return ERR_PTR(-ENOMEM); 25 26 bpf_map_inc(&map->map); 27 atomic_inc(&map->count); 28 29 node->map = map; 30 node->map_entry = map_entry; 31 return node; 32 } 33 34 static void xsk_map_node_free(struct xsk_map_node *node) 35 { 36 struct xsk_map *map = node->map; 37 38 bpf_map_put(&node->map->map); 39 kfree(node); 40 atomic_dec(&map->count); 41 } 42 43 static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node) 44 { 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); 48 } 49 50 static void xsk_map_sock_delete(struct xdp_sock *xs, 51 struct xdp_sock __rcu **map_entry) 52 { 53 struct xsk_map_node *n, *tmp; 54 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) { 58 list_del(&n->node); 59 xsk_map_node_free(n); 60 } 61 } 62 spin_unlock_bh(&xs->map_list_lock); 63 } 64 65 static struct bpf_map *xsk_map_alloc(union bpf_attr *attr) 66 { 67 struct xsk_map *m; 68 int numa_node; 69 u64 size; 70 71 if (!capable(CAP_NET_ADMIN)) 72 return ERR_PTR(-EPERM); 73 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); 78 79 numa_node = bpf_map_attr_numa_node(attr); 80 size = struct_size(m, xsk_map, attr->max_entries); 81 82 m = bpf_map_area_alloc(size, numa_node); 83 if (!m) 84 return ERR_PTR(-ENOMEM); 85 86 bpf_map_init_from_attr(&m->map, attr); 87 spin_lock_init(&m->lock); 88 89 return &m->map; 90 } 91 92 static u64 xsk_map_mem_usage(const struct bpf_map *map) 93 { 94 struct xsk_map *m = container_of(map, struct xsk_map, map); 95 96 return struct_size(m, xsk_map, map->max_entries) + 97 (u64)atomic_read(&m->count) * sizeof(struct xsk_map_node); 98 } 99 100 static void xsk_map_free(struct bpf_map *map) 101 { 102 struct xsk_map *m = container_of(map, struct xsk_map, map); 103 104 synchronize_net(); 105 bpf_map_area_free(m); 106 } 107 108 static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key) 109 { 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; 113 114 if (index >= m->map.max_entries) { 115 *next = 0; 116 return 0; 117 } 118 119 if (index == m->map.max_entries - 1) 120 return -ENOENT; 121 *next = index + 1; 122 return 0; 123 } 124 125 static int xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf) 126 { 127 const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2; 128 struct bpf_insn *insn = insn_buf; 129 130 *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; 139 } 140 141 /* 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. 144 */ 145 static void *__xsk_map_lookup_elem(struct bpf_map *map, u32 key) 146 { 147 struct xsk_map *m = container_of(map, struct xsk_map, map); 148 149 if (key >= map->max_entries) 150 return NULL; 151 152 return rcu_dereference_check(m->xsk_map[key], rcu_read_lock_bh_held()); 153 } 154 155 static void *xsk_map_lookup_elem(struct bpf_map *map, void *key) 156 { 157 return __xsk_map_lookup_elem(map, *(u32 *)key); 158 } 159 160 static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key) 161 { 162 return ERR_PTR(-EOPNOTSUPP); 163 } 164 165 static long xsk_map_update_elem(struct bpf_map *map, void *key, void *value, 166 u64 map_flags) 167 { 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; 173 struct socket *sock; 174 int err; 175 176 if (unlikely(map_flags > BPF_EXIST)) 177 return -EINVAL; 178 if (unlikely(i >= m->map.max_entries)) 179 return -E2BIG; 180 181 sock = sockfd_lookup(fd, &err); 182 if (!sock) 183 return err; 184 185 if (sock->sk->sk_family != PF_XDP) { 186 sockfd_put(sock); 187 return -EOPNOTSUPP; 188 } 189 190 xs = (struct xdp_sock *)sock->sk; 191 192 map_entry = &m->xsk_map[i]; 193 node = xsk_map_node_alloc(m, map_entry); 194 if (IS_ERR(node)) { 195 sockfd_put(sock); 196 return PTR_ERR(node); 197 } 198 199 spin_lock_bh(&m->lock); 200 old_xs = rcu_dereference_protected(*map_entry, lockdep_is_held(&m->lock)); 201 if (old_xs == xs) { 202 err = 0; 203 goto out; 204 } else if (old_xs && map_flags == BPF_NOEXIST) { 205 err = -EEXIST; 206 goto out; 207 } else if (!old_xs && map_flags == BPF_EXIST) { 208 err = -ENOENT; 209 goto out; 210 } 211 xsk_map_sock_add(xs, node); 212 rcu_assign_pointer(*map_entry, xs); 213 if (old_xs) 214 xsk_map_sock_delete(old_xs, map_entry); 215 spin_unlock_bh(&m->lock); 216 sockfd_put(sock); 217 return 0; 218 219 out: 220 spin_unlock_bh(&m->lock); 221 sockfd_put(sock); 222 xsk_map_node_free(node); 223 return err; 224 } 225 226 static long xsk_map_delete_elem(struct bpf_map *map, void *key) 227 { 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; 231 int k = *(u32 *)key; 232 233 if (k >= map->max_entries) 234 return -EINVAL; 235 236 spin_lock_bh(&m->lock); 237 map_entry = &m->xsk_map[k]; 238 old_xs = unrcu_pointer(xchg(map_entry, NULL)); 239 if (old_xs) 240 xsk_map_sock_delete(old_xs, map_entry); 241 spin_unlock_bh(&m->lock); 242 243 return 0; 244 } 245 246 static long xsk_map_redirect(struct bpf_map *map, u64 index, u64 flags) 247 { 248 return __bpf_xdp_redirect_map(map, index, flags, 0, 249 __xsk_map_lookup_elem); 250 } 251 252 void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs, 253 struct xdp_sock __rcu **map_entry) 254 { 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); 259 } 260 spin_unlock_bh(&map->lock); 261 } 262 263 static bool xsk_map_meta_equal(const struct bpf_map *meta0, 264 const struct bpf_map *meta1) 265 { 266 return meta0->max_entries == meta1->max_entries && 267 bpf_map_meta_equal(meta0, meta1); 268 } 269 270 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, 285 }; 286