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/inet_common.h>
  56 #include <net/xfrm.h>
  57 #include <net/protocol.h>
  58 #include <net/inet6_connection_sock.h>
  59 #include <net/inet_ecn.h>
  60 #include <net/ip6_route.h>
  61 #include <net/ip6_checksum.h>
  62
  63 #include <asm/byteorder.h>
  64 #include <linux/atomic.h>
  65
  66 #include "l2tp_core.h"
  67
  68 #define L2TP_DRV_VERSION        "V2.0"
  69
  70 /* L2TP header constants */
  71 #define L2TP_HDRFLAG_T     0x8000
  72 #define L2TP_HDRFLAG_L     0x4000
  73 #define L2TP_HDRFLAG_S     0x0800
  74 #define L2TP_HDRFLAG_O     0x0200
  75 #define L2TP_HDRFLAG_P     0x0100
  76
  77 #define L2TP_HDR_VER_MASK  0x000F
  78 #define L2TP_HDR_VER_2     0x0002
  79 #define L2TP_HDR_VER_3     0x0003
  80
  81 /* L2TPv3 default L2-specific sublayer */
  82 #define L2TP_SLFLAG_S      0x40000000
  83 #define L2TP_SL_SEQ_MASK   0x00ffffff
  84
  85 #define L2TP_HDR_SIZE_SEQ               10
  86 #define L2TP_HDR_SIZE_NOSEQ             6
  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
 105 /* per-net private data for this module */
 106 static unsigned int l2tp_net_id;
 107 struct l2tp_net {
 108         struct list_head l2tp_tunnel_list;
 109         spinlock_t l2tp_tunnel_list_lock;
 110         struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
 111         spinlock_t l2tp_session_hlist_lock;
 112 };
 113
 114 static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 115 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
 116 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
 117
 118 static inline struct l2tp_net *l2tp_pernet(struct net *net)
 119 {
 120         BUG_ON(!net);
 121
 122         return net_generic(net, l2tp_net_id);
 123 }
 124
 125
 126 /* Tunnel reference counts. Incremented per session that is added to
 127  * the tunnel.
 128  */
 129 static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
 130 {
 131         atomic_inc(&tunnel->ref_count);
 132 }
 133
 134 static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
 135 {
 136         if (atomic_dec_and_test(&tunnel->ref_count))
 137                 l2tp_tunnel_free(tunnel);
 138 }
 139 #ifdef L2TP_REFCNT_DEBUG
 140 #define l2tp_tunnel_inc_refcount(_t)                                    \
 141 do {                                                                    \
 142         pr_debug("l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n",        \
 143                  __func__, __LINE__, (_t)->name,                        \
 144                  atomic_read(&_t->ref_count));                          \
 145         l2tp_tunnel_inc_refcount_1(_t);                                 \
 146 } while (0)
 147 #define l2tp_tunnel_dec_refcount(_t)
 148 do {                                                                    \
 149         pr_debug("l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n",        \
 150                  __func__, __LINE__, (_t)->name,                        \
 151                  atomic_read(&_t->ref_count));                          \
 152         l2tp_tunnel_dec_refcount_1(_t);                                 \
 153 } while (0)
 154 #else
 155 #define l2tp_tunnel_inc_refcount(t) l2tp_tunnel_inc_refcount_1(t)
 156 #define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t)
 157 #endif
 158
 159 /* Session hash global list for L2TPv3.
 160  * The session_id SHOULD be random according to RFC3931, but several
 161  * L2TP implementations use incrementing session_ids.  So we do a real
 162  * hash on the session_id, rather than a simple bitmask.
 163  */
 164 static inline struct hlist_head *
 165 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
 166 {
 167         return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
 168
 169 }
 170
 171 /* Lookup the tunnel socket, possibly involving the fs code if the socket is
 172  * owned by userspace.  A struct sock returned from this function must be
 173  * released using l2tp_tunnel_sock_put once you're done with it.
 174  */
 175 struct sock *l2tp_tunnel_sock_lookup(struct l2tp_tunnel *tunnel)
 176 {
 177         int err = 0;
 178         struct socket *sock = NULL;
 179         struct sock *sk = NULL;
 180
 181         if (!tunnel)
 182                 goto out;
 183
 184         if (tunnel->fd >= 0) {
 185                 /* Socket is owned by userspace, who might be in the process
 186                  * of closing it.  Look the socket up using the fd to ensure
 187                  * consistency.
 188                  */
 189                 sock = sockfd_lookup(tunnel->fd, &err);
 190                 if (sock)
 191                         sk = sock->sk;
 192         } else {
 193                 /* Socket is owned by kernelspace */
 194                 sk = tunnel->sock;
 195         }
 196
 197 out:
 198         return sk;
 199 }
 200 EXPORT_SYMBOL_GPL(l2tp_tunnel_sock_lookup);
 201
 202 /* Drop a reference to a tunnel socket obtained via. l2tp_tunnel_sock_put */
 203 void l2tp_tunnel_sock_put(struct sock *sk)
 204 {
 205         struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
 206         if (tunnel) {
 207                 if (tunnel->fd >= 0) {
 208                         /* Socket is owned by userspace */
 209                         sockfd_put(sk->sk_socket);
 210                 }
 211                 sock_put(sk);
 212         }
 213 }
 214 EXPORT_SYMBOL_GPL(l2tp_tunnel_sock_put);
 215
 216 /* Lookup a session by id in the global session list
 217  */
 218 static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
 219 {
 220         struct l2tp_net *pn = l2tp_pernet(net);
 221         struct hlist_head *session_list =
 222                 l2tp_session_id_hash_2(pn, session_id);
 223         struct l2tp_session *session;
 224         struct hlist_node *walk;
 225
 226         rcu_read_lock_bh();
 227         hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) {
 228                 if (session->session_id == session_id) {
 229                         rcu_read_unlock_bh();
 230                         return session;
 231                 }
 232         }
 233         rcu_read_unlock_bh();
 234
 235         return NULL;
 236 }
 237
 238 /* Session hash list.
 239  * The session_id SHOULD be random according to RFC2661, but several
 240  * L2TP implementations (Cisco and Microsoft) use incrementing
 241  * session_ids.  So we do a real hash on the session_id, rather than a
 242  * simple bitmask.
 243  */
 244 static inline struct hlist_head *
 245 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
 246 {
 247         return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
 248 }
 249
 250 /* Lookup a session by id
 251  */
 252 struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
 253 {
 254         struct hlist_head *session_list;
 255         struct l2tp_session *session;
 256         struct hlist_node *walk;
 257
 258         /* In L2TPv3, session_ids are unique over all tunnels and we
 259          * sometimes need to look them up before we know the
 260          * tunnel.
 261          */
 262         if (tunnel == NULL)
 263                 return l2tp_session_find_2(net, session_id);
 264
 265         session_list = l2tp_session_id_hash(tunnel, session_id);
 266         read_lock_bh(&tunnel->hlist_lock);
 267         hlist_for_each_entry(session, walk, session_list, hlist) {
 268                 if (session->session_id == session_id) {
 269                         read_unlock_bh(&tunnel->hlist_lock);
 270                         return session;
 271                 }
 272         }
 273         read_unlock_bh(&tunnel->hlist_lock);
 274
 275         return NULL;
 276 }
 277 EXPORT_SYMBOL_GPL(l2tp_session_find);
 278
 279 struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
 280 {
 281         int hash;
 282         struct hlist_node *walk;
 283         struct l2tp_session *session;
 284         int count = 0;
 285
 286         read_lock_bh(&tunnel->hlist_lock);
 287         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
 288                 hlist_for_each_entry(session, walk, &tunnel->session_hlist[hash], hlist) {
 289                         if (++count > nth) {
 290                                 read_unlock_bh(&tunnel->hlist_lock);
 291                                 return session;
 292                         }
 293                 }
 294         }
 295
 296         read_unlock_bh(&tunnel->hlist_lock);
 297
 298         return NULL;
 299 }
 300 EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
 301
 302 /* Lookup a session by interface name.
