drivers/net/wireguard/receive.c

   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 "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 /* Must be called with bh disabled. */
  20 static void update_rx_stats(struct wg_peer *peer, size_t len)
  21 {
  22         dev_sw_netstats_rx_add(peer->device->dev, len);
  23         peer->rx_bytes += len;
  24 }
  25
  26 #define SKB_TYPE_LE32(skb) (((struct message_header *)(skb)->data)->type)
  27
  28 static size_t validate_header_len(struct sk_buff *skb)
  29 {
  30         if (unlikely(skb->len < sizeof(struct message_header)))
  31                 return 0;
  32         if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_DATA) &&
  33             skb->len >= MESSAGE_MINIMUM_LENGTH)
  34                 return sizeof(struct message_data);
  35         if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION) &&
  36             skb->len == sizeof(struct message_handshake_initiation))
  37                 return sizeof(struct message_handshake_initiation);
  38         if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE) &&
  39             skb->len == sizeof(struct message_handshake_response))
  40                 return sizeof(struct message_handshake_response);
  41         if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE) &&
  42             skb->len == sizeof(struct message_handshake_cookie))
  43                 return sizeof(struct message_handshake_cookie);
  44         return 0;
  45 }
  46
  47 static int prepare_skb_header(struct sk_buff *skb, struct wg_device *wg)
  48 {
  49         size_t data_offset, data_len, header_len;
  50         struct udphdr *udp;
  51
  52         if (unlikely(!wg_check_packet_protocol(skb) ||
  53                      skb_transport_header(skb) < skb->head ||
  54                      (skb_transport_header(skb) + sizeof(struct udphdr)) >
  55                              skb_tail_pointer(skb)))
  56                 return -EINVAL; /* Bogus IP header */
  57         udp = udp_hdr(skb);
  58         data_offset = (u8 *)udp - skb->data;
  59         if (unlikely(data_offset > U16_MAX ||
  60                      data_offset + sizeof(struct udphdr) > skb->len))
  61                 /* Packet has offset at impossible location or isn't big enough
  62                  * to have UDP fields.
  63                  */
  64                 return -EINVAL;
  65         data_len = ntohs(udp->len);
  66         if (unlikely(data_len < sizeof(struct udphdr) ||
  67                      data_len > skb->len - data_offset))
  68                 /* UDP packet is reporting too small of a size or lying about
  69                  * its size.
  70                  */
  71                 return -EINVAL;
  72         data_len -= sizeof(struct udphdr);
  73         data_offset = (u8 *)udp + sizeof(struct udphdr) - skb->data;
  74         if (unlikely(!pskb_may_pull(skb,
  75                                 data_offset + sizeof(struct message_header)) ||
  76                      pskb_trim(skb, data_len + data_offset) < 0))
  77                 return -EINVAL;
  78         skb_pull(skb, data_offset);
  79         if (unlikely(skb->len != data_len))
  80                 /* Final len does not agree with calculated len */
  81                 return -EINVAL;
  82         header_len = validate_header_len(skb);
  83         if (unlikely(!header_len))
  84                 return -EINVAL;
  85         __skb_push(skb, data_offset);
  86         if (unlikely(!pskb_may_pull(skb, data_offset + header_len)))
  87                 return -EINVAL;
  88         __skb_pull(skb, data_offset);
  89         return 0;
  90 }
  91
  92 static void wg_receive_handshake_packet(struct wg_device *wg,
  93                                         struct sk_buff *skb)
  94 {
  95         enum cookie_mac_state mac_state;
  96         struct wg_peer *peer = NULL;
  97         /* This is global, so that our load calculation applies to the whole
  98          * system. We don't care about races with it at all.
