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 #include <linux/module.h>
  22 #include <linux/string.h>
  23 #include <linux/list.h>
  24 #include <linux/rculist.h>
  25 #include <linux/uaccess.h>
  26
  27 #include <linux/kernel.h>
  28 #include <linux/spinlock.h>
  29 #include <linux/kthread.h>
  30 #include <linux/sched.h>
  31 #include <linux/slab.h>
  32 #include <linux/errno.h>
  33 #include <linux/jiffies.h>
  34
  35 #include <linux/netdevice.h>
  36 #include <linux/net.h>
  37 #include <linux/inetdevice.h>
  38 #include <linux/skbuff.h>
  39 #include <linux/init.h>
  40 #include <linux/in.h>
  41 #include <linux/ip.h>
  42 #include <linux/udp.h>
  43 #include <linux/l2tp.h>
  44 #include <linux/hash.h>
  45 #include <linux/sort.h>
  46 #include <linux/file.h>
  47 #include <linux/nsproxy.h>
  48 #include <net/net_namespace.h>
  49 #include <net/netns/generic.h>
  50 #include <net/dst.h>
  51 #include <net/ip.h>
  52 #include <net/udp.h>
  53 #include <net/inet_common.h>
  54 #include <net/xfrm.h>
  55 #include <net/protocol.h>
  56
  57 #include <asm/byteorder.h>
  58 #include <asm/atomic.h>
  59
  60 #include "l2tp_core.h"
  61
  62 #define L2TP_DRV_VERSION        "V2.0"
  63
  64 /* L2TP header constants */
  65 #define L2TP_HDRFLAG_T     0x8000
  66 #define L2TP_HDRFLAG_L     0x4000
  67 #define L2TP_HDRFLAG_S     0x0800
  68 #define L2TP_HDRFLAG_O     0x0200
  69 #define L2TP_HDRFLAG_P     0x0100
  70
  71 #define L2TP_HDR_VER_MASK  0x000F
  72 #define L2TP_HDR_VER_2     0x0002
  73 #define L2TP_HDR_VER_3     0x0003
  74
  75 /* L2TPv3 default L2-specific sublayer */
  76 #define L2TP_SLFLAG_S      0x40000000
  77 #define L2TP_SL_SEQ_MASK   0x00ffffff
  78
  79 #define L2TP_HDR_SIZE_SEQ               10
  80 #define L2TP_HDR_SIZE_NOSEQ             6
  81
  82 /* Default trace flags */
  83 #define L2TP_DEFAULT_DEBUG_FLAGS        0
  84
  85 #define PRINTK(_mask, _type, _lvl, _fmt, args...)                       \
  86         do {                                                            \
  87                 if ((_mask) & (_type))                                  \
  88                         printk(_lvl "L2TP: " _fmt, ##args);             \
  89         } while (0)
  90
  91 /* Private data stored for received packets in the skb.
  92  */
  93 struct l2tp_skb_cb {
  94         u32                     ns;
  95         u16                     has_seq;
  96         u16                     length;
  97         unsigned long           expires;
  98 };
  99
 100 #define L2TP_SKB_CB(skb)        ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
 101
 102 static atomic_t l2tp_tunnel_count;
 103 static atomic_t l2tp_session_count;
 104
 105 /* per-net private data for this module */
 106 static unsigned int l2tp_net_id;
 107 struct l2tp_net {
 108         struct list_head l2tp_tunnel_list;
 109         spinlock_t l2tp_tunnel_list_lock;
 110         struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
 111         spinlock_t l2tp_session_hlist_lock;
 112 };
 113
 114 static inline struct l2tp_net *l2tp_pernet(struct net *net)
 115 {
 116         BUG_ON(!net);
 117
 118         return net_generic(net, l2tp_net_id);
 119 }
 120
 121 /* Session hash global list for L2TPv3.
 122  * The session_id SHOULD be random according to RFC3931, but several
 123  * L2TP implementations use incrementing session_ids.  So we do a real
 124  * hash on the session_id, rather than a simple bitmask.
 125  */
 126 static inline struct hlist_head *
 127 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
 128 {
 129         return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
 130
 131 }
 132
 133 /* Lookup a session by id in the global session list
 134  */
 135 static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id)
 136 {
 137         struct l2tp_net *pn = l2tp_pernet(net);
 138         struct hlist_head *session_list =
 139                 l2tp_session_id_hash_2(pn, session_id);
 140         struct l2tp_session *session;
 141         struct hlist_node *walk;
 142
 143         rcu_read_lock_bh();
 144         hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) {
 145                 if (session->session_id == session_id) {
 146                         rcu_read_unlock_bh();
 147                         return session;
 148                 }
 149         }
 150         rcu_read_unlock_bh();
 151
 152         return NULL;
 153 }
 154
 155 /* Session hash list.
 156  * The session_id SHOULD be random according to RFC2661, but several
 157  * L2TP implementations (Cisco and Microsoft) use incrementing
 158  * session_ids.  So we do a real hash on the session_id, rather than a
 159  * simple bitmask.
 160  */
 161 static inline struct hlist_head *
 162 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
 163 {
 164         return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
 165 }
 166
 167 /* Lookup a session by id
 168  */
 169 struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id)
 170 {
 171         struct hlist_head *session_list;
 172         struct l2tp_session *session;
 173         struct hlist_node *walk;
 174
 175         /* In L2TPv3, session_ids are unique over all tunnels and we
 176          * sometimes need to look them up before we know the
 177          * tunnel.
 178          */
 179         if (tunnel == NULL)
 180                 return l2tp_session_find_2(net, session_id);
 181
 182         session_list = l2tp_session_id_hash(tunnel, session_id);
 183         read_lock_bh(&tunnel->hlist_lock);
 184         hlist_for_each_entry(session, walk, session_list, hlist) {
 185                 if (session->session_id == session_id) {
 186                         read_unlock_bh(&tunnel->hlist_lock);
 187                         return session;
 188                 }
 189         }
 190         read_unlock_bh(&tunnel->hlist_lock);
 191
 192         return NULL;
 193 }
 194 EXPORT_SYMBOL_GPL(l2tp_session_find);
 195
 196 struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
 197 {
 198         int hash;
 199         struct hlist_node *walk;
 200         struct l2tp_session *session;
 201         int count = 0;
 202
 203         read_lock_bh(&tunnel->hlist_lock);
 204         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
 205                 hlist_for_each_entry(session, walk, &tunnel->session_hlist[hash], hlist) {
 206                         if (++count > nth) {
 207                                 read_unlock_bh(&tunnel->hlist_lock);
 208                                 return session;
 209                         }
 210                 }
 211         }
 212
 213         read_unlock_bh(&tunnel->hlist_lock);
 214
 215         return NULL;
 216 }
 217 EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
 218
 219 /* Lookup a session by interface name.
 220  * This is very inefficient but is only used by management interfaces.
