net/l2tp/l2tp_ip6.c

   1 /*
   2  * L2TPv3 IP encapsulation support for IPv6
   3  *
   4  * Copyright (c) 2012 Katalix Systems Ltd
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/icmp.h>
  15 #include <linux/module.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/random.h>
  18 #include <linux/socket.h>
  19 #include <linux/l2tp.h>
  20 #include <linux/in.h>
  21 #include <linux/in6.h>
  22 #include <net/sock.h>
  23 #include <net/ip.h>
  24 #include <net/icmp.h>
  25 #include <net/udp.h>
  26 #include <net/inet_common.h>
  27 #include <net/inet_hashtables.h>
  28 #include <net/tcp_states.h>
  29 #include <net/protocol.h>
  30 #include <net/xfrm.h>
  31
  32 #include <net/transp_v6.h>
  33 #include <net/addrconf.h>
  34 #include <net/ip6_route.h>
  35
  36 #include "l2tp_core.h"
  37
  38 struct l2tp_ip6_sock {
  39         /* inet_sock has to be the first member of l2tp_ip6_sock */
  40         struct inet_sock        inet;
  41
  42         u32                     conn_id;
  43         u32                     peer_conn_id;
  44
  45         /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
  46            inet6_sk_generic */
  47         struct ipv6_pinfo       inet6;
  48 };
  49
  50 static DEFINE_RWLOCK(l2tp_ip6_lock);
  51 static struct hlist_head l2tp_ip6_table;
  52 static struct hlist_head l2tp_ip6_bind_table;
  53
  54 static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
  55 {
  56         return (struct l2tp_ip6_sock *)sk;
  57 }
  58
  59 static struct sock *__l2tp_ip6_bind_lookup(struct net *net,
  60                                            struct in6_addr *laddr,
  61                                            int dif, u32 tunnel_id)
  62 {
  63         struct hlist_node *node;
  64         struct sock *sk;
  65
  66         sk_for_each_bound(sk, node, &l2tp_ip6_bind_table) {
  67                 struct in6_addr *addr = inet6_rcv_saddr(sk);
  68                 struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
  69
  70                 if (l2tp == NULL)
  71                         continue;
  72
  73                 if ((l2tp->conn_id == tunnel_id) &&
  74                     net_eq(sock_net(sk), net) &&
  75                     !(addr && ipv6_addr_equal(addr, laddr)) &&
  76                     !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif))
  77                         goto found;
  78         }
  79
  80         sk = NULL;
  81 found:
  82         return sk;
  83 }
  84
  85 static inline struct sock *l2tp_ip6_bind_lookup(struct net *net,
  86                                                 struct in6_addr *laddr,
  87                                                 int dif, u32 tunnel_id)
  88 {
  89         struct sock *sk = __l2tp_ip6_bind_lookup(net, laddr, dif, tunnel_id);
  90         if (sk)
  91                 sock_hold(sk);
  92
  93         return sk;
  94 }
  95
  96 /* When processing receive frames, there are two cases to
  97  * consider. Data frames consist of a non-zero session-id and an
  98  * optional cookie. Control frames consist of a regular L2TP header
  99  * preceded by 32-bits of zeros.
 100  *
 101  * L2TPv3 Session Header Over IP
 102  *
 103  *  0                   1                   2                   3
 104  *  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
 105  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 106  * |                           Session ID                          |
 107  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 108  * |               Cookie (optional, maximum 64 bits)...
 109  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 110  *                                                                 |
 111  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 112  *
 113  * L2TPv3 Control Message Header Over IP
 114  *
 115  *  0                   1                   2                   3
 116  *  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
 117  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 118  * |                      (32 bits of zeros)                       |
 119  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 120  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
 121  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 122  * |                     Control Connection ID                     |
 123  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 124  * |               Ns              |               Nr              |
 125  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 126  *
 127  * All control frames are passed to userspace.
