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 l2tp_tunnel *tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
 500         struct udphdr *uh = udp_hdr(skb);
 501         u16 ulen = ntohs(uh->len);
 502         __wsum psum;
 503
 504         if (sk->sk_no_check || skb_csum_unnecessary(skb))
 505                 return 0;
 506
 507 #if IS_ENABLED(CONFIG_IPV6)
 508         if (sk->sk_family == PF_INET6 && !tunnel->v4mapped) {
 509                 if (!uh->check) {
 510                         LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n");
 511                         return 1;
 512                 }
 513                 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
 514                     !csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
 515                                      &ipv6_hdr(skb)->daddr, ulen,
 516                                      IPPROTO_UDP, skb->csum)) {
 517                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 518                         return 0;
 519                 }
 520                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
 521                                                          &ipv6_hdr(skb)->daddr,
 522                                                          skb->len, IPPROTO_UDP,
 523                                                          0));
 524         } else
 525 #endif
 526         {
 527                 struct inet_sock *inet;
 528                 if (!uh->check)
 529                         return 0;
 530                 inet = inet_sk(sk);
 531                 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr,
 532                                           ulen, IPPROTO_UDP, 0);
 533
 534                 if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
 535                     !csum_fold(csum_add(psum, skb->csum)))
 536                         return 0;
 537                 skb->csum = psum;
 538         }
 539
 540         return __skb_checksum_complete(skb);
 541 }
 542
 543 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr)
 544 {
 545         u32 nws;
 546
 547         if (nr >= session->nr)
 548                 nws = nr - session->nr;
 549         else
 550                 nws = (session->nr_max + 1) - (session->nr - nr);
 551
 552         return nws < session->nr_window_size;
 553 }
 554
 555 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if
 556  * acceptable, else non-zero.
 557  */
 558 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
 559 {
 560         if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) {
 561                 /* Packet sequence number is outside allowed window.
 562                  * Discard it.
 563                  */
 564                 l2tp_dbg(session, L2TP_MSG_SEQ,
 565                          "%s: pkt %u len %d discarded, outside window, nr=%u\n",
 566                          session->name, L2TP_SKB_CB(skb)->ns,
 567                          L2TP_SKB_CB(skb)->length, session->nr);
 568                 goto discard;
 569         }
 570
 571         if (session->reorder_timeout != 0) {
 572                 /* Packet reordering enabled. Add skb to session's
 573                  * reorder queue, in order of ns.
 574                  */
 575                 l2tp_recv_queue_skb(session, skb);
 576                 goto out;
 577         }
 578
 579         /* Packet reordering disabled. Discard out-of-sequence packets, while
 580          * tracking the number if in-sequence packets after the first OOS packet
 581          * is seen. After nr_oos_count_max in-sequence packets, reset the
 582          * sequence number to re-enable packet reception.
 583          */
 584         if (L2TP_SKB_CB(skb)->ns == session->nr) {
 585                 skb_queue_tail(&session->reorder_q, skb);
 586         } else {
 587                 u32 nr_oos = L2TP_SKB_CB(skb)->ns;
 588                 u32 nr_next = (session->nr_oos + 1) & session->nr_max;
 589
 590                 if (nr_oos == nr_next)
 591                         session->nr_oos_count++;
 592                 else
 593                         session->nr_oos_count = 0;
 594
 595                 session->nr_oos = nr_oos;
 596                 if (session->nr_oos_count > session->nr_oos_count_max) {
 597                         session->reorder_skip = 1;
 598                         l2tp_dbg(session, L2TP_MSG_SEQ,
 599                                  "%s: %d oos packets received. Resetting sequence numbers\n",
 600                                  session->name, session->nr_oos_count);
 601                 }
 602                 if (!session->reorder_skip) {
 603                         atomic_long_inc(&session->stats.rx_seq_discards);
 604                         l2tp_dbg(session, L2TP_MSG_SEQ,
 605                                  "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
 606                                  session->name, L2TP_SKB_CB(skb)->ns,
 607                                  L2TP_SKB_CB(skb)->length, session->nr,
 608                                  skb_queue_len(&session->reorder_q));
 609                         goto discard;
 610                 }
 611                 skb_queue_tail(&session->reorder_q, skb);
 612         }
 613
 614 out:
 615         return 0;
 616
 617 discard:
 618         return 1;
 619 }
 620
 621 /* Do receive processing of L2TP data frames. We handle both L2TPv2
 622  * and L2TPv3 data frames here.
 623  *
 624  * L2TPv2 Data Message Header
 625  *
 626  *  0                   1                   2                   3
 627  *  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
 628  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 629  * |T|L|x|x|S|x|O|P|x|x|x|x|  Ver  |          Length (opt)         |
 630  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 631  * |           Tunnel ID           |           Session ID          |
 632  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 633  * |             Ns (opt)          |             Nr (opt)          |
 634  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 635  * |      Offset Size (opt)        |    Offset pad... (opt)
 636  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 637  *
 638  * Data frames are marked by T=0. All other fields are the same as
 639  * those in L2TP control frames.
 640  *
 641  * L2TPv3 Data Message Header
 642  *
 643  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 644  * |                      L2TP Session Header                      |
 645  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 646  * |                      L2-Specific Sublayer                     |
 647  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 648  * |                        Tunnel Payload                      ...
 649  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 650  *
 651  * L2TPv3 Session Header Over IP
 652  *
 653  *  0                   1                   2                   3
 654  *  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
 655  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 656  * |                           Session ID                          |
 657  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 658  * |               Cookie (optional, maximum 64 bits)...
 659  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 660  *                                                                 |
 661  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 662  *
 663  * L2TPv3 L2-Specific Sublayer Format
 664  *
 665  *  0                   1                   2                   3
 666  *  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
 667  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 668  * |x|S|x|x|x|x|x|x|              Sequence Number                  |
 669  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 670  *
 671  * Cookie value, sublayer format and offset (pad) are negotiated with
 672  * the peer when the session is set up. Unlike L2TPv2, we do not need
 673  * to parse the packet header to determine if optional fields are
 674  * present.
 675  *
 676  * Caller must already have parsed the frame and determined that it is
 677  * a data (not control) frame before coming here. Fields up to the
 678  * session-id have already been parsed and ptr points to the data
 679  * after the session-id.
 680  */
 681 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 682                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 683                       int length, int (*payload_hook)(struct sk_buff *skb))
 684 {
 685         struct l2tp_tunnel *tunnel = session->tunnel;
 686         int offset;
 687         u32 ns, nr;
 688
 689         /* The ref count is increased since we now hold a pointer to
 690          * the session. Take care to decrement the refcnt when exiting
 691          * this function from now on...
