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(struct net *net,
  61                                            struct in6_addr *laddr,
  62                                            int dif, u32 tunnel_id)
  63 {
  64         struct sock *sk;
  65
  66         sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
  67                 const 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         if (!pskb_may_pull(skb, 4))
 140                 goto discard;
 141
 142         /* Point to L2TP header */
 143         optr = ptr = skb->data;
 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                 /* Point to L2TP header */
 172                 optr = ptr = skb->data;
 173                 ptr += 4;
 174                 pr_debug("%s: ip recv\n", tunnel->name);
 175                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
 176         }
 177
 178         l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
 179                          tunnel->recv_payload_hook);
 180         return 0;
 181
 182 pass_up:
 183         /* Get the tunnel_id from the L2TP header */
 184         if (!pskb_may_pull(skb, 12))
 185                 goto discard;
 186
 187         if ((skb->data[0] & 0xc0) != 0xc0)
 188                 goto discard;
 189
 190         tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
 191         tunnel = l2tp_tunnel_find(&init_net, tunnel_id);
 192         if (tunnel != NULL)
 193                 sk = tunnel->sock;
 194         else {
 195                 struct ipv6hdr *iph = ipv6_hdr(skb);
 196
 197                 read_lock_bh(&l2tp_ip6_lock);
 198                 sk = __l2tp_ip6_bind_lookup(&init_net, &iph->daddr,
 199                                             0, tunnel_id);
 200                 read_unlock_bh(&l2tp_ip6_lock);
 201         }
 202
 203         if (sk == NULL)
 204                 goto discard;
 205
 206         sock_hold(sk);
 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_put:
 216         sock_put(sk);
 217
 218 discard:
 219         kfree_skb(skb);
 220         return 0;
 221 }
 222
 223 static int l2tp_ip6_open(struct sock *sk)
 224 {
 225         /* Prevent autobind. We don't have ports. */
 226         inet_sk(sk)->inet_num = IPPROTO_L2TP;
 227
 228         write_lock_bh(&l2tp_ip6_lock);
 229         sk_add_node(sk, &l2tp_ip6_table);
 230         write_unlock_bh(&l2tp_ip6_lock);
 231
 232         return 0;
 233 }
 234
 235 static void l2tp_ip6_close(struct sock *sk, long timeout)
 236 {
 237         write_lock_bh(&l2tp_ip6_lock);
 238         hlist_del_init(&sk->sk_bind_node);
 239         sk_del_node_init(sk);
 240         write_unlock_bh(&l2tp_ip6_lock);
 241
 242         sk_common_release(sk);
 243 }
 244
 245 static void l2tp_ip6_destroy_sock(struct sock *sk)
 246 {
 247         struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
 248
 249         lock_sock(sk);
 250         ip6_flush_pending_frames(sk);
 251         release_sock(sk);
 252
 253         if (tunnel) {
 254                 l2tp_tunnel_closeall(tunnel);
 255                 sock_put(sk);
 256         }
 257
 258         inet6_destroy_sock(sk);
 259 }
 260
 261 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 262 {
 263         struct inet_sock *inet = inet_sk(sk);
 264         struct ipv6_pinfo *np = inet6_sk(sk);
 265         struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
 266         __be32 v4addr = 0;
 267         int addr_type;
 268         int err;
 269
 270         if (!sock_flag(sk, SOCK_ZAPPED))
 271                 return -EINVAL;
 272         if (addr->l2tp_family != AF_INET6)
 273                 return -EINVAL;
 274         if (addr_len < sizeof(*addr))
 275                 return -EINVAL;
 276
 277         addr_type = ipv6_addr_type(&addr->l2tp_addr);
 278
 279         /* l2tp_ip6 sockets are IPv6 only */
 280         if (addr_type == IPV6_ADDR_MAPPED)
 281                 return -EADDRNOTAVAIL;
 282
 283         /* L2TP is point-point, not multicast */
 284         if (addr_type & IPV6_ADDR_MULTICAST)
 285                 return -EADDRNOTAVAIL;
 286
 287         err = -EADDRINUSE;
 288         read_lock_bh(&l2tp_ip6_lock);
 289         if (__l2tp_ip6_bind_lookup(&init_net, &addr->l2tp_addr,
 290                                    sk->sk_bound_dev_if, addr->l2tp_conn_id))
 291                 goto out_in_use;
 292         read_unlock_bh(&l2tp_ip6_lock);
 293
 294         lock_sock(sk);
 295
 296         err = -EINVAL;
 297         if (sk->sk_state != TCP_CLOSE)
 298                 goto out_unlock;
 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_len >= sizeof(struct sockaddr_in6) &&
 307                             addr->l2tp_scope_id) {
 308                                 /* Override any existing binding, if another
 309                                  * one is supplied by user.