 303  * This is very inefficient but is only used by management interfaces.
 304  */
 305 struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
 306 {
 307         struct l2tp_net *pn = l2tp_pernet(net);
 308         int hash;
 309         struct hlist_node *walk;
 310         struct l2tp_session *session;
 311
 312         rcu_read_lock_bh();
 313         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
 314                 hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
 315                         if (!strcmp(session->ifname, ifname)) {
 316                                 rcu_read_unlock_bh();
 317                                 return session;
 318                         }
 319                 }
 320         }
 321
 322         rcu_read_unlock_bh();
 323
 324         return NULL;
 325 }
 326 EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
 327
 328 /* Lookup a tunnel by id
 329  */
 330 struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
 331 {
 332         struct l2tp_tunnel *tunnel;
 333         struct l2tp_net *pn = l2tp_pernet(net);
 334
 335         rcu_read_lock_bh();
 336         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 337                 if (tunnel->tunnel_id == tunnel_id) {
 338                         rcu_read_unlock_bh();
 339                         return tunnel;
 340                 }
 341         }
 342         rcu_read_unlock_bh();
 343
 344         return NULL;
 345 }
 346 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
 347
 348 struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
 349 {
 350         struct l2tp_net *pn = l2tp_pernet(net);
 351         struct l2tp_tunnel *tunnel;
 352         int count = 0;
 353
 354         rcu_read_lock_bh();
 355         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 356                 if (++count > nth) {
 357                         rcu_read_unlock_bh();
 358                         return tunnel;
 359                 }
 360         }
 361
 362         rcu_read_unlock_bh();
 363
 364         return NULL;
 365 }
 366 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
 367
 368 /*****************************************************************************
 369  * Receive data handling
 370  *****************************************************************************/
 371
 372 /* Queue a skb in order. We come here only if the skb has an L2TP sequence
 373  * number.
 374  */
 375 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
 376 {
 377         struct sk_buff *skbp;
 378         struct sk_buff *tmp;
 379         u32 ns = L2TP_SKB_CB(skb)->ns;
 380         struct l2tp_stats *sstats;
 381
 382         spin_lock_bh(&session->reorder_q.lock);
 383         sstats = &session->stats;
 384         skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
 385                 if (L2TP_SKB_CB(skbp)->ns > ns) {
 386                         __skb_queue_before(&session->reorder_q, skbp, skb);
 387                         l2tp_dbg(session, L2TP_MSG_SEQ,
 388                                  "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
 389                                  session->name, ns, L2TP_SKB_CB(skbp)->ns,
 390                                  skb_queue_len(&session->reorder_q));
 391                         u64_stats_update_begin(&sstats->syncp);
 392                         sstats->rx_oos_packets++;
 393                         u64_stats_update_end(&sstats->syncp);
 394                         goto out;
 395                 }
 396         }
 397
 398         __skb_queue_tail(&session->reorder_q, skb);
 399
 400 out:
 401         spin_unlock_bh(&session->reorder_q.lock);
 402 }
 403
 404 /* Dequeue a single skb.
 405  */
 406 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
 407 {
 408         struct l2tp_tunnel *tunnel = session->tunnel;
 409         int length = L2TP_SKB_CB(skb)->length;
 410         struct l2tp_stats *tstats, *sstats;
 411
 412         /* We're about to requeue the skb, so return resources
 413          * to its current owner (a socket receive buffer).
 414          */
 415         skb_orphan(skb);
 416
 417         tstats = &tunnel->stats;
 418         u64_stats_update_begin(&tstats->syncp);
 419         sstats = &session->stats;
 420         u64_stats_update_begin(&sstats->syncp);
 421         tstats->rx_packets++;
 422         tstats->rx_bytes += length;
 423         sstats->rx_packets++;
 424         sstats->rx_bytes += length;
 425         u64_stats_update_end(&tstats->syncp);
 426         u64_stats_update_end(&sstats->syncp);
 427
 428         if (L2TP_SKB_CB(skb)->has_seq) {
 429                 /* Bump our Nr */
 430                 session->nr++;
 431                 if (tunnel->version == L2TP_HDR_VER_2)
 432                         session->nr &= 0xffff;
 433                 else
 434                         session->nr &= 0xffffff;
 435
 436                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
 437                          session->name, session->nr);
 438         }
 439
 440         /* call private receive handler */
 441         if (session->recv_skb != NULL)
 442                 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
 443         else
 444                 kfree_skb(skb);
 445
 446         if (session->deref)
 447                 (*session->deref)(session);
 448 }
 449
 450 /* Dequeue skbs from the session's reorder_q, subject to packet order.
 451  * Skbs that have been in the queue for too long are simply discarded.
 452  */
 453 static void l2tp_recv_dequeue(struct l2tp_session *session)
 454 {
 455         struct sk_buff *skb;
 456         struct sk_buff *tmp;
 457         struct l2tp_stats *sstats;
 458
 459         /* If the pkt at the head of the queue has the nr that we
 460          * expect to send up next, dequeue it and any other
 461          * in-sequence packets behind it.
 462          */
 463 start:
 464         spin_lock_bh(&session->reorder_q.lock);
 465         sstats = &session->stats;
 466         skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
 467                 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
 468                         u64_stats_update_begin(&sstats->syncp);
 469                         sstats->rx_seq_discards++;
 470                         sstats->rx_errors++;
 471                         u64_stats_update_end(&sstats->syncp);
 472                         l2tp_dbg(session, L2TP_MSG_SEQ,
 473                                  "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
 474                                  session->name, L2TP_SKB_CB(skb)->ns,
 475                                  L2TP_SKB_CB(skb)->length, session->nr,
 476                                  skb_queue_len(&session->reorder_q));
 477                         session->reorder_skip = 1;
 478                         __skb_unlink(skb, &session->reorder_q);
 479                         kfree_skb(skb);
 480                         if (session->deref)
 481                                 (*session->deref)(session);
 482                         continue;
 483                 }
 484
 485                 if (L2TP_SKB_CB(skb)->has_seq) {
 486                         if (session->reorder_skip) {
 487                                 l2tp_dbg(session, L2TP_MSG_SEQ,
 488                                          "%s: advancing nr to next pkt: %u -> %u",
 489                                          session->name, session->nr,
 490                                          L2TP_SKB_CB(skb)->ns);
 491                                 session->reorder_skip = 0;
 492                                 session->nr = L2TP_SKB_CB(skb)->ns;
 493                         }
 494                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
 495                                 l2tp_dbg(session, L2TP_MSG_SEQ,
 496                                          "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
 497                                          session->name, L2TP_SKB_CB(skb)->ns,
 498                                          L2TP_SKB_CB(skb)->length, session->nr,
 499                                          skb_queue_len(&session->reorder_q));
 500                                 goto out;
 501                         }
 502                 }
 503                 __skb_unlink(skb, &session->reorder_q);
 504
 505                 /* Process the skb. We release the queue lock while we
 506                  * do so to let other contexts process the queue.
 507                  */
 508                 spin_unlock_bh(&session->reorder_q.lock);
 509                 l2tp_recv_dequeue_skb(session, skb);
 510                 goto start;
 511         }
 512
 513 out:
 514         spin_unlock_bh(&session->reorder_q.lock);
 515 }
 516
 517 static inline int l2tp_verify_udp_checksum(struct sock *sk,
 518                                            struct sk_buff *skb)
 519 {
 520         struct udphdr *uh = udp_hdr(skb);
 521         u16 ulen = ntohs(uh->len);
 522         __wsum psum;
 523
 524         if (sk->sk_no_check || skb_csum_unnecessary(skb))
 525                 return 0;
 526
 527 #if IS_ENABLED(CONFIG_IPV6)
 528         if (sk->sk_family == PF_INET6) {
 529                 if (!uh->check) {
 530                         LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n");
 531                         return 1;
 532                 }
 533                 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
 534                     !csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
 535                                      &ipv6_hdr(skb)->daddr, ulen,
 536                                      IPPROTO_UDP, skb->csum)) {
 537                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 538                         return 0;
 539                 }
 540                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
 541                                                          &ipv6_hdr(skb)->daddr,
 542                                                          skb->len, IPPROTO_UDP,
 543                                                          0));
 544         } else
 545 #endif
 546         {
 547                 struct inet_sock *inet;
 548                 if (!uh->check)
 549                         return 0;
 550                 inet = inet_sk(sk);
 551                 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr,
 552                                           ulen, IPPROTO_UDP, 0);
 553
 554                 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
 555                     !csum_fold(csum_add(psum, skb->csum)))
 556                         return 0;
 557                 skb->csum = psum;
 558         }
 559
 560         return __skb_checksum_complete(skb);
 561 }
 562
 563 /* Do receive processing of L2TP data frames. We handle both L2TPv2
 564  * and L2TPv3 data frames here.
 565  *
 566  * L2TPv2 Data Message Header
 567  *
 568  *  0                   1                   2                   3
 569  *  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
 570  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 571  * |T|L|x|x|S|x|O|P|x|x|x|x|  Ver  |          Length (opt)         |
 572  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 573  * |           Tunnel ID           |           Session ID          |
 574  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 575  * |             Ns (opt)          |             Nr (opt)          |
 576  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 577  * |      Offset Size (opt)        |    Offset pad... (opt)
 578  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 579  *
 580  * Data frames are marked by T=0. All other fields are the same as
 581  * those in L2TP control frames.
 582  *
 583  * L2TPv3 Data Message Header
 584  *
 585  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 586  * |                      L2TP Session Header                      |
 587  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 588  * |                      L2-Specific Sublayer                     |
 589  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 590  * |                        Tunnel Payload                      ...
 591  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 592  *
 593  * L2TPv3 Session Header Over IP
 594  *
 595  *  0                   1                   2                   3
 596  *  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
 597  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 598  * |                           Session ID                          |
 599  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 600  * |               Cookie (optional, maximum 64 bits)...
 601  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 602  *                                                                 |
 603  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 604  *
 605  * L2TPv3 L2-Specific Sublayer Format
 606  *
 607  *  0                   1                   2                   3
 608  *  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
 609  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 610  * |x|S|x|x|x|x|x|x|              Sequence Number                  |
 611  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 612  *
 613  * Cookie value, sublayer format and offset (pad) are negotiated with
 614  * the peer when the session is set up. Unlike L2TPv2, we do not need
 615  * to parse the packet header to determine if optional fields are
 616  * present.
 617  *
 618  * Caller must already have parsed the frame and determined that it is
 619  * a data (not control) frame before coming here. Fields up to the
 620  * session-id have already been parsed and ptr points to the data
 621  * after the session-id.
 622  */
 623 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 624                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 625                       int length, int (*payload_hook)(struct sk_buff *skb))
 626 {
 627         struct l2tp_tunnel *tunnel = session->tunnel;
 628         int offset;
 629         u32 ns, nr;
 630         struct l2tp_stats *sstats = &session->stats;
 631
 632         /* The ref count is increased since we now hold a pointer to
 633          * the session. Take care to decrement the refcnt when exiting
 634          * this function from now on...
 635          */
 636         l2tp_session_inc_refcount(session);
 637         if (session->ref)
 638                 (*session->ref)(session);
 639
 640         /* Parse and check optional cookie */
 641         if (session->peer_cookie_len > 0) {
 642                 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
 643                         l2tp_info(tunnel, L2TP_MSG_DATA,
 644                                   "%s: cookie mismatch (%u/%u). Discarding.\n",
 645                                   tunnel->name, tunnel->tunnel_id,
 646                                   session->session_id);
 647                         u64_stats_update_begin(&sstats->syncp);
 648                         sstats->rx_cookie_discards++;
 649                         u64_stats_update_end(&sstats->syncp);
 650                         goto discard;
 651                 }
 652                 ptr += session->peer_cookie_len;
 653         }
 654
 655         /* Handle the optional sequence numbers. Sequence numbers are
 656          * in different places for L2TPv2 and L2TPv3.
 657          *
 658          * If we are the LAC, enable/disable sequence numbers under
 659          * the control of the LNS.  If no sequence numbers present but
 660          * we were expecting them, discard frame.
 661          */
 662         ns = nr = 0;
 663         L2TP_SKB_CB(skb)->has_seq = 0;
 664         if (tunnel->version == L2TP_HDR_VER_2) {
 665                 if (hdrflags & L2TP_HDRFLAG_S) {
 666                         ns = ntohs(*(__be16 *) ptr);
 667                         ptr += 2;
 668                         nr = ntohs(*(__be16 *) ptr);
 669                         ptr += 2;
 670
 671                         /* Store L2TP info in the skb */
 672                         L2TP_SKB_CB(skb)->ns = ns;
 673                         L2TP_SKB_CB(skb)->has_seq = 1;
 674
 675                         l2tp_dbg(session, L2TP_MSG_SEQ,
 676                                  "%s: recv data ns=%u, nr=%u, session nr=%u\n",
 677                                  session->name, ns, nr, session->nr);
 678                 }
 679         } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
 680                 u32 l2h = ntohl(*(__be32 *) ptr);
 681
 682                 if (l2h & 0x40000000) {
 683                         ns = l2h & 0x00ffffff;
 684
 685                         /* Store L2TP info in the skb */
 686                         L2TP_SKB_CB(skb)->ns = ns;
 687                         L2TP_SKB_CB(skb)->has_seq = 1;
 688
 689                         l2tp_dbg(session, L2TP_MSG_SEQ,
 690                                  "%s: recv data ns=%u, session nr=%u\n",
 691                                  session->name, ns, session->nr);
 692                 }
 693         }
 694
 695         /* Advance past L2-specific header, if present */
 696         ptr += session->l2specific_len;
 697
 698         if (L2TP_SKB_CB(skb)->has_seq) {
 699                 /* Received a packet with sequence numbers. If we're the LNS,
 700                  * check if we sre sending sequence numbers and if not,
 701                  * configure it so.
 702                  */
 703                 if ((!session->lns_mode) && (!session->send_seq)) {
 704                         l2tp_info(session, L2TP_MSG_SEQ,
 705                                   "%s: requested to enable seq numbers by LNS\n",
 706                                   session->name);
 707                         session->send_seq = -1;
 708                         l2tp_session_set_header_len(session, tunnel->version);
 709                 }
 710         } else {
 711                 /* No sequence numbers.
 712                  * If user has configured mandatory sequence numbers, discard.
 713                  */
 714                 if (session->recv_seq) {
 715                         l2tp_warn(session, L2TP_MSG_SEQ,
 716                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 717                                   session->name);
 718                         u64_stats_update_begin(&sstats->syncp);
 719                         sstats->rx_seq_discards++;
 720                         u64_stats_update_end(&sstats->syncp);
 721                         goto discard;
 722                 }
 723
 724                 /* If we're the LAC and we're sending sequence numbers, the
 725                  * LNS has requested that we no longer send sequence numbers.
 726                  * If we're the LNS and we're sending sequence numbers, the
 727                  * LAC is broken. Discard the frame.
 728                  */
 729                 if ((!session->lns_mode) && (session->send_seq)) {
 730                         l2tp_info(session, L2TP_MSG_SEQ,
 731                                   "%s: requested to disable seq numbers by LNS\n",
 732                                   session->name);
 733                         session->send_seq = 0;
 734                         l2tp_session_set_header_len(session, tunnel->version);
 735                 } else if (session->send_seq) {
 736                         l2tp_warn(session, L2TP_MSG_SEQ,
 737                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 738                                   session->name);
 739                         u64_stats_update_begin(&sstats->syncp);
 740                         sstats->rx_seq_discards++;
 741                         u64_stats_update_end(&sstats->syncp);
 742                         goto discard;
 743                 }
 744         }
 745
 746         /* Session data offset is handled differently for L2TPv2 and
 747          * L2TPv3. For L2TPv2, there is an optional 16-bit value in
 748          * the header. For L2TPv3, the offset is negotiated using AVPs
 749          * in the session setup control protocol.
 750          */
 751         if (tunnel->version == L2TP_HDR_VER_2) {
 752                 /* If offset bit set, skip it. */
 753                 if (hdrflags & L2TP_HDRFLAG_O) {
 754                         offset = ntohs(*(__be16 *)ptr);
 755                         ptr += 2 + offset;
 756                 }
 757         } else
 758                 ptr += session->offset;
 759
 760         offset = ptr - optr;
 761         if (!pskb_may_pull(skb, offset))
 762                 goto discard;
 763
 764         __skb_pull(skb, offset);
 765
 766         /* If caller wants to process the payload before we queue the
 767          * packet, do so now.
 768          */
 769         if (payload_hook)
 770                 if ((*payload_hook)(skb))
 771                         goto discard;
 772
 773         /* Prepare skb for adding to the session's reorder_q.  Hold
 774          * packets for max reorder_timeout or 1 second if not
 775          * reordering.
 776          */
 777         L2TP_SKB_CB(skb)->length = length;
 778         L2TP_SKB_CB(skb)->expires = jiffies +
 779                 (session->reorder_timeout ? session->reorder_timeout : HZ);
 780
 781         /* Add packet to the session's receive queue. Reordering is done here, if
 782          * enabled. Saved L2TP protocol info is stored in skb->sb[].
 783          */
 784         if (L2TP_SKB_CB(skb)->has_seq) {
 785                 if (session->reorder_timeout != 0) {
 786                         /* Packet reordering enabled. Add skb to session's
 787                          * reorder queue, in order of ns.
 788                          */
 789                         l2tp_recv_queue_skb(session, skb);
 790                 } else {
 791                         /* Packet reordering disabled. Discard out-of-sequence
 792                          * packets
 793                          */
 794                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
 795                                 u64_stats_update_begin(&sstats->syncp);
 796                                 sstats->rx_seq_discards++;
 797                                 u64_stats_update_end(&sstats->syncp);
 798                                 l2tp_dbg(session, L2TP_MSG_SEQ,
 799                                          "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
 800                                          session->name, L2TP_SKB_CB(skb)->ns,
 801                                          L2TP_SKB_CB(skb)->length, session->nr,
 802                                          skb_queue_len(&session->reorder_q));
 803                                 goto discard;
 804                         }
 805                         skb_queue_tail(&session->reorder_q, skb);
 806                 }
 807         } else {
 808                 /* No sequence numbers. Add the skb to the tail of the
 809                  * reorder queue. This ensures that it will be
 810                  * delivered after all previous sequenced skbs.
 811                  */
 812                 skb_queue_tail(&session->reorder_q, skb);
 813         }
 814
 815         /* Try to dequeue as many skbs from reorder_q as we can. */
 816         l2tp_recv_dequeue(session);
 817
 818         l2tp_session_dec_refcount(session);
 819
 820         return;
 821
 822 discard:
 823         u64_stats_update_begin(&sstats->syncp);
 824         sstats->rx_errors++;
 825         u64_stats_update_end(&sstats->syncp);
 826         kfree_skb(skb);
 827
 828         if (session->deref)
 829                 (*session->deref)(session);
 830
 831         l2tp_session_dec_refcount(session);
 832 }
 833 EXPORT_SYMBOL(l2tp_recv_common);
 834
 835 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
 836  * here. The skb is not on a list when we get here.
 837  * Returns 0 if the packet was a data packet and was successfully passed on.
 838  * Returns 1 if the packet was not a good data packet and could not be
 839  * forwarded.  All such packets are passed up to userspace to deal with.
 840  */
 841 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
 842                               int (*payload_hook)(struct sk_buff *skb))
 843 {
 844         struct l2tp_session *session = NULL;
 845         unsigned char *ptr, *optr;
 846         u16 hdrflags;
 847         u32 tunnel_id, session_id;
 848         u16 version;
 849         int length;
 850         struct l2tp_stats *tstats;
 851
 852         if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
 853                 goto discard_bad_csum;
 854
 855         /* UDP always verifies the packet length. */
 856         __skb_pull(skb, sizeof(struct udphdr));
 857
 858         /* Short packet? */
 859         if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
 860                 l2tp_info(tunnel, L2TP_MSG_DATA,
 861                           "%s: recv short packet (len=%d)\n",
 862                           tunnel->name, skb->len);
 863                 goto error;
 864         }
 865
 866         /* Trace packet contents, if enabled */
 867         if (tunnel->debug & L2TP_MSG_DATA) {
 868                 length = min(32u, skb->len);
 869                 if (!pskb_may_pull(skb, length))
 870                         goto error;
 871
 872                 pr_debug("%s: recv\n", tunnel->name);
 873                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
 874         }
 875
 876         /* Point to L2TP header */
 877         optr = ptr = skb->data;
 878
 879         /* Get L2TP header flags */
 880         hdrflags = ntohs(*(__be16 *) ptr);
 881
 882         /* Check protocol version */
 883         version = hdrflags & L2TP_HDR_VER_MASK;
 884         if (version != tunnel->version) {
 885                 l2tp_info(tunnel, L2TP_MSG_DATA,
 886                           "%s: recv protocol version mismatch: got %d expected %d\n",
 887                           tunnel->name, version, tunnel->version);
 888                 goto error;
 889         }
 890
 891         /* Get length of L2TP packet */
 892         length = skb->len;
 893
 894         /* If type is control packet, it is handled by userspace. */
 895         if (hdrflags & L2TP_HDRFLAG_T) {
 896                 l2tp_dbg(tunnel, L2TP_MSG_DATA,
 897                          "%s: recv control packet, len=%d\n",
 898                          tunnel->name, length);
 899                 goto error;
 900         }
 901
 902         /* Skip flags */
 903         ptr += 2;
 904
 905         if (tunnel->version == L2TP_HDR_VER_2) {
 906                 /* If length is present, skip it */
 907                 if (hdrflags & L2TP_HDRFLAG_L)
 908                         ptr += 2;
 909
 910                 /* Extract tunnel and session ID */
 911                 tunnel_id = ntohs(*(__be16 *) ptr);
 912                 ptr += 2;
 913                 session_id = ntohs(*(__be16 *) ptr);
 914                 ptr += 2;
 915         } else {
 916                 ptr += 2;       /* skip reserved bits */
 917                 tunnel_id = tunnel->tunnel_id;
 918                 session_id = ntohl(*(__be32 *) ptr);
 919                 ptr += 4;
 920         }
 921
 922         /* Find the session context */
 923         session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
 924         if (!session || !session->recv_skb) {
 925                 /* Not found? Pass to userspace to deal with */
 926                 l2tp_info(tunnel, L2TP_MSG_DATA,
 927                           "%s: no session found (%u/%u). Passing up.\n",
 928                           tunnel->name, tunnel_id, session_id);
 929                 goto error;
 930         }
 931
 932         l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
 933
 934         return 0;
 935
 936 discard_bad_csum:
 937         LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
 938         UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
 939         tstats = &tunnel->stats;
 940         u64_stats_update_begin(&tstats->syncp);
 941         tstats->rx_errors++;
 942         u64_stats_update_end(&tstats->syncp);
 943         kfree_skb(skb);
 944
 945         return 0;
 946
 947 error:
 948         /* Put UDP header back */
 949         __skb_push(skb, sizeof(struct udphdr));
 950
 951         return 1;
 952 }
 953
 954 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
 955  * Return codes:
 956  * 0 : success.
 957  * <0: error
 958  * >0: skb should be passed up to userspace as UDP.