  99          */
 100         static u64 last_under_load;
 101         bool packet_needs_cookie;
 102         bool under_load;
 103
 104         if (SKB_TYPE_LE32(skb) == cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE)) {
 105                 net_dbg_skb_ratelimited("%s: Receiving cookie response from %pISpfsc\n",
 106                                         wg->dev->name, skb);
 107                 wg_cookie_message_consume(
 108                         (struct message_handshake_cookie *)skb->data, wg);
 109                 return;
 110         }
 111
 112         under_load = atomic_read(&wg->handshake_queue_len) >=
 113                         MAX_QUEUED_INCOMING_HANDSHAKES / 8;
 114         if (under_load) {
 115                 last_under_load = ktime_get_coarse_boottime_ns();
 116         } else if (last_under_load) {
 117                 under_load = !wg_birthdate_has_expired(last_under_load, 1);
 118                 if (!under_load)
 119                         last_under_load = 0;
 120         }
 121         mac_state = wg_cookie_validate_packet(&wg->cookie_checker, skb,
 122                                               under_load);
 123         if ((under_load && mac_state == VALID_MAC_WITH_COOKIE) ||
 124             (!under_load && mac_state == VALID_MAC_BUT_NO_COOKIE)) {
 125                 packet_needs_cookie = false;
 126         } else if (under_load && mac_state == VALID_MAC_BUT_NO_COOKIE) {
 127                 packet_needs_cookie = true;
 128         } else {
 129                 net_dbg_skb_ratelimited("%s: Invalid MAC of handshake, dropping packet from %pISpfsc\n",
 130                                         wg->dev->name, skb);
 131                 return;
 132         }
 133
 134         switch (SKB_TYPE_LE32(skb)) {
 135         case cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION): {
 136                 struct message_handshake_initiation *message =
 137                         (struct message_handshake_initiation *)skb->data;
 138
 139                 if (packet_needs_cookie) {
 140                         wg_packet_send_handshake_cookie(wg, skb,
 141                                                         message->sender_index);
 142                         return;
 143                 }
 144                 peer = wg_noise_handshake_consume_initiation(message, wg);
 145                 if (unlikely(!peer)) {
 146                         net_dbg_skb_ratelimited("%s: Invalid handshake initiation from %pISpfsc\n",
 147                                                 wg->dev->name, skb);
 148                         return;
 149                 }
 150                 wg_socket_set_peer_endpoint_from_skb(peer, skb);
 151                 net_dbg_ratelimited("%s: Receiving handshake initiation from peer %llu (%pISpfsc)\n",
 152                                     wg->dev->name, peer->internal_id,
 153                                     &peer->endpoint.addr);
 154                 wg_packet_send_handshake_response(peer);
 155                 break;
 156         }
 157         case cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE): {
 158                 struct message_handshake_response *message =
 159                         (struct message_handshake_response *)skb->data;
 160
 161                 if (packet_needs_cookie) {
 162                         wg_packet_send_handshake_cookie(wg, skb,
 163                                                         message->sender_index);
 164                         return;
 165                 }
 166                 peer = wg_noise_handshake_consume_response(message, wg);
 167                 if (unlikely(!peer)) {
 168                         net_dbg_skb_ratelimited("%s: Invalid handshake response from %pISpfsc\n",
 169                                                 wg->dev->name, skb);
 170                         return;
 171                 }
 172                 wg_socket_set_peer_endpoint_from_skb(peer, skb);
 173                 net_dbg_ratelimited("%s: Receiving handshake response from peer %llu (%pISpfsc)\n",
 174                                     wg->dev->name, peer->internal_id,
 175                                     &peer->endpoint.addr);
 176                 if (wg_noise_handshake_begin_session(&peer->handshake,
 177                                                      &peer->keypairs)) {
 178                         wg_timers_session_derived(peer);
 179                         wg_timers_handshake_complete(peer);
 180                         /* Calling this function will either send any existing
 181                          * packets in the queue and not send a keepalive, which
 182                          * is the best case, Or, if there's nothing in the
 183                          * queue, it will send a keepalive, in order to give
 184                          * immediate confirmation of the session.