 128  */
 129 static int l2tp_ip6_recv(struct sk_buff *skb)
 130 {
 131         struct sock *sk;
 132         u32 session_id;
 133         u32 tunnel_id;
 134         unsigned char *ptr, *optr;
 135         struct l2tp_session *session;
 136         struct l2tp_tunnel *tunnel = NULL;
 137         int length;
 138
 139         /* Point to L2TP header */
 140         optr = ptr = skb->data;
 141
 142         if (!pskb_may_pull(skb, 4))
 143                 goto discard;
 144
 145         session_id = ntohl(*((__be32 *) ptr));
 146         ptr += 4;
 147
 148         /* RFC3931: L2TP/IP packets have the first 4 bytes containing
 149          * the session_id. If it is 0, the packet is a L2TP control
 150          * frame and the session_id value can be discarded.
 151          */
 152         if (session_id == 0) {
 153                 __skb_pull(skb, 4);
 154                 goto pass_up;
 155         }
 156
 157         /* Ok, this is a data packet. Lookup the session. */
 158         session = l2tp_session_find(&init_net, NULL, session_id);
 159         if (session == NULL)
 160                 goto discard;
 161
 162         tunnel = session->tunnel;
 163         if (tunnel == NULL)
 164                 goto discard;
 165
 166         /* Trace packet contents, if enabled */
 167         if (tunnel->debug & L2TP_MSG_DATA) {
 168                 length = min(32u, skb->len);
 169                 if (!pskb_may_pull(skb, length))
 170                         goto discard;
 171
 172                 pr_debug("%s: ip recv\n", tunnel->name);
 173                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
 174         }
 175
 176         l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
 177                          tunnel->recv_payload_hook);
 178         return 0;
 179
 180 pass_up:
 181         /* Get the tunnel_id from the L2TP header */
 182         if (!pskb_may_pull(skb, 12))
 183                 goto discard;
 184
 185         if ((skb->data[0] & 0xc0) != 0xc0)
 186                 goto discard;
 187
 188         tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
 189         tunnel = l2tp_tunnel_find(&init_net, tunnel_id);
 190         if (tunnel != NULL)
 191                 sk = tunnel->sock;
 192         else {
 193                 struct ipv6hdr *iph = ipv6_hdr(skb);
 194
 195                 read_lock_bh(&l2tp_ip6_lock);
 196                 sk = __l2tp_ip6_bind_lookup(&init_net, &iph->daddr,
 197                                             0, tunnel_id);
 198                 read_unlock_bh(&l2tp_ip6_lock);
 199         }
 200
 201         if (sk == NULL)
 202                 goto discard;
 203
 204         sock_hold(sk);
 205
 206         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
 207                 goto discard_put;
 208
 209         nf_reset(skb);
 210
 211         return sk_receive_skb(sk, skb, 1);
 212
 213 discard_put:
 214         sock_put(sk);
 215
 216 discard:
 217         kfree_skb(skb);
 218         return 0;
 219 }
 220
 221 static int l2tp_ip6_open(struct sock *sk)
 222 {
 223         /* Prevent autobind. We don't have ports. */
 224         inet_sk(sk)->inet_num = IPPROTO_L2TP;
 225
 226         write_lock_bh(&l2tp_ip6_lock);
 227         sk_add_node(sk, &l2tp_ip6_table);
 228         write_unlock_bh(&l2tp_ip6_lock);
 229
 230         return 0;
 231 }
 232
 233 static void l2tp_ip6_close(struct sock *sk, long timeout)
 234 {
 235         write_lock_bh(&l2tp_ip6_lock);
 236         hlist_del_init(&sk->sk_bind_node);
 237         sk_del_node_init(sk);
 238         write_unlock_bh(&l2tp_ip6_lock);
 239
 240         sk_common_release(sk);
 241 }
 242
 243 static void l2tp_ip6_destroy_sock(struct sock *sk)
 244 {
 245         lock_sock(sk);
 246         ip6_flush_pending_frames(sk);
 247         release_sock(sk);
 248
 249         inet6_destroy_sock(sk);
 250 }
 251
 252 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 253 {
 254         struct inet_sock *inet = inet_sk(sk);
 255         struct ipv6_pinfo *np = inet6_sk(sk);
 256         struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
 257         __be32 v4addr = 0;
 258         int addr_type;
 259         int err;
 260
 261         if (!sock_flag(sk, SOCK_ZAPPED))
 262                 return -EINVAL;
 263         if (addr->l2tp_family != AF_INET6)
 264                 return -EINVAL;
 265         if (addr_len < sizeof(*addr))
 266                 return -EINVAL;
 267
 268         addr_type = ipv6_addr_type(&addr->l2tp_addr);
 269
 270         /* l2tp_ip6 sockets are IPv6 only */
 271         if (addr_type == IPV6_ADDR_MAPPED)
 272                 return -EADDRNOTAVAIL;
 273
 274         /* L2TP is point-point, not multicast */
 275         if (addr_type & IPV6_ADDR_MULTICAST)
 276                 return -EADDRNOTAVAIL;
 277
 278         err = -EADDRINUSE;
 279         read_lock_bh(&l2tp_ip6_lock);
 280         if (__l2tp_ip6_bind_lookup(&init_net, &addr->l2tp_addr,
 281                                    sk->sk_bound_dev_if, addr->l2tp_conn_id))
 282                 goto out_in_use;
 283         read_unlock_bh(&l2tp_ip6_lock);
 284
 285         lock_sock(sk);
 286
 287         err = -EINVAL;
 288         if (sk->sk_state != TCP_CLOSE)
 289                 goto out_unlock;
 290
 291         /* Check if the address belongs to the host. */
 292         rcu_read_lock();
 293         if (addr_type != IPV6_ADDR_ANY) {
 294                 struct net_device *dev = NULL;
 295
 296                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 297                         if (addr_len >= sizeof(struct sockaddr_in6) &&
 298                             addr->l2tp_scope_id) {
 299                                 /* Override any existing binding, if another
 300                                  * one is supplied by user.
 301                                  */
 302                                 sk->sk_bound_dev_if = addr->l2tp_scope_id;
 303                         }
 304
 305                         /* Binding to link-local address requires an
 306                            interface */
 307                         if (!sk->sk_bound_dev_if)
 308                                 goto out_unlock_rcu;
 309
 310                         err = -ENODEV;
 311                         dev = dev_get_by_index_rcu(sock_net(sk),
 312                                                    sk->sk_bound_dev_if);
 313                         if (!dev)
 314                                 goto out_unlock_rcu;
 315                 }
 316
 317                 /* ipv4 addr of the socket is invalid.  Only the
 318                  * unspecified and mapped address have a v4 equivalent.
