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                 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         np->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         addr_type = ipv6_addr_type(&usin->sin6_addr);
 375         if (addr_type & IPV6_ADDR_MULTICAST)
 376                 return -EINVAL;
 377
 378         if (addr_type & IPV6_ADDR_MAPPED) {
 379                 daddr = &usin->sin6_addr;
 380                 if (ipv4_is_multicast(daddr->s6_addr32[3]))
 381                         return -EINVAL;
 382         }
 383
 384         rc = ip6_datagram_connect(sk, uaddr, addr_len);
 385
 386         lock_sock(sk);
 387
 388         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 389
 390         write_lock_bh(&l2tp_ip6_lock);
 391         hlist_del_init(&sk->sk_bind_node);
 392         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 393         write_unlock_bh(&l2tp_ip6_lock);
 394
 395         release_sock(sk);
 396
 397         return rc;
 398 }
 399
 400 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
 401 {
 402         if (sock_flag(sk, SOCK_ZAPPED))
 403                 return 0;
 404
 405         return udp_disconnect(sk, flags);
 406 }
 407
 408 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
 409                             int *uaddr_len, int peer)
 410 {
 411         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
 412         struct sock *sk = sock->sk;
 413         struct ipv6_pinfo *np = inet6_sk(sk);
 414         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
 415
 416         lsa->l2tp_family = AF_INET6;
 417         lsa->l2tp_flowinfo = 0;
 418         lsa->l2tp_scope_id = 0;
 419         lsa->l2tp_unused = 0;
 420         if (peer) {
 421                 if (!lsk->peer_conn_id)
 422                         return -ENOTCONN;
 423                 lsa->l2tp_conn_id = lsk->peer_conn_id;
 424                 lsa->l2tp_addr = np->daddr;
 425                 if (np->sndflow)
 426                         lsa->l2tp_flowinfo = np->flow_label;
 427         } else {
 428                 if (ipv6_addr_any(&np->rcv_saddr))
 429                         lsa->l2tp_addr = np->saddr;
 430                 else
 431                         lsa->l2tp_addr = np->rcv_saddr;
 432
 433                 lsa->l2tp_conn_id = lsk->conn_id;
 434         }
 435         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 436                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
 437         *uaddr_len = sizeof(*lsa);
 438         return 0;
 439 }
 440
 441 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
 442 {
 443         int rc;
 444
 445         /* Charge it to the socket, dropping if the queue is full. */
 446         rc = sock_queue_rcv_skb(sk, skb);
 447         if (rc < 0)
 448                 goto drop;
 449
 450         return 0;
 451
 452 drop:
 453         IP_INC_STATS(&init_net, IPSTATS_MIB_INDISCARDS);
 454         kfree_skb(skb);
 455         return -1;
 456 }
 457
 458 static int l2tp_ip6_push_pending_frames(struct sock *sk)
 459 {
 460         struct sk_buff *skb;
 461         __be32 *transhdr = NULL;
 462         int err = 0;
 463
 464         skb = skb_peek(&sk->sk_write_queue);
 465         if (skb == NULL)
 466                 goto out;
 467
 468         transhdr = (__be32 *)skb_transport_header(skb);
 469         *transhdr = 0;
 470
 471         err = ip6_push_pending_frames(sk);
 472
 473 out:
 474         return err;
 475 }
 476
 477 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
 478  * control frames.
 479  */
 480 static int l2tp_ip6_sendmsg(struct kiocb *iocb, struct sock *sk,
 481                             struct msghdr *msg, size_t len)
 482 {
 483         struct ipv6_txoptions opt_space;
 484         struct sockaddr_l2tpip6 *lsa =
 485                 (struct sockaddr_l2tpip6 *) msg->msg_name;
 486         struct in6_addr *daddr, *final_p, final;
 487         struct ipv6_pinfo *np = inet6_sk(sk);
 488         struct ipv6_txoptions *opt = NULL;
 489         struct ip6_flowlabel *flowlabel = NULL;
 490         struct dst_entry *dst = NULL;
 491         struct flowi6 fl6;
 492         int addr_len = msg->msg_namelen;
 493         int hlimit = -1;
 494         int tclass = -1;
 495         int dontfrag = -1;
 496         int transhdrlen = 4; /* zero session-id */
 497         int ulen = len + transhdrlen;
 498         int err;
 499
 500         /* Rough check on arithmetic overflow,
 501            better check is made in ip6_append_data().
 502          */
 503         if (len > INT_MAX)
 504                 return -EMSGSIZE;
 505
 506         /* Mirror BSD error message compatibility */
 507         if (msg->msg_flags & MSG_OOB)
 508                 return -EOPNOTSUPP;
 509
 510         /*
 511          *      Get and verify the address.
