xref: /openbmc/linux/net/l2tp/l2tp_ip.c (revision 82df5b73) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * L2TPv3 IP encapsulation support
4  *
5  * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
6  */
7 
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 
10 #include <asm/ioctls.h>
11 #include <linux/icmp.h>
12 #include <linux/module.h>
13 #include <linux/skbuff.h>
14 #include <linux/random.h>
15 #include <linux/socket.h>
16 #include <linux/l2tp.h>
17 #include <linux/in.h>
18 #include <net/sock.h>
19 #include <net/ip.h>
20 #include <net/icmp.h>
21 #include <net/udp.h>
22 #include <net/inet_common.h>
23 #include <net/tcp_states.h>
24 #include <net/protocol.h>
25 #include <net/xfrm.h>
26 
27 #include "l2tp_core.h"
28 
29 struct l2tp_ip_sock {
30 	/* inet_sock has to be the first member of l2tp_ip_sock */
31 	struct inet_sock	inet;
32 
33 	u32			conn_id;
34 	u32			peer_conn_id;
35 };
36 
37 static DEFINE_RWLOCK(l2tp_ip_lock);
38 static struct hlist_head l2tp_ip_table;
39 static struct hlist_head l2tp_ip_bind_table;
40 
41 static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
42 {
43 	return (struct l2tp_ip_sock *)sk;
44 }
45 
46 static struct sock *__l2tp_ip_bind_lookup(const struct net *net, __be32 laddr,
47 					  __be32 raddr, int dif, u32 tunnel_id)
48 {
49 	struct sock *sk;
50 
51 	sk_for_each_bound(sk, &l2tp_ip_bind_table) {
52 		const struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
53 		const struct inet_sock *inet = inet_sk(sk);
54 
55 		if (!net_eq(sock_net(sk), net))
56 			continue;
57 
58 		if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
59 			continue;
60 
61 		if (inet->inet_rcv_saddr && laddr &&
62 		    inet->inet_rcv_saddr != laddr)
63 			continue;
64 
65 		if (inet->inet_daddr && raddr && inet->inet_daddr != raddr)
66 			continue;
67 
68 		if (l2tp->conn_id != tunnel_id)
69 			continue;
70 
71 		goto found;
72 	}
73 
74 	sk = NULL;
75 found:
76 	return sk;
77 }
78 
79 /* When processing receive frames, there are two cases to
80  * consider. Data frames consist of a non-zero session-id and an
81  * optional cookie. Control frames consist of a regular L2TP header
82  * preceded by 32-bits of zeros.
83  *
84  * L2TPv3 Session Header Over IP
85  *
86  *  0                   1                   2                   3
87  *  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
88  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
89  * |                           Session ID                          |
90  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
91  * |               Cookie (optional, maximum 64 bits)...
92  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
93  *                                                                 |
94  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
95  *
96  * L2TPv3 Control Message Header Over IP
97  *
98  *  0                   1                   2                   3
99  *  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
100  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
101  * |                      (32 bits of zeros)                       |
102  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
103  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
104  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
105  * |                     Control Connection ID                     |
106  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
107  * |               Ns              |               Nr              |
108  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
109  *
110  * All control frames are passed to userspace.
111  */
112 static int l2tp_ip_recv(struct sk_buff *skb)
113 {
114 	struct net *net = dev_net(skb->dev);
115 	struct sock *sk;
116 	u32 session_id;
117 	u32 tunnel_id;
118 	unsigned char *ptr, *optr;
119 	struct l2tp_session *session;
120 	struct l2tp_tunnel *tunnel = NULL;
121 	struct iphdr *iph;
122 	int length;
123 
124 	if (!pskb_may_pull(skb, 4))
125 		goto discard;
126 
127 	/* Point to L2TP header */
128 	optr = ptr = skb->data;
129 	session_id = ntohl(*((__be32 *) ptr));
130 	ptr += 4;
131 
132 	/* RFC3931: L2TP/IP packets have the first 4 bytes containing
133 	 * the session_id. If it is 0, the packet is a L2TP control
134 	 * frame and the session_id value can be discarded.
