net/l2tp/l2tp_ip.c

   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
  33 struct 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
  41 static DEFINE_RWLOCK(l2tp_ip_lock);
  42 static struct hlist_head l2tp_ip_table;
  43 static struct hlist_head l2tp_ip_bind_table;
  44
  45 static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
  46 {
  47         return (struct l2tp_ip_sock *)sk;
  48 }
  49
  50 static 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;
  69 found:
  70         return sk;
  71 }
  72
  73 static 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  */
 115 static 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
 167 pass_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
 199 discard_put:
 200         sock_put(sk);
 201
 202 discard:
 203         kfree_skb(skb);
 204         return 0;
 205 }
 206
 207 static 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
 219 static 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
 228 static void l2tp_ip_destroy_sock(struct sock *sk)
 229 {
 230         struct sk_buff *skb;
 231
 232         while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
 233                 kfree_skb(skb);
 234
 235         sk_refcnt_debug_dec(sk);
 236 }
 237
 238 static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 239 {
 240         struct inet_sock *inet = inet_sk(sk);
 241         struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
 242         struct net *net = sock_net(sk);
 243         int ret;
 244         int chk_addr_ret;
 245
 246         if (!sock_flag(sk, SOCK_ZAPPED))
 247                 return -EINVAL;
 248         if (addr_len < sizeof(struct sockaddr_l2tpip))
 249                 return -EINVAL;
 250         if (addr->l2tp_family != AF_INET)
 251                 return -EINVAL;
 252
 253         ret = -EADDRINUSE;
 254         read_lock_bh(&l2tp_ip_lock);
 255         if (__l2tp_ip_bind_lookup(net, addr->l2tp_addr.s_addr,
 256                                   sk->sk_bound_dev_if, addr->l2tp_conn_id))
 257                 goto out_in_use;
 258
 259         read_unlock_bh(&l2tp_ip_lock);
 260
 261         lock_sock(sk);
 262         if (sk->sk_state != TCP_CLOSE || addr_len < sizeof(struct sockaddr_l2tpip))
 263                 goto out;
 264
 265         chk_addr_ret = inet_addr_type(net, addr->l2tp_addr.s_addr);
 266         ret = -EADDRNOTAVAIL;
 267         if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
 268             chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
 269                 goto out;
 270
 271         if (addr->l2tp_addr.s_addr)
 272                 inet->inet_rcv_saddr = inet->inet_saddr = addr->l2tp_addr.s_addr;
 273         if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
 274                 inet->inet_saddr = 0;  /* Use device */
 275         sk_dst_reset(sk);
 276
 277         l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
 278
 279         write_lock_bh(&l2tp_ip_lock);
 280         sk_add_bind_node(sk, &l2tp_ip_bind_table);
 281         sk_del_node_init(sk);
 282         write_unlock_bh(&l2tp_ip_lock);
 283         ret = 0;
 284         sock_reset_flag(sk, SOCK_ZAPPED);
 285
 286 out:
 287         release_sock(sk);
 288
 289         return ret;
 290
 291 out_in_use:
 292         read_unlock_bh(&l2tp_ip_lock);
 293
 294         return ret;
 295 }
 296
 297 static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 298 {
 299         struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
 300         int rc;
 301
 302         if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
 303                 return -EINVAL;
 304
 305         if (addr_len < sizeof(*lsa))
 306                 return -EINVAL;
 307
 308         if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
 309                 return -EINVAL;
 310
 311         rc = ip4_datagram_connect(sk, uaddr, addr_len);
 312         if (rc < 0)
 313                 return rc;
 314
 315         lock_sock(sk);
 316
 317         l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
 318
 319         write_lock_bh(&l2tp_ip_lock);
 320         hlist_del_init(&sk->sk_bind_node);
 321         sk_add_bind_node(sk, &l2tp_ip_bind_table);
 322         write_unlock_bh(&l2tp_ip_lock);
 323
 324         release_sock(sk);
 325         return rc;
 326 }
 327
 328 static int l2tp_ip_disconnect(struct sock *sk, int flags)
 329 {
 330         if (sock_flag(sk, SOCK_ZAPPED))
 331                 return 0;
 332
 333         return udp_disconnect(sk, flags);
 334 }
 335
 336 static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
 337                            int *uaddr_len, int peer)
 338 {
 339         struct sock *sk         = sock->sk;
 340         struct inet_sock *inet  = inet_sk(sk);
 341         struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
 342         struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
 343
 344         memset(lsa, 0, sizeof(*lsa));
 345         lsa->l2tp_family = AF_INET;
 346         if (peer) {
 347                 if (!inet->inet_dport)
 348                         return -ENOTCONN;
 349                 lsa->l2tp_conn_id = lsk->peer_conn_id;
 350                 lsa->l2tp_addr.s_addr = inet->inet_daddr;
 351         } else {
 352                 __be32 addr = inet->inet_rcv_saddr;
 353                 if (!addr)
 354                         addr = inet->inet_saddr;
 355                 lsa->l2tp_conn_id = lsk->conn_id;
 356                 lsa->l2tp_addr.s_addr = addr;
 357         }
 358         *uaddr_len = sizeof(*lsa);
 359         return 0;
 360 }
 361
 362 static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
 363 {
 364         int rc;
 365
 366         /* Charge it to the socket, dropping if the queue is full. */
 367         rc = sock_queue_rcv_skb(sk, skb);
 368         if (rc < 0)
 369                 goto drop;
 370
 371         return 0;
 372
 373 drop:
 374         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
 375         kfree_skb(skb);
 376         return -1;
 377 }
 378
 379 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
 380  * control frames.
