linux/net/l2tp/l2tp_ip.c
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   1/*
   2 * L2TPv3 IP encapsulation support
   3 *
   4 * Copyright (c) 2008,2009,2010 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 <net/sock.h>
  22#include <net/ip.h>
  23#include <net/icmp.h>
  24#include <net/udp.h>
  25#include <net/inet_common.h>
  26#include <net/inet_hashtables.h>
  27#include <net/tcp_states.h>
  28#include <net/protocol.h>
  29#include <net/xfrm.h>
  30
  31#include "l2tp_core.h"
  32
  33struct l2tp_ip_sock {
  34        /* inet_sock has to be the first member of l2tp_ip_sock */
  35        struct inet_sock        inet;
  36
  37        u32                     conn_id;
  38        u32                     peer_conn_id;
  39};
  40
  41static DEFINE_RWLOCK(l2tp_ip_lock);
  42static struct hlist_head l2tp_ip_table;
  43static struct hlist_head l2tp_ip_bind_table;
  44
  45static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
  46{
  47        return (struct l2tp_ip_sock *)sk;
  48}
  49
  50static struct sock *__l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
  51{
  52        struct sock *sk;
  53
  54        sk_for_each_bound(sk, &l2tp_ip_bind_table) {
  55                struct inet_sock *inet = inet_sk(sk);
  56                struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
  57
  58                if (l2tp == NULL)
  59                        continue;
  60
  61                if ((l2tp->conn_id == tunnel_id) &&
  62                    net_eq(sock_net(sk), net) &&
  63                    !(inet->inet_rcv_saddr && inet->inet_rcv_saddr != laddr) &&
  64                    !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif))
  65                        goto found;
  66        }
  67
  68        sk = NULL;
  69found:
  70        return sk;
  71}
  72
  73static inline struct sock *l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
  74{
  75        struct sock *sk = __l2tp_ip_bind_lookup(net, laddr, dif, tunnel_id);
  76        if (sk)
  77                sock_hold(sk);
  78
  79        return sk;
  80}
  81
  82/* When processing receive frames, there are two cases to
  83 * consider. Data frames consist of a non-zero session-id and an
  84 * optional cookie. Control frames consist of a regular L2TP header
  85 * preceded by 32-bits of zeros.
  86 *
  87 * L2TPv3 Session Header Over IP
  88 *
  89 *  0                   1                   2                   3
  90 *  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
  91 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  92 * |                           Session ID                          |
  93 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  94 * |               Cookie (optional, maximum 64 bits)...
  95 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  96 *                                                                 |
  97 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  98 *
  99 * L2TPv3 Control Message Header Over IP
 100 *
 101 *  0                   1                   2                   3
 102 *  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
 103 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 104 * |                      (32 bits of zeros)                       |
 105 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 106 * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
 107 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 108 * |                     Control Connection ID                     |
 109 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 110 * |               Ns              |               Nr              |
 111 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 112 *
 113 * All control frames are passed to userspace.
 114 */
 115static int l2tp_ip_recv(struct sk_buff *skb)
 116{
 117        struct net *net = dev_net(skb->dev);
 118        struct sock *sk;
 119        u32 session_id;
 120        u32 tunnel_id;
 121        unsigned char *ptr, *optr;
 122        struct l2tp_session *session;
 123        struct l2tp_tunnel *tunnel = NULL;
 124        int length;
 125
 126        /* Point to L2TP header */
 127        optr = ptr = skb->data;
 128
 129        if (!pskb_may_pull(skb, 4))
 130                goto discard;
 131
 132        session_id = ntohl(*((__be32 *) ptr));
 133        ptr += 4;
 134
 135        /* RFC3931: L2TP/IP packets have the first 4 bytes containing
 136         * the session_id. If it is 0, the packet is a L2TP control
 137         * frame and the session_id value can be discarded.
 138         */
 139        if (session_id == 0) {
 140                __skb_pull(skb, 4);
 141                goto pass_up;
 142        }
 143
 144        /* Ok, this is a data packet. Lookup the session. */
 145        session = l2tp_session_find(net, NULL, session_id);
 146        if (session == NULL)
 147                goto discard;
 148
 149        tunnel = session->tunnel;
 150        if (tunnel == NULL)
 151                goto discard;
 152
 153        /* Trace packet contents, if enabled */
 154        if (tunnel->debug & L2TP_MSG_DATA) {
 155                length = min(32u, skb->len);
 156                if (!pskb_may_pull(skb, length))
 157                        goto discard;
 158
 159                pr_debug("%s: ip recv\n", tunnel->name);
 160                print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
 161        }
 162
 163        l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook);
 164
 165        return 0;
 166
 167pass_up:
 168        /* Get the tunnel_id from the L2TP header */
 169        if (!pskb_may_pull(skb, 12))
 170                goto discard;
 171
 172        if ((skb->data[0] & 0xc0) != 0xc0)
 173                goto discard;
 174
 175        tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
 176        tunnel = l2tp_tunnel_find(net, tunnel_id);
 177        if (tunnel != NULL)
 178                sk = tunnel->sock;
 179        else {
 180                struct iphdr *iph = (struct iphdr *) skb_network_header(skb);
 181
 182                read_lock_bh(&l2tp_ip_lock);
 183                sk = __l2tp_ip_bind_lookup(net, iph->daddr, 0, tunnel_id);
 184                read_unlock_bh(&l2tp_ip_lock);
 185        }
 186
 187        if (sk == NULL)
 188                goto discard;
 189
 190        sock_hold(sk);
 191
 192        if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
 193                goto discard_put;
 194
 195        nf_reset(skb);
 196
 197        return sk_receive_skb(sk, skb, 1);
 198
 199discard_put:
 200        sock_put(sk);
 201
 202discard:
 203        kfree_skb(skb);
 204        return 0;
 205}
 206
 207static int l2tp_ip_open(struct sock *sk)
 208{
 209        /* Prevent autobind. We don't have ports. */
 210        inet_sk(sk)->inet_num = IPPROTO_L2TP;
 211
 212        write_lock_bh(&l2tp_ip_lock);
 213        sk_add_node(sk, &l2tp_ip_table);
 214        write_unlock_bh(&l2tp_ip_lock);
 215
 216        return 0;
 217}
 218
 219static void l2tp_ip_close(struct sock *sk, long timeout)
 220{
 221        write_lock_bh(&l2tp_ip_lock);
 222        hlist_del_init(&sk->sk_bind_node);
 223        sk_del_node_init(sk);
 224        write_unlock_bh(&l2tp_ip_lock);
 225        sk_common_release(sk);
 226}
 227
 228static void l2tp_ip_destroy_sock(struct sock *sk)
 229{
 230        struct sk_buff *skb;
 231        struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
 232
 233        while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
 234                kfree_skb(skb);
 235
 236        if (tunnel) {
 237                l2tp_tunnel_closeall(tunnel);
 238                sock_put(sk);
 239        }
 240
 241        sk_refcnt_debug_dec(sk);
 242}
 243
 244static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 245{
 246        struct inet_sock *inet = inet_sk(sk);
 247        struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
 248        struct net *net = sock_net(sk);
 249        int ret;
 250        int chk_addr_ret;
 251
 252        if (!sock_flag(sk, SOCK_ZAPPED))
 253                return -EINVAL;
 254        if (addr_len < sizeof(struct sockaddr_l2tpip))
 255                return -EINVAL;
 256        if (addr->l2tp_family != AF_INET)
 257                return -EINVAL;
 258
 259        ret = -EADDRINUSE;
 260        read_lock_bh(&l2tp_ip_lock);
 261        if (__l2tp_ip_bind_lookup(net, addr->l2tp_addr.s_addr,
 262                                  sk->sk_bound_dev_if, addr->l2tp_conn_id))
 263                goto out_in_use;
 264
 265        read_unlock_bh(&l2tp_ip_lock);
 266
 267        lock_sock(sk);
 268        if (sk->sk_state != TCP_CLOSE || addr_len < sizeof(struct sockaddr_l2tpip))
 269                goto out;
 270
 271        chk_addr_ret = inet_addr_type(net, addr->l2tp_addr.s_addr);
 272        ret = -EADDRNOTAVAIL;
 273        if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
 274            chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
 275                goto out;
 276
 277        if (addr->l2tp_addr.s_addr)
 278                inet->inet_rcv_saddr = inet->inet_saddr = addr->l2tp_addr.s_addr;
 279        if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
 280                inet->inet_saddr = 0;  /* Use device */
 281        sk_dst_reset(sk);
 282
 283        l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
 284
 285        write_lock_bh(&l2tp_ip_lock);
 286        sk_add_bind_node(sk, &l2tp_ip_bind_table);
 287        sk_del_node_init(sk);
 288        write_unlock_bh(&l2tp_ip_lock);
 289        ret = 0;
 290        sock_reset_flag(sk, SOCK_ZAPPED);
 291
 292out:
 293        release_sock(sk);
 294
 295        return ret;
 296
 297out_in_use:
 298        read_unlock_bh(&l2tp_ip_lock);
 299
 300        return ret;
 301}
 302
 303static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 304{
 305        struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
 306        int rc;
 307
 308        if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
 309                return -EINVAL;
 310
 311        if (addr_len < sizeof(*lsa))
 312                return -EINVAL;
 313
 314        if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
 315                return -EINVAL;
 316
 317        rc = ip4_datagram_connect(sk, uaddr, addr_len);
 318        if (rc < 0)
 319                return rc;
 320
 321        lock_sock(sk);
 322
 323        l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 324
 325        write_lock_bh(&l2tp_ip_lock);
 326        hlist_del_init(&sk->sk_bind_node);
 327        sk_add_bind_node(sk, &l2tp_ip_bind_table);
 328        write_unlock_bh(&l2tp_ip_lock);
 329
 330        release_sock(sk);
 331        return rc;
 332}
 333
 334static int l2tp_ip_disconnect(struct sock *sk, int flags)
 335{
 336        if (sock_flag(sk, SOCK_ZAPPED))
 337                return 0;
 338
 339        return udp_disconnect(sk, flags);
 340}
 341
 342static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
 343                           int *uaddr_len, int peer)
 344{
 345        struct sock *sk         = sock->sk;
 346        struct inet_sock *inet  = inet_sk(sk);
 347        struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
 348        struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
 349
 350        memset(lsa, 0, sizeof(*lsa));
 351        lsa->l2tp_family = AF_INET;
 352        if (peer) {
 353                if (!inet->inet_dport)
 354                        return -ENOTCONN;
 355                lsa->l2tp_conn_id = lsk->peer_conn_id;
 356                lsa->l2tp_addr.s_addr = inet->inet_daddr;
 357        } else {
 358                __be32 addr = inet->inet_rcv_saddr;
 359                if (!addr)
 360                        addr = inet->inet_saddr;
 361                lsa->l2tp_conn_id = lsk->conn_id;
 362                lsa->l2tp_addr.s_addr = addr;
 363        }
 364        *uaddr_len = sizeof(*lsa);
 365        return 0;
 366}
 367
 368static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
 369{
 370        int rc;
 371
 372        /* Charge it to the socket, dropping if the queue is full. */
 373        rc = sock_queue_rcv_skb(sk, skb);
 374        if (rc < 0)
 375                goto drop;
 376
 377        return 0;
 378
 379drop:
 380        IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
 381        kfree_skb(skb);
 382        return -1;
 383}
 384
 385/* Userspace will call sendmsg() on the tunnel socket to send L2TP
 386 * control frames.
 387 */
 388static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len)
 389{
 390        struct sk_buff *skb;
 391        int rc;
 392        struct inet_sock *inet = inet_sk(sk);
 393        struct rtable *rt = NULL;
 394        struct flowi4 *fl4;
 395        int connected = 0;
 396        __be32 daddr;
 397
 398        lock_sock(sk);
 399
 400        rc = -ENOTCONN;
 401        if (sock_flag(sk, SOCK_DEAD))
 402                goto out;
 403
 404        /* Get and verify the address. */
 405        if (msg->msg_name) {
 406                DECLARE_SOCKADDR(struct sockaddr_l2tpip *, lip, msg->msg_name);
 407                rc = -EINVAL;
 408                if (msg->msg_namelen < sizeof(*lip))
 409                        goto out;
 410
 411                if (lip->l2tp_family != AF_INET) {
 412                        rc = -EAFNOSUPPORT;
 413                        if (lip->l2tp_family != AF_UNSPEC)
 414                                goto out;
 415                }
 416
 417                daddr = lip->l2tp_addr.s_addr;
 418        } else {
 419                rc = -EDESTADDRREQ;
 420                if (sk->sk_state != TCP_ESTABLISHED)
 421                        goto out;
 422
 423                daddr = inet->inet_daddr;
 424                connected = 1;
 425        }
 426
 427        /* Allocate a socket buffer */
 428        rc = -ENOMEM;
 429        skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
 430                           4 + len, 0, GFP_KERNEL);
 431        if (!skb)
 432                goto error;
 433
 434        /* Reserve space for headers, putting IP header on 4-byte boundary. */
 435        skb_reserve(skb, 2 + NET_SKB_PAD);
 436        skb_reset_network_header(skb);
 437        skb_reserve(skb, sizeof(struct iphdr));
 438        skb_reset_transport_header(skb);
 439
 440        /* Insert 0 session_id */
 441        *((__be32 *) skb_put(skb, 4)) = 0;
 442
 443        /* Copy user data into skb */
 444        rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
 445        if (rc < 0) {
 446                kfree_skb(skb);
 447                goto error;
 448        }
 449
 450        fl4 = &inet->cork.fl.u.ip4;
 451        if (connected)
 452                rt = (struct rtable *) __sk_dst_check(sk, 0);
 453
 454        rcu_read_lock();
 455        if (rt == NULL) {
 456                const struct ip_options_rcu *inet_opt;
 457
 458                inet_opt = rcu_dereference(inet->inet_opt);
 459
 460                /* Use correct destination address if we have options. */
 461                if (inet_opt && inet_opt->opt.srr)
 462                        daddr = inet_opt->opt.faddr;
 463
 464                /* If this fails, retransmit mechanism of transport layer will
 465                 * keep trying until route appears or the connection times
 466                 * itself out.
 467                 */
 468                rt = ip_route_output_ports(sock_net(sk), fl4, sk,
 469                                           daddr, inet->inet_saddr,
 470                                           inet->inet_dport, inet->inet_sport,
 471                                           sk->sk_protocol, RT_CONN_FLAGS(sk),
 472                                           sk->sk_bound_dev_if);
 473                if (IS_ERR(rt))
 474                        goto no_route;
 475                if (connected) {
 476                        sk_setup_caps(sk, &rt->dst);
 477                } else {
 478                        skb_dst_set(skb, &rt->dst);
 479                        goto xmit;
 480                }
 481        }
 482
 483        /* We dont need to clone dst here, it is guaranteed to not disappear.
 484         *  __dev_xmit_skb() might force a refcount if needed.
 485         */
 486        skb_dst_set_noref(skb, &rt->dst);
 487
 488xmit:
 489        /* Queue the packet to IP for output */
 490        rc = ip_queue_xmit(skb, &inet->cork.fl);
 491        rcu_read_unlock();
 492
 493error:
 494        if (rc >= 0)
 495                rc = len;
 496
 497out:
 498        release_sock(sk);
 499        return rc;
 500
 501no_route:
 502        rcu_read_unlock();
 503        IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
 504        kfree_skb(skb);
 505        rc = -EHOSTUNREACH;
 506        goto out;
 507}
 508
 509static int l2tp_ip_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 510                           size_t len, int noblock, int flags, int *addr_len)
 511{
 512        struct inet_sock *inet = inet_sk(sk);
 513        size_t copied = 0;
 514        int err = -EOPNOTSUPP;
 515        DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
 516        struct sk_buff *skb;
 517
 518        if (flags & MSG_OOB)
 519                goto out;
 520
 521        skb = skb_recv_datagram(sk, flags, noblock, &err);
 522        if (!skb)
 523                goto out;
 524
 525        copied = skb->len;
 526        if (len < copied) {
 527                msg->msg_flags |= MSG_TRUNC;
 528                copied = len;
 529        }
 530
 531        err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
 532        if (err)
 533                goto done;
 534
 535        sock_recv_timestamp(msg, sk, skb);
 536
 537        /* Copy the address. */
 538        if (sin) {
 539                sin->sin_family = AF_INET;
 540                sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
 541                sin->sin_port = 0;
 542                memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
 543                *addr_len = sizeof(*sin);
 544        }
 545        if (inet->cmsg_flags)
 546                ip_cmsg_recv(msg, skb);
 547        if (flags & MSG_TRUNC)
 548                copied = skb->len;
 549done:
 550        skb_free_datagram(sk, skb);
 551out:
 552        return err ? err : copied;
 553}
 554
 555static struct proto l2tp_ip_prot = {
 556        .name              = "L2TP/IP",
 557        .owner             = THIS_MODULE,
 558        .init              = l2tp_ip_open,
 559        .close             = l2tp_ip_close,
 560        .bind              = l2tp_ip_bind,
 561        .connect           = l2tp_ip_connect,
 562        .disconnect        = l2tp_ip_disconnect,
 563        .ioctl             = udp_ioctl,
 564        .destroy           = l2tp_ip_destroy_sock,
 565        .setsockopt        = ip_setsockopt,
 566        .getsockopt        = ip_getsockopt,
 567        .sendmsg           = l2tp_ip_sendmsg,
 568        .recvmsg           = l2tp_ip_recvmsg,
 569        .backlog_rcv       = l2tp_ip_backlog_recv,
 570        .hash              = inet_hash,
 571        .unhash            = inet_unhash,
 572        .obj_size          = sizeof(struct l2tp_ip_sock),
 573#ifdef CONFIG_COMPAT
 574        .compat_setsockopt = compat_ip_setsockopt,
 575        .compat_getsockopt = compat_ip_getsockopt,
 576#endif
 577};
 578
 579static const struct proto_ops l2tp_ip_ops = {
 580        .family            = PF_INET,
 581        .owner             = THIS_MODULE,
 582        .release           = inet_release,
 583        .bind              = inet_bind,
 584        .connect           = inet_dgram_connect,
 585        .socketpair        = sock_no_socketpair,
 586        .accept            = sock_no_accept,
 587        .getname           = l2tp_ip_getname,
 588        .poll              = datagram_poll,
 589        .ioctl             = inet_ioctl,
 590        .listen            = sock_no_listen,
 591        .shutdown          = inet_shutdown,
 592        .setsockopt        = sock_common_setsockopt,
 593        .getsockopt        = sock_common_getsockopt,
 594        .sendmsg           = inet_sendmsg,
 595        .recvmsg           = sock_common_recvmsg,
 596        .mmap              = sock_no_mmap,
 597        .sendpage          = sock_no_sendpage,
 598#ifdef CONFIG_COMPAT
 599        .compat_setsockopt = compat_sock_common_setsockopt,
 600        .compat_getsockopt = compat_sock_common_getsockopt,
 601#endif
 602};
 603
 604static struct inet_protosw l2tp_ip_protosw = {
 605        .type           = SOCK_DGRAM,
 606        .protocol       = IPPROTO_L2TP,
 607        .prot           = &l2tp_ip_prot,
 608        .ops            = &l2tp_ip_ops,
 609        .no_check       = 0,
 610};
 611
 612static struct net_protocol l2tp_ip_protocol __read_mostly = {
 613        .handler        = l2tp_ip_recv,
 614        .netns_ok       = 1,
 615};
 616
 617static int __init l2tp_ip_init(void)
 618{
 619        int err;
 620
 621        pr_info("L2TP IP encapsulation support (L2TPv3)\n");
 622
 623        err = proto_register(&l2tp_ip_prot, 1);
 624        if (err != 0)
 625                goto out;
 626
 627        err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
 628        if (err)
 629                goto out1;
 630
 631        inet_register_protosw(&l2tp_ip_protosw);
 632        return 0;
 633
 634out1:
 635        proto_unregister(&l2tp_ip_prot);
 636out:
 637        return err;
 638}
 639
 640static void __exit l2tp_ip_exit(void)
 641{
 642        inet_unregister_protosw(&l2tp_ip_protosw);
 643        inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
 644        proto_unregister(&l2tp_ip_prot);
 645}
 646
 647module_init(l2tp_ip_init);
 648module_exit(l2tp_ip_exit);
 649
 650MODULE_LICENSE("GPL");
 651MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 652MODULE_DESCRIPTION("L2TP over IP");
 653MODULE_VERSION("1.0");
 654
 655/* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 656 * enums
 657 */
 658MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP);
 659