 959  */
 960 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 961 {
 962         struct l2tp_tunnel *tunnel;
 963
 964         tunnel = l2tp_sock_to_tunnel(sk);
 965         if (tunnel == NULL)
 966                 goto pass_up;
 967
 968         l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
 969                  tunnel->name, skb->len);
 970
 971         if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
 972                 goto pass_up_put;
 973
 974         sock_put(sk);
 975         return 0;
 976
 977 pass_up_put:
 978         sock_put(sk);
 979 pass_up:
 980         return 1;
 981 }
 982 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
 983
 984 /************************************************************************
 985  * Transmit handling
 986  ***********************************************************************/
 987
 988 /* Build an L2TP header for the session into the buffer provided.
 989  */
 990 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
 991 {
 992         struct l2tp_tunnel *tunnel = session->tunnel;
 993         __be16 *bufp = buf;
 994         __be16 *optr = buf;
 995         u16 flags = L2TP_HDR_VER_2;
 996         u32 tunnel_id = tunnel->peer_tunnel_id;
 997         u32 session_id = session->peer_session_id;
 998
 999         if (session->send_seq)
1000                 flags |= L2TP_HDRFLAG_S;
1001
1002         /* Setup L2TP header. */
1003         *bufp++ = htons(flags);
1004         *bufp++ = htons(tunnel_id);
1005         *bufp++ = htons(session_id);
1006         if (session->send_seq) {
1007                 *bufp++ = htons(session->ns);
1008                 *bufp++ = 0;
1009                 session->ns++;
1010                 session->ns &= 0xffff;
1011                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
1012                          session->name, session->ns);
1013         }
1014
1015         return bufp - optr;
1016 }
1017
1018 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
1019 {
1020         struct l2tp_tunnel *tunnel = session->tunnel;
1021         char *bufp = buf;
1022         char *optr = bufp;
1023
1024         /* Setup L2TP header. The header differs slightly for UDP and
1025          * IP encapsulations. For UDP, there is 4 bytes of flags.
1026          */
1027         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
1028                 u16 flags = L2TP_HDR_VER_3;
1029                 *((__be16 *) bufp) = htons(flags);
1030                 bufp += 2;
1031                 *((__be16 *) bufp) = 0;
1032                 bufp += 2;
1033         }
1034
1035         *((__be32 *) bufp) = htonl(session->peer_session_id);
1036         bufp += 4;
1037         if (session->cookie_len) {
1038                 memcpy(bufp, &session->cookie[0], session->cookie_len);
1039                 bufp += session->cookie_len;
1040         }
1041         if (session->l2specific_len) {
1042                 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
1043                         u32 l2h = 0;
1044                         if (session->send_seq) {
1045                                 l2h = 0x40000000 | session->ns;
1046                                 session->ns++;
1047                                 session->ns &= 0xffffff;
1048                                 l2tp_dbg(session, L2TP_MSG_SEQ,
1049                                          "%s: updated ns to %u\n",
1050                                          session->name, session->ns);
1051                         }
1052
1053                         *((__be32 *) bufp) = htonl(l2h);
1054                 }
1055                 bufp += session->l2specific_len;
1056         }
1057         if (session->offset)
1058                 bufp += session->offset;
1059
1060         return bufp - optr;
1061 }
1062
1063 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1064                           struct flowi *fl, size_t data_len)
1065 {
1066         struct l2tp_tunnel *tunnel = session->tunnel;
1067         unsigned int len = skb->len;
1068         int error;
1069         struct l2tp_stats *tstats, *sstats;
1070
1071         /* Debug */
1072         if (session->send_seq)
1073                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n",
1074                          session->name, data_len, session->ns - 1);
1075         else
1076                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n",
1077                          session->name, data_len);
1078
1079         if (session->debug & L2TP_MSG_DATA) {
1080                 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1081                 unsigned char *datap = skb->data + uhlen;
1082
1083                 pr_debug("%s: xmit\n", session->name);
1084                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1085                                      datap, min_t(size_t, 32, len - uhlen));
1086         }
1087
1088         /* Queue the packet to IP for output */
1089         skb->local_df = 1;
1090 #if IS_ENABLED(CONFIG_IPV6)
1091         if (skb->sk->sk_family == PF_INET6)
1092                 error = inet6_csk_xmit(skb, NULL);
1093         else
1094 #endif
1095                 error = ip_queue_xmit(skb, fl);
1096
1097         /* Update stats */
1098         tstats = &tunnel->stats;
1099         u64_stats_update_begin(&tstats->syncp);
1100         sstats = &session->stats;
1101         u64_stats_update_begin(&sstats->syncp);
1102         if (error >= 0) {
1103                 tstats->tx_packets++;
1104                 tstats->tx_bytes += len;
1105                 sstats->tx_packets++;
1106                 sstats->tx_bytes += len;
1107         } else {
1108                 tstats->tx_errors++;
1109                 sstats->tx_errors++;
1110         }
1111         u64_stats_update_end(&tstats->syncp);
1112         u64_stats_update_end(&sstats->syncp);
1113
1114         return 0;
1115 }
1116
1117 /* Automatically called when the skb is freed.
1118  */
1119 static void l2tp_sock_wfree(struct sk_buff *skb)
1120 {
1121         sock_put(skb->sk);
1122 }
1123
1124 /* For data skbs that we transmit, we associate with the tunnel socket
1125  * but don't do accounting.
1126  */
1127 static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
1128 {
1129         sock_hold(sk);
1130         skb->sk = sk;
1131         skb->destructor = l2tp_sock_wfree;
1132 }
1133
1134 #if IS_ENABLED(CONFIG_IPV6)
1135 static void l2tp_xmit_ipv6_csum(struct sock *sk, struct sk_buff *skb,
1136                                 int udp_len)
1137 {
1138         struct ipv6_pinfo *np = inet6_sk(sk);
1139         struct udphdr *uh = udp_hdr(skb);
1140
1141         if (!skb_dst(skb) || !skb_dst(skb)->dev ||
1142             !(skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
1143                 __wsum csum = skb_checksum(skb, 0, udp_len, 0);
1144                 skb->ip_summed = CHECKSUM_UNNECESSARY;
1145                 uh->check = csum_ipv6_magic(&np->saddr, &np->daddr, udp_len,
1146                                             IPPROTO_UDP, csum);
1147                 if (uh->check == 0)
1148                         uh->check = CSUM_MANGLED_0;
1149         } else {
1150                 skb->ip_summed = CHECKSUM_PARTIAL;
1151                 skb->csum_start = skb_transport_header(skb) - skb->head;
1152                 skb->csum_offset = offsetof(struct udphdr, check);
1153                 uh->check = ~csum_ipv6_magic(&np->saddr, &np->daddr,
1154                                              udp_len, IPPROTO_UDP, 0);
1155         }
1156 }
1157 #endif
1158
1159 /* If caller requires the skb to have a ppp header, the header must be
1160  * inserted in the skb data before calling this function.
1161  */
1162 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1163 {
1164         int data_len = skb->len;
1165         struct l2tp_tunnel *tunnel = session->tunnel;
1166         struct sock *sk = tunnel->sock;
1167         struct flowi *fl;
1168         struct udphdr *uh;
1169         struct inet_sock *inet;
1170         __wsum csum;
1171         int headroom;
1172         int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1173         int udp_len;
1174         int ret = NET_XMIT_SUCCESS;
1175
1176         /* Check that there's enough headroom in the skb to insert IP,
1177          * UDP and L2TP headers. If not enough, expand it to
1178          * make room. Adjust truesize.