135 	 */
136 	if (session_id == 0) {
137 		__skb_pull(skb, 4);
138 		goto pass_up;
139 	}
140 
141 	/* Ok, this is a data packet. Lookup the session. */
142 	session = l2tp_session_get(net, session_id);
143 	if (!session)
144 		goto discard;
145 
146 	tunnel = session->tunnel;
147 	if (!tunnel)
148 		goto discard_sess;
149 
150 	/* Trace packet contents, if enabled */
151 	if (tunnel->debug & L2TP_MSG_DATA) {
152 		length = min(32u, skb->len);
153 		if (!pskb_may_pull(skb, length))
154 			goto discard_sess;
155 
156 		/* Point to L2TP header */
157 		optr = ptr = skb->data;
158 		ptr += 4;
159 		pr_debug("%s: ip recv\n", tunnel->name);
160 		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
161 	}
162 
163 	if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
164 		goto discard_sess;
165 
166 	l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
167 	l2tp_session_dec_refcount(session);
168 
169 	return 0;
170 
171 pass_up:
172 	/* Get the tunnel_id from the L2TP header */
173 	if (!pskb_may_pull(skb, 12))
174 		goto discard;
175 
176 	if ((skb->data[0] & 0xc0) != 0xc0)
177 		goto discard;
178 
179 	tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
180 	iph = (struct iphdr *)skb_network_header(skb);
181 
182 	read_lock_bh(&l2tp_ip_lock);
183 	sk = __l2tp_ip_bind_lookup(net, iph->daddr, iph->saddr, inet_iif(skb),
184 				   tunnel_id);
185 	if (!sk) {
186 		read_unlock_bh(&l2tp_ip_lock);
187 		goto discard;
188 	}
189 	sock_hold(sk);
190 	read_unlock_bh(&l2tp_ip_lock);
191 
192 	if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
193 		goto discard_put;
194 
195 	nf_reset_ct(skb);
196 
197 	return sk_receive_skb(sk, skb, 1);
198 
199 discard_sess:
200 	l2tp_session_dec_refcount(session);
201 	goto discard;
202 
203 discard_put:
204 	sock_put(sk);
205 
206 discard:
207 	kfree_skb(skb);
208 	return 0;
209 }
210 
211 static int l2tp_ip_hash(struct sock *sk)
212 {
213 	if (sk_unhashed(sk)) {
214 		write_lock_bh(&l2tp_ip_lock);
215 		sk_add_node(sk, &l2tp_ip_table);
216 		write_unlock_bh(&l2tp_ip_lock);
217 	}
218 	return 0;
219 }
220 
221 static void l2tp_ip_unhash(struct sock *sk)
222 {
223 	if (sk_unhashed(sk))
224 		return;
225 	write_lock_bh(&l2tp_ip_lock);
226 	sk_del_node_init(sk);
227 	write_unlock_bh(&l2tp_ip_lock);
228 }
229 
230 static int l2tp_ip_open(struct sock *sk)
231 {
232 	/* Prevent autobind. We don't have ports. */
233 	inet_sk(sk)->inet_num = IPPROTO_L2TP;
234 
235 	l2tp_ip_hash(sk);
236 	return 0;
237 }
238 
239 static void l2tp_ip_close(struct sock *sk, long timeout)
240 {
241 	write_lock_bh(&l2tp_ip_lock);
242 	hlist_del_init(&sk->sk_bind_node);
243 	sk_del_node_init(sk);
244 	write_unlock_bh(&l2tp_ip_lock);
245 	sk_common_release(sk);
246 }
247 
248 static void l2tp_ip_destroy_sock(struct sock *sk)
249 {
250 	struct sk_buff *skb;
251 	struct l2tp_tunnel *tunnel = sk->sk_user_data;
252 
253 	while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
254 		kfree_skb(skb);
255 
256 	if (tunnel)
257 		l2tp_tunnel_delete(tunnel);
258 }
259 
260 static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
261 {
262 	struct inet_sock *inet = inet_sk(sk);
263 	struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
264 	struct net *net = sock_net(sk);
265 	int ret;
266 	int chk_addr_ret;
267 
268 	if (addr_len < sizeof(struct sockaddr_l2tpip))
269 		return -EINVAL;
270 	if (addr->l2tp_family != AF_INET)
271 		return -EINVAL;
272 
273 	lock_sock(sk);
274 
275 	ret = -EINVAL;
276 	if (!sock_flag(sk, SOCK_ZAPPED))
277 		goto out;
278 
279 	if (sk->sk_state != TCP_CLOSE)
280 		goto out;
281 
282 	chk_addr_ret = inet_addr_type(net, addr->l2tp_addr.s_addr);
283 	ret = -EADDRNOTAVAIL;
284 	if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
285 	    chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
286 		goto out;
287 
288 	if (addr->l2tp_addr.s_addr)
289 		inet->inet_rcv_saddr = inet->inet_saddr = addr->l2tp_addr.s_addr;
290 	if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
291 		inet->inet_saddr = 0;  /* Use device */
292 
293 	write_lock_bh(&l2tp_ip_lock);
294 	if (__l2tp_ip_bind_lookup(net, addr->l2tp_addr.s_addr, 0,
295 				  sk->sk_bound_dev_if, addr->l2tp_conn_id)) {
296 		write_unlock_bh(&l2tp_ip_lock);
297 		ret = -EADDRINUSE;
298 		goto out;
299 	}
300 
301 	sk_dst_reset(sk);
302 	l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
303 
304 	sk_add_bind_node(sk, &l2tp_ip_bind_table);
305 	sk_del_node_init(sk);
306 	write_unlock_bh(&l2tp_ip_lock);
307 
308 	ret = 0;
309 	sock_reset_flag(sk, SOCK_ZAPPED);
310 
311 out:
312 	release_sock(sk);
313 
314 	return ret;
315 }
316 
317 static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
318 {
319 	struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
320 	int rc;
321 
322 	if (addr_len < sizeof(*lsa))
323 		return -EINVAL;
324 
325 	if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
326 		return -EINVAL;
327 
328 	lock_sock(sk);
329 
330 	/* Must bind first - autobinding does not work */
331 	if (sock_flag(sk, SOCK_ZAPPED)) {
332 		rc = -EINVAL;
333 		goto out_sk;
334 	}
335 
336 	rc = __ip4_datagram_connect(sk, uaddr, addr_len);
337 	if (rc < 0)
338 		goto out_sk;
339 
340 	l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
341 
342 	write_lock_bh(&l2tp_ip_lock);
343 	hlist_del_init(&sk->sk_bind_node);
344 	sk_add_bind_node(sk, &l2tp_ip_bind_table);
345 	write_unlock_bh(&l2tp_ip_lock);
346 
347 out_sk:
348 	release_sock(sk);
349 
350 	return rc;
351 }
352 
353 static int l2tp_ip_disconnect(struct sock *sk, int flags)
354 {
355 	if (sock_flag(sk, SOCK_ZAPPED))
356 		return 0;
357 
358 	return __udp_disconnect(sk, flags);
359 }
360 
361 static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
362 			   int peer)
363 {
364 	struct sock *sk		= sock->sk;
365 	struct inet_sock *inet	= inet_sk(sk);
366 	struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
367 	struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
368 
369 	memset(lsa, 0, sizeof(*lsa));
370 	lsa->l2tp_family = AF_INET;
371 	if (peer) {
372 		if (!inet->inet_dport)
373 			return -ENOTCONN;
374 		lsa->l2tp_conn_id = lsk->peer_conn_id;
375 		lsa->l2tp_addr.s_addr = inet->inet_daddr;
376 	} else {
377 		__be32 addr = inet->inet_rcv_saddr;
378 		if (!addr)
379 			addr = inet->inet_saddr;
380 		lsa->l2tp_conn_id = lsk->conn_id;
381 		lsa->l2tp_addr.s_addr = addr;
382 	}
383 	return sizeof(*lsa);
384 }
385 
386 static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
387 {
388 	int rc;
389 
390 	/* Charge it to the socket, dropping if the queue is full. */
391 	rc = sock_queue_rcv_skb(sk, skb);
392 	if (rc < 0)
393 		goto drop;
394 
395 	return 0;
396 
397 drop:
398 	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
399 	kfree_skb(skb);
400 	return 0;
401 }
402 
403 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
404  * control frames.
405  */
406 static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
407 {
408 	struct sk_buff *skb;
409 	int rc;
410 	struct inet_sock *inet = inet_sk(sk);
411 	struct rtable *rt = NULL;
412 	struct flowi4 *fl4;
413 	int connected = 0;
414 	__be32 daddr;
415 
416 	lock_sock(sk);
417 
418 	rc = -ENOTCONN;
419 	if (sock_flag(sk, SOCK_DEAD))
420 		goto out;
421 
422 	/* Get and verify the address. */
423 	if (msg->msg_name) {
424 		DECLARE_SOCKADDR(struct sockaddr_l2tpip *, lip, msg->msg_name);
425 		rc = -EINVAL;
426 		if (msg->msg_namelen < sizeof(*lip))
427 			goto out;
428 
429 		if (lip->l2tp_family != AF_INET) {
430 			rc = -EAFNOSUPPORT;
431 			if (lip->l2tp_family != AF_UNSPEC)
432 				goto out;
433 		}
434 
435 		daddr = lip->l2tp_addr.s_addr;
436 	} else {
437 		rc = -EDESTADDRREQ;
438 		if (sk->sk_state != TCP_ESTABLISHED)
439 			goto out;
440 
441 		daddr = inet->inet_daddr;
442 		connected = 1;
443 	}
444 
445 	/* Allocate a socket buffer */
446 	rc = -ENOMEM;
447 	skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
448 			   4 + len, 0, GFP_KERNEL);
449 	if (!skb)
450 		goto error;
451 
452 	/* Reserve space for headers, putting IP header on 4-byte boundary. */
453 	skb_reserve(skb, 2 + NET_SKB_PAD);
454 	skb_reset_network_header(skb);
455 	skb_reserve(skb, sizeof(struct iphdr));
456 	skb_reset_transport_header(skb);
457 
458 	/* Insert 0 session_id */
459 	*((__be32 *) skb_put(skb, 4)) = 0;
460 
461 	/* Copy user data into skb */
462 	rc = memcpy_from_msg(skb_put(skb, len), msg, len);
463 	if (rc < 0) {
464 		kfree_skb(skb);
465 		goto error;
466 	}
467 
468 	fl4 = &inet->cork.fl.u.ip4;
469 	if (connected)
470 		rt = (struct rtable *) __sk_dst_check(sk, 0);
471 
472 	rcu_read_lock();
473 	if (rt == NULL) {
474 		const struct ip_options_rcu *inet_opt;
475 
476 		inet_opt = rcu_dereference(inet->inet_opt);
477 
478 		/* Use correct destination address if we have options. */
479 		if (inet_opt && inet_opt->opt.srr)
480 			daddr = inet_opt->opt.faddr;
481 
482 		/* If this fails, retransmit mechanism of transport layer will
483 		 * keep trying until route appears or the connection times
484 		 * itself out.
485 		 */
486 		rt = ip_route_output_ports(sock_net(sk), fl4, sk,
487 					   daddr, inet->inet_saddr,
488 					   inet->inet_dport, inet->inet_sport,
489 					   sk->sk_protocol, RT_CONN_FLAGS(sk),
490 					   sk->sk_bound_dev_if);
491 		if (IS_ERR(rt))
492 			goto no_route;
493 		if (connected) {
494 			sk_setup_caps(sk, &rt->dst);
495 		} else {
496 			skb_dst_set(skb, &rt->dst);
497 			goto xmit;
498 		}
499 	}
500 
501 	/* We dont need to clone dst here, it is guaranteed to not disappear.
502 	 *  __dev_xmit_skb() might force a refcount if needed.
503 	 */
504 	skb_dst_set_noref(skb, &rt->dst);
505 
506 xmit:
507 	/* Queue the packet to IP for output */
508 	rc = ip_queue_xmit(sk, skb, &inet->cork.fl);
509 	rcu_read_unlock();
510 
511 error:
512 	if (rc >= 0)
513 		rc = len;
514 
515 out:
516 	release_sock(sk);
517 	return rc;
518 
519 no_route:
520 	rcu_read_unlock();
521 	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
522 	kfree_skb(skb);
523 	rc = -EHOSTUNREACH;
524 	goto out;
525 }
526 
527 static int l2tp_ip_recvmsg(struct sock *sk, struct msghdr *msg,
528 			   size_t len, int noblock, int flags, int *addr_len)
529 {
530 	struct inet_sock *inet = inet_sk(sk);
531 	size_t copied = 0;
532 	int err = -EOPNOTSUPP;
533 	DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
534 	struct sk_buff *skb;
535 
536 	if (flags & MSG_OOB)
537 		goto out;
538 
539 	skb = skb_recv_datagram(sk, flags, noblock, &err);
540 	if (!skb)
541 		goto out;
542 
543 	copied = skb->len;
544 	if (len < copied) {
545 		msg->msg_flags |= MSG_TRUNC;
546 		copied = len;
547 	}
548 
549 	err = skb_copy_datagram_msg(skb, 0, msg, copied);
550 	if (err)
551 		goto done;
552 
553 	sock_recv_timestamp(msg, sk, skb);
554 
555 	/* Copy the address. */
556 	if (sin) {
557 		sin->sin_family = AF_INET;
558 		sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
559 		sin->sin_port = 0;
560 		memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
561 		*addr_len = sizeof(*sin);
562 	}
563 	if (inet->cmsg_flags)
564 		ip_cmsg_recv(msg, skb);
565 	if (flags & MSG_TRUNC)
566 		copied = skb->len;
567 done:
568 	skb_free_datagram(sk, skb);
569 out:
570 	return err ? err : copied;
571 }
572 
573 int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg)
574 {
575 	struct sk_buff *skb;
576 	int amount;
577 
578 	switch (cmd) {
579 	case SIOCOUTQ:
580 		amount = sk_wmem_alloc_get(sk);
581 		break;
582 	case SIOCINQ:
583 		spin_lock_bh(&sk->sk_receive_queue.lock);
584 		skb = skb_peek(&sk->sk_receive_queue);
585 		amount = skb ? skb->len : 0;
586 		spin_unlock_bh(&sk->sk_receive_queue.lock);
587 		break;
588 
589 	default:
590 		return -ENOIOCTLCMD;
591 	}
592 
593 	return put_user(amount, (int __user *)arg);
594 }
595 EXPORT_SYMBOL(l2tp_ioctl);
596 
597 static struct proto l2tp_ip_prot = {
598 	.name		   = "L2TP/IP",
599 	.owner		   = THIS_MODULE,
600 	.init		   = l2tp_ip_open,
601 	.close		   = l2tp_ip_close,
602 	.bind		   = l2tp_ip_bind,
603 	.connect	   = l2tp_ip_connect,
604 	.disconnect	   = l2tp_ip_disconnect,
605 	.ioctl		   = l2tp_ioctl,
606 	.destroy	   = l2tp_ip_destroy_sock,
607 	.setsockopt	   = ip_setsockopt,
608 	.getsockopt	   = ip_getsockopt,
609 	.sendmsg	   = l2tp_ip_sendmsg,
610 	.recvmsg	   = l2tp_ip_recvmsg,
611 	.backlog_rcv	   = l2tp_ip_backlog_recv,
612 	.hash		   = l2tp_ip_hash,
613 	.unhash		   = l2tp_ip_unhash,
614 	.obj_size	   = sizeof(struct l2tp_ip_sock),
615 #ifdef CONFIG_COMPAT
616 	.compat_setsockopt = compat_ip_setsockopt,
617 	.compat_getsockopt = compat_ip_getsockopt,
618 #endif
619 };
620 
621 static const struct proto_ops l2tp_ip_ops = {
622 	.family		   = PF_INET,
623 	.owner		   = THIS_MODULE,
624 	.release	   = inet_release,
625 	.bind		   = inet_bind,
626 	.connect	   = inet_dgram_connect,
627 	.socketpair	   = sock_no_socketpair,
628 	.accept		   = sock_no_accept,
629 	.getname	   = l2tp_ip_getname,
630 	.poll		   = datagram_poll,
631 	.ioctl		   = inet_ioctl,
632 	.gettstamp	   = sock_gettstamp,
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 
647 static 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 };
653 
654 static struct net_protocol l2tp_ip_protocol __read_mostly = {
655 	.handler	= l2tp_ip_recv,
656 	.netns_ok	= 1,
657 };
658 
659 static int __init l2tp_ip_init(void)
660 {
661 	int err;
662 
663 	pr_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 
676 out1:
677 	proto_unregister(&l2tp_ip_prot);
678 out:
679 	return err;
680 }
681 
682 static 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 
689 module_init(l2tp_ip_init);
690 module_exit(l2tp_ip_exit);
691 
692 MODULE_LICENSE("GPL");
693 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
694 MODULE_DESCRIPTION("L2TP over IP");
695 MODULE_VERSION("1.0");
696 
697 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
698  * enums
699  */
700 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP);
701 MODULE_ALIAS_NET_PF_PROTO(PF_INET, IPPROTO_L2TP);
702