 319                  */
 320                 v4addr = LOOPBACK4_IPV6;
 321                 err = -EADDRNOTAVAIL;
 322                 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
 323                         goto out_unlock_rcu;
 324         }
 325         rcu_read_unlock();
 326
 327         inet->inet_rcv_saddr = inet->inet_saddr = v4addr;
 328         np->rcv_saddr = addr->l2tp_addr;
 329         np->saddr = addr->l2tp_addr;
 330
 331         l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
 332
 333         write_lock_bh(&l2tp_ip6_lock);
 334         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 335         sk_del_node_init(sk);
 336         write_unlock_bh(&l2tp_ip6_lock);
 337
 338         sock_reset_flag(sk, SOCK_ZAPPED);
 339         release_sock(sk);
 340         return 0;
 341
 342 out_unlock_rcu:
 343         rcu_read_unlock();
 344 out_unlock:
 345         release_sock(sk);
 346         return err;
 347
 348 out_in_use:
 349         read_unlock_bh(&l2tp_ip6_lock);
 350         return err;
 351 }
 352
 353 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
 354                             int addr_len)
 355 {
 356         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
 357         struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
 358         struct in6_addr *daddr;
 359         int     addr_type;
 360         int rc;
 361
 362         if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
 363                 return -EINVAL;
 364
 365         if (addr_len < sizeof(*lsa))
 366                 return -EINVAL;
 367
 368         addr_type = ipv6_addr_type(&usin->sin6_addr);
 369         if (addr_type & IPV6_ADDR_MULTICAST)
 370                 return -EINVAL;
 371
 372         if (addr_type & IPV6_ADDR_MAPPED) {
 373                 daddr = &usin->sin6_addr;
 374                 if (ipv4_is_multicast(daddr->s6_addr32[3]))
 375                         return -EINVAL;
 376         }
 377
 378         rc = ip6_datagram_connect(sk, uaddr, addr_len);
 379
 380         lock_sock(sk);
 381
 382         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 383
 384         write_lock_bh(&l2tp_ip6_lock);
 385         hlist_del_init(&sk->sk_bind_node);
 386         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 387         write_unlock_bh(&l2tp_ip6_lock);
 388
 389         release_sock(sk);
 390
 391         return rc;
 392 }
 393
 394 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
 395 {
 396         if (sock_flag(sk, SOCK_ZAPPED))
 397                 return 0;
 398
 399         return udp_disconnect(sk, flags);
 400 }
 401
 402 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
 403                             int *uaddr_len, int peer)
 404 {
 405         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
 406         struct sock *sk = sock->sk;
 407         struct ipv6_pinfo *np = inet6_sk(sk);
 408         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
 409
 410         lsa->l2tp_family = AF_INET6;
 411         lsa->l2tp_flowinfo = 0;
 412         lsa->l2tp_scope_id = 0;
 413         lsa->l2tp_unused = 0;
 414         if (peer) {
 415                 if (!lsk->peer_conn_id)
 416                         return -ENOTCONN;
 417                 lsa->l2tp_conn_id = lsk->peer_conn_id;
 418                 lsa->l2tp_addr = np->daddr;
 419                 if (np->sndflow)
 420                         lsa->l2tp_flowinfo = np->flow_label;
 421         } else {
 422                 if (ipv6_addr_any(&np->rcv_saddr))
 423                         lsa->l2tp_addr = np->saddr;
 424                 else
 425                         lsa->l2tp_addr = np->rcv_saddr;
 426
 427                 lsa->l2tp_conn_id = lsk->conn_id;
 428         }
 429         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 430                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
 431         *uaddr_len = sizeof(*lsa);
 432         return 0;
 433 }
 434
 435 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
 436 {
 437         int rc;
 438
 439         /* Charge it to the socket, dropping if the queue is full. */
 440         rc = sock_queue_rcv_skb(sk, skb);
 441         if (rc < 0)
 442                 goto drop;
 443
 444         return 0;
 445
 446 drop:
 447         IP_INC_STATS(&init_net, IPSTATS_MIB_INDISCARDS);
 448         kfree_skb(skb);
 449         return -1;
 450 }
 451
 452 static int l2tp_ip6_push_pending_frames(struct sock *sk)
 453 {
 454         struct sk_buff *skb;
 455         __be32 *transhdr = NULL;
 456         int err = 0;
 457
 458         skb = skb_peek(&sk->sk_write_queue);
 459         if (skb == NULL)
 460                 goto out;
 461
 462         transhdr = (__be32 *)skb_transport_header(skb);
 463         *transhdr = 0;
 464
 465         err = ip6_push_pending_frames(sk);
 466
 467 out:
 468         return err;
 469 }
 470
 471 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
 472  * control frames.
