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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* L2TPv3 IP encapsulation support
3 *
4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <asm/ioctls.h>
10#include <linux/icmp.h>
11#include <linux/module.h>
12#include <linux/skbuff.h>
13#include <linux/random.h>
14#include <linux/socket.h>
15#include <linux/l2tp.h>
16#include <linux/in.h>
17#include <net/sock.h>
18#include <net/ip.h>
19#include <net/icmp.h>
20#include <net/udp.h>
21#include <net/inet_common.h>
22#include <net/tcp_states.h>
23#include <net/protocol.h>
24#include <net/xfrm.h>
25
26#include "l2tp_core.h"
27
28struct l2tp_ip_sock {
29 /* inet_sock has to be the first member of l2tp_ip_sock */
30 struct inet_sock inet;
31
32 u32 conn_id;
33 u32 peer_conn_id;
34};
35
36static DEFINE_RWLOCK(l2tp_ip_lock);
37static struct hlist_head l2tp_ip_table;
38static struct hlist_head l2tp_ip_bind_table;
39
40static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
41{
42 return (struct l2tp_ip_sock *)sk;
43}
44
45static struct sock *__l2tp_ip_bind_lookup(const struct net *net, __be32 laddr,
46 __be32 raddr, int dif, u32 tunnel_id)
47{
48 struct sock *sk;
49
50 sk_for_each_bound(sk, &l2tp_ip_bind_table) {
51 const struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
52 const struct inet_sock *inet = inet_sk(sk);
53 int bound_dev_if;
54
55 if (!net_eq(sock_net(sk), net))
56 continue;
57
58 bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
59 if (bound_dev_if && dif && bound_dev_if != dif)
60 continue;
61
62 if (inet->inet_rcv_saddr && laddr &&
63 inet->inet_rcv_saddr != laddr)
64 continue;
65
66 if (inet->inet_daddr && raddr && inet->inet_daddr != raddr)
67 continue;
68
69 if (l2tp->conn_id != tunnel_id)
70 continue;
71
72 goto found;
73 }
74
75 sk = NULL;
76found:
77 return sk;
78}
79
80/* When processing receive frames, there are two cases to
81 * consider. Data frames consist of a non-zero session-id and an
82 * optional cookie. Control frames consist of a regular L2TP header
83 * preceded by 32-bits of zeros.
84 *
85 * L2TPv3 Session Header Over IP
86 *
87 * 0 1 2 3
88 * 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
89 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
90 * | Session ID |
91 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
92 * | Cookie (optional, maximum 64 bits)...
93 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
94 * |
95 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
96 *
97 * L2TPv3 Control Message Header Over IP
98 *
99 * 0 1 2 3
100 * 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
101 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
102 * | (32 bits of zeros) |
103 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
104 * |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length |
105 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
106 * | Control Connection ID |
107 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
108 * | Ns | Nr |
109 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
110 *
111 * All control frames are passed to userspace.
112 */
113static int l2tp_ip_recv(struct sk_buff *skb)
114{
115 struct net *net = dev_net(skb->dev);
116 struct sock *sk;
117 u32 session_id;
118 u32 tunnel_id;
119 unsigned char *ptr, *optr;
120 struct l2tp_session *session;
121 struct l2tp_tunnel *tunnel = NULL;
122 struct iphdr *iph;
123
124 if (!pskb_may_pull(skb, 4))
125 goto discard;
126
127 /* Point to L2TP header */
128 optr = skb->data;
129 ptr = skb->data;
130 session_id = ntohl(*((__be32 *)ptr));
131 ptr += 4;
132
133 /* RFC3931: L2TP/IP packets have the first 4 bytes containing
134 * the session_id. If it is 0, the packet is a L2TP control
135 * frame and the session_id value can be discarded.
