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/capability.h> 8 #include <net/xdp_sock.h> 9 #include <linux/slab.h> 10 #include <linux/sched.h> 11 12 #include "xsk.h" 13 14 int xsk_map_inc(struct xsk_map *map) 15 { 16 bpf_map_inc(&map->map); 17 return 0; 18 } 19 20 void xsk_map_put(struct xsk_map *map) 21 { 22 bpf_map_put(&map->map); 23 } 24 25 static struct xsk_map_node *xsk_map_node_alloc(struct xsk_map *map, 26 struct xdp_sock **map_entry) 27 { 28 struct xsk_map_node *node; 29 int err; 30 31 node = kzalloc(sizeof(*node), GFP_ATOMIC | __GFP_NOWARN); 32 if (!node) 33 return ERR_PTR(-ENOMEM); 34 35 err = xsk_map_inc(map); 36 if (err) { 37 kfree(node); 38 return ERR_PTR(err); 39 } 40 41 node->map = map; 42 node->map_entry = map_entry; 43 return node; 44 } 45 46 static void xsk_map_node_free(struct xsk_map_node *node) 47 { 48 xsk_map_put(node->map); 49 kfree(node); 50 } 51 52 static void xsk_map_sock_add(struct xdp_sock *xs, struct xsk_map_node *node) 53 { 54 spin_lock_bh(&xs->map_list_lock); 55 list_add_tail(&node->node, &xs->map_list); 56 spin_unlock_bh(&xs->map_list_lock); 57 } 58 59 static void xsk_map_sock_delete(struct xdp_sock *xs, 60 struct xdp_sock **map_entry) 61 { 62 struct xsk_map_node *n, *tmp; 63 64 spin_lock_bh(&xs->map_list_lock); 65 list_for_each_entry_safe(n, tmp, &xs->map_list, node) { 66 if (map_entry == n->map_entry) { 67 list_del(&n->node); 68 xsk_map_node_free(n); 69 } 70 } 71 spin_unlock_bh(&xs->map_list_lock); 72 } 73 74 static struct bpf_map *xsk_map_alloc(union bpf_attr *attr) 75 { 76 struct bpf_map_memory mem; 77 int err, numa_node; 78 struct xsk_map *m; 79 u64 size; 80 81 if (!capable(CAP_NET_ADMIN)) 82 return ERR_PTR(-EPERM); 83 84 if (attr->max_entries == 0 || attr->key_size != 4 || 85 attr->value_size != 4 || 86 attr->map_flags & ~(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)) 87 return ERR_PTR(-EINVAL); 88 89 numa_node = bpf_map_attr_numa_node(attr); 90 size = struct_size(m, xsk_map, attr->max_entries); 91 92 err = bpf_map_charge_init(&mem, size); 93 if (err < 0) 94 return ERR_PTR(err); 95 96 m = bpf_map_area_alloc(size, numa_node); 97 if (!m) { 98 bpf_map_charge_finish(&mem); 99 return ERR_PTR(-ENOMEM); 100 } 101 102 bpf_map_init_from_attr(&m->map, attr); 103 bpf_map_charge_move(&m->map.memory, &mem); 104 spin_lock_init(&m->lock); 105 106 return &m->map; 107 } 108 109 static void xsk_map_free(struct bpf_map *map) 110 { 111 struct xsk_map *m = container_of(map, struct xsk_map, map); 112 113 bpf_clear_redirect_map(map); 114 synchronize_net(); 115 bpf_map_area_free(m); 116 } 117 118 static int xsk_map_get_next_key(struct bpf_map *map, void *key, void *next_key) 119 { 120 struct xsk_map *m = container_of(map, struct xsk_map, map); 121 u32 index = key ? *(u32 *)key : U32_MAX; 122 u32 *next = next_key; 123 124 if (index >= m->map.max_entries) { 125 *next = 0; 126 return 0; 127 } 128 129 if (index == m->map.max_entries - 1) 130 return -ENOENT; 131 *next = index + 1; 132 return 0; 133 } 134 135 static u32 xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf) 136 { 137 const int ret = BPF_REG_0, mp = BPF_REG_1, index = BPF_REG_2; 138 struct bpf_insn *insn = insn_buf; 139 140 *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0); 141 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5); 142 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *))); 143 *insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map)); 144 *insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp); 145 *insn++ = BPF_LDX_MEM(BPF_SIZEOF(struct xsk_sock *), ret, ret, 0); 146 *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1); 147 *insn++ = BPF_MOV64_IMM(ret, 0); 148 return insn - insn_buf; 149 } 150 151 static void *xsk_map_lookup_elem(struct bpf_map *map, void *key) 152 { 153 WARN_ON_ONCE(!rcu_read_lock_held()); 154 return __xsk_map_lookup_elem(map, *(u32 *)key); 155 } 156 157 static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key) 158 { 159 return ERR_PTR(-EOPNOTSUPP); 160 } 161 162 static int xsk_map_update_elem(struct bpf_map *map, void *key, void *value, 163 u64 map_flags) 164 { 165 struct xsk_map *m = container_of(map, struct xsk_map, map); 166 struct xdp_sock *xs, *old_xs, **map_entry; 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 if (!xsk_is_setup_for_bpf_map(xs)) { 189 sockfd_put(sock); 190 return -EOPNOTSUPP; 191 } 192 193 map_entry = &m->xsk_map[i]; 194 node = xsk_map_node_alloc(m, map_entry); 195 if (IS_ERR(node)) { 196 sockfd_put(sock); 197 return PTR_ERR(node); 198 } 199 200 spin_lock_bh(&m->lock); 201 old_xs = READ_ONCE(*map_entry); 202 if (old_xs == xs) { 203 err = 0; 204 goto out; 205 } else if (old_xs && map_flags == BPF_NOEXIST) { 206 err = -EEXIST; 207 goto out; 208 } else if (!old_xs && map_flags == BPF_EXIST) { 209 err = -ENOENT; 210 goto out; 211 } 212 xsk_map_sock_add(xs, node); 213 WRITE_ONCE(*map_entry, xs); 214 if (old_xs) 215 xsk_map_sock_delete(old_xs, map_entry); 216 spin_unlock_bh(&m->lock); 217 sockfd_put(sock); 218 return 0; 219 220 out: 221 spin_unlock_bh(&m->lock); 222 sockfd_put(sock); 223 xsk_map_node_free(node); 224 return err; 225 } 226 227 static int xsk_map_delete_elem(struct bpf_map *map, void *key) 228 { 229 struct xsk_map *m = container_of(map, struct xsk_map, map); 230 struct xdp_sock *old_xs, **map_entry; 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 = 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 void xsk_map_try_sock_delete(struct xsk_map *map, struct xdp_sock *xs, 247 struct xdp_sock **map_entry) 248 { 249 spin_lock_bh(&map->lock); 250 if (READ_ONCE(*map_entry) == xs) { 251 WRITE_ONCE(*map_entry, NULL); 252 xsk_map_sock_delete(xs, map_entry); 253 } 254 spin_unlock_bh(&map->lock); 255 } 256 257 static int xsk_map_btf_id; 258 const struct bpf_map_ops xsk_map_ops = { 259 .map_alloc = xsk_map_alloc, 260 .map_free = xsk_map_free, 261 .map_get_next_key = xsk_map_get_next_key, 262 .map_lookup_elem = xsk_map_lookup_elem, 263 .map_gen_lookup = xsk_map_gen_lookup, 264 .map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only, 265 .map_update_elem = xsk_map_update_elem, 266 .map_delete_elem = xsk_map_delete_elem, 267 .map_check_btf = map_check_no_btf, 268 .map_btf_name = "xsk_map", 269 .map_btf_id = &xsk_map_btf_id, 270 }; 271