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_MAX               14
  87
  88 /* Default trace flags */
  89 #define L2TP_DEFAULT_DEBUG_FLAGS        0
  90
  91 /* Private data stored for received packets in the skb.
  92  */
  93 struct l2tp_skb_cb {
  94         u32                     ns;
  95         u16                     has_seq;
  96         u16                     length;
  97         unsigned long           expires;
  98 };
  99
 100 #define L2TP_SKB_CB(skb)        ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
 101
 102 static atomic_t l2tp_tunnel_count;
 103 static atomic_t l2tp_session_count;
 104 static struct workqueue_struct *l2tp_wq;
 105
 106 /* per-net private data for this module */
 107 static unsigned int l2tp_net_id;
 108 struct l2tp_net {
 109         struct list_head l2tp_tunnel_list;
 110         spinlock_t l2tp_tunnel_list_lock;
 111         struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
 112         spinlock_t l2tp_session_hlist_lock;
 113 };
 114
 115
 116 static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk)
 117 {
 118         return sk->sk_user_data;
 119 }
 120
 121 static inline struct l2tp_net *l2tp_pernet(const struct net *net)
 122 {
 123         BUG_ON(!net);
 124
 125         return net_generic(net, l2tp_net_id);
 126 }
 127
 128 /* Session hash global list for L2TPv3.
 129  * The session_id SHOULD be random according to RFC3931, but several
 130  * L2TP implementations use incrementing session_ids.  So we do a real
 131  * hash on the session_id, rather than a simple bitmask.
 132  */
 133 static inline struct hlist_head *
 134 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
 135 {
 136         return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
 137
 138 }
 139
 140 /* Lookup the tunnel socket, possibly involving the fs code if the socket is
 141  * owned by userspace.  A struct sock returned from this function must be
 142  * released using l2tp_tunnel_sock_put once you're done with it.
 143  */
 144 static struct sock *l2tp_tunnel_sock_lookup(struct l2tp_tunnel *tunnel)
 145 {
 146         int err = 0;
 147         struct socket *sock = NULL;
 148         struct sock *sk = NULL;
 149
 150         if (!tunnel)
 151                 goto out;
 152
 153         if (tunnel->fd >= 0) {
 154                 /* Socket is owned by userspace, who might be in the process
 155                  * of closing it.  Look the socket up using the fd to ensure
 156                  * consistency.
 157                  */
 158                 sock = sockfd_lookup(tunnel->fd, &err);
 159                 if (sock)
 160                         sk = sock->sk;
 161         } else {
 162                 /* Socket is owned by kernelspace */
 163                 sk = tunnel->sock;
 164                 sock_hold(sk);
 165         }
 166
 167 out:
 168         return sk;
 169 }
 170
 171 /* Drop a reference to a tunnel socket obtained via. l2tp_tunnel_sock_put */
 172 static void l2tp_tunnel_sock_put(struct sock *sk)
 173 {
 174         struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
 175         if (tunnel) {
 176                 if (tunnel->fd >= 0) {
 177                         /* Socket is owned by userspace */
 178                         sockfd_put(sk->sk_socket);
 179                 }
 180                 sock_put(sk);
 181         }
 182         sock_put(sk);
 183 }
 184
 185 /* Session hash list.
 186  * The session_id SHOULD be random according to RFC2661, but several
 187  * L2TP implementations (Cisco and Microsoft) use incrementing
 188  * session_ids.  So we do a real hash on the session_id, rather than a
 189  * simple bitmask.
 190  */
 191 static inline struct hlist_head *
 192 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
 193 {
 194         return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
 195 }
 196
 197 /* Lookup a tunnel. A new reference is held on the returned tunnel. */
 198 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id)
 199 {
 200         const struct l2tp_net *pn = l2tp_pernet(net);
 201         struct l2tp_tunnel *tunnel;
 202
 203         rcu_read_lock_bh();
 204         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 205                 if (tunnel->tunnel_id == tunnel_id) {
 206                         l2tp_tunnel_inc_refcount(tunnel);
 207                         rcu_read_unlock_bh();
 208
 209                         return tunnel;
 210                 }
 211         }
 212         rcu_read_unlock_bh();
 213
 214         return NULL;
 215 }
 216 EXPORT_SYMBOL_GPL(l2tp_tunnel_get);
 217
 218 /* Lookup a session. A new reference is held on the returned session.
 219  * Optionally calls session->ref() too if do_ref is true.
 220  */
 221 struct l2tp_session *l2tp_session_get(const struct net *net,
 222                                       struct l2tp_tunnel *tunnel,
 223                                       u32 session_id, bool do_ref)
 224 {
 225         struct hlist_head *session_list;
 226         struct l2tp_session *session;
 227
 228         if (!tunnel) {
 229                 struct l2tp_net *pn = l2tp_pernet(net);
 230
 231                 session_list = l2tp_session_id_hash_2(pn, session_id);
 232
 233                 rcu_read_lock_bh();
 234                 hlist_for_each_entry_rcu(session, session_list, global_hlist) {
 235                         if (session->session_id == session_id) {
 236                                 l2tp_session_inc_refcount(session);
 237                                 if (do_ref && session->ref)
 238                                         session->ref(session);
 239                                 rcu_read_unlock_bh();
 240
 241                                 return session;
 242                         }
 243                 }
 244                 rcu_read_unlock_bh();
 245
 246                 return NULL;
 247         }
 248
 249         session_list = l2tp_session_id_hash(tunnel, session_id);
 250         read_lock_bh(&tunnel->hlist_lock);
 251         hlist_for_each_entry(session, session_list, hlist) {
 252                 if (session->session_id == session_id) {
 253                         l2tp_session_inc_refcount(session);
 254                         if (do_ref && session->ref)
 255                                 session->ref(session);
 256                         read_unlock_bh(&tunnel->hlist_lock);
 257
 258                         return session;
 259                 }
 260         }
 261         read_unlock_bh(&tunnel->hlist_lock);
 262
 263         return NULL;
 264 }
 265 EXPORT_SYMBOL_GPL(l2tp_session_get);
 266
 267 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth,
 268                                           bool do_ref)
 269 {
 270         int hash;
 271         struct l2tp_session *session;
 272         int count = 0;
 273
 274         read_lock_bh(&tunnel->hlist_lock);
 275         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
 276                 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) {
 277                         if (++count > nth) {
 278                                 l2tp_session_inc_refcount(session);
 279                                 if (do_ref && session->ref)
 280                                         session->ref(session);
 281                                 read_unlock_bh(&tunnel->hlist_lock);
 282                                 return session;
 283                         }
 284                 }
 285         }
 286
 287         read_unlock_bh(&tunnel->hlist_lock);
 288
 289         return NULL;
 290 }
 291 EXPORT_SYMBOL_GPL(l2tp_session_get_nth);
 292
 293 /* Lookup a session by interface name.
 294  * This is very inefficient but is only used by management interfaces.
 295  */
 296 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 297                                                 const char *ifname,
 298                                                 bool do_ref)
 299 {
 300         struct l2tp_net *pn = l2tp_pernet(net);
 301         int hash;
 302         struct l2tp_session *session;
 303
 304         rcu_read_lock_bh();
 305         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
 306                 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) {
 307                         if (!strcmp(session->ifname, ifname)) {
 308                                 l2tp_session_inc_refcount(session);
 309                                 if (do_ref && session->ref)
 310                                         session->ref(session);
 311                                 rcu_read_unlock_bh();
 312
 313                                 return session;
 314                         }
 315                 }
 316         }
 317
 318         rcu_read_unlock_bh();
 319
 320         return NULL;
 321 }
 322 EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname);
 323
 324 int l2tp_session_register(struct l2tp_session *session,
 325                           struct l2tp_tunnel *tunnel)
 326 {
 327         struct l2tp_session *session_walk;
 328         struct hlist_head *g_head;
 329         struct hlist_head *head;
 330         struct l2tp_net *pn;
 331         int err;
 332
 333         head = l2tp_session_id_hash(tunnel, session->session_id);
 334
 335         write_lock_bh(&tunnel->hlist_lock);
 336         if (!tunnel->acpt_newsess) {
 337                 err = -ENODEV;
 338                 goto err_tlock;
 339         }
 340
 341         hlist_for_each_entry(session_walk, head, hlist)
 342                 if (session_walk->session_id == session->session_id) {
 343                         err = -EEXIST;
 344                         goto err_tlock;
 345                 }
 346
 347         if (tunnel->version == L2TP_HDR_VER_3) {
 348                 pn = l2tp_pernet(tunnel->l2tp_net);
 349                 g_head = l2tp_session_id_hash_2(l2tp_pernet(tunnel->l2tp_net),
 350                                                 session->session_id);
 351
 352                 spin_lock_bh(&pn->l2tp_session_hlist_lock);
 353
 354                 /* IP encap expects session IDs to be globally unique, while
 355                  * UDP encap doesn't.
 356                  */
 357                 hlist_for_each_entry(session_walk, g_head, global_hlist)
 358                         if (session_walk->session_id == session->session_id &&
 359                             (session_walk->tunnel->encap == L2TP_ENCAPTYPE_IP ||
 360                              tunnel->encap == L2TP_ENCAPTYPE_IP)) {
 361                                 err = -EEXIST;
 362                                 goto err_tlock_pnlock;
 363                         }
 364
 365                 l2tp_tunnel_inc_refcount(tunnel);
 366                 sock_hold(tunnel->sock);
 367                 hlist_add_head_rcu(&session->global_hlist, g_head);
 368
 369                 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
 370         } else {
 371                 l2tp_tunnel_inc_refcount(tunnel);
 372                 sock_hold(tunnel->sock);
 373         }
 374
 375         hlist_add_head(&session->hlist, head);
 376         write_unlock_bh(&tunnel->hlist_lock);
 377
 378         /* Ignore management session in session count value */
 379         if (session->session_id != 0)
 380                 atomic_inc(&l2tp_session_count);
 381
 382         return 0;
 383
 384 err_tlock_pnlock:
 385         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
 386 err_tlock:
 387         write_unlock_bh(&tunnel->hlist_lock);
 388
 389         return err;
 390 }
 391 EXPORT_SYMBOL_GPL(l2tp_session_register);
 392
 393 /* Lookup a tunnel by id
 394  */
 395 struct l2tp_tunnel *l2tp_tunnel_find(const struct net *net, u32 tunnel_id)
 396 {
 397         struct l2tp_tunnel *tunnel;
 398         struct l2tp_net *pn = l2tp_pernet(net);
 399
 400         rcu_read_lock_bh();
 401         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 402                 if (tunnel->tunnel_id == tunnel_id) {
 403                         rcu_read_unlock_bh();
 404                         return tunnel;
 405                 }
 406         }
 407         rcu_read_unlock_bh();
 408
 409         return NULL;
 410 }
 411 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
 412
 413 struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth)
 414 {
 415         struct l2tp_net *pn = l2tp_pernet(net);
 416         struct l2tp_tunnel *tunnel;
 417         int count = 0;
 418
 419         rcu_read_lock_bh();
 420         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 421                 if (++count > nth) {
 422                         rcu_read_unlock_bh();
 423                         return tunnel;
 424                 }
 425         }
 426
 427         rcu_read_unlock_bh();
 428
 429         return NULL;
 430 }
 431 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
 432
 433 /*****************************************************************************
 434  * Receive data handling
 435  *****************************************************************************/
 436
 437 /* Queue a skb in order. We come here only if the skb has an L2TP sequence
 438  * number.
 439  */
 440 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
 441 {
 442         struct sk_buff *skbp;
 443         struct sk_buff *tmp;
 444         u32 ns = L2TP_SKB_CB(skb)->ns;
 445
 446         spin_lock_bh(&session->reorder_q.lock);
 447         skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
 448                 if (L2TP_SKB_CB(skbp)->ns > ns) {
 449                         __skb_queue_before(&session->reorder_q, skbp, skb);
 450                         l2tp_dbg(session, L2TP_MSG_SEQ,
 451                                  "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
 452                                  session->name, ns, L2TP_SKB_CB(skbp)->ns,
 453                                  skb_queue_len(&session->reorder_q));
 454                         atomic_long_inc(&session->stats.rx_oos_packets);
 455                         goto out;
 456                 }
 457         }
 458
 459         __skb_queue_tail(&session->reorder_q, skb);
 460
 461 out:
 462         spin_unlock_bh(&session->reorder_q.lock);
 463 }
 464
 465 /* Dequeue a single skb.
 466  */
 467 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
 468 {
 469         struct l2tp_tunnel *tunnel = session->tunnel;
 470         int length = L2TP_SKB_CB(skb)->length;
 471
 472         /* We're about to requeue the skb, so return resources
 473          * to its current owner (a socket receive buffer).
 474          */
 475         skb_orphan(skb);
 476
 477         atomic_long_inc(&tunnel->stats.rx_packets);
 478         atomic_long_add(length, &tunnel->stats.rx_bytes);
 479         atomic_long_inc(&session->stats.rx_packets);
 480         atomic_long_add(length, &session->stats.rx_bytes);
 481
 482         if (L2TP_SKB_CB(skb)->has_seq) {
 483                 /* Bump our Nr */
 484                 session->nr++;
 485                 session->nr &= session->nr_max;
 486
 487                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
 488                          session->name, session->nr);
 489         }
 490
 491         /* call private receive handler */
 492         if (session->recv_skb != NULL)
 493                 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
 494         else
 495                 kfree_skb(skb);
 496
 497         if (session->deref)
 498                 (*session->deref)(session);
 499 }
 500
 501 /* Dequeue skbs from the session's reorder_q, subject to packet order.
 502  * Skbs that have been in the queue for too long are simply discarded.
 503  */
 504 static void l2tp_recv_dequeue(struct l2tp_session *session)
 505 {
 506         struct sk_buff *skb;
 507         struct sk_buff *tmp;
 508
 509         /* If the pkt at the head of the queue has the nr that we
 510          * expect to send up next, dequeue it and any other
 511          * in-sequence packets behind it.
 512          */
 513 start:
 514         spin_lock_bh(&session->reorder_q.lock);
 515         skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
 516                 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
 517                         atomic_long_inc(&session->stats.rx_seq_discards);
 518                         atomic_long_inc(&session->stats.rx_errors);
 519                         l2tp_dbg(session, L2TP_MSG_SEQ,
 520                                  "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
 521                                  session->name, L2TP_SKB_CB(skb)->ns,
 522                                  L2TP_SKB_CB(skb)->length, session->nr,
 523                                  skb_queue_len(&session->reorder_q));
 524                         session->reorder_skip = 1;
 525                         __skb_unlink(skb, &session->reorder_q);
 526                         kfree_skb(skb);
 527                         if (session->deref)
 528                                 (*session->deref)(session);
 529                         continue;
 530                 }
 531
 532                 if (L2TP_SKB_CB(skb)->has_seq) {
 533                         if (session->reorder_skip) {
 534                                 l2tp_dbg(session, L2TP_MSG_SEQ,
 535                                          "%s: advancing nr to next pkt: %u -> %u",
 536                                          session->name, session->nr,
 537                                          L2TP_SKB_CB(skb)->ns);
 538                                 session->reorder_skip = 0;
 539                                 session->nr = L2TP_SKB_CB(skb)->ns;
 540                         }
 541                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
 542                                 l2tp_dbg(session, L2TP_MSG_SEQ,
 543                                          "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
 544                                          session->name, L2TP_SKB_CB(skb)->ns,
 545                                          L2TP_SKB_CB(skb)->length, session->nr,
 546                                          skb_queue_len(&session->reorder_q));
 547                                 goto out;
 548                         }
 549                 }
 550                 __skb_unlink(skb, &session->reorder_q);
 551
 552                 /* Process the skb. We release the queue lock while we
 553                  * do so to let other contexts process the queue.
 554                  */
 555                 spin_unlock_bh(&session->reorder_q.lock);
 556                 l2tp_recv_dequeue_skb(session, skb);
 557                 goto start;
 558         }
 559
 560 out:
 561         spin_unlock_bh(&session->reorder_q.lock);
 562 }
 563
 564 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr)
 565 {
 566         u32 nws;
 567
 568         if (nr >= session->nr)
 569                 nws = nr - session->nr;
 570         else
 571                 nws = (session->nr_max + 1) - (session->nr - nr);
 572
 573         return nws < session->nr_window_size;
 574 }
 575
 576 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if
 577  * acceptable, else non-zero.
 578  */
 579 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
 580 {
 581         if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) {
 582                 /* Packet sequence number is outside allowed window.
 583                  * Discard it.
 584                  */
 585                 l2tp_dbg(session, L2TP_MSG_SEQ,
 586                          "%s: pkt %u len %d discarded, outside window, nr=%u\n",
 587                          session->name, L2TP_SKB_CB(skb)->ns,
 588                          L2TP_SKB_CB(skb)->length, session->nr);
 589                 goto discard;
 590         }
 591
 592         if (session->reorder_timeout != 0) {
 593                 /* Packet reordering enabled. Add skb to session's
 594                  * reorder queue, in order of ns.
 595                  */
 596                 l2tp_recv_queue_skb(session, skb);
 597                 goto out;
 598         }
 599
 600         /* Packet reordering disabled. Discard out-of-sequence packets, while
 601          * tracking the number if in-sequence packets after the first OOS packet
 602          * is seen. After nr_oos_count_max in-sequence packets, reset the
 603          * sequence number to re-enable packet reception.
 604          */
 605         if (L2TP_SKB_CB(skb)->ns == session->nr) {
 606                 skb_queue_tail(&session->reorder_q, skb);
 607         } else {
 608                 u32 nr_oos = L2TP_SKB_CB(skb)->ns;
 609                 u32 nr_next = (session->nr_oos + 1) & session->nr_max;
 610
 611                 if (nr_oos == nr_next)
 612                         session->nr_oos_count++;
 613                 else
 614                         session->nr_oos_count = 0;
 615
 616                 session->nr_oos = nr_oos;
 617                 if (session->nr_oos_count > session->nr_oos_count_max) {
 618                         session->reorder_skip = 1;
 619                         l2tp_dbg(session, L2TP_MSG_SEQ,
 620                                  "%s: %d oos packets received. Resetting sequence numbers\n",
 621                                  session->name, session->nr_oos_count);
 622                 }
 623                 if (!session->reorder_skip) {
 624                         atomic_long_inc(&session->stats.rx_seq_discards);
 625                         l2tp_dbg(session, L2TP_MSG_SEQ,
 626                                  "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
 627                                  session->name, L2TP_SKB_CB(skb)->ns,
 628                                  L2TP_SKB_CB(skb)->length, session->nr,
 629                                  skb_queue_len(&session->reorder_q));
 630                         goto discard;
 631                 }
 632                 skb_queue_tail(&session->reorder_q, skb);
 633         }
 634
 635 out:
 636         return 0;
 637
 638 discard:
 639         return 1;
 640 }
 641
 642 /* Do receive processing of L2TP data frames. We handle both L2TPv2
 643  * and L2TPv3 data frames here.
 644  *
 645  * L2TPv2 Data Message Header
 646  *
 647  *  0                   1                   2                   3
 648  *  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
 649  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 650  * |T|L|x|x|S|x|O|P|x|x|x|x|  Ver  |          Length (opt)         |
 651  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 652  * |           Tunnel ID           |           Session ID          |
 653  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 654  * |             Ns (opt)          |             Nr (opt)          |
 655  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 656  * |      Offset Size (opt)        |    Offset pad... (opt)
 657  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 658  *
 659  * Data frames are marked by T=0. All other fields are the same as
 660  * those in L2TP control frames.
 661  *
 662  * L2TPv3 Data Message Header
 663  *
 664  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 665  * |                      L2TP Session Header                      |
 666  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 667  * |                      L2-Specific Sublayer                     |
 668  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 669  * |                        Tunnel Payload                      ...
 670  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 671  *
 672  * L2TPv3 Session Header Over IP
 673  *
 674  *  0                   1                   2                   3
 675  *  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
 676  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 677  * |                           Session ID                          |
 678  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 679  * |               Cookie (optional, maximum 64 bits)...
 680  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 681  *                                                                 |
 682  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 683  *
 684  * L2TPv3 L2-Specific Sublayer Format
 685  *
 686  *  0                   1                   2                   3
 687  *  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
 688  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 689  * |x|S|x|x|x|x|x|x|              Sequence Number                  |
 690  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 691  *
 692  * Cookie value, sublayer format and offset (pad) are negotiated with
 693  * the peer when the session is set up. Unlike L2TPv2, we do not need
 694  * to parse the packet header to determine if optional fields are
 695  * present.
 696  *
 697  * Caller must already have parsed the frame and determined that it is
 698  * a data (not control) frame before coming here. Fields up to the
 699  * session-id have already been parsed and ptr points to the data
 700  * after the session-id.
 701  *
 702  * session->ref() must have been called prior to l2tp_recv_common().
 703  * session->deref() will be called automatically after skb is processed.
 704  */
 705 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 706                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 707                       int length, int (*payload_hook)(struct sk_buff *skb))
 708 {
 709         struct l2tp_tunnel *tunnel = session->tunnel;
 710         int offset;
 711         u32 ns, nr;
 712
 713         /* Parse and check optional cookie */
 714         if (session->peer_cookie_len > 0) {
 715                 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
 716                         l2tp_info(tunnel, L2TP_MSG_DATA,
 717                                   "%s: cookie mismatch (%u/%u). Discarding.\n",
 718                                   tunnel->name, tunnel->tunnel_id,
 719                                   session->session_id);
 720                         atomic_long_inc(&session->stats.rx_cookie_discards);
 721                         goto discard;
 722                 }
 723                 ptr += session->peer_cookie_len;
 724         }
 725
 726         /* Handle the optional sequence numbers. Sequence numbers are
 727          * in different places for L2TPv2 and L2TPv3.
 728          *
 729          * If we are the LAC, enable/disable sequence numbers under
 730          * the control of the LNS.  If no sequence numbers present but
 731          * we were expecting them, discard frame.
 732          */
 733         ns = nr = 0;
 734         L2TP_SKB_CB(skb)->has_seq = 0;
 735         if (tunnel->version == L2TP_HDR_VER_2) {
 736                 if (hdrflags & L2TP_HDRFLAG_S) {
 737                         ns = ntohs(*(__be16 *) ptr);
 738                         ptr += 2;
 739                         nr = ntohs(*(__be16 *) ptr);
 740                         ptr += 2;
 741
 742                         /* Store L2TP info in the skb */
 743                         L2TP_SKB_CB(skb)->ns = ns;
 744                         L2TP_SKB_CB(skb)->has_seq = 1;
 745
 746                         l2tp_dbg(session, L2TP_MSG_SEQ,
 747                                  "%s: recv data ns=%u, nr=%u, session nr=%u\n",
 748                                  session->name, ns, nr, session->nr);
 749                 }
 750         } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
 751                 u32 l2h = ntohl(*(__be32 *) ptr);
 752
 753                 if (l2h & 0x40000000) {
 754                         ns = l2h & 0x00ffffff;
 755
 756                         /* Store L2TP info in the skb */
 757                         L2TP_SKB_CB(skb)->ns = ns;
 758                         L2TP_SKB_CB(skb)->has_seq = 1;
 759
 760                         l2tp_dbg(session, L2TP_MSG_SEQ,
 761                                  "%s: recv data ns=%u, session nr=%u\n",
 762                                  session->name, ns, session->nr);
 763                 }
 764                 ptr += 4;
 765         }
 766
 767         if (L2TP_SKB_CB(skb)->has_seq) {
 768                 /* Received a packet with sequence numbers. If we're the LNS,
 769                  * check if we sre sending sequence numbers and if not,
 770                  * configure it so.
 771                  */
 772                 if ((!session->lns_mode) && (!session->send_seq)) {
 773                         l2tp_info(session, L2TP_MSG_SEQ,
 774                                   "%s: requested to enable seq numbers by LNS\n",
 775                                   session->name);
 776                         session->send_seq = -1;
 777                         l2tp_session_set_header_len(session, tunnel->version);
 778                 }
 779         } else {
 780                 /* No sequence numbers.
 781                  * If user has configured mandatory sequence numbers, discard.
 782                  */
 783                 if (session->recv_seq) {
 784                         l2tp_warn(session, L2TP_MSG_SEQ,
 785                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 786                                   session->name);
 787                         atomic_long_inc(&session->stats.rx_seq_discards);
 788                         goto discard;
 789                 }
 790
 791                 /* If we're the LAC and we're sending sequence numbers, the
 792                  * LNS has requested that we no longer send sequence numbers.
 793                  * If we're the LNS and we're sending sequence numbers, the
 794                  * LAC is broken. Discard the frame.
 795                  */
 796                 if ((!session->lns_mode) && (session->send_seq)) {
 797                         l2tp_info(session, L2TP_MSG_SEQ,
 798                                   "%s: requested to disable seq numbers by LNS\n",
 799                                   session->name);
 800                         session->send_seq = 0;
 801                         l2tp_session_set_header_len(session, tunnel->version);
 802                 } else if (session->send_seq) {
 803                         l2tp_warn(session, L2TP_MSG_SEQ,
 804                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 805                                   session->name);
 806                         atomic_long_inc(&session->stats.rx_seq_discards);
 807                         goto discard;
 808                 }
 809         }
 810
 811         /* Session data offset is handled differently for L2TPv2 and
 812          * L2TPv3. For L2TPv2, there is an optional 16-bit value in
 813          * the header. For L2TPv3, the offset is negotiated using AVPs
 814          * in the session setup control protocol.
 815          */
 816         if (tunnel->version == L2TP_HDR_VER_2) {
 817                 /* If offset bit set, skip it. */
 818                 if (hdrflags & L2TP_HDRFLAG_O) {
 819                         offset = ntohs(*(__be16 *)ptr);
 820                         ptr += 2 + offset;
 821                 }
 822         } else
 823                 ptr += session->offset;
 824
 825         offset = ptr - optr;
 826         if (!pskb_may_pull(skb, offset))
 827                 goto discard;
 828
 829         __skb_pull(skb, offset);
 830
 831         /* If caller wants to process the payload before we queue the
 832          * packet, do so now.
 833          */
 834         if (payload_hook)
 835                 if ((*payload_hook)(skb))
 836                         goto discard;
 837
 838         /* Prepare skb for adding to the session's reorder_q.  Hold
 839          * packets for max reorder_timeout or 1 second if not
 840          * reordering.
 841          */
 842         L2TP_SKB_CB(skb)->length = length;
 843         L2TP_SKB_CB(skb)->expires = jiffies +
 844                 (session->reorder_timeout ? session->reorder_timeout : HZ);
 845
 846         /* Add packet to the session's receive queue. Reordering is done here, if
 847          * enabled. Saved L2TP protocol info is stored in skb->sb[].
 848          */
 849         if (L2TP_SKB_CB(skb)->has_seq) {
 850                 if (l2tp_recv_data_seq(session, skb))
 851                         goto discard;
 852         } else {
 853                 /* No sequence numbers. Add the skb to the tail of the
 854                  * reorder queue. This ensures that it will be
 855                  * delivered after all previous sequenced skbs.
 856                  */
 857                 skb_queue_tail(&session->reorder_q, skb);
 858         }
 859
 860         /* Try to dequeue as many skbs from reorder_q as we can. */
 861         l2tp_recv_dequeue(session);
 862
 863         return;
 864
 865 discard:
 866         atomic_long_inc(&session->stats.rx_errors);
 867         kfree_skb(skb);
 868
 869         if (session->deref)
 870                 (*session->deref)(session);
 871 }
 872 EXPORT_SYMBOL(l2tp_recv_common);
 873
 874 /* Drop skbs from the session's reorder_q
 875  */
 876 int l2tp_session_queue_purge(struct l2tp_session *session)
 877 {
 878         struct sk_buff *skb = NULL;
 879         BUG_ON(!session);
 880         BUG_ON(session->magic != L2TP_SESSION_MAGIC);
 881         while ((skb = skb_dequeue(&session->reorder_q))) {
 882                 atomic_long_inc(&session->stats.rx_errors);
 883                 kfree_skb(skb);
 884                 if (session->deref)
 885                         (*session->deref)(session);
 886         }
 887         return 0;
 888 }
 889 EXPORT_SYMBOL_GPL(l2tp_session_queue_purge);
 890
 891 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
 892  * here. The skb is not on a list when we get here.
 893  * Returns 0 if the packet was a data packet and was successfully passed on.
 894  * Returns 1 if the packet was not a good data packet and could not be
 895  * forwarded.  All such packets are passed up to userspace to deal with.
 896  */
 897 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
 898                               int (*payload_hook)(struct sk_buff *skb))
 899 {
 900         struct l2tp_session *session = NULL;
 901         unsigned char *ptr, *optr;
 902         u16 hdrflags;
 903         u32 tunnel_id, session_id;
 904         u16 version;
 905         int length;
 906
 907         /* UDP has verifed checksum */
 908
 909         /* UDP always verifies the packet length. */
 910         __skb_pull(skb, sizeof(struct udphdr));
 911
 912         /* Short packet? */
 913         if (!pskb_may_pull(skb, L2TP_HDR_SIZE_MAX)) {
 914                 l2tp_info(tunnel, L2TP_MSG_DATA,
 915                           "%s: recv short packet (len=%d)\n",
 916                           tunnel->name, skb->len);
 917                 goto error;
 918         }
 919
 920         /* Trace packet contents, if enabled */
 921         if (tunnel->debug & L2TP_MSG_DATA) {
 922                 length = min(32u, skb->len);
 923                 if (!pskb_may_pull(skb, length))
 924                         goto error;
 925
 926                 pr_debug("%s: recv\n", tunnel->name);
 927                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
 928         }
 929
 930         /* Point to L2TP header */
 931         optr = ptr = skb->data;
 932
 933         /* Get L2TP header flags */
 934         hdrflags = ntohs(*(__be16 *) ptr);
 935
 936         /* Check protocol version */
 937         version = hdrflags & L2TP_HDR_VER_MASK;
 938         if (version != tunnel->version) {
 939                 l2tp_info(tunnel, L2TP_MSG_DATA,
 940                           "%s: recv protocol version mismatch: got %d expected %d\n",
 941                           tunnel->name, version, tunnel->version);
 942                 goto error;
 943         }
 944
 945         /* Get length of L2TP packet */
 946         length = skb->len;
 947
 948         /* If type is control packet, it is handled by userspace. */
 949         if (hdrflags & L2TP_HDRFLAG_T) {
 950                 l2tp_dbg(tunnel, L2TP_MSG_DATA,
 951                          "%s: recv control packet, len=%d\n",
 952                          tunnel->name, length);
 953                 goto error;
 954         }
 955
 956         /* Skip flags */
 957         ptr += 2;
 958
 959         if (tunnel->version == L2TP_HDR_VER_2) {
 960                 /* If length is present, skip it */
 961                 if (hdrflags & L2TP_HDRFLAG_L)
 962                         ptr += 2;
 963
 964                 /* Extract tunnel and session ID */
 965                 tunnel_id = ntohs(*(__be16 *) ptr);
 966                 ptr += 2;
 967                 session_id = ntohs(*(__be16 *) ptr);
 968                 ptr += 2;
 969         } else {
 970                 ptr += 2;       /* skip reserved bits */
 971                 tunnel_id = tunnel->tunnel_id;
 972                 session_id = ntohl(*(__be32 *) ptr);
 973                 ptr += 4;
 974         }
 975
 976         /* Find the session context */
 977         session = l2tp_session_get(tunnel->l2tp_net, tunnel, session_id, true);
 978         if (!session || !session->recv_skb) {
 979                 if (session) {
 980                         if (session->deref)
 981                                 session->deref(session);
 982                         l2tp_session_dec_refcount(session);
 983                 }
 984
 985                 /* Not found? Pass to userspace to deal with */
 986                 l2tp_info(tunnel, L2TP_MSG_DATA,
 987                           "%s: no session found (%u/%u). Passing up.\n",
 988                           tunnel->name, tunnel_id, session_id);
 989                 goto error;
 990         }
 991
 992         if (tunnel->version == L2TP_HDR_VER_3 &&
 993             l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
 994                 goto error;
 995
 996         l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
 997         l2tp_session_dec_refcount(session);
 998
 999         return 0;
1000
1001 error:
1002         /* Put UDP header back */
1003         __skb_push(skb, sizeof(struct udphdr));
1004
1005         return 1;
1006 }
1007
1008 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
1009  * Return codes:
1010  * 0 : success.
1011  * <0: error
1012  * >0: skb should be passed up to userspace as UDP.
1013  */
1014 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
1015 {
1016         struct l2tp_tunnel *tunnel;
1017
1018         tunnel = l2tp_sock_to_tunnel(sk);
1019         if (tunnel == NULL)
1020                 goto pass_up;
1021
1022         l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
1023                  tunnel->name, skb->len);
1024
1025         if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
1026                 goto pass_up_put;
1027
1028         sock_put(sk);
1029         return 0;
1030
1031 pass_up_put:
1032         sock_put(sk);
1033 pass_up:
1034         return 1;
1035 }
1036 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
1037
1038 /************************************************************************
1039  * Transmit handling
1040  ***********************************************************************/
1041
1042 /* Build an L2TP header for the session into the buffer provided.
1043  */
1044 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
1045 {
1046         struct l2tp_tunnel *tunnel = session->tunnel;
1047         __be16 *bufp = buf;
1048         __be16 *optr = buf;
1049         u16 flags = L2TP_HDR_VER_2;
1050         u32 tunnel_id = tunnel->peer_tunnel_id;
1051         u32 session_id = session->peer_session_id;
1052
1053         if (session->send_seq)
1054                 flags |= L2TP_HDRFLAG_S;
1055
1056         /* Setup L2TP header. */
1057         *bufp++ = htons(flags);
1058         *bufp++ = htons(tunnel_id);
1059         *bufp++ = htons(session_id);
1060         if (session->send_seq) {
1061                 *bufp++ = htons(session->ns);
1062                 *bufp++ = 0;
1063                 session->ns++;
1064                 session->ns &= 0xffff;
1065                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
1066                          session->name, session->ns);
1067         }
1068
1069         return bufp - optr;
1070 }
1071
1072 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
1073 {
1074         struct l2tp_tunnel *tunnel = session->tunnel;
1075         char *bufp = buf;
1076         char *optr = bufp;
1077
1078         /* Setup L2TP header. The header differs slightly for UDP and
1079          * IP encapsulations. For UDP, there is 4 bytes of flags.
1080          */
1081         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
1082                 u16 flags = L2TP_HDR_VER_3;
1083                 *((__be16 *) bufp) = htons(flags);
1084                 bufp += 2;
1085                 *((__be16 *) bufp) = 0;
1086                 bufp += 2;
1087         }
1088
1089         *((__be32 *) bufp) = htonl(session->peer_session_id);
1090         bufp += 4;
1091         if (session->cookie_len) {
1092                 memcpy(bufp, &session->cookie[0], session->cookie_len);
1093                 bufp += session->cookie_len;
1094         }
1095         if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
1096                 u32 l2h = 0;
1097
1098                 if (session->send_seq) {
1099                         l2h = 0x40000000 | session->ns;
1100                         session->ns++;
1101                         session->ns &= 0xffffff;
1102                         l2tp_dbg(session, L2TP_MSG_SEQ,
1103                                  "%s: updated ns to %u\n",
1104                                  session->name, session->ns);
1105                 }
1106
1107                 *((__be32 *)bufp) = htonl(l2h);
1108                 bufp += 4;
1109         }
1110         if (session->offset)
1111                 bufp += session->offset;
1112
1113         return bufp - optr;
1114 }
1115
1116 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1117                           struct flowi *fl, size_t data_len)
1118 {
1119         struct l2tp_tunnel *tunnel = session->tunnel;
1120         unsigned int len = skb->len;
1121         int error;
1122
1123         /* Debug */
1124         if (session->send_seq)
1125                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n",
1126                          session->name, data_len, session->ns - 1);
1127         else
1128                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n",
1129                          session->name, data_len);
1130
1131         if (session->debug & L2TP_MSG_DATA) {
1132                 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1133                 unsigned char *datap = skb->data + uhlen;
1134
1135                 pr_debug("%s: xmit\n", session->name);
1136                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1137                                      datap, min_t(size_t, 32, len - uhlen));
1138         }
1139
1140         /* Queue the packet to IP for output */
1141         skb->ignore_df = 1;
1142         skb_dst_drop(skb);
1143 #if IS_ENABLED(CONFIG_IPV6)
1144         if (tunnel->sock->sk_family == PF_INET6 && !tunnel->v4mapped)
1145                 error = inet6_csk_xmit(tunnel->sock, skb, NULL);
1146         else
1147 #endif
1148                 error = ip_queue_xmit(tunnel->sock, skb, fl);
1149
1150         /* Update stats */
1151         if (error >= 0) {
1152                 atomic_long_inc(&tunnel->stats.tx_packets);
1153                 atomic_long_add(len, &tunnel->stats.tx_bytes);
1154                 atomic_long_inc(&session->stats.tx_packets);
1155                 atomic_long_add(len, &session->stats.tx_bytes);
1156         } else {
1157                 atomic_long_inc(&tunnel->stats.tx_errors);
1158                 atomic_long_inc(&session->stats.tx_errors);
1159         }
1160
1161         return 0;
1162 }
1163
1164 /* If caller requires the skb to have a ppp header, the header must be
1165  * inserted in the skb data before calling this function.
1166  */
1167 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1168 {
1169         int data_len = skb->len;
1170         struct l2tp_tunnel *tunnel = session->tunnel;
1171         struct sock *sk = tunnel->sock;
1172         struct flowi *fl;
1173         struct udphdr *uh;
1174         struct inet_sock *inet;
1175         int headroom;
1176         int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1177         int udp_len;
1178         int ret = NET_XMIT_SUCCESS;
1179
1180         /* Check that there's enough headroom in the skb to insert IP,
1181          * UDP and L2TP headers. If not enough, expand it to
1182          * make room. Adjust truesize.
1183          */
1184         headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1185                 uhlen + hdr_len;
1186         if (skb_cow_head(skb, headroom)) {
1187                 kfree_skb(skb);
1188                 return NET_XMIT_DROP;
1189         }
1190
1191         /* Setup L2TP header */
1192         session->build_header(session, __skb_push(skb, hdr_len));
1193
1194         /* Reset skb netfilter state */
1195         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1196         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1197                               IPSKB_REROUTED);
1198         nf_reset(skb);
1199
1200         bh_lock_sock(sk);
1201         if (sock_owned_by_user(sk)) {
1202                 kfree_skb(skb);
1203                 ret = NET_XMIT_DROP;
1204                 goto out_unlock;
1205         }
1206
1207         inet = inet_sk(sk);
1208         fl = &inet->cork.fl;
1209         switch (tunnel->encap) {
1210         case L2TP_ENCAPTYPE_UDP:
1211                 /* Setup UDP header */
1212                 __skb_push(skb, sizeof(*uh));
1213                 skb_reset_transport_header(skb);
1214                 uh = udp_hdr(skb);
1215                 uh->source = inet->inet_sport;
1216                 uh->dest = inet->inet_dport;
1217                 udp_len = uhlen + hdr_len + data_len;
1218                 uh->len = htons(udp_len);
1219
1220                 /* Calculate UDP checksum if configured to do so */
1221 #if IS_ENABLED(CONFIG_IPV6)
1222                 if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
1223                         udp6_set_csum(udp_get_no_check6_tx(sk),
1224                                       skb, &inet6_sk(sk)->saddr,
1225                                       &sk->sk_v6_daddr, udp_len);
1226                 else
1227 #endif
1228                 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr,
1229                              inet->inet_daddr, udp_len);
1230                 break;
1231
1232         case L2TP_ENCAPTYPE_IP:
1233                 break;
1234         }
1235
1236         l2tp_xmit_core(session, skb, fl, data_len);
1237 out_unlock:
1238         bh_unlock_sock(sk);
1239
1240         return ret;
1241 }
1242 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1243
1244 /*****************************************************************************
1245  * Tinnel and session create/destroy.
1246  *****************************************************************************/
1247
1248 /* Tunnel socket destruct hook.
1249  * The tunnel context is deleted only when all session sockets have been
1250  * closed.
1251  */
1252 static void l2tp_tunnel_destruct(struct sock *sk)
1253 {
1254         struct l2tp_tunnel *tunnel = l2tp_tunnel(sk);
1255         struct l2tp_net *pn;
1256
1257         if (tunnel == NULL)
1258                 goto end;
1259
1260         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1261
1262
1263         /* Disable udp encapsulation */
1264         switch (tunnel->encap) {
1265         case L2TP_ENCAPTYPE_UDP:
1266                 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1267                 (udp_sk(sk))->encap_type = 0;
1268                 (udp_sk(sk))->encap_rcv = NULL;
1269                 (udp_sk(sk))->encap_destroy = NULL;
1270                 break;
1271         case L2TP_ENCAPTYPE_IP:
1272                 break;
1273         }
1274
1275         /* Remove hooks into tunnel socket */
1276         sk->sk_destruct = tunnel->old_sk_destruct;
1277         sk->sk_user_data = NULL;
1278
1279         /* Remove the tunnel struct from the tunnel list */
1280         pn = l2tp_pernet(tunnel->l2tp_net);
1281         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1282         list_del_rcu(&tunnel->list);
1283         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1284         atomic_dec(&l2tp_tunnel_count);
1285
1286         l2tp_tunnel_closeall(tunnel);
1287
1288         tunnel->sock = NULL;
1289         l2tp_tunnel_dec_refcount(tunnel);
1290
1291         /* Call the original destructor */
1292         if (sk->sk_destruct)
1293                 (*sk->sk_destruct)(sk);
1294 end:
1295         return;
1296 }
1297
1298 /* When the tunnel is closed, all the attached sessions need to go too.
1299  */
1300 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1301 {
1302         int hash;
1303         struct hlist_node *walk;
1304         struct hlist_node *tmp;
1305         struct l2tp_session *session;
1306
1307         BUG_ON(tunnel == NULL);
1308
1309         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1310                   tunnel->name);
1311
1312         write_lock_bh(&tunnel->hlist_lock);
1313         tunnel->acpt_newsess = false;
1314         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1315 again:
1316                 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1317                         session = hlist_entry(walk, struct l2tp_session, hlist);
1318
1319                         l2tp_info(session, L2TP_MSG_CONTROL,
1320                                   "%s: closing session\n", session->name);
1321
1322                         hlist_del_init(&session->hlist);
1323
1324                         if (test_and_set_bit(0, &session->dead))
1325                                 goto again;
1326
1327                         if (session->ref != NULL)
1328                                 (*session->ref)(session);
1329
1330                         write_unlock_bh(&tunnel->hlist_lock);
1331
1332                         __l2tp_session_unhash(session);
1333                         l2tp_session_queue_purge(session);
1334
1335                         if (session->session_close != NULL)
1336                                 (*session->session_close)(session);
1337
1338                         if (session->deref != NULL)
1339                                 (*session->deref)(session);
1340
1341                         l2tp_session_dec_refcount(session);
1342
1343                         write_lock_bh(&tunnel->hlist_lock);
1344
1345                         /* Now restart from the beginning of this hash
1346                          * chain.  We always remove a session from the
1347                          * list so we are guaranteed to make forward
1348                          * progress.
1349                          */
1350                         goto again;
1351                 }
1352         }
1353         write_unlock_bh(&tunnel->hlist_lock);
1354 }
1355 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
1356
1357 /* Tunnel socket destroy hook for UDP encapsulation */
1358 static void l2tp_udp_encap_destroy(struct sock *sk)
1359 {
1360         struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
1361         if (tunnel) {
1362                 l2tp_tunnel_closeall(tunnel);
1363                 sock_put(sk);
1364         }
1365 }
1366
1367 /* Workqueue tunnel deletion function */
1368 static void l2tp_tunnel_del_work(struct work_struct *work)
1369 {
1370         struct l2tp_tunnel *tunnel = NULL;
1371         struct socket *sock = NULL;
1372         struct sock *sk = NULL;
1373
1374         tunnel = container_of(work, struct l2tp_tunnel, del_work);
1375
1376         l2tp_tunnel_closeall(tunnel);
1377
1378         sk = l2tp_tunnel_sock_lookup(tunnel);
1379         if (!sk)
1380                 goto out;
1381
1382         sock = sk->sk_socket;
1383
1384         /* If the tunnel socket was created by userspace, then go through the
1385          * inet layer to shut the socket down, and let userspace close it.
1386          * Otherwise, if we created the socket directly within the kernel, use
1387          * the sk API to release it here.
1388          * In either case the tunnel resources are freed in the socket
1389          * destructor when the tunnel socket goes away.
1390          */
1391         if (tunnel->fd >= 0) {
1392                 if (sock)
1393                         inet_shutdown(sock, 2);
1394         } else {
1395                 if (sock) {
1396                         kernel_sock_shutdown(sock, SHUT_RDWR);
1397                         sock_release(sock);
1398                 }
1399         }
1400
1401         l2tp_tunnel_sock_put(sk);
1402 out:
1403         l2tp_tunnel_dec_refcount(tunnel);
1404 }
1405
1406 /* Create a socket for the tunnel, if one isn't set up by
1407  * userspace. This is used for static tunnels where there is no
1408  * managing L2TP daemon.
1409  *
1410  * Since we don't want these sockets to keep a namespace alive by
1411  * themselves, we drop the socket's namespace refcount after creation.
1412  * These sockets are freed when the namespace exits using the pernet
1413  * exit hook.