136 */
137 if (session_id == 0) {
138 __skb_pull(skb, 4);
139 goto pass_up;
140 }
141
142 /* Ok, this is a data packet. Lookup the session. */
143 session = l2tp_session_get(net, session_id);
144 if (!session)
145 goto discard;
146
147 tunnel = session->tunnel;
148 if (!tunnel)
149 goto discard_sess;
150
151 if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
152 goto discard_sess;
153
154 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
155 l2tp_session_dec_refcount(session);
156
157 return 0;
158
159pass_up:
160 /* Get the tunnel_id from the L2TP header */
161 if (!pskb_may_pull(skb, 12))
162 goto discard;
163
164 if ((skb->data[0] & 0xc0) != 0xc0)
165 goto discard;
166
167 tunnel_id = ntohl(*(__be32 *)&skb->data[4]);
168 iph = (struct iphdr *)skb_network_header(skb);
169
170 read_lock_bh(&l2tp_ip_lock);
171 sk = __l2tp_ip_bind_lookup(net, iph->daddr, iph->saddr, inet_iif(skb),
172 tunnel_id);
173 if (!sk) {
174 read_unlock_bh(&l2tp_ip_lock);
175 goto discard;
176 }
177 sock_hold(sk);
178 read_unlock_bh(&l2tp_ip_lock);
179
180 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
181 goto discard_put;
182
183 nf_reset_ct(skb);
184
185 return sk_receive_skb(sk, skb, 1);
186
187discard_sess:
188 l2tp_session_dec_refcount(session);
189 goto discard;
190
191discard_put:
192 sock_put(sk);
193
194discard:
195 kfree_skb(skb);
196 return 0;
197}
198
199static int l2tp_ip_hash(struct sock *sk)
200{
201 if (sk_unhashed(sk)) {
202 write_lock_bh(&l2tp_ip_lock);
203 sk_add_node(sk, &l2tp_ip_table);
204 write_unlock_bh(&l2tp_ip_lock);
205 }
206 return 0;
207}
208
209static void l2tp_ip_unhash(struct sock *sk)
210{
211 if (sk_unhashed(sk))
212 return;
213 write_lock_bh(&l2tp_ip_lock);
214 sk_del_node_init(sk);
215 write_unlock_bh(&l2tp_ip_lock);
216}
217
218static int l2tp_ip_open(struct sock *sk)
219{
220 /* Prevent autobind. We don't have ports. */
221 inet_sk(sk)->inet_num = IPPROTO_L2TP;
222
223 l2tp_ip_hash(sk);
224 return 0;
225}
226
227static void l2tp_ip_close(struct sock *sk, long timeout)
228{
229 write_lock_bh(&l2tp_ip_lock);
230 hlist_del_init(&sk->sk_bind_node);
231 sk_del_node_init(sk);
232 write_unlock_bh(&l2tp_ip_lock);
233 sk_common_release(sk);
234}
235
236static void l2tp_ip_destroy_sock(struct sock *sk)
237{
238 struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
239 struct sk_buff *skb;
240
241 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
242 kfree_skb(skb);
243
244 if (tunnel)
245 l2tp_tunnel_delete(tunnel);
246}
247
248static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
249{
250 struct inet_sock *inet = inet_sk(sk);
251 struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *)uaddr;
252 struct net *net = sock_net(sk);
253 int ret;
254 int chk_addr_ret;
255
256 if (addr_len < sizeof(struct sockaddr_l2tpip))
257 return -EINVAL;
258 if (addr->l2tp_family != AF_INET)
259 return -EINVAL;
260
261 lock_sock(sk);
262
263 ret = -EINVAL;
264 if (!sock_flag(sk, SOCK_ZAPPED))
265 goto out;
266
267 if (sk->sk_state != TCP_CLOSE)
268 goto out;
269
270 chk_addr_ret = inet_addr_type(net, addr->l2tp_addr.s_addr);
271 ret = -EADDRNOTAVAIL;
272 if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
273 chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
274 goto out;
275
276 if (addr->l2tp_addr.s_addr) {
277 inet->inet_rcv_saddr = addr->l2tp_addr.s_addr;
278 inet->inet_saddr = addr->l2tp_addr.s_addr;
279 }
280 if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
281 inet->inet_saddr = 0; /* Use device */
282
283 write_lock_bh(&l2tp_ip_lock);
284 if (__l2tp_ip_bind_lookup(net, addr->l2tp_addr.s_addr, 0,
285 sk->sk_bound_dev_if, addr->l2tp_conn_id)) {
286 write_unlock_bh(&l2tp_ip_lock);
287 ret = -EADDRINUSE;
288 goto out;
289 }
290
291 sk_dst_reset(sk);
292 l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
293
294 sk_add_bind_node(sk, &l2tp_ip_bind_table);
295 sk_del_node_init(sk);
296 write_unlock_bh(&l2tp_ip_lock);
297
298 ret = 0;
299 sock_reset_flag(sk, SOCK_ZAPPED);
300
301out:
302 release_sock(sk);
303
304 return ret;
305}
306
307static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
308{
309 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
310 int rc;
311
312 if (addr_len < sizeof(*lsa))
313 return -EINVAL;
314
315 if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
316 return -EINVAL;
317
318 lock_sock(sk);
319
320 /* Must bind first - autobinding does not work */
321 if (sock_flag(sk, SOCK_ZAPPED)) {
322 rc = -EINVAL;
323 goto out_sk;
324 }
325
326 rc = __ip4_datagram_connect(sk, uaddr, addr_len);
327 if (rc < 0)
328 goto out_sk;
329
330 l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
331
332 write_lock_bh(&l2tp_ip_lock);
333 hlist_del_init(&sk->sk_bind_node);
334 sk_add_bind_node(sk, &l2tp_ip_bind_table);
335 write_unlock_bh(&l2tp_ip_lock);
336
337out_sk:
338 release_sock(sk);
339
340 return rc;
341}
342
343static int l2tp_ip_disconnect(struct sock *sk, int flags)
344{
345 if (sock_flag(sk, SOCK_ZAPPED))
346 return 0;
347
348 return __udp_disconnect(sk, flags);
349}
350
351static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
352 int peer)
353{
354 struct sock *sk = sock->sk;
355 struct inet_sock *inet = inet_sk(sk);
356 struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
357 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
358
359 memset(lsa, 0, sizeof(*lsa));
360 lsa->l2tp_family = AF_INET;
361 if (peer) {
362 if (!inet->inet_dport)
363 return -ENOTCONN;
364 lsa->l2tp_conn_id = lsk->peer_conn_id;
365 lsa->l2tp_addr.s_addr = inet->inet_daddr;
366 } else {
367 __be32 addr = inet->inet_rcv_saddr;
368
369 if (!addr)
370 addr = inet->inet_saddr;
371 lsa->l2tp_conn_id = lsk->conn_id;
372 lsa->l2tp_addr.s_addr = addr;
373 }
374 return sizeof(*lsa);
375}
376
377static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
378{
379 int rc;
380
381 /* Charge it to the socket, dropping if the queue is full. */
382 rc = sock_queue_rcv_skb(sk, skb);
383 if (rc < 0)
384 goto drop;
385
386 return 0;
387
388drop:
389 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
390 kfree_skb(skb);
391 return 0;
392}
393
394/* Userspace will call sendmsg() on the tunnel socket to send L2TP
395 * control frames.
396 */
397static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
398{
399 struct sk_buff *skb;
400 int rc;
401 struct inet_sock *inet = inet_sk(sk);
402 struct rtable *rt = NULL;
403 struct flowi4 *fl4;
404 int connected = 0;
405 __be32 daddr;
406
407 lock_sock(sk);
408
409 rc = -ENOTCONN;
410 if (sock_flag(sk, SOCK_DEAD))
411 goto out;
412
413 /* Get and verify the address. */
414 if (msg->msg_name) {
415 DECLARE_SOCKADDR(struct sockaddr_l2tpip *, lip, msg->msg_name);
416
417 rc = -EINVAL;
418 if (msg->msg_namelen < sizeof(*lip))
419 goto out;
420
421 if (lip->l2tp_family != AF_INET) {
422 rc = -EAFNOSUPPORT;
423 if (lip->l2tp_family != AF_UNSPEC)
424 goto out;
425 }
426
427 daddr = lip->l2tp_addr.s_addr;
428 } else {
429 rc = -EDESTADDRREQ;
430 if (sk->sk_state != TCP_ESTABLISHED)
431 goto out;
432
433 daddr = inet->inet_daddr;
434 connected = 1;
435 }
436
437 /* Allocate a socket buffer */
438 rc = -ENOMEM;
439 skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
440 4 + len, 0, GFP_KERNEL);
441 if (!skb)
442 goto error;
443
444 /* Reserve space for headers, putting IP header on 4-byte boundary. */
445 skb_reserve(skb, 2 + NET_SKB_PAD);
446 skb_reset_network_header(skb);
447 skb_reserve(skb, sizeof(struct iphdr));
448 skb_reset_transport_header(skb);
449
450 /* Insert 0 session_id */
451 *((__be32 *)skb_put(skb, 4)) = 0;
452
453 /* Copy user data into skb */
454 rc = memcpy_from_msg(skb_put(skb, len), msg, len);
455 if (rc < 0) {
456 kfree_skb(skb);
457 goto error;
458 }
459
460 fl4 = &inet->cork.fl.u.ip4;
461 if (connected)
462 rt = (struct rtable *)__sk_dst_check(sk, 0);
463
464 rcu_read_lock();
465 if (!rt) {
466 const struct ip_options_rcu *inet_opt;
467
468 inet_opt = rcu_dereference(inet->inet_opt);
469
470 /* Use correct destination address if we have options. */
471 if (inet_opt && inet_opt->opt.srr)
472 daddr = inet_opt->opt.faddr;
473
474 /* If this fails, retransmit mechanism of transport layer will
475 * keep trying until route appears or the connection times
476 * itself out.
477 */
478 rt = ip_route_output_ports(sock_net(sk), fl4, sk,
479 daddr, inet->inet_saddr,
480 inet->inet_dport, inet->inet_sport,
481 sk->sk_protocol, RT_CONN_FLAGS(sk),
482 sk->sk_bound_dev_if);
483 if (IS_ERR(rt))
484 goto no_route;
485 if (connected) {
486 sk_setup_caps(sk, &rt->dst);
487 } else {
488 skb_dst_set(skb, &rt->dst);
489 goto xmit;
490 }
491 }
492
493 /* We don't need to clone dst here, it is guaranteed to not disappear.
494 * __dev_xmit_skb() might force a refcount if needed.
495 */
496 skb_dst_set_noref(skb, &rt->dst);
497
498xmit:
499 /* Queue the packet to IP for output */
500 rc = ip_queue_xmit(sk, skb, &inet->cork.fl);
501 rcu_read_unlock();
502
503error:
504 if (rc >= 0)
505 rc = len;
506
507out:
508 release_sock(sk);
509 return rc;
510
511no_route:
512 rcu_read_unlock();
513 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
514 kfree_skb(skb);
515 rc = -EHOSTUNREACH;
516 goto out;
517}
518
519static int l2tp_ip_recvmsg(struct sock *sk, struct msghdr *msg,
520 size_t len, int flags, int *addr_len)
521{
522 struct inet_sock *inet = inet_sk(sk);
523 size_t copied = 0;
524 int err = -EOPNOTSUPP;
525 DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
526 struct sk_buff *skb;
527
528 if (flags & MSG_OOB)
529 goto out;
530
531 skb = skb_recv_datagram(sk, flags, &err);
532 if (!skb)
533 goto out;
534
535 copied = skb->len;
536 if (len < copied) {
537 msg->msg_flags |= MSG_TRUNC;
538 copied = len;
539 }
540
541 err = skb_copy_datagram_msg(skb, 0, msg, copied);
542 if (err)
543 goto done;
544
545 sock_recv_timestamp(msg, sk, skb);
546
547 /* Copy the address. */
548 if (sin) {
549 sin->sin_family = AF_INET;
550 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
551 sin->sin_port = 0;
552 memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
553 *addr_len = sizeof(*sin);
554 }
555 if (inet_cmsg_flags(inet))
556 ip_cmsg_recv(msg, skb);
557 if (flags & MSG_TRUNC)
558 copied = skb->len;
559done:
560 skb_free_datagram(sk, skb);
561out:
562 return err ? err : copied;
563}
564
565int l2tp_ioctl(struct sock *sk, int cmd, int *karg)
566{
567 struct sk_buff *skb;
568
569 switch (cmd) {
570 case SIOCOUTQ:
571 *karg = sk_wmem_alloc_get(sk);
572 break;
573 case SIOCINQ:
574 spin_lock_bh(&sk->sk_receive_queue.lock);
575 skb = skb_peek(&sk->sk_receive_queue);
576 *karg = skb ? skb->len : 0;
577 spin_unlock_bh(&sk->sk_receive_queue.lock);
578 break;
579
580 default:
581 return -ENOIOCTLCMD;
582 }
583
584 return 0;
585}
586EXPORT_SYMBOL_GPL(l2tp_ioctl);
587
588static struct proto l2tp_ip_prot = {
589 .name = "L2TP/IP",
590 .owner = THIS_MODULE,
591 .init = l2tp_ip_open,
592 .close = l2tp_ip_close,
593 .bind = l2tp_ip_bind,
594 .connect = l2tp_ip_connect,
595 .disconnect = l2tp_ip_disconnect,
596 .ioctl = l2tp_ioctl,
597 .destroy = l2tp_ip_destroy_sock,
598 .setsockopt = ip_setsockopt,
599 .getsockopt = ip_getsockopt,
600 .sendmsg = l2tp_ip_sendmsg,
601 .recvmsg = l2tp_ip_recvmsg,
602 .backlog_rcv = l2tp_ip_backlog_recv,
603 .hash = l2tp_ip_hash,
604 .unhash = l2tp_ip_unhash,
605 .obj_size = sizeof(struct l2tp_ip_sock),
606};
607
608static const struct proto_ops l2tp_ip_ops = {
609 .family = PF_INET,
610 .owner = THIS_MODULE,
611 .release = inet_release,
612 .bind = inet_bind,
613 .connect = inet_dgram_connect,
614 .socketpair = sock_no_socketpair,
615 .accept = sock_no_accept,
616 .getname = l2tp_ip_getname,
617 .poll = datagram_poll,
618 .ioctl = inet_ioctl,
619 .gettstamp = sock_gettstamp,
620 .listen = sock_no_listen,
621 .shutdown = inet_shutdown,
622 .setsockopt = sock_common_setsockopt,
623 .getsockopt = sock_common_getsockopt,
624 .sendmsg = inet_sendmsg,
625 .recvmsg = sock_common_recvmsg,
626 .mmap = sock_no_mmap,
627};
628
629static struct inet_protosw l2tp_ip_protosw = {
630 .type = SOCK_DGRAM,
631 .protocol = IPPROTO_L2TP,
632 .prot = &l2tp_ip_prot,
633 .ops = &l2tp_ip_ops,
634};
635
636static struct net_protocol l2tp_ip_protocol __read_mostly = {
637 .handler = l2tp_ip_recv,
638};
639
640static int __init l2tp_ip_init(void)
641{
642 int err;
643
644 pr_info("L2TP IP encapsulation support (L2TPv3)\n");
645
646 err = proto_register(&l2tp_ip_prot, 1);
647 if (err != 0)
648 goto out;
649
650 err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
651 if (err)
652 goto out1;
653
654 inet_register_protosw(&l2tp_ip_protosw);
655 return 0;
656
657out1:
658 proto_unregister(&l2tp_ip_prot);
659out:
660 return err;
661}
662
663static void __exit l2tp_ip_exit(void)
664{
665 inet_unregister_protosw(&l2tp_ip_protosw);
666 inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
667 proto_unregister(&l2tp_ip_prot);
668}
669
670module_init(l2tp_ip_init);
671module_exit(l2tp_ip_exit);
672
673MODULE_LICENSE("GPL");
674MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
675MODULE_DESCRIPTION("L2TP over IP");
676MODULE_VERSION("1.0");
677
678/* Use the values of SOCK_DGRAM (2) as type and IPPROTO_L2TP (115) as protocol,
679 * because __stringify doesn't like enums
680 */
681MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 115, 2);
682MODULE_ALIAS_NET_PF_PROTO(PF_INET, 115);
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#include <linux/icmp.h>
13#include <linux/module.h>
14#include <linux/skbuff.h>
15#include <linux/random.h>
16#include <linux/socket.h>
17#include <linux/l2tp.h>
18#include <linux/in.h>
19#include <net/sock.h>
20#include <net/ip.h>
21#include <net/icmp.h>
22#include <net/udp.h>
23#include <net/inet_common.h>
24#include <net/inet_hashtables.h>
25#include <net/tcp_states.h>
26#include <net/protocol.h>
27#include <net/xfrm.h>
28
29#include "l2tp_core.h"
30
31struct l2tp_ip_sock {
32 /* inet_sock has to be the first member of l2tp_ip_sock */
33 struct inet_sock inet;
34
35 __u32 conn_id;
36 __u32 peer_conn_id;
37
38 __u64 tx_packets;
39 __u64 tx_bytes;
40 __u64 tx_errors;
41 __u64 rx_packets;
42 __u64 rx_bytes;
43 __u64 rx_errors;
44};
45
46static DEFINE_RWLOCK(l2tp_ip_lock);
47static struct hlist_head l2tp_ip_table;
48static struct hlist_head l2tp_ip_bind_table;
49
50static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
51{
52 return (struct l2tp_ip_sock *)sk;
53}
54
55static struct sock *__l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
56{
57 struct hlist_node *node;
58 struct sock *sk;
59
60 sk_for_each_bound(sk, node, &l2tp_ip_bind_table) {
61 struct inet_sock *inet = inet_sk(sk);
62 struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
63
64 if (l2tp == NULL)
65 continue;
66
67 if ((l2tp->conn_id == tunnel_id) &&
68 net_eq(sock_net(sk), net) &&
69 !(inet->inet_rcv_saddr && inet->inet_rcv_saddr != laddr) &&
70 !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif))
71 goto found;
72 }
73
74 sk = NULL;
75found:
76 return sk;
77}
78
79static inline struct sock *l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
80{
81 struct sock *sk = __l2tp_ip_bind_lookup(net, laddr, dif, tunnel_id);
82 if (sk)
83 sock_hold(sk);
84
85 return sk;
86}
87
88/* When processing receive frames, there are two cases to
89 * consider. Data frames consist of a non-zero session-id and an
90 * optional cookie. Control frames consist of a regular L2TP header
91 * preceded by 32-bits of zeros.
92 *
93 * L2TPv3 Session Header Over IP
94 *
95 * 0 1 2 3
96 * 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
97 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
98 * | Session ID |
99 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
100 * | Cookie (optional, maximum 64 bits)...
101 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
102 * |
103 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
104 *
105 * L2TPv3 Control Message Header Over IP
106 *
107 * 0 1 2 3
108 * 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
109 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
110 * | (32 bits of zeros) |
111 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
112 * |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length |
113 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
114 * | Control Connection ID |
115 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
116 * | Ns | Nr |
117 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
118 *
119 * All control frames are passed to userspace.
120 */
121static int l2tp_ip_recv(struct sk_buff *skb)
122{
123 struct sock *sk;
124 u32 session_id;
125 u32 tunnel_id;
126 unsigned char *ptr, *optr;
127 struct l2tp_session *session;
128 struct l2tp_tunnel *tunnel = NULL;
129 int length;
130 int offset;
131
132 /* Point to L2TP header */
133 optr = ptr = skb->data;
134
135 if (!pskb_may_pull(skb, 4))
136 goto discard;
137
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_find(&init_net, NULL, session_id);
152 if (session == NULL)
153 goto discard;
154
155 tunnel = session->tunnel;
156 if (tunnel == NULL)
157 goto discard;
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;
164
165 printk(KERN_DEBUG "%s: ip recv: ", tunnel->name);
166
167 offset = 0;
168 do {
169 printk(" %02X", ptr[offset]);
170 } while (++offset < length);
171
172 printk("\n");
173 }
174
175 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook);
176
177 return 0;
178
179pass_up:
180 /* Get the tunnel_id from the L2TP header */
181 if (!pskb_may_pull(skb, 12))
182 goto discard;
183
184 if ((skb->data[0] & 0xc0) != 0xc0)
185 goto discard;
186
187 tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
188 tunnel = l2tp_tunnel_find(&init_net, tunnel_id);
189 if (tunnel != NULL)
190 sk = tunnel->sock;
191 else {
192 struct iphdr *iph = (struct iphdr *) skb_network_header(skb);
193
194 read_lock_bh(&l2tp_ip_lock);
195 sk = __l2tp_ip_bind_lookup(&init_net, iph->daddr, 0, tunnel_id);
196 read_unlock_bh(&l2tp_ip_lock);
197 }
198
199 if (sk == NULL)
200 goto discard;
201
202 sock_hold(sk);
203
204 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
205 goto discard_put;
206
207 nf_reset(skb);
208
209 return sk_receive_skb(sk, skb, 1);
210
211discard_put:
212 sock_put(sk);
213
214discard:
215 kfree_skb(skb);
216 return 0;
217}
218
219static int l2tp_ip_open(struct sock *sk)
220{
221 /* Prevent autobind. We don't have ports. */
222 inet_sk(sk)->inet_num = IPPROTO_L2TP;
223