 473  */
 474 static int l2tp_ip6_sendmsg(struct kiocb *iocb, struct sock *sk,
 475                             struct msghdr *msg, size_t len)
 476 {
 477         struct ipv6_txoptions opt_space;
 478         struct sockaddr_l2tpip6 *lsa =
 479                 (struct sockaddr_l2tpip6 *) msg->msg_name;
 480         struct in6_addr *daddr, *final_p, final;
 481         struct ipv6_pinfo *np = inet6_sk(sk);
 482         struct ipv6_txoptions *opt = NULL;
 483         struct ip6_flowlabel *flowlabel = NULL;
 484         struct dst_entry *dst = NULL;
 485         struct flowi6 fl6;
 486         int addr_len = msg->msg_namelen;
 487         int hlimit = -1;
 488         int tclass = -1;
 489         int dontfrag = -1;
 490         int transhdrlen = 4; /* zero session-id */
 491         int ulen = len + transhdrlen;
 492         int err;
 493
 494         /* Rough check on arithmetic overflow,
 495            better check is made in ip6_append_data().
 496          */
 497         if (len > INT_MAX)
 498                 return -EMSGSIZE;
 499
 500         /* Mirror BSD error message compatibility */
 501         if (msg->msg_flags & MSG_OOB)
 502                 return -EOPNOTSUPP;
 503
 504         /*
 505          *      Get and verify the address.
 506          */
 507         memset(&fl6, 0, sizeof(fl6));
 508
 509         fl6.flowi6_mark = sk->sk_mark;
 510
 511         if (lsa) {
 512                 if (addr_len < SIN6_LEN_RFC2133)
 513                         return -EINVAL;
 514
 515                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
 516                         return -EAFNOSUPPORT;
 517
 518                 daddr = &lsa->l2tp_addr;
 519                 if (np->sndflow) {
 520                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
 521                         if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
 522                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 523                                 if (flowlabel == NULL)
 524                                         return -EINVAL;
 525                                 daddr = &flowlabel->dst;
 526                         }
 527                 }
 528
 529                 /*
 530                  * Otherwise it will be difficult to maintain
 531                  * sk->sk_dst_cache.
 532                  */
 533                 if (sk->sk_state == TCP_ESTABLISHED &&
 534                     ipv6_addr_equal(daddr, &np->daddr))
 535                         daddr = &np->daddr;
 536
 537                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 538                     lsa->l2tp_scope_id &&
 539                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
 540                         fl6.flowi6_oif = lsa->l2tp_scope_id;
 541         } else {
 542                 if (sk->sk_state != TCP_ESTABLISHED)
 543                         return -EDESTADDRREQ;
 544
 545                 daddr = &np->daddr;
 546                 fl6.flowlabel = np->flow_label;
 547         }
 548
 549         if (fl6.flowi6_oif == 0)
 550                 fl6.flowi6_oif = sk->sk_bound_dev_if;
 551
 552         if (msg->msg_controllen) {
 553                 opt = &opt_space;
 554                 memset(opt, 0, sizeof(struct ipv6_txoptions));
 555                 opt->tot_len = sizeof(struct ipv6_txoptions);
 556
 557                 err = datagram_send_ctl(sock_net(sk), sk, msg, &fl6, opt,
 558                                         &hlimit, &tclass, &dontfrag);
 559                 if (err < 0) {
 560                         fl6_sock_release(flowlabel);
 561                         return err;
 562                 }
 563                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
 564                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 565                         if (flowlabel == NULL)
 566                                 return -EINVAL;
 567                 }
 568                 if (!(opt->opt_nflen|opt->opt_flen))
 569                         opt = NULL;
 570         }
 571
 572         if (opt == NULL)
 573                 opt = np->opt;
