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	struct ipv6_pinfo	inet6;
40};
41
42static DEFINE_RWLOCK(l2tp_ip6_lock);
43static struct hlist_head l2tp_ip6_table;
44static struct hlist_head l2tp_ip6_bind_table;
45
46static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
47{
48	return (struct l2tp_ip6_sock *)sk;
49}
50
51static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
52					   const struct in6_addr *laddr,
53					   const struct in6_addr *raddr,
54					   int dif, u32 tunnel_id)
55{
56	struct sock *sk;
57
58	sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
59		const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
60		const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
61		const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
62		int bound_dev_if;
63
64		if (!net_eq(sock_net(sk), net))
65			continue;
66
67		bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
68		if (bound_dev_if && dif && bound_dev_if != dif)
69			continue;
70
71		if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
72		    !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
73			continue;
74
75		if (!ipv6_addr_any(sk_raddr) && raddr &&
76		    !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
77			continue;
78
79		if (l2tp->conn_id != tunnel_id)
80			continue;
81
82		goto found;
83	}
84
85	sk = NULL;
86found:
87	return sk;
88}
89
90/* When processing receive frames, there are two cases to
91 * consider. Data frames consist of a non-zero session-id and an
92 * optional cookie. Control frames consist of a regular L2TP header
93 * preceded by 32-bits of zeros.
94 *
95 * L2TPv3 Session Header Over IP
96 *
97 *  0                   1                   2                   3
98 *  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
99 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
100 * |                           Session ID                          |
101 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
102 * |               Cookie (optional, maximum 64 bits)...
103 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
104 *                                                                 |
105 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
106 *
107 * L2TPv3 Control Message Header Over IP
108 *
109 *  0                   1                   2                   3
110 *  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
111 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
112 * |                      (32 bits of zeros)                       |
113 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
114 * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
115 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
116 * |                     Control Connection ID                     |
117 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
118 * |               Ns              |               Nr              |
119 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
120 *
121 * All control frames are passed to userspace.
122 */
123static int l2tp_ip6_recv(struct sk_buff *skb)
124{
125	struct net *net = dev_net(skb->dev);
126	struct sock *sk;
127	u32 session_id;
128	u32 tunnel_id;
129	unsigned char *ptr, *optr;
130	struct l2tp_session *session;
131	struct l2tp_tunnel *tunnel = NULL;
132	struct ipv6hdr *iph;
133
134	if (!pskb_may_pull(skb, 4))
135		goto discard;
136
137	/* Point to L2TP header */
138	optr = skb->data;
139	ptr = skb->data;
140	session_id = ntohl(*((__be32 *)ptr));
141	ptr += 4;
142
143	/* RFC3931: L2TP/IP packets have the first 4 bytes containing
144	 * the session_id. If it is 0, the packet is a L2TP control
145	 * frame and the session_id value can be discarded.
146	 */
147	if (session_id == 0) {
148		__skb_pull(skb, 4);
149		goto pass_up;
150	}
151
152	/* Ok, this is a data packet. Lookup the session. */
153	session = l2tp_session_get(net, session_id);
154	if (!session)
155		goto discard;
156
157	tunnel = session->tunnel;
158	if (!tunnel)
159		goto discard_sess;
160
161	if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
162		goto discard_sess;
163
164	l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
165	l2tp_session_dec_refcount(session);
166
167	return 0;
168
169pass_up:
170	/* Get the tunnel_id from the L2TP header */
171	if (!pskb_may_pull(skb, 12))
172		goto discard;
173
174	if ((skb->data[0] & 0xc0) != 0xc0)
175		goto discard;
176
177	tunnel_id = ntohl(*(__be32 *)&skb->data[4]);
178	iph = ipv6_hdr(skb);
179
180	read_lock_bh(&l2tp_ip6_lock);
181	sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
182				    inet6_iif(skb), tunnel_id);
183	if (!sk) {
184		read_unlock_bh(&l2tp_ip6_lock);
185		goto discard;
186	}
187	sock_hold(sk);
188	read_unlock_bh(&l2tp_ip6_lock);
189
190	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
191		goto discard_put;
192
193	nf_reset_ct(skb);
194
195	return sk_receive_skb(sk, skb, 1);
196
197discard_sess:
198	l2tp_session_dec_refcount(session);
199	goto discard;
200
201discard_put:
202	sock_put(sk);
203
204discard:
205	kfree_skb(skb);
206	return 0;
207}
208
209static int l2tp_ip6_hash(struct sock *sk)
210{
211	if (sk_unhashed(sk)) {
212		write_lock_bh(&l2tp_ip6_lock);
213		sk_add_node(sk, &l2tp_ip6_table);
214		write_unlock_bh(&l2tp_ip6_lock);
215	}
216	return 0;
217}
218
219static void l2tp_ip6_unhash(struct sock *sk)
220{
221	if (sk_unhashed(sk))
222		return;
223	write_lock_bh(&l2tp_ip6_lock);
224	sk_del_node_init(sk);
225	write_unlock_bh(&l2tp_ip6_lock);
226}
227
228static int l2tp_ip6_open(struct sock *sk)
229{
230	/* Prevent autobind. We don't have ports. */
231	inet_sk(sk)->inet_num = IPPROTO_L2TP;
232
233	l2tp_ip6_hash(sk);
234	return 0;
235}
236
237static void l2tp_ip6_close(struct sock *sk, long timeout)
238{
239	write_lock_bh(&l2tp_ip6_lock);
240	hlist_del_init(&sk->sk_bind_node);
241	sk_del_node_init(sk);
242	write_unlock_bh(&l2tp_ip6_lock);
243
244	sk_common_release(sk);
245}
246
247static void l2tp_ip6_destroy_sock(struct sock *sk)
248{
249	struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
250
251	lock_sock(sk);
252	ip6_flush_pending_frames(sk);
253	release_sock(sk);
254
255	if (tunnel)
256		l2tp_tunnel_delete(tunnel);
257}
258
259static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
260{
261	struct inet_sock *inet = inet_sk(sk);
262	struct ipv6_pinfo *np = inet6_sk(sk);
263	struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *)uaddr;
264	struct net *net = sock_net(sk);
265	__be32 v4addr = 0;
266	int bound_dev_if;
267	int addr_type;
268	int err;
269
270	if (addr->l2tp_family != AF_INET6)
271		return -EINVAL;
272	if (addr_len < sizeof(*addr))
273		return -EINVAL;
274
275	addr_type = ipv6_addr_type(&addr->l2tp_addr);
276
277	/* l2tp_ip6 sockets are IPv6 only */
278	if (addr_type == IPV6_ADDR_MAPPED)
279		return -EADDRNOTAVAIL;
280
281	/* L2TP is point-point, not multicast */
282	if (addr_type & IPV6_ADDR_MULTICAST)
283		return -EADDRNOTAVAIL;
284
285	lock_sock(sk);
286
287	err = -EINVAL;
288	if (!sock_flag(sk, SOCK_ZAPPED))
289		goto out_unlock;
290
291	if (sk->sk_state != TCP_CLOSE)
292		goto out_unlock;
293
294	bound_dev_if = sk->sk_bound_dev_if;
295
296	/* Check if the address belongs to the host. */
297	rcu_read_lock();
298	if (addr_type != IPV6_ADDR_ANY) {
299		struct net_device *dev = NULL;
300
301		if (addr_type & IPV6_ADDR_LINKLOCAL) {
302			if (addr->l2tp_scope_id)
303				bound_dev_if = addr->l2tp_scope_id;
304
305			/* Binding to link-local address requires an
306			 * interface.
307			 */
308			if (!bound_dev_if)
309				goto out_unlock_rcu;
310
311			err = -ENODEV;
312			dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
313			if (!dev)
314				goto out_unlock_rcu;
315		}
316
317		/* ipv4 addr of the socket is invalid.  Only the
318		 * unspecified and mapped address have a v4 equivalent.
319		 */
320		v4addr = LOOPBACK4_IPV6;
321		err = -EADDRNOTAVAIL;
322		if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
323			goto out_unlock_rcu;
324	}
325	rcu_read_unlock();
326
327	write_lock_bh(&l2tp_ip6_lock);
328	if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
329				   addr->l2tp_conn_id)) {
330		write_unlock_bh(&l2tp_ip6_lock);
331		err = -EADDRINUSE;
332		goto out_unlock;
333	}
334
335	inet->inet_saddr = v4addr;
336	inet->inet_rcv_saddr = v4addr;
337	sk->sk_bound_dev_if = bound_dev_if;
338	sk->sk_v6_rcv_saddr = addr->l2tp_addr;
339	np->saddr = addr->l2tp_addr;
340
341	l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
342
343	sk_add_bind_node(sk, &l2tp_ip6_bind_table);
344	sk_del_node_init(sk);
345	write_unlock_bh(&l2tp_ip6_lock);
346
347	sock_reset_flag(sk, SOCK_ZAPPED);
348	release_sock(sk);
349	return 0;
350
351out_unlock_rcu:
352	rcu_read_unlock();
353out_unlock:
354	release_sock(sk);
355
356	return err;
357}
358
359static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
360			    int addr_len)
361{
362	struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
363	struct sockaddr_in6	*usin = (struct sockaddr_in6 *)uaddr;
364	struct in6_addr	*daddr;
365	int	addr_type;
366	int rc;
367
368	if (addr_len < sizeof(*lsa))
369		return -EINVAL;
370
371	if (usin->sin6_family != AF_INET6)
372		return -EINVAL;
373
374	addr_type = ipv6_addr_type(&usin->sin6_addr);
375	if (addr_type & IPV6_ADDR_MULTICAST)
376		return -EINVAL;
377
378	if (addr_type & IPV6_ADDR_MAPPED) {
379		daddr = &usin->sin6_addr;
380		if (ipv4_is_multicast(daddr->s6_addr32[3]))
381			return -EINVAL;
382	}
383
384	lock_sock(sk);
385
386	 /* Must bind first - autobinding does not work */
387	if (sock_flag(sk, SOCK_ZAPPED)) {
388		rc = -EINVAL;
389		goto out_sk;
390	}
391
392	rc = __ip6_datagram_connect(sk, uaddr, addr_len);
393	if (rc < 0)
394		goto out_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
403out_sk:
404	release_sock(sk);
405
406	return rc;
407}
408
409static int l2tp_ip6_disconnect(struct sock *sk, int flags)
410{
411	if (sock_flag(sk, SOCK_ZAPPED))
412		return 0;
413
414	return __udp_disconnect(sk, flags);
415}
416
417static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
418			    int peer)
419{
420	struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
421	struct sock *sk = sock->sk;
422	struct ipv6_pinfo *np = inet6_sk(sk);
423	struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
424
425	lsa->l2tp_family = AF_INET6;
426	lsa->l2tp_flowinfo = 0;
427	lsa->l2tp_scope_id = 0;
428	lsa->l2tp_unused = 0;
429	if (peer) {
430		if (!lsk->peer_conn_id)
431			return -ENOTCONN;
432		lsa->l2tp_conn_id = lsk->peer_conn_id;
433		lsa->l2tp_addr = sk->sk_v6_daddr;
434		if (inet6_test_bit(SNDFLOW, sk))
435			lsa->l2tp_flowinfo = np->flow_label;
436	} else {
437		if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
438			lsa->l2tp_addr = np->saddr;
439		else
440			lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
441
442		lsa->l2tp_conn_id = lsk->conn_id;
443	}
444	if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
445		lsa->l2tp_scope_id = READ_ONCE(sk->sk_bound_dev_if);
446	return sizeof(*lsa);
447}
448
449static 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
460drop:
461	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
462	kfree_skb(skb);
463	return -1;
464}
465
466static 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)
474		goto out;
475
476	transhdr = (__be32 *)skb_transport_header(skb);
477	*transhdr = 0;
478
479	err = ip6_push_pending_frames(sk);
480
481out:
482	return err;
483}
484
485/* Userspace will call sendmsg() on the tunnel socket to send L2TP
486 * control frames.
487 */
488static 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 ipcm6_cookie ipc6;
500	int addr_len = msg->msg_namelen;
501	int transhdrlen = 4; /* zero session-id */
502	int ulen;
503	int err;
504
505	/* Rough check on arithmetic overflow,
506	 * better check is made in ip6_append_data().
507	 */
508	if (len > INT_MAX - transhdrlen)
509		return -EMSGSIZE;
510
511	/* Mirror BSD error message compatibility */
512	if (msg->msg_flags & MSG_OOB)
513		return -EOPNOTSUPP;
514
515	/* Get and verify the address */
516	memset(&fl6, 0, sizeof(fl6));
517
518	fl6.flowi6_mark = READ_ONCE(sk->sk_mark);
519	fl6.flowi6_uid = sk->sk_uid;
520
521	ipcm6_init(&ipc6);
522
523	if (lsa) {
524		if (addr_len < SIN6_LEN_RFC2133)
525			return -EINVAL;
526
527		if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
528			return -EAFNOSUPPORT;
529
530		daddr = &lsa->l2tp_addr;
531		if (inet6_test_bit(SNDFLOW, sk)) {
532			fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
533			if (fl6.flowlabel & IPV6_FLOWLABEL_MASK) {
534				flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
535				if (IS_ERR(flowlabel))
536					return -EINVAL;
537			}
538		}
539
540		/* Otherwise it will be difficult to maintain
541		 * sk->sk_dst_cache.
542		 */
543		if (sk->sk_state == TCP_ESTABLISHED &&
544		    ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
545			daddr = &sk->sk_v6_daddr;
546
547		if (addr_len >= sizeof(struct sockaddr_in6) &&
548		    lsa->l2tp_scope_id &&
549		    ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
550			fl6.flowi6_oif = lsa->l2tp_scope_id;
551	} else {
552		if (sk->sk_state != TCP_ESTABLISHED)
553			return -EDESTADDRREQ;
554
555		daddr = &sk->sk_v6_daddr;
556		fl6.flowlabel = np->flow_label;
557	}
558
559	if (fl6.flowi6_oif == 0)
560		fl6.flowi6_oif = READ_ONCE(sk->sk_bound_dev_if);
561
562	if (msg->msg_controllen) {
563		opt = &opt_space;
564		memset(opt, 0, sizeof(struct ipv6_txoptions));
565		opt->tot_len = sizeof(struct ipv6_txoptions);
566		ipc6.opt = opt;
567
568		err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
569		if (err < 0) {
570			fl6_sock_release(flowlabel);
571			return err;
572		}
573		if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
574			flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
575			if (IS_ERR(flowlabel))
576				return -EINVAL;
577		}
578		if (!(opt->opt_nflen | opt->opt_flen))
579			opt = NULL;
580	}
581
582	if (!opt) {
583		opt = txopt_get(np);
584		opt_to_free = opt;
585	}
586	if (flowlabel)
587		opt = fl6_merge_options(&opt_space, flowlabel, opt);
588	opt = ipv6_fixup_options(&opt_space, opt);
589	ipc6.opt = opt;
590
591	fl6.flowi6_proto = sk->sk_protocol;
592	if (!ipv6_addr_any(daddr))
593		fl6.daddr = *daddr;
594	else
595		fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
596	if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
597		fl6.saddr = np->saddr;
598
599	final_p = fl6_update_dst(&fl6, opt, &final);
600
601	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
602		fl6.flowi6_oif = READ_ONCE(np->mcast_oif);
603	else if (!fl6.flowi6_oif)
604		fl6.flowi6_oif = READ_ONCE(np->ucast_oif);
605
606	security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));
607
608	if (ipc6.tclass < 0)
609		ipc6.tclass = np->tclass;
610
611	fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
612
613	dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
614	if (IS_ERR(dst)) {
615		err = PTR_ERR(dst);
616		goto out;
617	}
618
619	if (ipc6.hlimit < 0)
620		ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
621
622	if (ipc6.dontfrag < 0)
623		ipc6.dontfrag = inet6_test_bit(DONTFRAG, sk);
624
625	if (msg->msg_flags & MSG_CONFIRM)
626		goto do_confirm;
627
628back_from_confirm:
629	lock_sock(sk);
630	ulen = len + (skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0);
631	err = ip6_append_data(sk, ip_generic_getfrag, msg,
632			      ulen, transhdrlen, &ipc6,
633			      &fl6, (struct rt6_info *)dst,
634			      msg->msg_flags);
635	if (err)
636		ip6_flush_pending_frames(sk);
637	else if (!(msg->msg_flags & MSG_MORE))
638		err = l2tp_ip6_push_pending_frames(sk);
639	release_sock(sk);
640done:
641	dst_release(dst);
642out:
643	fl6_sock_release(flowlabel);
644	txopt_put(opt_to_free);
645
646	return err < 0 ? err : len;
647
648do_confirm:
649	if (msg->msg_flags & MSG_PROBE)
650		dst_confirm_neigh(dst, &fl6.daddr);
651	if (!(msg->msg_flags & MSG_PROBE) || len)
652		goto back_from_confirm;
653	err = 0;
654	goto done;
655}
656
657static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
658			    int flags, int *addr_len)
659{
660	struct ipv6_pinfo *np = inet6_sk(sk);
661	DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
662	size_t copied = 0;
663	int err = -EOPNOTSUPP;
664	struct sk_buff *skb;
665
666	if (flags & MSG_OOB)
667		goto out;
668
669	if (flags & MSG_ERRQUEUE)
670		return ipv6_recv_error(sk, msg, len, addr_len);
671
672	skb = skb_recv_datagram(sk, flags, &err);
673	if (!skb)
674		goto out;
675
676	copied = skb->len;
677	if (len < copied) {
678		msg->msg_flags |= MSG_TRUNC;
679		copied = len;
680	}
681
682	err = skb_copy_datagram_msg(skb, 0, msg, copied);
683	if (err)
684		goto done;
685
686	sock_recv_timestamp(msg, sk, skb);
687
688	/* Copy the address. */
689	if (lsa) {
690		lsa->l2tp_family = AF_INET6;
691		lsa->l2tp_unused = 0;
692		lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
693		lsa->l2tp_flowinfo = 0;
694		lsa->l2tp_scope_id = 0;
695		lsa->l2tp_conn_id = 0;
696		if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
697			lsa->l2tp_scope_id = inet6_iif(skb);
698		*addr_len = sizeof(*lsa);
699	}
700
701	if (np->rxopt.all)
702		ip6_datagram_recv_ctl(sk, msg, skb);
703
704	if (flags & MSG_TRUNC)
705		copied = skb->len;
706done:
707	skb_free_datagram(sk, skb);
708out:
709	return err ? err : copied;
710}
711
712static struct proto l2tp_ip6_prot = {
713	.name		   = "L2TP/IPv6",
714	.owner		   = THIS_MODULE,
715	.init		   = l2tp_ip6_open,
716	.close		   = l2tp_ip6_close,
717	.bind		   = l2tp_ip6_bind,
718	.connect	   = l2tp_ip6_connect,
719	.disconnect	   = l2tp_ip6_disconnect,
720	.ioctl		   = l2tp_ioctl,
721	.destroy	   = l2tp_ip6_destroy_sock,
722	.setsockopt	   = ipv6_setsockopt,
723	.getsockopt	   = ipv6_getsockopt,
724	.sendmsg	   = l2tp_ip6_sendmsg,
725	.recvmsg	   = l2tp_ip6_recvmsg,
726	.backlog_rcv	   = l2tp_ip6_backlog_recv,
727	.hash		   = l2tp_ip6_hash,
728	.unhash		   = l2tp_ip6_unhash,
729	.obj_size	   = sizeof(struct l2tp_ip6_sock),
730	.ipv6_pinfo_offset = offsetof(struct l2tp_ip6_sock, inet6),
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#ifdef CONFIG_COMPAT
753	.compat_ioctl	   = inet6_compat_ioctl,
754#endif
755};
756
757static struct inet_protosw l2tp_ip6_protosw = {
758	.type		= SOCK_DGRAM,
759	.protocol	= IPPROTO_L2TP,
760	.prot		= &l2tp_ip6_prot,
761	.ops		= &l2tp_ip6_ops,
762};
763
764static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
765	.handler	= l2tp_ip6_recv,
766};
767
768static int __init l2tp_ip6_init(void)
769{
770	int err;
771
772	pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
773
774	err = proto_register(&l2tp_ip6_prot, 1);
775	if (err != 0)
776		goto out;
777
778	err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
779	if (err)
780		goto out1;
781
782	inet6_register_protosw(&l2tp_ip6_protosw);
783	return 0;
784
785out1:
786	proto_unregister(&l2tp_ip6_prot);
787out:
788	return err;
789}
790
791static void __exit l2tp_ip6_exit(void)
792{
793	inet6_unregister_protosw(&l2tp_ip6_protosw);
794	inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
795	proto_unregister(&l2tp_ip6_prot);
796}
797
798module_init(l2tp_ip6_init);
799module_exit(l2tp_ip6_exit);
800
801MODULE_LICENSE("GPL");
802MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
803MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
804MODULE_VERSION("1.0");
805
806/* Use the values of SOCK_DGRAM (2) as type and IPPROTO_L2TP (115) as protocol,
807 * because __stringify doesn't like enums
808 */
809MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 115, 2);
810MODULE_ALIAS_NET_PF_PROTO(PF_INET6, 115);
811