 692          */
 693         l2tp_session_inc_refcount(session);
 694         if (session->ref)
 695                 (*session->ref)(session);
 696
 697         /* Parse and check optional cookie */
 698         if (session->peer_cookie_len > 0) {
 699                 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
 700                         l2tp_info(tunnel, L2TP_MSG_DATA,
 701                                   "%s: cookie mismatch (%u/%u). Discarding.\n",
 702                                   tunnel->name, tunnel->tunnel_id,
 703                                   session->session_id);
 704                         atomic_long_inc(&session->stats.rx_cookie_discards);
 705                         goto discard;
 706                 }
 707                 ptr += session->peer_cookie_len;
 708         }
 709
 710         /* Handle the optional sequence numbers. Sequence numbers are
 711          * in different places for L2TPv2 and L2TPv3.
 712          *
 713          * If we are the LAC, enable/disable sequence numbers under
 714          * the control of the LNS.  If no sequence numbers present but
 715          * we were expecting them, discard frame.
 716          */
 717         ns = nr = 0;
 718         L2TP_SKB_CB(skb)->has_seq = 0;
 719         if (tunnel->version == L2TP_HDR_VER_2) {
 720                 if (hdrflags & L2TP_HDRFLAG_S) {
 721                         ns = ntohs(*(__be16 *) ptr);
 722                         ptr += 2;
 723                         nr = ntohs(*(__be16 *) ptr);
 724                         ptr += 2;
 725
 726                         /* Store L2TP info in the skb */
 727                         L2TP_SKB_CB(skb)->ns = ns;
 728                         L2TP_SKB_CB(skb)->has_seq = 1;
 729
 730                         l2tp_dbg(session, L2TP_MSG_SEQ,
 731                                  "%s: recv data ns=%u, nr=%u, session nr=%u\n",
 732                                  session->name, ns, nr, session->nr);
 733                 }
 734         } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
 735                 u32 l2h = ntohl(*(__be32 *) ptr);
 736
 737                 if (l2h & 0x40000000) {
 738                         ns = l2h & 0x00ffffff;
 739
 740                         /* Store L2TP info in the skb */
 741                         L2TP_SKB_CB(skb)->ns = ns;
 742                         L2TP_SKB_CB(skb)->has_seq = 1;
 743
 744                         l2tp_dbg(session, L2TP_MSG_SEQ,
 745                                  "%s: recv data ns=%u, session nr=%u\n",
 746                                  session->name, ns, session->nr);
 747                 }
 748         }
 749
 750         /* Advance past L2-specific header, if present */
 751         ptr += session->l2specific_len;
 752
 753         if (L2TP_SKB_CB(skb)->has_seq) {
 754                 /* Received a packet with sequence numbers. If we're the LNS,
 755                  * check if we sre sending sequence numbers and if not,
 756                  * configure it so.
 757                  */
 758                 if ((!session->lns_mode) && (!session->send_seq)) {
 759                         l2tp_info(session, L2TP_MSG_SEQ,
 760                                   "%s: requested to enable seq numbers by LNS\n",
 761                                   session->name);
 762                         session->send_seq = -1;
 763                         l2tp_session_set_header_len(session, tunnel->version);
 764                 }
 765         } else {
 766                 /* No sequence numbers.
 767                  * If user has configured mandatory sequence numbers, discard.
 768                  */
 769                 if (session->recv_seq) {
 770                         l2tp_warn(session, L2TP_MSG_SEQ,
 771                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 772                                   session->name);
 773                         atomic_long_inc(&session->stats.rx_seq_discards);
 774                         goto discard;
 775                 }
 776
 777                 /* If we're the LAC and we're sending sequence numbers, the
 778                  * LNS has requested that we no longer send sequence numbers.
 779                  * If we're the LNS and we're sending sequence numbers, the
 780                  * LAC is broken. Discard the frame.
 781                  */
 782                 if ((!session->lns_mode) && (session->send_seq)) {
 783                         l2tp_info(session, L2TP_MSG_SEQ,
 784                                   "%s: requested to disable seq numbers by LNS\n",
 785                                   session->name);
 786                         session->send_seq = 0;
 787                         l2tp_session_set_header_len(session, tunnel->version);
 788                 } else if (session->send_seq) {
 789                         l2tp_warn(session, L2TP_MSG_SEQ,
 790                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 791                                   session->name);
 792                         atomic_long_inc(&session->stats.rx_seq_discards);
 793                         goto discard;
 794                 }
 795         }
 796
 797         /* Session data offset is handled differently for L2TPv2 and
 798          * L2TPv3. For L2TPv2, there is an optional 16-bit value in
 799          * the header. For L2TPv3, the offset is negotiated using AVPs
 800          * in the session setup control protocol.
 801          */
 802         if (tunnel->version == L2TP_HDR_VER_2) {
 803                 /* If offset bit set, skip it. */
 804                 if (hdrflags & L2TP_HDRFLAG_O) {
 805                         offset = ntohs(*(__be16 *)ptr);
 806                         ptr += 2 + offset;
 807                 }
 808         } else
 809                 ptr += session->offset;
 810
 811         offset = ptr - optr;
 812         if (!pskb_may_pull(skb, offset))
 813                 goto discard;
 814
 815         __skb_pull(skb, offset);
 816
 817         /* If caller wants to process the payload before we queue the
 818          * packet, do so now.
 819          */
 820         if (payload_hook)
 821                 if ((*payload_hook)(skb))
 822                         goto discard;
 823
 824         /* Prepare skb for adding to the session's reorder_q.  Hold
 825          * packets for max reorder_timeout or 1 second if not
 826          * reordering.
 827          */
 828         L2TP_SKB_CB(skb)->length = length;
 829         L2TP_SKB_CB(skb)->expires = jiffies +
 830                 (session->reorder_timeout ? session->reorder_timeout : HZ);
 831
 832         /* Add packet to the session's receive queue. Reordering is done here, if
 833          * enabled. Saved L2TP protocol info is stored in skb->sb[].
 834          */
 835         if (L2TP_SKB_CB(skb)->has_seq) {
 836                 if (l2tp_recv_data_seq(session, skb))
 837                         goto discard;
 838         } else {
 839                 /* No sequence numbers. Add the skb to the tail of the
 840                  * reorder queue. This ensures that it will be
 841                  * delivered after all previous sequenced skbs.
 842                  */
 843                 skb_queue_tail(&session->reorder_q, skb);
 844         }
 845
 846         /* Try to dequeue as many skbs from reorder_q as we can. */
 847         l2tp_recv_dequeue(session);
 848
 849         l2tp_session_dec_refcount(session);
 850
 851         return;
 852
 853 discard:
 854         atomic_long_inc(&session->stats.rx_errors);
 855         kfree_skb(skb);
 856
 857         if (session->deref)
 858                 (*session->deref)(session);
 859
 860         l2tp_session_dec_refcount(session);
 861 }
 862 EXPORT_SYMBOL(l2tp_recv_common);
 863
 864 /* Drop skbs from the session's reorder_q
 865  */
 866 int l2tp_session_queue_purge(struct l2tp_session *session)
 867 {
 868         struct sk_buff *skb = NULL;
 869         BUG_ON(!session);
 870         BUG_ON(session->magic != L2TP_SESSION_MAGIC);
 871         while ((skb = skb_dequeue(&session->reorder_q))) {
 872                 atomic_long_inc(&session->stats.rx_errors);
 873                 kfree_skb(skb);
 874                 if (session->deref)
 875                         (*session->deref)(session);
 876         }
 877         return 0;
 878 }
 879 EXPORT_SYMBOL_GPL(l2tp_session_queue_purge);
 880
 881 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
 882  * here. The skb is not on a list when we get here.
