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                                            const struct in6_addr *raddr,
  63                                            int dif, u32 tunnel_id)
  64 {
  65         struct sock *sk;
  66
  67         sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
  68                 const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
  69                 const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
  70                 struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
  71
  72                 if (l2tp == NULL)
  73                         continue;
  74
  75                 if ((l2tp->conn_id == tunnel_id) &&
  76                     net_eq(sock_net(sk), net) &&
  77                     (!sk_laddr || ipv6_addr_any(sk_laddr) || ipv6_addr_equal(sk_laddr, laddr)) &&
  78                     (!raddr || ipv6_addr_any(sk_raddr) || ipv6_addr_equal(sk_raddr, raddr)) &&
  79                     (!sk->sk_bound_dev_if || !dif ||
  80                      sk->sk_bound_dev_if == dif))
  81                         goto found;
  82         }
  83
  84         sk = NULL;
  85 found:
  86         return sk;
  87 }
  88
  89 /* When processing receive frames, there are two cases to
  90  * consider. Data frames consist of a non-zero session-id and an
  91  * optional cookie. Control frames consist of a regular L2TP header
  92  * preceded by 32-bits of zeros.
  93  *
  94  * L2TPv3 Session Header Over IP
  95  *
  96  *  0                   1                   2                   3
  97  *  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
  98  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  99  * |                           Session ID                          |
 100  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 101  * |               Cookie (optional, maximum 64 bits)...
 102  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 103  *                                                                 |
 104  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 105  *
 106  * L2TPv3 Control Message Header Over IP
 107  *
 108  *  0                   1                   2                   3
 109  *  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
 110  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 111  * |                      (32 bits of zeros)                       |
 112  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 113  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
 114  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 115  * |                     Control Connection ID                     |
 116  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 117  * |               Ns              |               Nr              |
 118  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 119  *
 120  * All control frames are passed to userspace.
 121  */
 122 static int l2tp_ip6_recv(struct sk_buff *skb)
 123 {
 124         struct net *net = dev_net(skb->dev);
 125         struct sock *sk;
 126         u32 session_id;
 127         u32 tunnel_id;
 128         unsigned char *ptr, *optr;
 129         struct l2tp_session *session;
 130         struct l2tp_tunnel *tunnel = NULL;
 131         int length;
 132
 133         if (!pskb_may_pull(skb, 4))
 134                 goto discard;
 135
 136         /* Point to L2TP header */
 137         optr = ptr = skb->data;
 138         session_id = ntohl(*((__be32 *) ptr));
 139         ptr += 4;
 140
 141         /* RFC3931: L2TP/IP packets have the first 4 bytes containing
 142          * the session_id. If it is 0, the packet is a L2TP control
 143          * frame and the session_id value can be discarded.
 144          */
 145         if (session_id == 0) {
 146                 __skb_pull(skb, 4);
 147                 goto pass_up;
 148         }
 149
 150         /* Ok, this is a data packet. Lookup the session. */
 151         session = l2tp_session_get(net, NULL, session_id, true);
 152         if (!session)
 153                 goto discard;
 154
 155         tunnel = session->tunnel;
 156         if (!tunnel)
 157                 goto discard_sess;
 158
 159         /* Trace packet contents, if enabled */
 160         if (tunnel->debug & L2TP_MSG_DATA) {
 161                 length = min(32u, skb->len);
 162                 if (!pskb_may_pull(skb, length))
 163                         goto discard_sess;
 164
 165                 /* Point to L2TP header */
 166                 optr = ptr = skb->data;
 167                 ptr += 4;
 168                 pr_debug("%s: ip recv\n", tunnel->name);
