net/l2tp/l2tp_ip6.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * L2TPv3 IP encapsulation support for IPv6
   4  *
   5  * Copyright (c) 2012 Katalix Systems Ltd
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/icmp.h>
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/random.h>
  14 #include <linux/socket.h>
  15 #include <linux/l2tp.h>
  16 #include <linux/in.h>
  17 #include <linux/in6.h>
  18 #include <net/sock.h>
  19 #include <net/ip.h>
  20 #include <net/icmp.h>
  21 #include <net/udp.h>
  22 #include <net/inet_common.h>
  23 #include <net/inet_hashtables.h>
  24 #include <net/inet6_hashtables.h>
  25 #include <net/tcp_states.h>
  26 #include <net/protocol.h>
  27 #include <net/xfrm.h>
  28
  29 #include <net/transp_v6.h>
  30 #include <net/addrconf.h>
  31 #include <net/ip6_route.h>
  32
  33 #include "l2tp_core.h"
  34
  35 struct l2tp_ip6_sock {
  36         /* inet_sock has to be the first member of l2tp_ip6_sock */
  37         struct inet_sock        inet;
  38
  39         u32                     conn_id;
  40         u32                     peer_conn_id;
  41
  42         /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
  43            inet6_sk_generic */
  44         struct ipv6_pinfo       inet6;
  45 };
  46
  47 static DEFINE_RWLOCK(l2tp_ip6_lock);
  48 static struct hlist_head l2tp_ip6_table;
  49 static struct hlist_head l2tp_ip6_bind_table;
  50
  51 static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
  52 {
  53         return (struct l2tp_ip6_sock *)sk;
  54 }
  55
  56 static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
  57                                            const struct in6_addr *laddr,
  58                                            const struct in6_addr *raddr,
  59                                            int dif, u32 tunnel_id)
  60 {
  61         struct sock *sk;
  62
  63         sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
  64                 const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
  65                 const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
  66                 const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
  67
  68                 if (!net_eq(sock_net(sk), net))
  69                         continue;
  70
  71                 if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
  72                         continue;
  73
  74                 if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
  75                     !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
  76                         continue;
  77
  78                 if (!ipv6_addr_any(sk_raddr) && raddr &&
  79                     !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
  80                         continue;
  81
  82                 if (l2tp->conn_id != tunnel_id)
  83                         continue;
  84
  85                 goto found;
  86         }
  87
  88         sk = NULL;
  89 found:
  90         return sk;
  91 }
  92
  93 /* When processing receive frames, there are two cases to
  94  * consider. Data frames consist of a non-zero session-id and an
  95  * optional cookie. Control frames consist of a regular L2TP header
  96  * preceded by 32-bits of zeros.
  97  *
  98  * L2TPv3 Session Header Over IP
  99  *
 100  *  0                   1                   2                   3
 101  *  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
 102  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 103  * |                           Session ID                          |
 104  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 105  * |               Cookie (optional, maximum 64 bits)...
 106  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 107  *                                                                 |
 108  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 109  *
 110  * L2TPv3 Control Message Header Over IP
 111  *
 112  *  0                   1                   2                   3
 113  *  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
 114  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 115  * |                      (32 bits of zeros)                       |
 116  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 117  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
 118  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 119  * |                     Control Connection ID                     |
 120  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 121  * |               Ns              |               Nr              |
 122  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 123  *
 124  * All control frames are passed to userspace.
 125  */
 126 static int l2tp_ip6_recv(struct sk_buff *skb)
 127 {
 128         struct net *net = dev_net(skb->dev);
 129         struct sock *sk;
 130         u32 session_id;
 131         u32 tunnel_id;
 132         unsigned char *ptr, *optr;
 133         struct l2tp_session *session;
 134         struct l2tp_tunnel *tunnel = NULL;
 135         struct ipv6hdr *iph;
 136         int length;
 137
 138         if (!pskb_may_pull(skb, 4))
 139                 goto discard;
 140
 141         /* Point to L2TP header */
 142         optr = ptr = skb->data;
 143         session_id = ntohl(*((__be32 *) ptr));
 144         ptr += 4;
 145
 146         /* RFC3931: L2TP/IP packets have the first 4 bytes containing
 147          * the session_id. If it is 0, the packet is a L2TP control
 148          * frame and the session_id value can be discarded.