1179          */
1180         headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1181                 uhlen + hdr_len;
1182         if (skb_cow_head(skb, headroom)) {
1183                 kfree_skb(skb);
1184                 return NET_XMIT_DROP;
1185         }
1186
1187         skb_orphan(skb);
1188         /* Setup L2TP header */
1189         session->build_header(session, __skb_push(skb, hdr_len));
1190
1191         /* Reset skb netfilter state */
1192         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1193         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1194                               IPSKB_REROUTED);
1195         nf_reset(skb);
1196
1197         bh_lock_sock(sk);
1198         if (sock_owned_by_user(sk)) {
1199                 kfree_skb(skb);
1200                 ret = NET_XMIT_DROP;
1201                 goto out_unlock;
1202         }
1203
1204         /* Get routing info from the tunnel socket */
1205         skb_dst_drop(skb);
1206         skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
1207
1208         inet = inet_sk(sk);
1209         fl = &inet->cork.fl;
1210         switch (tunnel->encap) {
1211         case L2TP_ENCAPTYPE_UDP:
1212                 /* Setup UDP header */
1213                 __skb_push(skb, sizeof(*uh));
1214                 skb_reset_transport_header(skb);
1215                 uh = udp_hdr(skb);
1216                 uh->source = inet->inet_sport;
1217                 uh->dest = inet->inet_dport;
1218                 udp_len = uhlen + hdr_len + data_len;
1219                 uh->len = htons(udp_len);
1220                 uh->check = 0;
1221
1222                 /* Calculate UDP checksum if configured to do so */
1223 #if IS_ENABLED(CONFIG_IPV6)
1224                 if (sk->sk_family == PF_INET6)
1225                         l2tp_xmit_ipv6_csum(sk, skb, udp_len);
1226                 else
1227 #endif
1228                 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1229                         skb->ip_summed = CHECKSUM_NONE;
1230                 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1231                          (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1232                         skb->ip_summed = CHECKSUM_COMPLETE;
1233                         csum = skb_checksum(skb, 0, udp_len, 0);
1234                         uh->check = csum_tcpudp_magic(inet->inet_saddr,
1235                                                       inet->inet_daddr,
1236                                                       udp_len, IPPROTO_UDP, csum);
1237                         if (uh->check == 0)
1238                                 uh->check = CSUM_MANGLED_0;
1239                 } else {
1240                         skb->ip_summed = CHECKSUM_PARTIAL;
1241                         skb->csum_start = skb_transport_header(skb) - skb->head;
1242                         skb->csum_offset = offsetof(struct udphdr, check);
1243                         uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1244                                                        inet->inet_daddr,
1245                                                        udp_len, IPPROTO_UDP, 0);
1246                 }
1247                 break;
1248
1249         case L2TP_ENCAPTYPE_IP:
1250                 break;
1251         }
1252
1253         l2tp_skb_set_owner_w(skb, sk);
1254
1255         l2tp_xmit_core(session, skb, fl, data_len);
1256 out_unlock:
1257         bh_unlock_sock(sk);
1258
1259         return ret;
1260 }
1261 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1262
1263 /*****************************************************************************
1264  * Tinnel and session create/destroy.
1265  *****************************************************************************/
1266
1267 /* Tunnel socket destruct hook.
1268  * The tunnel context is deleted only when all session sockets have been
1269  * closed.
1270  */
1271 static void l2tp_tunnel_destruct(struct sock *sk)
1272 {
1273         struct l2tp_tunnel *tunnel;
1274
1275         tunnel = sk->sk_user_data;
1276         if (tunnel == NULL)
1277                 goto end;
1278
1279         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1280
1281         /* Close all sessions */
1282         l2tp_tunnel_closeall(tunnel);
1283
1284         switch (tunnel->encap) {
1285         case L2TP_ENCAPTYPE_UDP:
1286                 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1287                 (udp_sk(sk))->encap_type = 0;
1288                 (udp_sk(sk))->encap_rcv = NULL;
1289                 break;
1290         case L2TP_ENCAPTYPE_IP:
1291                 break;
1292         }
1293
1294         /* Remove hooks into tunnel socket */
1295         tunnel->sock = NULL;
1296         sk->sk_destruct = tunnel->old_sk_destruct;
1297         sk->sk_user_data = NULL;
1298
1299         /* Call the original destructor */
1300         if (sk->sk_destruct)
1301                 (*sk->sk_destruct)(sk);
1302
1303         /* We're finished with the socket */
1304         l2tp_tunnel_dec_refcount(tunnel);
1305
1306 end:
1307         return;
1308 }
1309
1310 /* When the tunnel is closed, all the attached sessions need to go too.
1311  */
1312 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1313 {
1314         int hash;
1315         struct hlist_node *walk;
1316         struct hlist_node *tmp;
1317         struct l2tp_session *session;
1318
1319         BUG_ON(tunnel == NULL);
1320
1321         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1322                   tunnel->name);
1323
1324         write_lock_bh(&tunnel->hlist_lock);
1325         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1326 again:
1327                 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1328                         session = hlist_entry(walk, struct l2tp_session, hlist);
1329
1330                         l2tp_info(session, L2TP_MSG_CONTROL,
1331                                   "%s: closing session\n", session->name);
1332
1333                         hlist_del_init(&session->hlist);
1334
1335                         /* Since we should hold the sock lock while
1336                          * doing any unbinding, we need to release the
1337                          * lock we're holding before taking that lock.
1338                          * Hold a reference to the sock so it doesn't
1339                          * disappear as we're jumping between locks.
1340                          */
1341                         if (session->ref != NULL)
1342                                 (*session->ref)(session);
1343
1344                         write_unlock_bh(&tunnel->hlist_lock);
1345
1346                         if (tunnel->version != L2TP_HDR_VER_2) {
1347                                 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1348
1349                                 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1350                                 hlist_del_init_rcu(&session->global_hlist);
1351                                 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1352                                 synchronize_rcu();
1353                         }
1354
1355                         if (session->session_close != NULL)
1356                                 (*session->session_close)(session);
1357
1358                         if (session->deref != NULL)
1359                                 (*session->deref)(session);
1360
1361                         write_lock_bh(&tunnel->hlist_lock);
1362
1363                         /* Now restart from the beginning of this hash
1364                          * chain.  We always remove a session from the
1365                          * list so we are guaranteed to make forward
1366                          * progress.
1367                          */
1368                         goto again;
1369                 }
1370         }
1371         write_unlock_bh(&tunnel->hlist_lock);
1372 }
1373
1374 /* Really kill the tunnel.
1375  * Come here only when all sessions have been cleared from the tunnel.
1376  */
1377 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1378 {
1379         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1380
1381         BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1382         BUG_ON(tunnel->sock != NULL);
1383
1384         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name);
1385
1386         /* Remove from tunnel list */
1387         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1388         list_del_rcu(&tunnel->list);
1389         kfree_rcu(tunnel, rcu);
1390         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1391
1392         atomic_dec(&l2tp_tunnel_count);
1393 }
1394
1395 /* Create a socket for the tunnel, if one isn't set up by
1396  * userspace. This is used for static tunnels where there is no
1397  * managing L2TP daemon.