 169                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
 170         }
 171
 172         l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
 173                          tunnel->recv_payload_hook);
 174         l2tp_session_dec_refcount(session);
 175
 176         return 0;
 177
 178 pass_up:
 179         /* Get the tunnel_id from the L2TP header */
 180         if (!pskb_may_pull(skb, 12))
 181                 goto discard;
 182
 183         if ((skb->data[0] & 0xc0) != 0xc0)
 184                 goto discard;
 185
 186         tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
 187         tunnel = l2tp_tunnel_find(net, tunnel_id);
 188         if (tunnel) {
 189                 sk = tunnel->sock;
 190                 sock_hold(sk);
 191         } else {
 192                 struct ipv6hdr *iph = ipv6_hdr(skb);
 193
 194                 read_lock_bh(&l2tp_ip6_lock);
 195                 sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
 196                                             inet6_iif(skb), tunnel_id);
 197                 if (!sk) {
 198                         read_unlock_bh(&l2tp_ip6_lock);
 199                         goto discard;
 200                 }
 201
 202                 sock_hold(sk);
 203                 read_unlock_bh(&l2tp_ip6_lock);
 204         }
 205
 206         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
 207                 goto discard_put;
 208
 209         nf_reset(skb);
 210
 211         return sk_receive_skb(sk, skb, 1);
 212
 213 discard_sess:
 214         if (session->deref)
 215                 session->deref(session);
 216         l2tp_session_dec_refcount(session);
 217         goto discard;
 218
 219 discard_put:
 220         sock_put(sk);
 221
 222 discard:
 223         kfree_skb(skb);
 224         return 0;
 225 }
 226
 227 static int l2tp_ip6_open(struct sock *sk)
 228 {
 229         /* Prevent autobind. We don't have ports. */
 230         inet_sk(sk)->inet_num = IPPROTO_L2TP;
 231
 232         write_lock_bh(&l2tp_ip6_lock);
 233         sk_add_node(sk, &l2tp_ip6_table);
 234         write_unlock_bh(&l2tp_ip6_lock);
 235
 236         return 0;
 237 }
 238
 239 static void l2tp_ip6_close(struct sock *sk, long timeout)
 240 {
 241         write_lock_bh(&l2tp_ip6_lock);
 242         hlist_del_init(&sk->sk_bind_node);
 243         sk_del_node_init(sk);
 244         write_unlock_bh(&l2tp_ip6_lock);
 245
 246         sk_common_release(sk);
 247 }
 248
 249 static void l2tp_ip6_destroy_sock(struct sock *sk)
 250 {
 251         struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
 252
 253         lock_sock(sk);
 254         ip6_flush_pending_frames(sk);
 255         release_sock(sk);
 256
 257         if (tunnel) {
 258                 l2tp_tunnel_closeall(tunnel);
 259                 sock_put(sk);
 260         }
 261
 262         inet6_destroy_sock(sk);
 263 }
 264
 265 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 266 {
 267         struct inet_sock *inet = inet_sk(sk);
 268         struct ipv6_pinfo *np = inet6_sk(sk);
 269         struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
 270         struct net *net = sock_net(sk);
 271         __be32 v4addr = 0;
 272         int bound_dev_if;
 273         int addr_type;
 274         int err;
 275
 276         if (addr->l2tp_family != AF_INET6)
 277                 return -EINVAL;
 278         if (addr_len < sizeof(*addr))
 279                 return -EINVAL;
 280
 281         addr_type = ipv6_addr_type(&addr->l2tp_addr);
 282
 283         /* l2tp_ip6 sockets are IPv6 only */
 284         if (addr_type == IPV6_ADDR_MAPPED)
 285                 return -EADDRNOTAVAIL;
 286
 287         /* L2TP is point-point, not multicast */
 288         if (addr_type & IPV6_ADDR_MULTICAST)
 289                 return -EADDRNOTAVAIL;
 290
 291         lock_sock(sk);
 292
 293         err = -EINVAL;
 294         if (!sock_flag(sk, SOCK_ZAPPED))
 295                 goto out_unlock;
 296
 297         if (sk->sk_state != TCP_CLOSE)
 298                 goto out_unlock;
 299
 300         bound_dev_if = sk->sk_bound_dev_if;
 301
 302         /* Check if the address belongs to the host. */
 303         rcu_read_lock();
 304         if (addr_type != IPV6_ADDR_ANY) {
 305                 struct net_device *dev = NULL;
 306
 307                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 308                         if (addr->l2tp_scope_id)
 309                                 bound_dev_if = addr->l2tp_scope_id;
 310
 311                         /* Binding to link-local address requires an
 312                          * interface.
 313                          */
 314                         if (!bound_dev_if)
 315                                 goto out_unlock_rcu;
 316
 317                         err = -ENODEV;
 318                         dev = dev_get_by_index_rcu(sock_net(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         write_lock_bh(&l2tp_ip6_lock);
 334         if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
 335                                    addr->l2tp_conn_id)) {
 336                 write_unlock_bh(&l2tp_ip6_lock);
 337                 err = -EADDRINUSE;
 338                 goto out_unlock;
 339         }
 340
 341         inet->inet_saddr = v4addr;
 342         inet->inet_rcv_saddr = v4addr;
 343         sk->sk_bound_dev_if = bound_dev_if;
 344         sk->sk_v6_rcv_saddr = addr->l2tp_addr;
 345         np->saddr = addr->l2tp_addr;
 346
 347         l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
 348
 349         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 350         sk_del_node_init(sk);
 351         write_unlock_bh(&l2tp_ip6_lock);
 352
 353         sock_reset_flag(sk, SOCK_ZAPPED);
 354         release_sock(sk);
 355         return 0;
 356
 357 out_unlock_rcu:
 358         rcu_read_unlock();
 359 out_unlock:
 360         release_sock(sk);
 361
 362         return err;
 363 }
 364
 365 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
 366                             int addr_len)
 367 {
 368         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
 369         struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
 370         struct in6_addr *daddr;
 371         int     addr_type;
 372         int rc;
 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         lock_sock(sk);
 391
 392          /* Must bind first - autobinding does not work */
 393         if (sock_flag(sk, SOCK_ZAPPED)) {
 394                 rc = -EINVAL;
 395                 goto out_sk;
 396         }
 397
 398         rc = __ip6_datagram_connect(sk, uaddr, addr_len);
 399         if (rc < 0)
 400                 goto out_sk;
 401
 402         l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 403
 404         write_lock_bh(&l2tp_ip6_lock);
 405         hlist_del_init(&sk->sk_bind_node);
 406         sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 407         write_unlock_bh(&l2tp_ip6_lock);
 408
 409 out_sk:
 410         release_sock(sk);
 411
 412         return rc;
 413 }
 414
 415 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
 416 {
 417         if (sock_flag(sk, SOCK_ZAPPED))
 418                 return 0;
 419
 420         return __udp_disconnect(sk, flags);
 421 }
 422
 423 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
 424                             int *uaddr_len, int peer)
 425 {
 426         struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
 427         struct sock *sk = sock->sk;
 428         struct ipv6_pinfo *np = inet6_sk(sk);
 429         struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
 430
 431         lsa->l2tp_family = AF_INET6;
 432         lsa->l2tp_flowinfo = 0;
 433         lsa->l2tp_scope_id = 0;
 434         lsa->l2tp_unused = 0;
 435         if (peer) {
 436                 if (!lsk->peer_conn_id)
 437                         return -ENOTCONN;
 438                 lsa->l2tp_conn_id = lsk->peer_conn_id;
 439                 lsa->l2tp_addr = sk->sk_v6_daddr;
 440                 if (np->sndflow)
 441                         lsa->l2tp_flowinfo = np->flow_label;
 442         } else {
 443                 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
 444                         lsa->l2tp_addr = np->saddr;
 445                 else
 446                         lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
 447
 448                 lsa->l2tp_conn_id = lsk->conn_id;
 449         }
 450         if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 451                 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
 452         *uaddr_len = sizeof(*lsa);
 453         return 0;
 454 }
 455
 456 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
 457 {
 458         int rc;
 459
 460         /* Charge it to the socket, dropping if the queue is full. */
 461         rc = sock_queue_rcv_skb(sk, skb);
 462         if (rc < 0)
 463                 goto drop;
 464
 465         return 0;
 466
 467 drop:
 468         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
 469         kfree_skb(skb);
 470         return -1;
 471 }
 472
 473 static int l2tp_ip6_push_pending_frames(struct sock *sk)
 474 {
 475         struct sk_buff *skb;
 476         __be32 *transhdr = NULL;
 477         int err = 0;
 478
 479         skb = skb_peek(&sk->sk_write_queue);
 480         if (skb == NULL)
 481                 goto out;
 482
 483         transhdr = (__be32 *)skb_transport_header(skb);
 484         *transhdr = 0;
 485
 486         err = ip6_push_pending_frames(sk);
 487
 488 out:
 489         return err;
 490 }
 491
 492 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
 493  * control frames.
 494  */
 495 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 496 {
 497         struct ipv6_txoptions opt_space;
 498         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 499         struct in6_addr *daddr, *final_p, final;
 500         struct ipv6_pinfo *np = inet6_sk(sk);
 501         struct ipv6_txoptions *opt_to_free = NULL;
 502         struct ipv6_txoptions *opt = NULL;
 503         struct ip6_flowlabel *flowlabel = NULL;
 504         struct dst_entry *dst = NULL;
 505         struct flowi6 fl6;
 506         struct sockcm_cookie sockc_unused = {0};
 507         struct ipcm6_cookie ipc6;
 508         int addr_len = msg->msg_namelen;
 509         int transhdrlen = 4; /* zero session-id */
 510         int ulen = len + transhdrlen;
 511         int err;
 512
 513         /* Rough check on arithmetic overflow,
 514            better check is made in ip6_append_data().
 515          */
 516         if (len > INT_MAX)
 517                 return -EMSGSIZE;
 518
 519         /* Mirror BSD error message compatibility */
 520         if (msg->msg_flags & MSG_OOB)
 521                 return -EOPNOTSUPP;
 522
 523         /*
 524          *      Get and verify the address.
 525          */
 526         memset(&fl6, 0, sizeof(fl6));
 527
 528         fl6.flowi6_mark = sk->sk_mark;
 529
 530         ipc6.hlimit = -1;
 531         ipc6.tclass = -1;
 532         ipc6.dontfrag = -1;
 533
 534         if (lsa) {
 535                 if (addr_len < SIN6_LEN_RFC2133)
 536                         return -EINVAL;
 537
 538                 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
 539                         return -EAFNOSUPPORT;
 540
 541                 daddr = &lsa->l2tp_addr;
 542                 if (np->sndflow) {
 543                         fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
 544                         if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
 545                                 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 546                                 if (flowlabel == NULL)
 547                                         return -EINVAL;
 548                         }
 549                 }
 550
 551                 /*
 552                  * Otherwise it will be difficult to maintain
 553                  * sk->sk_dst_cache.
 554                  */
 555                 if (sk->sk_state == TCP_ESTABLISHED &&
 556                     ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
 557                         daddr = &sk->sk_v6_daddr;
 558
 559                 if (addr_len >= sizeof(struct sockaddr_in6) &&
 560                     lsa->l2tp_scope_id &&
 561                     ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
 562                         fl6.flowi6_oif = lsa->l2tp_scope_id;
 563         } else {
 564                 if (sk->sk_state != TCP_ESTABLISHED)
 565                         return -EDESTADDRREQ;
 566
 567                 daddr = &sk->sk_v6_daddr;
 568                 fl6.flowlabel = np->flow_label;
 569         }
 570
 571         if (fl6.flowi6_oif == 0)
 572                 fl6.flowi6_oif = sk->sk_bound_dev_if;
 573
 574         if (msg->msg_controllen) {
 575                 opt = &opt_space;
 576                 memset(opt, 0, sizeof(struct ipv6_txoptions));
 577                 opt->tot_len = sizeof(struct ipv6_txoptions);
 578                 ipc6.opt = opt;
 579
 580                 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6,
 581                                             &sockc_unused);
 582                 if (err < 0) {
 583                         fl6_sock_release(flowlabel);
 584                         return err;
 585                 }
 586                 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
 587                         flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 588                         if (flowlabel == NULL)
 589                                 return -EINVAL;
 590                 }
 591                 if (!(opt->opt_nflen|opt->opt_flen))
 592                         opt = NULL;
 593         }
 594
 595         if (!opt) {
 596                 opt = txopt_get(np);
 597                 opt_to_free = opt;
 598         }
 599         if (flowlabel)
 600                 opt = fl6_merge_options(&opt_space, flowlabel, opt);
 601         opt = ipv6_fixup_options(&opt_space, opt);
 602         ipc6.opt = opt;
 603
 604         fl6.flowi6_proto = sk->sk_protocol;
 605         if (!ipv6_addr_any(daddr))
 606                 fl6.daddr = *daddr;
 607         else
 608                 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
 609         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
 610                 fl6.saddr = np->saddr;
 611
 612         final_p = fl6_update_dst(&fl6, opt, &final);
 613
 614         if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 615                 fl6.flowi6_oif = np->mcast_oif;
 616         else if (!fl6.flowi6_oif)
 617                 fl6.flowi6_oif = np->ucast_oif;
 618
 619         security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 620
 621         if (ipc6.tclass < 0)
 622                 ipc6.tclass = np->tclass;
 623
 624         fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
 625
 626         dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
 627         if (IS_ERR(dst)) {
 628                 err = PTR_ERR(dst);
 629                 goto out;
 630         }
 631
 632         if (ipc6.hlimit < 0)
 633                 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
 634
 635         if (ipc6.dontfrag < 0)
 636                 ipc6.dontfrag = np->dontfrag;
 637
 638         if (msg->msg_flags & MSG_CONFIRM)
 639                 goto do_confirm;
 640
 641 back_from_confirm:
 642         lock_sock(sk);
 643         err = ip6_append_data(sk, ip_generic_getfrag, msg,
 644                               ulen, transhdrlen, &ipc6,
 645                               &fl6, (struct rt6_info *)dst,
 646                               msg->msg_flags, &sockc_unused);
 647         if (err)
 648                 ip6_flush_pending_frames(sk);
 649         else if (!(msg->msg_flags & MSG_MORE))
 650                 err = l2tp_ip6_push_pending_frames(sk);
 651         release_sock(sk);
 652 done:
 653         dst_release(dst);
 654 out:
 655         fl6_sock_release(flowlabel);
 656         txopt_put(opt_to_free);
 657
 658         return err < 0 ? err : len;
 659
 660 do_confirm:
 661         dst_confirm(dst);
 662         if (!(msg->msg_flags & MSG_PROBE) || len)
 663                 goto back_from_confirm;
 664         err = 0;
 665         goto done;
 666 }
 667
 668 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 669                             int noblock, int flags, int *addr_len)
 670 {
 671         struct ipv6_pinfo *np = inet6_sk(sk);
 672         DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 673         size_t copied = 0;
 674         int err = -EOPNOTSUPP;
 675         struct sk_buff *skb;
 676
 677         if (flags & MSG_OOB)
 678                 goto out;
 679
 680         if (addr_len)
 681                 *addr_len = sizeof(*lsa);
 682
 683         if (flags & MSG_ERRQUEUE)
 684                 return ipv6_recv_error(sk, msg, len, addr_len);
 685
 686         skb = skb_recv_datagram(sk, flags, noblock, &err);
 687         if (!skb)
 688                 goto out;
 689
 690         copied = skb->len;
 691         if (len < copied) {
 692                 msg->msg_flags |= MSG_TRUNC;
 693                 copied = len;
 694         }
 695
 696         err = skb_copy_datagram_msg(skb, 0, msg, copied);
 697         if (err)
 698                 goto done;
 699
 700         sock_recv_timestamp(msg, sk, skb);
 701
 702         /* Copy the address. */
 703         if (lsa) {
 704                 lsa->l2tp_family = AF_INET6;
 705                 lsa->l2tp_unused = 0;
 706                 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
 707                 lsa->l2tp_flowinfo = 0;
 708                 lsa->l2tp_scope_id = 0;
 709                 lsa->l2tp_conn_id = 0;
 710                 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 711                         lsa->l2tp_scope_id = inet6_iif(skb);
 712         }
 713
 714         if (np->rxopt.all)
 715                 ip6_datagram_recv_ctl(sk, msg, skb);
 716
 717         if (flags & MSG_TRUNC)
 718                 copied = skb->len;
 719 done:
 720         skb_free_datagram(sk, skb);
 721 out:
 722         return err ? err : copied;
 723 }
 724
 725 static struct proto l2tp_ip6_prot = {
 726         .name              = "L2TP/IPv6",
 727         .owner             = THIS_MODULE,
 728         .init              = l2tp_ip6_open,
 729         .close             = l2tp_ip6_close,
 730         .bind              = l2tp_ip6_bind,
 731         .connect           = l2tp_ip6_connect,
 732         .disconnect        = l2tp_ip6_disconnect,
 733         .ioctl             = l2tp_ioctl,
 734         .destroy           = l2tp_ip6_destroy_sock,
 735         .setsockopt        = ipv6_setsockopt,
 736         .getsockopt        = ipv6_getsockopt,
 737         .sendmsg           = l2tp_ip6_sendmsg,
 738         .recvmsg           = l2tp_ip6_recvmsg,
 739         .backlog_rcv       = l2tp_ip6_backlog_recv,
 740         .hash              = inet6_hash,
 741         .unhash            = inet_unhash,
 742         .obj_size          = sizeof(struct l2tp_ip6_sock),
 743 #ifdef CONFIG_COMPAT
 744         .compat_setsockopt = compat_ipv6_setsockopt,
 745         .compat_getsockopt = compat_ipv6_getsockopt,
 746 #endif
 747 };
 748
 749 static const struct proto_ops l2tp_ip6_ops = {
 750         .family            = PF_INET6,
 751         .owner             = THIS_MODULE,
 752         .release           = inet6_release,
 753         .bind              = inet6_bind,
 754         .connect           = inet_dgram_connect,
 755         .socketpair        = sock_no_socketpair,
 756         .accept            = sock_no_accept,
 757         .getname           = l2tp_ip6_getname,
 758         .poll              = datagram_poll,
 759         .ioctl             = inet6_ioctl,
 760         .listen            = sock_no_listen,
 761         .shutdown          = inet_shutdown,
 762         .setsockopt        = sock_common_setsockopt,
 763         .getsockopt        = sock_common_getsockopt,
 764         .sendmsg           = inet_sendmsg,
 765         .recvmsg           = sock_common_recvmsg,
 766         .mmap              = sock_no_mmap,
 767         .sendpage          = sock_no_sendpage,
 768 #ifdef CONFIG_COMPAT
 769         .compat_setsockopt = compat_sock_common_setsockopt,
 770         .compat_getsockopt = compat_sock_common_getsockopt,
 771 #endif
 772 };
 773
 774 static struct inet_protosw l2tp_ip6_protosw = {
 775         .type           = SOCK_DGRAM,
 776         .protocol       = IPPROTO_L2TP,
 777         .prot           = &l2tp_ip6_prot,
 778         .ops            = &l2tp_ip6_ops,
 779 };
 780
 781 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
 782         .handler        = l2tp_ip6_recv,
 783 };
 784
 785 static int __init l2tp_ip6_init(void)
 786 {
 787         int err;
 788
 789         pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
 790
 791         err = proto_register(&l2tp_ip6_prot, 1);
 792         if (err != 0)
 793                 goto out;
 794
 795         err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 796         if (err)
 797                 goto out1;
 798
 799         inet6_register_protosw(&l2tp_ip6_protosw);
 800         return 0;
 801
 802 out1:
 803         proto_unregister(&l2tp_ip6_prot);
 804 out:
 805         return err;
 806 }
 807
 808 static void __exit l2tp_ip6_exit(void)
 809 {
 810         inet6_unregister_protosw(&l2tp_ip6_protosw);
 811         inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 812         proto_unregister(&l2tp_ip6_prot);
 813 }
 814
 815 module_init(l2tp_ip6_init);
 816 module_exit(l2tp_ip6_exit);
 817
 818 MODULE_LICENSE("GPL");
 819 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
 820 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
 821 MODULE_VERSION("1.0");
 822
 823 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 824  * enums
 825  */
 826 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
 827 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);