1
2
3
4
5
6#include "queueing.h"
7#include "device.h"
8#include "peer.h"
9#include "timers.h"
10#include "messages.h"
11#include "cookie.h"
12#include "socket.h"
13
14#include <linux/ip.h>
15#include <linux/ipv6.h>
16#include <linux/udp.h>
17#include <net/ip_tunnels.h>
18
19
20static void update_rx_stats(struct wg_peer *peer, size_t len)
21{
22 struct pcpu_sw_netstats *tstats =
23 get_cpu_ptr(peer->device->dev->tstats);
24
25 u64_stats_update_begin(&tstats->syncp);
26 ++tstats->rx_packets;
27 tstats->rx_bytes += len;
28 peer->rx_bytes += len;
29 u64_stats_update_end(&tstats->syncp);
30 put_cpu_ptr(tstats);
31}
32
33#define SKB_TYPE_LE32(skb) (((struct message_header *)(skb)->data)->type)
34
35static size_t validate_header_len(struct sk_buff *skb)
36{
37 if (unlikely(skb->len < sizeof(struct message_header)))
38 return 0;
39 if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_DATA) &&
40 skb->len >= MESSAGE_MINIMUM_LENGTH)
41 return sizeof(struct message_data);
42 if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION) &&
43 skb->len == sizeof(struct message_handshake_initiation))
44 return sizeof(struct message_handshake_initiation);
45 if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE) &&
46 skb->len == sizeof(struct message_handshake_response))
47 return sizeof(struct message_handshake_response);
48 if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE) &&
49 skb->len == sizeof(struct message_handshake_cookie))
50 return sizeof(struct message_handshake_cookie);
51 return 0;
52}
53
54static int prepare_skb_header(struct sk_buff *skb, struct wg_device *wg)
55{
56 size_t data_offset, data_len, header_len;
57 struct udphdr *udp;
58
59 if (unlikely(!wg_check_packet_protocol(skb) ||
60 skb_transport_header(skb) < skb->head ||
61 (skb_transport_header(skb) + sizeof(struct udphdr)) >
62 skb_tail_pointer(skb)))
63 return -EINVAL;
64 udp = udp_hdr(skb);
65 data_offset = (u8 *)udp - skb->data;
66 if (unlikely(data_offset > U16_MAX ||
67 data_offset + sizeof(struct udphdr) > skb->len))
68
69
70
71 return -EINVAL;
72 data_len = ntohs(udp->len);
73 if (unlikely(data_len < sizeof(struct udphdr) ||
74 data_len > skb->len - data_offset))
75
76
77
78 return -EINVAL;
79 data_len -= sizeof(struct udphdr);
80 data_offset = (u8 *)udp + sizeof(struct udphdr) - skb->data;
81 if (unlikely(!pskb_may_pull(skb,
82 data_offset + sizeof(struct message_header)) ||
83 pskb_trim(skb, data_len + data_offset) < 0))
84 return -EINVAL;
85 skb_pull(skb, data_offset);
86 if (unlikely(skb->len != data_len))
87
88 return -EINVAL;
89 header_len = validate_header_len(skb);
90 if (unlikely(!header_len))
91 return -EINVAL;
92 __skb_push(skb, data_offset);
93 if (unlikely(!pskb_may_pull(skb, data_offset + header_len)))
94 return -EINVAL;
95 __skb_pull(skb, data_offset);
96 return 0;
97}
98
99static void wg_receive_handshake_packet(struct wg_device *wg,
100 struct sk_buff *skb)
101{
102 enum cookie_mac_state mac_state;
103 struct wg_peer *peer = NULL;
104
105
106
107 static u64 last_under_load;
108 bool packet_needs_cookie;
109 bool under_load;
110
111 if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE)) {
112 net_dbg_skb_ratelimited("%s: Receiving cookie response from %pISpfsc\n",
113 wg->dev->name, skb);
114 wg_cookie_message_consume(
115 (struct message_handshake_cookie *)skb->data, wg);
116 return;
117 }
118
119 under_load = skb_queue_len(&wg->incoming_handshakes) >=
120 MAX_QUEUED_INCOMING_HANDSHAKES / 8;
121 if (under_load) {
122 last_under_load = ktime_get_coarse_boottime_ns();
123 } else if (last_under_load) {
124 under_load = !wg_birthdate_has_expired(last_under_load, 1);
125 if (!under_load)
126 last_under_load = 0;
127 }
128 mac_state = wg_cookie_validate_packet(&wg->cookie_checker, skb,
129 under_load);
130 if ((under_load && mac_state == VALID_MAC_WITH_COOKIE) ||
131 (!under_load && mac_state == VALID_MAC_BUT_NO_COOKIE)) {
132 packet_needs_cookie = false;
133 } else if (under_load && mac_state == VALID_MAC_BUT_NO_COOKIE) {
134 packet_needs_cookie = true;
135 } else {
136 net_dbg_skb_ratelimited("%s: Invalid MAC of handshake, dropping packet from %pISpfsc\n",
137 wg->dev->name, skb);
138 return;
139 }
140
141 switch (SKB_TYPE_LE32(skb)) {
142 case cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION): {
143 struct message_handshake_initiation *message =
144 (struct message_handshake_initiation *)skb->data;
145
146 if (packet_needs_cookie) {
147 wg_packet_send_handshake_cookie(wg, skb,
148 message->sender_index);
149 return;
150 }
151 peer = wg_noise_handshake_consume_initiation(message, wg);
152 if (unlikely(!peer)) {
153 net_dbg_skb_ratelimited("%s: Invalid handshake initiation from %pISpfsc\n",
154 wg->dev->name, skb);
155 return;
156 }
157 wg_socket_set_peer_endpoint_from_skb(peer, skb);
158 net_dbg_ratelimited("%s: Receiving handshake initiation from peer %llu (%pISpfsc)\n",
159 wg->dev->name, peer->internal_id,
160 &peer->endpoint.addr);
161 wg_packet_send_handshake_response(peer);
162 break;
163 }
164 case cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE): {
165 struct message_handshake_response *message =
166 (struct message_handshake_response *)skb->data;
167
168 if (packet_needs_cookie) {
169 wg_packet_send_handshake_cookie(wg, skb,
170 message->sender_index);
171 return;
172 }
173 peer = wg_noise_handshake_consume_response(message, wg);
174 if (unlikely(!peer)) {
175 net_dbg_skb_ratelimited("%s: Invalid handshake response from %pISpfsc\n",
176 wg->dev->name, skb);
177 return;
178 }
179 wg_socket_set_peer_endpoint_from_skb(peer, skb);
180 net_dbg_ratelimited("%s: Receiving handshake response from peer %llu (%pISpfsc)\n",
181 wg->dev->name, peer->internal_id,
182 &peer->endpoint.addr);
183 if (wg_noise_handshake_begin_session(&peer->handshake,
184 &peer->keypairs)) {
185 wg_timers_session_derived(peer);
186 wg_timers_handshake_complete(peer);
187
188
189
190
191
192
193 wg_packet_send_keepalive(peer);
194 }
195 break;
196 }
197 }
198
199 if (unlikely(!peer)) {
200 WARN(1, "Somehow a wrong type of packet wound up in the handshake queue!\n");
201 return;
202 }
203
204 local_bh_disable();
205 update_rx_stats(peer, skb->len);
206 local_bh_enable();
207
208 wg_timers_any_authenticated_packet_received(peer);
209 wg_timers_any_authenticated_packet_traversal(peer);
210 wg_peer_put(peer);
211}
212
213void wg_packet_handshake_receive_worker(struct work_struct *work)
214{
215 struct wg_device *wg = container_of(work, struct multicore_worker,
216 work)->ptr;
217 struct sk_buff *skb;
218
219 while ((skb = skb_dequeue(&wg->incoming_handshakes)) != NULL) {
220 wg_receive_handshake_packet(wg, skb);
221 dev_kfree_skb(skb);
222 cond_resched();
223 }
224}
225
226static void keep_key_fresh(struct wg_peer *peer)
227{
228 struct noise_keypair *keypair;
229 bool send = false;
230
231 if (peer->sent_lastminute_handshake)
232 return;
233
234 rcu_read_lock_bh();
235 keypair = rcu_dereference_bh(peer->keypairs.current_keypair);
236 if (likely(keypair && READ_ONCE(keypair->sending.is_valid)) &&
237 keypair->i_am_the_initiator &&
238 unlikely(wg_birthdate_has_expired(keypair->sending.birthdate,
239 REJECT_AFTER_TIME - KEEPALIVE_TIMEOUT - REKEY_TIMEOUT)))
240 send = true;
241 rcu_read_unlock_bh();
242
243 if (send) {
244 peer->sent_lastminute_handshake = true;
245 wg_packet_send_queued_handshake_initiation(peer, false);
246 }
247}
248
249static bool decrypt_packet(struct sk_buff *skb, struct noise_symmetric_key *key)
250{
251 struct scatterlist sg[MAX_SKB_FRAGS + 8];
252 struct sk_buff *trailer;
253 unsigned int offset;
254 int num_frags;
255
256 if (unlikely(!key))
257 return false;
258
259 if (unlikely(!READ_ONCE(key->is_valid) ||
260 wg_birthdate_has_expired(key->birthdate, REJECT_AFTER_TIME) ||
261 key->counter.receive.counter >= REJECT_AFTER_MESSAGES)) {
262 WRITE_ONCE(key->is_valid, false);
263 return false;
264 }
265
266 PACKET_CB(skb)->nonce =
267 le64_to_cpu(((struct message_data *)skb->data)->counter);
268
269
270
271
272
273 offset = skb->data - skb_network_header(skb);
274 skb_push(skb, offset);
275 num_frags = skb_cow_data(skb, 0, &trailer);
276 offset += sizeof(struct message_data);
277 skb_pull(skb, offset);
278 if (unlikely(num_frags < 0 || num_frags > ARRAY_SIZE(sg)))
279 return false;
280
281 sg_init_table(sg, num_frags);
282 if (skb_to_sgvec(skb, sg, 0, skb->len) <= 0)
283 return false;
284
285 if (!chacha20poly1305_decrypt_sg_inplace(sg, skb->len, NULL, 0,
286 PACKET_CB(skb)->nonce,
287 key->key))
288 return false;
289
290
291
292
293 skb_push(skb, offset);
294 if (pskb_trim(skb, skb->len - noise_encrypted_len(0)))
295 return false;
296 skb_pull(skb, offset);
297
298 return true;
299}
300
301
302static bool counter_validate(union noise_counter *counter, u64 their_counter)
303{
304 unsigned long index, index_current, top, i;
305 bool ret = false;
306
307 spin_lock_bh(&counter->receive.lock);
308
309 if (unlikely(counter->receive.counter >= REJECT_AFTER_MESSAGES + 1 ||
310 their_counter >= REJECT_AFTER_MESSAGES))
311 goto out;
312
313 ++their_counter;
314
315 if (unlikely((COUNTER_WINDOW_SIZE + their_counter) <
316 counter->receive.counter))
317 goto out;
318
319 index = their_counter >> ilog2(BITS_PER_LONG);
320
321 if (likely(their_counter > counter->receive.counter)) {
322 index_current = counter->receive.counter >> ilog2(BITS_PER_LONG);
323 top = min_t(unsigned long, index - index_current,
324 COUNTER_BITS_TOTAL / BITS_PER_LONG);
325 for (i = 1; i <= top; ++i)
326 counter->receive.backtrack[(i + index_current) &
327 ((COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1)] = 0;
328 counter->receive.counter = their_counter;
329 }
330
331 index &= (COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1;
332 ret = !test_and_set_bit(their_counter & (BITS_PER_LONG - 1),
333 &counter->receive.backtrack[index]);
334
335out:
336 spin_unlock_bh(&counter->receive.lock);
337 return ret;
338}
339
340#include "selftest/counter.c"
341
342static void wg_packet_consume_data_done(struct wg_peer *peer,
343 struct sk_buff *skb,
344 struct endpoint *endpoint)
345{
346 struct net_device *dev = peer->device->dev;
347 unsigned int len, len_before_trim;
348 struct wg_peer *routed_peer;
349
350 wg_socket_set_peer_endpoint(peer, endpoint);
351
352 if (unlikely(wg_noise_received_with_keypair(&peer->keypairs,
353 PACKET_CB(skb)->keypair))) {
354 wg_timers_handshake_complete(peer);
355 wg_packet_send_staged_packets(peer);
356 }
357
358 keep_key_fresh(peer);
359
360 wg_timers_any_authenticated_packet_received(peer);
361 wg_timers_any_authenticated_packet_traversal(peer);
362
363
364 if (unlikely(!skb->len)) {
365 update_rx_stats(peer, message_data_len(0));
366 net_dbg_ratelimited("%s: Receiving keepalive packet from peer %llu (%pISpfsc)\n",
367 dev->name, peer->internal_id,
368 &peer->endpoint.addr);
369 goto packet_processed;
370 }
371
372 wg_timers_data_received(peer);
373
374 if (unlikely(skb_network_header(skb) < skb->head))
375 goto dishonest_packet_size;
376 if (unlikely(!(pskb_network_may_pull(skb, sizeof(struct iphdr)) &&
377 (ip_hdr(skb)->version == 4 ||
378 (ip_hdr(skb)->version == 6 &&
379 pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))))))
380 goto dishonest_packet_type;
381
382 skb->dev = dev;
383
384
385
386
387
388
389 skb->ip_summed = CHECKSUM_UNNECESSARY;
390 skb->csum_level = ~0;
391 skb->protocol = wg_examine_packet_protocol(skb);
392 if (skb->protocol == htons(ETH_P_IP)) {
393 len = ntohs(ip_hdr(skb)->tot_len);
394 if (unlikely(len < sizeof(struct iphdr)))
395 goto dishonest_packet_size;
396 if (INET_ECN_is_ce(PACKET_CB(skb)->ds))
397 IP_ECN_set_ce(ip_hdr(skb));
398 } else if (skb->protocol == htons(ETH_P_IPV6)) {
399 len = ntohs(ipv6_hdr(skb)->payload_len) +
400 sizeof(struct ipv6hdr);
401 if (INET_ECN_is_ce(PACKET_CB(skb)->ds))
402 IP6_ECN_set_ce(skb, ipv6_hdr(skb));
403 } else {
404 goto dishonest_packet_type;
405 }
406
407 if (unlikely(len > skb->len))
408 goto dishonest_packet_size;
409 len_before_trim = skb->len;
410 if (unlikely(pskb_trim(skb, len)))
411 goto packet_processed;
412
413 routed_peer = wg_allowedips_lookup_src(&peer->device->peer_allowedips,
414 skb);
415 wg_peer_put(routed_peer);
416
417 if (unlikely(routed_peer != peer))
418 goto dishonest_packet_peer;
419
420 if (unlikely(napi_gro_receive(&peer->napi, skb) == GRO_DROP)) {
421 ++dev->stats.rx_dropped;
422 net_dbg_ratelimited("%s: Failed to give packet to userspace from peer %llu (%pISpfsc)\n",
423 dev->name, peer->internal_id,
424 &peer->endpoint.addr);
425 } else {
426 update_rx_stats(peer, message_data_len(len_before_trim));
427 }
428 return;
429
430dishonest_packet_peer:
431 net_dbg_skb_ratelimited("%s: Packet has unallowed src IP (%pISc) from peer %llu (%pISpfsc)\n",
432 dev->name, skb, peer->internal_id,
433 &peer->endpoint.addr);
434 ++dev->stats.rx_errors;
435 ++dev->stats.rx_frame_errors;
436 goto packet_processed;
437dishonest_packet_type:
438 net_dbg_ratelimited("%s: Packet is neither ipv4 nor ipv6 from peer %llu (%pISpfsc)\n",
439 dev->name, peer->internal_id, &peer->endpoint.addr);
440 ++dev->stats.rx_errors;
441 ++dev->stats.rx_frame_errors;
442 goto packet_processed;
443dishonest_packet_size:
444 net_dbg_ratelimited("%s: Packet has incorrect size from peer %llu (%pISpfsc)\n",
445 dev->name, peer->internal_id, &peer->endpoint.addr);
446 ++dev->stats.rx_errors;
447 ++dev->stats.rx_length_errors;
448 goto packet_processed;
449packet_processed:
450 dev_kfree_skb(skb);
451}
452
453int wg_packet_rx_poll(struct napi_struct *napi, int budget)
454{
455 struct wg_peer *peer = container_of(napi, struct wg_peer, napi);
456 struct crypt_queue *queue = &peer->rx_queue;
457 struct noise_keypair *keypair;
458 struct endpoint endpoint;
459 enum packet_state state;
460 struct sk_buff *skb;
461 int work_done = 0;
462 bool free;
463
464 if (unlikely(budget <= 0))
465 return 0;
466
467 while ((skb = __ptr_ring_peek(&queue->ring)) != NULL &&
468 (state = atomic_read_acquire(&PACKET_CB(skb)->state)) !=
469 PACKET_STATE_UNCRYPTED) {
470 __ptr_ring_discard_one(&queue->ring);
471 peer = PACKET_PEER(skb);
472 keypair = PACKET_CB(skb)->keypair;
473 free = true;
474
475 if (unlikely(state != PACKET_STATE_CRYPTED))
476 goto next;
477
478 if (unlikely(!counter_validate(&keypair->receiving.counter,
479 PACKET_CB(skb)->nonce))) {
480 net_dbg_ratelimited("%s: Packet has invalid nonce %llu (max %llu)\n",
481 peer->device->dev->name,
482 PACKET_CB(skb)->nonce,
483 keypair->receiving.counter.receive.counter);
484 goto next;
485 }
486
487 if (unlikely(wg_socket_endpoint_from_skb(&endpoint, skb)))
488 goto next;
489
490 wg_reset_packet(skb);
491 wg_packet_consume_data_done(peer, skb, &endpoint);
492 free = false;
493
494next:
495 wg_noise_keypair_put(keypair, false);
496 wg_peer_put(peer);
497 if (unlikely(free))
498 dev_kfree_skb(skb);
499
500 if (++work_done >= budget)
501 break;
502 }
503
504 if (work_done < budget)
505 napi_complete_done(napi, work_done);
506
507 return work_done;
508}
509
510void wg_packet_decrypt_worker(struct work_struct *work)
511{
512 struct crypt_queue *queue = container_of(work, struct multicore_worker,
513 work)->ptr;
514 struct sk_buff *skb;
515
516 while ((skb = ptr_ring_consume_bh(&queue->ring)) != NULL) {
517 enum packet_state state = likely(decrypt_packet(skb,
518 &PACKET_CB(skb)->keypair->receiving)) ?
519 PACKET_STATE_CRYPTED : PACKET_STATE_DEAD;
520 wg_queue_enqueue_per_peer_napi(skb, state);
521 }
522}
523
524static void wg_packet_consume_data(struct wg_device *wg, struct sk_buff *skb)
525{
526 __le32 idx = ((struct message_data *)skb->data)->key_idx;
527 struct wg_peer *peer = NULL;
528 int ret;
529
530 rcu_read_lock_bh();
531 PACKET_CB(skb)->keypair =
532 (struct noise_keypair *)wg_index_hashtable_lookup(
533 wg->index_hashtable, INDEX_HASHTABLE_KEYPAIR, idx,
534 &peer);
535 if (unlikely(!wg_noise_keypair_get(PACKET_CB(skb)->keypair)))
536 goto err_keypair;
537
538 if (unlikely(READ_ONCE(peer->is_dead)))
539 goto err;
540
541 ret = wg_queue_enqueue_per_device_and_peer(&wg->decrypt_queue,
542 &peer->rx_queue, skb,
543 wg->packet_crypt_wq,
544 &wg->decrypt_queue.last_cpu);
545 if (unlikely(ret == -EPIPE))
546 wg_queue_enqueue_per_peer_napi(skb, PACKET_STATE_DEAD);
547 if (likely(!ret || ret == -EPIPE)) {
548 rcu_read_unlock_bh();
549 return;
550 }
551err:
552 wg_noise_keypair_put(PACKET_CB(skb)->keypair, false);
553err_keypair:
554 rcu_read_unlock_bh();
555 wg_peer_put(peer);
556 dev_kfree_skb(skb);
557}
558
559void wg_packet_receive(struct wg_device *wg, struct sk_buff *skb)
560{
561 if (unlikely(prepare_skb_header(skb, wg) < 0))
562 goto err;
563 switch (SKB_TYPE_LE32(skb)) {
564 case cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION):
565 case cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE):
566 case cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE): {
567 int cpu;
568
569 if (skb_queue_len(&wg->incoming_handshakes) >
570 MAX_QUEUED_INCOMING_HANDSHAKES ||
571 unlikely(!rng_is_initialized())) {
572 net_dbg_skb_ratelimited("%s: Dropping handshake packet from %pISpfsc\n",
573 wg->dev->name, skb);
574 goto err;
575 }
576 skb_queue_tail(&wg->incoming_handshakes, skb);
577
578
579
580 cpu = wg_cpumask_next_online(&wg->incoming_handshake_cpu);
581 queue_work_on(cpu, wg->handshake_receive_wq,
582 &per_cpu_ptr(wg->incoming_handshakes_worker, cpu)->work);
583 break;
584 }
585 case cpu_to_le32(MESSAGE_DATA):
586 PACKET_CB(skb)->ds = ip_tunnel_get_dsfield(ip_hdr(skb), skb);
587 wg_packet_consume_data(wg, skb);
588 break;
589 default:
590 WARN(1, "Non-exhaustive parsing of packet header lead to unknown packet type!\n");
591 goto err;
592 }
593 return;
594
595err:
596 dev_kfree_skb(skb);
597}
598