 149          */
 150         if (session_id == 0) {
 151                 __skb_pull(skb, 4);
 152                 goto pass_up;
 153         }
 154
 155         /* Ok, this is a data packet. Lookup the session. */
 156         session = l2tp_session_get(net, session_id);
 157         if (!session)
 158                 goto discard;
 159
 160         tunnel = session->tunnel;
 161         if (!tunnel)
 162                 goto discard_sess;
 163
 164         /* Trace packet contents, if enabled */
 165         if (tunnel->debug & L2TP_MSG_DATA) {
 166                 length = min(32u, skb->len);
 167                 if (!pskb_may_pull(skb, length))
 168                         goto discard_sess;
 169
 170                 /* Point to L2TP header */
 171                 optr = ptr = skb->data;
 172                 ptr += 4;
 173                 pr_debug("%s: ip recv\n", tunnel->name);
 174                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
 175         }
 176
 177         if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
 178                 goto discard_sess;
 179
 180         l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
 181         l2tp_session_dec_refcount(session);
 182
 183         return 0;
 184
 185 pass_up:
 186         /* Get the tunnel_id from the L2TP header */
 187         if (!pskb_may_pull(skb, 12))
 188                 goto discard;
 189
 190         if ((skb->data[0] & 0xc0) != 0xc0)
 191                 goto discard;
 192
 193         tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
 194         iph = ipv6_hdr(skb);
 195
 196         read_lock_bh(&l2tp_ip6_lock);
 197         sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
 198                                     inet6_iif(skb), tunnel_id);
 199         if (!sk) {
 200                 read_unlock_bh(&l2tp_ip6_lock);
 201                 goto discard;
 202         }
 203         sock_hold(sk);
 204         read_unlock_bh(&l2tp_ip6_lock);
 205
 206         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
 207                 goto discard_put;
 208
 209         nf_reset_ct(skb);
 210
 211         return sk_receive_skb(sk, skb, 1);
 212
 213 discard_sess:
 214         l2tp_session_dec_refcount(session);
 215         goto discard;
 216
 217 discard_put:
 218         sock_put(sk);
 219
 220 discard:
 221         kfree_skb(skb);
 222         return 0;
 223 }
 224
 225 static int l2tp_ip6_open(struct sock *sk)
 226 {
 227         /* Prevent autobind. We don't have ports. */
 228         inet_sk(sk)->inet_num = IPPROTO_L2TP;
 229
 230         write_lock_bh(&l2tp_ip6_lock);
 231         sk_add_node(sk, &l2tp_ip6_table);
 232         write_unlock_bh(&l2tp_ip6_lock);
 233
 234         return 0;
 235 }
 236
 237 static void l2tp_ip6_close(struct sock *sk, long timeout)
 238 {
 239         write_lock_bh(&l2tp_ip6_lock);
 240         hlist_del_init(&sk->sk_bind_node);
 241         sk_del_node_init(sk);
 242         write_unlock_bh(&l2tp_ip6_lock);
 243
 244         sk_common_release(sk);
 245 }
 246
 247 static void l2tp_ip6_destroy_sock(struct sock *sk)
 248 {
 249         struct l2tp_tunnel *tunnel = sk->sk_user_data;
 250
 251         lock_sock(sk);
 252         ip6_flush_pending_frames(sk);
 253         release_sock(sk);
 254
 255         if (tunnel)
 256                 l2tp_tunnel_delete(tunnel);
 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         struct net *net = sock_net(sk);
 267         __be32 v4addr = 0;
 268         int bound_dev_if;
 269         int addr_type;
 270         int err;
 271
 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         lock_sock(sk);
 288
 289         err = -EINVAL;
 290         if (!sock_flag(sk, SOCK_ZAPPED))
 291                 goto out_unlock;
 292
 293         if (sk->sk_state != TCP_CLOSE)
 294                 goto out_unlock;
 295
 296         bound_dev_if = sk->sk_bound_dev_if;
 297
 298         /* Check if the address belongs to the host. */
 299         rcu_read_lock();
 300         if (addr_type != IPV6_ADDR_ANY) {
 301                 struct net_device *dev = NULL;
 302
 303                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 304                         if (addr->l2tp_scope_id)
 305                                 bound_dev_if = addr->l2tp_scope_id;
 306
 307                         /* Binding to link-local address requires an
 308                          * interface.