1398  */
1399 static int l2tp_tunnel_sock_create(u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct socket **sockp)
1400 {
1401         int err = -EINVAL;
1402         struct sockaddr_in udp_addr;
1403 #if IS_ENABLED(CONFIG_IPV6)
1404         struct sockaddr_in6 udp6_addr;
1405         struct sockaddr_l2tpip6 ip6_addr;
1406 #endif
1407         struct sockaddr_l2tpip ip_addr;
1408         struct socket *sock = NULL;
1409
1410         switch (cfg->encap) {
1411         case L2TP_ENCAPTYPE_UDP:
1412 #if IS_ENABLED(CONFIG_IPV6)
1413                 if (cfg->local_ip6 && cfg->peer_ip6) {
1414                         err = sock_create(AF_INET6, SOCK_DGRAM, 0, sockp);
1415                         if (err < 0)
1416                                 goto out;
1417
1418                         sock = *sockp;
1419
1420                         memset(&udp6_addr, 0, sizeof(udp6_addr));
1421                         udp6_addr.sin6_family = AF_INET6;
1422                         memcpy(&udp6_addr.sin6_addr, cfg->local_ip6,
1423                                sizeof(udp6_addr.sin6_addr));
1424                         udp6_addr.sin6_port = htons(cfg->local_udp_port);
1425                         err = kernel_bind(sock, (struct sockaddr *) &udp6_addr,
1426                                           sizeof(udp6_addr));
1427                         if (err < 0)
1428                                 goto out;
1429
1430                         udp6_addr.sin6_family = AF_INET6;
1431                         memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6,
1432                                sizeof(udp6_addr.sin6_addr));
1433                         udp6_addr.sin6_port = htons(cfg->peer_udp_port);
1434                         err = kernel_connect(sock,
1435                                              (struct sockaddr *) &udp6_addr,
1436                                              sizeof(udp6_addr), 0);
1437                         if (err < 0)
1438                                 goto out;
1439                 } else
1440 #endif
1441                 {
1442                         err = sock_create(AF_INET, SOCK_DGRAM, 0, sockp);
1443                         if (err < 0)
1444                                 goto out;
1445
1446                         sock = *sockp;
1447
1448                         memset(&udp_addr, 0, sizeof(udp_addr));
1449                         udp_addr.sin_family = AF_INET;
1450                         udp_addr.sin_addr = cfg->local_ip;
1451                         udp_addr.sin_port = htons(cfg->local_udp_port);
1452                         err = kernel_bind(sock, (struct sockaddr *) &udp_addr,
1453                                           sizeof(udp_addr));
1454                         if (err < 0)
1455                                 goto out;
1456
1457                         udp_addr.sin_family = AF_INET;
1458                         udp_addr.sin_addr = cfg->peer_ip;
1459                         udp_addr.sin_port = htons(cfg->peer_udp_port);
1460                         err = kernel_connect(sock,
1461                                              (struct sockaddr *) &udp_addr,
1462                                              sizeof(udp_addr), 0);
1463                         if (err < 0)
1464                                 goto out;
1465                 }
1466
1467                 if (!cfg->use_udp_checksums)
1468                         sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1469
1470                 break;
1471
1472         case L2TP_ENCAPTYPE_IP:
1473 #if IS_ENABLED(CONFIG_IPV6)
1474                 if (cfg->local_ip6 && cfg->peer_ip6) {
1475                         err = sock_create(AF_INET6, SOCK_DGRAM, IPPROTO_L2TP,
1476                                           sockp);
1477                         if (err < 0)
1478                                 goto out;
1479
1480                         sock = *sockp;
1481
1482                         memset(&ip6_addr, 0, sizeof(ip6_addr));
1483                         ip6_addr.l2tp_family = AF_INET6;
1484                         memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1485                                sizeof(ip6_addr.l2tp_addr));
1486                         ip6_addr.l2tp_conn_id = tunnel_id;
1487                         err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1488                                           sizeof(ip6_addr));
1489                         if (err < 0)
1490                                 goto out;
1491
1492                         ip6_addr.l2tp_family = AF_INET6;
1493                         memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1494                                sizeof(ip6_addr.l2tp_addr));
1495                         ip6_addr.l2tp_conn_id = peer_tunnel_id;
1496                         err = kernel_connect(sock,
1497                                              (struct sockaddr *) &ip6_addr,
1498                                              sizeof(ip6_addr), 0);
1499                         if (err < 0)
1500                                 goto out;
1501                 } else
1502 #endif
1503                 {
1504                         err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_L2TP,
1505                                           sockp);
1506                         if (err < 0)
1507                                 goto out;
1508
1509                         sock = *sockp;
1510
1511                         memset(&ip_addr, 0, sizeof(ip_addr));
1512                         ip_addr.l2tp_family = AF_INET;
1513                         ip_addr.l2tp_addr = cfg->local_ip;
1514                         ip_addr.l2tp_conn_id = tunnel_id;
1515                         err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1516                                           sizeof(ip_addr));
1517                         if (err < 0)
1518                                 goto out;
1519
1520                         ip_addr.l2tp_family = AF_INET;
1521                         ip_addr.l2tp_addr = cfg->peer_ip;
1522                         ip_addr.l2tp_conn_id = peer_tunnel_id;
1523                         err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1524                                              sizeof(ip_addr), 0);
1525                         if (err < 0)
1526                                 goto out;
1527                 }
1528                 break;
1529
1530         default:
1531                 goto out;
1532         }
1533
1534 out:
1535         if ((err < 0) && sock) {
1536                 sock_release(sock);
1537                 *sockp = NULL;
1538         }
1539
1540         return err;
1541 }
1542
1543 static struct lock_class_key l2tp_socket_class;
1544
1545 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)
1546 {
1547         struct l2tp_tunnel *tunnel = NULL;
1548         int err;
1549         struct socket *sock = NULL;
1550         struct sock *sk = NULL;
1551         struct l2tp_net *pn;
1552         enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1553
1554         /* Get the tunnel socket from the fd, which was opened by
1555          * the userspace L2TP daemon. If not specified, create a
1556          * kernel socket.
1557          */
1558         if (fd < 0) {
1559                 err = l2tp_tunnel_sock_create(tunnel_id, peer_tunnel_id, cfg, &sock);
1560                 if (err < 0)
1561                         goto err;
1562         } else {
1563                 err = -EBADF;
1564                 sock = sockfd_lookup(fd, &err);
1565                 if (!sock) {
1566                         pr_err("tunl %hu: sockfd_lookup(fd=%d) returned %d\n",
1567                                tunnel_id, fd, err);
1568                         goto err;
1569                 }
1570         }
1571
1572         sk = sock->sk;
1573
1574         if (cfg != NULL)
1575                 encap = cfg->encap;
1576
1577         /* Quick sanity checks */
1578         switch (encap) {
1579         case L2TP_ENCAPTYPE_UDP:
1580                 err = -EPROTONOSUPPORT;
1581                 if (sk->sk_protocol != IPPROTO_UDP) {
1582                         pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1583                                tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1584                         goto err;
1585                 }
1586                 break;
1587         case L2TP_ENCAPTYPE_IP:
1588                 err = -EPROTONOSUPPORT;
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 = (struct l2tp_tunnel *)sk->sk_user_data;
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
1620         /* The net we belong to */
1621         tunnel->l2tp_net = net;
1622         pn = l2tp_pernet(net);
1623
1624         if (cfg != NULL)
1625                 tunnel->debug = cfg->debug;
1626
1627         /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1628         tunnel->encap = encap;
1629         if (encap == L2TP_ENCAPTYPE_UDP) {
1630                 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1631                 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1632                 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1633 #if IS_ENABLED(CONFIG_IPV6)
1634                 if (sk->sk_family == PF_INET6)
1635                         udpv6_encap_enable();
1636                 else
1637 #endif
1638                 udp_encap_enable();
1639         }
1640
1641         sk->sk_user_data = tunnel;
1642
1643         /* Hook on the tunnel socket destructor so that we can cleanup
1644          * if the tunnel socket goes away.
1645          */
1646         tunnel->old_sk_destruct = sk->sk_destruct;
1647         sk->sk_destruct = &l2tp_tunnel_destruct;
1648         tunnel->sock = sk;
1649         tunnel->fd = fd;
1650         lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
1651
1652         sk->sk_allocation = GFP_ATOMIC;
1653
1654         /* Add tunnel to our list */
1655         INIT_LIST_HEAD(&tunnel->list);
1656         atomic_inc(&l2tp_tunnel_count);
1657
1658         /* Bump the reference count. The tunnel context is deleted
1659          * only when this drops to zero. Must be done before list insertion
1660          */
1661         l2tp_tunnel_inc_refcount(tunnel);
1662         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1663         list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1664         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1665
1666         err = 0;
1667 err:
1668         if (tunnelp)
1669                 *tunnelp = tunnel;
1670
1671         /* If tunnel's socket was created by the kernel, it doesn't
1672          *  have a file.
1673          */
1674         if (sock && sock->file)
1675                 sockfd_put(sock);
1676
1677         return err;
1678 }
1679 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1680
1681 /* This function is used by the netlink TUNNEL_DELETE command.
1682  */
1683 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1684 {
1685         int err = -EBADF;
1686         struct socket *sock = NULL;
1687         struct sock *sk = NULL;
1688
1689         sk = l2tp_tunnel_sock_lookup(tunnel);
1690         if (!sk)
1691                 goto out;
1692
1693         sock = sk->sk_socket;
1694         BUG_ON(!sock);
1695
1696         /* Force the tunnel socket to close. This will eventually
1697          * cause the tunnel to be deleted via the normal socket close
1698          * mechanisms when userspace closes the tunnel socket.
1699          */
1700         err = inet_shutdown(sock, 2);
1701
1702         /* If the tunnel's socket was created by the kernel,
1703          * close the socket here since the socket was not
1704          * created by userspace.
1705          */
1706         if (sock->file == NULL)
1707                 err = inet_release(sock);
1708
1709         l2tp_tunnel_sock_put(sk);
1710 out:
1711         return err;
1712 }
1713 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1714
1715 /* Really kill the session.
1716  */
1717 void l2tp_session_free(struct l2tp_session *session)
1718 {
1719         struct l2tp_tunnel *tunnel;
1720
1721         BUG_ON(atomic_read(&session->ref_count) != 0);
1722
1723         tunnel = session->tunnel;
1724         if (tunnel != NULL) {
1725                 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1726
1727                 /* Delete the session from the hash */
1728                 write_lock_bh(&tunnel->hlist_lock);
1729                 hlist_del_init(&session->hlist);
1730                 write_unlock_bh(&tunnel->hlist_lock);
1731
1732                 /* Unlink from the global hash if not L2TPv2 */
1733                 if (tunnel->version != L2TP_HDR_VER_2) {
1734                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1735
1736                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1737                         hlist_del_init_rcu(&session->global_hlist);
1738                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1739                         synchronize_rcu();
1740                 }
1741
1742                 if (session->session_id != 0)
1743                         atomic_dec(&l2tp_session_count);
1744
1745                 sock_put(tunnel->sock);
1746
1747                 /* This will delete the tunnel context if this
1748                  * is the last session on the tunnel.
1749                  */
1750                 session->tunnel = NULL;
1751                 l2tp_tunnel_dec_refcount(tunnel);
1752         }
1753
1754         kfree(session);
1755
1756         return;
1757 }
1758 EXPORT_SYMBOL_GPL(l2tp_session_free);
1759
1760 /* This function is used by the netlink SESSION_DELETE command and by
1761    pseudowire modules.
1762  */
1763 int l2tp_session_delete(struct l2tp_session *session)
1764 {
1765         if (session->session_close != NULL)
1766                 (*session->session_close)(session);
1767
1768         l2tp_session_dec_refcount(session);
1769
1770         return 0;
1771 }
1772 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1773
1774
1775 /* We come here whenever a session's send_seq, cookie_len or
1776  * l2specific_len parameters are set.
1777  */
1778 static void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1779 {
1780         if (version == L2TP_HDR_VER_2) {
1781                 session->hdr_len = 6;
1782                 if (session->send_seq)
1783                         session->hdr_len += 4;
1784         } else {
1785                 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1786                 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1787                         session->hdr_len += 4;
1788         }
1789
1790 }
1791
1792 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)
1793 {
1794         struct l2tp_session *session;
1795
1796         session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1797         if (session != NULL) {
1798                 session->magic = L2TP_SESSION_MAGIC;
1799                 session->tunnel = tunnel;
1800
1801                 session->session_id = session_id;
1802                 session->peer_session_id = peer_session_id;
1803                 session->nr = 0;
1804
1805                 sprintf(&session->name[0], "sess %u/%u",
1806                         tunnel->tunnel_id, session->session_id);
1807
1808                 skb_queue_head_init(&session->reorder_q);
1809
1810                 INIT_HLIST_NODE(&session->hlist);
1811                 INIT_HLIST_NODE(&session->global_hlist);
1812
1813                 /* Inherit debug options from tunnel */
1814                 session->debug = tunnel->debug;
1815
1816                 if (cfg) {
1817                         session->pwtype = cfg->pw_type;
1818                         session->debug = cfg->debug;
1819                         session->mtu = cfg->mtu;
1820                         session->mru = cfg->mru;
1821                         session->send_seq = cfg->send_seq;
1822                         session->recv_seq = cfg->recv_seq;
1823                         session->lns_mode = cfg->lns_mode;
1824                         session->reorder_timeout = cfg->reorder_timeout;
1825                         session->offset = cfg->offset;
1826                         session->l2specific_type = cfg->l2specific_type;
1827                         session->l2specific_len = cfg->l2specific_len;
1828                         session->cookie_len = cfg->cookie_len;
1829                         memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1830                         session->peer_cookie_len = cfg->peer_cookie_len;
1831                         memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1832                 }
1833
1834                 if (tunnel->version == L2TP_HDR_VER_2)
1835                         session->build_header = l2tp_build_l2tpv2_header;
1836                 else
1837                         session->build_header = l2tp_build_l2tpv3_header;
1838
1839                 l2tp_session_set_header_len(session, tunnel->version);
1840
1841                 /* Bump the reference count. The session context is deleted
1842                  * only when this drops to zero.
1843                  */
1844                 l2tp_session_inc_refcount(session);
1845                 l2tp_tunnel_inc_refcount(tunnel);
1846
1847                 /* Ensure tunnel socket isn't deleted */
1848                 sock_hold(tunnel->sock);
1849
1850                 /* Add session to the tunnel's hash list */
1851                 write_lock_bh(&tunnel->hlist_lock);
1852                 hlist_add_head(&session->hlist,
1853                                l2tp_session_id_hash(tunnel, session_id));
1854                 write_unlock_bh(&tunnel->hlist_lock);
1855
1856                 /* And to the global session list if L2TPv3 */
1857                 if (tunnel->version != L2TP_HDR_VER_2) {
1858                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1859
1860                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1861                         hlist_add_head_rcu(&session->global_hlist,
1862                                            l2tp_session_id_hash_2(pn, session_id));
1863                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1864                 }
1865
1866                 /* Ignore management session in session count value */
1867                 if (session->session_id != 0)
1868                         atomic_inc(&l2tp_session_count);
1869         }
1870
1871         return session;
1872 }
1873 EXPORT_SYMBOL_GPL(l2tp_session_create);
1874
1875 /*****************************************************************************
1876  * Init and cleanup
1877  *****************************************************************************/
1878
1879 static __net_init int l2tp_init_net(struct net *net)
1880 {
1881         struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1882         int hash;
1883
1884         INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1885         spin_lock_init(&pn->l2tp_tunnel_list_lock);
1886
1887         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1888                 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1889
1890         spin_lock_init(&pn->l2tp_session_hlist_lock);
1891
1892         return 0;
1893 }
1894
1895 static struct pernet_operations l2tp_net_ops = {
1896         .init = l2tp_init_net,
1897         .id   = &l2tp_net_id,
1898         .size = sizeof(struct l2tp_net),
1899 };
1900
1901 static int __init l2tp_init(void)
1902 {
1903         int rc = 0;
1904
1905         rc = register_pernet_device(&l2tp_net_ops);
1906         if (rc)
1907                 goto out;
1908
1909         pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
1910
1911 out:
1912         return rc;
1913 }
1914
1915 static void __exit l2tp_exit(void)
1916 {
1917         unregister_pernet_device(&l2tp_net_ops);
1918 }
1919
1920 module_init(l2tp_init);
1921 module_exit(l2tp_exit);
1922
1923 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1924 MODULE_DESCRIPTION("L2TP core");
1925 MODULE_LICENSE("GPL");
1926 MODULE_VERSION(L2TP_DRV_VERSION);
1927