l2tp_ip6.c

  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#include <net/net_namespace.h>
 26#include <net/netns/generic.h>
 27
 28#include <net/transp_v6.h>
 29#include <net/addrconf.h>
 30#include <net/ip6_route.h>
 31
 32#include "l2tp_core.h"
 33
 34/* per-net private data for this module */
 35static unsigned int l2tp_ip6_net_id;
 36struct l2tp_ip6_net {
 37	rwlock_t l2tp_ip6_lock;
 38	struct hlist_head l2tp_ip6_table;
 39	struct hlist_head l2tp_ip6_bind_table;
 40};
 41
 42struct l2tp_ip6_sock {
 43	/* inet_sock has to be the first member of l2tp_ip6_sock */
 44	struct inet_sock	inet;
 45
 46	u32			conn_id;
 47	u32			peer_conn_id;
 48
 49	struct ipv6_pinfo	inet6;
 50};
 51
 52static struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
 53{
 54	return (struct l2tp_ip6_sock *)sk;
 55}
 56
 57static struct l2tp_ip6_net *l2tp_ip6_pernet(const struct net *net)
 58{
 59	return net_generic(net, l2tp_ip6_net_id);
 60}
 61
 62static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
 63					   const struct in6_addr *laddr,
 64					   const struct in6_addr *raddr,
 65					   int dif, u32 tunnel_id)
 66{
 67	struct l2tp_ip6_net *pn = l2tp_ip6_pernet(net);
 68	struct sock *sk;
 69
 70	sk_for_each_bound(sk, &pn->l2tp_ip6_bind_table) {
 71		const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
 72		const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
 73		const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
 74		int bound_dev_if;
 75
 76		if (!net_eq(sock_net(sk), net))
 77			continue;
 78
 79		bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
 80		if (bound_dev_if && dif && bound_dev_if != dif)
 81			continue;
 82
 83		if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
 84		    !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
 85			continue;
 86
 87		if (!ipv6_addr_any(sk_raddr) && raddr &&
 88		    !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
 89			continue;
 90
 91		if (l2tp->conn_id != tunnel_id)
 92			continue;
 93
 94		goto found;
 95	}
 96
 97	sk = NULL;
 98found:
 99	return sk;
100}
101
102/* When processing receive frames, there are two cases to
103 * consider. Data frames consist of a non-zero session-id and an
104 * optional cookie. Control frames consist of a regular L2TP header
105 * preceded by 32-bits of zeros.
106 *
107 * L2TPv3 Session 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 * |                           Session ID                          |
113 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
114 * |               Cookie (optional, maximum 64 bits)...
115 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
116 *                                                                 |
117 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
118 *
119 * L2TPv3 Control Message Header Over IP
120 *
121 *  0                   1                   2                   3
122 *  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
123 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
124 * |                      (32 bits of zeros)                       |
125 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
126 * |T|L|x|x|S|x|x|x|x|x|x|x|  Ver  |             Length            |
127 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
128 * |                     Control Connection ID                     |
129 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
130 * |               Ns              |               Nr              |
131 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
132 *
133 * All control frames are passed to userspace.
134 */
135static int l2tp_ip6_recv(struct sk_buff *skb)
136{
137	struct net *net = dev_net(skb->dev);
138	struct l2tp_ip6_net *pn;
139	struct sock *sk;
140	u32 session_id;
141	u32 tunnel_id;
142	unsigned char *ptr, *optr;
143	struct l2tp_session *session;
144	struct l2tp_tunnel *tunnel = NULL;
145	struct ipv6hdr *iph;
146
147	pn = l2tp_ip6_pernet(net);
148
149	if (!pskb_may_pull(skb, 4))
150		goto discard;
151
152	/* Point to L2TP header */
153	optr = skb->data;
154	ptr = skb->data;
155	session_id = ntohl(*((__be32 *)ptr));
156	ptr += 4;
157
158	/* RFC3931: L2TP/IP packets have the first 4 bytes containing
159	 * the session_id. If it is 0, the packet is a L2TP control
160	 * frame and the session_id value can be discarded.