 185                          */
 186                         wg_packet_send_keepalive(peer);
 187                 }
 188                 break;
 189         }
 190         }
 191
 192         if (unlikely(!peer)) {
 193                 WARN(1, "Somehow a wrong type of packet wound up in the handshake queue!\n");
 194                 return;
 195         }
 196
 197         local_bh_disable();
 198         update_rx_stats(peer, skb->len);
 199         local_bh_enable();
 200
 201         wg_timers_any_authenticated_packet_received(peer);
 202         wg_timers_any_authenticated_packet_traversal(peer);
 203         wg_peer_put(peer);
 204 }
 205
 206 void wg_packet_handshake_receive_worker(struct work_struct *work)
 207 {
 208         struct crypt_queue *queue = container_of(work, struct multicore_worker, work)->ptr;
 209         struct wg_device *wg = container_of(queue, struct wg_device, handshake_queue);
 210         struct sk_buff *skb;
 211
 212         while ((skb = ptr_ring_consume_bh(&queue->ring)) != NULL) {
 213                 wg_receive_handshake_packet(wg, skb);
 214                 dev_kfree_skb(skb);
 215                 atomic_dec(&wg->handshake_queue_len);
 216                 cond_resched();
 217         }
 218 }
 219
 220 static void keep_key_fresh(struct wg_peer *peer)
 221 {
 222         struct noise_keypair *keypair;
 223         bool send;
 224
 225         if (peer->sent_lastminute_handshake)
 226                 return;
 227
 228         rcu_read_lock_bh();
 229         keypair = rcu_dereference_bh(peer->keypairs.current_keypair);
 230         send = keypair && READ_ONCE(keypair->sending.is_valid) &&
 231                keypair->i_am_the_initiator &&
 232                wg_birthdate_has_expired(keypair->sending.birthdate,
 233                         REJECT_AFTER_TIME - KEEPALIVE_TIMEOUT - REKEY_TIMEOUT);
 234         rcu_read_unlock_bh();
 235
 236         if (unlikely(send)) {
 237                 peer->sent_lastminute_handshake = true;
 238                 wg_packet_send_queued_handshake_initiation(peer, false);
 239         }
 240 }
 241
 242 static bool decrypt_packet(struct sk_buff *skb, struct noise_keypair *keypair)
 243 {
 244         struct scatterlist sg[MAX_SKB_FRAGS + 8];
 245         struct sk_buff *trailer;
 246         unsigned int offset;
 247         int num_frags;
 248
 249         if (unlikely(!keypair))
 250                 return false;
 251
 252         if (unlikely(!READ_ONCE(keypair->receiving.is_valid) ||
 253                   wg_birthdate_has_expired(keypair->receiving.birthdate, REJECT_AFTER_TIME) ||
 254                   keypair->receiving_counter.counter >= REJECT_AFTER_MESSAGES)) {
 255                 WRITE_ONCE(keypair->receiving.is_valid, false);
 256                 return false;
 257         }
 258
 259         PACKET_CB(skb)->nonce =
 260                 le64_to_cpu(((struct message_data *)skb->data)->counter);
 261
 262         /* We ensure that the network header is part of the packet before we
 263          * call skb_cow_data, so that there's no chance that data is removed
 264          * from the skb, so that later we can extract the original endpoint.
 265          */
 266         offset = -skb_network_offset(skb);
 267         skb_push(skb, offset);
 268         num_frags = skb_cow_data(skb, 0, &trailer);
 269         offset += sizeof(struct message_data);
 270         skb_pull(skb, offset);
 271         if (unlikely(num_frags < 0 || num_frags > ARRAY_SIZE(sg)))
 272                 return false;
 273
 274         sg_init_table(sg, num_frags);
 275         if (skb_to_sgvec(skb, sg, 0, skb->len) <= 0)
 276                 return false;
 277
 278         if (!chacha20poly1305_decrypt_sg_inplace(sg, skb->len, NULL, 0,
 279                                                  PACKET_CB(skb)->nonce,
 280                                                  keypair->receiving.key))
 281                 return false;
 282
 283         /* Another ugly situation of pushing and pulling the header so as to
 284          * keep endpoint information intact.