 309                          */
 310                         if (!bound_dev_if)
 311                                 goto out_unlock_rcu;
 312
 313                         err = -ENODEV;
 314                         dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
 315                         if (!dev)
 316                                 goto out_unlock_rcu;
 317                 }
 318
 319                 /* ipv4 addr of the socket is invalid.  Only the
 320                  * unspecified and mapped address have a v4 equivalent.
 321                  */
 322                 v4addr = LOOPBACK4_IPV6;
 323                 err = -EADDRNOTAVAIL;
 324                 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
 325                         goto out_unlock_rcu;
 326         }
 327         rcu_read_unlock();
 328
 329         write_lock_bh(&l2tp_ip6_lock);
 330         if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
 331                                    addr->l2tp_conn_id)) {
 332                 write_unlock_bh(&l2tp_ip6_lock);
 333                 err = -EADDRINUSE;
 334                 goto out_unlock;
 335         }
 336
 337         inet->inet_saddr = v4addr;
 338         inet->inet_rcv_saddr = v4addr;
 339         sk->sk_bound_dev_if = bound_dev_if;
 340         sk->sk_v6_rcv_saddr = addr->l2tp_addr;
 341         np->saddr = addr->l2tp_addr;
 342
 343         l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
 344
 345         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 346         sk_del_node_init(sk);
 347         write_unlock_bh(&l2tp_ip6_lock);
 348
 349         sock_reset_flag(sk, SOCK_ZAPPED);
 350         release_sock(sk);
 351         return 0;
 352
 353 out_unlock_rcu:
 354         rcu_read_unlock();
 355 out_unlock:
 356         release_sock(sk);
 357
 358         return err;
 359 }
 360
 361 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
 362                             int addr_len)
 363 {
 364         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
 365         struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
 366         struct in6_addr *daddr;
 367         int     addr_type;
 368         int rc;
 369
 370         if (addr_len < sizeof(*lsa))
 371                 return -EINVAL;
 372
 373         if (usin->sin6_family != AF_INET6)
 374                 return -EINVAL;
 375
 376         addr_type = ipv6_addr_type(&usin->sin6_addr);
 377         if (addr_type & IPV6_ADDR_MULTICAST)
 378                 return -EINVAL;
 379
 380         if (addr_type & IPV6_ADDR_MAPPED) {
 381                 daddr = &usin->sin6_addr;
 382                 if (ipv4_is_multicast(daddr->s6_addr32[3]))
 383                         return -EINVAL;
 384         }
 385
 386         lock_sock(sk);
 387
 388          /* Must bind first - autobinding does not work */
 389         if (sock_flag(sk, SOCK_ZAPPED)) {
 390                 rc = -EINVAL;
 391                 goto out_sk;
 392         }
 393
 394         rc = __ip6_datagram_connect(sk, uaddr, addr_len);
 395         if (rc < 0)
 396                 goto out_sk;
 397
 398         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 399
 400         write_lock_bh(&l2tp_ip6_lock);
 401         hlist_del_init(&sk->sk_bind_node);
 402         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 403         write_unlock_bh(&l2tp_ip6_lock);
 404
 405 out_sk:
 406         release_sock(sk);
 407
 408         return rc;
 409 }
 410
 411 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
 412 {
 413         if (sock_flag(sk, SOCK_ZAPPED))
 414                 return 0;
 415
 416         return __udp_disconnect(sk, flags);
 417 }
 418
 419 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
 420                             int peer)
 421 {
 422         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
 423         struct sock *sk = sock->sk;
 424         struct ipv6_pinfo *np = inet6_sk(sk);
 425         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
 426
 427         lsa->l2tp_family = AF_INET6;
 428         lsa->l2tp_flowinfo = 0;
 429         lsa->l2tp_scope_id = 0;
 430         lsa->l2tp_unused = 0;
 431         if (peer) {
 432                 if (!lsk->peer_conn_id)
 433                         return -ENOTCONN;
 434                 lsa->l2tp_conn_id = lsk->peer_conn_id;
 435                 lsa->l2tp_addr = sk->sk_v6_daddr;
 436                 if (np->sndflow)
 437                         lsa->l2tp_flowinfo = np->flow_label;
 438         } else {
 439                 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
 440                         lsa->l2tp_addr = np->saddr;
 441                 else
 442                         lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
 443
 444                 lsa->l2tp_conn_id = lsk->conn_id;
 445         }
 446         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 447                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
 448         return sizeof(*lsa);
 449 }
 450
 451 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
 452 {
 453         int rc;
 454
 455         /* Charge it to the socket, dropping if the queue is full. */
 456         rc = sock_queue_rcv_skb(sk, skb);
 457         if (rc < 0)
 458                 goto drop;
 459
 460         return 0;
 461
 462 drop:
 463         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
 464         kfree_skb(skb);
 465         return -1;
 466 }
 467
 468 static int l2tp_ip6_push_pending_frames(struct sock *sk)
 469 {
 470         struct sk_buff *skb;
 471         __be32 *transhdr = NULL;
 472         int err = 0;
 473
 474         skb = skb_peek(&sk->sk_write_queue);
 475         if (skb == NULL)
 476                 goto out;
 477
 478         transhdr = (__be32 *)skb_transport_header(skb);
 479         *transhdr = 0;
 480
 481         err = ip6_push_pending_frames(sk);
 482
 483 out:
 484         return err;
 485 }
 486
 487 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
 488  * control frames.