 310                                  */
 311                                 sk->sk_bound_dev_if = addr->l2tp_scope_id;
 312                         }
 313
 314                         /* Binding to link-local address requires an
 315                            interface */
 316                         if (!sk->sk_bound_dev_if)
 317                                 goto out_unlock_rcu;
 318
 319                         err = -ENODEV;
 320                         dev = dev_get_by_index_rcu(sock_net(sk),
 321                                                    sk->sk_bound_dev_if);
 322                         if (!dev)
 323                                 goto out_unlock_rcu;
 324                 }
 325
 326                 /* ipv4 addr of the socket is invalid.  Only the
 327                  * unspecified and mapped address have a v4 equivalent.
 328                  */
 329                 v4addr = LOOPBACK4_IPV6;
 330                 err = -EADDRNOTAVAIL;
 331                 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
 332                         goto out_unlock_rcu;
 333         }
 334         rcu_read_unlock();
 335
 336         inet->inet_rcv_saddr = inet->inet_saddr = v4addr;
 337         sk->sk_v6_rcv_saddr = addr->l2tp_addr;
 338         np->saddr = addr->l2tp_addr;
 339
 340         l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
 341
 342         write_lock_bh(&l2tp_ip6_lock);
 343         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 344         sk_del_node_init(sk);
 345         write_unlock_bh(&l2tp_ip6_lock);
 346
 347         sock_reset_flag(sk, SOCK_ZAPPED);
 348         release_sock(sk);
 349         return 0;
 350
 351 out_unlock_rcu:
 352         rcu_read_unlock();
 353 out_unlock:
 354         release_sock(sk);
 355         return err;
 356
 357 out_in_use:
 358         read_unlock_bh(&l2tp_ip6_lock);
 359         return err;
 360 }
 361
 362 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
 363                             int addr_len)
 364 {
 365         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
 366         struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
 367         struct in6_addr *daddr;
 368         int     addr_type;
 369         int rc;
 370
 371         if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
 372                 return -EINVAL;
 373
 374         if (addr_len < sizeof(*lsa))
 375                 return -EINVAL;
 376
 377         if (usin->sin6_family != AF_INET6)
 378                 return -EINVAL;
 379
 380         addr_type = ipv6_addr_type(&usin->sin6_addr);
 381         if (addr_type & IPV6_ADDR_MULTICAST)
 382                 return -EINVAL;
 383
 384         if (addr_type & IPV6_ADDR_MAPPED) {
 385                 daddr = &usin->sin6_addr;
 386                 if (ipv4_is_multicast(daddr->s6_addr32[3]))
 387                         return -EINVAL;
 388         }
 389
 390         rc = ip6_datagram_connect(sk, uaddr, addr_len);
 391
 392         lock_sock(sk);
 393
 394         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 395
 396         write_lock_bh(&l2tp_ip6_lock);
 397         hlist_del_init(&sk->sk_bind_node);
 398         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 399         write_unlock_bh(&l2tp_ip6_lock);
 400
 401         release_sock(sk);
 402
 403         return rc;
 404 }
 405
 406 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
 407 {
 408         if (sock_flag(sk, SOCK_ZAPPED))
 409                 return 0;
 410
 411         return udp_disconnect(sk, flags);
 412 }
 413
 414 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
 415                             int *uaddr_len, int peer)
 416 {
 417         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
 418         struct sock *sk = sock->sk;
 419         struct ipv6_pinfo *np = inet6_sk(sk);
 420         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
 421
 422         lsa->l2tp_family = AF_INET6;
 423         lsa->l2tp_flowinfo = 0;
 424         lsa->l2tp_scope_id = 0;
 425         lsa->l2tp_unused = 0;