 285          */
 286         skb_push(skb, offset);
 287         if (pskb_trim(skb, skb->len - noise_encrypted_len(0)))
 288                 return false;
 289         skb_pull(skb, offset);
 290
 291         return true;
 292 }
 293
 294 /* This is RFC6479, a replay detection bitmap algorithm that avoids bitshifts */
 295 static bool counter_validate(struct noise_replay_counter *counter, u64 their_counter)
 296 {
 297         unsigned long index, index_current, top, i;
 298         bool ret = false;
 299
 300         spin_lock_bh(&counter->lock);
 301
 302         if (unlikely(counter->counter >= REJECT_AFTER_MESSAGES + 1 ||
 303                      their_counter >= REJECT_AFTER_MESSAGES))
 304                 goto out;
 305
 306         ++their_counter;
 307
 308         if (unlikely((COUNTER_WINDOW_SIZE + their_counter) <
 309                      counter->counter))
 310                 goto out;
 311
 312         index = their_counter >> ilog2(BITS_PER_LONG);
 313
 314         if (likely(their_counter > counter->counter)) {
 315                 index_current = counter->counter >> ilog2(BITS_PER_LONG);
 316                 top = min_t(unsigned long, index - index_current,
 317                             COUNTER_BITS_TOTAL / BITS_PER_LONG);
 318                 for (i = 1; i <= top; ++i)
 319                         counter->backtrack[(i + index_current) &
 320                                 ((COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1)] = 0;
 321                 counter->counter = their_counter;
 322         }
 323
 324         index &= (COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1;
 325         ret = !test_and_set_bit(their_counter & (BITS_PER_LONG - 1),
 326                                 &counter->backtrack[index]);
 327
 328 out:
 329         spin_unlock_bh(&counter->lock);
 330         return ret;
 331 }
 332
 333 #include "selftest/counter.c"
 334
 335 static void wg_packet_consume_data_done(struct wg_peer *peer,
 336                                         struct sk_buff *skb,
 337                                         struct endpoint *endpoint)
 338 {
 339         struct net_device *dev = peer->device->dev;
 340         unsigned int len, len_before_trim;
 341         struct wg_peer *routed_peer;
 342
 343         wg_socket_set_peer_endpoint(peer, endpoint);
 344
 345         if (unlikely(wg_noise_received_with_keypair(&peer->keypairs,
 346                                                     PACKET_CB(skb)->keypair))) {
 347                 wg_timers_handshake_complete(peer);
 348                 wg_packet_send_staged_packets(peer);
 349         }
 350
 351         keep_key_fresh(peer);
 352
 353         wg_timers_any_authenticated_packet_received(peer);
 354         wg_timers_any_authenticated_packet_traversal(peer);
 355
 356         /* A packet with length 0 is a keepalive packet */
 357         if (unlikely(!skb->len)) {
 358                 update_rx_stats(peer, message_data_len(0));
 359                 net_dbg_ratelimited("%s: Receiving keepalive packet from peer %llu (%pISpfsc)\n",
 360                                     dev->name, peer->internal_id,
 361                                     &peer->endpoint.addr);
 362                 goto packet_processed;
 363         }
 364
 365         wg_timers_data_received(peer);
 366
 367         if (unlikely(skb_network_header(skb) < skb->head))
 368                 goto dishonest_packet_size;
 369         if (unlikely(!(pskb_network_may_pull(skb, sizeof(struct iphdr)) &&
 370                        (ip_hdr(skb)->version == 4 ||
 371                         (ip_hdr(skb)->version == 6 &&
 372                          pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))))))
 373                 goto dishonest_packet_type;
 374
 375         skb->dev = dev;
 376         /* We've already verified the Poly1305 auth tag, which means this packet
 377          * was not modified in transit. We can therefore tell the networking
 378          * stack that all checksums of every layer of encapsulation have already
 379          * been checked "by the hardware" and therefore is unnecessary to check
 380          * again in software.
