xref: /openbmc/linux/net/l2tp/l2tp_ip6.c (revision 0edbfea5)
1 /*
2  * L2TPv3 IP encapsulation support for IPv6
3  *
4  * Copyright (c) 2012 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 <linux/in6.h>
22 #include <net/sock.h>
23 #include <net/ip.h>
24 #include <net/icmp.h>
25 #include <net/udp.h>
26 #include <net/inet_common.h>
27 #include <net/inet_hashtables.h>
28 #include <net/inet6_hashtables.h>
29 #include <net/tcp_states.h>
30 #include <net/protocol.h>
31 #include <net/xfrm.h>
32 
33 #include <net/transp_v6.h>
34 #include <net/addrconf.h>
35 #include <net/ip6_route.h>
36 
37 #include "l2tp_core.h"
38 
39 struct l2tp_ip6_sock {
40 	/* inet_sock has to be the first member of l2tp_ip6_sock */
41 	struct inet_sock	inet;
42 
43 	u32			conn_id;
44 	u32			peer_conn_id;
45 
46 	/* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
47 	   inet6_sk_generic */
48 	struct ipv6_pinfo	inet6;
49 };
50 
51 static DEFINE_RWLOCK(l2tp_ip6_lock);
52 static struct hlist_head l2tp_ip6_table;
53 static struct hlist_head l2tp_ip6_bind_table;
54 
55 static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
56 {
57 	return (struct l2tp_ip6_sock *)sk;
58 }
59 
60 static struct sock *__l2tp_ip6_bind_lookup(struct net *net,
61 					   struct in6_addr *laddr,
62 					   int dif, u32 tunnel_id)
63 {
64 	struct sock *sk;
65 
66 	sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
67 		const struct in6_addr *addr = inet6_rcv_saddr(sk);
68 		struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
69 
70 		if (l2tp == NULL)
71 			continue;
72 
73 		if ((l2tp->conn_id == tunnel_id) &&
74 		    net_eq(sock_net(sk), net) &&
75 		    !(addr && ipv6_addr_equal(addr, laddr)) &&
76 		    !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif))
77 			goto found;
78 	}
79 
80 	sk = NULL;
81 found:
82 	return sk;
83 }
84 
85 static inline struct sock *l2tp_ip6_bind_lookup(struct net *net,
86 						struct in6_addr *laddr,
87 						int dif, u32 tunnel_id)
88 {
89 	struct sock *sk = __l2tp_ip6_bind_lookup(net, laddr, dif, tunnel_id);
90 	if (sk)
91 		sock_hold(sk);
92 
93 	return sk;
94 }
95 
96 /* When processing receive frames, there are two cases to
97  * consider. Data frames consist of a non-zero session-id and an
98  * optional cookie. Control frames consist of a regular L2TP header
99  * preceded by 32-bits of zeros.
100  *
101  * L2TPv3 Session Header Over IP
102  *
103  *  0                   1                   2                   3
104  *  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
105  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
106  * |                           Session ID                          |
107  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
108  * |               Cookie (optional, maximum 64 bits)...
109  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
110  *                                                                 |
111  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
112  *
113  * L2TPv3 Control Message Header Over IP
114  *
115  *  0                   1                   2                   3
116  *  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
117  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
118  * |                      (32 bits of zeros)                       |
119  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
120  * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
121  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
122  * |                     Control Connection ID                     |
123  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
124  * |               Ns              |               Nr              |
125  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
126  *
127  * All control frames are passed to userspace.
128  */
129 static int l2tp_ip6_recv(struct sk_buff *skb)
130 {
131 	struct net *net = dev_net(skb->dev);
132 	struct sock *sk;
133 	u32 session_id;
134 	u32 tunnel_id;
135 	unsigned char *ptr, *optr;
136 	struct l2tp_session *session;
137 	struct l2tp_tunnel *tunnel = NULL;
138 	int length;
139 
140 	if (!pskb_may_pull(skb, 4))
141 		goto discard;
142 
143 	/* Point to L2TP header */
144 	optr = ptr = skb->data;
145 	session_id = ntohl(*((__be32 *) ptr));
146 	ptr += 4;
147 
148 	/* RFC3931: L2TP/IP packets have the first 4 bytes containing
149 	 * the session_id. If it is 0, the packet is a L2TP control
150 	 * frame and the session_id value can be discarded.
