xref: /kernel/linux/linux-5.10/net/l2tp/l2tp_ip6.c (revision 8c2ecf20) 
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* L2TPv3 IP encapsulation support for IPv6
3 *
4 * Copyright (c) 2012 Katalix Systems Ltd
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/icmp.h>
10#include <linux/module.h>
11#include <linux/skbuff.h>
12#include <linux/random.h>
13#include <linux/socket.h>
14#include <linux/l2tp.h>
15#include <linux/in.h>
16#include <linux/in6.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 <net/transp_v6.h>
27#include <net/addrconf.h>
28#include <net/ip6_route.h>
29
30#include "l2tp_core.h"
31
32struct l2tp_ip6_sock {
33	/* inet_sock has to be the first member of l2tp_ip6_sock */
34	struct inet_sock	inet;
35
36	u32			conn_id;
37	u32			peer_conn_id;
38
39	/* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
40	 * inet6_sk_generic
41	 */
42	struct ipv6_pinfo	inet6;
43};
44
45static DEFINE_RWLOCK(l2tp_ip6_lock);
46static struct hlist_head l2tp_ip6_table;
47static struct hlist_head l2tp_ip6_bind_table;
48
49static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
50{
51	return (struct l2tp_ip6_sock *)sk;
52}
53
54static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
55					   const struct in6_addr *laddr,
56					   const struct in6_addr *raddr,
57					   int dif, u32 tunnel_id)
58{
59	struct sock *sk;
60
61	sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
62		const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
63		const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
64		const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
65
66		if (!net_eq(sock_net(sk), net))
67			continue;
68
69		if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
70			continue;
71
72		if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
73		    !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
74			continue;
75
76		if (!ipv6_addr_any(sk_raddr) && raddr &&
77		    !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
78			continue;
79
80		if (l2tp->conn_id != tunnel_id)
81			continue;
82
83		goto found;
84	}
85
86	sk = NULL;
87found:
88	return sk;
89}
90
91/* When processing receive frames, there are two cases to
92 * consider. Data frames consist of a non-zero session-id and an
93 * optional cookie. Control frames consist of a regular L2TP header
94 * preceded by 32-bits of zeros.
95 *
96 * L2TPv3 Session 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 * |                           Session ID                          |
102 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
103 * |               Cookie (optional, maximum 64 bits)...
104 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
105 *                                                                 |
106 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
107 *
108 * L2TPv3 Control Message Header Over IP
109 *
110 *  0                   1                   2                   3
111 *  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
112 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
113 * |                      (32 bits of zeros)                       |
114 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
115 * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
116 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
117 * |                     Control Connection ID                     |
118 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
119 * |               Ns              |               Nr              |
120 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
121 *
122 * All control frames are passed to userspace.
123 */
124static int l2tp_ip6_recv(struct sk_buff *skb)
125{
126	struct net *net = dev_net(skb->dev);
127	struct sock *sk;
128	u32 session_id;
129	u32 tunnel_id;
130	unsigned char *ptr, *optr;
131	struct l2tp_session *session;
132	struct l2tp_tunnel *tunnel = NULL;
133	struct ipv6hdr *iph;
134
135	if (!pskb_may_pull(skb, 4))
136		goto discard;
137
138	/* Point to L2TP header */
139	optr = skb->data;
140	ptr = skb->data;
141	session_id = ntohl(*((__be32 *)ptr));
142	ptr += 4;
143
144	/* RFC3931: L2TP/IP packets have the first 4 bytes containing
145	 * the session_id. If it is 0, the packet is a L2TP control
146	 * frame and the session_id value can be discarded.