 221  */
 222 struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname)
 223 {
 224         struct l2tp_net *pn = l2tp_pernet(net);
 225         int hash;
 226         struct hlist_node *walk;
 227         struct l2tp_session *session;
 228
 229         rcu_read_lock_bh();
 230         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
 231                 hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) {
 232                         if (!strcmp(session->ifname, ifname)) {
 233                                 rcu_read_unlock_bh();
 234                                 return session;
 235                         }
 236                 }
 237         }
 238
 239         rcu_read_unlock_bh();
 240
 241         return NULL;
 242 }
 243 EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);
 244
 245 /* Lookup a tunnel by id
 246  */
 247 struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
 248 {
 249         struct l2tp_tunnel *tunnel;
 250         struct l2tp_net *pn = l2tp_pernet(net);
 251
 252         rcu_read_lock_bh();
 253         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 254                 if (tunnel->tunnel_id == tunnel_id) {
 255                         rcu_read_unlock_bh();
 256                         return tunnel;
 257                 }
 258         }
 259         rcu_read_unlock_bh();
 260
 261         return NULL;
 262 }
 263 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
 264
 265 struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
 266 {
 267         struct l2tp_net *pn = l2tp_pernet(net);
 268         struct l2tp_tunnel *tunnel;
 269         int count = 0;
 270
 271         rcu_read_lock_bh();
 272         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 273                 if (++count > nth) {
 274                         rcu_read_unlock_bh();
 275                         return tunnel;
 276                 }
 277         }
 278
 279         rcu_read_unlock_bh();
 280
 281         return NULL;
 282 }
 283 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
 284
 285 /*****************************************************************************
 286  * Receive data handling
 287  *****************************************************************************/
 288
 289 /* Queue a skb in order. We come here only if the skb has an L2TP sequence
 290  * number.
 291  */
 292 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
 293 {
 294         struct sk_buff *skbp;
 295         struct sk_buff *tmp;
 296         u32 ns = L2TP_SKB_CB(skb)->ns;
 297
 298         spin_lock_bh(&session->reorder_q.lock);
 299         skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
 300                 if (L2TP_SKB_CB(skbp)->ns > ns) {
 301                         __skb_queue_before(&session->reorder_q, skbp, skb);
 302                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
 303                                "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
 304                                session->name, ns, L2TP_SKB_CB(skbp)->ns,
 305                                skb_queue_len(&session->reorder_q));
 306                         session->stats.rx_oos_packets++;
 307                         goto out;
 308                 }
 309         }
 310
 311         __skb_queue_tail(&session->reorder_q, skb);
 312
 313 out:
 314         spin_unlock_bh(&session->reorder_q.lock);
 315 }
 316
 317 /* Dequeue a single skb.
 318  */
 319 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
 320 {
 321         struct l2tp_tunnel *tunnel = session->tunnel;
 322         int length = L2TP_SKB_CB(skb)->length;
 323
 324         /* We're about to requeue the skb, so return resources
 325          * to its current owner (a socket receive buffer).
 326          */
 327         skb_orphan(skb);
 328
 329         tunnel->stats.rx_packets++;
 330         tunnel->stats.rx_bytes += length;
 331         session->stats.rx_packets++;
 332         session->stats.rx_bytes += length;
 333
 334         if (L2TP_SKB_CB(skb)->has_seq) {
 335                 /* Bump our Nr */
 336                 session->nr++;
 337                 if (tunnel->version == L2TP_HDR_VER_2)
 338                         session->nr &= 0xffff;
 339                 else
 340                         session->nr &= 0xffffff;
 341
 342                 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
 343                        "%s: updated nr to %hu\n", session->name, session->nr);
 344         }
 345
 346         /* call private receive handler */
 347         if (session->recv_skb != NULL)
 348                 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
 349         else
 350                 kfree_skb(skb);
 351
 352         if (session->deref)
 353                 (*session->deref)(session);
 354 }
 355
 356 /* Dequeue skbs from the session's reorder_q, subject to packet order.
 357  * Skbs that have been in the queue for too long are simply discarded.
 358  */
 359 static void l2tp_recv_dequeue(struct l2tp_session *session)
 360 {
 361         struct sk_buff *skb;
 362         struct sk_buff *tmp;
 363
 364         /* If the pkt at the head of the queue has the nr that we
 365          * expect to send up next, dequeue it and any other
 366          * in-sequence packets behind it.
 367          */
 368         spin_lock_bh(&session->reorder_q.lock);
 369         skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
 370                 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
 371                         session->stats.rx_seq_discards++;
 372                         session->stats.rx_errors++;
 373                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
 374                                "%s: oos pkt %u len %d discarded (too old), "
 375                                "waiting for %u, reorder_q_len=%d\n",
 376                                session->name, L2TP_SKB_CB(skb)->ns,
 377                                L2TP_SKB_CB(skb)->length, session->nr,
 378                                skb_queue_len(&session->reorder_q));
 379                         __skb_unlink(skb, &session->reorder_q);
 380                         kfree_skb(skb);
 381                         if (session->deref)
 382                                 (*session->deref)(session);
 383                         continue;
 384                 }
 385
 386                 if (L2TP_SKB_CB(skb)->has_seq) {
 387                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
 388                                 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
 389                                        "%s: holding oos pkt %u len %d, "
 390                                        "waiting for %u, reorder_q_len=%d\n",
 391                                        session->name, L2TP_SKB_CB(skb)->ns,
 392                                        L2TP_SKB_CB(skb)->length, session->nr,
 393                                        skb_queue_len(&session->reorder_q));
 394                                 goto out;
 395                         }
 396                 }
 397                 __skb_unlink(skb, &session->reorder_q);
 398
 399                 /* Process the skb. We release the queue lock while we
 400                  * do so to let other contexts process the queue.
 401                  */
 402                 spin_unlock_bh(&session->reorder_q.lock);
 403                 l2tp_recv_dequeue_skb(session, skb);
 404                 spin_lock_bh(&session->reorder_q.lock);
 405         }
 406
 407 out:
 408         spin_unlock_bh(&session->reorder_q.lock);
 409 }
 410
 411 static inline int l2tp_verify_udp_checksum(struct sock *sk,
 412                                            struct sk_buff *skb)
 413 {
 414         struct udphdr *uh = udp_hdr(skb);
 415         u16 ulen = ntohs(uh->len);
 416         struct inet_sock *inet;
 417         __wsum psum;
 418
 419         if (sk->sk_no_check || skb_csum_unnecessary(skb) || !uh->check)
 420                 return 0;
 421
 422         inet = inet_sk(sk);
 423         psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, ulen,
 424                                   IPPROTO_UDP, 0);
 425
 426         if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
 427             !csum_fold(csum_add(psum, skb->csum)))
 428                 return 0;
 429
 430         skb->csum = psum;
 431
 432         return __skb_checksum_complete(skb);
 433 }
 434
 435 /* Do receive processing of L2TP data frames. We handle both L2TPv2
 436  * and L2TPv3 data frames here.
 437  *
 438  * L2TPv2 Data Message Header
 439  *
 440  *  0                   1                   2                   3
 441  *  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
 442  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 443  * |T|L|x|x|S|x|O|P|x|x|x|x|  Ver  |          Length (opt)         |
 444  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 445  * |           Tunnel ID           |           Session ID          |
 446  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 447  * |             Ns (opt)          |             Nr (opt)          |
 448  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 449  * |      Offset Size (opt)        |    Offset pad... (opt)
 450  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 451  *
 452  * Data frames are marked by T=0. All other fields are the same as
 453  * those in L2TP control frames.
 454  *
 455  * L2TPv3 Data Message Header
 456  *
 457  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 458  * |                      L2TP Session Header                      |
 459  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 460  * |                      L2-Specific Sublayer                     |
 461  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 462  * |                        Tunnel Payload                      ...
 463  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 464  *
 465  * L2TPv3 Session Header Over IP
 466  *
 467  *  0                   1                   2                   3
 468  *  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
 469  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 470  * |                           Session ID                          |
 471  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 472  * |               Cookie (optional, maximum 64 bits)...
 473  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 474  *                                                                 |
 475  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 476  *
 477  * L2TPv3 L2-Specific Sublayer Format
 478  *
 479  *  0                   1                   2                   3
 480  *  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
 481  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 482  * |x|S|x|x|x|x|x|x|              Sequence Number                  |
 483  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 484  *
 485  * Cookie value, sublayer format and offset (pad) are negotiated with
 486  * the peer when the session is set up. Unlike L2TPv2, we do not need
 487  * to parse the packet header to determine if optional fields are
 488  * present.
 489  *
 490  * Caller must already have parsed the frame and determined that it is
 491  * a data (not control) frame before coming here. Fields up to the
 492  * session-id have already been parsed and ptr points to the data
 493  * after the session-id.
 494  */
 495 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 496                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 497                       int length, int (*payload_hook)(struct sk_buff *skb))
 498 {
 499         struct l2tp_tunnel *tunnel = session->tunnel;
 500         int offset;
 501         u32 ns, nr;
 502
 503         /* The ref count is increased since we now hold a pointer to
 504          * the session. Take care to decrement the refcnt when exiting
 505          * this function from now on...
 506          */
 507         l2tp_session_inc_refcount(session);
 508         if (session->ref)
 509                 (*session->ref)(session);
 510
 511         /* Parse and check optional cookie */
 512         if (session->peer_cookie_len > 0) {
 513                 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
 514                         PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
 515                                "%s: cookie mismatch (%u/%u). Discarding.\n",
 516                                tunnel->name, tunnel->tunnel_id, session->session_id);
 517                         session->stats.rx_cookie_discards++;
 518                         goto discard;
 519                 }
 520                 ptr += session->peer_cookie_len;
 521         }
 522
 523         /* Handle the optional sequence numbers. Sequence numbers are
 524          * in different places for L2TPv2 and L2TPv3.
 525          *
 526          * If we are the LAC, enable/disable sequence numbers under
 527          * the control of the LNS.  If no sequence numbers present but
 528          * we were expecting them, discard frame.
 529          */
 530         ns = nr = 0;
 531         L2TP_SKB_CB(skb)->has_seq = 0;
 532         if (tunnel->version == L2TP_HDR_VER_2) {
 533                 if (hdrflags & L2TP_HDRFLAG_S) {
 534                         ns = ntohs(*(__be16 *) ptr);
 535                         ptr += 2;
 536                         nr = ntohs(*(__be16 *) ptr);
 537                         ptr += 2;
 538
 539                         /* Store L2TP info in the skb */
 540                         L2TP_SKB_CB(skb)->ns = ns;
 541                         L2TP_SKB_CB(skb)->has_seq = 1;
 542
 543                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
 544                                "%s: recv data ns=%u, nr=%u, session nr=%u\n",
 545                                session->name, ns, nr, session->nr);
 546                 }
 547         } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
 548                 u32 l2h = ntohl(*(__be32 *) ptr);
 549
 550                 if (l2h & 0x40000000) {
 551                         ns = l2h & 0x00ffffff;
 552
 553                         /* Store L2TP info in the skb */
 554                         L2TP_SKB_CB(skb)->ns = ns;
 555                         L2TP_SKB_CB(skb)->has_seq = 1;
 556
 557                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
 558                                "%s: recv data ns=%u, session nr=%u\n",
 559                                session->name, ns, session->nr);
 560                 }
 561         }
 562
 563         /* Advance past L2-specific header, if present */
 564         ptr += session->l2specific_len;
 565
 566         if (L2TP_SKB_CB(skb)->has_seq) {
 567                 /* Received a packet with sequence numbers. If we're the LNS,
 568                  * check if we sre sending sequence numbers and if not,
 569                  * configure it so.
 570                  */
 571                 if ((!session->lns_mode) && (!session->send_seq)) {
 572                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
 573                                "%s: requested to enable seq numbers by LNS\n",
 574                                session->name);
 575                         session->send_seq = -1;
 576                         l2tp_session_set_header_len(session, tunnel->version);
 577                 }
 578         } else {
 579                 /* No sequence numbers.
 580                  * If user has configured mandatory sequence numbers, discard.
 581                  */
 582                 if (session->recv_seq) {
 583                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
 584                                "%s: recv data has no seq numbers when required. "
 585                                "Discarding\n", session->name);
 586                         session->stats.rx_seq_discards++;
 587                         goto discard;
 588                 }
 589
 590                 /* If we're the LAC and we're sending sequence numbers, the
 591                  * LNS has requested that we no longer send sequence numbers.
 592                  * If we're the LNS and we're sending sequence numbers, the
 593                  * LAC is broken. Discard the frame.
 594                  */
 595                 if ((!session->lns_mode) && (session->send_seq)) {
 596                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO,
 597                                "%s: requested to disable seq numbers by LNS\n",
 598                                session->name);
 599                         session->send_seq = 0;
 600                         l2tp_session_set_header_len(session, tunnel->version);
 601                 } else if (session->send_seq) {
 602                         PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
 603                                "%s: recv data has no seq numbers when required. "
 604                                "Discarding\n", session->name);
 605                         session->stats.rx_seq_discards++;
 606                         goto discard;
 607                 }
 608         }
 609
 610         /* Session data offset is handled differently for L2TPv2 and
 611          * L2TPv3. For L2TPv2, there is an optional 16-bit value in
 612          * the header. For L2TPv3, the offset is negotiated using AVPs
 613          * in the session setup control protocol.
 614          */
 615         if (tunnel->version == L2TP_HDR_VER_2) {
 616                 /* If offset bit set, skip it. */
 617                 if (hdrflags & L2TP_HDRFLAG_O) {
 618                         offset = ntohs(*(__be16 *)ptr);
 619                         ptr += 2 + offset;
 620                 }
 621         } else
 622                 ptr += session->offset;
 623
 624         offset = ptr - optr;
 625         if (!pskb_may_pull(skb, offset))
 626                 goto discard;
 627
 628         __skb_pull(skb, offset);
 629
 630         /* If caller wants to process the payload before we queue the
 631          * packet, do so now.
 632          */
 633         if (payload_hook)
 634                 if ((*payload_hook)(skb))
 635                         goto discard;
 636
 637         /* Prepare skb for adding to the session's reorder_q.  Hold
 638          * packets for max reorder_timeout or 1 second if not
 639          * reordering.
 640          */
 641         L2TP_SKB_CB(skb)->length = length;
 642         L2TP_SKB_CB(skb)->expires = jiffies +
 643                 (session->reorder_timeout ? session->reorder_timeout : HZ);
 644
 645         /* Add packet to the session's receive queue. Reordering is done here, if
 646          * enabled. Saved L2TP protocol info is stored in skb->sb[].
 647          */
 648         if (L2TP_SKB_CB(skb)->has_seq) {
 649                 if (session->reorder_timeout != 0) {
 650                         /* Packet reordering enabled. Add skb to session's
 651                          * reorder queue, in order of ns.
 652                          */
 653                         l2tp_recv_queue_skb(session, skb);
 654                 } else {
 655                         /* Packet reordering disabled. Discard out-of-sequence
 656                          * packets
 657                          */
 658                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
 659                                 session->stats.rx_seq_discards++;
 660                                 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
 661                                        "%s: oos pkt %u len %d discarded, "
 662                                        "waiting for %u, reorder_q_len=%d\n",
 663                                        session->name, L2TP_SKB_CB(skb)->ns,
 664                                        L2TP_SKB_CB(skb)->length, session->nr,
 665                                        skb_queue_len(&session->reorder_q));
 666                                 goto discard;
 667                         }
 668                         skb_queue_tail(&session->reorder_q, skb);
 669                 }
 670         } else {
 671                 /* No sequence numbers. Add the skb to the tail of the
 672                  * reorder queue. This ensures that it will be
 673                  * delivered after all previous sequenced skbs.
 674                  */
 675                 skb_queue_tail(&session->reorder_q, skb);
 676         }
 677
 678         /* Try to dequeue as many skbs from reorder_q as we can. */
 679         l2tp_recv_dequeue(session);
 680
 681         l2tp_session_dec_refcount(session);
 682
 683         return;
 684
 685 discard:
 686         session->stats.rx_errors++;
 687         kfree_skb(skb);
 688
 689         if (session->deref)
 690                 (*session->deref)(session);
 691
 692         l2tp_session_dec_refcount(session);
 693 }
 694 EXPORT_SYMBOL(l2tp_recv_common);
 695
 696 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
 697  * here. The skb is not on a list when we get here.
 698  * Returns 0 if the packet was a data packet and was successfully passed on.
 699  * Returns 1 if the packet was not a good data packet and could not be
 700  * forwarded.  All such packets are passed up to userspace to deal with.
 701  */
 702 int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
 703                        int (*payload_hook)(struct sk_buff *skb))
 704 {
 705         struct l2tp_session *session = NULL;
 706         unsigned char *ptr, *optr;
 707         u16 hdrflags;
 708         u32 tunnel_id, session_id;
 709         int offset;
 710         u16 version;
 711         int length;
 712
 713         if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
 714                 goto discard_bad_csum;
 715
 716         /* UDP always verifies the packet length. */
 717         __skb_pull(skb, sizeof(struct udphdr));
 718
 719         /* Short packet? */
 720         if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) {
 721                 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
 722                        "%s: recv short packet (len=%d)\n", tunnel->name, skb->len);
 723                 goto error;
 724         }
 725
 726         /* Point to L2TP header */
 727         optr = ptr = skb->data;
 728
 729         /* Trace packet contents, if enabled */
 730         if (tunnel->debug & L2TP_MSG_DATA) {
 731                 length = min(32u, skb->len);
 732                 if (!pskb_may_pull(skb, length))
 733                         goto error;
 734
 735                 printk(KERN_DEBUG "%s: recv: ", tunnel->name);
 736
 737                 offset = 0;
 738                 do {
 739                         printk(" %02X", ptr[offset]);
 740                 } while (++offset < length);
 741
 742                 printk("\n");
 743         }
 744
 745         /* Get L2TP header flags */
 746         hdrflags = ntohs(*(__be16 *) ptr);
 747
 748         /* Check protocol version */
 749         version = hdrflags & L2TP_HDR_VER_MASK;
 750         if (version != tunnel->version) {
 751                 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
 752                        "%s: recv protocol version mismatch: got %d expected %d\n",
 753                        tunnel->name, version, tunnel->version);
 754                 goto error;
 755         }
 756
 757         /* Get length of L2TP packet */
 758         length = skb->len;
 759
 760         /* If type is control packet, it is handled by userspace. */
 761         if (hdrflags & L2TP_HDRFLAG_T) {
 762                 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
 763                        "%s: recv control packet, len=%d\n", tunnel->name, length);
 764                 goto error;
 765         }
 766
 767         /* Skip flags */
 768         ptr += 2;
 769
 770         if (tunnel->version == L2TP_HDR_VER_2) {
 771                 /* If length is present, skip it */
 772                 if (hdrflags & L2TP_HDRFLAG_L)
 773                         ptr += 2;
 774
 775                 /* Extract tunnel and session ID */
 776                 tunnel_id = ntohs(*(__be16 *) ptr);
 777                 ptr += 2;
 778                 session_id = ntohs(*(__be16 *) ptr);
 779                 ptr += 2;
 780         } else {
 781                 ptr += 2;       /* skip reserved bits */
 782                 tunnel_id = tunnel->tunnel_id;
 783                 session_id = ntohl(*(__be32 *) ptr);
 784                 ptr += 4;
 785         }
 786
 787         /* Find the session context */
 788         session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id);
 789         if (!session || !session->recv_skb) {
 790                 /* Not found? Pass to userspace to deal with */
 791                 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
 792                        "%s: no session found (%u/%u). Passing up.\n",
 793                        tunnel->name, tunnel_id, session_id);
 794                 goto error;
 795         }
 796
 797         l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook);
 798
 799         return 0;
 800
 801 discard_bad_csum:
 802         LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
 803         UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
 804         tunnel->stats.rx_errors++;
 805         kfree_skb(skb);
 806
 807         return 0;
 808
 809 error:
 810         /* Put UDP header back */
 811         __skb_push(skb, sizeof(struct udphdr));
 812
 813         return 1;
 814 }
 815 EXPORT_SYMBOL_GPL(l2tp_udp_recv_core);
 816
 817 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
 818  * Return codes:
 819  * 0 : success.
 820  * <0: error
 821  * >0: skb should be passed up to userspace as UDP.