161	 */
162	if (session_id == 0) {
163		__skb_pull(skb, 4);
164		goto pass_up;
165	}
166
167	/* Ok, this is a data packet. Lookup the session. */
168	session = l2tp_v3_session_get(net, NULL, session_id);
169	if (!session)
170		goto discard;
171
172	tunnel = session->tunnel;
173	if (!tunnel)
174		goto discard_sess;
175
176	if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
177		goto discard_sess;
178
179	l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
180	l2tp_session_put(session);
181
182	return 0;
183
184pass_up:
185	/* Get the tunnel_id from the L2TP header */
186	if (!pskb_may_pull(skb, 12))
187		goto discard;
188
189	if ((skb->data[0] & 0xc0) != 0xc0)
190		goto discard;
191
192	tunnel_id = ntohl(*(__be32 *)&skb->data[4]);
193	iph = ipv6_hdr(skb);
194
195	read_lock_bh(&pn->l2tp_ip6_lock);
196	sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
197				    inet6_iif(skb), tunnel_id);
198	if (!sk) {
199		read_unlock_bh(&pn->l2tp_ip6_lock);
200		goto discard;
201	}
202	sock_hold(sk);
203	read_unlock_bh(&pn->l2tp_ip6_lock);
204
205	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
206		goto discard_put;
207
208	nf_reset_ct(skb);
209
210	return sk_receive_skb(sk, skb, 1);
211
212discard_sess:
213	l2tp_session_put(session);
214	goto discard;
215
216discard_put:
217	sock_put(sk);
218
219discard:
220	kfree_skb(skb);
221	return 0;
222}
223
224static int l2tp_ip6_hash(struct sock *sk)
225{
226	struct l2tp_ip6_net *pn = l2tp_ip6_pernet(sock_net(sk));
227
228	if (sk_unhashed(sk)) {
229		write_lock_bh(&pn->l2tp_ip6_lock);
230		sk_add_node(sk, &pn->l2tp_ip6_table);
231		write_unlock_bh(&pn->l2tp_ip6_lock);
232	}
233	return 0;
234}
235
236static void l2tp_ip6_unhash(struct sock *sk)
237{
238	struct l2tp_ip6_net *pn = l2tp_ip6_pernet(sock_net(sk));
239
240	if (sk_unhashed(sk))
241		return;
242	write_lock_bh(&pn->l2tp_ip6_lock);
243	sk_del_node_init(sk);
244	write_unlock_bh(&pn->l2tp_ip6_lock);
245}
246
247static int l2tp_ip6_open(struct sock *sk)
248{
249	/* Prevent autobind. We don't have ports. */
250	inet_sk(sk)->inet_num = IPPROTO_L2TP;
251
252	l2tp_ip6_hash(sk);
253	return 0;
254}
255
256static void l2tp_ip6_close(struct sock *sk, long timeout)
257{
258	struct l2tp_ip6_net *pn = l2tp_ip6_pernet(sock_net(sk));
259
260	write_lock_bh(&pn->l2tp_ip6_lock);
261	hlist_del_init(&sk->sk_bind_node);
262	sk_del_node_init(sk);
263	write_unlock_bh(&pn->l2tp_ip6_lock);
264
265	sk_common_release(sk);
266}
267
268static void l2tp_ip6_destroy_sock(struct sock *sk)
269{
270	struct l2tp_tunnel *tunnel;
271
272	lock_sock(sk);
273	ip6_flush_pending_frames(sk);
274	release_sock(sk);
275
276	tunnel = l2tp_sk_to_tunnel(sk);
277	if (tunnel) {
278		l2tp_tunnel_delete(tunnel);
279		l2tp_tunnel_put(tunnel);
280	}
281}
282
283static int l2tp_ip6_bind(struct sock *sk, struct sockaddr_unsized *uaddr,
284			 int addr_len)
285{
286	struct inet_sock *inet = inet_sk(sk);
287	struct ipv6_pinfo *np = inet6_sk(sk);
288	struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *)uaddr;
289	struct net *net = sock_net(sk);
290	struct l2tp_ip6_net *pn;
291	__be32 v4addr = 0;
292	int bound_dev_if;
293	int addr_type;
294	int err;
295
296	pn = l2tp_ip6_pernet(net);
297
298	if (addr->l2tp_family != AF_INET6)
299		return -EINVAL;
300	if (addr_len < sizeof(*addr))
301		return -EINVAL;
302
303	addr_type = ipv6_addr_type(&addr->l2tp_addr);
304
305	/* l2tp_ip6 sockets are IPv6 only */
306	if (addr_type == IPV6_ADDR_MAPPED)
307		return -EADDRNOTAVAIL;
308
309	/* L2TP is point-point, not multicast */
310	if (addr_type & IPV6_ADDR_MULTICAST)
311		return -EADDRNOTAVAIL;
312
313	lock_sock(sk);
314
315	err = -EINVAL;
316	if (!sock_flag(sk, SOCK_ZAPPED))
317		goto out_unlock;
318
319	if (sk->sk_state != TCP_CLOSE)
320		goto out_unlock;
321
322	bound_dev_if = sk->sk_bound_dev_if;
323
324	/* Check if the address belongs to the host. */
325	rcu_read_lock();
326	if (addr_type != IPV6_ADDR_ANY) {
327		struct net_device *dev = NULL;
328
329		if (addr_type & IPV6_ADDR_LINKLOCAL) {
330			if (addr->l2tp_scope_id)
331				bound_dev_if = addr->l2tp_scope_id;
332
333			/* Binding to link-local address requires an
334			 * interface.
