drivers/net/wireguard/device.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 "socket.h"
   8 #include "timers.h"
   9 #include "device.h"
  10 #include "ratelimiter.h"
  11 #include "peer.h"
  12 #include "messages.h"
  13
  14 #include <linux/module.h>
  15 #include <linux/rtnetlink.h>
  16 #include <linux/inet.h>
  17 #include <linux/netdevice.h>
  18 #include <linux/inetdevice.h>
  19 #include <linux/if_arp.h>
  20 #include <linux/icmp.h>
  21 #include <linux/suspend.h>
  22 #include <net/dst_metadata.h>
  23 #include <net/gso.h>
  24 #include <net/icmp.h>
  25 #include <net/rtnetlink.h>
  26 #include <net/ip_tunnels.h>
  27 #include <net/addrconf.h>
  28
  29 static LIST_HEAD(device_list);
  30
  31 static int wg_open(struct net_device *dev)
  32 {
  33         struct in_device *dev_v4 = __in_dev_get_rtnl(dev);
  34         struct inet6_dev *dev_v6 = __in6_dev_get(dev);
  35         struct wg_device *wg = netdev_priv(dev);
  36         struct wg_peer *peer;
  37         int ret;
  38
  39         if (dev_v4) {
  40                 /* At some point we might put this check near the ip_rt_send_
  41                  * redirect call of ip_forward in net/ipv4/ip_forward.c, similar
  42                  * to the current secpath check.
  43                  */
  44                 IN_DEV_CONF_SET(dev_v4, SEND_REDIRECTS, false);
  45                 IPV4_DEVCONF_ALL(dev_net(dev), SEND_REDIRECTS) = false;
  46         }
  47         if (dev_v6)
  48                 dev_v6->cnf.addr_gen_mode = IN6_ADDR_GEN_MODE_NONE;
  49
  50         mutex_lock(&wg->device_update_lock);
  51         ret = wg_socket_init(wg, wg->incoming_port);
  52         if (ret < 0)
  53                 goto out;
  54         list_for_each_entry(peer, &wg->peer_list, peer_list) {
  55                 wg_packet_send_staged_packets(peer);
  56                 if (peer->persistent_keepalive_interval)
  57                         wg_packet_send_keepalive(peer);
  58         }
  59 out:
  60         mutex_unlock(&wg->device_update_lock);
  61         return ret;
  62 }
  63
  64 static int wg_pm_notification(struct notifier_block *nb, unsigned long action, void *data)
  65 {
  66         struct wg_device *wg;
  67         struct wg_peer *peer;
  68
  69         /* If the machine is constantly suspending and resuming, as part of
  70          * its normal operation rather than as a somewhat rare event, then we
  71          * don't actually want to clear keys.
  72          */
  73         if (IS_ENABLED(CONFIG_PM_AUTOSLEEP) ||
  74             IS_ENABLED(CONFIG_PM_USERSPACE_AUTOSLEEP))
  75                 return 0;
  76
  77         if (action != PM_HIBERNATION_PREPARE && action != PM_SUSPEND_PREPARE)
  78                 return 0;
  79
  80         rtnl_lock();
  81         list_for_each_entry(wg, &device_list, device_list) {
  82                 mutex_lock(&wg->device_update_lock);
  83                 list_for_each_entry(peer, &wg->peer_list, peer_list) {
  84                         del_timer(&peer->timer_zero_key_material);
  85                         wg_noise_handshake_clear(&peer->handshake);
  86                         wg_noise_keypairs_clear(&peer->keypairs);
  87                 }
  88                 mutex_unlock(&wg->device_update_lock);
  89         }
  90         rtnl_unlock();
  91         rcu_barrier();
  92         return 0;
  93 }
  94
  95 static struct notifier_block pm_notifier = { .notifier_call = wg_pm_notification };
  96
  97 static int wg_vm_notification(struct notifier_block *nb, unsigned long action, void *data)
  98 {
  99         struct wg_device *wg;
 100         struct wg_peer *peer;
 101
 102         rtnl_lock();
 103         list_for_each_entry(wg, &device_list, device_list) {
 104                 mutex_lock(&wg->device_update_lock);
 105                 list_for_each_entry(peer, &wg->peer_list, peer_list)