 512          */
 513         memset(&fl6, 0, sizeof(fl6));
 514
 515         fl6.flowi6_mark = sk->sk_mark;
 516
 517         if (lsa) {
 518                 if (addr_len < SIN6_LEN_RFC2133)
 519                         return -EINVAL;
 520
 521                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
 522                         return -EAFNOSUPPORT;
 523
 524                 daddr = &lsa->l2tp_addr;
 525                 if (np->sndflow) {
 526                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
 527                         if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
 528                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 529                                 if (flowlabel == NULL)
 530                                         return -EINVAL;
 531                                 daddr = &flowlabel->dst;
 532                         }
 533                 }
 534
 535                 /*
 536                  * Otherwise it will be difficult to maintain
 537                  * sk->sk_dst_cache.
 538                  */
 539                 if (sk->sk_state == TCP_ESTABLISHED &&
 540                     ipv6_addr_equal(daddr, &np->daddr))
 541                         daddr = &np->daddr;
 542
 543                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 544                     lsa->l2tp_scope_id &&
 545                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
 546                         fl6.flowi6_oif = lsa->l2tp_scope_id;
 547         } else {
 548                 if (sk->sk_state != TCP_ESTABLISHED)
 549                         return -EDESTADDRREQ;
 550
 551                 daddr = &np->daddr;
 552                 fl6.flowlabel = np->flow_label;
 553         }
 554
 555         if (fl6.flowi6_oif == 0)
 556                 fl6.flowi6_oif = sk->sk_bound_dev_if;
 557
 558         if (msg->msg_controllen) {
 559                 opt = &opt_space;
 560                 memset(opt, 0, sizeof(struct ipv6_txoptions));
 561                 opt->tot_len = sizeof(struct ipv6_txoptions);
 562
 563                 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, opt,
 564                                             &hlimit, &tclass, &dontfrag);
 565                 if (err < 0) {
 566                         fl6_sock_release(flowlabel);
 567                         return err;
 568                 }
 569                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
 570                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 571                         if (flowlabel == NULL)
 572                                 return -EINVAL;
 573                 }
 574                 if (!(opt->opt_nflen|opt->opt_flen))
 575                         opt = NULL;
 576         }
 577
 578         if (opt == NULL)
 579                 opt = np->opt;
 580         if (flowlabel)
 581                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
 582         opt = ipv6_fixup_options(&opt_space, opt);
 583
 584         fl6.flowi6_proto = sk->sk_protocol;
 585         if (!ipv6_addr_any(daddr))
 586                 fl6.daddr = *daddr;
 587         else
 588                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
 589         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
 590                 fl6.saddr = np->saddr;
 591
 592         final_p = fl6_update_dst(&fl6, opt, &final);
 593
 594         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 595                 fl6.flowi6_oif = np->mcast_oif;
 596         else if (!fl6.flowi6_oif)
 597                 fl6.flowi6_oif = np->ucast_oif;
 598
 599         security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 600
 601         dst = ip6_dst_lookup_flow(sk, &fl6, final_p, true);
 602         if (IS_ERR(dst)) {
 603                 err = PTR_ERR(dst);
 604                 goto out;
 605         }
 606
 607         if (hlimit < 0) {
 608                 if (ipv6_addr_is_multicast(&fl6.daddr))
 609                         hlimit = np->mcast_hops;
 610                 else
 611                         hlimit = np->hop_limit;
 612                 if (hlimit < 0)
 613                         hlimit = ip6_dst_hoplimit(dst);
 614         }
 615
 616         if (tclass < 0)
 617                 tclass = np->tclass;
 618
 619         if (dontfrag < 0)
 620                 dontfrag = np->dontfrag;
 621
 622         if (msg->msg_flags & MSG_CONFIRM)
 623                 goto do_confirm;
 624
 625 back_from_confirm:
 626         lock_sock(sk);
 627         err = ip6_append_data(sk, ip_generic_getfrag, msg->msg_iov,
 628                               ulen, transhdrlen, hlimit, tclass, opt,
 629                               &fl6, (struct rt6_info *)dst,
 630                               msg->msg_flags, dontfrag);
 631         if (err)
 632                 ip6_flush_pending_frames(sk);
 633         else if (!(msg->msg_flags & MSG_MORE))
 634                 err = l2tp_ip6_push_pending_frames(sk);
 635         release_sock(sk);
 636 done:
 637         dst_release(dst);
 638 out:
 639         fl6_sock_release(flowlabel);
 640
 641         return err < 0 ? err : len;
 642
 643 do_confirm:
 644         dst_confirm(dst);
 645         if (!(msg->msg_flags & MSG_PROBE) || len)
 646                 goto back_from_confirm;
 647         err = 0;
 648         goto done;
 649 }
 650
 651 static int l2tp_ip6_recvmsg(struct kiocb *iocb, struct sock *sk,
 652                             struct msghdr *msg, size_t len, int noblock,
 653                             int flags, int *addr_len)
 654 {