 426         if (peer) {
 427                 if (!lsk->peer_conn_id)
 428                         return -ENOTCONN;
 429                 lsa->l2tp_conn_id = lsk->peer_conn_id;
 430                 lsa->l2tp_addr = sk->sk_v6_daddr;
 431                 if (np->sndflow)
 432                         lsa->l2tp_flowinfo = np->flow_label;
 433         } else {
 434                 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
 435                         lsa->l2tp_addr = np->saddr;
 436                 else
 437                         lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
 438
 439                 lsa->l2tp_conn_id = lsk->conn_id;
 440         }
 441         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 442                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
 443         *uaddr_len = sizeof(*lsa);
 444         return 0;
 445 }
 446
 447 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
 448 {
 449         int rc;
 450
 451         /* Charge it to the socket, dropping if the queue is full. */
 452         rc = sock_queue_rcv_skb(sk, skb);
 453         if (rc < 0)
 454                 goto drop;
 455
 456         return 0;
 457
 458 drop:
 459         IP_INC_STATS(&init_net, IPSTATS_MIB_INDISCARDS);
 460         kfree_skb(skb);
 461         return -1;
 462 }
 463
 464 static int l2tp_ip6_push_pending_frames(struct sock *sk)
 465 {
 466         struct sk_buff *skb;
 467         __be32 *transhdr = NULL;
 468         int err = 0;
 469
 470         skb = skb_peek(&sk->sk_write_queue);
 471         if (skb == NULL)
 472                 goto out;
 473
 474         transhdr = (__be32 *)skb_transport_header(skb);
 475         *transhdr = 0;
 476
 477         err = ip6_push_pending_frames(sk);
 478
 479 out:
 480         return err;
 481 }
 482
 483 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
 484  * control frames.
 485  */
 486 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 487 {
 488         struct ipv6_txoptions opt_space;
 489         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 490         struct in6_addr *daddr, *final_p, final;
 491         struct ipv6_pinfo *np = inet6_sk(sk);
 492         struct ipv6_txoptions *opt_to_free = NULL;
 493         struct ipv6_txoptions *opt = NULL;
 494         struct ip6_flowlabel *flowlabel = NULL;
 495         struct dst_entry *dst = NULL;
 496         struct flowi6 fl6;
 497         int addr_len = msg->msg_namelen;
 498         int hlimit = -1;
 499         int tclass = -1;
 500         int dontfrag = -1;
 501         int transhdrlen = 4; /* zero session-id */
 502         int ulen = len + transhdrlen;
 503         int err;
 504
 505         /* Rough check on arithmetic overflow,
 506            better check is made in ip6_append_data().
 507          */
 508         if (len > INT_MAX)
 509                 return -EMSGSIZE;
 510
 511         /* Mirror BSD error message compatibility */
 512         if (msg->msg_flags & MSG_OOB)
 513                 return -EOPNOTSUPP;
 514
 515         /*
 516          *      Get and verify the address.
 517          */
 518         memset(&fl6, 0, sizeof(fl6));
 519
 520         fl6.flowi6_mark = sk->sk_mark;
 521
 522         if (lsa) {
 523                 if (addr_len < SIN6_LEN_RFC2133)
 524                         return -EINVAL;
 525
 526                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
 527                         return -EAFNOSUPPORT;
 528
 529                 daddr = &lsa->l2tp_addr;
 530                 if (np->sndflow) {
 531                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
 532                         if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
 533                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 534                                 if (flowlabel == NULL)
 535                                         return -EINVAL;
 536                         }
 537                 }
 538
 539                 /*
 540                  * Otherwise it will be difficult to maintain
 541                  * sk->sk_dst_cache.