1414  */
1415 static int l2tp_tunnel_sock_create(struct net *net,
1416                                 u32 tunnel_id,
1417                                 u32 peer_tunnel_id,
1418                                 struct l2tp_tunnel_cfg *cfg,
1419                                 struct socket **sockp)
1420 {
1421         int err = -EINVAL;
1422         struct socket *sock = NULL;
1423         struct udp_port_cfg udp_conf;
1424
1425         switch (cfg->encap) {
1426         case L2TP_ENCAPTYPE_UDP:
1427                 memset(&udp_conf, 0, sizeof(udp_conf));
1428
1429 #if IS_ENABLED(CONFIG_IPV6)
1430                 if (cfg->local_ip6 && cfg->peer_ip6) {
1431                         udp_conf.family = AF_INET6;
1432                         memcpy(&udp_conf.local_ip6, cfg->local_ip6,
1433                                sizeof(udp_conf.local_ip6));
1434                         memcpy(&udp_conf.peer_ip6, cfg->peer_ip6,
1435                                sizeof(udp_conf.peer_ip6));
1436                         udp_conf.use_udp6_tx_checksums =
1437                             cfg->udp6_zero_tx_checksums;
1438                         udp_conf.use_udp6_rx_checksums =
1439                             cfg->udp6_zero_rx_checksums;
1440                 } else
1441 #endif
1442                 {
1443                         udp_conf.family = AF_INET;
1444                         udp_conf.local_ip = cfg->local_ip;
1445                         udp_conf.peer_ip = cfg->peer_ip;
1446                         udp_conf.use_udp_checksums = cfg->use_udp_checksums;
1447                 }
1448
1449                 udp_conf.local_udp_port = htons(cfg->local_udp_port);
1450                 udp_conf.peer_udp_port = htons(cfg->peer_udp_port);
1451
1452                 err = udp_sock_create(net, &udp_conf, &sock);
1453                 if (err < 0)
1454                         goto out;
1455
1456                 break;
1457
1458         case L2TP_ENCAPTYPE_IP:
1459 #if IS_ENABLED(CONFIG_IPV6)
1460                 if (cfg->local_ip6 && cfg->peer_ip6) {
1461                         struct sockaddr_l2tpip6 ip6_addr = {0};
1462
1463                         err = sock_create_kern(net, AF_INET6, SOCK_DGRAM,
1464                                           IPPROTO_L2TP, &sock);
1465                         if (err < 0)
1466                                 goto out;
1467
1468                         ip6_addr.l2tp_family = AF_INET6;
1469                         memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1470                                sizeof(ip6_addr.l2tp_addr));
1471                         ip6_addr.l2tp_conn_id = tunnel_id;
1472                         err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1473                                           sizeof(ip6_addr));
1474                         if (err < 0)
1475                                 goto out;
1476
1477                         ip6_addr.l2tp_family = AF_INET6;
1478                         memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1479                                sizeof(ip6_addr.l2tp_addr));
1480                         ip6_addr.l2tp_conn_id = peer_tunnel_id;
1481                         err = kernel_connect(sock,
1482                                              (struct sockaddr *) &ip6_addr,
1483                                              sizeof(ip6_addr), 0);
1484                         if (err < 0)
1485                                 goto out;
1486                 } else
1487 #endif
1488                 {
1489                         struct sockaddr_l2tpip ip_addr = {0};
1490
1491                         err = sock_create_kern(net, AF_INET, SOCK_DGRAM,
1492                                           IPPROTO_L2TP, &sock);
1493                         if (err < 0)
1494                                 goto out;
1495
1496                         ip_addr.l2tp_family = AF_INET;
1497                         ip_addr.l2tp_addr = cfg->local_ip;
1498                         ip_addr.l2tp_conn_id = tunnel_id;
1499                         err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1500                                           sizeof(ip_addr));
1501                         if (err < 0)
1502                                 goto out;
1503
1504                         ip_addr.l2tp_family = AF_INET;
1505                         ip_addr.l2tp_addr = cfg->peer_ip;
1506                         ip_addr.l2tp_conn_id = peer_tunnel_id;
1507                         err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1508                                              sizeof(ip_addr), 0);
1509                         if (err < 0)
1510                                 goto out;
1511                 }
1512                 break;
1513
1514         default:
1515                 goto out;
1516         }
1517
1518 out:
1519         *sockp = sock;
1520         if ((err < 0) && sock) {
1521                 kernel_sock_shutdown(sock, SHUT_RDWR);
1522                 sock_release(sock);
1523                 *sockp = NULL;
1524         }
1525
1526         return err;
1527 }
1528
1529 static struct lock_class_key l2tp_socket_class;
1530
1531 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)
1532 {
1533         struct l2tp_tunnel *tunnel = NULL;
1534         int err;
1535         struct socket *sock = NULL;
1536         struct sock *sk = NULL;
1537         struct l2tp_net *pn;
1538         enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1539
1540         /* Get the tunnel socket from the fd, which was opened by
1541          * the userspace L2TP daemon. If not specified, create a
1542          * kernel socket.
1543          */
1544         if (fd < 0) {
1545                 err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id,
1546                                 cfg, &sock);
1547                 if (err < 0)
1548                         goto err;
1549         } else {
1550                 sock = sockfd_lookup(fd, &err);
1551                 if (!sock) {
1552                         pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n",
1553                                tunnel_id, fd, err);
1554                         err = -EBADF;
1555                         goto err;
1556                 }
1557
1558                 /* Reject namespace mismatches */
1559                 if (!net_eq(sock_net(sock->sk), net)) {
1560                         pr_err("tunl %u: netns mismatch\n", tunnel_id);
1561                         err = -EINVAL;
1562                         goto err;
1563                 }
1564         }
1565
1566         sk = sock->sk;
1567
1568         if (cfg != NULL)
1569                 encap = cfg->encap;
1570
1571         /* Quick sanity checks */
1572         err = -EPROTONOSUPPORT;
1573         if (sk->sk_type != SOCK_DGRAM) {
1574                 pr_debug("tunl %hu: fd %d wrong socket type\n",
1575                          tunnel_id, fd);
1576                 goto err;
1577         }
1578         if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6)
1579                 goto err;
1580         switch (encap) {
1581         case L2TP_ENCAPTYPE_UDP:
1582                 if (sk->sk_protocol != IPPROTO_UDP) {
1583                         pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1584                                tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1585                         goto err;
1586                 }
1587                 break;
1588         case L2TP_ENCAPTYPE_IP:
1589                 if (sk->sk_protocol != IPPROTO_L2TP) {
1590                         pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1591                                tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1592                         goto err;
1593                 }
1594                 break;
1595         }
1596
1597         /* Check if this socket has already been prepped */
1598         tunnel = l2tp_tunnel(sk);
1599         if (tunnel != NULL) {
1600                 /* This socket has already been prepped */
1601                 err = -EBUSY;
1602                 goto err;
1603         }
1604
1605         tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1606         if (tunnel == NULL) {
1607                 err = -ENOMEM;
1608                 goto err;
1609         }
1610
1611         tunnel->version = version;
1612         tunnel->tunnel_id = tunnel_id;
1613         tunnel->peer_tunnel_id = peer_tunnel_id;
1614         tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1615
1616         tunnel->magic = L2TP_TUNNEL_MAGIC;
1617         sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1618         rwlock_init(&tunnel->hlist_lock);
1619         tunnel->acpt_newsess = true;
1620
1621         /* The net we belong to */
1622         tunnel->l2tp_net = net;
1623         pn = l2tp_pernet(net);
1624
1625         if (cfg != NULL)
1626                 tunnel->debug = cfg->debug;
1627
1628 #if IS_ENABLED(CONFIG_IPV6)
1629         if (sk->sk_family == PF_INET6) {
1630                 struct ipv6_pinfo *np = inet6_sk(sk);
1631
1632                 if (ipv6_addr_v4mapped(&np->saddr) &&
1633                     ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
1634                         struct inet_sock *inet = inet_sk(sk);
1635
1636                         tunnel->v4mapped = true;
1637                         inet->inet_saddr = np->saddr.s6_addr32[3];
1638                         inet->inet_rcv_saddr = sk->sk_v6_rcv_saddr.s6_addr32[3];
1639                         inet->inet_daddr = sk->sk_v6_daddr.s6_addr32[3];
1640                 } else {
1641                         tunnel->v4mapped = false;
1642                 }
1643         }
1644 #endif
1645
1646         /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1647         tunnel->encap = encap;
1648         if (encap == L2TP_ENCAPTYPE_UDP) {
1649                 struct udp_tunnel_sock_cfg udp_cfg = { };
1650
1651                 udp_cfg.sk_user_data = tunnel;
1652                 udp_cfg.encap_type = UDP_ENCAP_L2TPINUDP;
1653                 udp_cfg.encap_rcv = l2tp_udp_encap_recv;
1654                 udp_cfg.encap_destroy = l2tp_udp_encap_destroy;
1655
1656                 setup_udp_tunnel_sock(net, sock, &udp_cfg);
1657         } else {
1658                 sk->sk_user_data = tunnel;
1659         }
1660
1661         /* Hook on the tunnel socket destructor so that we can cleanup
1662          * if the tunnel socket goes away.
1663          */
1664         tunnel->old_sk_destruct = sk->sk_destruct;
1665         sk->sk_destruct = &l2tp_tunnel_destruct;
1666         tunnel->sock = sk;
1667         tunnel->fd = fd;
1668         lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
1669
1670         sk->sk_allocation = GFP_ATOMIC;
1671
1672         /* Init delete workqueue struct */
1673         INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
1674
1675         /* Add tunnel to our list */
1676         INIT_LIST_HEAD(&tunnel->list);
1677         atomic_inc(&l2tp_tunnel_count);
1678
1679         /* Bump the reference count. The tunnel context is deleted
1680          * only when this drops to zero. Must be done before list insertion
1681          */
1682         l2tp_tunnel_inc_refcount(tunnel);
1683         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1684         list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1685         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1686
1687         err = 0;
1688 err:
1689         if (tunnelp)
1690                 *tunnelp = tunnel;
1691
1692         /* If tunnel's socket was created by the kernel, it doesn't
1693          *  have a file.
1694          */
1695         if (sock && sock->file)
1696                 sockfd_put(sock);
1697
1698         return err;
1699 }
1700 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1701
1702 /* This function is used by the netlink TUNNEL_DELETE command.
1703  */
1704 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1705 {
1706         if (!test_and_set_bit(0, &tunnel->dead)) {
1707                 l2tp_tunnel_inc_refcount(tunnel);
1708                 queue_work(l2tp_wq, &tunnel->del_work);
1709         }
1710 }
1711 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1712
1713 /* Really kill the session.
1714  */
1715 void l2tp_session_free(struct l2tp_session *session)
1716 {
1717         struct l2tp_tunnel *tunnel = session->tunnel;
1718
1719         BUG_ON(atomic_read(&session->ref_count) != 0);
1720
1721         if (tunnel) {
1722                 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1723                 if (session->session_id != 0)
1724                         atomic_dec(&l2tp_session_count);
1725                 sock_put(tunnel->sock);
1726                 session->tunnel = NULL;
1727                 l2tp_tunnel_dec_refcount(tunnel);
1728         }
1729
1730         kfree(session);
1731 }
1732 EXPORT_SYMBOL_GPL(l2tp_session_free);
1733
1734 /* Remove an l2tp session from l2tp_core's hash lists.
1735  * Provides a tidyup interface for pseudowire code which can't just route all
1736  * shutdown via. l2tp_session_delete and a pseudowire-specific session_close
1737  * callback.
1738  */
1739 void __l2tp_session_unhash(struct l2tp_session *session)
1740 {
1741         struct l2tp_tunnel *tunnel = session->tunnel;
1742
1743         /* Remove the session from core hashes */
1744         if (tunnel) {
1745                 /* Remove from the per-tunnel hash */
1746                 write_lock_bh(&tunnel->hlist_lock);
1747                 hlist_del_init(&session->hlist);
1748                 write_unlock_bh(&tunnel->hlist_lock);
1749
1750                 /* For L2TPv3 we have a per-net hash: remove from there, too */
1751                 if (tunnel->version != L2TP_HDR_VER_2) {
1752                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1753                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1754                         hlist_del_init_rcu(&session->global_hlist);
1755                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1756                         synchronize_rcu();
1757                 }
1758         }
1759 }
1760 EXPORT_SYMBOL_GPL(__l2tp_session_unhash);
1761
1762 /* This function is used by the netlink SESSION_DELETE command and by
1763    pseudowire modules.
1764  */
1765 int l2tp_session_delete(struct l2tp_session *session)
1766 {
1767         if (test_and_set_bit(0, &session->dead))
1768                 return 0;
1769
1770         if (session->ref)
1771                 (*session->ref)(session);
1772         __l2tp_session_unhash(session);
1773         l2tp_session_queue_purge(session);
1774         if (session->session_close != NULL)
1775                 (*session->session_close)(session);
1776         if (session->deref)
1777                 (*session->deref)(session);
1778         l2tp_session_dec_refcount(session);
1779         return 0;
1780 }
1781 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1782
1783 /* We come here whenever a session's send_seq, cookie_len or
1784  * l2specific_type parameters are set.
1785  */
1786 void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1787 {
1788         if (version == L2TP_HDR_VER_2) {
1789                 session->hdr_len = 6;
1790                 if (session->send_seq)
1791                         session->hdr_len += 4;
1792         } else {
1793                 session->hdr_len = 4 + session->cookie_len + session->offset;
1794                 session->hdr_len += l2tp_get_l2specific_len(session);
1795                 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1796                         session->hdr_len += 4;
1797         }
1798
1799 }
1800 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len);
1801
1802 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)
1803 {
1804         struct l2tp_session *session;
1805
1806         session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1807         if (session != NULL) {
1808                 session->magic = L2TP_SESSION_MAGIC;
1809                 session->tunnel = tunnel;
1810
1811                 session->session_id = session_id;
1812                 session->peer_session_id = peer_session_id;
1813                 session->nr = 0;
1814                 if (tunnel->version == L2TP_HDR_VER_2)
1815                         session->nr_max = 0xffff;
1816                 else
1817                         session->nr_max = 0xffffff;
1818                 session->nr_window_size = session->nr_max / 2;
1819                 session->nr_oos_count_max = 4;
1820
1821                 /* Use NR of first received packet */
1822                 session->reorder_skip = 1;
1823
1824                 sprintf(&session->name[0], "sess %u/%u",
1825                         tunnel->tunnel_id, session->session_id);
1826
1827                 skb_queue_head_init(&session->reorder_q);
1828
1829                 INIT_HLIST_NODE(&session->hlist);
1830                 INIT_HLIST_NODE(&session->global_hlist);
1831
1832                 /* Inherit debug options from tunnel */
1833                 session->debug = tunnel->debug;
1834
1835                 if (cfg) {
1836                         session->pwtype = cfg->pw_type;
1837                         session->debug = cfg->debug;
1838                         session->mtu = cfg->mtu;
1839                         session->mru = cfg->mru;
1840                         session->send_seq = cfg->send_seq;
1841                         session->recv_seq = cfg->recv_seq;
1842                         session->lns_mode = cfg->lns_mode;
1843                         session->reorder_timeout = cfg->reorder_timeout;
1844                         session->offset = cfg->offset;
1845                         session->l2specific_type = cfg->l2specific_type;
1846                         session->l2specific_len = cfg->l2specific_len;
1847                         session->cookie_len = cfg->cookie_len;
1848                         memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1849                         session->peer_cookie_len = cfg->peer_cookie_len;
1850                         memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1851                 }
1852
1853                 if (tunnel->version == L2TP_HDR_VER_2)
1854                         session->build_header = l2tp_build_l2tpv2_header;
1855                 else
1856                         session->build_header = l2tp_build_l2tpv3_header;
1857
1858                 l2tp_session_set_header_len(session, tunnel->version);
1859
1860                 l2tp_session_inc_refcount(session);
1861
1862                 return session;
1863         }
1864
1865         return ERR_PTR(-ENOMEM);
1866 }
1867 EXPORT_SYMBOL_GPL(l2tp_session_create);
1868
1869 /*****************************************************************************
1870  * Init and cleanup
1871  *****************************************************************************/
1872
1873 static __net_init int l2tp_init_net(struct net *net)
1874 {
1875         struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1876         int hash;
1877
1878         INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1879         spin_lock_init(&pn->l2tp_tunnel_list_lock);
1880
1881         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1882                 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1883
1884         spin_lock_init(&pn->l2tp_session_hlist_lock);
1885
1886         return 0;
1887 }
1888
1889 static __net_exit void l2tp_exit_net(struct net *net)
1890 {
1891         struct l2tp_net *pn = l2tp_pernet(net);
1892         struct l2tp_tunnel *tunnel = NULL;
1893
1894         rcu_read_lock_bh();
1895         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
1896                 l2tp_tunnel_delete(tunnel);
1897         }
1898         rcu_read_unlock_bh();
1899
1900         flush_workqueue(l2tp_wq);
1901         rcu_barrier();
1902 }
1903
1904 static struct pernet_operations l2tp_net_ops = {
1905         .init = l2tp_init_net,
1906         .exit = l2tp_exit_net,
1907         .id   = &l2tp_net_id,
1908         .size = sizeof(struct l2tp_net),
1909 };
1910
1911 static int __init l2tp_init(void)
1912 {
1913         int rc = 0;
1914
1915         rc = register_pernet_device(&l2tp_net_ops);
1916         if (rc)
1917                 goto out;
1918
1919         l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0);
1920         if (!l2tp_wq) {
1921                 pr_err("alloc_workqueue failed\n");
1922                 unregister_pernet_device(&l2tp_net_ops);
1923                 rc = -ENOMEM;
1924                 goto out;
1925         }
1926
1927         pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
1928
1929 out:
1930         return rc;
1931 }
1932
1933 static void __exit l2tp_exit(void)
1934 {
1935         unregister_pernet_device(&l2tp_net_ops);
1936         if (l2tp_wq) {
1937                 destroy_workqueue(l2tp_wq);
1938                 l2tp_wq = NULL;
1939         }
1940 }
1941
1942 module_init(l2tp_init);
1943 module_exit(l2tp_exit);
1944
1945 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1946 MODULE_DESCRIPTION("L2TP core");
1947 MODULE_LICENSE("GPL");
1948 MODULE_VERSION(L2TP_DRV_VERSION);
1949