 381          */
 382         skb->ip_summed = CHECKSUM_UNNECESSARY;
 383         skb->csum_level = ~0; /* All levels */
 384         skb->protocol = ip_tunnel_parse_protocol(skb);
 385         if (skb->protocol == htons(ETH_P_IP)) {
 386                 len = ntohs(ip_hdr(skb)->tot_len);
 387                 if (unlikely(len < sizeof(struct iphdr)))
 388                         goto dishonest_packet_size;
 389                 INET_ECN_decapsulate(skb, PACKET_CB(skb)->ds, ip_hdr(skb)->tos);
 390         } else if (skb->protocol == htons(ETH_P_IPV6)) {
 391                 len = ntohs(ipv6_hdr(skb)->payload_len) +
 392                       sizeof(struct ipv6hdr);
 393                 INET_ECN_decapsulate(skb, PACKET_CB(skb)->ds, ipv6_get_dsfield(ipv6_hdr(skb)));
 394         } else {
 395                 goto dishonest_packet_type;
 396         }
 397
 398         if (unlikely(len > skb->len))
 399                 goto dishonest_packet_size;
 400         len_before_trim = skb->len;
 401         if (unlikely(pskb_trim(skb, len)))
 402                 goto packet_processed;
 403
 404         routed_peer = wg_allowedips_lookup_src(&peer->device->peer_allowedips,
 405                                                skb);
 406         wg_peer_put(routed_peer); /* We don't need the extra reference. */
 407
 408         if (unlikely(routed_peer != peer))
 409                 goto dishonest_packet_peer;
 410
 411         napi_gro_receive(&peer->napi, skb);
 412         update_rx_stats(peer, message_data_len(len_before_trim));
 413         return;
 414
 415 dishonest_packet_peer:
 416         net_dbg_skb_ratelimited("%s: Packet has unallowed src IP (%pISc) from peer %llu (%pISpfsc)\n",
 417                                 dev->name, skb, peer->internal_id,
 418                                 &peer->endpoint.addr);
 419         DEV_STATS_INC(dev, rx_errors);
 420         DEV_STATS_INC(dev, rx_frame_errors);
 421         goto packet_processed;
 422 dishonest_packet_type:
 423         net_dbg_ratelimited("%s: Packet is neither ipv4 nor ipv6 from peer %llu (%pISpfsc)\n",
 424                             dev->name, peer->internal_id, &peer->endpoint.addr);
 425         DEV_STATS_INC(dev, rx_errors);
 426         DEV_STATS_INC(dev, rx_frame_errors);
 427         goto packet_processed;
 428 dishonest_packet_size:
 429         net_dbg_ratelimited("%s: Packet has incorrect size from peer %llu (%pISpfsc)\n",
 430                             dev->name, peer->internal_id, &peer->endpoint.addr);
 431         DEV_STATS_INC(dev, rx_errors);
 432         DEV_STATS_INC(dev, rx_length_errors);
 433         goto packet_processed;
 434 packet_processed:
 435         dev_kfree_skb(skb);
 436 }
 437
 438 int wg_packet_rx_poll(struct napi_struct *napi, int budget)
 439 {
 440         struct wg_peer *peer = container_of(napi, struct wg_peer, napi);
 441         struct noise_keypair *keypair;
 442         struct endpoint endpoint;
 443         enum packet_state state;
 444         struct sk_buff *skb;
 445         int work_done = 0;
 446         bool free;
 447
 448         if (unlikely(budget <= 0))
 449                 return 0;
 450
 451         while ((skb = wg_prev_queue_peek(&peer->rx_queue)) != NULL &&
 452                (state = atomic_read_acquire(&PACKET_CB(skb)->state)) !=
 453                        PACKET_STATE_UNCRYPTED) {
 454                 wg_prev_queue_drop_peeked(&peer->rx_queue);
 455                 keypair = PACKET_CB(skb)->keypair;
 456                 free = true;
 457
 458                 if (unlikely(state != PACKET_STATE_CRYPTED))
 459                         goto next;
 460
 461                 if (unlikely(!counter_validate(&keypair->receiving_counter,
 462                                                PACKET_CB(skb)->nonce))) {
 463                         net_dbg_ratelimited("%s: Packet has invalid nonce %llu (max %llu)\n",
 464                                             peer->device->dev->name,
 465                                             PACKET_CB(skb)->nonce,
 466                                             keypair->receiving_counter.counter);
 467                         goto next;
 468                 }
 469
 470                 if (unlikely(wg_socket_endpoint_from_skb(&endpoint, skb)))
 471                         goto next;
 472
 473                 wg_reset_packet(skb, false);
 474                 wg_packet_consume_data_done(peer, skb, &endpoint);
 475                 free = false;
 476
 477 next:
 478                 wg_noise_keypair_put(keypair, false);
 479                 wg_peer_put(peer);
 480                 if (unlikely(free))
 481                         dev_kfree_skb(skb);
 482
 483                 if (++work_done >= budget)
 484                         break;
 485         }
 486
 487         if (work_done < budget)
 488                 napi_complete_done(napi, work_done);
 489
 490         return work_done;
 491 }
 492
 493 void wg_packet_decrypt_worker(struct work_struct *work)
 494 {
 495         struct crypt_queue *queue = container_of(work, struct multicore_worker,
 496                                                  work)->ptr;
 497         struct sk_buff *skb;
 498
 499         while ((skb = ptr_ring_consume_bh(&queue->ring)) != NULL) {
 500                 enum packet_state state =
 501                         likely(decrypt_packet(skb, PACKET_CB(skb)->keypair)) ?
 502                                 PACKET_STATE_CRYPTED : PACKET_STATE_DEAD;
 503                 wg_queue_enqueue_per_peer_rx(skb, state);
 504                 if (need_resched())
 505                         cond_resched();
 506         }
 507 }
 508
 509 static void wg_packet_consume_data(struct wg_device *wg, struct sk_buff *skb)
 510 {
 511         __le32 idx = ((struct message_data *)skb->data)->key_idx;
 512         struct wg_peer *peer = NULL;
 513         int ret;
 514
 515         rcu_read_lock_bh();
 516         PACKET_CB(skb)->keypair =
 517                 (struct noise_keypair *)wg_index_hashtable_lookup(
 518                         wg->index_hashtable, INDEX_HASHTABLE_KEYPAIR, idx,
 519                         &peer);
 520         if (unlikely(!wg_noise_keypair_get(PACKET_CB(skb)->keypair)))
 521                 goto err_keypair;
 522
 523         if (unlikely(READ_ONCE(peer->is_dead)))
 524                 goto err;
 525
 526         ret = wg_queue_enqueue_per_device_and_peer(&wg->decrypt_queue, &peer->rx_queue, skb,
 527                                                    wg->packet_crypt_wq);
 528         if (unlikely(ret == -EPIPE))
 529                 wg_queue_enqueue_per_peer_rx(skb, PACKET_STATE_DEAD);
 530         if (likely(!ret || ret == -EPIPE)) {
 531                 rcu_read_unlock_bh();
 532                 return;
 533         }
 534 err:
 535         wg_noise_keypair_put(PACKET_CB(skb)->keypair, false);
 536 err_keypair:
 537         rcu_read_unlock_bh();
 538         wg_peer_put(peer);
 539         dev_kfree_skb(skb);
 540 }
 541
 542 void wg_packet_receive(struct wg_device *wg, struct sk_buff *skb)
 543 {
 544         if (unlikely(prepare_skb_header(skb, wg) < 0))
 545                 goto err;
 546         switch (SKB_TYPE_LE32(skb)) {
 547         case cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION):
 548         case cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE):
 549         case cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE): {
 550                 int cpu, ret = -EBUSY;
 551
 552                 if (unlikely(!rng_is_initialized()))
 553                         goto drop;
 554                 if (atomic_read(&wg->handshake_queue_len) > MAX_QUEUED_INCOMING_HANDSHAKES / 2) {
 555                         if (spin_trylock_bh(&wg->handshake_queue.ring.producer_lock)) {
 556                                 ret = __ptr_ring_produce(&wg->handshake_queue.ring, skb);
 557                                 spin_unlock_bh(&wg->handshake_queue.ring.producer_lock);
 558                         }
 559                 } else
 560                         ret = ptr_ring_produce_bh(&wg->handshake_queue.ring, skb);
 561                 if (ret) {
 562         drop:
 563                         net_dbg_skb_ratelimited("%s: Dropping handshake packet from %pISpfsc\n",
 564                                                 wg->dev->name, skb);
 565                         goto err;
 566                 }
 567                 atomic_inc(&wg->handshake_queue_len);
 568                 cpu = wg_cpumask_next_online(&wg->handshake_queue.last_cpu);
 569                 /* Queues up a call to packet_process_queued_handshake_packets(skb): */
 570                 queue_work_on(cpu, wg->handshake_receive_wq,
 571                               &per_cpu_ptr(wg->handshake_queue.worker, cpu)->work);
 572                 break;
 573         }
 574         case cpu_to_le32(MESSAGE_DATA):
 575                 PACKET_CB(skb)->ds = ip_tunnel_get_dsfield(ip_hdr(skb), skb);
 576                 wg_packet_consume_data(wg, skb);
 577                 break;
 578         default:
 579                 WARN(1, "Non-exhaustive parsing of packet header lead to unknown packet type!\n");
 580                 goto err;
 581         }
 582         return;
 583
 584 err:
 585         dev_kfree_skb(skb);
 586 }