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 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 bpf_map_put(&node->map->map); 36 kfree(node); 37 } 38 39 static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node) 40 { 41 spin_lock_bh(&xs->map_list_lock); 42 list_add_tail(&node->node, &xs->map_list); 43 spin_unlock_bh(&xs->map_list_lock); 44 } 45 46 static void xsk_map_sock_delete(struct xdp_sock *xs, 47 struct xdp_sock __rcu **map_entry) 48 { 49 struct xsk_map_node *n, *tmp; 50 51 spin_lock_bh(&xs->map_list_lock); 52 list_for_each_entry_safe(n, tmp, &xs->map_list, node) { 53 if (map_entry == n->map_entry) { 54 list_del(&n->node); 55 xsk_map_node_free(n); 56 } 57 } 58 spin_unlock_bh(&xs->map_list_lock); 59 } 60 61 static struct bpf_map *xsk_map_alloc(union bpf_attr *attr) 62 { 63 struct xsk_map *m; 64 int numa_node; 65 u64 size; 66 67 if (!capable(CAP_NET_ADMIN)) 68 return ERR_PTR(-EPERM); 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 void xsk_map_free(struct bpf_map *map) 89 { 90 struct xsk_map *m = container_of(map, struct xsk_map, map); 91 92 synchronize_net(); 93 bpf_map_area_free(m); 94 } 95 96 static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key) 97 { 98 struct xsk_map *m = container_of(map, struct xsk_map, map); 99 u32 index = key ? *(u32 *)key : U32_MAX; 100 u32 *next = next_key; 101 102 if (index >= m->map.max_entries) { 103 *next = 0; 104 return 0; 105 } 106 107 if (index == m->map.max_entries - 1) 108 return -ENOENT; 109 *next = index + 1; 110 return 0; 111 } 112 113 static int xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf) 114 { 115 const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2; 116 struct bpf_insn *insn = insn_buf; 117 118 *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0); 119 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5); 120 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *))); 121 *insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map)); 122 *insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp); 123 *insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0); 124 *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1); 125 *insn++ = BPF_MOV64_IMM(ret, 0); 126 return insn - insn_buf; 127 } 128 129 /* Elements are kept alive by RCU; either by rcu_read_lock() (from syscall) or 130 * by local_bh_disable() (from XDP calls inside NAPI). The 131 * rcu_read_lock_bh_held() below makes lockdep accept both. 132 */ 133 static void *__xsk_map_lookup_elem(struct bpf_map *map, u32 key) 134 { 135 struct xsk_map *m = container_of(map, struct xsk_map, map); 136 137 if (key >= map->max_entries) 138 return NULL; 139 140 return rcu_dereference_check(m->xsk_map[key], rcu_read_lock_bh_held()); 141 } 142 143 static void *xsk_map_lookup_elem(struct bpf_map *map, void *key) 144 { 145 return __xsk_map_lookup_elem(map, *(u32 *)key); 146 } 147 148 static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key) 149 { 150 return ERR_PTR(-EOPNOTSUPP); 151 } 152 153 static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value, 154 u64 map_flags) 155 { 156 struct xsk_map *m = container_of(map, struct xsk_map, map); 157 struct xdp_sock __rcu **map_entry; 158 struct xdp_sock *xs, *old_xs; 159 u32 i = *(u32 *)key, fd = *(u32 *)value; 160 struct xsk_map_node *node; 161 struct socket *sock; 162 int err; 163 164 if (unlikely(map_flags > BPF_EXIST)) 165 return -EINVAL; 166 if (unlikely(i >= m->map.max_entries)) 167 return -E2BIG; 168 169 sock = sockfd_lookup(fd, &err); 170 if (!sock) 171 return err; 172 173 if (sock->sk->sk_family != PF_XDP) { 174 sockfd_put(sock); 175 return -EOPNOTSUPP; 176 } 177 178 xs = (struct xdp_sock *)sock->sk; 179 180 map_entry = &m->xsk_map[i]; 181 node = xsk_map_node_alloc(m, map_entry); 182 if (IS_ERR(node)) { 183 sockfd_put(sock); 184 return PTR_ERR(node); 185 } 186 187 spin_lock_bh(&m->lock); 188 old_xs = rcu_dereference_protected(*map_entry, lockdep_is_held(&m->lock)); 189 if (old_xs == xs) { 190 err = 0; 191 goto out; 192 } else if (old_xs && map_flags == BPF_NOEXIST) { 193 err = -EEXIST; 194 goto out; 195 } else if (!old_xs && map_flags == BPF_EXIST) { 196 err = -ENOENT; 197 goto out; 198 } 199 xsk_map_sock_add(xs, node); 200 rcu_assign_pointer(*map_entry, xs); 201 if (old_xs) 202 xsk_map_sock_delete(old_xs, map_entry); 203 spin_unlock_bh(&m->lock); 204 sockfd_put(sock); 205 return 0; 206 207 out: 208 spin_unlock_bh(&m->lock); 209 sockfd_put(sock); 210 xsk_map_node_free(node); 211 return err; 212 } 213 214 static int xsk_map_delete_elem(struct bpf_map *map, void *key) 215 { 216 struct xsk_map *m = container_of(map, struct xsk_map, map); 217 struct xdp_sock __rcu **map_entry; 218 struct xdp_sock *old_xs; 219 int k = *(u32 *)key; 220 221 if (k >= map->max_entries) 222 return -EINVAL; 223 224 spin_lock_bh(&m->lock); 225 map_entry = &m->xsk_map[k]; 226 old_xs = unrcu_pointer(xchg(map_entry, NULL)); 227 if (old_xs) 228 xsk_map_sock_delete(old_xs, map_entry); 229 spin_unlock_bh(&m->lock); 230 231 return 0; 232 } 233 234 static int xsk_map_redirect(struct bpf_map *map, u32 ifindex, u64 flags) 235 { 236 return __bpf_xdp_redirect_map(map, ifindex, flags, 0, 237 __xsk_map_lookup_elem); 238 } 239 240 void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs, 241 struct xdp_sock __rcu **map_entry) 242 { 243 spin_lock_bh(&map->lock); 244 if (rcu_access_pointer(*map_entry) == xs) { 245 rcu_assign_pointer(*map_entry, NULL); 246 xsk_map_sock_delete(xs, map_entry); 247 } 248 spin_unlock_bh(&map->lock); 249 } 250 251 static bool xsk_map_meta_equal(const struct bpf_map *meta0, 252 const struct bpf_map *meta1) 253 { 254 return meta0->max_entries == meta1->max_entries && 255 bpf_map_meta_equal(meta0, meta1); 256 } 257 258 BTF_ID_LIST_SINGLE(xsk_map_btf_ids, struct, xsk_map) 259 const struct bpf_map_ops xsk_map_ops = { 260 .map_meta_equal = xsk_map_meta_equal, 261 .map_alloc = xsk_map_alloc, 262 .map_free = xsk_map_free, 263 .map_get_next_key = xsk_map_get_next_key, 264 .map_lookup_elem = xsk_map_lookup_elem, 265 .map_gen_lookup = xsk_map_gen_lookup, 266 .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only, 267 .map_update_elem = xsk_map_update_elem, 268 .map_delete_elem = xsk_map_delete_elem, 269 .map_check_btf = map_check_no_btf, 270 .map_btf_id = &xsk_map_btf_ids[0], 271 .map_redirect = xsk_map_redirect, 272 }; 273