 489  */
 490 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 491 {
 492         struct ipv6_txoptions opt_space;
 493         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 494         struct in6_addr *daddr, *final_p, final;
 495         struct ipv6_pinfo *np = inet6_sk(sk);
 496         struct ipv6_txoptions *opt_to_free = NULL;
 497         struct ipv6_txoptions *opt = NULL;
 498         struct ip6_flowlabel *flowlabel = NULL;
 499         struct dst_entry *dst = NULL;
 500         struct flowi6 fl6;
 501         struct ipcm6_cookie ipc6;
 502         int addr_len = msg->msg_namelen;
 503         int transhdrlen = 4; /* zero session-id */
 504         int ulen = len + transhdrlen;
 505         int err;
 506
 507         /* Rough check on arithmetic overflow,
 508            better check is made in ip6_append_data().
 509          */
 510         if (len > INT_MAX)
 511                 return -EMSGSIZE;
 512
 513         /* Mirror BSD error message compatibility */
 514         if (msg->msg_flags & MSG_OOB)
 515                 return -EOPNOTSUPP;
 516
 517         /*
 518          *      Get and verify the address.
 519          */
 520         memset(&fl6, 0, sizeof(fl6));
 521
 522         fl6.flowi6_mark = sk->sk_mark;
 523         fl6.flowi6_uid = sk->sk_uid;
 524
 525         ipcm6_init(&ipc6);
 526
 527         if (lsa) {
 528                 if (addr_len < SIN6_LEN_RFC2133)
 529                         return -EINVAL;
 530
 531                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
 532                         return -EAFNOSUPPORT;
 533
 534                 daddr = &lsa->l2tp_addr;
 535                 if (np->sndflow) {
 536                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
 537                         if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
 538                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 539                                 if (IS_ERR(flowlabel))
 540                                         return -EINVAL;
 541                         }
 542                 }
 543
 544                 /*
 545                  * Otherwise it will be difficult to maintain
 546                  * sk->sk_dst_cache.
 547                  */
 548                 if (sk->sk_state == TCP_ESTABLISHED &&
 549                     ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
 550                         daddr = &sk->sk_v6_daddr;
 551
 552                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 553                     lsa->l2tp_scope_id &&
 554                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
 555                         fl6.flowi6_oif = lsa->l2tp_scope_id;
 556         } else {
 557                 if (sk->sk_state != TCP_ESTABLISHED)
 558                         return -EDESTADDRREQ;
 559
 560                 daddr = &sk->sk_v6_daddr;
 561                 fl6.flowlabel = np->flow_label;
 562         }
 563
 564         if (fl6.flowi6_oif == 0)
 565                 fl6.flowi6_oif = sk->sk_bound_dev_if;
 566
 567         if (msg->msg_controllen) {
 568                 opt = &opt_space;
 569                 memset(opt, 0, sizeof(struct ipv6_txoptions));
 570                 opt->tot_len = sizeof(struct ipv6_txoptions);
 571                 ipc6.opt = opt;
 572
 573                 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
 574                 if (err < 0) {
 575                         fl6_sock_release(flowlabel);
 576                         return err;
 577                 }
 578                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
 579                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 580                         if (IS_ERR(flowlabel))
 581                                 return -EINVAL;
 582                 }
 583                 if (!(opt->opt_nflen|opt->opt_flen))
 584                         opt = NULL;
 585         }
 586
 587         if (!opt) {
 588                 opt = txopt_get(np);
 589                 opt_to_free = opt;
 590         }
 591         if (flowlabel)
 592                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
 593         opt = ipv6_fixup_options(&opt_space, opt);
 594         ipc6.opt = opt;
 595
 596         fl6.flowi6_proto = sk->sk_protocol;
 597         if (!ipv6_addr_any(daddr))
 598                 fl6.daddr = *daddr;
 599         else
 600                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
 601         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
 602                 fl6.saddr = np->saddr;
 603
 604         final_p = fl6_update_dst(&fl6, opt, &final);
 605
 606         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 607                 fl6.flowi6_oif = np->mcast_oif;
 608         else if (!fl6.flowi6_oif)
 609                 fl6.flowi6_oif = np->ucast_oif;
 610
 611         security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 612
 613         if (ipc6.tclass < 0)
 614                 ipc6.tclass = np->tclass;
 615
 616         fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
 617
 618         dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
 619         if (IS_ERR(dst)) {
 620                 err = PTR_ERR(dst);
 621                 goto out;
 622         }
 623
 624         if (ipc6.hlimit < 0)
 625                 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
 626
 627         if (ipc6.dontfrag < 0)
 628                 ipc6.dontfrag = np->dontfrag;
 629
 630         if (msg->msg_flags & MSG_CONFIRM)
 631                 goto do_confirm;
 632
 633 back_from_confirm:
 634         lock_sock(sk);
 635         err = ip6_append_data(sk, ip_generic_getfrag, msg,
 636                               ulen, transhdrlen, &ipc6,
 637                               &fl6, (struct rt6_info *)dst,
 638                               msg->msg_flags);
 639         if (err)
 640                 ip6_flush_pending_frames(sk);
 641         else if (!(msg->msg_flags & MSG_MORE))
 642                 err = l2tp_ip6_push_pending_frames(sk);
 643         release_sock(sk);
 644 done:
 645         dst_release(dst);
 646 out:
 647         fl6_sock_release(flowlabel);
 648         txopt_put(opt_to_free);
 649
 650         return err < 0 ? err : len;
 651
 652 do_confirm:
 653         if (msg->msg_flags & MSG_PROBE)
 654                 dst_confirm_neigh(dst, &fl6.daddr);
 655         if (!(msg->msg_flags & MSG_PROBE) || len)
 656                 goto back_from_confirm;
 657         err = 0;
 658         goto done;
 659 }
 660
 661 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 662                             int noblock, int flags, int *addr_len)
 663 {
 664         struct ipv6_pinfo *np = inet6_sk(sk);
 665         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 666         size_t copied = 0;
 667         int err = -EOPNOTSUPP;
 668         struct sk_buff *skb;
 669
 670         if (flags & MSG_OOB)
 671                 goto out;
 672
 673         if (flags & MSG_ERRQUEUE)
 674                 return ipv6_recv_error(sk, msg, len, addr_len);
 675
 676         skb = skb_recv_datagram(sk, flags, noblock, &err);
 677         if (!skb)
 678                 goto out;
 679
 680         copied = skb->len;
 681         if (len < copied) {
 682                 msg->msg_flags |= MSG_TRUNC;
 683                 copied = len;
 684         }
 685
 686         err = skb_copy_datagram_msg(skb, 0, msg, copied);
 687         if (err)
 688                 goto done;
 689
 690         sock_recv_timestamp(msg, sk, skb);
 691
 692         /* Copy the address. */
 693         if (lsa) {
 694                 lsa->l2tp_family = AF_INET6;
 695                 lsa->l2tp_unused = 0;
 696                 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
 697                 lsa->l2tp_flowinfo = 0;
 698                 lsa->l2tp_scope_id = 0;
 699                 lsa->l2tp_conn_id = 0;
 700                 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 701                         lsa->l2tp_scope_id = inet6_iif(skb);
 702                 *addr_len = sizeof(*lsa);
 703         }
 704
 705         if (np->rxopt.all)
 706                 ip6_datagram_recv_ctl(sk, msg, skb);
 707
 708         if (flags & MSG_TRUNC)
 709                 copied = skb->len;
 710 done:
 711         skb_free_datagram(sk, skb);
 712 out:
 713         return err ? err : copied;
 714 }
 715
 716 static struct proto l2tp_ip6_prot = {
 717         .name              = "L2TP/IPv6",
 718         .owner             = THIS_MODULE,
 719         .init              = l2tp_ip6_open,
 720         .close             = l2tp_ip6_close,
 721         .bind              = l2tp_ip6_bind,
 722         .connect           = l2tp_ip6_connect,
 723         .disconnect        = l2tp_ip6_disconnect,
 724         .ioctl             = l2tp_ioctl,
 725         .destroy           = l2tp_ip6_destroy_sock,
 726         .setsockopt        = ipv6_setsockopt,
 727         .getsockopt        = ipv6_getsockopt,
 728         .sendmsg           = l2tp_ip6_sendmsg,
 729         .recvmsg           = l2tp_ip6_recvmsg,
 730         .backlog_rcv       = l2tp_ip6_backlog_recv,
 731         .hash              = inet6_hash,
 732         .unhash            = inet_unhash,
 733         .obj_size          = sizeof(struct l2tp_ip6_sock),
 734 #ifdef CONFIG_COMPAT
 735         .compat_setsockopt = compat_ipv6_setsockopt,
 736         .compat_getsockopt = compat_ipv6_getsockopt,
 737 #endif
 738 };
 739
 740 static const struct proto_ops l2tp_ip6_ops = {
 741         .family            = PF_INET6,
 742         .owner             = THIS_MODULE,
 743         .release           = inet6_release,
 744         .bind              = inet6_bind,
 745         .connect           = inet_dgram_connect,
 746         .socketpair        = sock_no_socketpair,
 747         .accept            = sock_no_accept,
 748         .getname           = l2tp_ip6_getname,
 749         .poll              = datagram_poll,
 750         .ioctl             = inet6_ioctl,
 751         .gettstamp         = sock_gettstamp,
 752         .listen            = sock_no_listen,
 753         .shutdown          = inet_shutdown,
 754         .setsockopt        = sock_common_setsockopt,
 755         .getsockopt        = sock_common_getsockopt,
 756         .sendmsg           = inet_sendmsg,
 757         .recvmsg           = sock_common_recvmsg,
 758         .mmap              = sock_no_mmap,
 759         .sendpage          = sock_no_sendpage,
 760 #ifdef CONFIG_COMPAT
 761         .compat_setsockopt = compat_sock_common_setsockopt,
 762         .compat_getsockopt = compat_sock_common_getsockopt,
 763 #endif
 764 };
 765
 766 static struct inet_protosw l2tp_ip6_protosw = {
 767         .type           = SOCK_DGRAM,
 768         .protocol       = IPPROTO_L2TP,
 769         .prot           = &l2tp_ip6_prot,
 770         .ops            = &l2tp_ip6_ops,
 771 };
 772
 773 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
 774         .handler        = l2tp_ip6_recv,
 775 };
 776
 777 static int __init l2tp_ip6_init(void)
 778 {
 779         int err;
 780
 781         pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
 782
 783         err = proto_register(&l2tp_ip6_prot, 1);
 784         if (err != 0)
 785                 goto out;
 786
 787         err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 788         if (err)
 789                 goto out1;
 790
 791         inet6_register_protosw(&l2tp_ip6_protosw);
 792         return 0;
 793
 794 out1:
 795         proto_unregister(&l2tp_ip6_prot);
 796 out:
 797         return err;
 798 }
 799
 800 static void __exit l2tp_ip6_exit(void)
 801 {
 802         inet6_unregister_protosw(&l2tp_ip6_protosw);
 803         inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 804         proto_unregister(&l2tp_ip6_prot);
 805 }
 806
 807 module_init(l2tp_ip6_init);
 808 module_exit(l2tp_ip6_exit);
 809
 810 MODULE_LICENSE("GPL");
 811 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
 812 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
 813 MODULE_VERSION("1.0");
 814
 815 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 816  * enums
 817  */
 818 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
 819 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);