151 	 */
152 	if (session_id == 0) {
153 		__skb_pull(skb, 4);
154 		goto pass_up;
155 	}
156 
157 	/* Ok, this is a data packet. Lookup the session. */
158 	session = l2tp_session_find(net, NULL, session_id);
159 	if (session == NULL)
160 		goto discard;
161 
162 	tunnel = session->tunnel;
163 	if (tunnel == NULL)
164 		goto discard;
165 
166 	/* Trace packet contents, if enabled */
167 	if (tunnel->debug & L2TP_MSG_DATA) {
168 		length = min(32u, skb->len);
169 		if (!pskb_may_pull(skb, length))
170 			goto discard;
171 
172 		/* Point to L2TP header */
173 		optr = ptr = skb->data;
174 		ptr += 4;
175 		pr_debug("%s: ip recv\n", tunnel->name);
176 		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
177 	}
178 
179 	l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
180 			 tunnel->recv_payload_hook);
181 	return 0;
182 
183 pass_up:
184 	/* Get the tunnel_id from the L2TP header */
185 	if (!pskb_may_pull(skb, 12))
186 		goto discard;
187 
188 	if ((skb->data[0] & 0xc0) != 0xc0)
189 		goto discard;
190 
191 	tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
192 	tunnel = l2tp_tunnel_find(net, tunnel_id);
193 	if (tunnel != NULL)
194 		sk = tunnel->sock;
195 	else {
196 		struct ipv6hdr *iph = ipv6_hdr(skb);
197 
198 		read_lock_bh(&l2tp_ip6_lock);
199 		sk = __l2tp_ip6_bind_lookup(net, &iph->daddr,
200 					    0, tunnel_id);
201 		read_unlock_bh(&l2tp_ip6_lock);
202 	}
203 
204 	if (sk == NULL)
205 		goto discard;
206 
207 	sock_hold(sk);
208 
209 	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
210 		goto discard_put;
211 
212 	nf_reset(skb);
213 
214 	return sk_receive_skb(sk, skb, 1);
215 
216 discard_put:
217 	sock_put(sk);
218 
219 discard:
220 	kfree_skb(skb);
221 	return 0;
222 }
223 
224 static int l2tp_ip6_open(struct sock *sk)
225 {
226 	/* Prevent autobind. We don't have ports. */
227 	inet_sk(sk)->inet_num = IPPROTO_L2TP;
228 
229 	write_lock_bh(&l2tp_ip6_lock);
230 	sk_add_node(sk, &l2tp_ip6_table);
231 	write_unlock_bh(&l2tp_ip6_lock);
232 
233 	return 0;
234 }
235 
236 static void l2tp_ip6_close(struct sock *sk, long timeout)
237 {
238 	write_lock_bh(&l2tp_ip6_lock);
239 	hlist_del_init(&sk->sk_bind_node);
240 	sk_del_node_init(sk);
241 	write_unlock_bh(&l2tp_ip6_lock);
242 
243 	sk_common_release(sk);
244 }
245 
246 static void l2tp_ip6_destroy_sock(struct sock *sk)
247 {
248 	struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
249 
250 	lock_sock(sk);
251 	ip6_flush_pending_frames(sk);
252 	release_sock(sk);
253 
254 	if (tunnel) {
255 		l2tp_tunnel_closeall(tunnel);
256 		sock_put(sk);
257 	}
258 
259 	inet6_destroy_sock(sk);
260 }
261 
262 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
263 {
264 	struct inet_sock *inet = inet_sk(sk);
265 	struct ipv6_pinfo *np = inet6_sk(sk);
266 	struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
267 	struct net *net = sock_net(sk);
268 	__be32 v4addr = 0;
269 	int addr_type;
270 	int err;
271 
272 	if (!sock_flag(sk, SOCK_ZAPPED))
273 		return -EINVAL;
274 	if (addr->l2tp_family != AF_INET6)
275 		return -EINVAL;
276 	if (addr_len < sizeof(*addr))
277 		return -EINVAL;
278 
279 	addr_type = ipv6_addr_type(&addr->l2tp_addr);
280 
281 	/* l2tp_ip6 sockets are IPv6 only */
282 	if (addr_type == IPV6_ADDR_MAPPED)
283 		return -EADDRNOTAVAIL;
284 
285 	/* L2TP is point-point, not multicast */
286 	if (addr_type & IPV6_ADDR_MULTICAST)
287 		return -EADDRNOTAVAIL;
288 
289 	err = -EADDRINUSE;
290 	read_lock_bh(&l2tp_ip6_lock);
291 	if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr,
292 				   sk->sk_bound_dev_if, addr->l2tp_conn_id))
293 		goto out_in_use;
294 	read_unlock_bh(&l2tp_ip6_lock);
295 
296 	lock_sock(sk);
297 
298 	err = -EINVAL;
299 	if (sk->sk_state != TCP_CLOSE)
300 		goto out_unlock;
301 
302 	/* Check if the address belongs to the host. */
303 	rcu_read_lock();
304 	if (addr_type != IPV6_ADDR_ANY) {
305 		struct net_device *dev = NULL;
306 
307 		if (addr_type & IPV6_ADDR_LINKLOCAL) {
308 			if (addr_len >= sizeof(struct sockaddr_in6) &&
309 			    addr->l2tp_scope_id) {
310 				/* Override any existing binding, if another
311 				 * one is supplied by user.
