linux/net/l2tp/l2tp_ip6.c
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   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
  39struct 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
  51static DEFINE_RWLOCK(l2tp_ip6_lock);
  52static struct hlist_head l2tp_ip6_table;
  53static struct hlist_head l2tp_ip6_bind_table;
  54
  55static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
  56{
  57        return (struct l2tp_ip6_sock *)sk;
  58}
  59
  60static 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;
  81found:
  82        return sk;
  83}
  84
  85static 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 */
 129static int l2tp_ip6_recv(struct sk_buff *skb)
 130{
 131        struct net *net = dev_net(skb->dev);
 132        struct sock *sk;
 133        u32 session_id;
 134        u32 tunnel_id;
 135        unsigned char *ptr, *optr;
 136        struct l2tp_session *session;
 137        struct l2tp_tunnel *tunnel = NULL;
 138        int length;
 139
 140        if (!pskb_may_pull(skb, 4))
 141                goto discard;
 142
 143        /* Point to L2TP header */
 144        optr = ptr = skb->data;
 145        session_id = ntohl(*((__be32 *) ptr));
 146        ptr += 4;
 147
 148        /* RFC3931: L2TP/IP packets have the first 4 bytes containing
 149         * the session_id. If it is 0, the packet is a L2TP control
 150         * frame and the session_id value can be discarded.
 151         */
 152        if (session_id == 0) {
 153                __skb_pull(skb, 4);
 154                goto pass_up;
 155        }
 156
 157        /* Ok, this is a data packet. Lookup the session. */
 158        session = l2tp_session_find(net, NULL, session_id);
 159        if (session == NULL)
 160                goto discard;
 161
 162        tunnel = session->tunnel;
 163        if (tunnel == NULL)
 164                goto discard;
 165
 166        /* Trace packet contents, if enabled */
 167        if (tunnel->debug & L2TP_MSG_DATA) {
 168                length = min(32u, skb->len);
 169                if (!pskb_may_pull(skb, length))
 170                        goto discard;
 171
 172                /* Point to L2TP header */
 173                optr = ptr = skb->data;
 174                ptr += 4;
 175                pr_debug("%s: ip recv\n", tunnel->name);
 176                print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
 177        }
 178
 179        l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
 180                         tunnel->recv_payload_hook);
 181        return 0;
 182
 183pass_up:
 184        /* Get the tunnel_id from the L2TP header */
 185        if (!pskb_may_pull(skb, 12))
 186                goto discard;
 187
 188        if ((skb->data[0] & 0xc0) != 0xc0)
 189                goto discard;
 190
 191        tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
 192        tunnel = l2tp_tunnel_find(net, tunnel_id);
 193        if (tunnel != NULL)
 194                sk = tunnel->sock;
 195        else {
 196                struct ipv6hdr *iph = ipv6_hdr(skb);
 197
 198                read_lock_bh(&l2tp_ip6_lock);
 199                sk = __l2tp_ip6_bind_lookup(net, &iph->daddr,
 200                                            0, tunnel_id);
 201                read_unlock_bh(&l2tp_ip6_lock);
 202        }
 203
 204        if (sk == NULL)
 205                goto discard;
 206
 207        sock_hold(sk);
 208
 209        if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
 210                goto discard_put;
 211
 212        nf_reset(skb);
 213
 214        return sk_receive_skb(sk, skb, 1);
 215
 216discard_put:
 217        sock_put(sk);
 218
 219discard:
 220        kfree_skb(skb);
 221        return 0;
 222}
 223
 224static int l2tp_ip6_open(struct sock *sk)
 225{
 226        /* Prevent autobind. We don't have ports. */
 227        inet_sk(sk)->inet_num = IPPROTO_L2TP;
 228
 229        write_lock_bh(&l2tp_ip6_lock);
 230        sk_add_node(sk, &l2tp_ip6_table);
 231        write_unlock_bh(&l2tp_ip6_lock);
 232
 233        return 0;
 234}
 235
 236static void l2tp_ip6_close(struct sock *sk, long timeout)
 237{
 238        write_lock_bh(&l2tp_ip6_lock);
 239        hlist_del_init(&sk->sk_bind_node);
 240        sk_del_node_init(sk);
 241        write_unlock_bh(&l2tp_ip6_lock);
 242
 243        sk_common_release(sk);
 244}
 245
 246static void l2tp_ip6_destroy_sock(struct sock *sk)
 247{
 248        struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
 249
 250        lock_sock(sk);
 251        ip6_flush_pending_frames(sk);
 252        release_sock(sk);
 253
 254        if (tunnel) {
 255                l2tp_tunnel_closeall(tunnel);
 256                sock_put(sk);
 257        }
 258
 259        inet6_destroy_sock(sk);
 260}
 261
 262static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 263{
 264        struct inet_sock *inet = inet_sk(sk);
 265        struct ipv6_pinfo *np = inet6_sk(sk);
 266        struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
 267        struct net *net = sock_net(sk);
 268        __be32 v4addr = 0;
 269        int addr_type;
 270        int err;
 271
 272        if (!sock_flag(sk, SOCK_ZAPPED))
 273                return -EINVAL;
 274        if (addr->l2tp_family != AF_INET6)
 275                return -EINVAL;
 276        if (addr_len < sizeof(*addr))
 277                return -EINVAL;
 278
 279        addr_type = ipv6_addr_type(&addr->l2tp_addr);
 280
 281        /* l2tp_ip6 sockets are IPv6 only */
 282        if (addr_type == IPV6_ADDR_MAPPED)
 283                return -EADDRNOTAVAIL;
 284
 285        /* L2TP is point-point, not multicast */
 286        if (addr_type & IPV6_ADDR_MULTICAST)
 287                return -EADDRNOTAVAIL;
 288
 289        err = -EADDRINUSE;
 290        read_lock_bh(&l2tp_ip6_lock);
 291        if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr,
 292                                   sk->sk_bound_dev_if, addr->l2tp_conn_id))
 293                goto out_in_use;
 294        read_unlock_bh(&l2tp_ip6_lock);
 295
 296        lock_sock(sk);
 297
 298        err = -EINVAL;
 299        if (sk->sk_state != TCP_CLOSE)
 300                goto out_unlock;
 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_len >= sizeof(struct sockaddr_in6) &&
 309                            addr->l2tp_scope_id) {
 310                                /* Override any existing binding, if another
 311                                 * one is supplied by user.
 312                                 */
 313                                sk->sk_bound_dev_if = addr->l2tp_scope_id;
 314                        }
 315
 316                        /* Binding to link-local address requires an
 317                           interface */
 318                        if (!sk->sk_bound_dev_if)
 319                                goto out_unlock_rcu;
 320
 321                        err = -ENODEV;
 322                        dev = dev_get_by_index_rcu(sock_net(sk),
 323                                                   sk->sk_bound_dev_if);
 324                        if (!dev)
 325                                goto out_unlock_rcu;
 326                }
 327
 328                /* ipv4 addr of the socket is invalid.  Only the
 329                 * unspecified and mapped address have a v4 equivalent.
 330                 */
 331                v4addr = LOOPBACK4_IPV6;
 332                err = -EADDRNOTAVAIL;
 333                if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
 334                        goto out_unlock_rcu;
 335        }
 336        rcu_read_unlock();
 337
 338        inet->inet_rcv_saddr = inet->inet_saddr = v4addr;
 339        sk->sk_v6_rcv_saddr = addr->l2tp_addr;
 340        np->saddr = addr->l2tp_addr;
 341
 342        l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
 343
 344        write_lock_bh(&l2tp_ip6_lock);
 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
 353out_unlock_rcu:
 354        rcu_read_unlock();
 355out_unlock:
 356        release_sock(sk);
 357        return err;
 358
 359out_in_use:
 360        read_unlock_bh(&l2tp_ip6_lock);
 361        return err;
 362}
 363
 364static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
 365                            int addr_len)
 366{
 367        struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
 368        struct sockaddr_in6     *usin = (struct sockaddr_in6 *) uaddr;
 369        struct in6_addr *daddr;
 370        int     addr_type;
 371        int rc;
 372
 373        if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
 374                return -EINVAL;
 375
 376        if (addr_len < sizeof(*lsa))
 377                return -EINVAL;
 378
 379        if (usin->sin6_family != AF_INET6)
 380                return -EINVAL;
 381
 382        addr_type = ipv6_addr_type(&usin->sin6_addr);
 383        if (addr_type & IPV6_ADDR_MULTICAST)
 384                return -EINVAL;
 385
 386        if (addr_type & IPV6_ADDR_MAPPED) {
 387                daddr = &usin->sin6_addr;
 388                if (ipv4_is_multicast(daddr->s6_addr32[3]))
 389                        return -EINVAL;
 390        }
 391
 392        rc = ip6_datagram_connect(sk, uaddr, addr_len);
 393
 394        lock_sock(sk);
 395
 396        l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 397
 398        write_lock_bh(&l2tp_ip6_lock);
 399        hlist_del_init(&sk->sk_bind_node);
 400        sk_add_bind_node(sk, &l2tp_ip6_bind_table);
 401        write_unlock_bh(&l2tp_ip6_lock);
 402
 403        release_sock(sk);
 404
 405        return rc;
 406}
 407
 408static int l2tp_ip6_disconnect(struct sock *sk, int flags)
 409{
 410        if (sock_flag(sk, SOCK_ZAPPED))
 411                return 0;
 412
 413        return udp_disconnect(sk, flags);
 414}
 415
 416static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
 417                            int *uaddr_len, int peer)
 418{
 419        struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
 420        struct sock *sk = sock->sk;
 421        struct ipv6_pinfo *np = inet6_sk(sk);
 422        struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
 423
 424        lsa->l2tp_family = AF_INET6;
 425        lsa->l2tp_flowinfo = 0;
 426        lsa->l2tp_scope_id = 0;
 427        lsa->l2tp_unused = 0;
 428        if (peer) {
 429                if (!lsk->peer_conn_id)
 430                        return -ENOTCONN;
 431                lsa->l2tp_conn_id = lsk->peer_conn_id;
 432                lsa->l2tp_addr = sk->sk_v6_daddr;
 433                if (np->sndflow)
 434                        lsa->l2tp_flowinfo = np->flow_label;
 435        } else {
 436                if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
 437                        lsa->l2tp_addr = np->saddr;
 438                else
 439                        lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
 440
 441                lsa->l2tp_conn_id = lsk->conn_id;
 442        }
 443        if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 444                lsa->l2tp_scope_id = sk->sk_bound_dev_if;
 445        *uaddr_len = sizeof(*lsa);
 446        return 0;
 447}
 448
 449static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
 450{
 451        int rc;
 452
 453        /* Charge it to the socket, dropping if the queue is full. */
 454        rc = sock_queue_rcv_skb(sk, skb);
 455        if (rc < 0)
 456                goto drop;
 457
 458        return 0;
 459
 460drop:
 461        IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
 462        kfree_skb(skb);
 463        return -1;
 464}
 465
 466static int l2tp_ip6_push_pending_frames(struct sock *sk)
 467{
 468        struct sk_buff *skb;
 469        __be32 *transhdr = NULL;
 470        int err = 0;
 471
 472        skb = skb_peek(&sk->sk_write_queue);
 473        if (skb == NULL)
 474                goto out;
 475
 476        transhdr = (__be32 *)skb_transport_header(skb);
 477        *transhdr = 0;
 478
 479        err = ip6_push_pending_frames(sk);
 480
 481out:
 482        return err;
 483}
 484
 485/* Userspace will call sendmsg() on the tunnel socket to send L2TP
 486 * control frames.
 487 */
 488static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 489{
 490        struct ipv6_txoptions opt_space;
 491        DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 492        struct in6_addr *daddr, *final_p, final;
 493        struct ipv6_pinfo *np = inet6_sk(sk);
 494        struct ipv6_txoptions *opt_to_free = NULL;
 495        struct ipv6_txoptions *opt = NULL;
 496        struct ip6_flowlabel *flowlabel = NULL;
 497        struct dst_entry *dst = NULL;
 498        struct flowi6 fl6;
 499        struct sockcm_cookie sockc_unused = {0};
 500        struct ipcm6_cookie ipc6;
 501        int addr_len = msg->msg_namelen;
 502        int transhdrlen = 4; /* zero session-id */
 503        int ulen = len + transhdrlen;
 504        int err;
 505
 506        /* Rough check on arithmetic overflow,
 507           better check is made in ip6_append_data().
 508         */
 509        if (len > INT_MAX)
 510                return -EMSGSIZE;
 511
 512        /* Mirror BSD error message compatibility */
 513        if (msg->msg_flags & MSG_OOB)
 514                return -EOPNOTSUPP;
 515
 516        /*
 517         *      Get and verify the address.
 518         */
 519        memset(&fl6, 0, sizeof(fl6));
 520
 521        fl6.flowi6_mark = sk->sk_mark;
 522
 523        ipc6.hlimit = -1;
 524        ipc6.tclass = -1;
 525        ipc6.dontfrag = -1;
 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 (flowlabel == NULL)
 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                                            &sockc_unused);
 575                if (err < 0) {
 576                        fl6_sock_release(flowlabel);
 577                        return err;
 578                }
 579                if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
 580                        flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
 581                        if (flowlabel == NULL)
 582                                return -EINVAL;
 583                }
 584                if (!(opt->opt_nflen|opt->opt_flen))
 585                        opt = NULL;
 586        }
 587
 588        if (!opt) {
 589                opt = txopt_get(np);
 590                opt_to_free = opt;
 591        }
 592        if (flowlabel)
 593                opt = fl6_merge_options(&opt_space, flowlabel, opt);
 594        opt = ipv6_fixup_options(&opt_space, opt);
 595        ipc6.opt = opt;
 596
 597        fl6.flowi6_proto = sk->sk_protocol;
 598        if (!ipv6_addr_any(daddr))
 599                fl6.daddr = *daddr;
 600        else
 601                fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
 602        if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
 603                fl6.saddr = np->saddr;
 604
 605        final_p = fl6_update_dst(&fl6, opt, &final);
 606
 607        if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 608                fl6.flowi6_oif = np->mcast_oif;
 609        else if (!fl6.flowi6_oif)
 610                fl6.flowi6_oif = np->ucast_oif;
 611
 612        security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 613
 614        dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
 615        if (IS_ERR(dst)) {
 616                err = PTR_ERR(dst);
 617                goto out;
 618        }
 619
 620        if (ipc6.hlimit < 0)
 621                ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
 622
 623        if (ipc6.tclass < 0)
 624                ipc6.tclass = np->tclass;
 625
 626        if (ipc6.dontfrag < 0)
 627                ipc6.dontfrag = np->dontfrag;
 628
 629        if (msg->msg_flags & MSG_CONFIRM)
 630                goto do_confirm;
 631
 632back_from_confirm:
 633        lock_sock(sk);
 634        err = ip6_append_data(sk, ip_generic_getfrag, msg,
 635                              ulen, transhdrlen, &ipc6,
 636                              &fl6, (struct rt6_info *)dst,
 637                              msg->msg_flags, &sockc_unused);
 638        if (err)
 639                ip6_flush_pending_frames(sk);
 640        else if (!(msg->msg_flags & MSG_MORE))
 641                err = l2tp_ip6_push_pending_frames(sk);
 642        release_sock(sk);
 643done:
 644        dst_release(dst);
 645out:
 646        fl6_sock_release(flowlabel);
 647        txopt_put(opt_to_free);
 648
 649        return err < 0 ? err : len;
 650
 651do_confirm:
 652        dst_confirm(dst);
 653        if (!(msg->msg_flags & MSG_PROBE) || len)
 654                goto back_from_confirm;
 655        err = 0;
 656        goto done;
 657}
 658
 659static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 660                            int noblock, int flags, int *addr_len)
 661{
 662        struct ipv6_pinfo *np = inet6_sk(sk);
 663        DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
 664        size_t copied = 0;
 665        int err = -EOPNOTSUPP;
 666        struct sk_buff *skb;
 667
 668        if (flags & MSG_OOB)
 669                goto out;
 670
 671        if (addr_len)
 672                *addr_len = sizeof(*lsa);
 673
 674        if (flags & MSG_ERRQUEUE)
 675                return ipv6_recv_error(sk, msg, len, addr_len);
 676
 677        skb = skb_recv_datagram(sk, flags, noblock, &err);
 678        if (!skb)
 679                goto out;
 680
 681        copied = skb->len;
 682        if (len < copied) {
 683                msg->msg_flags |= MSG_TRUNC;
 684                copied = len;
 685        }
 686
 687        err = skb_copy_datagram_msg(skb, 0, msg, copied);
 688        if (err)
 689                goto done;
 690
 691        sock_recv_timestamp(msg, sk, skb);
 692
 693        /* Copy the address. */
 694        if (lsa) {
 695                lsa->l2tp_family = AF_INET6;
 696                lsa->l2tp_unused = 0;
 697                lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
 698                lsa->l2tp_flowinfo = 0;
 699                lsa->l2tp_scope_id = 0;
 700                lsa->l2tp_conn_id = 0;
 701                if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
 702                        lsa->l2tp_scope_id = inet6_iif(skb);
 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;
 710done:
 711        skb_free_datagram(sk, skb);
 712out:
 713        return err ? err : copied;
 714}
 715
 716static 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             = udp_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
 740static 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        .listen            = sock_no_listen,
 752        .shutdown          = inet_shutdown,
 753        .setsockopt        = sock_common_setsockopt,
 754        .getsockopt        = sock_common_getsockopt,
 755        .sendmsg           = inet_sendmsg,
 756        .recvmsg           = sock_common_recvmsg,
 757        .mmap              = sock_no_mmap,
 758        .sendpage          = sock_no_sendpage,
 759#ifdef CONFIG_COMPAT
 760        .compat_setsockopt = compat_sock_common_setsockopt,
 761        .compat_getsockopt = compat_sock_common_getsockopt,
 762#endif
 763};
 764
 765static struct inet_protosw l2tp_ip6_protosw = {
 766        .type           = SOCK_DGRAM,
 767        .protocol       = IPPROTO_L2TP,
 768        .prot           = &l2tp_ip6_prot,
 769        .ops            = &l2tp_ip6_ops,
 770};
 771
 772static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
 773        .handler        = l2tp_ip6_recv,
 774};
 775
 776static int __init l2tp_ip6_init(void)
 777{
 778        int err;
 779
 780        pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
 781
 782        err = proto_register(&l2tp_ip6_prot, 1);
 783        if (err != 0)
 784                goto out;
 785
 786        err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 787        if (err)
 788                goto out1;
 789
 790        inet6_register_protosw(&l2tp_ip6_protosw);
 791        return 0;
 792
 793out1:
 794        proto_unregister(&l2tp_ip6_prot);
 795out:
 796        return err;
 797}
 798
 799static void __exit l2tp_ip6_exit(void)
 800{
 801        inet6_unregister_protosw(&l2tp_ip6_protosw);
 802        inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
 803        proto_unregister(&l2tp_ip6_prot);
 804}
 805
 806module_init(l2tp_ip6_init);
 807module_exit(l2tp_ip6_exit);
 808
 809MODULE_LICENSE("GPL");
 810MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
 811MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
 812MODULE_VERSION("1.0");
 813
 814/* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 815 * enums
 816 */
 817MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
 818MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);
 819