224 write_lock_bh(&l2tp_ip_lock);
225 sk_add_node(sk, &l2tp_ip_table);
226 write_unlock_bh(&l2tp_ip_lock);
227
228 return 0;
229}
230
231static void l2tp_ip_close(struct sock *sk, long timeout)
232{
233 write_lock_bh(&l2tp_ip_lock);
234 hlist_del_init(&sk->sk_bind_node);
235 hlist_del_init(&sk->sk_node);
236 write_unlock_bh(&l2tp_ip_lock);
237 sk_common_release(sk);
238}
239
240static void l2tp_ip_destroy_sock(struct sock *sk)
241{
242 struct sk_buff *skb;
243
244 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
245 kfree_skb(skb);
246
247 sk_refcnt_debug_dec(sk);
248}
249
250static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
251{
252 struct inet_sock *inet = inet_sk(sk);
253 struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
254 int ret = -EINVAL;
255 int chk_addr_ret;
256
257 ret = -EADDRINUSE;
258 read_lock_bh(&l2tp_ip_lock);
259 if (__l2tp_ip_bind_lookup(&init_net, addr->l2tp_addr.s_addr, sk->sk_bound_dev_if, addr->l2tp_conn_id))
260 goto out_in_use;
261
262 read_unlock_bh(&l2tp_ip_lock);
263
264 lock_sock(sk);
265 if (sk->sk_state != TCP_CLOSE || addr_len < sizeof(struct sockaddr_l2tpip))
266 goto out;
267
268 chk_addr_ret = inet_addr_type(&init_net, addr->l2tp_addr.s_addr);
269 ret = -EADDRNOTAVAIL;
270 if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
271 chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
272 goto out;
273
274 inet->inet_rcv_saddr = inet->inet_saddr = addr->l2tp_addr.s_addr;
275 if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
276 inet->inet_saddr = 0; /* Use device */
277 sk_dst_reset(sk);
278
279 l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
280
281 write_lock_bh(&l2tp_ip_lock);
282 sk_add_bind_node(sk, &l2tp_ip_bind_table);
283 sk_del_node_init(sk);
284 write_unlock_bh(&l2tp_ip_lock);
285 ret = 0;
286out:
287 release_sock(sk);
288
289 return ret;
290
291out_in_use:
292 read_unlock_bh(&l2tp_ip_lock);
293
294 return ret;
295}
296
297static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
298{
299 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
300 struct inet_sock *inet = inet_sk(sk);
301 struct flowi4 *fl4;
302 struct rtable *rt;
303 __be32 saddr;
304 int oif, rc;
305
306 rc = -EINVAL;
307 if (addr_len < sizeof(*lsa))
308 goto out;
309
310 rc = -EAFNOSUPPORT;
311 if (lsa->l2tp_family != AF_INET)
312 goto out;
313
314 lock_sock(sk);
315
316 sk_dst_reset(sk);
317
318 oif = sk->sk_bound_dev_if;
319 saddr = inet->inet_saddr;
320
321 rc = -EINVAL;
322 if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
323 goto out;
324
325 fl4 = &inet->cork.fl.u.ip4;
326 rt = ip_route_connect(fl4, lsa->l2tp_addr.s_addr, saddr,
327 RT_CONN_FLAGS(sk), oif,
328 IPPROTO_L2TP,
329 0, 0, sk, true);
330 if (IS_ERR(rt)) {
331 rc = PTR_ERR(rt);
332 if (rc == -ENETUNREACH)
333 IP_INC_STATS_BH(&init_net, IPSTATS_MIB_OUTNOROUTES);
334 goto out;
335 }
336
337 rc = -ENETUNREACH;
338 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
339 ip_rt_put(rt);
340 goto out;
341 }
342
343 l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
344
345 if (!inet->inet_saddr)
346 inet->inet_saddr = fl4->saddr;
347 if (!inet->inet_rcv_saddr)
348 inet->inet_rcv_saddr = fl4->saddr;
349 inet->inet_daddr = fl4->daddr;
350 sk->sk_state = TCP_ESTABLISHED;
351 inet->inet_id = jiffies;
352
353 sk_dst_set(sk, &rt->dst);
354
355 write_lock_bh(&l2tp_ip_lock);
356 hlist_del_init(&sk->sk_bind_node);
357 sk_add_bind_node(sk, &l2tp_ip_bind_table);
358 write_unlock_bh(&l2tp_ip_lock);
359
360 rc = 0;
361out:
362 release_sock(sk);
363 return rc;
364}
365
366static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
367 int *uaddr_len, int peer)
368{
369 struct sock *sk = sock->sk;
370 struct inet_sock *inet = inet_sk(sk);
371 struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
372 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
373
374 memset(lsa, 0, sizeof(*lsa));
375 lsa->l2tp_family = AF_INET;
376 if (peer) {
377 if (!inet->inet_dport)
378 return -ENOTCONN;
379 lsa->l2tp_conn_id = lsk->peer_conn_id;
380 lsa->l2tp_addr.s_addr = inet->inet_daddr;
381 } else {
382 __be32 addr = inet->inet_rcv_saddr;
383 if (!addr)
384 addr = inet->inet_saddr;
385 lsa->l2tp_conn_id = lsk->conn_id;
386 lsa->l2tp_addr.s_addr = addr;
387 }
388 *uaddr_len = sizeof(*lsa);
389 return 0;
390}
391
392static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
393{
394 int rc;
395
396 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
397 goto drop;
398
399 nf_reset(skb);
400
401 /* Charge it to the socket, dropping if the queue is full. */
402 rc = sock_queue_rcv_skb(sk, skb);
403 if (rc < 0)
404 goto drop;
405
406 return 0;
407
408drop:
409 IP_INC_STATS(&init_net, IPSTATS_MIB_INDISCARDS);
410 kfree_skb(skb);
411 return -1;
412}
413
414/* Userspace will call sendmsg() on the tunnel socket to send L2TP
415 * control frames.