 381  */
 382 static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len)
 383 {
 384         struct sk_buff *skb;
 385         int rc;
 386         struct inet_sock *inet = inet_sk(sk);
 387         struct rtable *rt = NULL;
 388         struct flowi4 *fl4;
 389         int connected = 0;
 390         __be32 daddr;
 391
 392         lock_sock(sk);
 393
 394         rc = -ENOTCONN;
 395         if (sock_flag(sk, SOCK_DEAD))
 396                 goto out;
 397
 398         /* Get and verify the address. */
 399         if (msg->msg_name) {
 400                 struct sockaddr_l2tpip *lip = (struct sockaddr_l2tpip *) msg->msg_name;
 401                 rc = -EINVAL;
 402                 if (msg->msg_namelen < sizeof(*lip))
 403                         goto out;
 404
 405                 if (lip->l2tp_family != AF_INET) {
 406                         rc = -EAFNOSUPPORT;
 407                         if (lip->l2tp_family != AF_UNSPEC)
 408                                 goto out;
 409                 }
 410
 411                 daddr = lip->l2tp_addr.s_addr;
 412         } else {
 413                 rc = -EDESTADDRREQ;
 414                 if (sk->sk_state != TCP_ESTABLISHED)
 415                         goto out;
 416
 417                 daddr = inet->inet_daddr;
 418                 connected = 1;
 419         }
 420
 421         /* Allocate a socket buffer */
 422         rc = -ENOMEM;
 423         skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
 424                            4 + len, 0, GFP_KERNEL);
 425         if (!skb)
 426                 goto error;
 427
 428         /* Reserve space for headers, putting IP header on 4-byte boundary. */
 429         skb_reserve(skb, 2 + NET_SKB_PAD);
 430         skb_reset_network_header(skb);
 431         skb_reserve(skb, sizeof(struct iphdr));
 432         skb_reset_transport_header(skb);
 433
 434         /* Insert 0 session_id */
 435         *((__be32 *) skb_put(skb, 4)) = 0;
 436
 437         /* Copy user data into skb */
 438         rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
 439         if (rc < 0) {
 440                 kfree_skb(skb);
 441                 goto error;
 442         }
 443
 444         fl4 = &inet->cork.fl.u.ip4;
 445         if (connected)
 446                 rt = (struct rtable *) __sk_dst_check(sk, 0);
 447
 448         rcu_read_lock();
 449         if (rt == NULL) {
 450                 const struct ip_options_rcu *inet_opt;
 451
 452                 inet_opt = rcu_dereference(inet->inet_opt);
 453
 454                 /* Use correct destination address if we have options. */
 455                 if (inet_opt && inet_opt->opt.srr)
 456                         daddr = inet_opt->opt.faddr;
 457
 458                 /* If this fails, retransmit mechanism of transport layer will
 459                  * keep trying until route appears or the connection times
 460                  * itself out.
 461                  */
 462                 rt = ip_route_output_ports(sock_net(sk), fl4, sk,
 463                                            daddr, inet->inet_saddr,
 464                                            inet->inet_dport, inet->inet_sport,
 465                                            sk->sk_protocol, RT_CONN_FLAGS(sk),
 466                                            sk->sk_bound_dev_if);
 467                 if (IS_ERR(rt))
 468                         goto no_route;
 469                 if (connected) {
 470                         sk_setup_caps(sk, &rt->dst);
 471                 } else {
 472                         skb_dst_set(skb, &rt->dst);
 473                         goto xmit;
 474                 }
 475         }
 476
 477         /* We dont need to clone dst here, it is guaranteed to not disappear.
 478          *  __dev_xmit_skb() might force a refcount if needed.