 106                         wg_noise_expire_current_peer_keypairs(peer);
 107                 mutex_unlock(&wg->device_update_lock);
 108         }
 109         rtnl_unlock();
 110         return 0;
 111 }
 112
 113 static struct notifier_block vm_notifier = { .notifier_call = wg_vm_notification };
 114
 115 static int wg_stop(struct net_device *dev)
 116 {
 117         struct wg_device *wg = netdev_priv(dev);
 118         struct wg_peer *peer;
 119         struct sk_buff *skb;
 120
 121         mutex_lock(&wg->device_update_lock);
 122         list_for_each_entry(peer, &wg->peer_list, peer_list) {
 123                 wg_packet_purge_staged_packets(peer);
 124                 wg_timers_stop(peer);
 125                 wg_noise_handshake_clear(&peer->handshake);
 126                 wg_noise_keypairs_clear(&peer->keypairs);
 127                 wg_noise_reset_last_sent_handshake(&peer->last_sent_handshake);
 128         }
 129         mutex_unlock(&wg->device_update_lock);
 130         while ((skb = ptr_ring_consume(&wg->handshake_queue.ring)) != NULL)
 131                 kfree_skb(skb);
 132         atomic_set(&wg->handshake_queue_len, 0);
 133         wg_socket_reinit(wg, NULL, NULL);
 134         return 0;
 135 }
 136
 137 static netdev_tx_t wg_xmit(struct sk_buff *skb, struct net_device *dev)
 138 {
 139         struct wg_device *wg = netdev_priv(dev);
 140         struct sk_buff_head packets;
 141         struct wg_peer *peer;
 142         struct sk_buff *next;
 143         sa_family_t family;
 144         u32 mtu;
 145         int ret;
 146
 147         if (unlikely(!wg_check_packet_protocol(skb))) {
 148                 ret = -EPROTONOSUPPORT;
 149                 net_dbg_ratelimited("%s: Invalid IP packet\n", dev->name);
 150                 goto err;
 151         }
 152
 153         peer = wg_allowedips_lookup_dst(&wg->peer_allowedips, skb);
 154         if (unlikely(!peer)) {
 155                 ret = -ENOKEY;
 156                 if (skb->protocol == htons(ETH_P_IP))
 157                         net_dbg_ratelimited("%s: No peer has allowed IPs matching %pI4\n",
 158                                             dev->name, &ip_hdr(skb)->daddr);
 159                 else if (skb->protocol == htons(ETH_P_IPV6))
 160                         net_dbg_ratelimited("%s: No peer has allowed IPs matching %pI6\n",
 161                                             dev->name, &ipv6_hdr(skb)->daddr);
 162                 goto err_icmp;
 163         }
 164
 165         family = READ_ONCE(peer->endpoint.addr.sa_family);
 166         if (unlikely(family != AF_INET && family != AF_INET6)) {
 167                 ret = -EDESTADDRREQ;
 168                 net_dbg_ratelimited("%s: No valid endpoint has been configured or discovered for peer %llu\n",
 169                                     dev->name, peer->internal_id);
 170                 goto err_peer;
 171         }
 172
 173         mtu = skb_valid_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
 174
 175         __skb_queue_head_init(&packets);
 176         if (!skb_is_gso(skb)) {
 177                 skb_mark_not_on_list(skb);
 178         } else {
 179                 struct sk_buff *segs = skb_gso_segment(skb, 0);
 180
 181                 if (IS_ERR(segs)) {
 182                         ret = PTR_ERR(segs);
 183                         goto err_peer;
 184                 }
 185                 dev_kfree_skb(skb);
 186                 skb = segs;
 187         }
 188
 189         skb_list_walk_safe(skb, skb, next) {
 190                 skb_mark_not_on_list(skb);
 191
 192                 skb = skb_share_check(skb, GFP_ATOMIC);
 193                 if (unlikely(!skb))
 194                         continue;
 195
 196                 /* We only need to keep the original dst around for icmp,
 197                  * so at this point we're in a position to drop it.