 542                  */
 543                 if (sk->sk_state == TCP_ESTABLISHED &&
 544                     ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
 545                         daddr = &sk->sk_v6_daddr;
 546
 547                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 548                     lsa->l2tp_scope_id &&
 549                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
 550                         fl6.flowi6_oif = lsa->l2tp_scope_id;
 551         } else {
 552                 if (sk->sk_state != TCP_ESTABLISHED)
 553                         return -EDESTADDRREQ;
 554
 555                 daddr = &sk->sk_v6_daddr;
 556                 fl6.flowlabel = np->flow_label;
 557         }
 558
 559         if (fl6.flowi6_oif == 0)
 560                 fl6.flowi6_oif = sk->sk_bound_dev_if;
 561
 562         if (msg->msg_controllen) {
 563                 opt = &opt_space;
 564                 memset(opt, 0, sizeof(struct ipv6_txoptions));
 565                 opt->tot_len = sizeof(struct ipv6_txoptions);
 566
 567                 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, opt,
 568                                             &hlimit, &tclass, &dontfrag);
 569                 if (err < 0) {
 570                         fl6_sock_release(flowlabel);
 571                         return err;
 572                 }
 573                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
 574                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 575                         if (flowlabel == NULL)
 576                                 return -EINVAL;
 577                 }
 578                 if (!(opt->opt_nflen|opt->opt_flen))
 579                         opt = NULL;
 580         }
 581
 582         if (!opt) {
 583                 opt = txopt_get(np);
 584                 opt_to_free = opt;
 585         }
 586         if (flowlabel)
 587                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
 588         opt = ipv6_fixup_options(&opt_space, opt);
 589
 590         fl6.flowi6_proto = sk->sk_protocol;
 591         if (!ipv6_addr_any(daddr))
 592                 fl6.daddr = *daddr;
 593         else
 594                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
 595         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
 596                 fl6.saddr = np->saddr;
 597
 598         final_p = fl6_update_dst(&fl6, opt, &final);
 599
 600         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 601                 fl6.flowi6_oif = np->mcast_oif;
 602         else if (!fl6.flowi6_oif)
 603                 fl6.flowi6_oif = np->ucast_oif;
 604
 605         security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 606
 607         dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
 608         if (IS_ERR(dst)) {
 609                 err = PTR_ERR(dst);
 610                 goto out;
 611         }
 612
 613         if (hlimit < 0)
 614                 hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
 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,
 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         txopt_put(opt_to_free);
 641
 642         return err < 0 ? err : len;
 643
 644 do_confirm:
 645         dst_confirm(dst);
 646         if (!(msg->msg_flags & MSG_PROBE) || len)
 647                 goto back_from_confirm;
 648         err = 0;
 649         goto done;
 650 }
 651
 652 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 653                             int noblock, int flags, int *addr_len)
 654 {
 655         struct ipv6_pinfo *np = inet6_sk(sk);
 656         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, 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_msg(skb, 0, msg, 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 = inet6_iif(skb);
 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              = inet6_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 };
 764
 765 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
 766         .handler        = l2tp_ip6_recv,
 767 };
 768
 769 static int __init l2tp_ip6_init(void)
 770 {
 771         int err;
 772
 773         pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
 774
 775         err = proto_register(&l2tp_ip6_prot, 1);
 776         if (err != 0)
 777                 goto out;
 778
 779         err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 780         if (err)
 781                 goto out1;
 782
 783         inet6_register_protosw(&l2tp_ip6_protosw);
 784         return 0;
 785
 786 out1:
 787         proto_unregister(&l2tp_ip6_prot);
 788 out:
 789         return err;
 790 }
 791
 792 static void __exit l2tp_ip6_exit(void)
 793 {
 794         inet6_unregister_protosw(&l2tp_ip6_protosw);
 795         inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 796         proto_unregister(&l2tp_ip6_prot);
 797 }
 798
 799 module_init(l2tp_ip6_init);
 800 module_exit(l2tp_ip6_exit);
 801
 802 MODULE_LICENSE("GPL");
 803 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
 804 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
 805 MODULE_VERSION("1.0");
 806
 807 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 808  * enums
 809  */
 810 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
 811 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);