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