416 */
417static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len)
418{
419 struct sk_buff *skb;
420 int rc;
421 struct l2tp_ip_sock *lsa = l2tp_ip_sk(sk);
422 struct inet_sock *inet = inet_sk(sk);
423 struct rtable *rt = NULL;
424 struct flowi4 *fl4;
425 int connected = 0;
426 __be32 daddr;
427
428 lock_sock(sk);
429
430 rc = -ENOTCONN;
431 if (sock_flag(sk, SOCK_DEAD))
432 goto out;
433
434 /* Get and verify the address. */
435 if (msg->msg_name) {
436 struct sockaddr_l2tpip *lip = (struct sockaddr_l2tpip *) msg->msg_name;
437 rc = -EINVAL;
438 if (msg->msg_namelen < sizeof(*lip))
439 goto out;
440
441 if (lip->l2tp_family != AF_INET) {
442 rc = -EAFNOSUPPORT;
443 if (lip->l2tp_family != AF_UNSPEC)
444 goto out;
445 }
446
447 daddr = lip->l2tp_addr.s_addr;
448 } else {
449 if (sk->sk_state != TCP_ESTABLISHED)
450 return -EDESTADDRREQ;
451
452 daddr = inet->inet_daddr;
453 connected = 1;
454 }
455
456 /* Allocate a socket buffer */
457 rc = -ENOMEM;
458 skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
459 4 + len, 0, GFP_KERNEL);
460 if (!skb)
461 goto error;
462
463 /* Reserve space for headers, putting IP header on 4-byte boundary. */
464 skb_reserve(skb, 2 + NET_SKB_PAD);
465 skb_reset_network_header(skb);
466 skb_reserve(skb, sizeof(struct iphdr));
467 skb_reset_transport_header(skb);
468
469 /* Insert 0 session_id */
470 *((__be32 *) skb_put(skb, 4)) = 0;
471
472 /* Copy user data into skb */
473 rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
474 if (rc < 0) {
475 kfree_skb(skb);
476 goto error;
477 }
478
479 fl4 = &inet->cork.fl.u.ip4;
480 if (connected)
481 rt = (struct rtable *) __sk_dst_check(sk, 0);
482
483 rcu_read_lock();
484 if (rt == NULL) {
485 const struct ip_options_rcu *inet_opt;
486
487 inet_opt = rcu_dereference(inet->inet_opt);
488
489 /* Use correct destination address if we have options. */
490 if (inet_opt && inet_opt->opt.srr)
491 daddr = inet_opt->opt.faddr;
492
493 /* If this fails, retransmit mechanism of transport layer will
494 * keep trying until route appears or the connection times
495 * itself out.
496 */
497 rt = ip_route_output_ports(sock_net(sk), fl4, sk,
498 daddr, inet->inet_saddr,
499 inet->inet_dport, inet->inet_sport,
500 sk->sk_protocol, RT_CONN_FLAGS(sk),
501 sk->sk_bound_dev_if);
502 if (IS_ERR(rt))
503 goto no_route;
504 if (connected)
505 sk_setup_caps(sk, &rt->dst);
506 else
507 dst_release(&rt->dst); /* safe since we hold rcu_read_lock */
508 }
509
510 /* We dont need to clone dst here, it is guaranteed to not disappear.
511 * __dev_xmit_skb() might force a refcount if needed.
