Pileus Git - ~andy/linux/blob - 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 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 static void l2tp_session_set_header_len(struct l2tp_session *session, int version);
 116 static void l2tp_tunnel_free(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 /* Tunnel reference counts. Incremented per session that is added to
 126  * the tunnel.
 127  */
 128 static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
 129 {
 130         atomic_inc(&tunnel->ref_count);
 131 }
 132
 133 static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
 134 {
 135         if (atomic_dec_and_test(&tunnel->ref_count))
 136                 l2tp_tunnel_free(tunnel);
 137 }
 138 #ifdef L2TP_REFCNT_DEBUG
 139 #define l2tp_tunnel_inc_refcount(_t)                                    \
 140 do {                                                                    \
 141         pr_debug("l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n",        \
 142                  __func__, __LINE__, (_t)->name,                        \
 143                  atomic_read(&_t->ref_count));                          \
 144         l2tp_tunnel_inc_refcount_1(_t);                                 \
 145 } while (0)
 146 #define l2tp_tunnel_dec_refcount(_t)
 147 do {                                                                    \
 148         pr_debug("l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n",        \
 149                  __func__, __LINE__, (_t)->name,                        \
 150                  atomic_read(&_t->ref_count));                          \
 151         l2tp_tunnel_dec_refcount_1(_t);                                 \
 152 } while (0)
 153 #else
 154 #define l2tp_tunnel_inc_refcount(t) l2tp_tunnel_inc_refcount_1(t)
 155 #define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t)
 156 #endif
 157
 158 /* Session hash global list for L2TPv3.
 159  * The session_id SHOULD be random according to RFC3931, but several
 160  * L2TP implementations use incrementing session_ids.  So we do a real
 161  * hash on the session_id, rather than a simple bitmask.
 162  */
 163 static inline struct hlist_head *
 164 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
 165 {
 166         return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
 167
 168 }
 169
 170 /* Lookup the tunnel socket, possibly involving the fs code if the socket is
 171  * owned by userspace.  A struct sock returned from this function must be
 172  * released using l2tp_tunnel_sock_put once you're done with it.
 173  */
 174 struct sock *l2tp_tunnel_sock_lookup(struct l2tp_tunnel *tunnel)
 175 {
 176         int err = 0;
 177         struct socket *sock = NULL;
 178         struct sock *sk = NULL;
 179
 180         if (!tunnel)
 181                 goto out;
 182
 183         if (tunnel->fd >= 0) {
 184                 /* Socket is owned by userspace, who might be in the process
 185                  * of closing it.  Look the socket up using the fd to ensure
 186                  * consistency.
 187                  */
 188                 sock = sockfd_lookup(tunnel->fd, &err);
 189                 if (sock)
 190                         sk = sock->sk;
 191         } else {
 192                 /* Socket is owned by kernelspace */
 193                 sk = tunnel->sock;
 194                 sock_hold(sk);
 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         sock_put(sk);
 214 }
 215 EXPORT_SYMBOL_GPL(l2tp_tunnel_sock_put);
 216
 217 /* Lookup a session by id in the global session list
 218  */
 219 static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
 220 {
 221         struct l2tp_net *pn = l2tp_pernet(net);
 222         struct hlist_head *session_list =
 223                 l2tp_session_id_hash_2(pn, session_id);
 224         struct l2tp_session *session;
 225
 226         rcu_read_lock_bh();
 227         hlist_for_each_entry_rcu(session, 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
 257         /* In L2TPv3, session_ids are unique over all tunnels and we
 258          * sometimes need to look them up before we know the
 259          * tunnel.
 260          */
 261         if (tunnel == NULL)
 262                 return l2tp_session_find_2(net, session_id);
 263
 264         session_list = l2tp_session_id_hash(tunnel, session_id);
 265         read_lock_bh(&tunnel->hlist_lock);
 266         hlist_for_each_entry(session, session_list, hlist) {
 267                 if (session->session_id == session_id) {
 268                         read_unlock_bh(&tunnel->hlist_lock);
 269                         return session;
 270                 }
 271         }
 272         read_unlock_bh(&tunnel->hlist_lock);
 273
 274         return NULL;
 275 }
 276 EXPORT_SYMBOL_GPL(l2tp_session_find);
 277
 278 struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
 279 {
 280         int hash;
 281         struct l2tp_session *session;
 282         int count = 0;
 283
 284         read_lock_bh(&tunnel->hlist_lock);
 285         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
 286                 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) {
 287                         if (++count > nth) {
 288                                 read_unlock_bh(&tunnel->hlist_lock);
 289                                 return session;
 290                         }
 291                 }
 292         }
 293
 294         read_unlock_bh(&tunnel->hlist_lock);
 295
 296         return NULL;
 297 }
 298 EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
 299
 300 /* Lookup a session by interface name.
 301  * This is very inefficient but is only used by management interfaces.
 302  */
 303 struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
 304 {
 305         struct l2tp_net *pn = l2tp_pernet(net);
 306         int hash;
 307         struct l2tp_session *session;
 308
 309         rcu_read_lock_bh();
 310         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
 311                 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) {
 312                         if (!strcmp(session->ifname, ifname)) {
 313                                 rcu_read_unlock_bh();
 314                                 return session;
 315                         }
 316                 }
 317         }
 318
 319         rcu_read_unlock_bh();
 320
 321         return NULL;
 322 }
 323 EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
 324
 325 /* Lookup a tunnel by id
 326  */
 327 struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
 328 {
 329         struct l2tp_tunnel *tunnel;
 330         struct l2tp_net *pn = l2tp_pernet(net);
 331
 332         rcu_read_lock_bh();
 333         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 334                 if (tunnel->tunnel_id == tunnel_id) {
 335                         rcu_read_unlock_bh();
 336                         return tunnel;
 337                 }
 338         }
 339         rcu_read_unlock_bh();
 340
 341         return NULL;
 342 }
 343 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
 344
 345 struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
 346 {
 347         struct l2tp_net *pn = l2tp_pernet(net);
 348         struct l2tp_tunnel *tunnel;
 349         int count = 0;
 350
 351         rcu_read_lock_bh();
 352         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 353                 if (++count > nth) {
 354                         rcu_read_unlock_bh();
 355                         return tunnel;
 356                 }
 357         }
 358
 359         rcu_read_unlock_bh();
 360
 361         return NULL;
 362 }
 363 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
 364
 365 /*****************************************************************************
 366  * Receive data handling
 367  *****************************************************************************/
 368
 369 /* Queue a skb in order. We come here only if the skb has an L2TP sequence
 370  * number.
 371  */
 372 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
 373 {
 374         struct sk_buff *skbp;
 375         struct sk_buff *tmp;
 376         u32 ns = L2TP_SKB_CB(skb)->ns;
 377
 378         spin_lock_bh(&session->reorder_q.lock);
 379         skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
 380                 if (L2TP_SKB_CB(skbp)->ns > ns) {
 381                         __skb_queue_before(&session->reorder_q, skbp, skb);
 382                         l2tp_dbg(session, L2TP_MSG_SEQ,
 383                                  "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
 384                                  session->name, ns, L2TP_SKB_CB(skbp)->ns,
 385                                  skb_queue_len(&session->reorder_q));
 386                         atomic_long_inc(&session->stats.rx_oos_packets);
 387                         goto out;
 388                 }
 389         }
 390
 391         __skb_queue_tail(&session->reorder_q, skb);
 392
 393 out:
 394         spin_unlock_bh(&session->reorder_q.lock);
 395 }
 396
 397 /* Dequeue a single skb.
 398  */
 399 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
 400 {
 401         struct l2tp_tunnel *tunnel = session->tunnel;
 402         int length = L2TP_SKB_CB(skb)->length;
 403
 404         /* We're about to requeue the skb, so return resources
 405          * to its current owner (a socket receive buffer).
 406          */
 407         skb_orphan(skb);
 408
 409         atomic_long_inc(&tunnel->stats.rx_packets);
 410         atomic_long_add(length, &tunnel->stats.rx_bytes);
 411         atomic_long_inc(&session->stats.rx_packets);
 412         atomic_long_add(length, &session->stats.rx_bytes);
 413
 414         if (L2TP_SKB_CB(skb)->has_seq) {
 415                 /* Bump our Nr */
 416                 session->nr++;
 417                 session->nr &= session->nr_max;
 418
 419                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
 420                          session->name, session->nr);
 421         }
 422
 423         /* call private receive handler */
 424         if (session->recv_skb != NULL)
 425                 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
 426         else
 427                 kfree_skb(skb);
 428
 429         if (session->deref)
 430                 (*session->deref)(session);
 431 }
 432
 433 /* Dequeue skbs from the session's reorder_q, subject to packet order.
 434  * Skbs that have been in the queue for too long are simply discarded.
 435  */
 436 static void l2tp_recv_dequeue(struct l2tp_session *session)
 437 {
 438         struct sk_buff *skb;
 439         struct sk_buff *tmp;
 440
 441         /* If the pkt at the head of the queue has the nr that we
 442          * expect to send up next, dequeue it and any other
 443          * in-sequence packets behind it.
 444          */
 445 start:
 446         spin_lock_bh(&session->reorder_q.lock);
 447         skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
 448                 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
 449                         atomic_long_inc(&session->stats.rx_seq_discards);
 450                         atomic_long_inc(&session->stats.rx_errors);
 451                         l2tp_dbg(session, L2TP_MSG_SEQ,
 452                                  "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
 453                                  session->name, L2TP_SKB_CB(skb)->ns,
 454                                  L2TP_SKB_CB(skb)->length, session->nr,
 455                                  skb_queue_len(&session->reorder_q));
 456                         session->reorder_skip = 1;
 457                         __skb_unlink(skb, &session->reorder_q);
 458                         kfree_skb(skb);
 459                         if (session->deref)
 460                                 (*session->deref)(session);
 461                         continue;
 462                 }
 463
 464                 if (L2TP_SKB_CB(skb)->has_seq) {
 465                         if (session->reorder_skip) {
 466                                 l2tp_dbg(session, L2TP_MSG_SEQ,
 467                                          "%s: advancing nr to next pkt: %u -> %u",
 468                                          session->name, session->nr,
 469                                          L2TP_SKB_CB(skb)->ns);
 470                                 session->reorder_skip = 0;
 471                                 session->nr = L2TP_SKB_CB(skb)->ns;
 472                         }
 473                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
 474                                 l2tp_dbg(session, L2TP_MSG_SEQ,
 475                                          "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
 476                                          session->name, L2TP_SKB_CB(skb)->ns,
 477                                          L2TP_SKB_CB(skb)->length, session->nr,
 478                                          skb_queue_len(&session->reorder_q));
 479                                 goto out;
 480                         }
 481                 }
 482                 __skb_unlink(skb, &session->reorder_q);
 483
 484                 /* Process the skb. We release the queue lock while we
 485                  * do so to let other contexts process the queue.
 486                  */
 487                 spin_unlock_bh(&session->reorder_q.lock);
 488                 l2tp_recv_dequeue_skb(session, skb);
 489                 goto start;
 490         }
 491
 492 out:
 493         spin_unlock_bh(&session->reorder_q.lock);
 494 }
 495
 496 static inline int l2tp_verify_udp_checksum(struct sock *sk,
 497                                            struct sk_buff *skb)
 498 {
 499         struct udphdr *uh = udp_hdr(skb);
 500         u16 ulen = ntohs(uh->len);
 501         __wsum psum;
 502
 503         if (sk->sk_no_check || skb_csum_unnecessary(skb))
 504                 return 0;
 505
 506 #if IS_ENABLED(CONFIG_IPV6)
 507         if (sk->sk_family == PF_INET6) {
 508                 if (!uh->check) {
 509                         LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n");
 510                         return 1;
 511                 }
 512                 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
 513                     !csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
 514                                      &ipv6_hdr(skb)->daddr, ulen,
 515                                      IPPROTO_UDP, skb->csum)) {
 516                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 517                         return 0;
 518                 }
 519                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
 520                                                          &ipv6_hdr(skb)->daddr,
 521                                                          skb->len, IPPROTO_UDP,
 522                                                          0));
 523         } else
 524 #endif
 525         {
 526                 struct inet_sock *inet;
 527                 if (!uh->check)
 528                         return 0;
 529                 inet = inet_sk(sk);
 530                 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr,
 531                                           ulen, IPPROTO_UDP, 0);
 532
 533                 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
 534                     !csum_fold(csum_add(psum, skb->csum)))
 535                         return 0;
 536                 skb->csum = psum;
 537         }
 538
 539         return __skb_checksum_complete(skb);
 540 }
 541
 542 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr)
 543 {
 544         u32 nws;
 545
 546         if (nr >= session->nr)
 547                 nws = nr - session->nr;
 548         else
 549                 nws = (session->nr_max + 1) - (session->nr - nr);
 550
 551         return nws < session->nr_window_size;
 552 }
 553
 554 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if
 555  * acceptable, else non-zero.
 556  */
 557 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
 558 {
 559         if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) {
 560                 /* Packet sequence number is outside allowed window.
 561                  * Discard it.
 562                  */
 563                 l2tp_dbg(session, L2TP_MSG_SEQ,
 564                          "%s: pkt %u len %d discarded, outside window, nr=%u\n",
 565                          session->name, L2TP_SKB_CB(skb)->ns,
 566                          L2TP_SKB_CB(skb)->length, session->nr);
 567                 goto discard;
 568         }
 569
 570         if (session->reorder_timeout != 0) {
 571                 /* Packet reordering enabled. Add skb to session's
 572                  * reorder queue, in order of ns.
 573                  */
 574                 l2tp_recv_queue_skb(session, skb);
 575                 goto out;
 576         }
 577
 578         /* Packet reordering disabled. Discard out-of-sequence packets, while
 579          * tracking the number if in-sequence packets after the first OOS packet
 580          * is seen. After nr_oos_count_max in-sequence packets, reset the
 581          * sequence number to re-enable packet reception.
 582          */
 583         if (L2TP_SKB_CB(skb)->ns == session->nr) {
 584                 skb_queue_tail(&session->reorder_q, skb);
 585         } else {
 586                 u32 nr_oos = L2TP_SKB_CB(skb)->ns;
 587                 u32 nr_next = (session->nr_oos + 1) & session->nr_max;
 588
 589                 if (nr_oos == nr_next)
 590                         session->nr_oos_count++;
 591                 else
 592                         session->nr_oos_count = 0;
 593
 594                 session->nr_oos = nr_oos;
 595                 if (session->nr_oos_count > session->nr_oos_count_max) {
 596                         session->reorder_skip = 1;
 597                         l2tp_dbg(session, L2TP_MSG_SEQ,
 598                                  "%s: %d oos packets received. Resetting sequence numbers\n",
 599                                  session->name, session->nr_oos_count);
 600                 }
 601                 if (!session->reorder_skip) {
 602                         atomic_long_inc(&session->stats.rx_seq_discards);
 603                         l2tp_dbg(session, L2TP_MSG_SEQ,
 604                                  "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
 605                                  session->name, L2TP_SKB_CB(skb)->ns,
 606                                  L2TP_SKB_CB(skb)->length, session->nr,
 607                                  skb_queue_len(&session->reorder_q));
 608                         goto discard;
 609                 }
 610                 skb_queue_tail(&session->reorder_q, skb);
 611         }
 612
 613 out:
 614         return 0;
 615
 616 discard:
 617         return 1;
 618 }
 619
 620 /* Do receive processing of L2TP data frames. We handle both L2TPv2
 621  * and L2TPv3 data frames here.
 622  *
 623  * L2TPv2 Data Message Header
 624  *
 625  *  0                   1                   2                   3
 626  *  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
 627  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 628  * |T|L|x|x|S|x|O|P|x|x|x|x|  Ver  |          Length (opt)         |
 629  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 630  * |           Tunnel ID           |           Session ID          |
 631  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 632  * |             Ns (opt)          |             Nr (opt)          |
 633  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 634  * |      Offset Size (opt)        |    Offset pad... (opt)
 635  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 636  *
 637  * Data frames are marked by T=0. All other fields are the same as
 638  * those in L2TP control frames.
 639  *
 640  * L2TPv3 Data Message Header
 641  *
 642  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 643  * |                      L2TP Session Header                      |
 644  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 645  * |                      L2-Specific Sublayer                     |
 646  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 647  * |                        Tunnel Payload                      ...
 648  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 649  *
 650  * L2TPv3 Session Header Over IP
 651  *
 652  *  0                   1                   2                   3
 653  *  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
 654  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 655  * |                           Session ID                          |
 656  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 657  * |               Cookie (optional, maximum 64 bits)...
 658  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 659  *                                                                 |
 660  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 661  *
 662  * L2TPv3 L2-Specific Sublayer Format
 663  *
 664  *  0                   1                   2                   3
 665  *  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
 666  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 667  * |x|S|x|x|x|x|x|x|              Sequence Number                  |
 668  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 669  *
 670  * Cookie value, sublayer format and offset (pad) are negotiated with
 671  * the peer when the session is set up. Unlike L2TPv2, we do not need
 672  * to parse the packet header to determine if optional fields are
 673  * present.
 674  *
 675  * Caller must already have parsed the frame and determined that it is
 676  * a data (not control) frame before coming here. Fields up to the
 677  * session-id have already been parsed and ptr points to the data
 678  * after the session-id.
 679  */
 680 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 681                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 682                       int length, int (*payload_hook)(struct sk_buff *skb))
 683 {
 684         struct l2tp_tunnel *tunnel = session->tunnel;
 685         int offset;
 686         u32 ns, nr;
 687
 688         /* The ref count is increased since we now hold a pointer to
 689          * the session. Take care to decrement the refcnt when exiting
 690          * this function from now on...
 691          */
 692         l2tp_session_inc_refcount(session);
 693         if (session->ref)
 694                 (*session->ref)(session);
 695
 696         /* Parse and check optional cookie */
 697         if (session->peer_cookie_len > 0) {
 698                 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
 699                         l2tp_info(tunnel, L2TP_MSG_DATA,
 700                                   "%s: cookie mismatch (%u/%u). Discarding.\n",
 701                                   tunnel->name, tunnel->tunnel_id,
 702                                   session->session_id);
 703                         atomic_long_inc(&session->stats.rx_cookie_discards);
 704                         goto discard;
 705                 }
 706                 ptr += session->peer_cookie_len;
 707         }
 708
 709         /* Handle the optional sequence numbers. Sequence numbers are
 710          * in different places for L2TPv2 and L2TPv3.
 711          *
 712          * If we are the LAC, enable/disable sequence numbers under
 713          * the control of the LNS.  If no sequence numbers present but
 714          * we were expecting them, discard frame.
 715          */
 716         ns = nr = 0;
 717         L2TP_SKB_CB(skb)->has_seq = 0;
 718         if (tunnel->version == L2TP_HDR_VER_2) {
 719                 if (hdrflags & L2TP_HDRFLAG_S) {
 720                         ns = ntohs(*(__be16 *) ptr);
 721                         ptr += 2;
 722                         nr = ntohs(*(__be16 *) ptr);
 723                         ptr += 2;
 724
 725                         /* Store L2TP info in the skb */
 726                         L2TP_SKB_CB(skb)->ns = ns;
 727                         L2TP_SKB_CB(skb)->has_seq = 1;
 728
 729                         l2tp_dbg(session, L2TP_MSG_SEQ,
 730                                  "%s: recv data ns=%u, nr=%u, session nr=%u\n",
 731                                  session->name, ns, nr, session->nr);
 732                 }
 733         } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
 734                 u32 l2h = ntohl(*(__be32 *) ptr);
 735
 736                 if (l2h & 0x40000000) {
 737                         ns = l2h & 0x00ffffff;
 738
 739                         /* Store L2TP info in the skb */
 740                         L2TP_SKB_CB(skb)->ns = ns;
 741                         L2TP_SKB_CB(skb)->has_seq = 1;
 742
 743                         l2tp_dbg(session, L2TP_MSG_SEQ,
 744                                  "%s: recv data ns=%u, session nr=%u\n",
 745                                  session->name, ns, session->nr);
 746                 }
 747         }
 748
 749         /* Advance past L2-specific header, if present */
 750         ptr += session->l2specific_len;
 751
 752         if (L2TP_SKB_CB(skb)->has_seq) {
 753                 /* Received a packet with sequence numbers. If we're the LNS,
 754                  * check if we sre sending sequence numbers and if not,
 755                  * configure it so.
 756                  */
 757                 if ((!session->lns_mode) && (!session->send_seq)) {
 758                         l2tp_info(session, L2TP_MSG_SEQ,
 759                                   "%s: requested to enable seq numbers by LNS\n",
 760                                   session->name);
 761                         session->send_seq = -1;
 762                         l2tp_session_set_header_len(session, tunnel->version);
 763                 }
 764         } else {
 765                 /* No sequence numbers.
 766                  * If user has configured mandatory sequence numbers, discard.
 767                  */
 768                 if (session->recv_seq) {
 769                         l2tp_warn(session, L2TP_MSG_SEQ,
 770                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 771                                   session->name);
 772                         atomic_long_inc(&session->stats.rx_seq_discards);
 773                         goto discard;
 774                 }
 775
 776                 /* If we're the LAC and we're sending sequence numbers, the
 777                  * LNS has requested that we no longer send sequence numbers.
 778                  * If we're the LNS and we're sending sequence numbers, the
 779                  * LAC is broken. Discard the frame.
 780                  */
 781                 if ((!session->lns_mode) && (session->send_seq)) {
 782                         l2tp_info(session, L2TP_MSG_SEQ,
 783                                   "%s: requested to disable seq numbers by LNS\n",
 784                                   session->name);
 785                         session->send_seq = 0;
 786                         l2tp_session_set_header_len(session, tunnel->version);
 787                 } else if (session->send_seq) {
 788                         l2tp_warn(session, L2TP_MSG_SEQ,
 789                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 790                                   session->name);
 791                         atomic_long_inc(&session->stats.rx_seq_discards);
 792                         goto discard;
 793                 }
 794         }
 795
 796         /* Session data offset is handled differently for L2TPv2 and
 797          * L2TPv3. For L2TPv2, there is an optional 16-bit value in
 798          * the header. For L2TPv3, the offset is negotiated using AVPs
 799          * in the session setup control protocol.
 800          */
 801         if (tunnel->version == L2TP_HDR_VER_2) {
 802                 /* If offset bit set, skip it. */
 803                 if (hdrflags & L2TP_HDRFLAG_O) {
 804                         offset = ntohs(*(__be16 *)ptr);
 805                         ptr += 2 + offset;
 806                 }
 807         } else
 808                 ptr += session->offset;
 809
 810         offset = ptr - optr;
 811         if (!pskb_may_pull(skb, offset))
 812                 goto discard;
 813
 814         __skb_pull(skb, offset);
 815
 816         /* If caller wants to process the payload before we queue the
 817          * packet, do so now.
 818          */
 819         if (payload_hook)
 820                 if ((*payload_hook)(skb))
 821                         goto discard;
 822
 823         /* Prepare skb for adding to the session's reorder_q.  Hold
 824          * packets for max reorder_timeout or 1 second if not
 825          * reordering.
 826          */
 827         L2TP_SKB_CB(skb)->length = length;
 828         L2TP_SKB_CB(skb)->expires = jiffies +
 829                 (session->reorder_timeout ? session->reorder_timeout : HZ);
 830
 831         /* Add packet to the session's receive queue. Reordering is done here, if
 832          * enabled. Saved L2TP protocol info is stored in skb->sb[].
 833          */
 834         if (L2TP_SKB_CB(skb)->has_seq) {
 835                 if (l2tp_recv_data_seq(session, skb))
 836                         goto discard;
 837         } else {
 838                 /* No sequence numbers. Add the skb to the tail of the
 839                  * reorder queue. This ensures that it will be
 840                  * delivered after all previous sequenced skbs.
 841                  */
 842                 skb_queue_tail(&session->reorder_q, skb);
 843         }
 844
 845         /* Try to dequeue as many skbs from reorder_q as we can. */
 846         l2tp_recv_dequeue(session);
 847
 848         l2tp_session_dec_refcount(session);
 849
 850         return;
 851
 852 discard:
 853         atomic_long_inc(&session->stats.rx_errors);
 854         kfree_skb(skb);
 855
 856         if (session->deref)
 857                 (*session->deref)(session);
 858
 859         l2tp_session_dec_refcount(session);
 860 }
 861 EXPORT_SYMBOL(l2tp_recv_common);
 862
 863 /* Drop skbs from the session's reorder_q
 864  */
 865 int l2tp_session_queue_purge(struct l2tp_session *session)
 866 {
 867         struct sk_buff *skb = NULL;
 868         BUG_ON(!session);
 869         BUG_ON(session->magic != L2TP_SESSION_MAGIC);
 870         while ((skb = skb_dequeue(&session->reorder_q))) {
 871                 atomic_long_inc(&session->stats.rx_errors);
 872                 kfree_skb(skb);
 873                 if (session->deref)
 874                         (*session->deref)(session);
 875         }
 876         return 0;
 877 }
 878 EXPORT_SYMBOL_GPL(l2tp_session_queue_purge);
 879
 880 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
 881  * here. The skb is not on a list when we get here.
 882  * Returns 0 if the packet was a data packet and was successfully passed on.
 883  * Returns 1 if the packet was not a good data packet and could not be
 884  * forwarded.  All such packets are passed up to userspace to deal with.
 885  */
 886 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
 887                               int (*payload_hook)(struct sk_buff *skb))
 888 {
 889         struct l2tp_session *session = NULL;
 890         unsigned char *ptr, *optr;
 891         u16 hdrflags;
 892         u32 tunnel_id, session_id;
 893         u16 version;
 894         int length;
 895
 896         if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
 897                 goto discard_bad_csum;
 898
 899         /* UDP always verifies the packet length. */
 900         __skb_pull(skb, sizeof(struct udphdr));
 901
 902         /* Short packet? */
 903         if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
 904                 l2tp_info(tunnel, L2TP_MSG_DATA,
 905                           "%s: recv short packet (len=%d)\n",
 906                           tunnel->name, skb->len);
 907                 goto error;
 908         }
 909
 910         /* Trace packet contents, if enabled */
 911         if (tunnel->debug & L2TP_MSG_DATA) {
 912                 length = min(32u, skb->len);
 913                 if (!pskb_may_pull(skb, length))
 914                         goto error;
 915
 916                 pr_debug("%s: recv\n", tunnel->name);
 917                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
 918         }
 919
 920         /* Point to L2TP header */
 921         optr = ptr = skb->data;
 922
 923         /* Get L2TP header flags */
 924         hdrflags = ntohs(*(__be16 *) ptr);
 925
 926         /* Check protocol version */
 927         version = hdrflags & L2TP_HDR_VER_MASK;
 928         if (version != tunnel->version) {
 929                 l2tp_info(tunnel, L2TP_MSG_DATA,
 930                           "%s: recv protocol version mismatch: got %d expected %d\n",
 931                           tunnel->name, version, tunnel->version);
 932                 goto error;
 933         }
 934
 935         /* Get length of L2TP packet */
 936         length = skb->len;
 937
 938         /* If type is control packet, it is handled by userspace. */
 939         if (hdrflags & L2TP_HDRFLAG_T) {
 940                 l2tp_dbg(tunnel, L2TP_MSG_DATA,
 941                          "%s: recv control packet, len=%d\n",
 942                          tunnel->name, length);
 943                 goto error;
 944         }
 945
 946         /* Skip flags */
 947         ptr += 2;
 948
 949         if (tunnel->version == L2TP_HDR_VER_2) {
 950                 /* If length is present, skip it */
 951                 if (hdrflags & L2TP_HDRFLAG_L)
 952                         ptr += 2;
 953
 954                 /* Extract tunnel and session ID */
 955                 tunnel_id = ntohs(*(__be16 *) ptr);
 956                 ptr += 2;
 957                 session_id = ntohs(*(__be16 *) ptr);
 958                 ptr += 2;
 959         } else {
 960                 ptr += 2;       /* skip reserved bits */
 961                 tunnel_id = tunnel->tunnel_id;
 962                 session_id = ntohl(*(__be32 *) ptr);
 963                 ptr += 4;
 964         }
 965
 966         /* Find the session context */
 967         session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
 968         if (!session || !session->recv_skb) {
 969                 /* Not found? Pass to userspace to deal with */
 970                 l2tp_info(tunnel, L2TP_MSG_DATA,
 971                           "%s: no session found (%u/%u). Passing up.\n",
 972                           tunnel->name, tunnel_id, session_id);
 973                 goto error;
 974         }
 975
 976         l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
 977
 978         return 0;
 979
 980 discard_bad_csum:
 981         LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
 982         UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
 983         atomic_long_inc(&tunnel->stats.rx_errors);
 984         kfree_skb(skb);
 985
 986         return 0;
 987
 988 error:
 989         /* Put UDP header back */
 990         __skb_push(skb, sizeof(struct udphdr));
 991
 992         return 1;
 993 }
 994
 995 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
 996  * Return codes:
 997  * 0 : success.
 998  * <0: error
 999  * >0: skb should be passed up to userspace as UDP.
1000  */
1001 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
1002 {
1003         struct l2tp_tunnel *tunnel;
1004
1005         tunnel = l2tp_sock_to_tunnel(sk);
1006         if (tunnel == NULL)
1007                 goto pass_up;
1008
1009         l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
1010                  tunnel->name, skb->len);
1011
1012         if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
1013                 goto pass_up_put;
1014
1015         sock_put(sk);
1016         return 0;
1017
1018 pass_up_put:
1019         sock_put(sk);
1020 pass_up:
1021         return 1;
1022 }
1023 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
1024
1025 /************************************************************************
1026  * Transmit handling
1027  ***********************************************************************/
1028
1029 /* Build an L2TP header for the session into the buffer provided.
1030  */
1031 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
1032 {
1033         struct l2tp_tunnel *tunnel = session->tunnel;
1034         __be16 *bufp = buf;
1035         __be16 *optr = buf;
1036         u16 flags = L2TP_HDR_VER_2;
1037         u32 tunnel_id = tunnel->peer_tunnel_id;
1038         u32 session_id = session->peer_session_id;
1039
1040         if (session->send_seq)
1041                 flags |= L2TP_HDRFLAG_S;
1042
1043         /* Setup L2TP header. */
1044         *bufp++ = htons(flags);
1045         *bufp++ = htons(tunnel_id);
1046         *bufp++ = htons(session_id);
1047         if (session->send_seq) {
1048                 *bufp++ = htons(session->ns);
1049                 *bufp++ = 0;
1050                 session->ns++;
1051                 session->ns &= 0xffff;
1052                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
1053                          session->name, session->ns);
1054         }
1055
1056         return bufp - optr;
1057 }
1058
1059 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
1060 {
1061         struct l2tp_tunnel *tunnel = session->tunnel;
1062         char *bufp = buf;
1063         char *optr = bufp;
1064
1065         /* Setup L2TP header. The header differs slightly for UDP and
1066          * IP encapsulations. For UDP, there is 4 bytes of flags.
1067          */
1068         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
1069                 u16 flags = L2TP_HDR_VER_3;
1070                 *((__be16 *) bufp) = htons(flags);
1071                 bufp += 2;
1072                 *((__be16 *) bufp) = 0;
1073                 bufp += 2;
1074         }
1075
1076         *((__be32 *) bufp) = htonl(session->peer_session_id);
1077         bufp += 4;
1078         if (session->cookie_len) {
1079                 memcpy(bufp, &session->cookie[0], session->cookie_len);
1080                 bufp += session->cookie_len;
1081         }
1082         if (session->l2specific_len) {
1083                 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
1084                         u32 l2h = 0;
1085                         if (session->send_seq) {
1086                                 l2h = 0x40000000 | session->ns;
1087                                 session->ns++;
1088                                 session->ns &= 0xffffff;
1089                                 l2tp_dbg(session, L2TP_MSG_SEQ,
1090                                          "%s: updated ns to %u\n",
1091                                          session->name, session->ns);
1092                         }
1093
1094                         *((__be32 *) bufp) = htonl(l2h);
1095                 }
1096                 bufp += session->l2specific_len;
1097         }
1098         if (session->offset)
1099                 bufp += session->offset;
1100
1101         return bufp - optr;
1102 }
1103
1104 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1105                           struct flowi *fl, size_t data_len)
1106 {
1107         struct l2tp_tunnel *tunnel = session->tunnel;
1108         unsigned int len = skb->len;
1109         int error;
1110
1111         /* Debug */
1112         if (session->send_seq)
1113                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n",
1114                          session->name, data_len, session->ns - 1);
1115         else
1116                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n",
1117                          session->name, data_len);
1118
1119         if (session->debug & L2TP_MSG_DATA) {
1120                 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1121                 unsigned char *datap = skb->data + uhlen;
1122
1123                 pr_debug("%s: xmit\n", session->name);
1124                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1125                                      datap, min_t(size_t, 32, len - uhlen));
1126         }
1127
1128         /* Queue the packet to IP for output */
1129         skb->local_df = 1;
1130 #if IS_ENABLED(CONFIG_IPV6)
1131         if (skb->sk->sk_family == PF_INET6)
1132                 error = inet6_csk_xmit(skb, NULL);
1133         else
1134 #endif
1135                 error = ip_queue_xmit(skb, fl);
1136
1137         /* Update stats */
1138         if (error >= 0) {
1139                 atomic_long_inc(&tunnel->stats.tx_packets);
1140                 atomic_long_add(len, &tunnel->stats.tx_bytes);
1141                 atomic_long_inc(&session->stats.tx_packets);
1142                 atomic_long_add(len, &session->stats.tx_bytes);
1143         } else {
1144                 atomic_long_inc(&tunnel->stats.tx_errors);
1145                 atomic_long_inc(&session->stats.tx_errors);
1146         }
1147
1148         return 0;
1149 }
1150
1151 /* Automatically called when the skb is freed.
1152  */
1153 static void l2tp_sock_wfree(struct sk_buff *skb)
1154 {
1155         sock_put(skb->sk);
1156 }
1157
1158 /* For data skbs that we transmit, we associate with the tunnel socket
1159  * but don't do accounting.
1160  */
1161 static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
1162 {
1163         sock_hold(sk);
1164         skb->sk = sk;
1165         skb->destructor = l2tp_sock_wfree;
1166 }
1167
1168 #if IS_ENABLED(CONFIG_IPV6)
1169 static void l2tp_xmit_ipv6_csum(struct sock *sk, struct sk_buff *skb,
1170                                 int udp_len)
1171 {
1172         struct ipv6_pinfo *np = inet6_sk(sk);
1173         struct udphdr *uh = udp_hdr(skb);
1174
1175         if (!skb_dst(skb) || !skb_dst(skb)->dev ||
1176             !(skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
1177                 __wsum csum = skb_checksum(skb, 0, udp_len, 0);
1178                 skb->ip_summed = CHECKSUM_UNNECESSARY;
1179                 uh->check = csum_ipv6_magic(&np->saddr, &np->daddr, udp_len,
1180                                             IPPROTO_UDP, csum);
1181                 if (uh->check == 0)
1182                         uh->check = CSUM_MANGLED_0;
1183         } else {
1184                 skb->ip_summed = CHECKSUM_PARTIAL;
1185                 skb->csum_start = skb_transport_header(skb) - skb->head;
1186                 skb->csum_offset = offsetof(struct udphdr, check);
1187                 uh->check = ~csum_ipv6_magic(&np->saddr, &np->daddr,
1188                                              udp_len, IPPROTO_UDP, 0);
1189         }
1190 }
1191 #endif
1192
1193 /* If caller requires the skb to have a ppp header, the header must be
1194  * inserted in the skb data before calling this function.
1195  */
1196 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1197 {
1198         int data_len = skb->len;
1199         struct l2tp_tunnel *tunnel = session->tunnel;
1200         struct sock *sk = tunnel->sock;
1201         struct flowi *fl;
1202         struct udphdr *uh;
1203         struct inet_sock *inet;
1204         __wsum csum;
1205         int headroom;
1206         int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1207         int udp_len;
1208         int ret = NET_XMIT_SUCCESS;
1209
1210         /* Check that there's enough headroom in the skb to insert IP,
1211          * UDP and L2TP headers. If not enough, expand it to
1212          * make room. Adjust truesize.
1213          */
1214         headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1215                 uhlen + hdr_len;
1216         if (skb_cow_head(skb, headroom)) {
1217                 kfree_skb(skb);
1218                 return NET_XMIT_DROP;
1219         }
1220
1221         skb_orphan(skb);
1222         /* Setup L2TP header */
1223         session->build_header(session, __skb_push(skb, hdr_len));
1224
1225         /* Reset skb netfilter state */
1226         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1227         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1228                               IPSKB_REROUTED);
1229         nf_reset(skb);
1230
1231         bh_lock_sock(sk);
1232         if (sock_owned_by_user(sk)) {
1233                 kfree_skb(skb);
1234                 ret = NET_XMIT_DROP;
1235                 goto out_unlock;
1236         }
1237
1238         /* Get routing info from the tunnel socket */
1239         skb_dst_drop(skb);
1240         skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
1241
1242         inet = inet_sk(sk);
1243         fl = &inet->cork.fl;
1244         switch (tunnel->encap) {
1245         case L2TP_ENCAPTYPE_UDP:
1246                 /* Setup UDP header */
1247                 __skb_push(skb, sizeof(*uh));
1248                 skb_reset_transport_header(skb);
1249                 uh = udp_hdr(skb);
1250                 uh->source = inet->inet_sport;
1251                 uh->dest = inet->inet_dport;
1252                 udp_len = uhlen + hdr_len + data_len;
1253                 uh->len = htons(udp_len);
1254                 uh->check = 0;
1255
1256                 /* Calculate UDP checksum if configured to do so */
1257 #if IS_ENABLED(CONFIG_IPV6)
1258                 if (sk->sk_family == PF_INET6)
1259                         l2tp_xmit_ipv6_csum(sk, skb, udp_len);
1260                 else
1261 #endif
1262                 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1263                         skb->ip_summed = CHECKSUM_NONE;
1264                 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1265                          (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1266                         skb->ip_summed = CHECKSUM_COMPLETE;
1267                         csum = skb_checksum(skb, 0, udp_len, 0);
1268                         uh->check = csum_tcpudp_magic(inet->inet_saddr,
1269                                                       inet->inet_daddr,
1270                                                       udp_len, IPPROTO_UDP, csum);
1271                         if (uh->check == 0)
1272                                 uh->check = CSUM_MANGLED_0;
1273                 } else {
1274                         skb->ip_summed = CHECKSUM_PARTIAL;
1275                         skb->csum_start = skb_transport_header(skb) - skb->head;
1276                         skb->csum_offset = offsetof(struct udphdr, check);
1277                         uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1278                                                        inet->inet_daddr,
1279                                                        udp_len, IPPROTO_UDP, 0);
1280                 }
1281                 break;
1282
1283         case L2TP_ENCAPTYPE_IP:
1284                 break;
1285         }
1286
1287         l2tp_skb_set_owner_w(skb, sk);
1288
1289         l2tp_xmit_core(session, skb, fl, data_len);
1290 out_unlock:
1291         bh_unlock_sock(sk);
1292
1293         return ret;
1294 }
1295 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1296
1297 /*****************************************************************************
1298  * Tinnel and session create/destroy.
1299  *****************************************************************************/
1300
1301 /* Tunnel socket destruct hook.
1302  * The tunnel context is deleted only when all session sockets have been
1303  * closed.
1304  */
1305 static void l2tp_tunnel_destruct(struct sock *sk)
1306 {
1307         struct l2tp_tunnel *tunnel;
1308         struct l2tp_net *pn;
1309
1310         tunnel = sk->sk_user_data;
1311         if (tunnel == NULL)
1312                 goto end;
1313
1314         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1315
1316
1317         /* Disable udp encapsulation */
1318         switch (tunnel->encap) {
1319         case L2TP_ENCAPTYPE_UDP:
1320                 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1321                 (udp_sk(sk))->encap_type = 0;
1322                 (udp_sk(sk))->encap_rcv = NULL;
1323                 (udp_sk(sk))->encap_destroy = NULL;
1324                 break;
1325         case L2TP_ENCAPTYPE_IP:
1326                 break;
1327         }
1328
1329         /* Remove hooks into tunnel socket */
1330         sk->sk_destruct = tunnel->old_sk_destruct;
1331         sk->sk_user_data = NULL;
1332         tunnel->sock = NULL;
1333
1334         /* Remove the tunnel struct from the tunnel list */
1335         pn = l2tp_pernet(tunnel->l2tp_net);
1336         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1337         list_del_rcu(&tunnel->list);
1338         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1339         atomic_dec(&l2tp_tunnel_count);
1340
1341         l2tp_tunnel_closeall(tunnel);
1342         l2tp_tunnel_dec_refcount(tunnel);
1343
1344         /* Call the original destructor */
1345         if (sk->sk_destruct)
1346                 (*sk->sk_destruct)(sk);
1347 end:
1348         return;
1349 }
1350
1351 /* When the tunnel is closed, all the attached sessions need to go too.
1352  */
1353 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1354 {
1355         int hash;
1356         struct hlist_node *walk;
1357         struct hlist_node *tmp;
1358         struct l2tp_session *session;
1359
1360         BUG_ON(tunnel == NULL);
1361
1362         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1363                   tunnel->name);
1364
1365         write_lock_bh(&tunnel->hlist_lock);
1366         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1367 again:
1368                 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1369                         session = hlist_entry(walk, struct l2tp_session, hlist);
1370
1371                         l2tp_info(session, L2TP_MSG_CONTROL,
1372                                   "%s: closing session\n", session->name);
1373
1374                         hlist_del_init(&session->hlist);
1375
1376                         if (session->ref != NULL)
1377                                 (*session->ref)(session);
1378
1379                         write_unlock_bh(&tunnel->hlist_lock);
1380
1381                         __l2tp_session_unhash(session);
1382                         l2tp_session_queue_purge(session);
1383
1384                         if (session->session_close != NULL)
1385                                 (*session->session_close)(session);
1386
1387                         if (session->deref != NULL)
1388                                 (*session->deref)(session);
1389
1390                         l2tp_session_dec_refcount(session);
1391
1392                         write_lock_bh(&tunnel->hlist_lock);
1393
1394                         /* Now restart from the beginning of this hash
1395                          * chain.  We always remove a session from the
1396                          * list so we are guaranteed to make forward
1397                          * progress.
1398                          */
1399                         goto again;
1400                 }
1401         }
1402         write_unlock_bh(&tunnel->hlist_lock);
1403 }
1404 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
1405
1406 /* Tunnel socket destroy hook for UDP encapsulation */
1407 static void l2tp_udp_encap_destroy(struct sock *sk)
1408 {
1409         struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
1410         if (tunnel) {
1411                 l2tp_tunnel_closeall(tunnel);
1412                 sock_put(sk);
1413         }
1414 }
1415
1416 /* Really kill the tunnel.
1417  * Come here only when all sessions have been cleared from the tunnel.
1418  */
1419 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1420 {
1421         BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1422         BUG_ON(tunnel->sock != NULL);
1423         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name);
1424         kfree_rcu(tunnel, rcu);
1425 }
1426
1427 /* Workqueue tunnel deletion function */
1428 static void l2tp_tunnel_del_work(struct work_struct *work)
1429 {
1430         struct l2tp_tunnel *tunnel = NULL;
1431         struct socket *sock = NULL;
1432         struct sock *sk = NULL;
1433
1434         tunnel = container_of(work, struct l2tp_tunnel, del_work);
1435         sk = l2tp_tunnel_sock_lookup(tunnel);
1436         if (!sk)
1437                 return;
1438
1439         sock = sk->sk_socket;
1440
1441         /* If the tunnel socket was created by userspace, then go through the
1442          * inet layer to shut the socket down, and let userspace close it.
1443          * Otherwise, if we created the socket directly within the kernel, use
1444          * the sk API to release it here.
1445          * In either case the tunnel resources are freed in the socket
1446          * destructor when the tunnel socket goes away.
1447          */
1448         if (tunnel->fd >= 0) {
1449                 if (sock)
1450                         inet_shutdown(sock, 2);
1451         } else {
1452                 if (sock)
1453                         kernel_sock_shutdown(sock, SHUT_RDWR);
1454                 sk_release_kernel(sk);
1455         }
1456
1457         l2tp_tunnel_sock_put(sk);
1458 }
1459
1460 /* Create a socket for the tunnel, if one isn't set up by
1461  * userspace. This is used for static tunnels where there is no
1462  * managing L2TP daemon.
1463  *
1464  * Since we don't want these sockets to keep a namespace alive by
1465  * themselves, we drop the socket's namespace refcount after creation.
1466  * These sockets are freed when the namespace exits using the pernet
1467  * exit hook.
1468  */
1469 static int l2tp_tunnel_sock_create(struct net *net,
1470                                 u32 tunnel_id,
1471                                 u32 peer_tunnel_id,
1472                                 struct l2tp_tunnel_cfg *cfg,
1473                                 struct socket **sockp)
1474 {
1475         int err = -EINVAL;
1476         struct socket *sock = NULL;
1477         struct sockaddr_in udp_addr = {0};
1478         struct sockaddr_l2tpip ip_addr = {0};
1479 #if IS_ENABLED(CONFIG_IPV6)
1480         struct sockaddr_in6 udp6_addr = {0};
1481         struct sockaddr_l2tpip6 ip6_addr = {0};
1482 #endif
1483
1484         switch (cfg->encap) {
1485         case L2TP_ENCAPTYPE_UDP:
1486 #if IS_ENABLED(CONFIG_IPV6)
1487                 if (cfg->local_ip6 && cfg->peer_ip6) {
1488                         err = sock_create_kern(AF_INET6, SOCK_DGRAM, 0, &sock);
1489                         if (err < 0)
1490                                 goto out;
1491
1492                         sk_change_net(sock->sk, net);
1493
1494                         udp6_addr.sin6_family = AF_INET6;
1495                         memcpy(&udp6_addr.sin6_addr, cfg->local_ip6,
1496                                sizeof(udp6_addr.sin6_addr));
1497                         udp6_addr.sin6_port = htons(cfg->local_udp_port);
1498                         err = kernel_bind(sock, (struct sockaddr *) &udp6_addr,
1499                                           sizeof(udp6_addr));
1500                         if (err < 0)
1501                                 goto out;
1502
1503                         udp6_addr.sin6_family = AF_INET6;
1504                         memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6,
1505                                sizeof(udp6_addr.sin6_addr));
1506                         udp6_addr.sin6_port = htons(cfg->peer_udp_port);
1507                         err = kernel_connect(sock,
1508                                              (struct sockaddr *) &udp6_addr,
1509                                              sizeof(udp6_addr), 0);
1510                         if (err < 0)
1511                                 goto out;
1512                 } else
1513 #endif
1514                 {
1515                         err = sock_create_kern(AF_INET, SOCK_DGRAM, 0, &sock);
1516                         if (err < 0)
1517                                 goto out;
1518
1519                         sk_change_net(sock->sk, net);
1520
1521                         udp_addr.sin_family = AF_INET;
1522                         udp_addr.sin_addr = cfg->local_ip;
1523                         udp_addr.sin_port = htons(cfg->local_udp_port);
1524                         err = kernel_bind(sock, (struct sockaddr *) &udp_addr,
1525                                           sizeof(udp_addr));
1526                         if (err < 0)
1527                                 goto out;
1528
1529                         udp_addr.sin_family = AF_INET;
1530                         udp_addr.sin_addr = cfg->peer_ip;
1531                         udp_addr.sin_port = htons(cfg->peer_udp_port);
1532                         err = kernel_connect(sock,
1533                                              (struct sockaddr *) &udp_addr,
1534                                              sizeof(udp_addr), 0);
1535                         if (err < 0)
1536                                 goto out;
1537                 }
1538
1539                 if (!cfg->use_udp_checksums)
1540                         sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1541
1542                 break;
1543
1544         case L2TP_ENCAPTYPE_IP:
1545 #if IS_ENABLED(CONFIG_IPV6)
1546                 if (cfg->local_ip6 && cfg->peer_ip6) {
1547                         err = sock_create_kern(AF_INET6, SOCK_DGRAM,
1548                                           IPPROTO_L2TP, &sock);
1549                         if (err < 0)
1550                                 goto out;
1551
1552                         sk_change_net(sock->sk, net);
1553
1554                         ip6_addr.l2tp_family = AF_INET6;
1555                         memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1556                                sizeof(ip6_addr.l2tp_addr));
1557                         ip6_addr.l2tp_conn_id = tunnel_id;
1558                         err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1559                                           sizeof(ip6_addr));
1560                         if (err < 0)
1561                                 goto out;
1562
1563                         ip6_addr.l2tp_family = AF_INET6;
1564                         memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1565                                sizeof(ip6_addr.l2tp_addr));
1566                         ip6_addr.l2tp_conn_id = peer_tunnel_id;
1567                         err = kernel_connect(sock,
1568                                              (struct sockaddr *) &ip6_addr,
1569                                              sizeof(ip6_addr), 0);
1570                         if (err < 0)
1571                                 goto out;
1572                 } else
1573 #endif
1574                 {
1575                         err = sock_create_kern(AF_INET, SOCK_DGRAM,
1576                                           IPPROTO_L2TP, &sock);
1577                         if (err < 0)
1578                                 goto out;
1579
1580                         sk_change_net(sock->sk, net);
1581
1582                         ip_addr.l2tp_family = AF_INET;
1583                         ip_addr.l2tp_addr = cfg->local_ip;
1584                         ip_addr.l2tp_conn_id = tunnel_id;
1585                         err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1586                                           sizeof(ip_addr));
1587                         if (err < 0)
1588                                 goto out;
1589
1590                         ip_addr.l2tp_family = AF_INET;
1591                         ip_addr.l2tp_addr = cfg->peer_ip;
1592                         ip_addr.l2tp_conn_id = peer_tunnel_id;
1593                         err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1594                                              sizeof(ip_addr), 0);
1595                         if (err < 0)
1596                                 goto out;
1597                 }
1598                 break;
1599
1600         default:
1601                 goto out;
1602         }
1603
1604 out:
1605         *sockp = sock;
1606         if ((err < 0) && sock) {
1607                 kernel_sock_shutdown(sock, SHUT_RDWR);
1608                 sk_release_kernel(sock->sk);
1609                 *sockp = NULL;
1610         }
1611
1612         return err;
1613 }
1614
1615 static struct lock_class_key l2tp_socket_class;
1616
1617 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)
1618 {
1619         struct l2tp_tunnel *tunnel = NULL;
1620         int err;
1621         struct socket *sock = NULL;
1622         struct sock *sk = NULL;
1623         struct l2tp_net *pn;
1624         enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1625
1626         /* Get the tunnel socket from the fd, which was opened by
1627          * the userspace L2TP daemon. If not specified, create a
1628          * kernel socket.
1629          */
1630         if (fd < 0) {
1631                 err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id,
1632                                 cfg, &sock);
1633                 if (err < 0)
1634                         goto err;
1635         } else {
1636                 sock = sockfd_lookup(fd, &err);
1637                 if (!sock) {
1638                         pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n",
1639                                tunnel_id, fd, err);
1640                         err = -EBADF;
1641                         goto err;
1642                 }
1643
1644                 /* Reject namespace mismatches */
1645                 if (!net_eq(sock_net(sock->sk), net)) {
1646                         pr_err("tunl %u: netns mismatch\n", tunnel_id);
1647                         err = -EINVAL;
1648                         goto err;
1649                 }
1650         }
1651
1652         sk = sock->sk;
1653
1654         if (cfg != NULL)
1655                 encap = cfg->encap;
1656
1657         /* Quick sanity checks */
1658         switch (encap) {
1659         case L2TP_ENCAPTYPE_UDP:
1660                 err = -EPROTONOSUPPORT;
1661                 if (sk->sk_protocol != IPPROTO_UDP) {
1662                         pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1663                                tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1664                         goto err;
1665                 }
1666                 break;
1667         case L2TP_ENCAPTYPE_IP:
1668                 err = -EPROTONOSUPPORT;
1669                 if (sk->sk_protocol != IPPROTO_L2TP) {
1670                         pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1671                                tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1672                         goto err;
1673                 }
1674                 break;
1675         }
1676
1677         /* Check if this socket has already been prepped */
1678         tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
1679         if (tunnel != NULL) {
1680                 /* This socket has already been prepped */
1681                 err = -EBUSY;
1682                 goto err;
1683         }
1684
1685         tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1686         if (tunnel == NULL) {
1687                 err = -ENOMEM;
1688                 goto err;
1689         }
1690
1691         tunnel->version = version;
1692         tunnel->tunnel_id = tunnel_id;
1693         tunnel->peer_tunnel_id = peer_tunnel_id;
1694         tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1695
1696         tunnel->magic = L2TP_TUNNEL_MAGIC;
1697         sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1698         rwlock_init(&tunnel->hlist_lock);
1699
1700         /* The net we belong to */
1701         tunnel->l2tp_net = net;
1702         pn = l2tp_pernet(net);
1703
1704         if (cfg != NULL)
1705                 tunnel->debug = cfg->debug;
1706
1707         /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1708         tunnel->encap = encap;
1709         if (encap == L2TP_ENCAPTYPE_UDP) {
1710                 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1711                 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1712                 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1713                 udp_sk(sk)->encap_destroy = l2tp_udp_encap_destroy;
1714 #if IS_ENABLED(CONFIG_IPV6)
1715                 if (sk->sk_family == PF_INET6)
1716                         udpv6_encap_enable();
1717                 else
1718 #endif
1719                 udp_encap_enable();
1720         }
1721
1722         sk->sk_user_data = tunnel;
1723
1724         /* Hook on the tunnel socket destructor so that we can cleanup
1725          * if the tunnel socket goes away.
1726          */
1727         tunnel->old_sk_destruct = sk->sk_destruct;
1728         sk->sk_destruct = &l2tp_tunnel_destruct;
1729         tunnel->sock = sk;
1730         tunnel->fd = fd;
1731         lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
1732
1733         sk->sk_allocation = GFP_ATOMIC;
1734
1735         /* Init delete workqueue struct */
1736         INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
1737
1738         /* Add tunnel to our list */
1739         INIT_LIST_HEAD(&tunnel->list);
1740         atomic_inc(&l2tp_tunnel_count);
1741
1742         /* Bump the reference count. The tunnel context is deleted
1743          * only when this drops to zero. Must be done before list insertion
1744          */
1745         l2tp_tunnel_inc_refcount(tunnel);
1746         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1747         list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1748         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1749
1750         err = 0;
1751 err:
1752         if (tunnelp)
1753                 *tunnelp = tunnel;
1754
1755         /* If tunnel's socket was created by the kernel, it doesn't
1756          *  have a file.
1757          */
1758         if (sock && sock->file)
1759                 sockfd_put(sock);
1760
1761         return err;
1762 }
1763 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1764
1765 /* This function is used by the netlink TUNNEL_DELETE command.
1766  */
1767 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1768 {
1769         l2tp_tunnel_closeall(tunnel);
1770         return (false == queue_work(l2tp_wq, &tunnel->del_work));
1771 }
1772 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1773
1774 /* Really kill the session.
1775  */
1776 void l2tp_session_free(struct l2tp_session *session)
1777 {
1778         struct l2tp_tunnel *tunnel = session->tunnel;
1779
1780         BUG_ON(atomic_read(&session->ref_count) != 0);
1781
1782         if (tunnel) {
1783                 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1784                 if (session->session_id != 0)
1785                         atomic_dec(&l2tp_session_count);
1786                 sock_put(tunnel->sock);
1787                 session->tunnel = NULL;
1788                 l2tp_tunnel_dec_refcount(tunnel);
1789         }
1790
1791         kfree(session);
1792
1793         return;
1794 }
1795 EXPORT_SYMBOL_GPL(l2tp_session_free);
1796
1797 /* Remove an l2tp session from l2tp_core's hash lists.
1798  * Provides a tidyup interface for pseudowire code which can't just route all
1799  * shutdown via. l2tp_session_delete and a pseudowire-specific session_close
1800  * callback.
1801  */
1802 void __l2tp_session_unhash(struct l2tp_session *session)
1803 {
1804         struct l2tp_tunnel *tunnel = session->tunnel;
1805
1806         /* Remove the session from core hashes */
1807         if (tunnel) {
1808                 /* Remove from the per-tunnel hash */
1809                 write_lock_bh(&tunnel->hlist_lock);
1810                 hlist_del_init(&session->hlist);
1811                 write_unlock_bh(&tunnel->hlist_lock);
1812
1813                 /* For L2TPv3 we have a per-net hash: remove from there, too */
1814                 if (tunnel->version != L2TP_HDR_VER_2) {
1815                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1816                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1817                         hlist_del_init_rcu(&session->global_hlist);
1818                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1819                         synchronize_rcu();
1820                 }
1821         }
1822 }
1823 EXPORT_SYMBOL_GPL(__l2tp_session_unhash);
1824
1825 /* This function is used by the netlink SESSION_DELETE command and by
1826    pseudowire modules.
1827  */
1828 int l2tp_session_delete(struct l2tp_session *session)
1829 {
1830         if (session->ref)
1831                 (*session->ref)(session);
1832         __l2tp_session_unhash(session);
1833         l2tp_session_queue_purge(session);
1834         if (session->session_close != NULL)
1835                 (*session->session_close)(session);
1836         if (session->deref)
1837                 (*session->deref)(session);
1838         l2tp_session_dec_refcount(session);
1839         return 0;
1840 }
1841 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1842
1843 /* We come here whenever a session's send_seq, cookie_len or
1844  * l2specific_len parameters are set.
1845  */
1846 static void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1847 {
1848         if (version == L2TP_HDR_VER_2) {
1849                 session->hdr_len = 6;
1850                 if (session->send_seq)
1851                         session->hdr_len += 4;
1852         } else {
1853                 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1854                 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1855                         session->hdr_len += 4;
1856         }
1857
1858 }
1859
1860 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)
1861 {
1862         struct l2tp_session *session;
1863
1864         session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1865         if (session != NULL) {
1866                 session->magic = L2TP_SESSION_MAGIC;
1867                 session->tunnel = tunnel;
1868
1869                 session->session_id = session_id;
1870                 session->peer_session_id = peer_session_id;
1871                 session->nr = 0;
1872                 if (tunnel->version == L2TP_HDR_VER_2)
1873                         session->nr_max = 0xffff;
1874                 else
1875                         session->nr_max = 0xffffff;
1876                 session->nr_window_size = session->nr_max / 2;
1877                 session->nr_oos_count_max = 4;
1878
1879                 /* Use NR of first received packet */
1880                 session->reorder_skip = 1;
1881
1882                 sprintf(&session->name[0], "sess %u/%u",
1883                         tunnel->tunnel_id, session->session_id);
1884
1885                 skb_queue_head_init(&session->reorder_q);
1886
1887                 INIT_HLIST_NODE(&session->hlist);
1888                 INIT_HLIST_NODE(&session->global_hlist);
1889
1890                 /* Inherit debug options from tunnel */
1891                 session->debug = tunnel->debug;
1892
1893                 if (cfg) {
1894                         session->pwtype = cfg->pw_type;
1895                         session->debug = cfg->debug;
1896                         session->mtu = cfg->mtu;
1897                         session->mru = cfg->mru;
1898                         session->send_seq = cfg->send_seq;
1899                         session->recv_seq = cfg->recv_seq;
1900                         session->lns_mode = cfg->lns_mode;
1901                         session->reorder_timeout = cfg->reorder_timeout;
1902                         session->offset = cfg->offset;
1903                         session->l2specific_type = cfg->l2specific_type;
1904                         session->l2specific_len = cfg->l2specific_len;
1905                         session->cookie_len = cfg->cookie_len;
1906                         memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1907                         session->peer_cookie_len = cfg->peer_cookie_len;
1908                         memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1909                 }
1910
1911                 if (tunnel->version == L2TP_HDR_VER_2)
1912                         session->build_header = l2tp_build_l2tpv2_header;
1913                 else
1914                         session->build_header = l2tp_build_l2tpv3_header;
1915
1916                 l2tp_session_set_header_len(session, tunnel->version);
1917
1918                 /* Bump the reference count. The session context is deleted
1919                  * only when this drops to zero.
1920                  */
1921                 l2tp_session_inc_refcount(session);
1922                 l2tp_tunnel_inc_refcount(tunnel);
1923
1924                 /* Ensure tunnel socket isn't deleted */
1925                 sock_hold(tunnel->sock);
1926
1927                 /* Add session to the tunnel's hash list */
1928                 write_lock_bh(&tunnel->hlist_lock);
1929                 hlist_add_head(&session->hlist,
1930                                l2tp_session_id_hash(tunnel, session_id));
1931                 write_unlock_bh(&tunnel->hlist_lock);
1932
1933                 /* And to the global session list if L2TPv3 */
1934                 if (tunnel->version != L2TP_HDR_VER_2) {
1935                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1936
1937                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1938                         hlist_add_head_rcu(&session->global_hlist,
1939                                            l2tp_session_id_hash_2(pn, session_id));
1940                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1941                 }
1942
1943                 /* Ignore management session in session count value */
1944                 if (session->session_id != 0)
1945                         atomic_inc(&l2tp_session_count);
1946         }
1947
1948         return session;
1949 }
1950 EXPORT_SYMBOL_GPL(l2tp_session_create);
1951
1952 /*****************************************************************************
1953  * Init and cleanup
1954  *****************************************************************************/
1955
1956 static __net_init int l2tp_init_net(struct net *net)
1957 {
1958         struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1959         int hash;
1960
1961         INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1962         spin_lock_init(&pn->l2tp_tunnel_list_lock);
1963
1964         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1965                 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1966
1967         spin_lock_init(&pn->l2tp_session_hlist_lock);
1968
1969         return 0;
1970 }
1971
1972 static __net_exit void l2tp_exit_net(struct net *net)
1973 {
1974         struct l2tp_net *pn = l2tp_pernet(net);
1975         struct l2tp_tunnel *tunnel = NULL;
1976
1977         rcu_read_lock_bh();
1978         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
1979                 (void)l2tp_tunnel_delete(tunnel);
1980         }
1981         rcu_read_unlock_bh();
1982 }
1983
1984 static struct pernet_operations l2tp_net_ops = {
1985         .init = l2tp_init_net,
1986         .exit = l2tp_exit_net,
1987         .id   = &l2tp_net_id,
1988         .size = sizeof(struct l2tp_net),
1989 };
1990
1991 static int __init l2tp_init(void)
1992 {
1993         int rc = 0;
1994
1995         rc = register_pernet_device(&l2tp_net_ops);
1996         if (rc)
1997                 goto out;
1998
1999         l2tp_wq = alloc_workqueue("l2tp", WQ_NON_REENTRANT | WQ_UNBOUND, 0);
2000         if (!l2tp_wq) {
2001                 pr_err("alloc_workqueue failed\n");
2002                 rc = -ENOMEM;
2003                 goto out;
2004         }
2005
2006         pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
2007
2008 out:
2009         return rc;
2010 }
2011
2012 static void __exit l2tp_exit(void)
2013 {
2014         unregister_pernet_device(&l2tp_net_ops);
2015         if (l2tp_wq) {
2016                 destroy_workqueue(l2tp_wq);
2017                 l2tp_wq = NULL;
2018         }
2019 }
2020
2021 module_init(l2tp_init);
2022 module_exit(l2tp_exit);
2023
2024 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
2025 MODULE_DESCRIPTION("L2TP core");
2026 MODULE_LICENSE("GPL");
2027 MODULE_VERSION(L2TP_DRV_VERSION);
2028