 198                  */
 199                 skb_dst_drop(skb);
 200
 201                 PACKET_CB(skb)->mtu = mtu;
 202
 203                 __skb_queue_tail(&packets, skb);
 204         }
 205
 206         spin_lock_bh(&peer->staged_packet_queue.lock);
 207         /* If the queue is getting too big, we start removing the oldest packets
 208          * until it's small again. We do this before adding the new packet, so
 209          * we don't remove GSO segments that are in excess.
 210          */
 211         while (skb_queue_len(&peer->staged_packet_queue) > MAX_STAGED_PACKETS) {
 212                 dev_kfree_skb(__skb_dequeue(&peer->staged_packet_queue));
 213                 DEV_STATS_INC(dev, tx_dropped);
 214         }
 215         skb_queue_splice_tail(&packets, &peer->staged_packet_queue);
 216         spin_unlock_bh(&peer->staged_packet_queue.lock);
 217
 218         wg_packet_send_staged_packets(peer);
 219
 220         wg_peer_put(peer);
 221         return NETDEV_TX_OK;
 222
 223 err_peer:
 224         wg_peer_put(peer);
 225 err_icmp:
 226         if (skb->protocol == htons(ETH_P_IP))
 227                 icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
 228         else if (skb->protocol == htons(ETH_P_IPV6))
 229                 icmpv6_ndo_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0);
 230 err:
 231         DEV_STATS_INC(dev, tx_errors);
 232         kfree_skb(skb);
 233         return ret;
 234 }
 235
 236 static const struct net_device_ops netdev_ops = {
 237         .ndo_open               = wg_open,
 238         .ndo_stop               = wg_stop,
 239         .ndo_start_xmit         = wg_xmit,
 240         .ndo_get_stats64        = dev_get_tstats64
 241 };
 242
 243 static void wg_destruct(struct net_device *dev)
 244 {
 245         struct wg_device *wg = netdev_priv(dev);
 246
 247         rtnl_lock();
 248         list_del(&wg->device_list);
 249         rtnl_unlock();
 250         mutex_lock(&wg->device_update_lock);
 251         rcu_assign_pointer(wg->creating_net, NULL);
 252         wg->incoming_port = 0;
 253         wg_socket_reinit(wg, NULL, NULL);
 254         /* The final references are cleared in the below calls to destroy_workqueue. */
 255         wg_peer_remove_all(wg);
 256         destroy_workqueue(wg->handshake_receive_wq);
 257         destroy_workqueue(wg->handshake_send_wq);
 258         destroy_workqueue(wg->packet_crypt_wq);
 259         wg_packet_queue_free(&wg->handshake_queue, true);
 260         wg_packet_queue_free(&wg->decrypt_queue, false);
 261         wg_packet_queue_free(&wg->encrypt_queue, false);
 262         rcu_barrier(); /* Wait for all the peers to be actually freed. */
 263         wg_ratelimiter_uninit();
 264         memzero_explicit(&wg->static_identity, sizeof(wg->static_identity));
 265         free_percpu(dev->tstats);
 266         kvfree(wg->index_hashtable);
 267         kvfree(wg->peer_hashtable);
 268         mutex_unlock(&wg->device_update_lock);
 269
 270         pr_debug("%s: Interface destroyed\n", dev->name);
 271         free_netdev(dev);
 272 }
 273
 274 static const struct device_type device_type = { .name = KBUILD_MODNAME };
 275
 276 static void wg_setup(struct net_device *dev)
 277 {
 278         struct wg_device *wg = netdev_priv(dev);
 279         enum { WG_NETDEV_FEATURES = NETIF_F_HW_CSUM | NETIF_F_RXCSUM |
 280                                     NETIF_F_SG | NETIF_F_GSO |
 281                                     NETIF_F_GSO_SOFTWARE | NETIF_F_HIGHDMA };
 282         const int overhead = MESSAGE_MINIMUM_LENGTH + sizeof(struct udphdr) +
 283                              max(sizeof(struct ipv6hdr), sizeof(struct iphdr));
 284
 285         dev->netdev_ops = &netdev_ops;
 286         dev->header_ops = &ip_tunnel_header_ops;
 287         dev->hard_header_len = 0;
 288         dev->addr_len = 0;
 289         dev->needed_headroom = DATA_PACKET_HEAD_ROOM;