 479          */
 480         skb_dst_set_noref(skb, &rt->dst);
 481
 482 xmit:
 483         /* Queue the packet to IP for output */
 484         rc = ip_queue_xmit(skb, &inet->cork.fl);
 485         rcu_read_unlock();
 486
 487 error:
 488         if (rc >= 0)
 489                 rc = len;
 490
 491 out:
 492         release_sock(sk);
 493         return rc;
 494
 495 no_route:
 496         rcu_read_unlock();
 497         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
 498         kfree_skb(skb);
 499         rc = -EHOSTUNREACH;
 500         goto out;
 501 }
 502
 503 static int l2tp_ip_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 504                            size_t len, int noblock, int flags, int *addr_len)
 505 {
 506         struct inet_sock *inet = inet_sk(sk);
 507         size_t copied = 0;
 508         int err = -EOPNOTSUPP;
 509         struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
 510         struct sk_buff *skb;
 511
 512         if (flags & MSG_OOB)
 513                 goto out;
 514
 515         if (addr_len)
 516                 *addr_len = sizeof(*sin);
 517
 518         skb = skb_recv_datagram(sk, flags, noblock, &err);
 519         if (!skb)
 520                 goto out;
 521
 522         copied = skb->len;
 523         if (len < copied) {
 524                 msg->msg_flags |= MSG_TRUNC;
 525                 copied = len;
 526         }
 527
 528         err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
 529         if (err)
 530                 goto done;
 531
 532         sock_recv_timestamp(msg, sk, skb);
 533
 534         /* Copy the address. */
 535         if (sin) {
 536                 sin->sin_family = AF_INET;
 537                 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
 538                 sin->sin_port = 0;
 539                 memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
 540         }
 541         if (inet->cmsg_flags)
 542                 ip_cmsg_recv(msg, skb);
 543         if (flags & MSG_TRUNC)
 544                 copied = skb->len;
 545 done:
 546         skb_free_datagram(sk, skb);
 547 out:
 548         return err ? err : copied;
 549 }
 550
 551 static struct proto l2tp_ip_prot = {
 552         .name              = "L2TP/IP",
 553         .owner             = THIS_MODULE,
 554         .init              = l2tp_ip_open,
 555         .close             = l2tp_ip_close,
 556         .bind              = l2tp_ip_bind,
 557         .connect           = l2tp_ip_connect,
 558         .disconnect        = l2tp_ip_disconnect,
 559         .ioctl             = udp_ioctl,
 560         .destroy           = l2tp_ip_destroy_sock,
 561         .setsockopt        = ip_setsockopt,
 562         .getsockopt        = ip_getsockopt,
 563         .sendmsg           = l2tp_ip_sendmsg,
 564         .recvmsg           = l2tp_ip_recvmsg,
 565         .backlog_rcv       = l2tp_ip_backlog_recv,
 566         .hash              = inet_hash,
 567         .unhash            = inet_unhash,
 568         .obj_size          = sizeof(struct l2tp_ip_sock),
 569 #ifdef CONFIG_COMPAT
 570         .compat_setsockopt = compat_ip_setsockopt,
 571         .compat_getsockopt = compat_ip_getsockopt,
 572 #endif
 573 };
 574
 575 static const struct proto_ops l2tp_ip_ops = {
 576         .family            = PF_INET,
 577         .owner             = THIS_MODULE,
 578         .release           = inet_release,
 579         .bind              = inet_bind,
 580         .connect           = inet_dgram_connect,
 581         .socketpair        = sock_no_socketpair,
 582         .accept            = sock_no_accept,
 583         .getname           = l2tp_ip_getname,
 584         .poll              = datagram_poll,
 585         .ioctl             = inet_ioctl,
 586         .listen            = sock_no_listen,
 587         .shutdown          = inet_shutdown,
 588         .setsockopt        = sock_common_setsockopt,
 589         .getsockopt        = sock_common_getsockopt,
 590         .sendmsg           = inet_sendmsg,
 591         .recvmsg           = sock_common_recvmsg,
 592         .mmap              = sock_no_mmap,
 593         .sendpage          = sock_no_sendpage,
 594 #ifdef CONFIG_COMPAT
 595         .compat_setsockopt = compat_sock_common_setsockopt,
 596         .compat_getsockopt = compat_sock_common_getsockopt,
 597 #endif
 598 };
 599
 600 static struct inet_protosw l2tp_ip_protosw = {
 601         .type           = SOCK_DGRAM,
 602         .protocol       = IPPROTO_L2TP,
 603         .prot           = &l2tp_ip_prot,
 604         .ops            = &l2tp_ip_ops,
 605         .no_check       = 0,
 606 };
 607
 608 static struct net_protocol l2tp_ip_protocol __read_mostly = {
 609         .handler        = l2tp_ip_recv,
 610         .netns_ok       = 1,
 611 };
 612
 613 static int __init l2tp_ip_init(void)
 614 {
 615         int err;
 616
 617         pr_info("L2TP IP encapsulation support (L2TPv3)\n");
 618
 619         err = proto_register(&l2tp_ip_prot, 1);
 620         if (err != 0)
 621                 goto out;
 622
 623         err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
 624         if (err)
 625                 goto out1;
 626
 627         inet_register_protosw(&l2tp_ip_protosw);
 628         return 0;
 629
 630 out1:
 631         proto_unregister(&l2tp_ip_prot);
 632 out:
 633         return err;
 634 }
 635
 636 static void __exit l2tp_ip_exit(void)
 637 {
 638         inet_unregister_protosw(&l2tp_ip_protosw);
 639         inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
 640         proto_unregister(&l2tp_ip_prot);
 641 }
 642
 643 module_init(l2tp_ip_init);
 644 module_exit(l2tp_ip_exit);
 645
 646 MODULE_LICENSE("GPL");
 647 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 648 MODULE_DESCRIPTION("L2TP over IP");
 649 MODULE_VERSION("1.0");
 650
 651 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
 652  * enums
 653  */
 654 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP);