xref: /openbmc/linux/net/l2tp/l2tp_ip.c (revision ae3473231e77a3f1909d48cd144cebe5e1d049b3)
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 || !dif ||
65 		     sk->sk_bound_dev_if == dif))
66 			goto found;
67 	}
68 
69 	sk = NULL;
70 found:
71 	return sk;
72 }
73 
74 static inline struct sock *l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
75 {
76 	struct sock *sk = __l2tp_ip_bind_lookup(net, laddr, dif, tunnel_id);
77 	if (sk)
78 		sock_hold(sk);
79 
80 	return sk;
81 }
82 
83 /* When processing receive frames, there are two cases to
84  * consider. Data frames consist of a non-zero session-id and an
85  * optional cookie. Control frames consist of a regular L2TP header
86  * preceded by 32-bits of zeros.
87  *
88  * L2TPv3 Session Header Over IP
89  *
90  *  0                   1                   2                   3
91  *  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
92  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
93  * |                           Session ID                          |
94  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
95  * |               Cookie (optional, maximum 64 bits)...
96  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
97  *                                                                 |
98  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
99  *
100  * L2TPv3 Control Message Header Over IP
101  *
102  *  0                   1                   2                   3
103  *  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
104  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
105  * |                      (32 bits of zeros)                       |
106  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
107  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
108  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
109  * |                     Control Connection ID                     |
110  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
111  * |               Ns              |               Nr              |
112  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
113  *
114  * All control frames are passed to userspace.
115  */
116 static int l2tp_ip_recv(struct sk_buff *skb)
117 {
118 	struct net *net = dev_net(skb->dev);
119 	struct sock *sk;
120 	u32 session_id;
121 	u32 tunnel_id;
122 	unsigned char *ptr, *optr;
123 	struct l2tp_session *session;
124 	struct l2tp_tunnel *tunnel = NULL;
125 	int length;
126 
127 	if (!pskb_may_pull(skb, 4))
128 		goto discard;
129 
130 	/* Point to L2TP header */
131 	optr = ptr = skb->data;
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 		/* Point to L2TP header */
160 		optr = ptr = skb->data;
161 		ptr += 4;
162 		pr_debug("%s: ip recv\n", tunnel->name);
163 		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
164 	}
165 
166 	l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook);
167 
168 	return 0;
169 
170 pass_up:
171 	/* Get the tunnel_id from the L2TP header */
172 	if (!pskb_may_pull(skb, 12))
173 		goto discard;
174 
175 	if ((skb->data[0] & 0xc0) != 0xc0)
176 		goto discard;
177 
178 	tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
179 	tunnel = l2tp_tunnel_find(net, tunnel_id);
180 	if (tunnel != NULL)
181 		sk = tunnel->sock;
182 	else {
183 		struct iphdr *iph = (struct iphdr *) skb_network_header(skb);
184 
185 		read_lock_bh(&l2tp_ip_lock);
186 		sk = __l2tp_ip_bind_lookup(net, iph->daddr, inet_iif(skb),
187 					   tunnel_id);
188 		if (!sk) {
189 			read_unlock_bh(&l2tp_ip_lock);
190 			goto discard;
191 		}
192 
193 		sock_hold(sk);
194 		read_unlock_bh(&l2tp_ip_lock);
195 	}
196 
197 	if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
198 		goto discard_put;
199 
200 	nf_reset(skb);
201 
202 	return sk_receive_skb(sk, skb, 1);
203 
204 discard_put:
205 	sock_put(sk);
206 
207 discard:
208 	kfree_skb(skb);
209 	return 0;
210 }
211 
212 static int l2tp_ip_open(struct sock *sk)
213 {
214 	/* Prevent autobind. We don't have ports. */
215 	inet_sk(sk)->inet_num = IPPROTO_L2TP;
216 
217 	write_lock_bh(&l2tp_ip_lock);
218 	sk_add_node(sk, &l2tp_ip_table);
219 	write_unlock_bh(&l2tp_ip_lock);
220 
221 	return 0;
222 }
223 
224 static void l2tp_ip_close(struct sock *sk, long timeout)
225 {
226 	write_lock_bh(&l2tp_ip_lock);
227 	hlist_del_init(&sk->sk_bind_node);
228 	sk_del_node_init(sk);
229 	write_unlock_bh(&l2tp_ip_lock);
230 	sk_common_release(sk);
231 }
232 
233 static void l2tp_ip_destroy_sock(struct sock *sk)
234 {
235 	struct sk_buff *skb;
236 	struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
237 
238 	while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
239 		kfree_skb(skb);
240 
241 	if (tunnel) {
242 		l2tp_tunnel_closeall(tunnel);
243 		sock_put(sk);
244 	}
245 
246 	sk_refcnt_debug_dec(sk);
247 }
248 
249 static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
250 {
251 	struct inet_sock *inet = inet_sk(sk);
252 	struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
253 	struct net *net = sock_net(sk);
254 	int ret;
255 	int chk_addr_ret;
256 
257 	if (addr_len < sizeof(struct sockaddr_l2tpip))
258 		return -EINVAL;
259 	if (addr->l2tp_family != AF_INET)
260 		return -EINVAL;
261 
262 	lock_sock(sk);
263 
264 	ret = -EINVAL;
265 	if (!sock_flag(sk, SOCK_ZAPPED))
266 		goto out;
267 
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 
282 	write_lock_bh(&l2tp_ip_lock);
283 	if (__l2tp_ip_bind_lookup(net, addr->l2tp_addr.s_addr,
284 				  sk->sk_bound_dev_if, addr->l2tp_conn_id)) {
285 		write_unlock_bh(&l2tp_ip_lock);
286 		ret = -EADDRINUSE;
287 		goto out;
288 	}
289 
290 	sk_dst_reset(sk);
291 	l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
292 
293 	sk_add_bind_node(sk, &l2tp_ip_bind_table);
294 	sk_del_node_init(sk);
295 	write_unlock_bh(&l2tp_ip_lock);
296 
297 	ret = 0;
298 	sock_reset_flag(sk, SOCK_ZAPPED);
299 
300 out:
301 	release_sock(sk);
302 
303 	return ret;
304 }
305 
306 static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
307 {
308 	struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
309 	int rc;
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 	lock_sock(sk);
318 
319 	/* Must bind first - autobinding does not work */
320 	if (sock_flag(sk, SOCK_ZAPPED)) {
321 		rc = -EINVAL;
322 		goto out_sk;
323 	}
324 
325 	rc = __ip4_datagram_connect(sk, uaddr, addr_len);
326 	if (rc < 0)
327 		goto out_sk;
328 
329 	l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
330 
331 	write_lock_bh(&l2tp_ip_lock);
332 	hlist_del_init(&sk->sk_bind_node);
333 	sk_add_bind_node(sk, &l2tp_ip_bind_table);
334 	write_unlock_bh(&l2tp_ip_lock);
335 
336 out_sk:
337 	release_sock(sk);
338 
339 	return rc;
340 }
341 
342 static int l2tp_ip_disconnect(struct sock *sk, int flags)
343 {
344 	if (sock_flag(sk, SOCK_ZAPPED))
345 		return 0;
346 
347 	return __udp_disconnect(sk, flags);
348 }
349 
350 static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
351 			   int *uaddr_len, int peer)
352 {
353 	struct sock *sk		= sock->sk;
354 	struct inet_sock *inet	= inet_sk(sk);
355 	struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
356 	struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
357 
358 	memset(lsa, 0, sizeof(*lsa));
359 	lsa->l2tp_family = AF_INET;
360 	if (peer) {
361 		if (!inet->inet_dport)
362 			return -ENOTCONN;
363 		lsa->l2tp_conn_id = lsk->peer_conn_id;
364 		lsa->l2tp_addr.s_addr = inet->inet_daddr;
365 	} else {
366 		__be32 addr = inet->inet_rcv_saddr;
367 		if (!addr)
368 			addr = inet->inet_saddr;
369 		lsa->l2tp_conn_id = lsk->conn_id;
370 		lsa->l2tp_addr.s_addr = addr;
371 	}
372 	*uaddr_len = sizeof(*lsa);
373 	return 0;
374 }
375 
376 static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
377 {
378 	int rc;
379 
380 	/* Charge it to the socket, dropping if the queue is full. */
381 	rc = sock_queue_rcv_skb(sk, skb);
382 	if (rc < 0)
383 		goto drop;
384 
385 	return 0;
386 
387 drop:
388 	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
389 	kfree_skb(skb);
390 	return -1;
391 }
392 
393 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
394  * control frames.
395  */
396 static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
397 {
398 	struct sk_buff *skb;
399 	int rc;
400 	struct inet_sock *inet = inet_sk(sk);
401 	struct rtable *rt = NULL;
402 	struct flowi4 *fl4;
403 	int connected = 0;
404 	__be32 daddr;
405 
406 	lock_sock(sk);
407 
408 	rc = -ENOTCONN;
409 	if (sock_flag(sk, SOCK_DEAD))
410 		goto out;
411 
412 	/* Get and verify the address. */
413 	if (msg->msg_name) {
414 		DECLARE_SOCKADDR(struct sockaddr_l2tpip *, lip, msg->msg_name);
415 		rc = -EINVAL;
416 		if (msg->msg_namelen < sizeof(*lip))
417 			goto out;
418 
419 		if (lip->l2tp_family != AF_INET) {
420 			rc = -EAFNOSUPPORT;
421 			if (lip->l2tp_family != AF_UNSPEC)
422 				goto out;
423 		}
424 
425 		daddr = lip->l2tp_addr.s_addr;
426 	} else {
427 		rc = -EDESTADDRREQ;
428 		if (sk->sk_state != TCP_ESTABLISHED)
429 			goto out;
430 
431 		daddr = inet->inet_daddr;
432 		connected = 1;
433 	}
434 
435 	/* Allocate a socket buffer */
436 	rc = -ENOMEM;
437 	skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
438 			   4 + len, 0, GFP_KERNEL);
439 	if (!skb)
440 		goto error;
441 
442 	/* Reserve space for headers, putting IP header on 4-byte boundary. */
443 	skb_reserve(skb, 2 + NET_SKB_PAD);
444 	skb_reset_network_header(skb);
445 	skb_reserve(skb, sizeof(struct iphdr));
446 	skb_reset_transport_header(skb);
447 
448 	/* Insert 0 session_id */
449 	*((__be32 *) skb_put(skb, 4)) = 0;
450 
451 	/* Copy user data into skb */
452 	rc = memcpy_from_msg(skb_put(skb, len), msg, len);
453 	if (rc < 0) {
454 		kfree_skb(skb);
455 		goto error;
456 	}
457 
458 	fl4 = &inet->cork.fl.u.ip4;
459 	if (connected)
460 		rt = (struct rtable *) __sk_dst_check(sk, 0);
461 
462 	rcu_read_lock();
463 	if (rt == NULL) {
464 		const struct ip_options_rcu *inet_opt;
465 
466 		inet_opt = rcu_dereference(inet->inet_opt);
467 
468 		/* Use correct destination address if we have options. */
469 		if (inet_opt && inet_opt->opt.srr)
470 			daddr = inet_opt->opt.faddr;
471 
472 		/* If this fails, retransmit mechanism of transport layer will
473 		 * keep trying until route appears or the connection times
474 		 * itself out.
475 		 */
476 		rt = ip_route_output_ports(sock_net(sk), fl4, sk,
477 					   daddr, inet->inet_saddr,
478 					   inet->inet_dport, inet->inet_sport,
479 					   sk->sk_protocol, RT_CONN_FLAGS(sk),
480 					   sk->sk_bound_dev_if);
481 		if (IS_ERR(rt))
482 			goto no_route;
483 		if (connected) {
484 			sk_setup_caps(sk, &rt->dst);
485 		} else {
486 			skb_dst_set(skb, &rt->dst);
487 			goto xmit;
488 		}
489 	}
490 
491 	/* We dont need to clone dst here, it is guaranteed to not disappear.
492 	 *  __dev_xmit_skb() might force a refcount if needed.
493 	 */
494 	skb_dst_set_noref(skb, &rt->dst);
495 
496 xmit:
497 	/* Queue the packet to IP for output */
498 	rc = ip_queue_xmit(sk, skb, &inet->cork.fl);
499 	rcu_read_unlock();
500 
501 error:
502 	if (rc >= 0)
503 		rc = len;
504 
505 out:
506 	release_sock(sk);
507 	return rc;
508 
509 no_route:
510 	rcu_read_unlock();
511 	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
512 	kfree_skb(skb);
513 	rc = -EHOSTUNREACH;
514 	goto out;
515 }
516 
517 static int l2tp_ip_recvmsg(struct sock *sk, struct msghdr *msg,
518 			   size_t len, int noblock, int flags, int *addr_len)
519 {
520 	struct inet_sock *inet = inet_sk(sk);
521 	size_t copied = 0;
522 	int err = -EOPNOTSUPP;
523 	DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
524 	struct sk_buff *skb;
525 
526 	if (flags & MSG_OOB)
527 		goto out;
528 
529 	skb = skb_recv_datagram(sk, flags, noblock, &err);
530 	if (!skb)
531 		goto out;
532 
533 	copied = skb->len;
534 	if (len < copied) {
535 		msg->msg_flags |= MSG_TRUNC;
536 		copied = len;
537 	}
538 
539 	err = skb_copy_datagram_msg(skb, 0, msg, copied);
540 	if (err)
541 		goto done;
542 
543 	sock_recv_timestamp(msg, sk, skb);
544 
545 	/* Copy the address. */
546 	if (sin) {
547 		sin->sin_family = AF_INET;
548 		sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
549 		sin->sin_port = 0;
550 		memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
551 		*addr_len = sizeof(*sin);
552 	}
553 	if (inet->cmsg_flags)
554 		ip_cmsg_recv(msg, skb);
555 	if (flags & MSG_TRUNC)
556 		copied = skb->len;
557 done:
558 	skb_free_datagram(sk, skb);
559 out:
560 	return err ? err : copied;
561 }
562 
563 static struct proto l2tp_ip_prot = {
564 	.name		   = "L2TP/IP",
565 	.owner		   = THIS_MODULE,
566 	.init		   = l2tp_ip_open,
567 	.close		   = l2tp_ip_close,
568 	.bind		   = l2tp_ip_bind,
569 	.connect	   = l2tp_ip_connect,
570 	.disconnect	   = l2tp_ip_disconnect,
571 	.ioctl		   = udp_ioctl,
572 	.destroy	   = l2tp_ip_destroy_sock,
573 	.setsockopt	   = ip_setsockopt,
574 	.getsockopt	   = ip_getsockopt,
575 	.sendmsg	   = l2tp_ip_sendmsg,
576 	.recvmsg	   = l2tp_ip_recvmsg,
577 	.backlog_rcv	   = l2tp_ip_backlog_recv,
578 	.hash		   = inet_hash,
579 	.unhash		   = inet_unhash,
580 	.obj_size	   = sizeof(struct l2tp_ip_sock),
581 #ifdef CONFIG_COMPAT
582 	.compat_setsockopt = compat_ip_setsockopt,
583 	.compat_getsockopt = compat_ip_getsockopt,
584 #endif
585 };
586 
587 static const struct proto_ops l2tp_ip_ops = {
588 	.family		   = PF_INET,
589 	.owner		   = THIS_MODULE,
590 	.release	   = inet_release,
591 	.bind		   = inet_bind,
592 	.connect	   = inet_dgram_connect,
593 	.socketpair	   = sock_no_socketpair,
594 	.accept		   = sock_no_accept,
595 	.getname	   = l2tp_ip_getname,
596 	.poll		   = datagram_poll,
597 	.ioctl		   = inet_ioctl,
598 	.listen		   = sock_no_listen,
599 	.shutdown	   = inet_shutdown,
600 	.setsockopt	   = sock_common_setsockopt,
601 	.getsockopt	   = sock_common_getsockopt,
602 	.sendmsg	   = inet_sendmsg,
603 	.recvmsg	   = sock_common_recvmsg,
604 	.mmap		   = sock_no_mmap,
605 	.sendpage	   = sock_no_sendpage,
606 #ifdef CONFIG_COMPAT
607 	.compat_setsockopt = compat_sock_common_setsockopt,
608 	.compat_getsockopt = compat_sock_common_getsockopt,
609 #endif
610 };
611 
612 static struct inet_protosw l2tp_ip_protosw = {
613 	.type		= SOCK_DGRAM,
614 	.protocol	= IPPROTO_L2TP,
615 	.prot		= &l2tp_ip_prot,
616 	.ops		= &l2tp_ip_ops,
617 };
618 
619 static struct net_protocol l2tp_ip_protocol __read_mostly = {
620 	.handler	= l2tp_ip_recv,
621 	.netns_ok	= 1,
622 };
623 
624 static int __init l2tp_ip_init(void)
625 {
626 	int err;
627 
628 	pr_info("L2TP IP encapsulation support (L2TPv3)\n");
629 
630 	err = proto_register(&l2tp_ip_prot, 1);
631 	if (err != 0)
632 		goto out;
633 
634 	err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
635 	if (err)
636 		goto out1;
637 
638 	inet_register_protosw(&l2tp_ip_protosw);
639 	return 0;
640 
641 out1:
642 	proto_unregister(&l2tp_ip_prot);
643 out:
644 	return err;
645 }
646 
647 static void __exit l2tp_ip_exit(void)
648 {
649 	inet_unregister_protosw(&l2tp_ip_protosw);
650 	inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
651 	proto_unregister(&l2tp_ip_prot);
652 }
653 
654 module_init(l2tp_ip_init);
655 module_exit(l2tp_ip_exit);
656 
657 MODULE_LICENSE("GPL");
658 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
659 MODULE_DESCRIPTION("L2TP over IP");
660 MODULE_VERSION("1.0");
661 
662 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
663  * enums
664  */
665 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP);
666 MODULE_ALIAS_NET_PF_PROTO(PF_INET, IPPROTO_L2TP);
667