 822  */
 823 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 824 {
 825         struct l2tp_tunnel *tunnel;
 826
 827         tunnel = l2tp_sock_to_tunnel(sk);
 828         if (tunnel == NULL)
 829                 goto pass_up;
 830
 831         PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
 832                "%s: received %d bytes\n", tunnel->name, skb->len);
 833
 834         if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
 835                 goto pass_up_put;
 836
 837         sock_put(sk);
 838         return 0;
 839
 840 pass_up_put:
 841         sock_put(sk);
 842 pass_up:
 843         return 1;
 844 }
 845 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
 846
 847 /************************************************************************
 848  * Transmit handling
 849  ***********************************************************************/
 850
 851 /* Build an L2TP header for the session into the buffer provided.
 852  */
 853 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
 854 {
 855         struct l2tp_tunnel *tunnel = session->tunnel;
 856         __be16 *bufp = buf;
 857         __be16 *optr = buf;
 858         u16 flags = L2TP_HDR_VER_2;
 859         u32 tunnel_id = tunnel->peer_tunnel_id;
 860         u32 session_id = session->peer_session_id;
 861
 862         if (session->send_seq)
 863                 flags |= L2TP_HDRFLAG_S;
 864
 865         /* Setup L2TP header. */
 866         *bufp++ = htons(flags);
 867         *bufp++ = htons(tunnel_id);
 868         *bufp++ = htons(session_id);
 869         if (session->send_seq) {
 870                 *bufp++ = htons(session->ns);
 871                 *bufp++ = 0;
 872                 session->ns++;
 873                 session->ns &= 0xffff;
 874                 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
 875                        "%s: updated ns to %u\n", session->name, session->ns);
 876         }
 877
 878         return bufp - optr;
 879 }
 880
 881 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
 882 {
 883         struct l2tp_tunnel *tunnel = session->tunnel;
 884         char *bufp = buf;
 885         char *optr = bufp;
 886
 887         /* Setup L2TP header. The header differs slightly for UDP and
 888          * IP encapsulations. For UDP, there is 4 bytes of flags.
 889          */
 890         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
 891                 u16 flags = L2TP_HDR_VER_3;
 892                 *((__be16 *) bufp) = htons(flags);
 893                 bufp += 2;
 894                 *((__be16 *) bufp) = 0;
 895                 bufp += 2;
 896         }
 897
 898         *((__be32 *) bufp) = htonl(session->peer_session_id);
 899         bufp += 4;
 900         if (session->cookie_len) {
 901                 memcpy(bufp, &session->cookie[0], session->cookie_len);
 902                 bufp += session->cookie_len;
 903         }
 904         if (session->l2specific_len) {
 905                 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
 906                         u32 l2h = 0;
 907                         if (session->send_seq) {
 908                                 l2h = 0x40000000 | session->ns;
 909                                 session->ns++;
 910                                 session->ns &= 0xffffff;
 911                                 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
 912                                        "%s: updated ns to %u\n", session->name, session->ns);
 913                         }
 914
 915                         *((__be32 *) bufp) = htonl(l2h);
 916                 }
 917                 bufp += session->l2specific_len;
 918         }
 919         if (session->offset)
 920                 bufp += session->offset;
 921
 922         return bufp - optr;
 923 }
 924
 925 int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, size_t data_len)
 926 {
 927         struct l2tp_tunnel *tunnel = session->tunnel;
 928         unsigned int len = skb->len;
 929         int error;
 930
 931         /* Debug */
 932         if (session->send_seq)
 933                 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
 934                        "%s: send %Zd bytes, ns=%u\n", session->name,
 935                        data_len, session->ns - 1);
 936         else
 937                 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
 938                        "%s: send %Zd bytes\n", session->name, data_len);
 939
 940         if (session->debug & L2TP_MSG_DATA) {
 941                 int i;
 942                 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
 943                 unsigned char *datap = skb->data + uhlen;
 944
 945                 printk(KERN_DEBUG "%s: xmit:", session->name);
 946                 for (i = 0; i < (len - uhlen); i++) {
 947                         printk(" %02X", *datap++);
 948                         if (i == 31) {
 949                                 printk(" ...");
 950                                 break;
 951                         }
 952                 }
 953                 printk("\n");
 954         }
 955
 956         /* Queue the packet to IP for output */
 957         skb->local_df = 1;
 958         error = ip_queue_xmit(skb);
 959
 960         /* Update stats */
 961         if (error >= 0) {
 962                 tunnel->stats.tx_packets++;
 963                 tunnel->stats.tx_bytes += len;
 964                 session->stats.tx_packets++;
 965                 session->stats.tx_bytes += len;
 966         } else {
 967                 tunnel->stats.tx_errors++;
 968                 session->stats.tx_errors++;
 969         }
 970
 971         return 0;
 972 }
 973 EXPORT_SYMBOL_GPL(l2tp_xmit_core);
 974
 975 /* Automatically called when the skb is freed.
 976  */
 977 static void l2tp_sock_wfree(struct sk_buff *skb)
 978 {
 979         sock_put(skb->sk);
 980 }
 981
 982 /* For data skbs that we transmit, we associate with the tunnel socket
 983  * but don't do accounting.
 984  */
 985 static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
 986 {
 987         sock_hold(sk);
 988         skb->sk = sk;
 989         skb->destructor = l2tp_sock_wfree;
 990 }
 991
 992 /* If caller requires the skb to have a ppp header, the header must be
 993  * inserted in the skb data before calling this function.
 994  */
 995 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
 996 {
 997         int data_len = skb->len;
 998         struct l2tp_tunnel *tunnel = session->tunnel;
 999         struct sock *sk = tunnel->sock;
1000         struct udphdr *uh;
1001         struct inet_sock *inet;
1002         __wsum csum;
1003         int old_headroom;
1004         int new_headroom;
1005         int headroom;
1006         int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1007         int udp_len;
1008
1009         /* Check that there's enough headroom in the skb to insert IP,
1010          * UDP and L2TP headers. If not enough, expand it to
1011          * make room. Adjust truesize.
1012          */
1013         headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1014                 uhlen + hdr_len;
1015         old_headroom = skb_headroom(skb);
1016         if (skb_cow_head(skb, headroom))
1017                 goto abort;
1018
1019         new_headroom = skb_headroom(skb);
1020         skb_orphan(skb);
1021         skb->truesize += new_headroom - old_headroom;
1022
1023         /* Setup L2TP header */
1024         session->build_header(session, __skb_push(skb, hdr_len));
1025
1026         /* Reset skb netfilter state */
1027         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1028         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1029                               IPSKB_REROUTED);
1030         nf_reset(skb);
1031
1032         /* Get routing info from the tunnel socket */
1033         skb_dst_drop(skb);
1034         skb_dst_set(skb, dst_clone(__sk_dst_get(sk)));
1035
1036         switch (tunnel->encap) {
1037         case L2TP_ENCAPTYPE_UDP:
1038                 /* Setup UDP header */
1039                 inet = inet_sk(sk);
1040                 __skb_push(skb, sizeof(*uh));
1041                 skb_reset_transport_header(skb);
1042                 uh = udp_hdr(skb);
1043                 uh->source = inet->inet_sport;
1044                 uh->dest = inet->inet_dport;
1045                 udp_len = uhlen + hdr_len + data_len;
1046                 uh->len = htons(udp_len);
1047                 uh->check = 0;
1048
1049                 /* Calculate UDP checksum if configured to do so */
1050                 if (sk->sk_no_check == UDP_CSUM_NOXMIT)
1051                         skb->ip_summed = CHECKSUM_NONE;
1052                 else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
1053                          (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
1054                         skb->ip_summed = CHECKSUM_COMPLETE;
1055                         csum = skb_checksum(skb, 0, udp_len, 0);
1056                         uh->check = csum_tcpudp_magic(inet->inet_saddr,
1057                                                       inet->inet_daddr,
1058                                                       udp_len, IPPROTO_UDP, csum);
1059                         if (uh->check == 0)
1060                                 uh->check = CSUM_MANGLED_0;
1061                 } else {
1062                         skb->ip_summed = CHECKSUM_PARTIAL;
1063                         skb->csum_start = skb_transport_header(skb) - skb->head;
1064                         skb->csum_offset = offsetof(struct udphdr, check);
1065                         uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
1066                                                        inet->inet_daddr,
1067                                                        udp_len, IPPROTO_UDP, 0);
1068                 }
1069                 break;
1070
1071         case L2TP_ENCAPTYPE_IP:
1072                 break;
1073         }
1074
1075         l2tp_skb_set_owner_w(skb, sk);
1076
1077         l2tp_xmit_core(session, skb, data_len);
1078
1079 abort:
1080         return 0;
1081 }
1082 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1083
1084 /*****************************************************************************
1085  * Tinnel and session create/destroy.
1086  *****************************************************************************/
1087
1088 /* Tunnel socket destruct hook.
1089  * The tunnel context is deleted only when all session sockets have been
1090  * closed.
1091  */
1092 void l2tp_tunnel_destruct(struct sock *sk)
1093 {
1094         struct l2tp_tunnel *tunnel;
1095
1096         tunnel = sk->sk_user_data;
1097         if (tunnel == NULL)
1098                 goto end;
1099
1100         PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1101                "%s: closing...\n", tunnel->name);
1102
1103         /* Close all sessions */
1104         l2tp_tunnel_closeall(tunnel);
1105
1106         switch (tunnel->encap) {
1107         case L2TP_ENCAPTYPE_UDP:
1108                 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1109                 (udp_sk(sk))->encap_type = 0;
1110                 (udp_sk(sk))->encap_rcv = NULL;
1111                 break;
1112         case L2TP_ENCAPTYPE_IP:
1113                 break;
1114         }
1115
1116         /* Remove hooks into tunnel socket */
1117         tunnel->sock = NULL;
1118         sk->sk_destruct = tunnel->old_sk_destruct;
1119         sk->sk_user_data = NULL;
1120
1121         /* Call the original destructor */
1122         if (sk->sk_destruct)
1123                 (*sk->sk_destruct)(sk);
1124
1125         /* We're finished with the socket */
1126         l2tp_tunnel_dec_refcount(tunnel);
1127
1128 end:
1129         return;
1130 }
1131 EXPORT_SYMBOL(l2tp_tunnel_destruct);
1132
1133 /* When the tunnel is closed, all the attached sessions need to go too.
1134  */
1135 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1136 {
1137         int hash;
1138         struct hlist_node *walk;
1139         struct hlist_node *tmp;
1140         struct l2tp_session *session;
1141
1142         BUG_ON(tunnel == NULL);
1143
1144         PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1145                "%s: closing all sessions...\n", tunnel->name);
1146
1147         write_lock_bh(&tunnel->hlist_lock);
1148         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1149 again:
1150                 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1151                         session = hlist_entry(walk, struct l2tp_session, hlist);
1152
1153                         PRINTK(session->debug, L2TP_MSG_CONTROL, KERN_INFO,
1154                                "%s: closing session\n", session->name);
1155
1156                         hlist_del_init(&session->hlist);
1157
1158                         /* Since we should hold the sock lock while
1159                          * doing any unbinding, we need to release the
1160                          * lock we're holding before taking that lock.
1161                          * Hold a reference to the sock so it doesn't
1162                          * disappear as we're jumping between locks.
1163                          */
1164                         if (session->ref != NULL)
1165                                 (*session->ref)(session);
1166
1167                         write_unlock_bh(&tunnel->hlist_lock);
1168
1169                         if (tunnel->version != L2TP_HDR_VER_2) {
1170                                 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1171
1172                                 spin_lock_bh(&pn->l2tp_session_hlist_lock);
1173                                 hlist_del_init_rcu(&session->global_hlist);
1174                                 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1175                                 synchronize_rcu();
1176                         }
1177
1178                         if (session->session_close != NULL)
1179                                 (*session->session_close)(session);
1180
1181                         if (session->deref != NULL)
1182                                 (*session->deref)(session);
1183
1184                         write_lock_bh(&tunnel->hlist_lock);
1185
1186                         /* Now restart from the beginning of this hash
1187                          * chain.  We always remove a session from the
1188                          * list so we are guaranteed to make forward
1189                          * progress.
1190                          */
1191                         goto again;
1192                 }
1193         }
1194         write_unlock_bh(&tunnel->hlist_lock);
1195 }
1196 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
1197
1198 /* Really kill the tunnel.
1199  * Come here only when all sessions have been cleared from the tunnel.
1200  */
1201 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
1202 {
1203         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1204
1205         BUG_ON(atomic_read(&tunnel->ref_count) != 0);
1206         BUG_ON(tunnel->sock != NULL);
1207
1208         PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
1209                "%s: free...\n", tunnel->name);
1210
1211         /* Remove from tunnel list */
1212         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1213         list_del_rcu(&tunnel->list);
1214         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1215         synchronize_rcu();
1216
1217         atomic_dec(&l2tp_tunnel_count);
1218         kfree(tunnel);
1219 }
1220 EXPORT_SYMBOL_GPL(l2tp_tunnel_free);
1221
1222 /* Create a socket for the tunnel, if one isn't set up by
1223  * userspace. This is used for static tunnels where there is no
1224  * managing L2TP daemon.
1225  */
1226 static int l2tp_tunnel_sock_create(u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct socket **sockp)
1227 {
1228         int err = -EINVAL;
1229         struct sockaddr_in udp_addr;
1230         struct sockaddr_l2tpip ip_addr;
1231         struct socket *sock = NULL;
1232
1233         switch (cfg->encap) {
1234         case L2TP_ENCAPTYPE_UDP:
1235                 err = sock_create(AF_INET, SOCK_DGRAM, 0, sockp);
1236                 if (err < 0)
1237                         goto out;
1238
1239                 sock = *sockp;
1240
1241                 memset(&udp_addr, 0, sizeof(udp_addr));
1242                 udp_addr.sin_family = AF_INET;
1243                 udp_addr.sin_addr = cfg->local_ip;
1244                 udp_addr.sin_port = htons(cfg->local_udp_port);
1245                 err = kernel_bind(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr));
1246                 if (err < 0)
1247                         goto out;
1248
1249                 udp_addr.sin_family = AF_INET;
1250                 udp_addr.sin_addr = cfg->peer_ip;
1251                 udp_addr.sin_port = htons(cfg->peer_udp_port);
1252                 err = kernel_connect(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr), 0);
1253                 if (err < 0)
1254                         goto out;
1255
1256                 if (!cfg->use_udp_checksums)
1257                         sock->sk->sk_no_check = UDP_CSUM_NOXMIT;
1258
1259                 break;
1260
1261         case L2TP_ENCAPTYPE_IP:
1262                 err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_L2TP, sockp);
1263                 if (err < 0)
1264                         goto out;
1265
1266                 sock = *sockp;
1267
1268                 memset(&ip_addr, 0, sizeof(ip_addr));
1269                 ip_addr.l2tp_family = AF_INET;
1270                 ip_addr.l2tp_addr = cfg->local_ip;
1271                 ip_addr.l2tp_conn_id = tunnel_id;
1272                 err = kernel_bind(sock, (struct sockaddr *) &ip_addr, sizeof(ip_addr));
1273                 if (err < 0)
1274                         goto out;
1275
1276                 ip_addr.l2tp_family = AF_INET;
1277                 ip_addr.l2tp_addr = cfg->peer_ip;
1278                 ip_addr.l2tp_conn_id = peer_tunnel_id;
1279                 err = kernel_connect(sock, (struct sockaddr *) &ip_addr, sizeof(ip_addr), 0);
1280                 if (err < 0)
1281                         goto out;
1282
1283                 break;
1284
1285         default:
1286                 goto out;
1287         }
1288
1289 out:
1290         if ((err < 0) && sock) {
1291                 sock_release(sock);
1292                 *sockp = NULL;
1293         }
1294
1295         return err;
1296 }
1297
1298 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)
1299 {
1300         struct l2tp_tunnel *tunnel = NULL;
1301         int err;
1302         struct socket *sock = NULL;
1303         struct sock *sk = NULL;
1304         struct l2tp_net *pn;
1305         enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1306
1307         /* Get the tunnel socket from the fd, which was opened by
1308          * the userspace L2TP daemon. If not specified, create a
1309          * kernel socket.
1310          */
1311         if (fd < 0) {
1312                 err = l2tp_tunnel_sock_create(tunnel_id, peer_tunnel_id, cfg, &sock);
1313                 if (err < 0)
1314                         goto err;
1315         } else {
1316                 err = -EBADF;
1317                 sock = sockfd_lookup(fd, &err);
1318                 if (!sock) {
1319                         printk(KERN_ERR "tunl %hu: sockfd_lookup(fd=%d) returned %d\n",
1320                                tunnel_id, fd, err);
1321                         goto err;
1322                 }
1323         }
1324
1325         sk = sock->sk;
1326
1327         if (cfg != NULL)
1328                 encap = cfg->encap;
1329
1330         /* Quick sanity checks */
1331         switch (encap) {
1332         case L2TP_ENCAPTYPE_UDP:
1333                 err = -EPROTONOSUPPORT;
1334                 if (sk->sk_protocol != IPPROTO_UDP) {
1335                         printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1336                                tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
1337                         goto err;
1338                 }
1339                 break;
1340         case L2TP_ENCAPTYPE_IP:
1341                 err = -EPROTONOSUPPORT;
1342                 if (sk->sk_protocol != IPPROTO_L2TP) {
1343                         printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
1344                                tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
1345                         goto err;
1346                 }
1347                 break;
1348         }
1349
1350         /* Check if this socket has already been prepped */
1351         tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
1352         if (tunnel != NULL) {
1353                 /* This socket has already been prepped */
1354                 err = -EBUSY;
1355                 goto err;
1356         }
1357
1358         tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1359         if (tunnel == NULL) {
1360                 err = -ENOMEM;
1361                 goto err;
1362         }
1363
1364         tunnel->version = version;
1365         tunnel->tunnel_id = tunnel_id;
1366         tunnel->peer_tunnel_id = peer_tunnel_id;
1367         tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1368
1369         tunnel->magic = L2TP_TUNNEL_MAGIC;
1370         sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1371         rwlock_init(&tunnel->hlist_lock);
1372
1373         /* The net we belong to */
1374         tunnel->l2tp_net = net;
1375         pn = l2tp_pernet(net);
1376
1377         if (cfg != NULL)
1378                 tunnel->debug = cfg->debug;
1379
1380         /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1381         tunnel->encap = encap;
1382         if (encap == L2TP_ENCAPTYPE_UDP) {
1383                 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
1384                 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
1385                 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
1386         }
1387
1388         sk->sk_user_data = tunnel;
1389
1390         /* Hook on the tunnel socket destructor so that we can cleanup
1391          * if the tunnel socket goes away.
1392          */
1393         tunnel->old_sk_destruct = sk->sk_destruct;
1394         sk->sk_destruct = &l2tp_tunnel_destruct;
1395         tunnel->sock = sk;
1396         sk->sk_allocation = GFP_ATOMIC;
1397
1398         /* Add tunnel to our list */
1399         INIT_LIST_HEAD(&tunnel->list);
1400         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1401         list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1402         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1403         synchronize_rcu();
1404         atomic_inc(&l2tp_tunnel_count);
1405
1406         /* Bump the reference count. The tunnel context is deleted
1407          * only when this drops to zero.
1408          */
1409         l2tp_tunnel_inc_refcount(tunnel);
1410
1411         err = 0;
1412 err:
1413         if (tunnelp)
1414                 *tunnelp = tunnel;
1415
1416         /* If tunnel's socket was created by the kernel, it doesn't
1417          *  have a file.
1418          */
1419         if (sock && sock->file)
1420                 sockfd_put(sock);
1421
1422         return err;
1423 }
1424 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1425
1426 /* This function is used by the netlink TUNNEL_DELETE command.
1427  */
1428 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1429 {
1430         int err = 0;
1431         struct socket *sock = tunnel->sock ? tunnel->sock->sk_socket : NULL;
1432
1433         /* Force the tunnel socket to close. This will eventually
1434          * cause the tunnel to be deleted via the normal socket close
1435          * mechanisms when userspace closes the tunnel socket.
1436          */
1437         if (sock != NULL) {
1438                 err = inet_shutdown(sock, 2);
1439
1440                 /* If the tunnel's socket was created by the kernel,
1441                  * close the socket here since the socket was not
1442                  * created by userspace.
1443                  */
1444                 if (sock->file == NULL)
1445                         err = inet_release(sock);
1446         }
1447
1448         return err;
1449 }
1450 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1451
1452 /* Really kill the session.