335			 */
336			if (!bound_dev_if)
337				goto out_unlock_rcu;
338
339			err = -ENODEV;
340			dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
341			if (!dev)
342				goto out_unlock_rcu;
343		}
344
345		/* ipv4 addr of the socket is invalid.  Only the
346		 * unspecified and mapped address have a v4 equivalent.
347		 */
348		v4addr = LOOPBACK4_IPV6;
349		err = -EADDRNOTAVAIL;
350		if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
351			goto out_unlock_rcu;
352	}
353	rcu_read_unlock();
354
355	write_lock_bh(&pn->l2tp_ip6_lock);
356	if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
357				   addr->l2tp_conn_id)) {
358		write_unlock_bh(&pn->l2tp_ip6_lock);
359		err = -EADDRINUSE;
360		goto out_unlock;
361	}
362
363	inet->inet_saddr = v4addr;
364	inet->inet_rcv_saddr = v4addr;
365	sk->sk_bound_dev_if = bound_dev_if;
366	sk->sk_v6_rcv_saddr = addr->l2tp_addr;
367	np->saddr = addr->l2tp_addr;
368
369	l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
370
371	sk_add_bind_node(sk, &pn->l2tp_ip6_bind_table);
372	sk_del_node_init(sk);
373	write_unlock_bh(&pn->l2tp_ip6_lock);
374
375	sock_reset_flag(sk, SOCK_ZAPPED);
376	release_sock(sk);
377	return 0;
378
379out_unlock_rcu:
380	rcu_read_unlock();
381out_unlock:
382	release_sock(sk);
383
384	return err;
385}
386
387static int l2tp_ip6_connect(struct sock *sk, struct sockaddr_unsized *uaddr,
388			    int addr_len)
389{
390	struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
391	struct sockaddr_in6	*usin = (struct sockaddr_in6 *)uaddr;
392	struct in6_addr	*daddr;
393	int	addr_type;
394	int rc;
395	struct l2tp_ip6_net *pn;
396
397	if (addr_len < sizeof(*lsa))
398		return -EINVAL;
399
400	if (usin->sin6_family != AF_INET6)
401		return -EINVAL;
402
403	addr_type = ipv6_addr_type(&usin->sin6_addr);
404	if (addr_type & IPV6_ADDR_MULTICAST)
405		return -EINVAL;
406
407	if (addr_type & IPV6_ADDR_MAPPED) {
408		daddr = &usin->sin6_addr;
409		if (ipv4_is_multicast(daddr->s6_addr32[3]))
410			return -EINVAL;
411	}
412
413	lock_sock(sk);
414
415	 /* Must bind first - autobinding does not work */
416	if (sock_flag(sk, SOCK_ZAPPED)) {
417		rc = -EINVAL;
418		goto out_sk;
419	}
420
421	rc = __ip6_datagram_connect(sk, uaddr, addr_len);
422	if (rc < 0)
423		goto out_sk;
424
425	l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
426
427	pn = l2tp_ip6_pernet(sock_net(sk));
428	write_lock_bh(&pn->l2tp_ip6_lock);
429	hlist_del_init(&sk->sk_bind_node);
430	sk_add_bind_node(sk, &pn->l2tp_ip6_bind_table);
431	write_unlock_bh(&pn->l2tp_ip6_lock);
432
433out_sk:
434	release_sock(sk);
435
436	return rc;
437}
438
439static int l2tp_ip6_disconnect(struct sock *sk, int flags)
440{
441	if (sock_flag(sk, SOCK_ZAPPED))
442		return 0;
443
444	return __udp_disconnect(sk, flags);
445}
446
447static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
448			    int peer)
449{
450	struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
451	struct sock *sk = sock->sk;
452	struct ipv6_pinfo *np = inet6_sk(sk);
453	struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
454
455	lsa->l2tp_family = AF_INET6;
456	lsa->l2tp_flowinfo = 0;
457	lsa->l2tp_scope_id = 0;
458	lsa->l2tp_unused = 0;
459	if (peer) {
460		if (!lsk->peer_conn_id)
461			return -ENOTCONN;
462		lsa->l2tp_conn_id = lsk->peer_conn_id;