 655         struct ipv6_pinfo *np = inet6_sk(sk);
 656         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)msg->msg_name;
 657         size_t copied = 0;
 658         int err = -EOPNOTSUPP;
 659         struct sk_buff *skb;
 660
 661         if (flags & MSG_OOB)
 662                 goto out;
 663
 664         if (addr_len)
 665                 *addr_len = sizeof(*lsa);
 666
 667         if (flags & MSG_ERRQUEUE)
 668                 return ipv6_recv_error(sk, msg, len, addr_len);
 669
 670         skb = skb_recv_datagram(sk, flags, noblock, &err);
 671         if (!skb)
 672                 goto out;
 673
 674         copied = skb->len;
 675         if (len < copied) {
 676                 msg->msg_flags |= MSG_TRUNC;
 677                 copied = len;
 678         }
 679
 680         err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
 681         if (err)
 682                 goto done;
 683
 684         sock_recv_timestamp(msg, sk, skb);
 685
 686         /* Copy the address. */
 687         if (lsa) {
 688                 lsa->l2tp_family = AF_INET6;
 689                 lsa->l2tp_unused = 0;
 690                 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
 691                 lsa->l2tp_flowinfo = 0;
 692                 lsa->l2tp_scope_id = 0;
 693                 lsa->l2tp_conn_id = 0;
 694                 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 695                         lsa->l2tp_scope_id = IP6CB(skb)->iif;
 696         }
 697
 698         if (np->rxopt.all)
 699                 ip6_datagram_recv_ctl(sk, msg, skb);
 700
 701         if (flags & MSG_TRUNC)
 702                 copied = skb->len;
 703 done:
 704         skb_free_datagram(sk, skb);
 705 out:
 706         return err ? err : copied;
 707 }
 708
 709 static struct proto l2tp_ip6_prot = {
 710         .name              = "L2TP/IPv6",
 711         .owner             = THIS_MODULE,
 712         .init              = l2tp_ip6_open,
 713         .close             = l2tp_ip6_close,
 714         .bind              = l2tp_ip6_bind,
 715         .connect           = l2tp_ip6_connect,
 716         .disconnect        = l2tp_ip6_disconnect,
 717         .ioctl             = udp_ioctl,
 718         .destroy           = l2tp_ip6_destroy_sock,
 719         .setsockopt        = ipv6_setsockopt,
 720         .getsockopt        = ipv6_getsockopt,
 721         .sendmsg           = l2tp_ip6_sendmsg,
 722         .recvmsg           = l2tp_ip6_recvmsg,
 723         .backlog_rcv       = l2tp_ip6_backlog_recv,
 724         .hash              = inet_hash,
 725         .unhash            = inet_unhash,
 726         .obj_size          = sizeof(struct l2tp_ip6_sock),
 727 #ifdef CONFIG_COMPAT
 728         .compat_setsockopt = compat_ipv6_setsockopt,
 729         .compat_getsockopt = compat_ipv6_getsockopt,
 730 #endif
 731 };
 732
 733 static const struct proto_ops l2tp_ip6_ops = {
 734         .family            = PF_INET6,
 735         .owner             = THIS_MODULE,
 736         .release           = inet6_release,
 737         .bind              = inet6_bind,
 738         .connect           = inet_dgram_connect,
 739         .socketpair        = sock_no_socketpair,
 740         .accept            = sock_no_accept,
 741         .getname           = l2tp_ip6_getname,
 742         .poll              = datagram_poll,
 743         .ioctl             = inet6_ioctl,
 744         .listen            = sock_no_listen,
 745         .shutdown          = inet_shutdown,
 746         .setsockopt        = sock_common_setsockopt,
 747         .getsockopt        = sock_common_getsockopt,
 748         .sendmsg           = inet_sendmsg,
 749         .recvmsg           = sock_common_recvmsg,
 750         .mmap              = sock_no_mmap,
 751         .sendpage          = sock_no_sendpage,
 752 #ifdef CONFIG_COMPAT
 753         .compat_setsockopt = compat_sock_common_setsockopt,
 754         .compat_getsockopt = compat_sock_common_getsockopt,
 755 #endif
 756 };
 757
 758 static struct inet_protosw l2tp_ip6_protosw = {
 759         .type           = SOCK_DGRAM,
 760         .protocol       = IPPROTO_L2TP,
 761         .prot           = &l2tp_ip6_prot,
 762         .ops            = &l2tp_ip6_ops,
 763         .no_check       = 0,
 764 };
 765
 766 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
 767         .handler        = l2tp_ip6_recv,
 768 };
 769
 770 static int __init l2tp_ip6_init(void)
 771 {
 772         int err;
 773
 774         pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
 775
 776         err = proto_register(&l2tp_ip6_prot, 1);
 777         if (err != 0)
 778                 goto out;
 779
 780         err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 781         if (err)
 782                 goto out1;
 783
 784         inet6_register_protosw(&l2tp_ip6_protosw);
 785         return 0;
 786
 787 out1:
 788         proto_unregister(&l2tp_ip6_prot);
 789 out:
 790         return err;
 791 }
 792
 793 static void __exit l2tp_ip6_exit(void)
 794 {
 795         inet6_unregister_protosw(&l2tp_ip6_protosw);
 796         inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 797         proto_unregister(&l2tp_ip6_prot);
 798 }
 799
 800 module_init(l2tp_ip6_init);
 801 module_exit(l2tp_ip6_exit);
 802
 803 MODULE_LICENSE("GPL");
 804 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
 805 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
 806 MODULE_VERSION("1.0");
 807
 808 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 809  * enums
 810  */
 811 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);