 883  * Returns 0 if the packet was a data packet and was successfully passed on.
 884  * Returns 1 if the packet was not a good data packet and could not be
 885  * forwarded.  All such packets are passed up to userspace to deal with.
 886  */
 887 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
 888                               int (*payload_hook)(struct sk_buff *skb))
 889 {
 890         struct l2tp_session *session = NULL;
 891         unsigned char *ptr, *optr;
 892         u16 hdrflags;
 893         u32 tunnel_id, session_id;
 894         u16 version;
 895         int length;
 896
 897         if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
 898                 goto discard_bad_csum;
 899
 900         /* UDP always verifies the packet length. */
 901         __skb_pull(skb, sizeof(struct udphdr));
 902
 903         /* Short packet? */
 904         if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
 905                 l2tp_info(tunnel, L2TP_MSG_DATA,
 906                           "%s: recv short packet (len=%d)\n",
 907                           tunnel->name, skb->len);
 908                 goto error;
 909         }
 910
 911         /* Trace packet contents, if enabled */
 912         if (tunnel->debug & L2TP_MSG_DATA) {
 913                 length = min(32u, skb->len);
 914                 if (!pskb_may_pull(skb, length))
 915                         goto error;
 916
 917                 pr_debug("%s: recv\n", tunnel->name);
 918                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
 919         }
 920
 921         /* Point to L2TP header */
 922         optr = ptr = skb->data;
 923
 924         /* Get L2TP header flags */
 925         hdrflags = ntohs(*(__be16 *) ptr);
 926
 927         /* Check protocol version */
 928         version = hdrflags & L2TP_HDR_VER_MASK;
 929         if (version != tunnel->version) {
 930                 l2tp_info(tunnel, L2TP_MSG_DATA,
 931                           "%s: recv protocol version mismatch: got %d expected %d\n",
 932                           tunnel->name, version, tunnel->version);
 933                 goto error;
 934         }
 935
 936         /* Get length of L2TP packet */
 937         length = skb->len;
 938
 939         /* If type is control packet, it is handled by userspace. */
 940         if (hdrflags & L2TP_HDRFLAG_T) {
 941                 l2tp_dbg(tunnel, L2TP_MSG_DATA,
 942                          "%s: recv control packet, len=%d\n",
 943                          tunnel->name, length);
 944                 goto error;
 945         }
 946
 947         /* Skip flags */
 948         ptr += 2;
 949
 950         if (tunnel->version == L2TP_HDR_VER_2) {
 951                 /* If length is present, skip it */
 952                 if (hdrflags & L2TP_HDRFLAG_L)
 953                         ptr += 2;
 954
 955                 /* Extract tunnel and session ID */
 956                 tunnel_id = ntohs(*(__be16 *) ptr);
 957                 ptr += 2;
 958                 session_id = ntohs(*(__be16 *) ptr);
 959                 ptr += 2;
 960         } else {
 961                 ptr += 2;       /* skip reserved bits */
 962                 tunnel_id = tunnel->tunnel_id;
 963                 session_id = ntohl(*(__be32 *) ptr);
 964                 ptr += 4;
 965         }
 966
 967         /* Find the session context */
 968         session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
 969         if (!session || !session->recv_skb) {
 970                 /* Not found? Pass to userspace to deal with */
 971                 l2tp_info(tunnel, L2TP_MSG_DATA,
 972                           "%s: no session found (%u/%u). Passing up.\n",
 973                           tunnel->name, tunnel_id, session_id);
 974                 goto error;
 975         }
 976
 977         l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
 978
 979         return 0;
 980
 981 discard_bad_csum:
 982         LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
 983         UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
 984         atomic_long_inc(&tunnel->stats.rx_errors);
 985         kfree_skb(skb);
 986
 987         return 0;
 988
 989 error:
 990         /* Put UDP header back */
 991         __skb_push(skb, sizeof(struct udphdr));
 992
 993         return 1;
 994 }
 995
 996 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
 997  * Return codes:
 998  * 0 : success.
 999  * <0: error
1000  * >0: skb should be passed up to userspace as UDP.
1001  */
1002 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
1003 {
1004         struct l2tp_tunnel *tunnel;
1005
1006         tunnel = l2tp_sock_to_tunnel(sk);
1007         if (tunnel == NULL)
1008                 goto pass_up;
1009
1010         l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
1011                  tunnel->name, skb->len);
1012
1013         if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
1014                 goto pass_up_put;
1015
1016         sock_put(sk);
1017         return 0;
1018
1019 pass_up_put:
1020         sock_put(sk);
1021 pass_up:
1022         return 1;
1023 }
1024 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
1025
1026 /************************************************************************
1027  * Transmit handling
1028  ***********************************************************************/
1029
1030 /* Build an L2TP header for the session into the buffer provided.
1031  */
1032 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
1033 {
1034         struct l2tp_tunnel *tunnel = session->tunnel;
1035         __be16 *bufp = buf;
1036         __be16 *optr = buf;
1037         u16 flags = L2TP_HDR_VER_2;
1038         u32 tunnel_id = tunnel->peer_tunnel_id;
1039         u32 session_id = session->peer_session_id;
1040
1041         if (session->send_seq)
1042                 flags |= L2TP_HDRFLAG_S;
1043
1044         /* Setup L2TP header. */
1045         *bufp++ = htons(flags);
1046         *bufp++ = htons(tunnel_id);
1047         *bufp++ = htons(session_id);
1048         if (session->send_seq) {
1049                 *bufp++ = htons(session->ns);
1050                 *bufp++ = 0;
1051                 session->ns++;
1052                 session->ns &= 0xffff;
1053                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
1054                          session->name, session->ns);
1055         }
1056
1057         return bufp - optr;
1058 }
1059
1060 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
1061 {
1062         struct l2tp_tunnel *tunnel = session->tunnel;
1063         char *bufp = buf;
1064         char *optr = bufp;
1065
1066         /* Setup L2TP header. The header differs slightly for UDP and
1067          * IP encapsulations. For UDP, there is 4 bytes of flags.
1068          */
1069         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
1070                 u16 flags = L2TP_HDR_VER_3;
1071                 *((__be16 *) bufp) = htons(flags);
1072                 bufp += 2;
1073                 *((__be16 *) bufp) = 0;
1074                 bufp += 2;
1075         }
1076
1077         *((__be32 *) bufp) = htonl(session->peer_session_id);
1078         bufp += 4;
1079         if (session->cookie_len) {
1080                 memcpy(bufp, &session->cookie[0], session->cookie_len);
1081                 bufp += session->cookie_len;
1082         }
1083         if (session->l2specific_len) {
1084                 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
1085                         u32 l2h = 0;
1086                         if (session->send_seq) {
1087                                 l2h = 0x40000000 | session->ns;
1088                                 session->ns++;
1089                                 session->ns &= 0xffffff;
1090                                 l2tp_dbg(session, L2TP_MSG_SEQ,
1091                                          "%s: updated ns to %u\n",
1092                                          session->name, session->ns);
1093                         }
1094
1095                         *((__be32 *) bufp) = htonl(l2h);
1096                 }
1097                 bufp += session->l2specific_len;
1098         }
1099         if (session->offset)
1100                 bufp += session->offset;
1101
1102         return bufp - optr;
1103 }
1104
1105 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1106                           struct flowi *fl, size_t data_len)
1107 {
1108         struct l2tp_tunnel *tunnel = session->tunnel;
1109         unsigned int len = skb->len;
1110         int error;
1111
1112         /* Debug */
1113         if (session->send_seq)
1114                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n",
1115                          session->name, data_len, session->ns - 1);
1116         else
1117                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n",
1118                          session->name, data_len);
1119
1120         if (session->debug & L2TP_MSG_DATA) {
1121                 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1122                 unsigned char *datap = skb->data + uhlen;
1123
1124                 pr_debug("%s: xmit\n", session->name);
1125                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1126                                      datap, min_t(size_t, 32, len - uhlen));
1127         }
1128
1129         /* Queue the packet to IP for output */
1130         skb->local_df = 1;
1131 #if IS_ENABLED(CONFIG_IPV6)
1132         if (skb->sk->sk_family == PF_INET6 && !tunnel->v4mapped)
1133                 error = inet6_csk_xmit(skb, NULL);
1134         else
1135 #endif
1136                 error = ip_queue_xmit(skb, fl);
1137
1138         /* Update stats */
1139         if (error >= 0) {
1140                 atomic_long_inc(&tunnel->stats.tx_packets);
1141                 atomic_long_add(len, &tunnel->stats.tx_bytes);
1142                 atomic_long_inc(&session->stats.tx_packets);
1143                 atomic_long_add(len, &session->stats.tx_bytes);
1144         } else {
1145                 atomic_long_inc(&tunnel->stats.tx_errors);
1146                 atomic_long_inc(&session->stats.tx_errors);
1147         }
1148
1149         return 0;
1150 }
1151
1152 /* Automatically called when the skb is freed.
1153  */
1154 static void l2tp_sock_wfree(struct sk_buff *skb)
1155 {
1156         sock_put(skb->sk);
1157 }
1158
1159 /* For data skbs that we transmit, we associate with the tunnel socket
1160  * but don't do accounting.
1161  */
1162 static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
1163 {
1164         sock_hold(sk);
1165         skb->sk = sk;
1166         skb->destructor = l2tp_sock_wfree;
1167 }
1168
1169 #if IS_ENABLED(CONFIG_IPV6)
1170 static void l2tp_xmit_ipv6_csum(struct sock *sk, struct sk_buff *skb,
1171                                 int udp_len)
1172 {
1173         struct ipv6_pinfo *np = inet6_sk(sk);
1174         struct udphdr *uh = udp_hdr(skb);
1175
1176         if (!skb_dst(skb) || !skb_dst(skb)->dev ||
1177             !(skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) {
1178                 __wsum csum = skb_checksum(skb, 0, udp_len, 0);
1179                 skb->ip_summed = CHECKSUM_UNNECESSARY;
1180                 uh->check = csum_ipv6_magic(&np->saddr, &np->daddr, udp_len,
1181                                             IPPROTO_UDP, csum);
1182                 if (uh->check == 0)
1183                         uh->check = CSUM_MANGLED_0;
1184         } else {
1185                 skb->ip_summed = CHECKSUM_PARTIAL;
1186                 skb->csum_start = skb_transport_header(skb) - skb->head;
1187                 skb->csum_offset = offsetof(struct udphdr, check);
1188                 uh->check = ~csum_ipv6_magic(&np->saddr, &np->daddr,
1189                                              udp_len, IPPROTO_UDP, 0);
1190         }
1191 }
1192 #endif
1193
1194 /* If caller requires the skb to have a ppp header, the header must be
1195  * inserted in the skb data before calling this function.
1196  */
1197 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1198 {
1199         int data_len = skb->len;
1200         struct l2tp_tunnel *tunnel = session->tunnel;
1201         struct sock *sk = tunnel->sock;
1202         struct flowi *fl;
1203         struct udphdr *uh;
1204         struct inet_sock *inet;
1205         __wsum csum;
1206         int headroom;
1207         int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1208         int udp_len;
1209         int ret = NET_XMIT_SUCCESS;
1210
1211         /* Check that there's enough headroom in the skb to insert IP,
1212          * UDP and L2TP headers. If not enough, expand it to
1213          * make room. Adjust truesize.
1214          */
1215         headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1216                 uhlen + hdr_len;
1217         if (skb_cow_head(skb, headroom)) {
1218                 kfree_skb(skb);
1219                 return NET_XMIT_DROP;
1220         }
1221
1222         skb_orphan(skb);
1223         /* Setup L2TP header */
1224         session->build_header(session, __skb_push(skb, hdr_len));
1225
1226         /* Reset skb netfilter state */
1227         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1228         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1229                               IPSKB_REROUTED);
1230         nf_reset(skb);
1231
1232         bh_lock_sock(sk);
1233         if (sock_owned_by_user(sk)) {
1234                 kfree_skb(skb);
1235                 ret = NET_XMIT_DROP;
1236                 goto out_unlock;
1237         }
1238
1239         /* Get routing info from the tunnel socket */
1240         skb_dst_drop(skb);
1241         skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
1242
1243         inet = inet_sk(sk);
1244         fl = &inet->cork.fl;
1245         switch (tunnel->encap) {
1246         case L2TP_ENCAPTYPE_UDP:
1247                 /* Setup UDP header */
1248                 __skb_push(skb, sizeof(*uh));
1249                 skb_reset_transport_header(skb);
1250                 uh = udp_hdr(skb);
1251                 uh->source = inet->inet_sport;
1252                 uh->dest = inet->inet_dport;
1253                 udp_len = uhlen + hdr_len + data_len;
1254                 uh->len = htons(udp_len);
1255                 uh->check = 0;
1256
1257                 /* Calculate UDP checksum if configured to do so */
1258 #if IS_ENABLED(CONFIG_IPV6)
1259                 if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
1260                         l2tp_xmit_ipv6_csum(sk, skb, udp_len);
1261                 else
1262 #endif
1263                 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1264                         skb->ip_summed = CHECKSUM_NONE;
1265                 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1266                          (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1267                         skb->ip_summed = CHECKSUM_COMPLETE;
1268                         csum = skb_checksum(skb, 0, udp_len, 0);
1269                         uh->check = csum_tcpudp_magic(inet->inet_saddr,
1270                                                       inet->inet_daddr,
1271                                                       udp_len, IPPROTO_UDP, csum);
1272                         if (uh->check == 0)
1273                                 uh->check = CSUM_MANGLED_0;
1274                 } else {
1275                         skb->ip_summed = CHECKSUM_PARTIAL;
1276                         skb->csum_start = skb_transport_header(skb) - skb->head;
1277                         skb->csum_offset = offsetof(struct udphdr, check);
1278                         uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1279                                                        inet->inet_daddr,
1280                                                        udp_len, IPPROTO_UDP, 0);
1281                 }
1282                 break;
1283
1284         case L2TP_ENCAPTYPE_IP:
1285                 break;
1286         }
1287
1288         l2tp_skb_set_owner_w(skb, sk);
1289
1290         l2tp_xmit_core(session, skb, fl, data_len);
1291 out_unlock:
1292         bh_unlock_sock(sk);
1293
1294         return ret;
1295 }
1296 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1297
1298 /*****************************************************************************
1299  * Tinnel and session create/destroy.