512 */
513 skb_dst_set_noref(skb, &rt->dst);
514
515 /* Queue the packet to IP for output */
516 rc = ip_queue_xmit(skb, &inet->cork.fl);
517 rcu_read_unlock();
518
519error:
520 /* Update stats */
521 if (rc >= 0) {
522 lsa->tx_packets++;
523 lsa->tx_bytes += len;
524 rc = len;
525 } else {
526 lsa->tx_errors++;
527 }
528
529out:
530 release_sock(sk);
531 return rc;
532
533no_route:
534 rcu_read_unlock();
535 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
536 kfree_skb(skb);
537 rc = -EHOSTUNREACH;
538 goto out;
539}
540
541static int l2tp_ip_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
542 size_t len, int noblock, int flags, int *addr_len)
543{
544 struct inet_sock *inet = inet_sk(sk);
545 struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
546 size_t copied = 0;
547 int err = -EOPNOTSUPP;
548 struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
549 struct sk_buff *skb;
550
551 if (flags & MSG_OOB)
552 goto out;
553
554 if (addr_len)
555 *addr_len = sizeof(*sin);
556
557 skb = skb_recv_datagram(sk, flags, noblock, &err);
558 if (!skb)
559 goto out;
560
561 copied = skb->len;
562 if (len < copied) {
563 msg->msg_flags |= MSG_TRUNC;
564 copied = len;
565 }
566
567 err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
568 if (err)
569 goto done;
570
571 sock_recv_timestamp(msg, sk, skb);
572
573 /* Copy the address. */
574 if (sin) {
575 sin->sin_family = AF_INET;
576 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
577 sin->sin_port = 0;
578 memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
579 }
580 if (inet->cmsg_flags)
581 ip_cmsg_recv(msg, skb);
582 if (flags & MSG_TRUNC)
583 copied = skb->len;
584done:
585 skb_free_datagram(sk, skb);
586out:
587 if (err) {
588 lsk->rx_errors++;
589 return err;
590 }
591
592 lsk->rx_packets++;
593 lsk->rx_bytes += copied;
594
595 return copied;
596}
597
598static struct proto l2tp_ip_prot = {
599 .name = "L2TP/IP",
600 .owner = THIS_MODULE,
601 .init = l2tp_ip_open,
602 .close = l2tp_ip_close,
603 .bind = l2tp_ip_bind,
604 .connect = l2tp_ip_connect,
605 .disconnect = udp_disconnect,
606 .ioctl = udp_ioctl,
607 .destroy = l2tp_ip_destroy_sock,
608 .setsockopt = ip_setsockopt,
609 .getsockopt = ip_getsockopt,
610 .sendmsg = l2tp_ip_sendmsg,
611 .recvmsg = l2tp_ip_recvmsg,
612 .backlog_rcv = l2tp_ip_backlog_recv,
613 .hash = inet_hash,
614 .unhash = inet_unhash,
615 .obj_size = sizeof(struct l2tp_ip_sock),
616#ifdef CONFIG_COMPAT
617 .compat_setsockopt = compat_ip_setsockopt,
618 .compat_getsockopt = compat_ip_getsockopt,
619#endif
620};
621
622static const struct proto_ops l2tp_ip_ops = {
623 .family = PF_INET,
624 .owner = THIS_MODULE,
625 .release = inet_release,
626 .bind = inet_bind,
627 .connect = inet_dgram_connect,
628 .socketpair = sock_no_socketpair,
629 .accept = sock_no_accept,
630 .getname = l2tp_ip_getname,
631 .poll = datagram_poll,
632 .ioctl = inet_ioctl,
633 .listen = sock_no_listen,
634 .shutdown = inet_shutdown,
635 .setsockopt = sock_common_setsockopt,
636 .getsockopt = sock_common_getsockopt,
637 .sendmsg = inet_sendmsg,
638 .recvmsg = sock_common_recvmsg,
639 .mmap = sock_no_mmap,
640 .sendpage = sock_no_sendpage,
641#ifdef CONFIG_COMPAT
642 .compat_setsockopt = compat_sock_common_setsockopt,
643 .compat_getsockopt = compat_sock_common_getsockopt,
644#endif
645};
646
647static struct inet_protosw l2tp_ip_protosw = {
648 .type = SOCK_DGRAM,
649 .protocol = IPPROTO_L2TP,
650 .prot = &l2tp_ip_prot,
651 .ops = &l2tp_ip_ops,
652 .no_check = 0,
653};
654
655static struct net_protocol l2tp_ip_protocol __read_mostly = {
656 .handler = l2tp_ip_recv,
657};
658
659static int __init l2tp_ip_init(void)
660{
661 int err;
662
663 printk(KERN_INFO "L2TP IP encapsulation support (L2TPv3)\n");
664
665 err = proto_register(&l2tp_ip_prot, 1);
666 if (err != 0)
667 goto out;
668
669 err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
670 if (err)
671 goto out1;
672
673 inet_register_protosw(&l2tp_ip_protosw);
674 return 0;
675
676out1:
677 proto_unregister(&l2tp_ip_prot);
678out:
679 return err;
680}
681
682static void __exit l2tp_ip_exit(void)
683{
684 inet_unregister_protosw(&l2tp_ip_protosw);
685 inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
686 proto_unregister(&l2tp_ip_prot);
687}
688
689module_init(l2tp_ip_init);
690module_exit(l2tp_ip_exit);
691
692MODULE_LICENSE("GPL");
693MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
694MODULE_DESCRIPTION("L2TP over IP");
695MODULE_VERSION("1.0");
696
697/* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
698 * enums
699 */
700MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP);