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 sock *sk;
  64
  65         sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
  66                 const struct in6_addr *addr = inet6_rcv_saddr(sk);
  67                 struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
  68
  69                 if (l2tp == NULL)
  70                         continue;
  71
  72                 if ((l2tp->conn_id == tunnel_id) &&
  73                     net_eq(sock_net(sk), net) &&
  74                     !(addr && ipv6_addr_equal(addr, laddr)) &&
  75                     !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif))
  76                         goto found;
  77         }
  78
  79         sk = NULL;
  80 found:
  81         return sk;
  82 }
  83
  84 static inline struct sock *l2tp_ip6_bind_lookup(struct net *net,
  85                                                 struct in6_addr *laddr,
  86                                                 int dif, u32 tunnel_id)
  87 {
  88         struct sock *sk = __l2tp_ip6_bind_lookup(net, laddr, dif, tunnel_id);
  89         if (sk)
  90                 sock_hold(sk);
  91
  92         return sk;
  93 }
  94
  95 /* When processing receive frames, there are two cases to
  96  * consider. Data frames consist of a non-zero session-id and an
  97  * optional cookie. Control frames consist of a regular L2TP header
  98  * preceded by 32-bits of zeros.
  99  *
 100  * L2TPv3 Session Header Over IP
 101  *
 102  *  0                   1                   2                   3
 103  *  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
 104  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 105  * |                           Session ID                          |
 106  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 107  * |               Cookie (optional, maximum 64 bits)...
 108  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 109  *                                                                 |
 110  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 111  *
 112  * L2TPv3 Control Message Header Over IP
 113  *
 114  *  0                   1                   2                   3
 115  *  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
 116  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 117  * |                      (32 bits of zeros)                       |
 118  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 119  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
 120  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 121  * |                     Control Connection ID                     |
 122  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 123  * |               Ns              |               Nr              |
 124  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 125  *
 126  * All control frames are passed to userspace.
 127  */
 128 static int l2tp_ip6_recv(struct sk_buff *skb)
 129 {
 130         struct sock *sk;
 131         u32 session_id;
 132         u32 tunnel_id;
 133         unsigned char *ptr, *optr;
 134         struct l2tp_session *session;
 135         struct l2tp_tunnel *tunnel = NULL;
 136         int length;
 137
 138         /* Point to L2TP header */
 139         optr = ptr = skb->data;
 140
 141         if (!pskb_may_pull(skb, 4))
 142                 goto discard;
 143
 144         session_id = ntohl(*((__be32 *) ptr));
 145         ptr += 4;
 146
 147         /* RFC3931: L2TP/IP packets have the first 4 bytes containing
 148          * the session_id. If it is 0, the packet is a L2TP control
 149          * frame and the session_id value can be discarded.
 150          */
 151         if (session_id == 0) {
 152                 __skb_pull(skb, 4);
 153                 goto pass_up;
 154         }
 155
 156         /* Ok, this is a data packet. Lookup the session. */
 157         session = l2tp_session_find(&init_net, NULL, session_id);
 158         if (session == NULL)
 159                 goto discard;
 160
 161         tunnel = session->tunnel;
 162         if (tunnel == NULL)
 163                 goto discard;
 164
 165         /* Trace packet contents, if enabled */
 166         if (tunnel->debug & L2TP_MSG_DATA) {
 167                 length = min(32u, skb->len);
 168                 if (!pskb_may_pull(skb, length))
 169                         goto discard;
 170
 171                 pr_debug("%s: ip recv\n", tunnel->name);
 172                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
 173         }
 174
 175         l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
 176                          tunnel->recv_payload_hook);
 177         return 0;
 178
 179 pass_up:
 180         /* Get the tunnel_id from the L2TP header */
 181         if (!pskb_may_pull(skb, 12))
 182                 goto discard;
 183
 184         if ((skb->data[0] & 0xc0) != 0xc0)
 185                 goto discard;
 186
 187         tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
 188         tunnel = l2tp_tunnel_find(&init_net, tunnel_id);
 189         if (tunnel != NULL)
 190                 sk = tunnel->sock;
 191         else {
 192                 struct ipv6hdr *iph = ipv6_hdr(skb);
 193
 194                 read_lock_bh(&l2tp_ip6_lock);
 195                 sk = __l2tp_ip6_bind_lookup(&init_net, &iph->daddr,
 196                                             0, tunnel_id);
 197                 read_unlock_bh(&l2tp_ip6_lock);
 198         }
 199
 200         if (sk == NULL)
 201                 goto discard;
 202
 203         sock_hold(sk);
 204
 205         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
 206                 goto discard_put;
 207
 208         nf_reset(skb);
 209
 210         return sk_receive_skb(sk, skb, 1);
 211
 212 discard_put:
 213         sock_put(sk);
 214
 215 discard:
 216         kfree_skb(skb);
 217         return 0;
 218 }
 219
 220 static int l2tp_ip6_open(struct sock *sk)
 221 {
 222         /* Prevent autobind. We don't have ports. */
 223         inet_sk(sk)->inet_num = IPPROTO_L2TP;
 224
 225         write_lock_bh(&l2tp_ip6_lock);
 226         sk_add_node(sk, &l2tp_ip6_table);
 227         write_unlock_bh(&l2tp_ip6_lock);
 228
 229         return 0;
 230 }
 231
 232 static void l2tp_ip6_close(struct sock *sk, long timeout)
 233 {
 234         write_lock_bh(&l2tp_ip6_lock);
 235         hlist_del_init(&sk->sk_bind_node);
 236         sk_del_node_init(sk);
 237         write_unlock_bh(&l2tp_ip6_lock);
 238
 239         sk_common_release(sk);
 240 }
 241
 242 static void l2tp_ip6_destroy_sock(struct sock *sk)
 243 {
 244         struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
 245
 246         lock_sock(sk);
 247         ip6_flush_pending_frames(sk);
 248         release_sock(sk);
 249
 250         if (tunnel) {
 251                 l2tp_tunnel_closeall(tunnel);
 252                 sock_put(sk);
 253         }
 254
 255         inet6_destroy_sock(sk);
 256 }
 257
 258 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 259 {
 260         struct inet_sock *inet = inet_sk(sk);
 261         struct ipv6_pinfo *np = inet6_sk(sk);
 262         struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
 263         __be32 v4addr = 0;
 264         int addr_type;
 265         int err;
 266
 267         if (!sock_flag(sk, SOCK_ZAPPED))
 268                 return -EINVAL;
 269         if (addr->l2tp_family != AF_INET6)
 270                 return -EINVAL;
 271         if (addr_len < sizeof(*addr))
 272                 return -EINVAL;
 273
 274         addr_type = ipv6_addr_type(&addr->l2tp_addr);
 275
 276         /* l2tp_ip6 sockets are IPv6 only */
 277         if (addr_type == IPV6_ADDR_MAPPED)
 278                 return -EADDRNOTAVAIL;
 279
 280         /* L2TP is point-point, not multicast */
 281         if (addr_type & IPV6_ADDR_MULTICAST)
 282                 return -EADDRNOTAVAIL;
 283
 284         err = -EADDRINUSE;
 285         read_lock_bh(&l2tp_ip6_lock);
 286         if (__l2tp_ip6_bind_lookup(&init_net, &addr->l2tp_addr,
 287                                    sk->sk_bound_dev_if, addr->l2tp_conn_id))
 288                 goto out_in_use;
 289         read_unlock_bh(&l2tp_ip6_lock);
 290
 291         lock_sock(sk);
 292
 293         err = -EINVAL;
 294         if (sk->sk_state != TCP_CLOSE)
 295                 goto out_unlock;
 296
 297         /* Check if the address belongs to the host. */
 298         rcu_read_lock();
 299         if (addr_type != IPV6_ADDR_ANY) {
 300                 struct net_device *dev = NULL;
 301
 302                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 303                         if (addr_len >= sizeof(struct sockaddr_in6) &&
 304                             addr->l2tp_scope_id) {
 305                                 /* Override any existing binding, if another
 306                                  * one is supplied by user.
 307                                  */
 308                                 sk->sk_bound_dev_if = addr->l2tp_scope_id;
 309                         }
 310
 311                         /* Binding to link-local address requires an
 312                            interface */
 313                         if (!sk->sk_bound_dev_if)
 314                                 goto out_unlock_rcu;
 315
 316                         err = -ENODEV;
 317                         dev = dev_get_by_index_rcu(sock_net(sk),
 318                                                    sk->sk_bound_dev_if);
 319                         if (!dev)
 320                                 goto out_unlock_rcu;
 321                 }
 322
 323                 /* ipv4 addr of the socket is invalid.  Only the
 324                  * unspecified and mapped address have a v4 equivalent.
 325                  */
 326                 v4addr = LOOPBACK4_IPV6;
 327                 err = -EADDRNOTAVAIL;
 328                 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
 329                         goto out_unlock_rcu;
 330         }
 331         rcu_read_unlock();
 332
 333         inet->inet_rcv_saddr = inet->inet_saddr = v4addr;
 334         sk->sk_v6_rcv_saddr = addr->l2tp_addr;
 335         np->saddr = addr->l2tp_addr;
 336
 337         l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
 338
 339         write_lock_bh(&l2tp_ip6_lock);
 340         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 341         sk_del_node_init(sk);
 342         write_unlock_bh(&l2tp_ip6_lock);
 343
 344         sock_reset_flag(sk, SOCK_ZAPPED);
 345         release_sock(sk);
 346         return 0;
 347
 348 out_unlock_rcu:
 349         rcu_read_unlock();
 350 out_unlock:
 351         release_sock(sk);
 352         return err;
 353
 354 out_in_use:
 355         read_unlock_bh(&l2tp_ip6_lock);
 356         return err;
 357 }
 358
 359 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
 360                             int addr_len)
 361 {
 362         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
 363         struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
 364         struct in6_addr *daddr;
 365         int     addr_type;
 366         int rc;
 367
 368         if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
 369                 return -EINVAL;
 370
 371         if (addr_len < sizeof(*lsa))
 372                 return -EINVAL;
 373
 374         if (usin->sin6_family != AF_INET6)
 375                 return -EINVAL;
 376
 377         addr_type = ipv6_addr_type(&usin->sin6_addr);
 378         if (addr_type & IPV6_ADDR_MULTICAST)
 379                 return -EINVAL;
 380
 381         if (addr_type & IPV6_ADDR_MAPPED) {
 382                 daddr = &usin->sin6_addr;
 383                 if (ipv4_is_multicast(daddr->s6_addr32[3]))
 384                         return -EINVAL;
 385         }
 386
 387         rc = ip6_datagram_connect(sk, uaddr, addr_len);
 388
 389         lock_sock(sk);
 390
 391         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 392
 393         write_lock_bh(&l2tp_ip6_lock);
 394         hlist_del_init(&sk->sk_bind_node);
 395         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 396         write_unlock_bh(&l2tp_ip6_lock);
 397
 398         release_sock(sk);
 399
 400         return rc;
 401 }
 402
 403 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
 404 {
 405         if (sock_flag(sk, SOCK_ZAPPED))
 406                 return 0;
 407
 408         return udp_disconnect(sk, flags);
 409 }
 410
 411 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
 412                             int *uaddr_len, int peer)
 413 {
 414         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
 415         struct sock *sk = sock->sk;
 416         struct ipv6_pinfo *np = inet6_sk(sk);
 417         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
 418
 419         lsa->l2tp_family = AF_INET6;
 420         lsa->l2tp_flowinfo = 0;
 421         lsa->l2tp_scope_id = 0;
 422         lsa->l2tp_unused = 0;
 423         if (peer) {
 424                 if (!lsk->peer_conn_id)
 425                         return -ENOTCONN;
 426                 lsa->l2tp_conn_id = lsk->peer_conn_id;
 427                 lsa->l2tp_addr = sk->sk_v6_daddr;
 428                 if (np->sndflow)
 429                         lsa->l2tp_flowinfo = np->flow_label;
 430         } else {
 431                 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
 432                         lsa->l2tp_addr = np->saddr;
 433                 else
 434                         lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
 435
 436                 lsa->l2tp_conn_id = lsk->conn_id;
 437         }
 438         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 439                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
 440         *uaddr_len = sizeof(*lsa);
 441         return 0;
 442 }
 443
 444 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
 445 {
 446         int rc;
 447
 448         /* Charge it to the socket, dropping if the queue is full. */
 449         rc = sock_queue_rcv_skb(sk, skb);
 450         if (rc < 0)
 451                 goto drop;
 452
 453         return 0;
 454
 455 drop:
 456         IP_INC_STATS(&init_net, IPSTATS_MIB_INDISCARDS);
 457         kfree_skb(skb);
 458         return -1;
 459 }
 460
 461 static int l2tp_ip6_push_pending_frames(struct sock *sk)
 462 {
 463         struct sk_buff *skb;
 464         __be32 *transhdr = NULL;
 465         int err = 0;
 466
 467         skb = skb_peek(&sk->sk_write_queue);
 468         if (skb == NULL)
 469                 goto out;
 470
 471         transhdr = (__be32 *)skb_transport_header(skb);
 472         *transhdr = 0;
 473
 474         err = ip6_push_pending_frames(sk);
 475
 476 out:
 477         return err;
 478 }
 479
 480 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
 481  * control frames.
 482  */
 483 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 484 {
 485         struct ipv6_txoptions opt_space;
 486         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 487         struct in6_addr *daddr, *final_p, final;
 488         struct ipv6_pinfo *np = inet6_sk(sk);
 489         struct ipv6_txoptions *opt_to_free = NULL;
 490         struct ipv6_txoptions *opt = NULL;
 491         struct ip6_flowlabel *flowlabel = NULL;
 492         struct dst_entry *dst = NULL;
 493         struct flowi6 fl6;
 494         int addr_len = msg->msg_namelen;
 495         int hlimit = -1;
 496         int tclass = -1;
 497         int dontfrag = -1;
 498         int transhdrlen = 4; /* zero session-id */
 499         int ulen = len + transhdrlen;
 500         int err;
 501
 502         /* Rough check on arithmetic overflow,
 503            better check is made in ip6_append_data().
 504          */
 505         if (len > INT_MAX)
 506                 return -EMSGSIZE;
 507
 508         /* Mirror BSD error message compatibility */
 509         if (msg->msg_flags & MSG_OOB)
 510                 return -EOPNOTSUPP;
 511
 512         /*
 513          *      Get and verify the address.
 514          */
 515         memset(&fl6, 0, sizeof(fl6));
 516
 517         fl6.flowi6_mark = sk->sk_mark;
 518
 519         if (lsa) {
 520                 if (addr_len < SIN6_LEN_RFC2133)
 521                         return -EINVAL;
 522
 523                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
 524                         return -EAFNOSUPPORT;
 525
 526                 daddr = &lsa->l2tp_addr;
 527                 if (np->sndflow) {
 528                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
 529                         if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
 530                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 531                                 if (flowlabel == NULL)
 532                                         return -EINVAL;
 533                         }
 534                 }
 535
 536                 /*
 537                  * Otherwise it will be difficult to maintain
 538                  * sk->sk_dst_cache.