 574         if (flowlabel)
 575                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
 576         opt = ipv6_fixup_options(&opt_space, opt);
 577
 578         fl6.flowi6_proto = sk->sk_protocol;
 579         if (!ipv6_addr_any(daddr))
 580                 fl6.daddr = *daddr;
 581         else
 582                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
 583         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
 584                 fl6.saddr = np->saddr;
 585
 586         final_p = fl6_update_dst(&fl6, opt, &final);
 587
 588         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 589                 fl6.flowi6_oif = np->mcast_oif;
 590         else if (!fl6.flowi6_oif)
 591                 fl6.flowi6_oif = np->ucast_oif;
 592
 593         security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 594
 595         dst = ip6_dst_lookup_flow(sk, &fl6, final_p, true);
 596         if (IS_ERR(dst)) {
 597                 err = PTR_ERR(dst);
 598                 goto out;
 599         }
 600
 601         if (hlimit < 0) {
 602                 if (ipv6_addr_is_multicast(&fl6.daddr))
 603                         hlimit = np->mcast_hops;
 604                 else
 605                         hlimit = np->hop_limit;
 606                 if (hlimit < 0)
 607                         hlimit = ip6_dst_hoplimit(dst);
 608         }
 609
 610         if (tclass < 0)
 611                 tclass = np->tclass;
 612
 613         if (dontfrag < 0)
 614                 dontfrag = np->dontfrag;
 615
 616         if (msg->msg_flags & MSG_CONFIRM)
 617                 goto do_confirm;
 618
 619 back_from_confirm:
 620         lock_sock(sk);
 621         err = ip6_append_data(sk, ip_generic_getfrag, msg->msg_iov,
 622                               ulen, transhdrlen, hlimit, tclass, opt,
 623                               &fl6, (struct rt6_info *)dst,
 624                               msg->msg_flags, dontfrag);
 625         if (err)
 626                 ip6_flush_pending_frames(sk);
 627         else if (!(msg->msg_flags & MSG_MORE))
 628                 err = l2tp_ip6_push_pending_frames(sk);
 629         release_sock(sk);
 630 done:
 631         dst_release(dst);
 632 out:
 633         fl6_sock_release(flowlabel);
 634
 635         return err < 0 ? err : len;
 636
 637 do_confirm:
 638         dst_confirm(dst);
 639         if (!(msg->msg_flags & MSG_PROBE) || len)
 640                 goto back_from_confirm;
 641         err = 0;
 642         goto done;
 643 }
 644
 645 static int l2tp_ip6_recvmsg(struct kiocb *iocb, struct sock *sk,
 646                             struct msghdr *msg, size_t len, int noblock,
 647                             int flags, int *addr_len)
 648 {
 649         struct inet_sock *inet = inet_sk(sk);
 650         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)msg->msg_name;
 651         size_t copied = 0;
 652         int err = -EOPNOTSUPP;
 653         struct sk_buff *skb;
 654
 655         if (flags & MSG_OOB)
 656                 goto out;
 657
 658         if (addr_len)
 659                 *addr_len = sizeof(*lsa);
 660
 661         if (flags & MSG_ERRQUEUE)
 662                 return ipv6_recv_error(sk, msg, len);
 663
 664         skb = skb_recv_datagram(sk, flags, noblock, &err);
 665         if (!skb)
 666                 goto out;
 667
 668         copied = skb->len;
 669         if (len < copied) {
 670                 msg->msg_flags |= MSG_TRUNC;
 671                 copied = len;
 672         }
 673
 674         err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
 675         if (err)
 676                 goto done;
 677
 678         sock_recv_timestamp(msg, sk, skb);
 679
 680         /* Copy the address. */
 681         if (lsa) {
 682                 lsa->l2tp_family = AF_INET6;
 683                 lsa->l2tp_unused = 0;
 684                 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
 685                 lsa->l2tp_flowinfo = 0;
 686                 lsa->l2tp_scope_id = 0;
 687                 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 688                         lsa->l2tp_scope_id = IP6CB(skb)->iif;
 689         }
 690
 691         if (inet->cmsg_flags)
 692                 ip_cmsg_recv(msg, skb);
 693
 694         if (flags & MSG_TRUNC)
 695                 copied = skb->len;
 696 done:
 697         skb_free_datagram(sk, skb);
 698 out:
 699         return err ? err : copied;
 700 }
 701
 702 static struct proto l2tp_ip6_prot = {
 703         .name              = "L2TP/IPv6",
 704         .owner             = THIS_MODULE,
 705         .init              = l2tp_ip6_open,
 706         .close             = l2tp_ip6_close,
 707         .bind              = l2tp_ip6_bind,
 708         .connect           = l2tp_ip6_connect,
 709         .disconnect        = l2tp_ip6_disconnect,
 710         .ioctl             = udp_ioctl,
 711         .destroy           = l2tp_ip6_destroy_sock,
 712         .setsockopt        = ipv6_setsockopt,
 713         .getsockopt        = ipv6_getsockopt,
 714         .sendmsg           = l2tp_ip6_sendmsg,
 715         .recvmsg           = l2tp_ip6_recvmsg,
 716         .backlog_rcv       = l2tp_ip6_backlog_recv,
 717         .hash              = inet_hash,
 718         .unhash            = inet_unhash,
 719         .obj_size          = sizeof(struct l2tp_ip6_sock),
 720 #ifdef CONFIG_COMPAT
 721         .compat_setsockopt = compat_ipv6_setsockopt,
 722         .compat_getsockopt = compat_ipv6_getsockopt,
 723 #endif
 724 };
 725
 726 static const struct proto_ops l2tp_ip6_ops = {
 727         .family            = PF_INET6,
 728         .owner             = THIS_MODULE,
 729         .release           = inet6_release,
 730         .bind              = inet6_bind,
 731         .connect           = inet_dgram_connect,
 732         .socketpair        = sock_no_socketpair,
 733         .accept            = sock_no_accept,
 734         .getname           = l2tp_ip6_getname,
 735         .poll              = datagram_poll,
 736         .ioctl             = inet6_ioctl,
 737         .listen            = sock_no_listen,
 738         .shutdown          = inet_shutdown,
 739         .setsockopt        = sock_common_setsockopt,
 740         .getsockopt        = sock_common_getsockopt,
 741         .sendmsg           = inet_sendmsg,
 742         .recvmsg           = sock_common_recvmsg,
 743         .mmap              = sock_no_mmap,
 744         .sendpage          = sock_no_sendpage,
 745 #ifdef CONFIG_COMPAT
 746         .compat_setsockopt = compat_sock_common_setsockopt,
 747         .compat_getsockopt = compat_sock_common_getsockopt,
 748 #endif
 749 };
 750
 751 static struct inet_protosw l2tp_ip6_protosw = {
 752         .type           = SOCK_DGRAM,
 753         .protocol       = IPPROTO_L2TP,
 754         .prot           = &l2tp_ip6_prot,
 755         .ops            = &l2tp_ip6_ops,
 756         .no_check       = 0,
 757 };
 758
 759 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
 760         .handler        = l2tp_ip6_recv,
 761 };
 762
 763 static int __init l2tp_ip6_init(void)
 764 {
 765         int err;
 766
 767         pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
 768
 769         err = proto_register(&l2tp_ip6_prot, 1);
 770         if (err != 0)
 771                 goto out;
 772
 773         err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 774         if (err)
 775                 goto out1;
 776
 777         inet6_register_protosw(&l2tp_ip6_protosw);
 778         return 0;
 779
 780 out1:
 781         proto_unregister(&l2tp_ip6_prot);
 782 out:
 783         return err;
 784 }
 785
 786 static void __exit l2tp_ip6_exit(void)
 787 {
 788         inet6_unregister_protosw(&l2tp_ip6_protosw);
 789         inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 790         proto_unregister(&l2tp_ip6_prot);
 791 }
 792
 793 module_init(l2tp_ip6_init);
 794 module_exit(l2tp_ip6_exit);
 795
 796 MODULE_LICENSE("GPL");
 797 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
 798 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
 799 MODULE_VERSION("1.0");
 800
 801 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 802  * enums
 803  */
 804 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);