312 				 */
313 				sk->sk_bound_dev_if = addr->l2tp_scope_id;
314 			}
315 
316 			/* Binding to link-local address requires an
317 			   interface */
318 			if (!sk->sk_bound_dev_if)
319 				goto out_unlock_rcu;
320 
321 			err = -ENODEV;
322 			dev = dev_get_by_index_rcu(sock_net(sk),
323 						   sk->sk_bound_dev_if);
324 			if (!dev)
325 				goto out_unlock_rcu;
326 		}
327 
328 		/* ipv4 addr of the socket is invalid.  Only the
329 		 * unspecified and mapped address have a v4 equivalent.
330 		 */
331 		v4addr = LOOPBACK4_IPV6;
332 		err = -EADDRNOTAVAIL;
333 		if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
334 			goto out_unlock_rcu;
335 	}
336 	rcu_read_unlock();
337 
338 	inet->inet_rcv_saddr = inet->inet_saddr = v4addr;
339 	sk->sk_v6_rcv_saddr = addr->l2tp_addr;
340 	np->saddr = addr->l2tp_addr;
341 
342 	l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
343 
344 	write_lock_bh(&l2tp_ip6_lock);
345 	sk_add_bind_node(sk, &l2tp_ip6_bind_table);
346 	sk_del_node_init(sk);
347 	write_unlock_bh(&l2tp_ip6_lock);
348 
349 	sock_reset_flag(sk, SOCK_ZAPPED);
350 	release_sock(sk);
351 	return 0;
352 
353 out_unlock_rcu:
354 	rcu_read_unlock();
355 out_unlock:
356 	release_sock(sk);
357 	return err;
358 
359 out_in_use:
360 	read_unlock_bh(&l2tp_ip6_lock);
361 	return err;
362 }
363 
364 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
365 			    int addr_len)
366 {
367 	struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
368 	struct sockaddr_in6	*usin = (struct sockaddr_in6 *) uaddr;
369 	struct in6_addr	*daddr;
370 	int	addr_type;
371 	int rc;
372 
373 	if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
374 		return -EINVAL;
375 
376 	if (addr_len < sizeof(*lsa))
377 		return -EINVAL;
378 
379 	if (usin->sin6_family != AF_INET6)
380 		return -EINVAL;
381 
382 	addr_type = ipv6_addr_type(&usin->sin6_addr);
383 	if (addr_type & IPV6_ADDR_MULTICAST)
384 		return -EINVAL;
385 
386 	if (addr_type & IPV6_ADDR_MAPPED) {
387 		daddr = &usin->sin6_addr;
388 		if (ipv4_is_multicast(daddr->s6_addr32[3]))
389 			return -EINVAL;
390 	}
391 
392 	rc = ip6_datagram_connect(sk, uaddr, addr_len);
393 
394 	lock_sock(sk);
395 
396 	l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
397 
398 	write_lock_bh(&l2tp_ip6_lock);
399 	hlist_del_init(&sk->sk_bind_node);
400 	sk_add_bind_node(sk, &l2tp_ip6_bind_table);
401 	write_unlock_bh(&l2tp_ip6_lock);
402 
403 	release_sock(sk);
404 
405 	return rc;
406 }
407 
408 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
409 {
410 	if (sock_flag(sk, SOCK_ZAPPED))
411 		return 0;
412 
413 	return udp_disconnect(sk, flags);
414 }
415 
416 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
417 			    int *uaddr_len, int peer)
418 {
419 	struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
420 	struct sock *sk = sock->sk;
421 	struct ipv6_pinfo *np = inet6_sk(sk);
422 	struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
423 
424 	lsa->l2tp_family = AF_INET6;
425 	lsa->l2tp_flowinfo = 0;
426 	lsa->l2tp_scope_id = 0;
427 	lsa->l2tp_unused = 0;
428 	if (peer) {
429 		if (!lsk->peer_conn_id)
430 			return -ENOTCONN;