 539                  */
 540                 if (sk->sk_state == TCP_ESTABLISHED &&
 541                     ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
 542                         daddr = &sk->sk_v6_daddr;
 543
 544                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 545                     lsa->l2tp_scope_id &&
 546                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
 547                         fl6.flowi6_oif = lsa->l2tp_scope_id;
 548         } else {
 549                 if (sk->sk_state != TCP_ESTABLISHED)
 550                         return -EDESTADDRREQ;
 551
 552                 daddr = &sk->sk_v6_daddr;
 553                 fl6.flowlabel = np->flow_label;
 554         }
 555
 556         if (fl6.flowi6_oif == 0)
 557                 fl6.flowi6_oif = sk->sk_bound_dev_if;
 558
 559         if (msg->msg_controllen) {
 560                 opt = &opt_space;
 561                 memset(opt, 0, sizeof(struct ipv6_txoptions));
 562                 opt->tot_len = sizeof(struct ipv6_txoptions);
 563
 564                 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, opt,
 565                                             &hlimit, &tclass, &dontfrag);
 566                 if (err < 0) {
 567                         fl6_sock_release(flowlabel);
 568                         return err;
 569                 }
 570                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
 571                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 572                         if (flowlabel == NULL)
 573                                 return -EINVAL;
 574                 }
 575                 if (!(opt->opt_nflen|opt->opt_flen))
 576                         opt = NULL;
 577         }
 578
 579         if (!opt) {
 580                 opt = txopt_get(np);
 581                 opt_to_free = opt;
 582         }
 583         if (flowlabel)
 584                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
 585         opt = ipv6_fixup_options(&opt_space, opt);
 586
 587         fl6.flowi6_proto = sk->sk_protocol;
 588         if (!ipv6_addr_any(daddr))
 589                 fl6.daddr = *daddr;
 590         else
 591                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
 592         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
 593                 fl6.saddr = np->saddr;
 594
 595         final_p = fl6_update_dst(&fl6, opt, &final);
 596
 597         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 598                 fl6.flowi6_oif = np->mcast_oif;
 599         else if (!fl6.flowi6_oif)
 600                 fl6.flowi6_oif = np->ucast_oif;
 601
 602         security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 603
 604         dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
 605         if (IS_ERR(dst)) {
 606                 err = PTR_ERR(dst);
 607                 goto out;
 608         }
 609
 610         if (hlimit < 0)
 611                 hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
 612
 613         if (tclass < 0)
 614                 tclass = np->tclass;
 615
 616         if (dontfrag < 0)
 617                 dontfrag = np->dontfrag;
 618
 619         if (msg->msg_flags & MSG_CONFIRM)
 620                 goto do_confirm;
 621
 622 back_from_confirm:
 623         lock_sock(sk);
 624         err = ip6_append_data(sk, ip_generic_getfrag, msg,
 625                               ulen, transhdrlen, hlimit, tclass, opt,
 626                               &fl6, (struct rt6_info *)dst,
 627                               msg->msg_flags, dontfrag);
 628         if (err)
 629                 ip6_flush_pending_frames(sk);
 630         else if (!(msg->msg_flags & MSG_MORE))
 631                 err = l2tp_ip6_push_pending_frames(sk);
 632         release_sock(sk);
 633 done:
 634         dst_release(dst);
 635 out:
 636         fl6_sock_release(flowlabel);
 637         txopt_put(opt_to_free);
 638
 639         return err < 0 ? err : len;
 640
 641 do_confirm:
 642         dst_confirm(dst);
 643         if (!(msg->msg_flags & MSG_PROBE) || len)
 644                 goto back_from_confirm;
 645         err = 0;
 646         goto done;
 647 }
 648
 649 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 650                             int noblock, int flags, int *addr_len)
 651 {
 652         struct ipv6_pinfo *np = inet6_sk(sk);
 653         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 654         size_t copied = 0;
 655         int err = -EOPNOTSUPP;
 656         struct sk_buff *skb;
 657
 658         if (flags & MSG_OOB)
 659                 goto out;
 660
 661         if (addr_len)
 662                 *addr_len = sizeof(*lsa);
 663
 664         if (flags & MSG_ERRQUEUE)
 665                 return ipv6_recv_error(sk, msg, len, addr_len);
 666
 667         skb = skb_recv_datagram(sk, flags, noblock, &err);
 668         if (!skb)
 669                 goto out;
 670
 671         copied = skb->len;
 672         if (len < copied) {
 673                 msg->msg_flags |= MSG_TRUNC;
 674                 copied = len;
 675         }
 676
 677         err = skb_copy_datagram_msg(skb, 0, msg, copied);
 678         if (err)
 679                 goto done;
 680
 681         sock_recv_timestamp(msg, sk, skb);
 682
 683         /* Copy the address. */
 684         if (lsa) {
 685                 lsa->l2tp_family = AF_INET6;
 686                 lsa->l2tp_unused = 0;
 687                 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
 688                 lsa->l2tp_flowinfo = 0;
 689                 lsa->l2tp_scope_id = 0;
 690                 lsa->l2tp_conn_id = 0;
 691                 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 692                         lsa->l2tp_scope_id = inet6_iif(skb);
 693         }
 694
 695         if (np->rxopt.all)
 696                 ip6_datagram_recv_ctl(sk, msg, skb);
 697
 698         if (flags & MSG_TRUNC)
 699                 copied = skb->len;
 700 done:
 701         skb_free_datagram(sk, skb);
 702 out:
 703         return err ? err : copied;
 704 }
 705
 706 static struct proto l2tp_ip6_prot = {
 707         .name              = "L2TP/IPv6",
 708         .owner             = THIS_MODULE,
 709         .init              = l2tp_ip6_open,
 710         .close             = l2tp_ip6_close,
 711         .bind              = l2tp_ip6_bind,
 712         .connect           = l2tp_ip6_connect,
 713         .disconnect        = l2tp_ip6_disconnect,
 714         .ioctl             = udp_ioctl,
 715         .destroy           = l2tp_ip6_destroy_sock,
 716         .setsockopt        = ipv6_setsockopt,
 717         .getsockopt        = ipv6_getsockopt,
 718         .sendmsg           = l2tp_ip6_sendmsg,
 719         .recvmsg           = l2tp_ip6_recvmsg,
 720         .backlog_rcv       = l2tp_ip6_backlog_recv,
 721         .hash              = inet_hash,
 722         .unhash            = inet_unhash,
 723         .obj_size          = sizeof(struct l2tp_ip6_sock),
 724 #ifdef CONFIG_COMPAT
 725         .compat_setsockopt = compat_ipv6_setsockopt,
 726         .compat_getsockopt = compat_ipv6_getsockopt,
 727 #endif
 728 };
 729
 730 static const struct proto_ops l2tp_ip6_ops = {
 731         .family            = PF_INET6,
 732         .owner             = THIS_MODULE,
 733         .release           = inet6_release,
 734         .bind              = inet6_bind,
 735         .connect           = inet_dgram_connect,
 736         .socketpair        = sock_no_socketpair,
 737         .accept            = sock_no_accept,
 738         .getname           = l2tp_ip6_getname,
 739         .poll              = datagram_poll,
 740         .ioctl             = inet6_ioctl,
 741         .listen            = sock_no_listen,
 742         .shutdown          = inet_shutdown,
 743         .setsockopt        = sock_common_setsockopt,
 744         .getsockopt        = sock_common_getsockopt,
 745         .sendmsg           = inet_sendmsg,
 746         .recvmsg           = sock_common_recvmsg,
 747         .mmap              = sock_no_mmap,
 748         .sendpage          = sock_no_sendpage,
 749 #ifdef CONFIG_COMPAT
 750         .compat_setsockopt = compat_sock_common_setsockopt,
 751         .compat_getsockopt = compat_sock_common_getsockopt,
 752 #endif
 753 };
 754
 755 static struct inet_protosw l2tp_ip6_protosw = {
 756         .type           = SOCK_DGRAM,
 757         .protocol       = IPPROTO_L2TP,
 758         .prot           = &l2tp_ip6_prot,
 759         .ops            = &l2tp_ip6_ops,
 760 };
 761
 762 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
 763         .handler        = l2tp_ip6_recv,
 764 };
 765
 766 static int __init l2tp_ip6_init(void)
 767 {
 768         int err;
 769
 770         pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
 771
 772         err = proto_register(&l2tp_ip6_prot, 1);
 773         if (err != 0)
 774                 goto out;
 775
 776         err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 777         if (err)
 778                 goto out1;
 779
 780         inet6_register_protosw(&l2tp_ip6_protosw);
 781         return 0;
 782
 783 out1:
 784         proto_unregister(&l2tp_ip6_prot);
 785 out:
 786         return err;
 787 }
 788
 789 static void __exit l2tp_ip6_exit(void)
 790 {
 791         inet6_unregister_protosw(&l2tp_ip6_protosw);
 792         inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 793         proto_unregister(&l2tp_ip6_prot);
 794 }
 795
 796 module_init(l2tp_ip6_init);
 797 module_exit(l2tp_ip6_exit);
 798
 799 MODULE_LICENSE("GPL");
 800 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
 801 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
 802 MODULE_VERSION("1.0");
 803
 804 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 805  * enums
 806  */
 807 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
 808 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);