net/l2tp/l2tp_core.c

   1 /*
   2  * L2TP core.
   3  *
   4  * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
   5  *
   6  * This file contains some code of the original L2TPv2 pppol2tp
   7  * driver, which has the following copyright:
   8  *
   9  * Authors:     Martijn van Oosterhout <kleptog@svana.org>
  10  *              James Chapman (jchapman@katalix.com)
  11  * Contributors:
  12  *              Michal Ostrowski <mostrows@speakeasy.net>
  13  *              Arnaldo Carvalho de Melo <acme@xconectiva.com.br>
  14  *              David S. Miller (davem@redhat.com)
  15  *
  16  * This program is free software; you can redistribute it and/or modify
  17  * it under the terms of the GNU General Public License version 2 as
  18  * published by the Free Software Foundation.
  19  */
  20
  21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  22
  23 #include <linux/module.h>
  24 #include <linux/string.h>
  25 #include <linux/list.h>
  26 #include <linux/rculist.h>
  27 #include <linux/uaccess.h>
  28
  29 #include <linux/kernel.h>
  30 #include <linux/spinlock.h>
  31 #include <linux/kthread.h>
  32 #include <linux/sched.h>
  33 #include <linux/slab.h>
  34 #include <linux/errno.h>
  35 #include <linux/jiffies.h>
  36
  37 #include <linux/netdevice.h>
  38 #include <linux/net.h>
  39 #include <linux/inetdevice.h>
  40 #include <linux/skbuff.h>
  41 #include <linux/init.h>
  42 #include <linux/in.h>
  43 #include <linux/ip.h>
  44 #include <linux/udp.h>
  45 #include <linux/l2tp.h>
  46 #include <linux/hash.h>
  47 #include <linux/sort.h>
  48 #include <linux/file.h>
  49 #include <linux/nsproxy.h>
  50 #include <net/net_namespace.h>
  51 #include <net/netns/generic.h>
  52 #include <net/dst.h>
  53 #include <net/ip.h>
  54 #include <net/udp.h>
  55 #include <net/udp_tunnel.h>
  56 #include <net/inet_common.h>
  57 #include <net/xfrm.h>
  58 #include <net/protocol.h>
  59 #include <net/inet6_connection_sock.h>
  60 #include <net/inet_ecn.h>
  61 #include <net/ip6_route.h>
  62 #include <net/ip6_checksum.h>
  63
  64 #include <asm/byteorder.h>
  65 #include <linux/atomic.h>
  66
  67 #include "l2tp_core.h"
  68
  69 #define L2TP_DRV_VERSION        "V2.0"
  70
  71 /* L2TP header constants */
  72 #define L2TP_HDRFLAG_T     0x8000
  73 #define L2TP_HDRFLAG_L     0x4000
  74 #define L2TP_HDRFLAG_S     0x0800
  75 #define L2TP_HDRFLAG_O     0x0200
  76 #define L2TP_HDRFLAG_P     0x0100
  77
  78 #define L2TP_HDR_VER_MASK  0x000F
  79 #define L2TP_HDR_VER_2     0x0002
  80 #define L2TP_HDR_VER_3     0x0003
  81
  82 /* L2TPv3 default L2-specific sublayer */
  83 #define L2TP_SLFLAG_S      0x40000000
  84 #define L2TP_SL_SEQ_MASK   0x00ffffff
  85
  86 #define L2TP_HDR_SIZE_SEQ               10
  87 #define L2TP_HDR_SIZE_NOSEQ             6
  88
  89 /* Default trace flags */
  90 #define L2TP_DEFAULT_DEBUG_FLAGS        0
  91
  92 /* Private data stored for received packets in the skb.
  93  */
  94 struct l2tp_skb_cb {
  95         u32                     ns;
  96         u16                     has_seq;
  97         u16                     length;
  98         unsigned long           expires;
  99 };
 100
 101 #define L2TP_SKB_CB(skb)        ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
 102
 103 static atomic_t l2tp_tunnel_count;
 104 static atomic_t l2tp_session_count;
 105 static struct workqueue_struct *l2tp_wq;
 106
 107 /* per-net private data for this module */
 108 static unsigned int l2tp_net_id;
 109 struct l2tp_net {
 110         struct list_head l2tp_tunnel_list;
 111         spinlock_t l2tp_tunnel_list_lock;
 112         struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
 113         spinlock_t l2tp_session_hlist_lock;
 114 };
 115
 116
 117 static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk)
 118 {
 119         return sk->sk_user_data;
 120 }
 121
 122 static inline struct l2tp_net *l2tp_pernet(const struct net *net)
 123 {
 124         BUG_ON(!net);
 125
 126         return net_generic(net, l2tp_net_id);
 127 }
 128
 129 /* Session hash global list for L2TPv3.
 130  * The session_id SHOULD be random according to RFC3931, but several
 131  * L2TP implementations use incrementing session_ids.  So we do a real
 132  * hash on the session_id, rather than a simple bitmask.
 133  */
 134 static inline struct hlist_head *
 135 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
 136 {
 137         return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
 138
 139 }
 140
 141 /* Lookup the tunnel socket, possibly involving the fs code if the socket is
 142  * owned by userspace.  A struct sock returned from this function must be
 143  * released using l2tp_tunnel_sock_put once you're done with it.
 144  */
 145 static struct sock *l2tp_tunnel_sock_lookup(struct l2tp_tunnel *tunnel)
 146 {
 147         int err = 0;
 148         struct socket *sock = NULL;
 149         struct sock *sk = NULL;
 150
 151         if (!tunnel)
 152                 goto out;
 153
 154         if (tunnel->fd >= 0) {
 155                 /* Socket is owned by userspace, who might be in the process
 156                  * of closing it.  Look the socket up using the fd to ensure
 157                  * consistency.
 158                  */
 159                 sock = sockfd_lookup(tunnel->fd, &err);
 160                 if (sock)
 161                         sk = sock->sk;
 162         } else {
 163                 /* Socket is owned by kernelspace */
 164                 sk = tunnel->sock;
 165                 sock_hold(sk);
 166         }
 167
 168 out:
 169         return sk;
 170 }
 171
 172 /* Drop a reference to a tunnel socket obtained via. l2tp_tunnel_sock_put */
 173 static void l2tp_tunnel_sock_put(struct sock *sk)
 174 {
 175         struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
 176         if (tunnel) {
 177                 if (tunnel->fd >= 0) {
 178                         /* Socket is owned by userspace */
 179                         sockfd_put(sk->sk_socket);
 180                 }
 181                 sock_put(sk);
 182         }
 183         sock_put(sk);
 184 }
 185
 186 /* Session hash list.
 187  * The session_id SHOULD be random according to RFC2661, but several
 188  * L2TP implementations (Cisco and Microsoft) use incrementing
 189  * session_ids.  So we do a real hash on the session_id, rather than a
 190  * simple bitmask.
 191  */
 192 static inline struct hlist_head *
 193 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
 194 {
 195         return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
 196 }
 197
 198 /* Lookup a tunnel. A new reference is held on the returned tunnel. */
 199 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id)
 200 {
 201         const struct l2tp_net *pn = l2tp_pernet(net);
 202         struct l2tp_tunnel *tunnel;
 203
 204         rcu_read_lock_bh();
 205         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 206                 if (tunnel->tunnel_id == tunnel_id) {
 207                         l2tp_tunnel_inc_refcount(tunnel);
 208                         rcu_read_unlock_bh();
 209
 210                         return tunnel;
 211                 }
 212         }
 213         rcu_read_unlock_bh();
 214
 215         return NULL;
 216 }
 217 EXPORT_SYMBOL_GPL(l2tp_tunnel_get);
 218
 219 /* Lookup a session. A new reference is held on the returned session.
 220  * Optionally calls session->ref() too if do_ref is true.
 221  */
 222 struct l2tp_session *l2tp_session_get(const struct net *net,
 223                                       struct l2tp_tunnel *tunnel,
 224                                       u32 session_id, bool do_ref)
 225 {
 226         struct hlist_head *session_list;
 227         struct l2tp_session *session;
 228
 229         if (!tunnel) {
 230                 struct l2tp_net *pn = l2tp_pernet(net);
 231
 232                 session_list = l2tp_session_id_hash_2(pn, session_id);
 233
 234                 rcu_read_lock_bh();
 235                 hlist_for_each_entry_rcu(session, session_list, global_hlist) {
 236                         if (session->session_id == session_id) {
 237                                 l2tp_session_inc_refcount(session);
 238                                 if (do_ref && session->ref)
 239                                         session->ref(session);
 240                                 rcu_read_unlock_bh();
 241
 242                                 return session;
 243                         }
 244                 }
 245                 rcu_read_unlock_bh();
 246
 247                 return NULL;
 248         }
 249
 250         session_list = l2tp_session_id_hash(tunnel, session_id);
 251         read_lock_bh(&tunnel->hlist_lock);
 252         hlist_for_each_entry(session, session_list, hlist) {
 253                 if (session->session_id == session_id) {
 254                         l2tp_session_inc_refcount(session);
 255                         if (do_ref && session->ref)
 256                                 session->ref(session);
 257                         read_unlock_bh(&tunnel->hlist_lock);
 258
 259                         return session;
 260                 }
 261         }
 262         read_unlock_bh(&tunnel->hlist_lock);
 263
 264         return NULL;
 265 }
 266 EXPORT_SYMBOL_GPL(l2tp_session_get);
 267
 268 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth,
 269                                           bool do_ref)
 270 {
 271         int hash;
 272         struct l2tp_session *session;
 273         int count = 0;
 274
 275         read_lock_bh(&tunnel->hlist_lock);
 276         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
 277                 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) {
 278                         if (++count > nth) {
 279                                 l2tp_session_inc_refcount(session);
 280                                 if (do_ref && session->ref)
 281                                         session->ref(session);
 282                                 read_unlock_bh(&tunnel->hlist_lock);
 283                                 return session;
 284                         }
 285                 }
 286         }
 287
 288         read_unlock_bh(&tunnel->hlist_lock);
 289
 290         return NULL;
 291 }
 292 EXPORT_SYMBOL_GPL(l2tp_session_get_nth);
 293
 294 /* Lookup a session by interface name.
 295  * This is very inefficient but is only used by management interfaces.
 296  */
 297 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 298                                                 const char *ifname,
 299                                                 bool do_ref)
 300 {
 301         struct l2tp_net *pn = l2tp_pernet(net);
 302         int hash;
 303         struct l2tp_session *session;
 304
 305         rcu_read_lock_bh();
 306         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
 307                 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) {
 308                         if (!strcmp(session->ifname, ifname)) {
 309                                 l2tp_session_inc_refcount(session);
 310                                 if (do_ref && session->ref)
 311                                         session->ref(session);
 312                                 rcu_read_unlock_bh();
 313
 314                                 return session;
 315                         }
 316                 }
 317         }
 318
 319         rcu_read_unlock_bh();
 320
 321         return NULL;
 322 }
 323 EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname);
 324
 325 static int l2tp_session_add_to_tunnel(struct l2tp_tunnel *tunnel,
 326                                       struct l2tp_session *session)
 327 {
 328         struct l2tp_session *session_walk;
 329         struct hlist_head *g_head;
 330         struct hlist_head *head;
 331         struct l2tp_net *pn;
 332
 333         head = l2tp_session_id_hash(tunnel, session->session_id);
 334
 335         write_lock_bh(&tunnel->hlist_lock);
 336         hlist_for_each_entry(session_walk, head, hlist)
 337                 if (session_walk->session_id == session->session_id)
 338                         goto exist;
 339
 340         if (tunnel->version == L2TP_HDR_VER_3) {
 341                 pn = l2tp_pernet(tunnel->l2tp_net);
 342                 g_head = l2tp_session_id_hash_2(l2tp_pernet(tunnel->l2tp_net),
 343                                                 session->session_id);
 344
 345                 spin_lock_bh(&pn->l2tp_session_hlist_lock);
 346                 hlist_for_each_entry(session_walk, g_head, global_hlist)
 347                         if (session_walk->session_id == session->session_id)
 348                                 goto exist_glob;
 349
 350                 hlist_add_head_rcu(&session->global_hlist, g_head);
 351                 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
 352         }
 353
 354         hlist_add_head(&session->hlist, head);
 355         write_unlock_bh(&tunnel->hlist_lock);
 356
 357         return 0;
 358
 359 exist_glob:
 360         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
 361 exist:
 362         write_unlock_bh(&tunnel->hlist_lock);
 363
 364         return -EEXIST;
 365 }
 366
 367 /* Lookup a tunnel by id
 368  */
 369 struct l2tp_tunnel *l2tp_tunnel_find(const struct net *net, u32 tunnel_id)
 370 {
 371         struct l2tp_tunnel *tunnel;
 372         struct l2tp_net *pn = l2tp_pernet(net);
 373
 374         rcu_read_lock_bh();
 375         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 376                 if (tunnel->tunnel_id == tunnel_id) {
 377                         rcu_read_unlock_bh();
 378                         return tunnel;
 379                 }
 380         }
 381         rcu_read_unlock_bh();
 382
 383         return NULL;
 384 }
 385 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
 386
 387 struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth)
 388 {
 389         struct l2tp_net *pn = l2tp_pernet(net);
 390         struct l2tp_tunnel *tunnel;
 391         int count = 0;
 392
 393         rcu_read_lock_bh();
 394         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 395                 if (++count > nth) {
 396                         rcu_read_unlock_bh();
 397                         return tunnel;
 398                 }
 399         }
 400
 401         rcu_read_unlock_bh();
 402
 403         return NULL;
 404 }
 405 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
 406
 407 /*****************************************************************************
 408  * Receive data handling
 409  *****************************************************************************/
 410
 411 /* Queue a skb in order. We come here only if the skb has an L2TP sequence
 412  * number.
 413  */
 414 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
 415 {
 416         struct sk_buff *skbp;
 417         struct sk_buff *tmp;
 418         u32 ns = L2TP_SKB_CB(skb)->ns;
 419
 420         spin_lock_bh(&session->reorder_q.lock);
 421         skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
 422                 if (L2TP_SKB_CB(skbp)->ns > ns) {
 423                         __skb_queue_before(&session->reorder_q, skbp, skb);
 424                         l2tp_dbg(session, L2TP_MSG_SEQ,
 425                                  "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
 426                                  session->name, ns, L2TP_SKB_CB(skbp)->ns,
 427                                  skb_queue_len(&session->reorder_q));
 428                         atomic_long_inc(&session->stats.rx_oos_packets);
 429                         goto out;
 430                 }
 431         }
 432
 433         __skb_queue_tail(&session->reorder_q, skb);
 434
 435 out:
 436         spin_unlock_bh(&session->reorder_q.lock);
 437 }
 438
 439 /* Dequeue a single skb.
 440  */
 441 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
 442 {
 443         struct l2tp_tunnel *tunnel = session->tunnel;
 444         int length = L2TP_SKB_CB(skb)->length;
 445
 446         /* We're about to requeue the skb, so return resources
 447          * to its current owner (a socket receive buffer).
 448          */
 449         skb_orphan(skb);
 450
 451         atomic_long_inc(&tunnel->stats.rx_packets);
 452         atomic_long_add(length, &tunnel->stats.rx_bytes);
 453         atomic_long_inc(&session->stats.rx_packets);
 454         atomic_long_add(length, &session->stats.rx_bytes);
 455
 456         if (L2TP_SKB_CB(skb)->has_seq) {
 457                 /* Bump our Nr */
 458                 session->nr++;
 459                 session->nr &= session->nr_max;
 460
 461                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
 462                          session->name, session->nr);
 463         }
 464
 465         /* call private receive handler */
 466         if (session->recv_skb != NULL)
 467                 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
 468         else
 469                 kfree_skb(skb);
 470
 471         if (session->deref)
 472                 (*session->deref)(session);
 473 }
 474
 475 /* Dequeue skbs from the session's reorder_q, subject to packet order.
 476  * Skbs that have been in the queue for too long are simply discarded.
 477  */
 478 static void l2tp_recv_dequeue(struct l2tp_session *session)
 479 {
 480         struct sk_buff *skb;
 481         struct sk_buff *tmp;
 482
 483         /* If the pkt at the head of the queue has the nr that we
 484          * expect to send up next, dequeue it and any other
 485          * in-sequence packets behind it.
 486          */
 487 start:
 488         spin_lock_bh(&session->reorder_q.lock);
 489         skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
 490                 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
 491                         atomic_long_inc(&session->stats.rx_seq_discards);
 492                         atomic_long_inc(&session->stats.rx_errors);
 493                         l2tp_dbg(session, L2TP_MSG_SEQ,
 494                                  "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
 495                                  session->name, L2TP_SKB_CB(skb)->ns,
 496                                  L2TP_SKB_CB(skb)->length, session->nr,
 497                                  skb_queue_len(&session->reorder_q));
 498                         session->reorder_skip = 1;
 499                         __skb_unlink(skb, &session->reorder_q);
 500                         kfree_skb(skb);
 501                         if (session->deref)
 502                                 (*session->deref)(session);
 503                         continue;
 504                 }
 505
 506                 if (L2TP_SKB_CB(skb)->has_seq) {
 507                         if (session->reorder_skip) {
 508                                 l2tp_dbg(session, L2TP_MSG_SEQ,
 509                                          "%s: advancing nr to next pkt: %u -> %u",
 510                                          session->name, session->nr,
 511                                          L2TP_SKB_CB(skb)->ns);
 512                                 session->reorder_skip = 0;
 513                                 session->nr = L2TP_SKB_CB(skb)->ns;
 514                         }
 515                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
 516                                 l2tp_dbg(session, L2TP_MSG_SEQ,
 517                                          "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
 518                                          session->name, L2TP_SKB_CB(skb)->ns,
 519                                          L2TP_SKB_CB(skb)->length, session->nr,
 520                                          skb_queue_len(&session->reorder_q));
 521                                 goto out;
 522                         }
 523                 }
 524                 __skb_unlink(skb, &session->reorder_q);
 525
 526                 /* Process the skb. We release the queue lock while we
 527                  * do so to let other contexts process the queue.
 528                  */
 529                 spin_unlock_bh(&session->reorder_q.lock);
 530                 l2tp_recv_dequeue_skb(session, skb);
 531                 goto start;
 532         }
 533
 534 out:
 535         spin_unlock_bh(&session->reorder_q.lock);
 536 }
 537
 538 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr)
 539 {
 540         u32 nws;
 541
 542         if (nr >= session->nr)
 543                 nws = nr - session->nr;
 544         else
 545                 nws = (session->nr_max + 1) - (session->nr - nr);
 546
 547         return nws < session->nr_window_size;
 548 }
 549
 550 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if
 551  * acceptable, else non-zero.
 552  */
 553 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
 554 {
 555         if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) {
 556                 /* Packet sequence number is outside allowed window.
 557                  * Discard it.
 558                  */
 559                 l2tp_dbg(session, L2TP_MSG_SEQ,
 560                          "%s: pkt %u len %d discarded, outside window, nr=%u\n",
 561                          session->name, L2TP_SKB_CB(skb)->ns,
 562                          L2TP_SKB_CB(skb)->length, session->nr);
 563                 goto discard;
 564         }
 565
 566         if (session->reorder_timeout != 0) {
 567                 /* Packet reordering enabled. Add skb to session's
 568                  * reorder queue, in order of ns.
 569                  */
 570                 l2tp_recv_queue_skb(session, skb);
 571                 goto out;
 572         }
 573
 574         /* Packet reordering disabled. Discard out-of-sequence packets, while
 575          * tracking the number if in-sequence packets after the first OOS packet
 576          * is seen. After nr_oos_count_max in-sequence packets, reset the
 577          * sequence number to re-enable packet reception.
 578          */
 579         if (L2TP_SKB_CB(skb)->ns == session->nr) {
 580                 skb_queue_tail(&session->reorder_q, skb);
 581         } else {
 582                 u32 nr_oos = L2TP_SKB_CB(skb)->ns;
 583                 u32 nr_next = (session->nr_oos + 1) & session->nr_max;
 584
 585                 if (nr_oos == nr_next)
 586                         session->nr_oos_count++;
 587                 else
 588                         session->nr_oos_count = 0;
 589
 590                 session->nr_oos = nr_oos;
 591                 if (session->nr_oos_count > session->nr_oos_count_max) {
 592                         session->reorder_skip = 1;
 593                         l2tp_dbg(session, L2TP_MSG_SEQ,
 594                                  "%s: %d oos packets received. Resetting sequence numbers\n",
 595                                  session->name, session->nr_oos_count);
 596                 }
 597                 if (!session->reorder_skip) {
 598                         atomic_long_inc(&session->stats.rx_seq_discards);
 599                         l2tp_dbg(session, L2TP_MSG_SEQ,
 600                                  "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
 601                                  session->name, L2TP_SKB_CB(skb)->ns,
 602                                  L2TP_SKB_CB(skb)->length, session->nr,
 603                                  skb_queue_len(&session->reorder_q));
 604                         goto discard;
 605                 }
 606                 skb_queue_tail(&session->reorder_q, skb);
 607         }
 608
 609 out:
 610         return 0;
 611
 612 discard:
 613         return 1;
 614 }
 615
 616 /* Do receive processing of L2TP data frames. We handle both L2TPv2
 617  * and L2TPv3 data frames here.
 618  *
 619  * L2TPv2 Data Message Header
 620  *
 621  *  0                   1                   2                   3
 622  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 623  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 624  * |T|L|x|x|S|x|O|P|x|x|x|x|  Ver  |          Length (opt)         |
 625  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 626  * |           Tunnel ID           |           Session ID          |
 627  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 628  * |             Ns (opt)          |             Nr (opt)          |
 629  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 630  * |      Offset Size (opt)        |    Offset pad... (opt)
 631  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 632  *
 633  * Data frames are marked by T=0. All other fields are the same as
 634  * those in L2TP control frames.
 635  *
 636  * L2TPv3 Data Message Header
 637  *
 638  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 639  * |                      L2TP Session Header                      |
 640  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 641  * |                      L2-Specific Sublayer                     |
 642  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 643  * |                        Tunnel Payload                      ...
 644  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 645  *
 646  * L2TPv3 Session Header Over IP
 647  *
 648  *  0                   1                   2                   3
 649  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 650  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 651  * |                           Session ID                          |
 652  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 653  * |               Cookie (optional, maximum 64 bits)...
 654  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 655  *                                                                 |
 656  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 657  *
 658  * L2TPv3 L2-Specific Sublayer Format
 659  *
 660  *  0                   1                   2                   3
 661  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 662  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 663  * |x|S|x|x|x|x|x|x|              Sequence Number                  |
 664  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 665  *
 666  * Cookie value, sublayer format and offset (pad) are negotiated with
 667  * the peer when the session is set up. Unlike L2TPv2, we do not need
 668  * to parse the packet header to determine if optional fields are
 669  * present.
 670  *
 671  * Caller must already have parsed the frame and determined that it is
 672  * a data (not control) frame before coming here. Fields up to the
 673  * session-id have already been parsed and ptr points to the data
 674  * after the session-id.
 675  *
 676  * session->ref() must have been called prior to l2tp_recv_common().
 677  * session->deref() will be called automatically after skb is processed.
 678  */
 679 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 680                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 681                       int length, int (*payload_hook)(struct sk_buff *skb))
 682 {
 683         struct l2tp_tunnel *tunnel = session->tunnel;
 684         int offset;
 685         u32 ns, nr;
 686
 687         /* Parse and check optional cookie */
 688         if (session->peer_cookie_len > 0) {
 689                 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
 690                         l2tp_info(tunnel, L2TP_MSG_DATA,
 691                                   "%s: cookie mismatch (%u/%u). Discarding.\n",
 692                                   tunnel->name, tunnel->tunnel_id,
 693                                   session->session_id);
 694                         atomic_long_inc(&session->stats.rx_cookie_discards);
 695                         goto discard;
 696                 }
 697                 ptr += session->peer_cookie_len;
 698         }
 699
 700         /* Handle the optional sequence numbers. Sequence numbers are
 701          * in different places for L2TPv2 and L2TPv3.
 702          *
 703          * If we are the LAC, enable/disable sequence numbers under
 704          * the control of the LNS.  If no sequence numbers present but
 705          * we were expecting them, discard frame.
 706          */
 707         ns = nr = 0;
 708         L2TP_SKB_CB(skb)->has_seq = 0;
 709         if (tunnel->version == L2TP_HDR_VER_2) {
 710                 if (hdrflags & L2TP_HDRFLAG_S) {
 711                         ns = ntohs(*(__be16 *) ptr);
 712                         ptr += 2;
 713                         nr = ntohs(*(__be16 *) ptr);
 714                         ptr += 2;
 715
 716                         /* Store L2TP info in the skb */
 717                         L2TP_SKB_CB(skb)->ns = ns;
 718                         L2TP_SKB_CB(skb)->has_seq = 1;
 719
 720                         l2tp_dbg(session, L2TP_MSG_SEQ,
 721                                  "%s: recv data ns=%u, nr=%u, session nr=%u\n",
 722                                  session->name, ns, nr, session->nr);
 723                 }
 724         } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
 725                 u32 l2h = ntohl(*(__be32 *) ptr);
 726
 727                 if (l2h & 0x40000000) {
 728                         ns = l2h & 0x00ffffff;
 729
 730                         /* Store L2TP info in the skb */
 731                         L2TP_SKB_CB(skb)->ns = ns;
 732                         L2TP_SKB_CB(skb)->has_seq = 1;
 733
 734                         l2tp_dbg(session, L2TP_MSG_SEQ,
 735                                  "%s: recv data ns=%u, session nr=%u\n",
 736                                  session->name, ns, session->nr);
 737                 }
 738         }
 739
 740         /* Advance past L2-specific header, if present */
 741         ptr += session->l2specific_len;
 742
 743         if (L2TP_SKB_CB(skb)->has_seq) {
 744                 /* Received a packet with sequence numbers. If we're the LNS,
 745                  * check if we sre sending sequence numbers and if not,
 746                  * configure it so.
 747                  */
 748                 if ((!session->lns_mode) && (!session->send_seq)) {
 749                         l2tp_info(session, L2TP_MSG_SEQ,
 750                                   "%s: requested to enable seq numbers by LNS\n",
 751                                   session->name);
 752                         session->send_seq = 1;
 753                         l2tp_session_set_header_len(session, tunnel->version);
 754                 }
 755         } else {
 756                 /* No sequence numbers.
 757                  * If user has configured mandatory sequence numbers, discard.
 758                  */
 759                 if (session->recv_seq) {
 760                         l2tp_warn(session, L2TP_MSG_SEQ,
 761                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 762                                   session->name);
 763                         atomic_long_inc(&session->stats.rx_seq_discards);
 764                         goto discard;
 765                 }
 766
 767                 /* If we're the LAC and we're sending sequence numbers, the
 768                  * LNS has requested that we no longer send sequence numbers.
 769                  * If we're the LNS and we're sending sequence numbers, the
 770                  * LAC is broken. Discard the frame.
 771                  */
 772                 if ((!session->lns_mode) && (session->send_seq)) {
 773                         l2tp_info(session, L2TP_MSG_SEQ,
 774                                   "%s: requested to disable seq numbers by LNS\n",
 775                                   session->name);
 776                         session->send_seq = 0;
 777                         l2tp_session_set_header_len(session, tunnel->version);
 778                 } else if (session->send_seq) {
 779                         l2tp_warn(session, L2TP_MSG_SEQ,
 780                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 781                                   session->name);
 782                         atomic_long_inc(&session->stats.rx_seq_discards);
 783                         goto discard;
 784                 }
 785         }
 786
 787         /* Session data offset is handled differently for L2TPv2 and
 788          * L2TPv3. For L2TPv2, there is an optional 16-bit value in
 789          * the header. For L2TPv3, the offset is negotiated using AVPs
 790          * in the session setup control protocol.
 791          */
 792         if (tunnel->version == L2TP_HDR_VER_2) {
 793                 /* If offset bit set, skip it. */
 794                 if (hdrflags & L2TP_HDRFLAG_O) {
 795                         offset = ntohs(*(__be16 *)ptr);
 796                         ptr += 2 + offset;
 797                 }
 798         } else
 799                 ptr += session->offset;
 800
 801         offset = ptr - optr;
 802         if (!pskb_may_pull(skb, offset))
 803                 goto discard;
 804
 805         __skb_pull(skb, offset);
 806
 807         /* If caller wants to process the payload before we queue the
 808          * packet, do so now.
 809          */
 810         if (payload_hook)
 811                 if ((*payload_hook)(skb))
 812                         goto discard;
 813
 814         /* Prepare skb for adding to the session's reorder_q.  Hold
 815          * packets for max reorder_timeout or 1 second if not
 816          * reordering.
 817          */
 818         L2TP_SKB_CB(skb)->length = length;
 819         L2TP_SKB_CB(skb)->expires = jiffies +
 820                 (session->reorder_timeout ? session->reorder_timeout : HZ);
 821
 822         /* Add packet to the session's receive queue. Reordering is done here, if
 823          * enabled. Saved L2TP protocol info is stored in skb->sb[].
 824          */
 825         if (L2TP_SKB_CB(skb)->has_seq) {
 826                 if (l2tp_recv_data_seq(session, skb))
 827                         goto discard;
 828         } else {
 829                 /* No sequence numbers. Add the skb to the tail of the
 830                  * reorder queue. This ensures that it will be
 831                  * delivered after all previous sequenced skbs.
 832                  */
 833                 skb_queue_tail(&session->reorder_q, skb);
 834         }
 835
 836         /* Try to dequeue as many skbs from reorder_q as we can. */
 837         l2tp_recv_dequeue(session);
 838
 839         return;
 840
 841 discard:
 842         atomic_long_inc(&session->stats.rx_errors);
 843         kfree_skb(skb);
 844
 845         if (session->deref)
 846                 (*session->deref)(session);
 847 }
 848 EXPORT_SYMBOL(l2tp_recv_common);
 849
 850 /* Drop skbs from the session's reorder_q
 851  */
 852 int l2tp_session_queue_purge(struct l2tp_session *session)
 853 {
 854         struct sk_buff *skb = NULL;
 855         BUG_ON(!session);
 856         BUG_ON(session->magic != L2TP_SESSION_MAGIC);
 857         while ((skb = skb_dequeue(&session->reorder_q))) {
 858                 atomic_long_inc(&session->stats.rx_errors);
 859                 kfree_skb(skb);
 860                 if (session->deref)
 861                         (*session->deref)(session);
 862         }
 863         return 0;
 864 }
 865 EXPORT_SYMBOL_GPL(l2tp_session_queue_purge);
 866
 867 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
 868  * here. The skb is not on a list when we get here.
 869  * Returns 0 if the packet was a data packet and was successfully passed on.
 870  * Returns 1 if the packet was not a good data packet and could not be
 871  * forwarded.  All such packets are passed up to userspace to deal with.
 872  */
 873 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
 874                               int (*payload_hook)(struct sk_buff *skb))
 875 {
 876         struct l2tp_session *session = NULL;
 877         unsigned char *ptr, *optr;
 878         u16 hdrflags;
 879         u32 tunnel_id, session_id;
 880         u16 version;
 881         int length;
 882
 883         /* UDP has verifed checksum */
 884
 885         /* UDP always verifies the packet length. */
 886         __skb_pull(skb, sizeof(struct udphdr));
 887
 888         /* Short packet? */
 889         if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
 890                 l2tp_info(tunnel, L2TP_MSG_DATA,
 891                           "%s: recv short packet (len=%d)\n",
 892                           tunnel->name, skb->len);
 893                 goto error;
 894         }
 895
 896         /* Trace packet contents, if enabled */
 897         if (tunnel->debug & L2TP_MSG_DATA) {
 898                 length = min(32u, skb->len);
 899                 if (!pskb_may_pull(skb, length))
 900                         goto error;
 901
 902                 pr_debug("%s: recv\n", tunnel->name);
 903                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
 904         }
 905
 906         /* Point to L2TP header */
 907         optr = ptr = skb->data;
 908
 909         /* Get L2TP header flags */
 910         hdrflags = ntohs(*(__be16 *) ptr);
 911
 912         /* Check protocol version */
 913         version = hdrflags & L2TP_HDR_VER_MASK;
 914         if (version != tunnel->version) {
 915                 l2tp_info(tunnel, L2TP_MSG_DATA,
 916                           "%s: recv protocol version mismatch: got %d expected %d\n",
 917                           tunnel->name, version, tunnel->version);
 918                 goto error;
 919         }
 920
 921         /* Get length of L2TP packet */
 922         length = skb->len;
 923
 924         /* If type is control packet, it is handled by userspace. */
 925         if (hdrflags & L2TP_HDRFLAG_T) {
 926                 l2tp_dbg(tunnel, L2TP_MSG_DATA,
 927                          "%s: recv control packet, len=%d\n",
 928                          tunnel->name, length);
 929                 goto error;
 930         }
 931
 932         /* Skip flags */
 933         ptr += 2;
 934
 935         if (tunnel->version == L2TP_HDR_VER_2) {
 936                 /* If length is present, skip it */
 937                 if (hdrflags & L2TP_HDRFLAG_L)
 938                         ptr += 2;
 939
 940                 /* Extract tunnel and session ID */
 941                 tunnel_id = ntohs(*(__be16 *) ptr);
 942                 ptr += 2;
 943                 session_id = ntohs(*(__be16 *) ptr);
 944                 ptr += 2;
 945         } else {
 946                 ptr += 2;       /* skip reserved bits */
 947                 tunnel_id = tunnel->tunnel_id;
 948                 session_id = ntohl(*(__be32 *) ptr);
 949                 ptr += 4;
 950         }
 951
 952         /* Find the session context */
 953         session = l2tp_session_get(tunnel->l2tp_net, tunnel, session_id, true);
 954         if (!session || !session->recv_skb) {
 955                 if (session) {
 956                         if (session->deref)
 957                                 session->deref(session);
 958                         l2tp_session_dec_refcount(session);
 959                 }
 960
 961                 /* Not found? Pass to userspace to deal with */
 962                 l2tp_info(tunnel, L2TP_MSG_DATA,
 963                           "%s: no session found (%u/%u). Passing up.\n",
 964                           tunnel->name, tunnel_id, session_id);
 965                 goto error;
 966         }
 967
 968         l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
 969         l2tp_session_dec_refcount(session);
 970
 971         return 0;
 972
 973 error:
 974         /* Put UDP header back */
 975         __skb_push(skb, sizeof(struct udphdr));
 976
 977         return 1;
 978 }
 979
 980 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
 981  * Return codes:
 982  * 0 : success.
 983  * <0: error
 984  * >0: skb should be passed up to userspace as UDP.
 985  */
 986 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 987 {
 988         struct l2tp_tunnel *tunnel;
 989
 990         tunnel = l2tp_sock_to_tunnel(sk);
 991         if (tunnel == NULL)
 992                 goto pass_up;
 993
 994         l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
 995                  tunnel->name, skb->len);
 996
 997         if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
 998                 goto pass_up_put;
 999
1000         sock_put(sk);
1001         return 0;
1002
1003 pass_up_put:
1004         sock_put(sk);
1005 pass_up:
1006         return 1;
1007 }
1008 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
1009
1010 /************************************************************************
1011  * Transmit handling
1012  ***********************************************************************/
1013
1014 /* Build an L2TP header for the session into the buffer provided.
1015  */
1016 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
1017 {
1018         struct l2tp_tunnel *tunnel = session->tunnel;
1019         __be16 *bufp = buf;
1020         __be16 *optr = buf;
1021         u16 flags = L2TP_HDR_VER_2;
1022         u32 tunnel_id = tunnel->peer_tunnel_id;
1023         u32 session_id = session->peer_session_id;
1024
1025         if (session->send_seq)
1026                 flags |= L2TP_HDRFLAG_S;
1027
1028         /* Setup L2TP header. */
1029         *bufp++ = htons(flags);
1030         *bufp++ = htons(tunnel_id);
1031         *bufp++ = htons(session_id);
1032         if (session->send_seq) {
1033                 *bufp++ = htons(session->ns);
1034                 *bufp++ = 0;
1035                 session->ns++;
1036                 session->ns &= 0xffff;
1037                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
1038                          session->name, session->ns);
1039         }
1040
1041         return bufp - optr;
1042 }
1043
1044 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
1045 {
1046         struct l2tp_tunnel *tunnel = session->tunnel;
1047         char *bufp = buf;
1048         char *optr = bufp;
1049
1050         /* Setup L2TP header. The header differs slightly for UDP and
1051          * IP encapsulations. For UDP, there is 4 bytes of flags.
1052          */
1053         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
1054                 u16 flags = L2TP_HDR_VER_3;
1055                 *((__be16 *) bufp) = htons(flags);
1056                 bufp += 2;
1057                 *((__be16 *) bufp) = 0;
1058                 bufp += 2;
1059         }
1060
1061         *((__be32 *) bufp) = htonl(session->peer_session_id);
1062         bufp += 4;
1063         if (session->cookie_len) {
1064                 memcpy(bufp, &session->cookie[0], session->cookie_len);
1065                 bufp += session->cookie_len;
1066         }
1067         if (session->l2specific_len) {
1068                 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
1069                         u32 l2h = 0;
1070                         if (session->send_seq) {
1071                                 l2h = 0x40000000 | session->ns;
1072                                 session->ns++;
1073                                 session->ns &= 0xffffff;
1074                                 l2tp_dbg(session, L2TP_MSG_SEQ,
1075                                          "%s: updated ns to %u\n",
1076                                          session->name, session->ns);
1077                         }
1078
1079                         *((__be32 *) bufp) = htonl(l2h);
1080                 }
1081                 bufp += session->l2specific_len;
1082         }
1083         if (session->offset)
1084                 bufp += session->offset;
1085
1086         return bufp - optr;
1087 }
1088
1089 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1090                           struct flowi *fl, size_t data_len)
1091 {
1092         struct l2tp_tunnel *tunnel = session->tunnel;
1093         unsigned int len = skb->len;
1094         int error;
1095
1096         /* Debug */
1097         if (session->send_seq)
1098                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes, ns=%u\n",
1099                          session->name, data_len, session->ns - 1);
1100         else
1101                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes\n",
1102                          session->name, data_len);
1103
1104         if (session->debug & L2TP_MSG_DATA) {
1105                 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1106                 unsigned char *datap = skb->data + uhlen;
1107
1108                 pr_debug("%s: xmit\n", session->name);
1109                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1110                                      datap, min_t(size_t, 32, len - uhlen));
1111         }
1112
1113         /* Queue the packet to IP for output */
1114         skb->ignore_df = 1;
1115 #if IS_ENABLED(CONFIG_IPV6)
1116         if (tunnel->sock->sk_family == PF_INET6 && !tunnel->v4mapped)
1117                 error = inet6_csk_xmit(tunnel->sock, skb, NULL);
1118         else
1119 #endif
1120                 error = ip_queue_xmit(tunnel->sock, skb, fl);
1121
1122         /* Update stats */
1123         if (error >= 0) {
1124                 atomic_long_inc(&tunnel->stats.tx_packets);
1125                 atomic_long_add(len, &tunnel->stats.tx_bytes);
1126                 atomic_long_inc(&session->stats.tx_packets);
1127                 atomic_long_add(len, &session->stats.tx_bytes);
1128         } else {
1129                 atomic_long_inc(&tunnel->stats.tx_errors);
1130                 atomic_long_inc(&session->stats.tx_errors);
1131         }
1132
1133         return 0;
1134 }
1135
1136 /* If caller requires the skb to have a ppp header, the header must be
1137  * inserted in the skb data before calling this function.
1138  */
1139 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1140 {
1141         int data_len = skb->len;
1142         struct l2tp_tunnel *tunnel = session->tunnel;
1143         struct sock *sk = tunnel->sock;
1144         struct flowi *fl;
1145         struct udphdr *uh;
1146         struct inet_sock *inet;
1147         int headroom;
1148         int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1149         int udp_len;
1150         int ret = NET_XMIT_SUCCESS;
1151
1152         /* Check that there's enough headroom in the skb to insert IP,
1153          * UDP and L2TP headers. If not enough, expand it to
1154          * make room. Adjust truesize.
1155          */
1156         headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1157                 uhlen + hdr_len;
1158         if (skb_cow_head(skb, headroom)) {
1159                 kfree_skb(skb);
1160                 return NET_XMIT_DROP;
1161         }
1162
1163         /* Setup L2TP header */
1164         session->build_header(session, __skb_push(skb, hdr_len));
1165
1166         /* Reset skb netfilter state */
1167         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1168         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1169                               IPSKB_REROUTED);
1170         nf_reset(skb);
1171
1172         bh_lock_sock(sk);
1173         if (sock_owned_by_user(sk)) {
1174                 kfree_skb(skb);
1175                 ret = NET_XMIT_DROP;
1176                 goto out_unlock;
1177         }
1178
1179         /* Get routing info from the tunnel socket */
1180         skb_dst_drop(skb);
1181         skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
1182
1183         inet = inet_sk(sk);
1184         fl = &inet->cork.fl;
1185         switch (tunnel->encap) {
1186         case L2TP_ENCAPTYPE_UDP:
1187                 /* Setup UDP header */
1188                 __skb_push(skb, sizeof(*uh));
1189                 skb_reset_transport_header(skb);
1190                 uh = udp_hdr(skb);
1191                 uh->source = inet->inet_sport;
1192                 uh->dest = inet->inet_dport;
1193                 udp_len = uhlen + hdr_len + data_len;
1194                 uh->len = htons(udp_len);
1195
1196                 /* Calculate UDP checksum if configured to do so */
1197 #if IS_ENABLED(CONFIG_IPV6)
1198                 if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
1199                         udp6_set_csum(udp_get_no_check6_tx(sk),
1200                                       skb, &inet6_sk(sk)->saddr,
1201                                       &sk->sk_v6_daddr, udp_len);
1202                 else
1203 #endif
1204                 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr,
1205                              inet->inet_daddr, udp_len);
1206                 break;
1207
1208         case L2TP_ENCAPTYPE_IP:
1209                 break;
1210         }
1211
1212         l2tp_xmit_core(session, skb, fl, data_len);
1213 out_unlock:
1214         bh_unlock_sock(sk);
1215
1216         return ret;
1217 }
1218 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1219
1220 /*****************************************************************************
1221  * Tinnel and session create/destroy.
1222  *****************************************************************************/
1223
1224 /* Tunnel socket destruct hook.
1225  * The tunnel context is deleted only when all session sockets have been
1226  * closed.
1227  */
1228 static void l2tp_tunnel_destruct(struct sock *sk)
1229 {
1230         struct l2tp_tunnel *tunnel = l2tp_tunnel(sk);
1231         struct l2tp_net *pn;
1232
1233         if (tunnel == NULL)
1234                 goto end;
1235
1236         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1237
1238
1239         /* Disable udp encapsulation */
1240         switch (tunnel->encap) {
1241         case L2TP_ENCAPTYPE_UDP:
1242                 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1243                 (udp_sk(sk))->encap_type = 0;
1244                 (udp_sk(sk))->encap_rcv = NULL;
1245                 (udp_sk(sk))->encap_destroy = NULL;
1246                 break;
1247         case L2TP_ENCAPTYPE_IP:
1248                 break;
1249         }
1250
1251         /* Remove hooks into tunnel socket */
1252         sk->sk_destruct = tunnel->old_sk_destruct;
1253         sk->sk_user_data = NULL;
1254         tunnel->sock = NULL;
1255
1256         /* Remove the tunnel struct from the tunnel list */
1257         pn = l2tp_pernet(tunnel->l2tp_net);
1258         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1259         list_del_rcu(&tunnel->list);
1260         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1261         atomic_dec(&l2tp_tunnel_count);
1262
1263         l2tp_tunnel_closeall(tunnel);
1264         l2tp_tunnel_dec_refcount(tunnel);
1265
1266         /* Call the original destructor */
1267         if (sk->sk_destruct)
1268                 (*sk->sk_destruct)(sk);
1269 end:
1270         return;
1271 }
1272
1273 /* When the tunnel is closed, all the attached sessions need to go too.
1274  */
1275 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1276 {
1277         int hash;
1278         struct hlist_node *walk;
1279         struct hlist_node *tmp;
1280         struct l2tp_session *session;
1281
1282         BUG_ON(tunnel == NULL);
1283
1284         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1285                   tunnel->name);
1286
1287         write_lock_bh(&tunnel->hlist_lock);
1288         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1289 again:
1290                 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1291                         session = hlist_entry(walk, struct l2tp_session, hlist);
1292
1293                         l2tp_info(session, L2TP_MSG_CONTROL,
1294                                   "%s: closing session\n", session->name);
1295
1296                         hlist_del_init(&session->hlist);
1297
1298                         if (session->ref != NULL)
1299                                 (*session->ref)(session);
1300
1301                         write_unlock_bh(&tunnel->hlist_lock);
1302
1303                         __l2tp_session_unhash(session);
1304                         l2tp_session_queue_purge(session);
1305
1306                         if (session->session_close != NULL)
1307                                 (*session->session_close)(session);
1308
1309                         if (session->deref != NULL)
1310                                 (*session->deref)(session);
1311
1312                         l2tp_session_dec_refcount(session);
1313
1314                         write_lock_bh(&tunnel->hlist_lock);
1315
1316                         /* Now restart from the beginning of this hash
1317                          * chain.  We always remove a session from the
1318                          * list so we are guaranteed to make forward
1319                          * progress.
1320                          */
1321                         goto again;
1322                 }
1323         }
1324         write_unlock_bh(&tunnel->hlist_lock);
1325 }
1326 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
1327
1328 /* Tunnel socket destroy hook for UDP encapsulation */
1329 static void l2tp_udp_encap_destroy(struct sock *sk)
1330 {
1331         struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
1332         if (tunnel) {
1333                 l2tp_tunnel_closeall(tunnel);
1334                 sock_put(sk);
1335         }
1336 }
1337
1338 /* Workqueue tunnel deletion function */
1339 static void l2tp_tunnel_del_work(struct work_struct *work)
1340 {
1341         struct l2tp_tunnel *tunnel = NULL;
1342         struct socket *sock = NULL;
1343         struct sock *sk = NULL;
1344
1345         tunnel = container_of(work, struct l2tp_tunnel, del_work);
1346
1347         l2tp_tunnel_closeall(tunnel);
1348
1349         sk = l2tp_tunnel_sock_lookup(tunnel);
1350         if (!sk)
1351                 goto out;
1352
1353         sock = sk->sk_socket;
1354
1355         /* If the tunnel socket was created by userspace, then go through the
1356          * inet layer to shut the socket down, and let userspace close it.
1357          * Otherwise, if we created the socket directly within the kernel, use
1358          * the sk API to release it here.
1359          * In either case the tunnel resources are freed in the socket
1360          * destructor when the tunnel socket goes away.
1361          */
1362         if (tunnel->fd >= 0) {
1363                 if (sock)
1364                         inet_shutdown(sock, 2);
1365         } else {
1366                 if (sock) {
1367                         kernel_sock_shutdown(sock, SHUT_RDWR);
1368                         sock_release(sock);
1369                 }
1370         }
1371
1372         l2tp_tunnel_sock_put(sk);
1373 out:
1374         l2tp_tunnel_dec_refcount(tunnel);
1375 }
1376
1377 /* Create a socket for the tunnel, if one isn't set up by
1378  * userspace. This is used for static tunnels where there is no
1379  * managing L2TP daemon.
1380  *
1381  * Since we don't want these sockets to keep a namespace alive by
1382  * themselves, we drop the socket's namespace refcount after creation.
1383  * These sockets are freed when the namespace exits using the pernet
1384  * exit hook.
1385  */
1386 static int l2tp_tunnel_sock_create(struct net *net,
1387                                 u32 tunnel_id,
1388                                 u32 peer_tunnel_id,
1389                                 struct l2tp_tunnel_cfg *cfg,
1390                                 struct socket **sockp)
1391 {
1392         int err = -EINVAL;
1393         struct socket *sock = NULL;
1394         struct udp_port_cfg udp_conf;
1395
1396         switch (cfg->encap) {
1397         case L2TP_ENCAPTYPE_UDP:
1398                 memset(&udp_conf, 0, sizeof(udp_conf));
1399
1400 #if IS_ENABLED(CONFIG_IPV6)
1401                 if (cfg->local_ip6 && cfg->peer_ip6) {
1402                         udp_conf.family = AF_INET6;
1403                         memcpy(&udp_conf.local_ip6, cfg->local_ip6,
1404                                sizeof(udp_conf.local_ip6));
1405                         memcpy(&udp_conf.peer_ip6, cfg->peer_ip6,
1406                                sizeof(udp_conf.peer_ip6));
1407                         udp_conf.use_udp6_tx_checksums =
1408                           ! cfg->udp6_zero_tx_checksums;
1409                         udp_conf.use_udp6_rx_checksums =
1410                           ! cfg->udp6_zero_rx_checksums;
1411                 } else
1412 #endif
1413                 {
1414                         udp_conf.family = AF_INET;
1415                         udp_conf.local_ip = cfg->local_ip;
1416                         udp_conf.peer_ip = cfg->peer_ip;
1417                         udp_conf.use_udp_checksums = cfg->use_udp_checksums;
1418                 }
1419
1420                 udp_conf.local_udp_port = htons(cfg->local_udp_port);
1421                 udp_conf.peer_udp_port = htons(cfg->peer_udp_port);
1422
1423                 err = udp_sock_create(net, &udp_conf, &sock);
1424                 if (err < 0)
1425                         goto out;
1426
1427                 break;
1428
1429         case L2TP_ENCAPTYPE_IP:
1430 #if IS_ENABLED(CONFIG_IPV6)
1431                 if (cfg->local_ip6 && cfg->peer_ip6) {
1432                         struct sockaddr_l2tpip6 ip6_addr = {0};
1433
1434                         err = sock_create_kern(net, AF_INET6, SOCK_DGRAM,
1435                                           IPPROTO_L2TP, &sock);
1436                         if (err < 0)
1437                                 goto out;
1438
1439                         ip6_addr.l2tp_family = AF_INET6;
1440                         memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1441                                sizeof(ip6_addr.l2tp_addr));
1442                         ip6_addr.l2tp_conn_id = tunnel_id;
1443                         err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1444                                           sizeof(ip6_addr));
1445                         if (err < 0)
1446                                 goto out;
1447
1448                         ip6_addr.l2tp_family = AF_INET6;
1449                         memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1450                                sizeof(ip6_addr.l2tp_addr));
1451                         ip6_addr.l2tp_conn_id = peer_tunnel_id;
1452                         err = kernel_connect(sock,
1453                                              (struct sockaddr *) &ip6_addr,
1454                                              sizeof(ip6_addr), 0);
1455                         if (err < 0)
1456                                 goto out;
1457                 } else
1458 #endif
1459                 {
1460                         struct sockaddr_l2tpip ip_addr = {0};
1461
1462                         err = sock_create_kern(net, AF_INET, SOCK_DGRAM,
1463                                           IPPROTO_L2TP, &sock);
1464                         if (err < 0)
1465                                 goto out;
1466
1467                         ip_addr.l2tp_family = AF_INET;
1468                         ip_addr.l2tp_addr = cfg->local_ip;
1469                         ip_addr.l2tp_conn_id = tunnel_id;
1470                         err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1471                                           sizeof(ip_addr));
1472                         if (err < 0)
1473                                 goto out;
1474
1475                         ip_addr.l2tp_family = AF_INET;
1476                         ip_addr.l2tp_addr = cfg->peer_ip;
1477                         ip_addr.l2tp_conn_id = peer_tunnel_id;
1478                         err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1479                                              sizeof(ip_addr), 0);
1480                         if (err < 0)
1481                                 goto out;
1482                 }
1483                 break;
1484
1485         default:
1486                 goto out;
1487         }
1488
1489 out:
1490         *sockp = sock;
1491         if ((err < 0) && sock) {
1492                 kernel_sock_shutdown(sock, SHUT_RDWR);
1493                 sock_release(sock);
1494                 *sockp = NULL;
1495         }
1496
1497         return err;
1498 }
1499
1500 static struct lock_class_key l2tp_socket_class;
1501
1502 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp)
1503 {
1504         struct l2tp_tunnel *tunnel = NULL;
1505         int err;
1506         struct socket *sock = NULL;
1507         struct sock *sk = NULL;
1508         struct l2tp_net *pn;
1509         enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1510
1511         /* Get the tunnel socket from the fd, which was opened by
1512          * the userspace L2TP daemon. If not specified, create a
1513          * kernel socket.
1514          */
1515         if (fd < 0) {
1516                 err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id,
1517                                 cfg, &sock);
1518                 if (err < 0)
1519                         goto err;
1520         } else {
1521                 sock = sockfd_lookup(fd, &err);
1522                 if (!sock) {
1523                         pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n",
1524                                tunnel_id, fd, err);
1525                         err = -EBADF;
1526                         goto err;
1527                 }
1528
1529                 /* Reject namespace mismatches */
1530                 if (!net_eq(sock_net(sock->sk), net)) {
1531                         pr_err("tunl %u: netns mismatch\n", tunnel_id);
1532                         err = -EINVAL;
1533                         goto err;
1534                 }
1535         }
1536
1537         sk = sock->sk;
1538
1539         if (cfg != NULL)
1540                 encap = cfg->encap;
1541
1542         /* Quick sanity checks */
1543         switch (encap) {
1544         case L2TP_ENCAPTYPE_UDP:
1545                 err = -EPROTONOSUPPORT;
1546                 if (sk->sk_protocol != IPPROTO_UDP) {
1547                         pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1548                                tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1549                         goto err;
1550                 }
1551                 break;
1552         case L2TP_ENCAPTYPE_IP:
1553                 err = -EPROTONOSUPPORT;
1554                 if (sk->sk_protocol != IPPROTO_L2TP) {
1555                         pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1556                                tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1557                         goto err;
1558                 }
1559                 break;
1560         }
1561
1562         /* Check if this socket has already been prepped */
1563         tunnel = l2tp_tunnel(sk);
1564         if (tunnel != NULL) {
1565                 /* This socket has already been prepped */
1566                 err = -EBUSY;
1567                 goto err;
1568         }
1569
1570         tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1571         if (tunnel == NULL) {
1572                 err = -ENOMEM;
1573                 goto err;
1574         }
1575
1576         tunnel->version = version;
1577         tunnel->tunnel_id = tunnel_id;
1578         tunnel->peer_tunnel_id = peer_tunnel_id;
1579         tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1580
1581         tunnel->magic = L2TP_TUNNEL_MAGIC;
1582         sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1583         rwlock_init(&tunnel->hlist_lock);
1584
1585         /* The net we belong to */
1586         tunnel->l2tp_net = net;
1587         pn = l2tp_pernet(net);
1588
1589         if (cfg != NULL)
1590                 tunnel->debug = cfg->debug;
1591
1592 #if IS_ENABLED(CONFIG_IPV6)
1593         if (sk->sk_family == PF_INET6) {
1594                 struct ipv6_pinfo *np = inet6_sk(sk);
1595
1596                 if (ipv6_addr_v4mapped(&np->saddr) &&
1597                     ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
1598                         struct inet_sock *inet = inet_sk(sk);
1599
1600                         tunnel->v4mapped = true;
1601                         inet->inet_saddr = np->saddr.s6_addr32[3];
1602                         inet->inet_rcv_saddr = sk->sk_v6_rcv_saddr.s6_addr32[3];
1603                         inet->inet_daddr = sk->sk_v6_daddr.s6_addr32[3];
1604                 } else {
1605                         tunnel->v4mapped = false;
1606                 }
1607         }
1608 #endif
1609
1610         /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1611         tunnel->encap = encap;
1612         if (encap == L2TP_ENCAPTYPE_UDP) {
1613                 struct udp_tunnel_sock_cfg udp_cfg = { };
1614
1615                 udp_cfg.sk_user_data = tunnel;
1616                 udp_cfg.encap_type = UDP_ENCAP_L2TPINUDP;
1617                 udp_cfg.encap_rcv = l2tp_udp_encap_recv;
1618                 udp_cfg.encap_destroy = l2tp_udp_encap_destroy;
1619
1620                 setup_udp_tunnel_sock(net, sock, &udp_cfg);
1621         } else {
1622                 sk->sk_user_data = tunnel;
1623         }
1624
1625         /* Hook on the tunnel socket destructor so that we can cleanup
1626          * if the tunnel socket goes away.
1627          */
1628         tunnel->old_sk_destruct = sk->sk_destruct;
1629         sk->sk_destruct = &l2tp_tunnel_destruct;
1630         tunnel->sock = sk;
1631         tunnel->fd = fd;
1632         lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
1633
1634         sk->sk_allocation = GFP_ATOMIC;
1635
1636         /* Init delete workqueue struct */
1637         INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
1638
1639         /* Add tunnel to our list */
1640         INIT_LIST_HEAD(&tunnel->list);
1641         atomic_inc(&l2tp_tunnel_count);
1642
1643         /* Bump the reference count. The tunnel context is deleted
1644          * only when this drops to zero. Must be done before list insertion
1645          */
1646         refcount_set(&tunnel->ref_count, 1);
1647         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1648         list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1649         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1650
1651         err = 0;
1652 err:
1653         if (tunnelp)
1654                 *tunnelp = tunnel;
1655
1656         /* If tunnel's socket was created by the kernel, it doesn't
1657          *  have a file.
1658          */
1659         if (sock && sock->file)
1660                 sockfd_put(sock);
1661
1662         return err;
1663 }
1664 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1665
1666 /* This function is used by the netlink TUNNEL_DELETE command.