1453  */
1454 void l2tp_session_free(struct l2tp_session *session)
1455 {
1456         struct l2tp_tunnel *tunnel;
1457
1458         BUG_ON(atomic_read(&session->ref_count) != 0);
1459
1460         tunnel = session->tunnel;
1461         if (tunnel != NULL) {
1462                 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1463
1464                 /* Delete the session from the hash */
1465                 write_lock_bh(&tunnel->hlist_lock);
1466                 hlist_del_init(&session->hlist);
1467                 write_unlock_bh(&tunnel->hlist_lock);
1468
1469                 /* Unlink from the global hash if not L2TPv2 */
1470                 if (tunnel->version != L2TP_HDR_VER_2) {
1471                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1472
1473                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1474                         hlist_del_init_rcu(&session->global_hlist);
1475                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1476                         synchronize_rcu();
1477                 }
1478
1479                 if (session->session_id != 0)
1480                         atomic_dec(&l2tp_session_count);
1481
1482                 sock_put(tunnel->sock);
1483
1484                 /* This will delete the tunnel context if this
1485                  * is the last session on the tunnel.
1486                  */
1487                 session->tunnel = NULL;
1488                 l2tp_tunnel_dec_refcount(tunnel);
1489         }
1490
1491         kfree(session);
1492
1493         return;
1494 }
1495 EXPORT_SYMBOL_GPL(l2tp_session_free);
1496
1497 /* This function is used by the netlink SESSION_DELETE command and by
1498    pseudowire modules.
1499  */
1500 int l2tp_session_delete(struct l2tp_session *session)
1501 {
1502         if (session->session_close != NULL)
1503                 (*session->session_close)(session);
1504
1505         l2tp_session_dec_refcount(session);
1506
1507         return 0;
1508 }
1509 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1510
1511
1512 /* We come here whenever a session's send_seq, cookie_len or
1513  * l2specific_len parameters are set.
1514  */
1515 void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1516 {
1517         if (version == L2TP_HDR_VER_2) {
1518                 session->hdr_len = 6;
1519                 if (session->send_seq)
1520                         session->hdr_len += 4;
1521         } else {
1522                 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset;
1523                 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1524                         session->hdr_len += 4;
1525         }
1526
1527 }
1528 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len);
1529
1530 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)
1531 {
1532         struct l2tp_session *session;
1533
1534         session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1535         if (session != NULL) {
1536                 session->magic = L2TP_SESSION_MAGIC;
1537                 session->tunnel = tunnel;
1538
1539                 session->session_id = session_id;
1540                 session->peer_session_id = peer_session_id;
1541                 session->nr = 1;
1542
1543                 sprintf(&session->name[0], "sess %u/%u",
1544                         tunnel->tunnel_id, session->session_id);
1545
1546                 skb_queue_head_init(&session->reorder_q);
1547
1548                 INIT_HLIST_NODE(&session->hlist);
1549                 INIT_HLIST_NODE(&session->global_hlist);
1550
1551                 /* Inherit debug options from tunnel */
1552                 session->debug = tunnel->debug;
1553
1554                 if (cfg) {
1555                         session->pwtype = cfg->pw_type;
1556                         session->debug = cfg->debug;
1557                         session->mtu = cfg->mtu;
1558                         session->mru = cfg->mru;
1559                         session->send_seq = cfg->send_seq;
1560                         session->recv_seq = cfg->recv_seq;
1561                         session->lns_mode = cfg->lns_mode;
1562                         session->reorder_timeout = cfg->reorder_timeout;
1563                         session->offset = cfg->offset;
1564                         session->l2specific_type = cfg->l2specific_type;
1565                         session->l2specific_len = cfg->l2specific_len;
1566                         session->cookie_len = cfg->cookie_len;
1567                         memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1568                         session->peer_cookie_len = cfg->peer_cookie_len;
1569                         memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1570                 }
1571
1572                 if (tunnel->version == L2TP_HDR_VER_2)
1573                         session->build_header = l2tp_build_l2tpv2_header;
1574                 else
1575                         session->build_header = l2tp_build_l2tpv3_header;
1576
1577                 l2tp_session_set_header_len(session, tunnel->version);
1578
1579                 /* Bump the reference count. The session context is deleted
1580                  * only when this drops to zero.
1581                  */
1582                 l2tp_session_inc_refcount(session);
1583                 l2tp_tunnel_inc_refcount(tunnel);
1584
1585                 /* Ensure tunnel socket isn't deleted */
1586                 sock_hold(tunnel->sock);
1587
1588                 /* Add session to the tunnel's hash list */
1589                 write_lock_bh(&tunnel->hlist_lock);
1590                 hlist_add_head(&session->hlist,
1591                                l2tp_session_id_hash(tunnel, session_id));
1592                 write_unlock_bh(&tunnel->hlist_lock);
1593
1594                 /* And to the global session list if L2TPv3 */
1595                 if (tunnel->version != L2TP_HDR_VER_2) {
1596                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1597
1598                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1599                         hlist_add_head_rcu(&session->global_hlist,
1600                                            l2tp_session_id_hash_2(pn, session_id));
1601                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1602                         synchronize_rcu();
1603                 }
1604
1605                 /* Ignore management session in session count value */
1606                 if (session->session_id != 0)
1607                         atomic_inc(&l2tp_session_count);
1608         }
1609
1610         return session;
1611 }
1612 EXPORT_SYMBOL_GPL(l2tp_session_create);
1613
1614 /*****************************************************************************
1615  * Init and cleanup
1616  *****************************************************************************/
1617
1618 static __net_init int l2tp_init_net(struct net *net)
1619 {
1620         struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1621         int hash;
1622
1623         INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1624         spin_lock_init(&pn->l2tp_tunnel_list_lock);
1625
1626         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1627                 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1628
1629         spin_lock_init(&pn->l2tp_session_hlist_lock);
1630
1631         return 0;
1632 }
1633
1634 static struct pernet_operations l2tp_net_ops = {
1635         .init = l2tp_init_net,
1636         .id   = &l2tp_net_id,
1637         .size = sizeof(struct l2tp_net),
1638 };
1639
1640 static int __init l2tp_init(void)
1641 {
1642         int rc = 0;
1643
1644         rc = register_pernet_device(&l2tp_net_ops);
1645         if (rc)
1646                 goto out;
1647
1648         printk(KERN_INFO "L2TP core driver, %s\n", L2TP_DRV_VERSION);
1649
1650 out:
1651         return rc;
1652 }
1653
1654 static void __exit l2tp_exit(void)
1655 {
1656         unregister_pernet_device(&l2tp_net_ops);
1657 }
1658
1659 module_init(l2tp_init);
1660 module_exit(l2tp_exit);
1661
1662 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1663 MODULE_DESCRIPTION("L2TP core");
1664 MODULE_LICENSE("GPL");
1665 MODULE_VERSION(L2TP_DRV_VERSION);
1666