1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. 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
send4(struct wg_device * wg,struct sk_buff * skb,struct endpoint * endpoint,u8 ds,struct dst_cache * cache)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_common(&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 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 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 (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 }
80 if (cache)
81 dst_cache_set_ip4(cache, &rt->dst, fl.saddr);
82 }
83
84 skb->ignore_df = 1;
85 udp_tunnel_xmit_skb(rt, sock, skb, fl.saddr, fl.daddr, ds,
86 ip4_dst_hoplimit(&rt->dst), 0, fl.fl4_sport,
87 fl.fl4_dport, false, false);
88 goto out;
89
90 err:
91 kfree_skb(skb);
92 out:
93 rcu_read_unlock_bh();
94 return ret;
95 }
96
send6(struct wg_device * wg,struct sk_buff * skb,struct endpoint * endpoint,u8 ds,struct dst_cache * cache)97 static int send6(struct wg_device *wg, struct sk_buff *skb,
98 struct endpoint *endpoint, u8 ds, struct dst_cache *cache)
99 {
100 #if IS_ENABLED(CONFIG_IPV6)
101 struct flowi6 fl = {
102 .saddr = endpoint->src6,
103 .daddr = endpoint->addr6.sin6_addr,
104 .fl6_dport = endpoint->addr6.sin6_port,
105 .flowi6_mark = wg->fwmark,
106 .flowi6_oif = endpoint->addr6.sin6_scope_id,
107 .flowi6_proto = IPPROTO_UDP
108 /* TODO: addr->sin6_flowinfo */
109 };
110 struct dst_entry *dst = NULL;
111 struct sock *sock;
112 int ret = 0;
113
114 skb_mark_not_on_list(skb);
115 skb->dev = wg->dev;
116 skb->mark = wg->fwmark;
117
118 rcu_read_lock_bh();
119 sock = rcu_dereference_bh(wg->sock6);
120
121 if (unlikely(!sock)) {
122 ret = -ENONET;
123 goto err;
124 }
125
126 fl.fl6_sport = inet_sk(sock)->inet_sport;
127
128 if (cache)
129 dst = dst_cache_get_ip6(cache, &fl.saddr);
130
131 if (!dst) {
132 security_sk_classify_flow(sock, flowi6_to_flowi_common(&fl));
133 if (unlikely(!ipv6_addr_any(&fl.saddr) &&
134 !ipv6_chk_addr(sock_net(sock), &fl.saddr, NULL, 0))) {
135 endpoint->src6 = fl.saddr = in6addr_any;
136 if (cache)
137 dst_cache_reset(cache);
138 }
139 dst = ipv6_stub->ipv6_dst_lookup_flow(sock_net(sock), sock, &fl,
140 NULL);
141 if (IS_ERR(dst)) {
142 ret = PTR_ERR(dst);
143 net_dbg_ratelimited("%s: No route to %pISpfsc, error %d\n",
144 wg->dev->name, &endpoint->addr, ret);
145 goto err;
146 }
147 if (cache)
148 dst_cache_set_ip6(cache, dst, &fl.saddr);
149 }
150
151 skb->ignore_df = 1;
152 udp_tunnel6_xmit_skb(dst, sock, skb, skb->dev, &fl.saddr, &fl.daddr, ds,
153 ip6_dst_hoplimit(dst), 0, fl.fl6_sport,
154 fl.fl6_dport, false);
155 goto out;
156
157 err:
158 kfree_skb(skb);
159 out:
160 rcu_read_unlock_bh();
161 return ret;
162 #else
163 kfree_skb(skb);
164 return -EAFNOSUPPORT;
165 #endif
166 }
167
wg_socket_send_skb_to_peer(struct wg_peer * peer,struct sk_buff * skb,u8 ds)168 int wg_socket_send_skb_to_peer(struct wg_peer *peer, struct sk_buff *skb, u8 ds)
169 {
170 size_t skb_len = skb->len;
171 int ret = -EAFNOSUPPORT;
172
173 read_lock_bh(&peer->endpoint_lock);
174 if (peer->endpoint.addr.sa_family == AF_INET)
175 ret = send4(peer->device, skb, &peer->endpoint, ds,
176 &peer->endpoint_cache);
177 else if (peer->endpoint.addr.sa_family == AF_INET6)
178 ret = send6(peer->device, skb, &peer->endpoint, ds,
179 &peer->endpoint_cache);
180 else
181 dev_kfree_skb(skb);
182 if (likely(!ret))
183 peer->tx_bytes += skb_len;
184 read_unlock_bh(&peer->endpoint_lock);
185
186 return ret;
187 }
188
wg_socket_send_buffer_to_peer(struct wg_peer * peer,void * buffer,size_t len,u8 ds)189 int wg_socket_send_buffer_to_peer(struct wg_peer *peer, void *buffer,
190 size_t len, u8 ds)
191 {
192 struct sk_buff *skb = alloc_skb(len + SKB_HEADER_LEN, GFP_ATOMIC);
193
194 if (unlikely(!skb))
195 return -ENOMEM;
196
197 skb_reserve(skb, SKB_HEADER_LEN);
198 skb_set_inner_network_header(skb, 0);
199 skb_put_data(skb, buffer, len);
200 return wg_socket_send_skb_to_peer(peer, skb, ds);
201 }
202
wg_socket_send_buffer_as_reply_to_skb(struct wg_device * wg,struct sk_buff * in_skb,void * buffer,size_t len)203 int wg_socket_send_buffer_as_reply_to_skb(struct wg_device *wg,
204 struct sk_buff *in_skb, void *buffer,
205 size_t len)
206 {
207 int ret = 0;
208 struct sk_buff *skb;
209 struct endpoint endpoint;
210
211 if (unlikely(!in_skb))
212 return -EINVAL;
213 ret = wg_socket_endpoint_from_skb(&endpoint, in_skb);
214 if (unlikely(ret < 0))
215 return ret;
216
217 skb = alloc_skb(len + SKB_HEADER_LEN, GFP_ATOMIC);
218 if (unlikely(!skb))
219 return -ENOMEM;
220 skb_reserve(skb, SKB_HEADER_LEN);
221 skb_set_inner_network_header(skb, 0);
222 skb_put_data(skb, buffer, len);
223
224 if (endpoint.addr.sa_family == AF_INET)
225 ret = send4(wg, skb, &endpoint, 0, NULL);
226 else if (endpoint.addr.sa_family == AF_INET6)
227 ret = send6(wg, skb, &endpoint, 0, NULL);
228 /* No other possibilities if the endpoint is valid, which it is,
229 * as we checked above.
230 */
231
232 return ret;
233 }
234
wg_socket_endpoint_from_skb(struct endpoint * endpoint,const struct sk_buff * skb)235 int wg_socket_endpoint_from_skb(struct endpoint *endpoint,
236 const struct sk_buff *skb)
237 {
238 memset(endpoint, 0, sizeof(*endpoint));
239 if (skb->protocol == htons(ETH_P_IP)) {
240 endpoint->addr4.sin_family = AF_INET;
241 endpoint->addr4.sin_port = udp_hdr(skb)->source;
242 endpoint->addr4.sin_addr.s_addr = ip_hdr(skb)->saddr;
243 endpoint->src4.s_addr = ip_hdr(skb)->daddr;
244 endpoint->src_if4 = skb->skb_iif;
245 } else if (IS_ENABLED(CONFIG_IPV6) && skb->protocol == htons(ETH_P_IPV6)) {
246 endpoint->addr6.sin6_family = AF_INET6;
247 endpoint->addr6.sin6_port = udp_hdr(skb)->source;
248 endpoint->addr6.sin6_addr = ipv6_hdr(skb)->saddr;
249 endpoint->addr6.sin6_scope_id = ipv6_iface_scope_id(
250 &ipv6_hdr(skb)->saddr, skb->skb_iif);
251 endpoint->src6 = ipv6_hdr(skb)->daddr;
252 } else {
253 return -EINVAL;
254 }
255 return 0;
256 }
257
endpoint_eq(const struct endpoint * a,const struct endpoint * b)258 static bool endpoint_eq(const struct endpoint *a, const struct endpoint *b)
259 {
260 return (a->addr.sa_family == AF_INET && b->addr.sa_family == AF_INET &&
261 a->addr4.sin_port == b->addr4.sin_port &&
262 a->addr4.sin_addr.s_addr == b->addr4.sin_addr.s_addr &&
263 a->src4.s_addr == b->src4.s_addr && a->src_if4 == b->src_if4) ||
264 (a->addr.sa_family == AF_INET6 &&
265 b->addr.sa_family == AF_INET6 &&
266 a->addr6.sin6_port == b->addr6.sin6_port &&
267 ipv6_addr_equal(&a->addr6.sin6_addr, &b->addr6.sin6_addr) &&
268 a->addr6.sin6_scope_id == b->addr6.sin6_scope_id &&
269 ipv6_addr_equal(&a->src6, &b->src6)) ||
270 unlikely(!a->addr.sa_family && !b->addr.sa_family);
271 }
272
wg_socket_set_peer_endpoint(struct wg_peer * peer,const struct endpoint * endpoint)273 void wg_socket_set_peer_endpoint(struct wg_peer *peer,
274 const struct endpoint *endpoint)
275 {
276 /* First we check unlocked, in order to optimize, since it's pretty rare
277 * that an endpoint will change. If we happen to be mid-write, and two
278 * CPUs wind up writing the same thing or something slightly different,
279 * it doesn't really matter much either.
280 */
281 if (endpoint_eq(endpoint, &peer->endpoint))
282 return;
283 write_lock_bh(&peer->endpoint_lock);
284 if (endpoint->addr.sa_family == AF_INET) {
285 peer->endpoint.addr4 = endpoint->addr4;
286 peer->endpoint.src4 = endpoint->src4;
287 peer->endpoint.src_if4 = endpoint->src_if4;
288 } else if (IS_ENABLED(CONFIG_IPV6) && endpoint->addr.sa_family == AF_INET6) {
289 peer->endpoint.addr6 = endpoint->addr6;
290 peer->endpoint.src6 = endpoint->src6;
291 } else {
292 goto out;
293 }
294 dst_cache_reset(&peer->endpoint_cache);
295 out:
296 write_unlock_bh(&peer->endpoint_lock);
297 }
298
wg_socket_set_peer_endpoint_from_skb(struct wg_peer * peer,const struct sk_buff * skb)299 void wg_socket_set_peer_endpoint_from_skb(struct wg_peer *peer,
300 const struct sk_buff *skb)
301 {
302 struct endpoint endpoint;
303
304 if (!wg_socket_endpoint_from_skb(&endpoint, skb))
305 wg_socket_set_peer_endpoint(peer, &endpoint);
306 }
307
wg_socket_clear_peer_endpoint_src(struct wg_peer * peer)308 void wg_socket_clear_peer_endpoint_src(struct wg_peer *peer)
309 {
310 write_lock_bh(&peer->endpoint_lock);
311 memset(&peer->endpoint.src6, 0, sizeof(peer->endpoint.src6));
312 dst_cache_reset_now(&peer->endpoint_cache);
313 write_unlock_bh(&peer->endpoint_lock);
314 }
315
wg_receive(struct sock * sk,struct sk_buff * skb)316 static int wg_receive(struct sock *sk, struct sk_buff *skb)
317 {
318 struct wg_device *wg;
319
320 if (unlikely(!sk))
321 goto err;
322 wg = sk->sk_user_data;
323 if (unlikely(!wg))
324 goto err;
325 skb_mark_not_on_list(skb);
326 wg_packet_receive(wg, skb);
327 return 0;
328
329 err:
330 kfree_skb(skb);
331 return 0;
332 }
333
sock_free(struct sock * sock)334 static void sock_free(struct sock *sock)
335 {
336 if (unlikely(!sock))
337 return;
338 sk_clear_memalloc(sock);
339 udp_tunnel_sock_release(sock->sk_socket);
340 }
341
set_sock_opts(struct socket * sock)342 static void set_sock_opts(struct socket *sock)
343 {
344 sock->sk->sk_allocation = GFP_ATOMIC;
345 sock->sk->sk_sndbuf = INT_MAX;
346 sk_set_memalloc(sock->sk);
347 }
348
wg_socket_init(struct wg_device * wg,u16 port)349 int wg_socket_init(struct wg_device *wg, u16 port)
350 {
351 struct net *net;
352 int ret;
353 struct udp_tunnel_sock_cfg cfg = {
354 .sk_user_data = wg,
355 .encap_type = 1,
356 .encap_rcv = wg_receive
357 };
358 struct socket *new4 = NULL, *new6 = NULL;
359 struct udp_port_cfg port4 = {
360 .family = AF_INET,
361 .local_ip.s_addr = htonl(INADDR_ANY),
362 .local_udp_port = htons(port),
363 .use_udp_checksums = true
364 };
365 #if IS_ENABLED(CONFIG_IPV6)
366 int retries = 0;
367 struct udp_port_cfg port6 = {
368 .family = AF_INET6,
369 .local_ip6 = IN6ADDR_ANY_INIT,
370 .use_udp6_tx_checksums = true,
371 .use_udp6_rx_checksums = true,
372 .ipv6_v6only = true
373 };
374 #endif
375
376 rcu_read_lock();
377 net = rcu_dereference(wg->creating_net);
378 net = net ? maybe_get_net(net) : NULL;
379 rcu_read_unlock();
380 if (unlikely(!net))
381 return -ENONET;
382
383 #if IS_ENABLED(CONFIG_IPV6)
384 retry:
385 #endif
386
387 ret = udp_sock_create(net, &port4, &new4);
388 if (ret < 0) {
389 pr_err("%s: Could not create IPv4 socket\n", wg->dev->name);
390 goto out;
391 }
392 set_sock_opts(new4);
393 setup_udp_tunnel_sock(net, new4, &cfg);
394
395 #if IS_ENABLED(CONFIG_IPV6)
396 if (ipv6_mod_enabled()) {
397 port6.local_udp_port = inet_sk(new4->sk)->inet_sport;
398 ret = udp_sock_create(net, &port6, &new6);
399 if (ret < 0) {
400 udp_tunnel_sock_release(new4);
401 if (ret == -EADDRINUSE && !port && retries++ < 100)
402 goto retry;
403 pr_err("%s: Could not create IPv6 socket\n",
404 wg->dev->name);
405 goto out;
406 }
407 set_sock_opts(new6);
408 setup_udp_tunnel_sock(net, new6, &cfg);
409 }
410 #endif
411
412 wg_socket_reinit(wg, new4->sk, new6 ? new6->sk : NULL);
413 ret = 0;
414 out:
415 put_net(net);
416 return ret;
417 }
418
wg_socket_reinit(struct wg_device * wg,struct sock * new4,struct sock * new6)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_net();
435 sock_free(old4);
436 sock_free(old6);
437 }
438