1667  */
1668 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1669 {
1670         l2tp_tunnel_inc_refcount(tunnel);
1671         if (false == queue_work(l2tp_wq, &tunnel->del_work)) {
1672                 l2tp_tunnel_dec_refcount(tunnel);
1673                 return 1;
1674         }
1675         return 0;
1676 }
1677 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1678
1679 /* Really kill the session.
1680  */
1681 void l2tp_session_free(struct l2tp_session *session)
1682 {
1683         struct l2tp_tunnel *tunnel = session->tunnel;
1684
1685         BUG_ON(refcount_read(&session->ref_count) != 0);
1686
1687         if (tunnel) {
1688                 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1689                 if (session->session_id != 0)
1690                         atomic_dec(&l2tp_session_count);
1691                 sock_put(tunnel->sock);
1692                 session->tunnel = NULL;
1693                 l2tp_tunnel_dec_refcount(tunnel);
1694         }
1695
1696         kfree(session);
1697 }
1698 EXPORT_SYMBOL_GPL(l2tp_session_free);
1699
1700 /* Remove an l2tp session from l2tp_core's hash lists.
1701  * Provides a tidyup interface for pseudowire code which can't just route all
1702  * shutdown via. l2tp_session_delete and a pseudowire-specific session_close
1703  * callback.
1704  */
1705 void __l2tp_session_unhash(struct l2tp_session *session)
1706 {
1707         struct l2tp_tunnel *tunnel = session->tunnel;
1708
1709         /* Remove the session from core hashes */
1710         if (tunnel) {
1711                 /* Remove from the per-tunnel hash */
1712                 write_lock_bh(&tunnel->hlist_lock);
1713                 hlist_del_init(&session->hlist);
1714                 write_unlock_bh(&tunnel->hlist_lock);
1715
1716                 /* For L2TPv3 we have a per-net hash: remove from there, too */
1717                 if (tunnel->version != L2TP_HDR_VER_2) {
1718                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1719                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1720                         hlist_del_init_rcu(&session->global_hlist);
1721                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1722                         synchronize_rcu();
1723                 }
1724         }
1725 }
1726 EXPORT_SYMBOL_GPL(__l2tp_session_unhash);
1727
1728 /* This function is used by the netlink SESSION_DELETE command and by
1729    pseudowire modules.
1730  */
1731 int l2tp_session_delete(struct l2tp_session *session)
1732 {
1733         if (session->ref)
1734                 (*session->ref)(session);
1735         __l2tp_session_unhash(session);
1736         l2tp_session_queue_purge(session);
1737         if (session->session_close != NULL)
1738                 (*session->session_close)(session);
1739         if (session->deref)
1740                 (*session->deref)(session);
1741         l2tp_session_dec_refcount(session);
1742         return 0;
1743 }
1744 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1745
1746 /* We come here whenever a session's send_seq, cookie_len or
1747  * l2specific_len parameters are set.
1748  */
1749 void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1750 {
1751         if (version == L2TP_HDR_VER_2) {
1752                 session->hdr_len = 6;
1753                 if (session->send_seq)
1754                         session->hdr_len += 4;
1755         } else {
1756                 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1757                 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1758                         session->hdr_len += 4;
1759         }
1760
1761 }
1762 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len);
1763
1764 struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
1765 {
1766         struct l2tp_session *session;
1767         int err;
1768
1769         session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1770         if (session != NULL) {
1771                 session->magic = L2TP_SESSION_MAGIC;
1772                 session->tunnel = tunnel;
1773
1774                 session->session_id = session_id;
1775                 session->peer_session_id = peer_session_id;
1776                 session->nr = 0;
1777                 if (tunnel->version == L2TP_HDR_VER_2)
1778                         session->nr_max = 0xffff;
1779                 else
1780                         session->nr_max = 0xffffff;
1781                 session->nr_window_size = session->nr_max / 2;
1782                 session->nr_oos_count_max = 4;
1783
1784                 /* Use NR of first received packet */
1785                 session->reorder_skip = 1;
1786
1787                 sprintf(&session->name[0], "sess %u/%u",
1788                         tunnel->tunnel_id, session->session_id);
1789
1790                 skb_queue_head_init(&session->reorder_q);
1791
1792                 INIT_HLIST_NODE(&session->hlist);
1793                 INIT_HLIST_NODE(&session->global_hlist);
1794
1795                 /* Inherit debug options from tunnel */
1796                 session->debug = tunnel->debug;
1797
1798                 if (cfg) {
1799                         session->pwtype = cfg->pw_type;
1800                         session->debug = cfg->debug;
1801                         session->mtu = cfg->mtu;
1802                         session->mru = cfg->mru;
1803                         session->send_seq = cfg->send_seq;
1804                         session->recv_seq = cfg->recv_seq;
1805                         session->lns_mode = cfg->lns_mode;
1806                         session->reorder_timeout = cfg->reorder_timeout;
1807                         session->offset = cfg->offset;
1808                         session->l2specific_type = cfg->l2specific_type;
1809                         session->l2specific_len = cfg->l2specific_len;
1810                         session->cookie_len = cfg->cookie_len;
1811                         memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1812                         session->peer_cookie_len = cfg->peer_cookie_len;
1813                         memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1814                 }
1815
1816                 if (tunnel->version == L2TP_HDR_VER_2)
1817                         session->build_header = l2tp_build_l2tpv2_header;
1818                 else
1819                         session->build_header = l2tp_build_l2tpv3_header;
1820
1821                 l2tp_session_set_header_len(session, tunnel->version);
1822
1823                 refcount_set(&session->ref_count, 1);
1824
1825                 err = l2tp_session_add_to_tunnel(tunnel, session);
1826                 if (err) {
1827                         kfree(session);
1828
1829                         return ERR_PTR(err);
1830                 }
1831
1832                 l2tp_tunnel_inc_refcount(tunnel);
1833
1834                 /* Ensure tunnel socket isn't deleted */
1835                 sock_hold(tunnel->sock);
1836
1837                 /* Ignore management session in session count value */
1838                 if (session->session_id != 0)
1839                         atomic_inc(&l2tp_session_count);
1840
1841                 return session;
1842         }
1843
1844         return ERR_PTR(-ENOMEM);
1845 }
1846 EXPORT_SYMBOL_GPL(l2tp_session_create);
1847
1848 /*****************************************************************************
1849  * Init and cleanup
1850  *****************************************************************************/
1851
1852 static __net_init int l2tp_init_net(struct net *net)
1853 {
1854         struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1855         int hash;
1856
1857         INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1858         spin_lock_init(&pn->l2tp_tunnel_list_lock);
1859
1860         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1861                 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1862
1863         spin_lock_init(&pn->l2tp_session_hlist_lock);
1864
1865         return 0;
1866 }
1867
1868 static __net_exit void l2tp_exit_net(struct net *net)
1869 {
1870         struct l2tp_net *pn = l2tp_pernet(net);
1871         struct l2tp_tunnel *tunnel = NULL;
1872
1873         rcu_read_lock_bh();
1874         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
1875                 (void)l2tp_tunnel_delete(tunnel);
1876         }
1877         rcu_read_unlock_bh();
1878
1879         flush_workqueue(l2tp_wq);
1880         rcu_barrier();
1881 }
1882
1883 static struct pernet_operations l2tp_net_ops = {
1884         .init = l2tp_init_net,
1885         .exit = l2tp_exit_net,
1886         .id   = &l2tp_net_id,
1887         .size = sizeof(struct l2tp_net),
1888 };
1889
1890 static int __init l2tp_init(void)
1891 {
1892         int rc = 0;
1893
1894         rc = register_pernet_device(&l2tp_net_ops);
1895         if (rc)
1896                 goto out;
1897
1898         l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0);
1899         if (!l2tp_wq) {
1900                 pr_err("alloc_workqueue failed\n");
1901                 unregister_pernet_device(&l2tp_net_ops);
1902                 rc = -ENOMEM;
1903                 goto out;
1904         }
1905
1906         pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
1907
1908 out:
1909         return rc;
1910 }
1911
1912 static void __exit l2tp_exit(void)
1913 {
1914         unregister_pernet_device(&l2tp_net_ops);
1915         if (l2tp_wq) {
1916                 destroy_workqueue(l2tp_wq);
1917                 l2tp_wq = NULL;
1918         }
1919 }
1920
1921 module_init(l2tp_init);
1922 module_exit(l2tp_exit);
1923
1924 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1925 MODULE_DESCRIPTION("L2TP core");
1926 MODULE_LICENSE("GPL");
1927 MODULE_VERSION(L2TP_DRV_VERSION);
1928