431 		lsa->l2tp_conn_id = lsk->peer_conn_id;
432 		lsa->l2tp_addr = sk->sk_v6_daddr;
433 		if (np->sndflow)
434 			lsa->l2tp_flowinfo = np->flow_label;
435 	} else {
436 		if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
437 			lsa->l2tp_addr = np->saddr;
438 		else
439 			lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
440 
441 		lsa->l2tp_conn_id = lsk->conn_id;
442 	}
443 	if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
444 		lsa->l2tp_scope_id = sk->sk_bound_dev_if;
445 	*uaddr_len = sizeof(*lsa);
446 	return 0;
447 }
448 
449 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
450 {
451 	int rc;
452 
453 	/* Charge it to the socket, dropping if the queue is full. */
454 	rc = sock_queue_rcv_skb(sk, skb);
455 	if (rc < 0)
456 		goto drop;
457 
458 	return 0;
459 
460 drop:
461 	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
462 	kfree_skb(skb);
463 	return -1;
464 }
465 
466 static int l2tp_ip6_push_pending_frames(struct sock *sk)
467 {
468 	struct sk_buff *skb;
469 	__be32 *transhdr = NULL;
470 	int err = 0;
471 
472 	skb = skb_peek(&sk->sk_write_queue);
473 	if (skb == NULL)
474 		goto out;
475 
476 	transhdr = (__be32 *)skb_transport_header(skb);
477 	*transhdr = 0;
478 
479 	err = ip6_push_pending_frames(sk);
480 
481 out:
482 	return err;
483 }
484 
485 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
486  * control frames.
487  */
488 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
489 {
490 	struct ipv6_txoptions opt_space;
491 	DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
492 	struct in6_addr *daddr, *final_p, final;
493 	struct ipv6_pinfo *np = inet6_sk(sk);
494 	struct ipv6_txoptions *opt_to_free = NULL;
495 	struct ipv6_txoptions *opt = NULL;
496 	struct ip6_flowlabel *flowlabel = NULL;
497 	struct dst_entry *dst = NULL;
498 	struct flowi6 fl6;
499 	struct sockcm_cookie sockc_unused = {0};
500 	struct ipcm6_cookie ipc6;
501 	int addr_len = msg->msg_namelen;
502 	int transhdrlen = 4; /* zero session-id */
503 	int ulen = len + transhdrlen;
504 	int err;
505 
506 	/* Rough check on arithmetic overflow,
507 	   better check is made in ip6_append_data().
508 	 */
509 	if (len > INT_MAX)
510 		return -EMSGSIZE;
511 
512 	/* Mirror BSD error message compatibility */
513 	if (msg->msg_flags & MSG_OOB)
514 		return -EOPNOTSUPP;
515 
516 	/*
517 	 *	Get and verify the address.
518 	 */
519 	memset(&fl6, 0, sizeof(fl6));
520 
521 	fl6.flowi6_mark = sk->sk_mark;
522 
523 	ipc6.hlimit = -1;
524 	ipc6.tclass = -1;
525 	ipc6.dontfrag = -1;
526 
527 	if (lsa) {
528 		if (addr_len < SIN6_LEN_RFC2133)
529 			return -EINVAL;
530 
531 		if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
532 			return -EAFNOSUPPORT;
533 
534 		daddr = &lsa->l2tp_addr;
535 		if (np->sndflow) {
536 			fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
537 			if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
538 				flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
539 				if (flowlabel == NULL)
540 					return -EINVAL;
541 			}
542 		}
543 
544 		/*
545 		 * Otherwise it will be difficult to maintain
546 		 * sk->sk_dst_cache.
547 		 */
548 		if (sk->sk_state == TCP_ESTABLISHED &&
549 		    ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
550 			daddr = &sk->sk_v6_daddr;
551 
552 		if (addr_len >= sizeof(struct sockaddr_in6) &&
553 		    lsa->l2tp_scope_id &&
554 		    ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
555 			fl6.flowi6_oif = lsa->l2tp_scope_id;
556 	} else {
557 		if (sk->sk_state != TCP_ESTABLISHED)
558 			return -EDESTADDRREQ;
559 
560 		daddr = &sk->sk_v6_daddr;
561 		fl6.flowlabel = np->flow_label;
562 	}
563 
564 	if (fl6.flowi6_oif == 0)
565 		fl6.flowi6_oif = sk->sk_bound_dev_if;
566 
567 	if (msg->msg_controllen) {
568 		opt = &opt_space;
569 		memset(opt, 0, sizeof(struct ipv6_txoptions));
570 		opt->tot_len = sizeof(struct ipv6_txoptions);
571 		ipc6.opt = opt;
572 
573 		err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6,
574 					    &sockc_unused);
575 		if (err < 0) {
576 			fl6_sock_release(flowlabel);
577 			return err;
578 		}
579 		if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
580 			flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
581 			if (flowlabel == NULL)
582 				return -EINVAL;
583 		}
584 		if (!(opt->opt_nflen|opt->opt_flen))
585 			opt = NULL;
586 	}
587 
588 	if (!opt) {
589 		opt = txopt_get(np);
590 		opt_to_free = opt;
591 	}
592 	if (flowlabel)
593 		opt = fl6_merge_options(&opt_space, flowlabel, opt);
594 	opt = ipv6_fixup_options(&opt_space, opt);
595 	ipc6.opt = opt;
596 
597 	fl6.flowi6_proto = sk->sk_protocol;
598 	if (!ipv6_addr_any(daddr))
599 		fl6.daddr = *daddr;
600 	else
601 		fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
602 	if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
603 		fl6.saddr = np->saddr;
604 
605 	final_p = fl6_update_dst(&fl6, opt, &final);
606 
607 	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
608 		fl6.flowi6_oif = np->mcast_oif;
609 	else if (!fl6.flowi6_oif)
610 		fl6.flowi6_oif = np->ucast_oif;
611 
612 	security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
613 
614 	dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
615 	if (IS_ERR(dst)) {
616 		err = PTR_ERR(dst);
617 		goto out;
618 	}
619 
620 	if (ipc6.hlimit < 0)
621 		ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
622 
623 	if (ipc6.tclass < 0)
624 		ipc6.tclass = np->tclass;
625 
626 	if (ipc6.dontfrag < 0)
627 		ipc6.dontfrag = np->dontfrag;
628 
629 	if (msg->msg_flags & MSG_CONFIRM)
630 		goto do_confirm;
631 
632 back_from_confirm:
633 	lock_sock(sk);
634 	err = ip6_append_data(sk, ip_generic_getfrag, msg,
635 			      ulen, transhdrlen, &ipc6,
636 			      &fl6, (struct rt6_info *)dst,
637 			      msg->msg_flags, &sockc_unused);
638 	if (err)
639 		ip6_flush_pending_frames(sk);
640 	else if (!(msg->msg_flags & MSG_MORE))
641 		err = l2tp_ip6_push_pending_frames(sk);
642 	release_sock(sk);
643 done:
644 	dst_release(dst);
645 out:
646 	fl6_sock_release(flowlabel);
647 	txopt_put(opt_to_free);
648 
649 	return err < 0 ? err : len;
650 
651 do_confirm:
652 	dst_confirm(dst);
653 	if (!(msg->msg_flags & MSG_PROBE) || len)
654 		goto back_from_confirm;
655 	err = 0;
656 	goto done;
657 }
658 
659 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
660 			    int noblock, int flags, int *addr_len)
661 {
662 	struct ipv6_pinfo *np = inet6_sk(sk);
663 	DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
664 	size_t copied = 0;
665 	int err = -EOPNOTSUPP;
666 	struct sk_buff *skb;
667 
668 	if (flags & MSG_OOB)
669 		goto out;
670 
671 	if (addr_len)
672 		*addr_len = sizeof(*lsa);
673 
674 	if (flags & MSG_ERRQUEUE)
675 		return ipv6_recv_error(sk, msg, len, addr_len);
676 
677 	skb = skb_recv_datagram(sk, flags, noblock, &err);
678 	if (!skb)
679 		goto out;
680 
681 	copied = skb->len;
682 	if (len < copied) {
683 		msg->msg_flags |= MSG_TRUNC;
684 		copied = len;
685 	}
686 
687 	err = skb_copy_datagram_msg(skb, 0, msg, copied);
688 	if (err)
689 		goto done;
690 
691 	sock_recv_timestamp(msg, sk, skb);
692 
693 	/* Copy the address. */
694 	if (lsa) {
695 		lsa->l2tp_family = AF_INET6;
696 		lsa->l2tp_unused = 0;
697 		lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
698 		lsa->l2tp_flowinfo = 0;
699 		lsa->l2tp_scope_id = 0;
700 		lsa->l2tp_conn_id = 0;
701 		if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
702 			lsa->l2tp_scope_id = inet6_iif(skb);
703 	}
704 
705 	if (np->rxopt.all)
706 		ip6_datagram_recv_ctl(sk, msg, skb);
707 
708 	if (flags & MSG_TRUNC)
709 		copied = skb->len;
710 done:
711 	skb_free_datagram(sk, skb);
712 out:
713 	return err ? err : copied;
714 }
715 
716 static struct proto l2tp_ip6_prot = {
717 	.name		   = "L2TP/IPv6",
718 	.owner		   = THIS_MODULE,
719 	.init		   = l2tp_ip6_open,
720 	.close		   = l2tp_ip6_close,
721 	.bind		   = l2tp_ip6_bind,
722 	.connect	   = l2tp_ip6_connect,
723 	.disconnect	   = l2tp_ip6_disconnect,
724 	.ioctl		   = udp_ioctl,
725 	.destroy	   = l2tp_ip6_destroy_sock,
726 	.setsockopt	   = ipv6_setsockopt,
727 	.getsockopt	   = ipv6_getsockopt,
728 	.sendmsg	   = l2tp_ip6_sendmsg,
729 	.recvmsg	   = l2tp_ip6_recvmsg,
730 	.backlog_rcv	   = l2tp_ip6_backlog_recv,
731 	.hash		   = inet6_hash,
732 	.unhash		   = inet_unhash,
733 	.obj_size	   = sizeof(struct l2tp_ip6_sock),
734 #ifdef CONFIG_COMPAT
735 	.compat_setsockopt = compat_ipv6_setsockopt,
736 	.compat_getsockopt = compat_ipv6_getsockopt,
737 #endif
738 };
739 
740 static const struct proto_ops l2tp_ip6_ops = {
741 	.family		   = PF_INET6,
742 	.owner		   = THIS_MODULE,
743 	.release	   = inet6_release,
744 	.bind		   = inet6_bind,
745 	.connect	   = inet_dgram_connect,
746 	.socketpair	   = sock_no_socketpair,
747 	.accept		   = sock_no_accept,
748 	.getname	   = l2tp_ip6_getname,
749 	.poll		   = datagram_poll,
750 	.ioctl		   = inet6_ioctl,
751 	.listen		   = sock_no_listen,
752 	.shutdown	   = inet_shutdown,
753 	.setsockopt	   = sock_common_setsockopt,
754 	.getsockopt	   = sock_common_getsockopt,
755 	.sendmsg	   = inet_sendmsg,
756 	.recvmsg	   = sock_common_recvmsg,
757 	.mmap		   = sock_no_mmap,
758 	.sendpage	   = sock_no_sendpage,
759 #ifdef CONFIG_COMPAT
760 	.compat_setsockopt = compat_sock_common_setsockopt,
761 	.compat_getsockopt = compat_sock_common_getsockopt,
762 #endif
763 };
764 
765 static struct inet_protosw l2tp_ip6_protosw = {
766 	.type		= SOCK_DGRAM,
767 	.protocol	= IPPROTO_L2TP,
768 	.prot		= &l2tp_ip6_prot,
769 	.ops		= &l2tp_ip6_ops,
770 };
771 
772 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
773 	.handler	= l2tp_ip6_recv,
774 };
775 
776 static int __init l2tp_ip6_init(void)
777 {
778 	int err;
779 
780 	pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
781 
782 	err = proto_register(&l2tp_ip6_prot, 1);
783 	if (err != 0)
784 		goto out;
785 
786 	err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
787 	if (err)
788 		goto out1;
789 
790 	inet6_register_protosw(&l2tp_ip6_protosw);
791 	return 0;
792 
793 out1:
794 	proto_unregister(&l2tp_ip6_prot);
795 out:
796 	return err;
797 }
798 
799 static void __exit l2tp_ip6_exit(void)
800 {
801 	inet6_unregister_protosw(&l2tp_ip6_protosw);
802 	inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
803 	proto_unregister(&l2tp_ip6_prot);
804 }
805 
806 module_init(l2tp_ip6_init);
807 module_exit(l2tp_ip6_exit);
808 
809 MODULE_LICENSE("GPL");
810 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
811 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
812 MODULE_VERSION("1.0");
813 
814 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
815  * enums
816  */
817 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
818 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);
819