147	 */
148	if (session_id == 0) {
149		__skb_pull(skb, 4);
150		goto pass_up;
151	}
152
153	/* Ok, this is a data packet. Lookup the session. */
154	session = l2tp_session_get(net, session_id);
155	if (!session)
156		goto discard;
157
158	tunnel = session->tunnel;
159	if (!tunnel)
160		goto discard_sess;
161
162	if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
163		goto discard_sess;
164
165	l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
166	l2tp_session_dec_refcount(session);
167
168	return 0;
169
170pass_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	iph = ipv6_hdr(skb);
180
181	read_lock_bh(&l2tp_ip6_lock);
182	sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
183				    inet6_iif(skb), tunnel_id);
184	if (!sk) {
185		read_unlock_bh(&l2tp_ip6_lock);
186		goto discard;
187	}
188	sock_hold(sk);
189	read_unlock_bh(&l2tp_ip6_lock);
190
191	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
192		goto discard_put;
193
194	nf_reset_ct(skb);
195
196	return sk_receive_skb(sk, skb, 1);
197
198discard_sess:
199	l2tp_session_dec_refcount(session);
200	goto discard;
201
202discard_put:
203	sock_put(sk);
204
205discard:
206	kfree_skb(skb);
207	return 0;
208}
209
210static int l2tp_ip6_hash(struct sock *sk)
211{
212	if (sk_unhashed(sk)) {
213		write_lock_bh(&l2tp_ip6_lock);
214		sk_add_node(sk, &l2tp_ip6_table);
215		write_unlock_bh(&l2tp_ip6_lock);
216	}
217	return 0;
218}
219
220static void l2tp_ip6_unhash(struct sock *sk)
221{
222	if (sk_unhashed(sk))
223		return;
224	write_lock_bh(&l2tp_ip6_lock);
225	sk_del_node_init(sk);
226	write_unlock_bh(&l2tp_ip6_lock);
227}
228
229static int l2tp_ip6_open(struct sock *sk)
230{
231	/* Prevent autobind. We don't have ports. */
232	inet_sk(sk)->inet_num = IPPROTO_L2TP;
233
234	l2tp_ip6_hash(sk);
235	return 0;
236}
237
238static void l2tp_ip6_close(struct sock *sk, long timeout)
239{
240	write_lock_bh(&l2tp_ip6_lock);
241	hlist_del_init(&sk->sk_bind_node);
242	sk_del_node_init(sk);
243	write_unlock_bh(&l2tp_ip6_lock);
244
245	sk_common_release(sk);
246}
247
248static void l2tp_ip6_destroy_sock(struct sock *sk)
249{
250	struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
251
252	lock_sock(sk);
253	ip6_flush_pending_frames(sk);
254	release_sock(sk);
255
256	if (tunnel)
257		l2tp_tunnel_delete(tunnel);
258}
259
260static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
261{
262	struct inet_sock *inet = inet_sk(sk);
263	struct ipv6_pinfo *np = inet6_sk(sk);
264	struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *)uaddr;
265	struct net *net = sock_net(sk);
266	__be32 v4addr = 0;
267	int bound_dev_if;
268	int addr_type;
269	int err;
270
271	if (addr->l2tp_family != AF_INET6)
272		return -EINVAL;
273	if (addr_len < sizeof(*addr))
274		return -EINVAL;
275
276	addr_type = ipv6_addr_type(&addr->l2tp_addr);
277
278	/* l2tp_ip6 sockets are IPv6 only */
279	if (addr_type == IPV6_ADDR_MAPPED)
280		return -EADDRNOTAVAIL;
281
282	/* L2TP is point-point, not multicast */
283	if (addr_type & IPV6_ADDR_MULTICAST)
284		return -EADDRNOTAVAIL;
285
286	lock_sock(sk);
287
288	err = -EINVAL;
289	if (!sock_flag(sk, SOCK_ZAPPED))
290		goto out_unlock;
291
292	if (sk->sk_state != TCP_CLOSE)
293		goto out_unlock;
294
295	bound_dev_if = sk->sk_bound_dev_if;
296
297	/* Check if the address belongs to the host. */
298	rcu_read_lock();
299	if (addr_type != IPV6_ADDR_ANY) {
300		struct net_device *dev = NULL;
301
302		if (addr_type & IPV6_ADDR_LINKLOCAL) {
303			if (addr->l2tp_scope_id)
304				bound_dev_if = addr->l2tp_scope_id;
305
306			/* Binding to link-local address requires an
307			 * interface.
308			 */
309			if (!bound_dev_if)
310				goto out_unlock_rcu;
311
312			err = -ENODEV;
313			dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
314			if (!dev)
315				goto out_unlock_rcu;
316		}
317
318		/* ipv4 addr of the socket is invalid.  Only the
319		 * unspecified and mapped address have a v4 equivalent.
320		 */
321		v4addr = LOOPBACK4_IPV6;
322		err = -EADDRNOTAVAIL;
323		if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
324			goto out_unlock_rcu;
325	}
326	rcu_read_unlock();
327
328	write_lock_bh(&l2tp_ip6_lock);
329	if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
330				   addr->l2tp_conn_id)) {
331		write_unlock_bh(&l2tp_ip6_lock);
332		err = -EADDRINUSE;
333		goto out_unlock;
334	}
335
336	inet->inet_saddr = v4addr;
337	inet->inet_rcv_saddr = v4addr;
338	sk->sk_bound_dev_if = bound_dev_if;
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	sk_add_bind_node(sk, &l2tp_ip6_bind_table);
345	sk_del_node_init(sk);
346	write_unlock_bh(&l2tp_ip6_lock);
347
348	sock_reset_flag(sk, SOCK_ZAPPED);
349	release_sock(sk);
350	return 0;
351
352out_unlock_rcu:
353	rcu_read_unlock();
354out_unlock:
355	release_sock(sk);
356
357	return err;
358}
359
360static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
361			    int addr_len)
362{
363	struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
364	struct sockaddr_in6	*usin = (struct sockaddr_in6 *)uaddr;
365	struct in6_addr	*daddr;
366	int	addr_type;
367	int rc;
368
369	if (addr_len < sizeof(*lsa))
370		return -EINVAL;
371
372	if (usin->sin6_family != AF_INET6)
373		return -EINVAL;
374
375	addr_type = ipv6_addr_type(&usin->sin6_addr);
376	if (addr_type & IPV6_ADDR_MULTICAST)
377		return -EINVAL;
378
379	if (addr_type & IPV6_ADDR_MAPPED) {
380		daddr = &usin->sin6_addr;
381		if (ipv4_is_multicast(daddr->s6_addr32[3]))
382			return -EINVAL;
383	}
384
385	lock_sock(sk);
386
387	 /* Must bind first - autobinding does not work */
388	if (sock_flag(sk, SOCK_ZAPPED)) {
389		rc = -EINVAL;
390		goto out_sk;
391	}
392
393	rc = __ip6_datagram_connect(sk, uaddr, addr_len);
394	if (rc < 0)
395		goto out_sk;
396
397	l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
398
399	write_lock_bh(&l2tp_ip6_lock);
400	hlist_del_init(&sk->sk_bind_node);
401	sk_add_bind_node(sk, &l2tp_ip6_bind_table);
402	write_unlock_bh(&l2tp_ip6_lock);
403
404out_sk:
405	release_sock(sk);
406
407	return rc;
408}
409
410static int l2tp_ip6_disconnect(struct sock *sk, int flags)
411{
412	if (sock_flag(sk, SOCK_ZAPPED))
413		return 0;
414
415	return __udp_disconnect(sk, flags);
416}
417
418static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
419			    int peer)
420{
421	struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
422	struct sock *sk = sock->sk;
423	struct ipv6_pinfo *np = inet6_sk(sk);
424	struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
425
426	lsa->l2tp_family = AF_INET6;
427	lsa->l2tp_flowinfo = 0;
428	lsa->l2tp_scope_id = 0;
429	lsa->l2tp_unused = 0;
430	if (peer) {
431		if (!lsk->peer_conn_id)
432			return -ENOTCONN;
433		lsa->l2tp_conn_id = lsk->peer_conn_id;
434		lsa->l2tp_addr = sk->sk_v6_daddr;
435		if (np->sndflow)
436			lsa->l2tp_flowinfo = np->flow_label;
437	} else {
438		if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
439			lsa->l2tp_addr = np->saddr;
440		else
441			lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
442
443		lsa->l2tp_conn_id = lsk->conn_id;
444	}
445	if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
446		lsa->l2tp_scope_id = sk->sk_bound_dev_if;
447	return sizeof(*lsa);
448}
449
450static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
451{
452	int rc;
453
454	/* Charge it to the socket, dropping if the queue is full. */
455	rc = sock_queue_rcv_skb(sk, skb);
456	if (rc < 0)
457		goto drop;
458
459	return 0;
460
461drop:
462	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
463	kfree_skb(skb);
464	return -1;
465}
466
467static int l2tp_ip6_push_pending_frames(struct sock *sk)
468{
469	struct sk_buff *skb;
470	__be32 *transhdr = NULL;
471	int err = 0;
472
473	skb = skb_peek(&sk->sk_write_queue);
474	if (!skb)
475		goto out;
476
477	transhdr = (__be32 *)skb_transport_header(skb);
478	*transhdr = 0;
479
480	err = ip6_push_pending_frames(sk);
481
482out:
483	return err;
484}
485
486/* Userspace will call sendmsg() on the tunnel socket to send L2TP
487 * control frames.
488 */
489static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
490{
491	struct ipv6_txoptions opt_space;
492	DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
493	struct in6_addr *daddr, *final_p, final;
494	struct ipv6_pinfo *np = inet6_sk(sk);
495	struct ipv6_txoptions *opt_to_free = NULL;
496	struct ipv6_txoptions *opt = NULL;
497	struct ip6_flowlabel *flowlabel = NULL;
498	struct dst_entry *dst = NULL;
499	struct flowi6 fl6;
500	struct ipcm6_cookie ipc6;
501	int addr_len = msg->msg_namelen;
502	int transhdrlen = 4; /* zero session-id */
503	int ulen;
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 - transhdrlen)
510		return -EMSGSIZE;
511
512	/* Mirror BSD error message compatibility */
513	if (msg->msg_flags & MSG_OOB)
514		return -EOPNOTSUPP;
515
516	/* Get and verify the address */
517	memset(&fl6, 0, sizeof(fl6));
518
519	fl6.flowi6_mark = sk->sk_mark;
520	fl6.flowi6_uid = sk->sk_uid;
521
522	ipcm6_init(&ipc6);
523
524	if (lsa) {
525		if (addr_len < SIN6_LEN_RFC2133)
526			return -EINVAL;
527
528		if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
529			return -EAFNOSUPPORT;
530
531		daddr = &lsa->l2tp_addr;
532		if (np->sndflow) {
533			fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
534			if (fl6.flowlabel & IPV6_FLOWLABEL_MASK) {
535				flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
536				if (IS_ERR(flowlabel))
537					return -EINVAL;
538			}
539		}
540
541		/* Otherwise it will be difficult to maintain
542		 * sk->sk_dst_cache.
543		 */
544		if (sk->sk_state == TCP_ESTABLISHED &&
545		    ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
546			daddr = &sk->sk_v6_daddr;
547
548		if (addr_len >= sizeof(struct sockaddr_in6) &&
549		    lsa->l2tp_scope_id &&
550		    ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
551			fl6.flowi6_oif = lsa->l2tp_scope_id;
552	} else {
553		if (sk->sk_state != TCP_ESTABLISHED)
554			return -EDESTADDRREQ;
555
556		daddr = &sk->sk_v6_daddr;
557		fl6.flowlabel = np->flow_label;
558	}
559
560	if (fl6.flowi6_oif == 0)
561		fl6.flowi6_oif = sk->sk_bound_dev_if;
562
563	if (msg->msg_controllen) {
564		opt = &opt_space;
565		memset(opt, 0, sizeof(struct ipv6_txoptions));
566		opt->tot_len = sizeof(struct ipv6_txoptions);
567		ipc6.opt = opt;
568
569		err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
570		if (err < 0) {
571			fl6_sock_release(flowlabel);
572			return err;
573		}
574		if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
575			flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
576			if (IS_ERR(flowlabel))
577				return -EINVAL;
578		}
579		if (!(opt->opt_nflen | opt->opt_flen))
580			opt = NULL;
581	}
582
583	if (!opt) {
584		opt = txopt_get(np);
585		opt_to_free = opt;
586	}
587	if (flowlabel)
588		opt = fl6_merge_options(&opt_space, flowlabel, opt);
589	opt = ipv6_fixup_options(&opt_space, opt);
590	ipc6.opt = opt;
591
592	fl6.flowi6_proto = sk->sk_protocol;
593	if (!ipv6_addr_any(daddr))
594		fl6.daddr = *daddr;
595	else
596		fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
597	if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
598		fl6.saddr = np->saddr;
599
600	final_p = fl6_update_dst(&fl6, opt, &final);
601
602	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
603		fl6.flowi6_oif = np->mcast_oif;
604	else if (!fl6.flowi6_oif)
605		fl6.flowi6_oif = np->ucast_oif;
606
607	security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));
608
609	if (ipc6.tclass < 0)
610		ipc6.tclass = np->tclass;
611
612	fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
613
614	dst = ip6_dst_lookup_flow(sock_net(sk), 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.dontfrag < 0)
624		ipc6.dontfrag = np->dontfrag;
625
626	if (msg->msg_flags & MSG_CONFIRM)
627		goto do_confirm;
628
629back_from_confirm:
630	lock_sock(sk);
631	ulen = len + skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0;
632	err = ip6_append_data(sk, ip_generic_getfrag, msg,
633			      ulen, transhdrlen, &ipc6,
634			      &fl6, (struct rt6_info *)dst,
635			      msg->msg_flags);
636	if (err)
637		ip6_flush_pending_frames(sk);
638	else if (!(msg->msg_flags & MSG_MORE))
639		err = l2tp_ip6_push_pending_frames(sk);
640	release_sock(sk);
641done:
642	dst_release(dst);
643out:
644	fl6_sock_release(flowlabel);
645	txopt_put(opt_to_free);
646
647	return err < 0 ? err : len;
648
649do_confirm:
650	if (msg->msg_flags & MSG_PROBE)
651		dst_confirm_neigh(dst, &fl6.daddr);
652	if (!(msg->msg_flags & MSG_PROBE) || len)
653		goto back_from_confirm;
654	err = 0;
655	goto done;
656}
657
658static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
659			    int noblock, int flags, int *addr_len)
660{
661	struct ipv6_pinfo *np = inet6_sk(sk);
662	DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
663	size_t copied = 0;
664	int err = -EOPNOTSUPP;
665	struct sk_buff *skb;
666
667	if (flags & MSG_OOB)
668		goto out;
669
670	if (flags & MSG_ERRQUEUE)
671		return ipv6_recv_error(sk, msg, len, addr_len);
672
673	skb = skb_recv_datagram(sk, flags, noblock, &err);
674	if (!skb)
675		goto out;
676
677	copied = skb->len;
678	if (len < copied) {
679		msg->msg_flags |= MSG_TRUNC;
680		copied = len;
681	}
682
683	err = skb_copy_datagram_msg(skb, 0, msg, copied);
684	if (err)
685		goto done;
686
687	sock_recv_timestamp(msg, sk, skb);
688
689	/* Copy the address. */
690	if (lsa) {
691		lsa->l2tp_family = AF_INET6;
692		lsa->l2tp_unused = 0;
693		lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
694		lsa->l2tp_flowinfo = 0;
695		lsa->l2tp_scope_id = 0;
696		lsa->l2tp_conn_id = 0;
697		if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
698			lsa->l2tp_scope_id = inet6_iif(skb);
699		*addr_len = sizeof(*lsa);
700	}
701
702	if (np->rxopt.all)
703		ip6_datagram_recv_ctl(sk, msg, skb);
704
705	if (flags & MSG_TRUNC)
706		copied = skb->len;
707done:
708	skb_free_datagram(sk, skb);
709out:
710	return err ? err : copied;
711}
712
713static struct proto l2tp_ip6_prot = {
714	.name		   = "L2TP/IPv6",
715	.owner		   = THIS_MODULE,
716	.init		   = l2tp_ip6_open,
717	.close		   = l2tp_ip6_close,
718	.bind		   = l2tp_ip6_bind,
719	.connect	   = l2tp_ip6_connect,
720	.disconnect	   = l2tp_ip6_disconnect,
721	.ioctl		   = l2tp_ioctl,
722	.destroy	   = l2tp_ip6_destroy_sock,
723	.setsockopt	   = ipv6_setsockopt,
724	.getsockopt	   = ipv6_getsockopt,
725	.sendmsg	   = l2tp_ip6_sendmsg,
726	.recvmsg	   = l2tp_ip6_recvmsg,
727	.backlog_rcv	   = l2tp_ip6_backlog_recv,
728	.hash		   = l2tp_ip6_hash,
729	.unhash		   = l2tp_ip6_unhash,
730	.obj_size	   = sizeof(struct l2tp_ip6_sock),
731};
732
733static const struct proto_ops l2tp_ip6_ops = {
734	.family		   = PF_INET6,
735	.owner		   = THIS_MODULE,
736	.release	   = inet6_release,
737	.bind		   = inet6_bind,
738	.connect	   = inet_dgram_connect,
739	.socketpair	   = sock_no_socketpair,
740	.accept		   = sock_no_accept,
741	.getname	   = l2tp_ip6_getname,
742	.poll		   = datagram_poll,
743	.ioctl		   = inet6_ioctl,
744	.gettstamp	   = sock_gettstamp,
745	.listen		   = sock_no_listen,
746	.shutdown	   = inet_shutdown,
747	.setsockopt	   = sock_common_setsockopt,
748	.getsockopt	   = sock_common_getsockopt,
749	.sendmsg	   = inet_sendmsg,
750	.recvmsg	   = sock_common_recvmsg,
751	.mmap		   = sock_no_mmap,
752	.sendpage	   = sock_no_sendpage,
753#ifdef CONFIG_COMPAT
754	.compat_ioctl	   = inet6_compat_ioctl,
755#endif
756};
757
758static struct inet_protosw l2tp_ip6_protosw = {
759	.type		= SOCK_DGRAM,
760	.protocol	= IPPROTO_L2TP,
761	.prot		= &l2tp_ip6_prot,
762	.ops		= &l2tp_ip6_ops,
763};
764
765static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
766	.handler	= l2tp_ip6_recv,
767};
768
769static int __init l2tp_ip6_init(void)
770{
771	int err;
772
773	pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
774
775	err = proto_register(&l2tp_ip6_prot, 1);
776	if (err != 0)
777		goto out;
778
779	err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
780	if (err)
781		goto out1;
782
783	inet6_register_protosw(&l2tp_ip6_protosw);
784	return 0;
785
786out1:
787	proto_unregister(&l2tp_ip6_prot);
788out:
789	return err;
790}
791
792static void __exit l2tp_ip6_exit(void)
793{
794	inet6_unregister_protosw(&l2tp_ip6_protosw);
795	inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
796	proto_unregister(&l2tp_ip6_prot);
797}
798
799module_init(l2tp_ip6_init);
800module_exit(l2tp_ip6_exit);
801
802MODULE_LICENSE("GPL");
803MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
804MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
805MODULE_VERSION("1.0");
806
807/* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
808 * enums
809 */
810MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
811MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);
812