drivers/net/wireguard/socket.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2015-2019 Jason A. Donenfeld <[email protected]>. All Rights Reserved.
   4  */
   5
   6 #include "device.h"
   7 #include "peer.h"
   8 #include "socket.h"
   9 #include "queueing.h"
  10 #include "messages.h"
  11
  12 #include <linux/ctype.h>
  13 #include <linux/net.h>
  14 #include <linux/if_vlan.h>
  15 #include <linux/if_ether.h>
  16 #include <linux/inetdevice.h>
  17 #include <net/udp_tunnel.h>
  18 #include <net/ipv6.h>
  19
  20 static int send4(struct wg_device *wg, struct sk_buff *skb,
  21                  struct endpoint *endpoint, u8 ds, struct dst_cache *cache)
  22 {
  23         struct flowi4 fl = {
  24                 .saddr = endpoint->src4.s_addr,
  25                 .daddr = endpoint->addr4.sin_addr.s_addr,
  26                 .fl4_dport = endpoint->addr4.sin_port,
  27                 .flowi4_mark = wg->fwmark,
  28                 .flowi4_proto = IPPROTO_UDP
  29         };
  30         struct rtable *rt = NULL;
  31         struct sock *sock;
  32         int ret = 0;
  33
  34         skb_mark_not_on_list(skb);
  35         skb->dev = wg->dev;
  36         skb->mark = wg->fwmark;
  37
  38         rcu_read_lock_bh();
  39         sock = rcu_dereference_bh(wg->sock4);
  40
  41         if (unlikely(!sock)) {
  42                 ret = -ENONET;
  43                 goto err;
  44         }
  45
  46         fl.fl4_sport = inet_sk(sock)->inet_sport;
  47
  48         if (cache)
  49                 rt = dst_cache_get_ip4(cache, &fl.saddr);
  50
  51         if (!rt) {
  52                 security_sk_classify_flow(sock, flowi4_to_flowi(&fl));
  53                 if (unlikely(!inet_confirm_addr(sock_net(sock), NULL, 0,
  54                                                 fl.saddr, RT_SCOPE_HOST))) {
  55                         endpoint->src4.s_addr = 0;
  56                         *(__force __be32 *)&endpoint->src_if4 = 0;
  57                         fl.saddr = 0;
  58                         if (cache)
  59                                 dst_cache_reset(cache);
  60                 }
  61                 rt = ip_route_output_flow(sock_net(sock), &fl, sock);
  62                 if (unlikely(endpoint->src_if4 && ((IS_ERR(rt) &&
  63                              PTR_ERR(rt) == -EINVAL) || (!IS_ERR(rt) &&
  64                              rt->dst.dev->ifindex != endpoint->src_if4)))) {
  65                         endpoint->src4.s_addr = 0;
  66                         *(__force __be32 *)&endpoint->src_if4 = 0;
  67                         fl.saddr = 0;
  68                         if (cache)
  69                                 dst_cache_reset(cache);
  70                         if (!IS_ERR(rt))
  71                                 ip_rt_put(rt);
  72                         rt = ip_route_output_flow(sock_net(sock), &fl, sock);
  73                 }
  74                 if (unlikely(IS_ERR(rt))) {
  75                         ret = PTR_ERR(rt);
  76                         net_dbg_ratelimited("%s: No route to %pISpfsc, error %d\n",
  77                                             wg->dev->name, &endpoint->addr, ret);
  78                         goto err;
  79                 } else if (unlikely(rt->dst.dev == skb->dev)) {
  80                         ip_rt_put(rt);
  81                         ret = -ELOOP;
  82                         net_dbg_ratelimited("%s: Avoiding routing loop to %pISpfsc\n",
  83                                             wg->dev->name, &endpoint->addr);
  84                         goto err;
  85                 }
  86                 if (cache)
  87                         dst_cache_set_ip4(cache, &rt->dst, fl.saddr);
  88         }
  89
  90         skb->ignore_df = 1;
  91         udp_tunnel_xmit_skb(rt, sock, skb, fl.saddr, fl.daddr, ds,
  92                             ip4_dst_hoplimit(&rt->dst), 0, fl.fl4_sport,
  93                             fl.fl4_dport, false, false);
  94         goto out;
  95
  96 err:
  97         kfree_skb(skb);
  98 out:
  99         rcu_read_unlock_bh();
 100         return ret;
 101 }
 102
 103 static int send6(struct wg_device *wg, struct sk_buff *skb,
 104                  struct endpoint *endpoint, u8 ds, struct dst_cache *cache)
 105 {
 106 #if IS_ENABLED(CONFIG_IPV6)
 107         struct flowi6 fl = {
 108                 .saddr = endpoint->src6,
 109                 .daddr = endpoint->addr6.sin6_addr,
 110                 .fl6_dport = endpoint->addr6.sin6_port,
 111                 .flowi6_mark = wg->fwmark,
 112                 .flowi6_oif = endpoint->addr6.sin6_scope_id,
 113                 .flowi6_proto = IPPROTO_UDP
 114                 /* TODO: addr->sin6_flowinfo */
 115         };
 116         struct dst_entry *dst = NULL;
 117         struct sock *sock;
 118         int ret = 0;
 119
 120         skb_mark_not_on_list(skb);
 121         skb->dev = wg->dev;
 122         skb->mark = wg->fwmark;
 123
 124         rcu_read_lock_bh();
 125         sock = rcu_dereference_bh(wg->sock6);
 126
 127         if (unlikely(!sock)) {
 128                 ret = -ENONET;
 129                 goto err;
 130         }
 131
 132         fl.fl6_sport = inet_sk(sock)->inet_sport;
 133
 134         if (cache)
 135                 dst = dst_cache_get_ip6(cache, &fl.saddr);
 136
 137         if (!dst) {
 138                 security_sk_classify_flow(sock, flowi6_to_flowi(&fl));
 139                 if (unlikely(!ipv6_addr_any(&fl.saddr) &&
 140                              !ipv6_chk_addr(sock_net(sock), &fl.saddr, NULL, 0))) {
 141                         endpoint->src6 = fl.saddr = in6addr_any;
 142                         if (cache)
 143                                 dst_cache_reset(cache);
 144                 }
 145                 dst = ipv6_stub->ipv6_dst_lookup_flow(sock_net(sock), sock, &fl,
 146                                                       NULL);
 147                 if (unlikely(IS_ERR(dst))) {
 148                         ret = PTR_ERR(dst);
 149                         net_dbg_ratelimited("%s: No route to %pISpfsc, error %d\n",
 150                                             wg->dev->name, &endpoint->addr, ret);
 151                         goto err;
 152                 } else if (unlikely(dst->dev == skb->dev)) {
 153                         dst_release(dst);
 154                         ret = -ELOOP;
 155                         net_dbg_ratelimited("%s: Avoiding routing loop to %pISpfsc\n",
 156                                             wg->dev->name, &endpoint->addr);
 157                         goto err;
 158                 }
 159                 if (cache)
 160                         dst_cache_set_ip6(cache, dst, &fl.saddr);
 161         }
 162
 163         skb->ignore_df = 1;
 164         udp_tunnel6_xmit_skb(dst, sock, skb, skb->dev, &fl.saddr, &fl.daddr, ds,
 165                              ip6_dst_hoplimit(dst), 0, fl.fl6_sport,
 166                              fl.fl6_dport, false);
 167         goto out;
 168
 169 err:
 170         kfree_skb(skb);
 171 out:
 172         rcu_read_unlock_bh();
 173         return ret;
 174 #else
 175         return -EAFNOSUPPORT;
 176 #endif
 177 }
 178
 179 int wg_socket_send_skb_to_peer(struct wg_peer *peer, struct sk_buff *skb, u8 ds)
 180 {
 181         size_t skb_len = skb->len;
 182         int ret = -EAFNOSUPPORT;
 183
 184         read_lock_bh(&peer->endpoint_lock);
 185         if (peer->endpoint.addr.sa_family == AF_INET)
 186                 ret = send4(peer->device, skb, &peer->endpoint, ds,
 187                             &peer->endpoint_cache);
 188         else if (peer->endpoint.addr.sa_family == AF_INET6)
 189                 ret = send6(peer->device, skb, &peer->endpoint, ds,
 190                             &peer->endpoint_cache);
 191         else
 192                 dev_kfree_skb(skb);
 193         if (likely(!ret))
 194                 peer->tx_bytes += skb_len;
 195         read_unlock_bh(&peer->endpoint_lock);
 196
 197         return ret;
 198 }
 199
 200 int wg_socket_send_buffer_to_peer(struct wg_peer *peer, void *buffer,
 201                                   size_t len, u8 ds)
 202 {
 203         struct sk_buff *skb = alloc_skb(len + SKB_HEADER_LEN, GFP_ATOMIC);
 204
 205         if (unlikely(!skb))
 206                 return -ENOMEM;
 207
 208         skb_reserve(skb, SKB_HEADER_LEN);
 209         skb_set_inner_network_header(skb, 0);
 210         skb_put_data(skb, buffer, len);
 211         return wg_socket_send_skb_to_peer(peer, skb, ds);
 212 }
 213
 214 int wg_socket_send_buffer_as_reply_to_skb(struct wg_device *wg,
 215                                           struct sk_buff *in_skb, void *buffer,
 216                                           size_t len)
 217 {
 218         int ret = 0;
 219         struct sk_buff *skb;
 220         struct endpoint endpoint;
 221
 222         if (unlikely(!in_skb))
 223                 return -EINVAL;
 224         ret = wg_socket_endpoint_from_skb(&endpoint, in_skb);
 225         if (unlikely(ret < 0))
 226                 return ret;
 227
 228         skb = alloc_skb(len + SKB_HEADER_LEN, GFP_ATOMIC);
 229         if (unlikely(!skb))
 230                 return -ENOMEM;
 231         skb_reserve(skb, SKB_HEADER_LEN);
 232         skb_set_inner_network_header(skb, 0);
 233         skb_put_data(skb, buffer, len);
 234
 235         if (endpoint.addr.sa_family == AF_INET)
 236                 ret = send4(wg, skb, &endpoint, 0, NULL);
 237         else if (endpoint.addr.sa_family == AF_INET6)
 238                 ret = send6(wg, skb, &endpoint, 0, NULL);
 239         /* No other possibilities if the endpoint is valid, which it is,
 240          * as we checked above.
 241          */
 242
 243         return ret;
 244 }
 245
 246 int wg_socket_endpoint_from_skb(struct endpoint *endpoint,
 247                                 const struct sk_buff *skb)
 248 {
 249         memset(endpoint, 0, sizeof(*endpoint));
 250         if (skb->protocol == htons(ETH_P_IP)) {
 251                 endpoint->addr4.sin_family = AF_INET;
 252                 endpoint->addr4.sin_port = udp_hdr(skb)->source;
 253                 endpoint->addr4.sin_addr.s_addr = ip_hdr(skb)->saddr;
 254                 endpoint->src4.s_addr = ip_hdr(skb)->daddr;
 255                 endpoint->src_if4 = skb->skb_iif;
 256         } else if (skb->protocol == htons(ETH_P_IPV6)) {
 257                 endpoint->addr6.sin6_family = AF_INET6;
 258                 endpoint->addr6.sin6_port = udp_hdr(skb)->source;
 259                 endpoint->addr6.sin6_addr = ipv6_hdr(skb)->saddr;
 260                 endpoint->addr6.sin6_scope_id = ipv6_iface_scope_id(
 261                         &ipv6_hdr(skb)->saddr, skb->skb_iif);
 262                 endpoint->src6 = ipv6_hdr(skb)->daddr;
 263         } else {
 264                 return -EINVAL;
 265         }
 266         return 0;
 267 }
 268
 269 static bool endpoint_eq(const struct endpoint *a, const struct endpoint *b)
 270 {
 271         return (a->addr.sa_family == AF_INET && b->addr.sa_family == AF_INET &&
 272                 a->addr4.sin_port == b->addr4.sin_port &&
 273                 a->addr4.sin_addr.s_addr == b->addr4.sin_addr.s_addr &&
 274                 a->src4.s_addr == b->src4.s_addr && a->src_if4 == b->src_if4) ||
 275                (a->addr.sa_family == AF_INET6 &&
 276                 b->addr.sa_family == AF_INET6 &&
 277                 a->addr6.sin6_port == b->addr6.sin6_port &&
 278                 ipv6_addr_equal(&a->addr6.sin6_addr, &b->addr6.sin6_addr) &&
 279                 a->addr6.sin6_scope_id == b->addr6.sin6_scope_id &&
 280                 ipv6_addr_equal(&a->src6, &b->src6)) ||
 281                unlikely(!a->addr.sa_family && !b->addr.sa_family);
 282 }
 283
 284 void wg_socket_set_peer_endpoint(struct wg_peer *peer,
 285                                  const struct endpoint *endpoint)
 286 {
 287         /* First we check unlocked, in order to optimize, since it's pretty rare
 288          * that an endpoint will change. If we happen to be mid-write, and two
 289          * CPUs wind up writing the same thing or something slightly different,
 290          * it doesn't really matter much either.
 291          */
 292         if (endpoint_eq(endpoint, &peer->endpoint))
 293                 return;
 294         write_lock_bh(&peer->endpoint_lock);
 295         if (endpoint->addr.sa_family == AF_INET) {
 296                 peer->endpoint.addr4 = endpoint->addr4;
 297                 peer->endpoint.src4 = endpoint->src4;
 298                 peer->endpoint.src_if4 = endpoint->src_if4;
 299         } else if (endpoint->addr.sa_family == AF_INET6) {
 300                 peer->endpoint.addr6 = endpoint->addr6;
 301                 peer->endpoint.src6 = endpoint->src6;
 302         } else {
 303                 goto out;
 304         }
 305         dst_cache_reset(&peer->endpoint_cache);
 306 out:
 307         write_unlock_bh(&peer->endpoint_lock);
 308 }
 309
 310 void wg_socket_set_peer_endpoint_from_skb(struct wg_peer *peer,
 311                                           const struct sk_buff *skb)
 312 {
 313         struct endpoint endpoint;
 314
 315         if (!wg_socket_endpoint_from_skb(&endpoint, skb))
 316                 wg_socket_set_peer_endpoint(peer, &endpoint);
 317 }
 318
 319 void wg_socket_clear_peer_endpoint_src(struct wg_peer *peer)
 320 {
 321         write_lock_bh(&peer->endpoint_lock);
 322         memset(&peer->endpoint.src6, 0, sizeof(peer->endpoint.src6));
 323         dst_cache_reset(&peer->endpoint_cache);
 324         write_unlock_bh(&peer->endpoint_lock);
 325 }
 326
 327 static int wg_receive(struct sock *sk, struct sk_buff *skb)
 328 {
 329         struct wg_device *wg;
 330
 331         if (unlikely(!sk))
 332                 goto err;
 333         wg = sk->sk_user_data;
 334         if (unlikely(!wg))
 335                 goto err;
 336         skb_mark_not_on_list(skb);
 337         wg_packet_receive(wg, skb);
 338         return 0;
 339
 340 err:
 341         kfree_skb(skb);
 342         return 0;
 343 }
 344
 345 static void sock_free(struct sock *sock)
 346 {
 347         if (unlikely(!sock))
 348                 return;
 349         sk_clear_memalloc(sock);
 350         udp_tunnel_sock_release(sock->sk_socket);
 351 }
 352
 353 static void set_sock_opts(struct socket *sock)
 354 {
 355         sock->sk->sk_allocation = GFP_ATOMIC;
 356         sock->sk->sk_sndbuf = INT_MAX;
 357         sk_set_memalloc(sock->sk);
 358 }
 359
 360 int wg_socket_init(struct wg_device *wg, u16 port)
 361 {
 362         int ret;
 363         struct udp_tunnel_sock_cfg cfg = {
 364                 .sk_user_data = wg,
 365                 .encap_type = 1,
 366                 .encap_rcv = wg_receive
 367         };
 368         struct socket *new4 = NULL, *new6 = NULL;
 369         struct udp_port_cfg port4 = {
 370                 .family = AF_INET,
 371                 .local_ip.s_addr = htonl(INADDR_ANY),
 372                 .local_udp_port = htons(port),
 373                 .use_udp_checksums = true
 374         };
 375 #if IS_ENABLED(CONFIG_IPV6)
 376         int retries = 0;
 377         struct udp_port_cfg port6 = {
 378                 .family = AF_INET6,
 379                 .local_ip6 = IN6ADDR_ANY_INIT,
 380                 .use_udp6_tx_checksums = true,
 381                 .use_udp6_rx_checksums = true,
 382                 .ipv6_v6only = true
 383         };
 384 #endif
 385
 386 #if IS_ENABLED(CONFIG_IPV6)
 387 retry:
 388 #endif
 389
 390         ret = udp_sock_create(wg->creating_net, &port4, &new4);
 391         if (ret < 0) {
 392                 pr_err("%s: Could not create IPv4 socket\n", wg->dev->name);
 393                 return ret;
 394         }
 395         set_sock_opts(new4);
 396         setup_udp_tunnel_sock(wg->creating_net, new4, &cfg);
 397
 398 #if IS_ENABLED(CONFIG_IPV6)
 399         if (ipv6_mod_enabled()) {
 400                 port6.local_udp_port = inet_sk(new4->sk)->inet_sport;
 401                 ret = udp_sock_create(wg->creating_net, &port6, &new6);
 402                 if (ret < 0) {
 403                         udp_tunnel_sock_release(new4);
 404                         if (ret == -EADDRINUSE && !port && retries++ < 100)
 405                                 goto retry;
 406                         pr_err("%s: Could not create IPv6 socket\n",
 407                                wg->dev->name);
 408                         return ret;
 409                 }
 410                 set_sock_opts(new6);
 411                 setup_udp_tunnel_sock(wg->creating_net, new6, &cfg);
 412         }
 413 #endif
 414
 415         wg_socket_reinit(wg, new4->sk, new6 ? new6->sk : NULL);
 416         return 0;
 417 }
 418
 419 void wg_socket_reinit(struct wg_device *wg, struct sock *new4,
 420                       struct sock *new6)
 421 {
 422         struct sock *old4, *old6;
 423
 424         mutex_lock(&wg->socket_update_lock);
 425         old4 = rcu_dereference_protected(wg->sock4,
 426                                 lockdep_is_held(&wg->socket_update_lock));
 427         old6 = rcu_dereference_protected(wg->sock6,
 428                                 lockdep_is_held(&wg->socket_update_lock));
 429         rcu_assign_pointer(wg->sock4, new4);
 430         rcu_assign_pointer(wg->sock6, new6);
 431         if (new4)
 432                 wg->incoming_port = ntohs(inet_sk(new4)->inet_sport);
 433         mutex_unlock(&wg->socket_update_lock);
 434         synchronize_rcu();
 435         synchronize_net();
 436         sock_free(old4);
 437         sock_free(old6);
 438 }