 290         dev->needed_tailroom = noise_encrypted_len(MESSAGE_PADDING_MULTIPLE);
 291         dev->type = ARPHRD_NONE;
 292         dev->flags = IFF_POINTOPOINT | IFF_NOARP;
 293         dev->priv_flags |= IFF_NO_QUEUE;
 294         dev->features |= NETIF_F_LLTX;
 295         dev->features |= WG_NETDEV_FEATURES;
 296         dev->hw_features |= WG_NETDEV_FEATURES;
 297         dev->hw_enc_features |= WG_NETDEV_FEATURES;
 298         dev->mtu = ETH_DATA_LEN - overhead;
 299         dev->max_mtu = round_down(INT_MAX, MESSAGE_PADDING_MULTIPLE) - overhead;
 300
 301         SET_NETDEV_DEVTYPE(dev, &device_type);
 302
 303         /* We need to keep the dst around in case of icmp replies. */
 304         netif_keep_dst(dev);
 305
 306         memset(wg, 0, sizeof(*wg));
 307         wg->dev = dev;
 308 }
 309
 310 static int wg_newlink(struct net *src_net, struct net_device *dev,
 311                       struct nlattr *tb[], struct nlattr *data[],
 312                       struct netlink_ext_ack *extack)
 313 {
 314         struct wg_device *wg = netdev_priv(dev);
 315         int ret = -ENOMEM;
 316
 317         rcu_assign_pointer(wg->creating_net, src_net);
 318         init_rwsem(&wg->static_identity.lock);
 319         mutex_init(&wg->socket_update_lock);
 320         mutex_init(&wg->device_update_lock);
 321         wg_allowedips_init(&wg->peer_allowedips);
 322         wg_cookie_checker_init(&wg->cookie_checker, wg);
 323         INIT_LIST_HEAD(&wg->peer_list);
 324         wg->device_update_gen = 1;
 325
 326         wg->peer_hashtable = wg_pubkey_hashtable_alloc();
 327         if (!wg->peer_hashtable)
 328                 return ret;
 329
 330         wg->index_hashtable = wg_index_hashtable_alloc();
 331         if (!wg->index_hashtable)
 332                 goto err_free_peer_hashtable;
 333
 334         dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
 335         if (!dev->tstats)
 336                 goto err_free_index_hashtable;
 337
 338         wg->handshake_receive_wq = alloc_workqueue("wg-kex-%s",
 339                         WQ_CPU_INTENSIVE | WQ_FREEZABLE, 0, dev->name);
 340         if (!wg->handshake_receive_wq)
 341                 goto err_free_tstats;
 342
 343         wg->handshake_send_wq = alloc_workqueue("wg-kex-%s",
 344                         WQ_UNBOUND | WQ_FREEZABLE, 0, dev->name);
 345         if (!wg->handshake_send_wq)
 346                 goto err_destroy_handshake_receive;
 347
 348         wg->packet_crypt_wq = alloc_workqueue("wg-crypt-%s",
 349                         WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM, 0, dev->name);
 350         if (!wg->packet_crypt_wq)
 351                 goto err_destroy_handshake_send;
 352
 353         ret = wg_packet_queue_init(&wg->encrypt_queue, wg_packet_encrypt_worker,
 354                                    MAX_QUEUED_PACKETS);
 355         if (ret < 0)
 356                 goto err_destroy_packet_crypt;
 357
 358         ret = wg_packet_queue_init(&wg->decrypt_queue, wg_packet_decrypt_worker,
 359                                    MAX_QUEUED_PACKETS);
 360         if (ret < 0)
 361                 goto err_free_encrypt_queue;
 362
 363         ret = wg_packet_queue_init(&wg->handshake_queue, wg_packet_handshake_receive_worker,
 364                                    MAX_QUEUED_INCOMING_HANDSHAKES);
 365         if (ret < 0)
 366                 goto err_free_decrypt_queue;
 367
 368         ret = wg_ratelimiter_init();
 369         if (ret < 0)
 370                 goto err_free_handshake_queue;
 371
 372         ret = register_netdevice(dev);
 373         if (ret < 0)
 374                 goto err_uninit_ratelimiter;
 375
 376         list_add(&wg->device_list, &device_list);
 377
 378         /* We wait until the end to assign priv_destructor, so that
 379          * register_netdevice doesn't call it for us if it fails.
 380          */
 381         dev->priv_destructor = wg_destruct;
 382
 383         pr_debug("%s: Interface created\n", dev->name);
 384         return ret;
 385
 386 err_uninit_ratelimiter:
 387         wg_ratelimiter_uninit();
 388 err_free_handshake_queue:
 389         wg_packet_queue_free(&wg->handshake_queue, false);
 390 err_free_decrypt_queue:
 391         wg_packet_queue_free(&wg->decrypt_queue, false);
 392 err_free_encrypt_queue:
 393         wg_packet_queue_free(&wg->encrypt_queue, false);
 394 err_destroy_packet_crypt:
 395         destroy_workqueue(wg->packet_crypt_wq);
 396 err_destroy_handshake_send:
 397         destroy_workqueue(wg->handshake_send_wq);
 398 err_destroy_handshake_receive:
 399         destroy_workqueue(wg->handshake_receive_wq);
 400 err_free_tstats:
 401         free_percpu(dev->tstats);
 402 err_free_index_hashtable:
 403         kvfree(wg->index_hashtable);
 404 err_free_peer_hashtable:
 405         kvfree(wg->peer_hashtable);
 406         return ret;
 407 }
 408
 409 static struct rtnl_link_ops link_ops __read_mostly = {
 410         .kind                   = KBUILD_MODNAME,
 411         .priv_size              = sizeof(struct wg_device),
 412         .setup                  = wg_setup,
 413         .newlink                = wg_newlink,
 414 };
 415
 416 static void wg_netns_pre_exit(struct net *net)
 417 {
 418         struct wg_device *wg;
 419         struct wg_peer *peer;
 420
 421         rtnl_lock();
 422         list_for_each_entry(wg, &device_list, device_list) {
 423                 if (rcu_access_pointer(wg->creating_net) == net) {
 424                         pr_debug("%s: Creating namespace exiting\n", wg->dev->name);
 425                         netif_carrier_off(wg->dev);
 426                         mutex_lock(&wg->device_update_lock);
 427                         rcu_assign_pointer(wg->creating_net, NULL);
 428                         wg_socket_reinit(wg, NULL, NULL);
 429                         list_for_each_entry(peer, &wg->peer_list, peer_list)
 430                                 wg_socket_clear_peer_endpoint_src(peer);
 431                         mutex_unlock(&wg->device_update_lock);
 432                 }
 433         }
 434         rtnl_unlock();
 435 }
 436
 437 static struct pernet_operations pernet_ops = {
 438         .pre_exit = wg_netns_pre_exit
 439 };
 440
 441 int __init wg_device_init(void)
 442 {
 443         int ret;
 444
 445         ret = register_pm_notifier(&pm_notifier);
 446         if (ret)
 447                 return ret;
 448
 449         ret = register_random_vmfork_notifier(&vm_notifier);
 450         if (ret)
 451                 goto error_pm;
 452
 453         ret = register_pernet_device(&pernet_ops);
 454         if (ret)
 455                 goto error_vm;
 456
 457         ret = rtnl_link_register(&link_ops);
 458         if (ret)
 459                 goto error_pernet;
 460
 461         return 0;
 462
 463 error_pernet:
 464         unregister_pernet_device(&pernet_ops);
 465 error_vm:
 466         unregister_random_vmfork_notifier(&vm_notifier);
 467 error_pm:
 468         unregister_pm_notifier(&pm_notifier);
 469         return ret;
 470 }
 471
 472 void wg_device_uninit(void)
 473 {
 474         rtnl_link_unregister(&link_ops);
 475         unregister_pernet_device(&pernet_ops);
 476         unregister_random_vmfork_notifier(&vm_notifier);
 477         unregister_pm_notifier(&pm_notifier);
 478         rcu_barrier();
 479 }