1300  *****************************************************************************/
1301
1302 /* Tunnel socket destruct hook.
1303  * The tunnel context is deleted only when all session sockets have been
1304  * closed.
1305  */
1306 static void l2tp_tunnel_destruct(struct sock *sk)
1307 {
1308         struct l2tp_tunnel *tunnel;
1309         struct l2tp_net *pn;
1310
1311         tunnel = sk->sk_user_data;
1312         if (tunnel == NULL)
1313                 goto end;
1314
1315         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1316
1317
1318         /* Disable udp encapsulation */
1319         switch (tunnel->encap) {
1320         case L2TP_ENCAPTYPE_UDP:
1321                 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1322                 (udp_sk(sk))->encap_type = 0;
1323                 (udp_sk(sk))->encap_rcv = NULL;
1324                 (udp_sk(sk))->encap_destroy = NULL;
1325                 break;
1326         case L2TP_ENCAPTYPE_IP:
1327                 break;
1328         }
1329
1330         /* Remove hooks into tunnel socket */
1331         sk->sk_destruct = tunnel->old_sk_destruct;
1332         sk->sk_user_data = NULL;
1333         tunnel->sock = NULL;
1334
1335         /* Remove the tunnel struct from the tunnel list */
1336         pn = l2tp_pernet(tunnel->l2tp_net);
1337         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1338         list_del_rcu(&tunnel->list);
1339         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1340         atomic_dec(&l2tp_tunnel_count);
1341
1342         l2tp_tunnel_closeall(tunnel);
1343         l2tp_tunnel_dec_refcount(tunnel);
1344
1345         /* Call the original destructor */
1346         if (sk->sk_destruct)
1347                 (*sk->sk_destruct)(sk);
1348 end:
1349         return;
1350 }
1351
1352 /* When the tunnel is closed, all the attached sessions need to go too.
1353  */
1354 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1355 {
1356         int hash;
1357         struct hlist_node *walk;
1358         struct hlist_node *tmp;
1359         struct l2tp_session *session;
1360
1361         BUG_ON(tunnel == NULL);
1362
1363         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1364                   tunnel->name);
1365
1366         write_lock_bh(&tunnel->hlist_lock);
1367         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1368 again:
1369                 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1370                         session = hlist_entry(walk, struct l2tp_session, hlist);
1371
1372                         l2tp_info(session, L2TP_MSG_CONTROL,
1373                                   "%s: closing session\n", session->name);
1374
1375                         hlist_del_init(&session->hlist);
1376
1377                         if (session->ref != NULL)
1378                                 (*session->ref)(session);
1379
1380                         write_unlock_bh(&tunnel->hlist_lock);
1381
1382                         __l2tp_session_unhash(session);
1383                         l2tp_session_queue_purge(session);
1384
1385                         if (session->session_close != NULL)
1386                                 (*session->session_close)(session);
1387
1388                         if (session->deref != NULL)
1389                                 (*session->deref)(session);
1390
1391                         l2tp_session_dec_refcount(session);
1392
1393                         write_lock_bh(&tunnel->hlist_lock);
1394
1395                         /* Now restart from the beginning of this hash
1396                          * chain.  We always remove a session from the
1397                          * list so we are guaranteed to make forward
1398                          * progress.
1399                          */
1400                         goto again;
1401                 }
1402         }
1403         write_unlock_bh(&tunnel->hlist_lock);
1404 }
1405 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
1406
1407 /* Tunnel socket destroy hook for UDP encapsulation */
1408 static void l2tp_udp_encap_destroy(struct sock *sk)
1409 {
1410         struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
1411         if (tunnel) {
1412                 l2tp_tunnel_closeall(tunnel);
1413                 sock_put(sk);
1414         }
1415 }
1416
1417 /* Really kill the tunnel.
1418  * Come here only when all sessions have been cleared from the tunnel.
1419  */
1420 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1421 {
1422         BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1423         BUG_ON(tunnel->sock != NULL);
1424         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name);
1425         kfree_rcu(tunnel, rcu);
1426 }
1427
1428 /* Workqueue tunnel deletion function */
1429 static void l2tp_tunnel_del_work(struct work_struct *work)
1430 {
1431         struct l2tp_tunnel *tunnel = NULL;
1432         struct socket *sock = NULL;
1433         struct sock *sk = NULL;
1434
1435         tunnel = container_of(work, struct l2tp_tunnel, del_work);
1436         sk = l2tp_tunnel_sock_lookup(tunnel);
1437         if (!sk)
1438                 return;
1439
1440         sock = sk->sk_socket;
1441
1442         /* If the tunnel socket was created by userspace, then go through the
1443          * inet layer to shut the socket down, and let userspace close it.
1444          * Otherwise, if we created the socket directly within the kernel, use
1445          * the sk API to release it here.
1446          * In either case the tunnel resources are freed in the socket
1447          * destructor when the tunnel socket goes away.
1448          */
1449         if (tunnel->fd >= 0) {
1450                 if (sock)
1451                         inet_shutdown(sock, 2);
1452         } else {
1453                 if (sock)
1454                         kernel_sock_shutdown(sock, SHUT_RDWR);
1455                 sk_release_kernel(sk);
1456         }
1457
1458         l2tp_tunnel_sock_put(sk);
1459 }
1460
1461 /* Create a socket for the tunnel, if one isn't set up by
1462  * userspace. This is used for static tunnels where there is no
1463  * managing L2TP daemon.
1464  *
1465  * Since we don't want these sockets to keep a namespace alive by
1466  * themselves, we drop the socket's namespace refcount after creation.
1467  * These sockets are freed when the namespace exits using the pernet
1468  * exit hook.
1469  */
1470 static int l2tp_tunnel_sock_create(struct net *net,
1471                                 u32 tunnel_id,
1472                                 u32 peer_tunnel_id,
1473                                 struct l2tp_tunnel_cfg *cfg,
1474                                 struct socket **sockp)
1475 {
1476         int err = -EINVAL;
1477         struct socket *sock = NULL;
1478         struct sockaddr_in udp_addr = {0};
1479         struct sockaddr_l2tpip ip_addr = {0};
1480 #if IS_ENABLED(CONFIG_IPV6)
1481         struct sockaddr_in6 udp6_addr = {0};
1482         struct sockaddr_l2tpip6 ip6_addr = {0};
1483 #endif
1484
1485         switch (cfg->encap) {
1486         case L2TP_ENCAPTYPE_UDP:
1487 #if IS_ENABLED(CONFIG_IPV6)
1488                 if (cfg->local_ip6 && cfg->peer_ip6) {
1489                         err = sock_create_kern(AF_INET6, SOCK_DGRAM, 0, &sock);
1490                         if (err < 0)
1491                                 goto out;
1492
1493                         sk_change_net(sock->sk, net);
1494
1495                         udp6_addr.sin6_family = AF_INET6;
1496                         memcpy(&udp6_addr.sin6_addr, cfg->local_ip6,
1497                                sizeof(udp6_addr.sin6_addr));
1498                         udp6_addr.sin6_port = htons(cfg->local_udp_port);
1499                         err = kernel_bind(sock, (struct sockaddr *) &udp6_addr,
1500                                           sizeof(udp6_addr));
1501                         if (err < 0)
1502                                 goto out;
1503
1504                         udp6_addr.sin6_family = AF_INET6;
1505                         memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6,
1506                                sizeof(udp6_addr.sin6_addr));
1507                         udp6_addr.sin6_port = htons(cfg->peer_udp_port);
1508                         err = kernel_connect(sock,
1509                                              (struct sockaddr *) &udp6_addr,
1510                                              sizeof(udp6_addr), 0);
1511                         if (err < 0)
1512                                 goto out;
1513                 } else
1514 #endif
1515                 {
1516                         err = sock_create_kern(AF_INET, SOCK_DGRAM, 0, &sock);
1517                         if (err < 0)
1518                                 goto out;
1519
1520                         sk_change_net(sock->sk, net);
1521
1522                         udp_addr.sin_family = AF_INET;
1523                         udp_addr.sin_addr = cfg->local_ip;
1524                         udp_addr.sin_port = htons(cfg->local_udp_port);
1525                         err = kernel_bind(sock, (struct sockaddr *) &udp_addr,
1526                                           sizeof(udp_addr));
1527                         if (err < 0)
1528                                 goto out;
1529
1530                         udp_addr.sin_family = AF_INET;
1531                         udp_addr.sin_addr = cfg->peer_ip;
1532                         udp_addr.sin_port = htons(cfg->peer_udp_port);
1533                         err = kernel_connect(sock,
1534                                              (struct sockaddr *) &udp_addr,
1535                                              sizeof(udp_addr), 0);
1536                         if (err < 0)
1537                                 goto out;
1538                 }
1539
1540                 if (!cfg->use_udp_checksums)
1541                         sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1542
1543                 break;
1544
1545         case L2TP_ENCAPTYPE_IP:
1546 #if IS_ENABLED(CONFIG_IPV6)
1547                 if (cfg->local_ip6 && cfg->peer_ip6) {
1548                         err = sock_create_kern(AF_INET6, SOCK_DGRAM,
1549                                           IPPROTO_L2TP, &sock);
1550                         if (err < 0)
1551                                 goto out;
1552
1553                         sk_change_net(sock->sk, net);
1554
1555                         ip6_addr.l2tp_family = AF_INET6;
1556                         memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1557                                sizeof(ip6_addr.l2tp_addr));
1558                         ip6_addr.l2tp_conn_id = tunnel_id;
1559                         err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1560                                           sizeof(ip6_addr));
1561                         if (err < 0)
1562                                 goto out;
1563
1564                         ip6_addr.l2tp_family = AF_INET6;
1565                         memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1566                                sizeof(ip6_addr.l2tp_addr));
1567                         ip6_addr.l2tp_conn_id = peer_tunnel_id;
1568                         err = kernel_connect(sock,
1569                                              (struct sockaddr *) &ip6_addr,
1570                                              sizeof(ip6_addr), 0);
1571                         if (err < 0)
1572                                 goto out;
1573                 } else
1574 #endif
1575                 {
1576                         err = sock_create_kern(AF_INET, SOCK_DGRAM,
1577                                           IPPROTO_L2TP, &sock);
1578                         if (err < 0)
1579                                 goto out;
1580
1581                         sk_change_net(sock->sk, net);
1582
1583                         ip_addr.l2tp_family = AF_INET;
1584                         ip_addr.l2tp_addr = cfg->local_ip;
1585                         ip_addr.l2tp_conn_id = tunnel_id;
1586                         err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1587                                           sizeof(ip_addr));
1588                         if (err < 0)
1589                                 goto out;
1590
1591                         ip_addr.l2tp_family = AF_INET;
1592                         ip_addr.l2tp_addr = cfg->peer_ip;
1593                         ip_addr.l2tp_conn_id = peer_tunnel_id;
1594                         err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1595                                              sizeof(ip_addr), 0);
1596                         if (err < 0)
1597                                 goto out;
1598                 }
1599                 break;
1600
1601         default:
1602                 goto out;
1603         }
1604
1605 out:
1606         *sockp = sock;
1607         if ((err < 0) && sock) {
1608                 kernel_sock_shutdown(sock, SHUT_RDWR);
1609                 sk_release_kernel(sock->sk);
1610                 *sockp = NULL;
1611         }
1612
1613         return err;
1614 }
1615
1616 static struct lock_class_key l2tp_socket_class;
1617
1618 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)
1619 {
1620         struct l2tp_tunnel *tunnel = NULL;
1621         int err;
1622         struct socket *sock = NULL;
1623         struct sock *sk = NULL;
1624         struct l2tp_net *pn;
1625         enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1626
1627         /* Get the tunnel socket from the fd, which was opened by
1628          * the userspace L2TP daemon. If not specified, create a
1629          * kernel socket.
1630          */
1631         if (fd < 0) {
1632                 err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id,
1633                                 cfg, &sock);
1634                 if (err < 0)
1635                         goto err;
1636         } else {
1637                 sock = sockfd_lookup(fd, &err);
1638                 if (!sock) {
1639                         pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n",
1640                                tunnel_id, fd, err);
1641                         err = -EBADF;
1642                         goto err;
1643                 }
1644
1645                 /* Reject namespace mismatches */
1646                 if (!net_eq(sock_net(sock->sk), net)) {
1647                         pr_err("tunl %u: netns mismatch\n", tunnel_id);
1648                         err = -EINVAL;
1649                         goto err;
1650                 }
1651         }
1652
1653         sk = sock->sk;
1654
1655         if (cfg != NULL)
1656                 encap = cfg->encap;
1657
1658         /* Quick sanity checks */
1659         switch (encap) {
1660         case L2TP_ENCAPTYPE_UDP:
1661                 err = -EPROTONOSUPPORT;
1662                 if (sk->sk_protocol != IPPROTO_UDP) {
1663                         pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1664                                tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1665                         goto err;
1666                 }
1667                 break;
1668         case L2TP_ENCAPTYPE_IP:
1669                 err = -EPROTONOSUPPORT;
1670                 if (sk->sk_protocol != IPPROTO_L2TP) {
1671                         pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1672                                tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1673                         goto err;
1674                 }
1675                 break;
1676         }
1677
1678         /* Check if this socket has already been prepped */
1679         tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
1680         if (tunnel != NULL) {
1681                 /* This socket has already been prepped */
1682                 err = -EBUSY;
1683                 goto err;
1684         }
1685
1686         tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1687         if (tunnel == NULL) {
1688                 err = -ENOMEM;
1689                 goto err;
1690         }
1691
1692         tunnel->version = version;
1693         tunnel->tunnel_id = tunnel_id;
1694         tunnel->peer_tunnel_id = peer_tunnel_id;
1695         tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1696
1697         tunnel->magic = L2TP_TUNNEL_MAGIC;
1698         sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1699         rwlock_init(&tunnel->hlist_lock);
1700
1701         /* The net we belong to */
1702         tunnel->l2tp_net = net;
1703         pn = l2tp_pernet(net);
1704
1705         if (cfg != NULL)
1706                 tunnel->debug = cfg->debug;
1707
1708 #if IS_ENABLED(CONFIG_IPV6)
1709         if (sk->sk_family == PF_INET6) {
1710                 struct ipv6_pinfo *np = inet6_sk(sk);
1711
1712                 if (ipv6_addr_v4mapped(&np->saddr) &&
1713                     ipv6_addr_v4mapped(&np->daddr)) {
1714                         struct inet_sock *inet = inet_sk(sk);
1715
1716                         tunnel->v4mapped = true;
1717                         inet->inet_saddr = np->saddr.s6_addr32[3];
1718                         inet->inet_rcv_saddr = np->rcv_saddr.s6_addr32[3];
1719                         inet->inet_daddr = np->daddr.s6_addr32[3];
1720                 } else {
1721                         tunnel->v4mapped = false;
1722                 }
1723         }
1724 #endif
1725
1726         /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1727         tunnel->encap = encap;
1728         if (encap == L2TP_ENCAPTYPE_UDP) {
1729                 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1730                 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1731                 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1732                 udp_sk(sk)->encap_destroy = l2tp_udp_encap_destroy;
1733 #if IS_ENABLED(CONFIG_IPV6)
1734                 if (sk->sk_family == PF_INET6 && !tunnel->v4mapped)
1735                         udpv6_encap_enable();
1736                 else
1737 #endif
1738                 udp_encap_enable();
1739         }
1740
1741         sk->sk_user_data = tunnel;
1742
1743         /* Hook on the tunnel socket destructor so that we can cleanup
1744          * if the tunnel socket goes away.
1745          */
1746         tunnel->old_sk_destruct = sk->sk_destruct;
1747         sk->sk_destruct = &l2tp_tunnel_destruct;
1748         tunnel->sock = sk;
1749         tunnel->fd = fd;
1750         lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
1751
1752         sk->sk_allocation = GFP_ATOMIC;
1753
1754         /* Init delete workqueue struct */
1755         INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
1756
1757         /* Add tunnel to our list */
1758         INIT_LIST_HEAD(&tunnel->list);
1759         atomic_inc(&l2tp_tunnel_count);
1760
1761         /* Bump the reference count. The tunnel context is deleted
1762          * only when this drops to zero. Must be done before list insertion
1763          */
1764         l2tp_tunnel_inc_refcount(tunnel);
1765         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1766         list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1767         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1768
1769         err = 0;
1770 err:
1771         if (tunnelp)
1772                 *tunnelp = tunnel;
1773
1774         /* If tunnel's socket was created by the kernel, it doesn't
1775          *  have a file.
1776          */
1777         if (sock && sock->file)
1778                 sockfd_put(sock);
1779
1780         return err;
1781 }
1782 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1783
1784 /* This function is used by the netlink TUNNEL_DELETE command.
1785  */
1786 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1787 {
1788         l2tp_tunnel_closeall(tunnel);
1789         return (false == queue_work(l2tp_wq, &tunnel->del_work));
1790 }
1791 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1792
1793 /* Really kill the session.
1794  */
1795 void l2tp_session_free(struct l2tp_session *session)
1796 {
1797         struct l2tp_tunnel *tunnel = session->tunnel;
1798
1799         BUG_ON(atomic_read(&session->ref_count) != 0);
1800
1801         if (tunnel) {
1802                 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1803                 if (session->session_id != 0)
1804                         atomic_dec(&l2tp_session_count);
1805                 sock_put(tunnel->sock);
1806                 session->tunnel = NULL;
1807                 l2tp_tunnel_dec_refcount(tunnel);
1808         }
1809
1810         kfree(session);
1811
1812         return;
1813 }
1814 EXPORT_SYMBOL_GPL(l2tp_session_free);
1815
1816 /* Remove an l2tp session from l2tp_core's hash lists.
1817  * Provides a tidyup interface for pseudowire code which can't just route all
1818  * shutdown via. l2tp_session_delete and a pseudowire-specific session_close
1819  * callback.
1820  */
1821 void __l2tp_session_unhash(struct l2tp_session *session)
1822 {
1823         struct l2tp_tunnel *tunnel = session->tunnel;
1824
1825         /* Remove the session from core hashes */
1826         if (tunnel) {
1827                 /* Remove from the per-tunnel hash */
1828                 write_lock_bh(&tunnel->hlist_lock);
1829                 hlist_del_init(&session->hlist);
1830                 write_unlock_bh(&tunnel->hlist_lock);
1831
1832                 /* For L2TPv3 we have a per-net hash: remove from there, too */
1833                 if (tunnel->version != L2TP_HDR_VER_2) {
1834                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1835                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1836                         hlist_del_init_rcu(&session->global_hlist);
1837                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1838                         synchronize_rcu();
1839                 }
1840         }
1841 }
1842 EXPORT_SYMBOL_GPL(__l2tp_session_unhash);
1843
1844 /* This function is used by the netlink SESSION_DELETE command and by
1845    pseudowire modules.
1846  */
1847 int l2tp_session_delete(struct l2tp_session *session)
1848 {
1849         if (session->ref)
1850                 (*session->ref)(session);
1851         __l2tp_session_unhash(session);
1852         l2tp_session_queue_purge(session);
1853         if (session->session_close != NULL)
1854                 (*session->session_close)(session);
1855         if (session->deref)
1856                 (*session->deref)(session);
1857         l2tp_session_dec_refcount(session);
1858         return 0;
1859 }
1860 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1861
1862 /* We come here whenever a session's send_seq, cookie_len or
1863  * l2specific_len parameters are set.
1864  */
1865 static void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1866 {
1867         if (version == L2TP_HDR_VER_2) {
1868                 session->hdr_len = 6;
1869                 if (session->send_seq)
1870                         session->hdr_len += 4;
1871         } else {
1872                 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1873                 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1874                         session->hdr_len += 4;
1875         }
1876
1877 }
1878
1879 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)
1880 {
1881         struct l2tp_session *session;
1882
1883         session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1884         if (session != NULL) {
1885                 session->magic = L2TP_SESSION_MAGIC;
1886                 session->tunnel = tunnel;
1887
1888                 session->session_id = session_id;
1889                 session->peer_session_id = peer_session_id;
1890                 session->nr = 0;
1891                 if (tunnel->version == L2TP_HDR_VER_2)
1892                         session->nr_max = 0xffff;
1893                 else
1894                         session->nr_max = 0xffffff;
1895                 session->nr_window_size = session->nr_max / 2;
1896                 session->nr_oos_count_max = 4;
1897
1898                 /* Use NR of first received packet */
1899                 session->reorder_skip = 1;
1900
1901                 sprintf(&session->name[0], "sess %u/%u",
1902                         tunnel->tunnel_id, session->session_id);
1903
1904                 skb_queue_head_init(&session->reorder_q);
1905
1906                 INIT_HLIST_NODE(&session->hlist);
1907                 INIT_HLIST_NODE(&session->global_hlist);
1908
1909                 /* Inherit debug options from tunnel */
1910                 session->debug = tunnel->debug;
1911
1912                 if (cfg) {
1913                         session->pwtype = cfg->pw_type;
1914                         session->debug = cfg->debug;
1915                         session->mtu = cfg->mtu;
1916                         session->mru = cfg->mru;
1917                         session->send_seq = cfg->send_seq;
1918                         session->recv_seq = cfg->recv_seq;
1919                         session->lns_mode = cfg->lns_mode;
1920                         session->reorder_timeout = cfg->reorder_timeout;
1921                         session->offset = cfg->offset;
1922                         session->l2specific_type = cfg->l2specific_type;
1923                         session->l2specific_len = cfg->l2specific_len;
1924                         session->cookie_len = cfg->cookie_len;
1925                         memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1926                         session->peer_cookie_len = cfg->peer_cookie_len;
1927                         memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1928                 }
1929
1930                 if (tunnel->version == L2TP_HDR_VER_2)
1931                         session->build_header = l2tp_build_l2tpv2_header;
1932                 else
1933                         session->build_header = l2tp_build_l2tpv3_header;
1934
1935                 l2tp_session_set_header_len(session, tunnel->version);
1936
1937                 /* Bump the reference count. The session context is deleted
1938                  * only when this drops to zero.
1939                  */
1940                 l2tp_session_inc_refcount(session);
1941                 l2tp_tunnel_inc_refcount(tunnel);
1942
1943                 /* Ensure tunnel socket isn't deleted */
1944                 sock_hold(tunnel->sock);
1945
1946                 /* Add session to the tunnel's hash list */
1947                 write_lock_bh(&tunnel->hlist_lock);
1948                 hlist_add_head(&session->hlist,
1949                                l2tp_session_id_hash(tunnel, session_id));
1950                 write_unlock_bh(&tunnel->hlist_lock);
1951
1952                 /* And to the global session list if L2TPv3 */
1953                 if (tunnel->version != L2TP_HDR_VER_2) {
1954                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1955
1956                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1957                         hlist_add_head_rcu(&session->global_hlist,
1958                                            l2tp_session_id_hash_2(pn, session_id));
1959                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1960                 }
1961
1962                 /* Ignore management session in session count value */
1963                 if (session->session_id != 0)
1964                         atomic_inc(&l2tp_session_count);
1965         }
1966
1967         return session;
1968 }
1969 EXPORT_SYMBOL_GPL(l2tp_session_create);
1970
1971 /*****************************************************************************
1972  * Init and cleanup
1973  *****************************************************************************/
1974
1975 static __net_init int l2tp_init_net(struct net *net)
1976 {
1977         struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1978         int hash;
1979
1980         INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1981         spin_lock_init(&pn->l2tp_tunnel_list_lock);
1982
1983         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1984                 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1985
1986         spin_lock_init(&pn->l2tp_session_hlist_lock);
1987
1988         return 0;
1989 }
1990
1991 static __net_exit void l2tp_exit_net(struct net *net)
1992 {
1993         struct l2tp_net *pn = l2tp_pernet(net);
1994         struct l2tp_tunnel *tunnel = NULL;
1995
1996         rcu_read_lock_bh();
1997         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
1998                 (void)l2tp_tunnel_delete(tunnel);
1999         }
2000         rcu_read_unlock_bh();
2001 }
2002
2003 static struct pernet_operations l2tp_net_ops = {
2004         .init = l2tp_init_net,
2005         .exit = l2tp_exit_net,
2006         .id   = &l2tp_net_id,
2007         .size = sizeof(struct l2tp_net),
2008 };
2009
2010 static int __init l2tp_init(void)
2011 {
2012         int rc = 0;
2013
2014         rc = register_pernet_device(&l2tp_net_ops);
2015         if (rc)
2016                 goto out;
2017
2018         l2tp_wq = alloc_workqueue("l2tp", WQ_NON_REENTRANT | WQ_UNBOUND, 0);
2019         if (!l2tp_wq) {
2020                 pr_err("alloc_workqueue failed\n");
2021                 rc = -ENOMEM;
2022                 goto out;
2023         }
2024
2025         pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
2026
2027 out:
2028         return rc;
2029 }
2030
2031 static void __exit l2tp_exit(void)
2032 {
2033         unregister_pernet_device(&l2tp_net_ops);
2034         if (l2tp_wq) {
2035                 destroy_workqueue(l2tp_wq);
2036                 l2tp_wq = NULL;
2037         }
2038 }
2039
2040 module_init(l2tp_init);
2041 module_exit(l2tp_exit);
2042
2043 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
2044 MODULE_DESCRIPTION("L2TP core");
2045 MODULE_LICENSE("GPL");
2046 MODULE_VERSION(L2TP_DRV_VERSION);
2047