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/inet6_hashtables.h>
  29 #include <net/tcp_states.h>
  30 #include <net/protocol.h>
  31 #include <net/xfrm.h>
  32
  33 #include <net/transp_v6.h>
  34 #include <net/addrconf.h>
  35 #include <net/ip6_route.h>
  36
  37 #include "l2tp_core.h"
  38
  39 struct l2tp_ip6_sock {
  40         /* inet_sock has to be the first member of l2tp_ip6_sock */
  41         struct inet_sock        inet;
  42
  43         u32                     conn_id;
  44         u32                     peer_conn_id;
  45
  46         /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
  47            inet6_sk_generic */
  48         struct ipv6_pinfo       inet6;
  49 };
  50
  51 static DEFINE_RWLOCK(l2tp_ip6_lock);
  52 static struct hlist_head l2tp_ip6_table;
  53 static struct hlist_head l2tp_ip6_bind_table;
  54
  55 static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
  56 {
  57         return (struct l2tp_ip6_sock *)sk;
  58 }
  59
  60 static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
  61                                            const struct in6_addr *laddr,
  62                                            const struct in6_addr *raddr,
  63                                            int dif, u32 tunnel_id)
  64 {
  65         struct sock *sk;
  66
  67         sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
  68                 const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
  69                 const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
  70                 const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
  71
  72                 if (!net_eq(sock_net(sk), net))
  73                         continue;
  74
  75                 if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
  76                         continue;
  77
  78                 if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
  79                     !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
  80                         continue;
  81
  82                 if (!ipv6_addr_any(sk_raddr) && raddr &&
  83                     !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
  84                         continue;
  85
  86                 if (l2tp->conn_id != tunnel_id)
  87                         continue;
  88
  89                 goto found;
  90         }
  91
  92         sk = NULL;
  93 found:
  94         return sk;
  95 }
  96
  97 /* When processing receive frames, there are two cases to
  98  * consider. Data frames consist of a non-zero session-id and an
  99  * optional cookie. Control frames consist of a regular L2TP header
 100  * preceded by 32-bits of zeros.
 101  *
 102  * L2TPv3 Session Header Over IP
 103  *
 104  *  0                   1                   2                   3
 105  *  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
 106  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 107  * |                           Session ID                          |
 108  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 109  * |               Cookie (optional, maximum 64 bits)...
 110  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 111  *                                                                 |
 112  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 113  *
 114  * L2TPv3 Control Message Header Over IP
 115  *
 116  *  0                   1                   2                   3
 117  *  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
 118  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 119  * |                      (32 bits of zeros)                       |
 120  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 121  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
 122  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 123  * |                     Control Connection ID                     |
 124  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 125  * |               Ns              |               Nr              |
 126  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 127  *
 128  * All control frames are passed to userspace.
 129  */
 130 static int l2tp_ip6_recv(struct sk_buff *skb)
 131 {
 132         struct net *net = dev_net(skb->dev);
 133         struct sock *sk;
 134         u32 session_id;
 135         u32 tunnel_id;
 136         unsigned char *ptr, *optr;
 137         struct l2tp_session *session;
 138         struct l2tp_tunnel *tunnel = NULL;
 139         struct ipv6hdr *iph;
 140         int length;
 141
 142         if (!pskb_may_pull(skb, 4))
 143                 goto discard;
 144
 145         /* Point to L2TP header */
 146         optr = ptr = skb->data;
 147         session_id = ntohl(*((__be32 *) ptr));
 148         ptr += 4;
 149
 150         /* RFC3931: L2TP/IP packets have the first 4 bytes containing
 151          * the session_id. If it is 0, the packet is a L2TP control
 152          * frame and the session_id value can be discarded.
 153          */
 154         if (session_id == 0) {
 155                 __skb_pull(skb, 4);
 156                 goto pass_up;
 157         }
 158
 159         /* Ok, this is a data packet. Lookup the session. */
 160         session = l2tp_session_get(net, NULL, session_id);
 161         if (!session)
 162                 goto discard;
 163
 164         tunnel = session->tunnel;
 165         if (!tunnel)
 166                 goto discard_sess;
 167
 168         /* Trace packet contents, if enabled */
 169         if (tunnel->debug & L2TP_MSG_DATA) {
 170                 length = min(32u, skb->len);
 171                 if (!pskb_may_pull(skb, length))
 172                         goto discard_sess;
 173
 174                 /* Point to L2TP header */
 175                 optr = ptr = skb->data;
 176                 ptr += 4;
 177                 pr_debug("%s: ip recv\n", tunnel->name);
 178                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
 179         }
 180
 181         l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
 182                          tunnel->recv_payload_hook);
 183         l2tp_session_dec_refcount(session);
 184
 185         return 0;
 186
 187 pass_up:
 188         /* Get the tunnel_id from the L2TP header */
 189         if (!pskb_may_pull(skb, 12))
 190                 goto discard;
 191
 192         if ((skb->data[0] & 0xc0) != 0xc0)
 193                 goto discard;
 194
 195         tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
 196         iph = ipv6_hdr(skb);
 197
 198         read_lock_bh(&l2tp_ip6_lock);
 199         sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
 200                                     inet6_iif(skb), tunnel_id);
 201         if (!sk) {
 202                 read_unlock_bh(&l2tp_ip6_lock);
 203                 goto discard;
 204         }
 205         sock_hold(sk);
 206         read_unlock_bh(&l2tp_ip6_lock);
 207
 208         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
 209                 goto discard_put;
 210
 211         nf_reset(skb);
 212
 213         return sk_receive_skb(sk, skb, 1);
 214
 215 discard_sess:
 216         l2tp_session_dec_refcount(session);
 217         goto discard;
 218
 219 discard_put:
 220         sock_put(sk);
 221
 222 discard:
 223         kfree_skb(skb);
 224         return 0;
 225 }
 226
 227 static int l2tp_ip6_open(struct sock *sk)
 228 {
 229         /* Prevent autobind. We don't have ports. */
 230         inet_sk(sk)->inet_num = IPPROTO_L2TP;
 231
 232         write_lock_bh(&l2tp_ip6_lock);
 233         sk_add_node(sk, &l2tp_ip6_table);
 234         write_unlock_bh(&l2tp_ip6_lock);
 235
 236         return 0;
 237 }
 238
 239 static void l2tp_ip6_close(struct sock *sk, long timeout)
 240 {
 241         write_lock_bh(&l2tp_ip6_lock);
 242         hlist_del_init(&sk->sk_bind_node);
 243         sk_del_node_init(sk);
 244         write_unlock_bh(&l2tp_ip6_lock);
 245
 246         sk_common_release(sk);
 247 }
 248
 249 static void l2tp_ip6_destroy_sock(struct sock *sk)
 250 {
 251         struct l2tp_tunnel *tunnel = sk->sk_user_data;
 252
 253         lock_sock(sk);
 254         ip6_flush_pending_frames(sk);
 255         release_sock(sk);
 256
 257         if (tunnel)
 258                 l2tp_tunnel_delete(tunnel);
 259
 260         inet6_destroy_sock(sk);
 261 }
 262
 263 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 264 {
 265         struct inet_sock *inet = inet_sk(sk);
 266         struct ipv6_pinfo *np = inet6_sk(sk);
 267         struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
 268         struct net *net = sock_net(sk);
 269         __be32 v4addr = 0;
 270         int bound_dev_if;
 271         int addr_type;
 272         int err;
 273
 274         if (addr->l2tp_family != AF_INET6)
 275                 return -EINVAL;
 276         if (addr_len < sizeof(*addr))
 277                 return -EINVAL;
 278
 279         addr_type = ipv6_addr_type(&addr->l2tp_addr);
 280
 281         /* l2tp_ip6 sockets are IPv6 only */
 282         if (addr_type == IPV6_ADDR_MAPPED)
 283                 return -EADDRNOTAVAIL;
 284
 285         /* L2TP is point-point, not multicast */
 286         if (addr_type & IPV6_ADDR_MULTICAST)
 287                 return -EADDRNOTAVAIL;
 288
 289         lock_sock(sk);
 290
 291         err = -EINVAL;
 292         if (!sock_flag(sk, SOCK_ZAPPED))
 293                 goto out_unlock;
 294
 295         if (sk->sk_state != TCP_CLOSE)
 296                 goto out_unlock;
 297
 298         bound_dev_if = sk->sk_bound_dev_if;
 299
 300         /* Check if the address belongs to the host. */
 301         rcu_read_lock();
 302         if (addr_type != IPV6_ADDR_ANY) {
 303                 struct net_device *dev = NULL;
 304
 305                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 306                         if (addr->l2tp_scope_id)
 307                                 bound_dev_if = addr->l2tp_scope_id;
 308
 309                         /* Binding to link-local address requires an
 310                          * interface.
 311                          */
 312                         if (!bound_dev_if)
 313                                 goto out_unlock_rcu;
 314
 315                         err = -ENODEV;
 316                         dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
 317                         if (!dev)
 318                                 goto out_unlock_rcu;
 319                 }
 320
 321                 /* ipv4 addr of the socket is invalid.  Only the
 322                  * unspecified and mapped address have a v4 equivalent.
 323                  */
 324                 v4addr = LOOPBACK4_IPV6;
 325                 err = -EADDRNOTAVAIL;
 326                 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
 327                         goto out_unlock_rcu;
 328         }
 329         rcu_read_unlock();
 330
 331         write_lock_bh(&l2tp_ip6_lock);
 332         if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
 333                                    addr->l2tp_conn_id)) {
 334                 write_unlock_bh(&l2tp_ip6_lock);
 335                 err = -EADDRINUSE;
 336                 goto out_unlock;
 337         }
 338
 339         inet->inet_saddr = v4addr;
 340         inet->inet_rcv_saddr = v4addr;
 341         sk->sk_bound_dev_if = bound_dev_if;
 342         sk->sk_v6_rcv_saddr = addr->l2tp_addr;
 343         np->saddr = addr->l2tp_addr;
 344
 345         l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
 346
 347         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 348         sk_del_node_init(sk);
 349         write_unlock_bh(&l2tp_ip6_lock);
 350
 351         sock_reset_flag(sk, SOCK_ZAPPED);
 352         release_sock(sk);
 353         return 0;
 354
 355 out_unlock_rcu:
 356         rcu_read_unlock();
 357 out_unlock:
 358         release_sock(sk);
 359
 360         return err;
 361 }
 362
 363 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
 364                             int addr_len)
 365 {
 366         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
 367         struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
 368         struct in6_addr *daddr;
 369         int     addr_type;
 370         int rc;
 371
 372         if (addr_len < sizeof(*lsa))
 373                 return -EINVAL;
 374
 375         if (usin->sin6_family != AF_INET6)
 376                 return -EINVAL;
 377
 378         addr_type = ipv6_addr_type(&usin->sin6_addr);
 379         if (addr_type & IPV6_ADDR_MULTICAST)
 380                 return -EINVAL;
 381
 382         if (addr_type & IPV6_ADDR_MAPPED) {
 383                 daddr = &usin->sin6_addr;
 384                 if (ipv4_is_multicast(daddr->s6_addr32[3]))
 385                         return -EINVAL;
 386         }
 387
 388         lock_sock(sk);
 389
 390          /* Must bind first - autobinding does not work */
 391         if (sock_flag(sk, SOCK_ZAPPED)) {
 392                 rc = -EINVAL;
 393                 goto out_sk;
 394         }
 395
 396         rc = __ip6_datagram_connect(sk, uaddr, addr_len);
 397         if (rc < 0)
 398                 goto out_sk;
 399
 400         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 401
 402         write_lock_bh(&l2tp_ip6_lock);
 403         hlist_del_init(&sk->sk_bind_node);
 404         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 405         write_unlock_bh(&l2tp_ip6_lock);
 406
 407 out_sk:
 408         release_sock(sk);
 409
 410         return rc;
 411 }
 412
 413 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
 414 {
 415         if (sock_flag(sk, SOCK_ZAPPED))
 416                 return 0;
 417
 418         return __udp_disconnect(sk, flags);
 419 }
 420
 421 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
 422                             int peer)
 423 {
 424         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
 425         struct sock *sk = sock->sk;
 426         struct ipv6_pinfo *np = inet6_sk(sk);
 427         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
 428
 429         lsa->l2tp_family = AF_INET6;
 430         lsa->l2tp_flowinfo = 0;
 431         lsa->l2tp_scope_id = 0;
 432         lsa->l2tp_unused = 0;
 433         if (peer) {
 434                 if (!lsk->peer_conn_id)
 435                         return -ENOTCONN;
 436                 lsa->l2tp_conn_id = lsk->peer_conn_id;
 437                 lsa->l2tp_addr = sk->sk_v6_daddr;
 438                 if (np->sndflow)
 439                         lsa->l2tp_flowinfo = np->flow_label;
 440         } else {
 441                 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
 442                         lsa->l2tp_addr = np->saddr;
 443                 else
 444                         lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
 445
 446                 lsa->l2tp_conn_id = lsk->conn_id;
 447         }
 448         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 449                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
 450         return sizeof(*lsa);
 451 }
 452
 453 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
 454 {
 455         int rc;
 456
 457         /* Charge it to the socket, dropping if the queue is full. */
 458         rc = sock_queue_rcv_skb(sk, skb);
 459         if (rc < 0)
 460                 goto drop;
 461
 462         return 0;
 463
 464 drop:
 465         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
 466         kfree_skb(skb);
 467         return -1;
 468 }
 469
 470 static int l2tp_ip6_push_pending_frames(struct sock *sk)
 471 {
 472         struct sk_buff *skb;
 473         __be32 *transhdr = NULL;
 474         int err = 0;
 475
 476         skb = skb_peek(&sk->sk_write_queue);
 477         if (skb == NULL)
 478                 goto out;
 479
 480         transhdr = (__be32 *)skb_transport_header(skb);
 481         *transhdr = 0;
 482
 483         err = ip6_push_pending_frames(sk);
 484
 485 out:
 486         return err;
 487 }
 488
 489 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
 490  * control frames.
 491  */
 492 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 493 {
 494         struct ipv6_txoptions opt_space;
 495         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 496         struct in6_addr *daddr, *final_p, final;
 497         struct ipv6_pinfo *np = inet6_sk(sk);
 498         struct ipv6_txoptions *opt_to_free = NULL;
 499         struct ipv6_txoptions *opt = NULL;
 500         struct ip6_flowlabel *flowlabel = NULL;
 501         struct dst_entry *dst = NULL;
 502         struct flowi6 fl6;
 503         struct sockcm_cookie sockc_unused = {0};
 504         struct ipcm6_cookie ipc6;
 505         int addr_len = msg->msg_namelen;
 506         int transhdrlen = 4; /* zero session-id */
 507         int ulen = len + transhdrlen;
 508         int err;
 509
 510         /* Rough check on arithmetic overflow,
 511            better check is made in ip6_append_data().
 512          */
 513         if (len > INT_MAX)
 514                 return -EMSGSIZE;
 515
 516         /* Mirror BSD error message compatibility */
 517         if (msg->msg_flags & MSG_OOB)
 518                 return -EOPNOTSUPP;
 519
 520         /*
 521          *      Get and verify the address.
 522          */
 523         memset(&fl6, 0, sizeof(fl6));
 524
 525         fl6.flowi6_mark = sk->sk_mark;
 526         fl6.flowi6_uid = sk->sk_uid;
 527
 528         ipc6.hlimit = -1;
 529         ipc6.tclass = -1;
 530         ipc6.dontfrag = -1;
 531
 532         if (lsa) {
 533                 if (addr_len < SIN6_LEN_RFC2133)
 534                         return -EINVAL;
 535
 536                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
 537                         return -EAFNOSUPPORT;
 538
 539                 daddr = &lsa->l2tp_addr;
 540                 if (np->sndflow) {
 541                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
 542                         if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
 543                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 544                                 if (flowlabel == NULL)
 545                                         return -EINVAL;
 546                         }
 547                 }
 548
 549                 /*
 550                  * Otherwise it will be difficult to maintain
 551                  * sk->sk_dst_cache.
 552                  */
 553                 if (sk->sk_state == TCP_ESTABLISHED &&
 554                     ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
 555                         daddr = &sk->sk_v6_daddr;
 556
 557                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 558                     lsa->l2tp_scope_id &&
 559                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
 560                         fl6.flowi6_oif = lsa->l2tp_scope_id;
 561         } else {
 562                 if (sk->sk_state != TCP_ESTABLISHED)
 563                         return -EDESTADDRREQ;
 564
 565                 daddr = &sk->sk_v6_daddr;
 566                 fl6.flowlabel = np->flow_label;
 567         }
 568
 569         if (fl6.flowi6_oif == 0)
 570                 fl6.flowi6_oif = sk->sk_bound_dev_if;
 571
 572         if (msg->msg_controllen) {
 573                 opt = &opt_space;
 574                 memset(opt, 0, sizeof(struct ipv6_txoptions));
 575                 opt->tot_len = sizeof(struct ipv6_txoptions);
 576                 ipc6.opt = opt;
 577
 578                 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6,
 579                                             &sockc_unused);
 580                 if (err < 0) {
 581                         fl6_sock_release(flowlabel);
 582                         return err;
 583                 }
 584                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
 585                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 586                         if (flowlabel == NULL)
 587                                 return -EINVAL;
 588                 }
 589                 if (!(opt->opt_nflen|opt->opt_flen))
 590                         opt = NULL;
 591         }
 592
 593         if (!opt) {
 594                 opt = txopt_get(np);
 595                 opt_to_free = opt;
 596         }
 597         if (flowlabel)
 598                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
 599         opt = ipv6_fixup_options(&opt_space, opt);
 600         ipc6.opt = opt;
 601
 602         fl6.flowi6_proto = sk->sk_protocol;
 603         if (!ipv6_addr_any(daddr))
 604                 fl6.daddr = *daddr;
 605         else
 606                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
 607         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
 608                 fl6.saddr = np->saddr;
 609
 610         final_p = fl6_update_dst(&fl6, opt, &final);
 611
 612         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 613                 fl6.flowi6_oif = np->mcast_oif;
 614         else if (!fl6.flowi6_oif)
 615                 fl6.flowi6_oif = np->ucast_oif;
 616
 617         security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 618
 619         if (ipc6.tclass < 0)
 620                 ipc6.tclass = np->tclass;
 621
 622         fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
 623
 624         dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
 625         if (IS_ERR(dst)) {
 626                 err = PTR_ERR(dst);
 627                 goto out;
 628         }
 629
 630         if (ipc6.hlimit < 0)
 631                 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
 632
 633         if (ipc6.dontfrag < 0)
 634                 ipc6.dontfrag = np->dontfrag;
 635
 636         if (msg->msg_flags & MSG_CONFIRM)
 637                 goto do_confirm;
 638
 639 back_from_confirm:
 640         lock_sock(sk);
 641         err = ip6_append_data(sk, ip_generic_getfrag, msg,
 642                               ulen, transhdrlen, &ipc6,
 643                               &fl6, (struct rt6_info *)dst,
 644                               msg->msg_flags, &sockc_unused);
 645         if (err)
 646                 ip6_flush_pending_frames(sk);
 647         else if (!(msg->msg_flags & MSG_MORE))
 648                 err = l2tp_ip6_push_pending_frames(sk);
 649         release_sock(sk);
 650 done:
 651         dst_release(dst);
 652 out:
 653         fl6_sock_release(flowlabel);
 654         txopt_put(opt_to_free);
 655
 656         return err < 0 ? err : len;
 657
 658 do_confirm:
 659         if (msg->msg_flags & MSG_PROBE)
 660                 dst_confirm_neigh(dst, &fl6.daddr);
 661         if (!(msg->msg_flags & MSG_PROBE) || len)
 662                 goto back_from_confirm;
 663         err = 0;
 664         goto done;
 665 }
 666
 667 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 668                             int noblock, int flags, int *addr_len)
 669 {
 670         struct ipv6_pinfo *np = inet6_sk(sk);
 671         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 672         size_t copied = 0;
 673         int err = -EOPNOTSUPP;
 674         struct sk_buff *skb;
 675
 676         if (flags & MSG_OOB)
 677                 goto out;
 678
 679         if (addr_len)
 680                 *addr_len = sizeof(*lsa);
 681
 682         if (flags & MSG_ERRQUEUE)
 683                 return ipv6_recv_error(sk, msg, len, addr_len);
 684
 685         skb = skb_recv_datagram(sk, flags, noblock, &err);
 686         if (!skb)
 687                 goto out;
 688
 689         copied = skb->len;
 690         if (len < copied) {
 691                 msg->msg_flags |= MSG_TRUNC;
 692                 copied = len;
 693         }
 694
 695         err = skb_copy_datagram_msg(skb, 0, msg, copied);
 696         if (err)
 697                 goto done;
 698
 699         sock_recv_timestamp(msg, sk, skb);
 700
 701         /* Copy the address. */
 702         if (lsa) {
 703                 lsa->l2tp_family = AF_INET6;
 704                 lsa->l2tp_unused = 0;
 705                 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
 706                 lsa->l2tp_flowinfo = 0;
 707                 lsa->l2tp_scope_id = 0;
 708                 lsa->l2tp_conn_id = 0;
 709                 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 710                         lsa->l2tp_scope_id = inet6_iif(skb);
 711         }
 712
 713         if (np->rxopt.all)
 714                 ip6_datagram_recv_ctl(sk, msg, skb);
 715
 716         if (flags & MSG_TRUNC)
 717                 copied = skb->len;
 718 done:
 719         skb_free_datagram(sk, skb);
 720 out:
 721         return err ? err : copied;
 722 }
 723
 724 static struct proto l2tp_ip6_prot = {
 725         .name              = "L2TP/IPv6",
 726         .owner             = THIS_MODULE,
 727         .init              = l2tp_ip6_open,
 728         .close             = l2tp_ip6_close,
 729         .bind              = l2tp_ip6_bind,
 730         .connect           = l2tp_ip6_connect,
 731         .disconnect        = l2tp_ip6_disconnect,
 732         .ioctl             = l2tp_ioctl,
 733         .destroy           = l2tp_ip6_destroy_sock,
 734         .setsockopt        = ipv6_setsockopt,
 735         .getsockopt        = ipv6_getsockopt,
 736         .sendmsg           = l2tp_ip6_sendmsg,
 737         .recvmsg           = l2tp_ip6_recvmsg,
 738         .backlog_rcv       = l2tp_ip6_backlog_recv,
 739         .hash              = inet6_hash,
 740         .unhash            = inet_unhash,
 741         .obj_size          = sizeof(struct l2tp_ip6_sock),
 742 #ifdef CONFIG_COMPAT
 743         .compat_setsockopt = compat_ipv6_setsockopt,
 744         .compat_getsockopt = compat_ipv6_getsockopt,
 745 #endif
 746 };
 747
 748 static const struct proto_ops l2tp_ip6_ops = {
 749         .family            = PF_INET6,
 750         .owner             = THIS_MODULE,
 751         .release           = inet6_release,
 752         .bind              = inet6_bind,
 753         .connect           = inet_dgram_connect,
 754         .socketpair        = sock_no_socketpair,
 755         .accept            = sock_no_accept,
 756         .getname           = l2tp_ip6_getname,
 757         .poll              = datagram_poll,
 758         .ioctl             = inet6_ioctl,
 759         .listen            = sock_no_listen,
 760         .shutdown          = inet_shutdown,
 761         .setsockopt        = sock_common_setsockopt,
 762         .getsockopt        = sock_common_getsockopt,
 763         .sendmsg           = inet_sendmsg,
 764         .recvmsg           = sock_common_recvmsg,
 765         .mmap              = sock_no_mmap,
 766         .sendpage          = sock_no_sendpage,
 767 #ifdef CONFIG_COMPAT
 768         .compat_setsockopt = compat_sock_common_setsockopt,
 769         .compat_getsockopt = compat_sock_common_getsockopt,
 770 #endif
 771 };
 772
 773 static struct inet_protosw l2tp_ip6_protosw = {
 774         .type           = SOCK_DGRAM,
 775         .protocol       = IPPROTO_L2TP,
 776         .prot           = &l2tp_ip6_prot,
 777         .ops            = &l2tp_ip6_ops,
 778 };
 779
 780 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
 781         .handler        = l2tp_ip6_recv,
 782 };
 783
 784 static int __init l2tp_ip6_init(void)
 785 {
 786         int err;
 787
 788         pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
 789
 790         err = proto_register(&l2tp_ip6_prot, 1);
 791         if (err != 0)
 792                 goto out;
 793
 794         err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 795         if (err)
 796                 goto out1;
 797
 798         inet6_register_protosw(&l2tp_ip6_protosw);
 799         return 0;
 800
 801 out1:
 802         proto_unregister(&l2tp_ip6_prot);
 803 out:
 804         return err;
 805 }
 806
 807 static void __exit l2tp_ip6_exit(void)
 808 {
 809         inet6_unregister_protosw(&l2tp_ip6_protosw);
 810         inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 811         proto_unregister(&l2tp_ip6_prot);
 812 }
 813
 814 module_init(l2tp_ip6_init);
 815 module_exit(l2tp_ip6_exit);
 816
 817 MODULE_LICENSE("GPL");
 818 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
 819 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
 820 MODULE_VERSION("1.0");
 821
 822 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 823  * enums
 824  */
 825 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
 826 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);