463		lsa->l2tp_addr = sk->sk_v6_daddr;
464		if (inet6_test_bit(SNDFLOW, sk))
465			lsa->l2tp_flowinfo = np->flow_label;
466	} else {
467		if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
468			lsa->l2tp_addr = np->saddr;
469		else
470			lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
471
472		lsa->l2tp_conn_id = lsk->conn_id;
473	}
474	if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
475		lsa->l2tp_scope_id = READ_ONCE(sk->sk_bound_dev_if);
476	return sizeof(*lsa);
477}
478
479static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
480{
481	int rc;
482
483	/* Charge it to the socket, dropping if the queue is full. */
484	rc = sock_queue_rcv_skb(sk, skb);
485	if (rc < 0)
486		goto drop;
487
488	return 0;
489
490drop:
491	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
492	kfree_skb(skb);
493	return -1;
494}
495
496static int l2tp_ip6_push_pending_frames(struct sock *sk)
497{
498	struct sk_buff *skb;
499	__be32 *transhdr = NULL;
500	int err = 0;
501
502	skb = skb_peek(&sk->sk_write_queue);
503	if (!skb)
504		goto out;
505
506	transhdr = (__be32 *)skb_transport_header(skb);
507	*transhdr = 0;
508
509	err = ip6_push_pending_frames(sk);
510
511out:
512	return err;
513}
514
515/* Userspace will call sendmsg() on the tunnel socket to send L2TP
516 * control frames.
517 */
518static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
519{
520	struct ipv6_txoptions opt_space;
521	DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
522	struct in6_addr *daddr, *final_p, final;
523	struct ipv6_pinfo *np = inet6_sk(sk);
524	struct ipv6_txoptions *opt_to_free = NULL;
525	struct ipv6_txoptions *opt = NULL;
526	struct ip6_flowlabel *flowlabel = NULL;
527	struct dst_entry *dst = NULL;
528	struct flowi6 fl6;
529	struct ipcm6_cookie ipc6;
530	int addr_len = msg->msg_namelen;
531	int transhdrlen = 4; /* zero session-id */
532	int ulen;
533	int err;
534
535	/* Rough check on arithmetic overflow,
536	 * better check is made in ip6_append_data().
537	 */
538	if (len > INT_MAX - transhdrlen)
539		return -EMSGSIZE;
540
541	/* Mirror BSD error message compatibility */
542	if (msg->msg_flags & MSG_OOB)
543		return -EOPNOTSUPP;
544
545	/* Get and verify the address */
546	memset(&fl6, 0, sizeof(fl6));
547
548	fl6.flowi6_mark = READ_ONCE(sk->sk_mark);
549	fl6.flowi6_uid = sk_uid(sk);
550
551	ipcm6_init_sk(&ipc6, sk);
552
553	if (lsa) {
554		if (addr_len < SIN6_LEN_RFC2133)
555			return -EINVAL;
556
557		if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
558			return -EAFNOSUPPORT;
559
560		daddr = &lsa->l2tp_addr;
561		if (inet6_test_bit(SNDFLOW, sk)) {
562			fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
563			if (fl6.flowlabel & IPV6_FLOWLABEL_MASK) {
564				flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
565				if (IS_ERR(flowlabel))
566					return -EINVAL;
567			}
568		}
569
570		/* Otherwise it will be difficult to maintain
571		 * sk->sk_dst_cache.
572		 */
573		if (sk->sk_state == TCP_ESTABLISHED &&
574		    ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
575			daddr = &sk->sk_v6_daddr;
576
577		if (addr_len >= sizeof(struct sockaddr_in6) &&
578		    lsa->l2tp_scope_id &&
579		    ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
580			fl6.flowi6_oif = lsa->l2tp_scope_id;
581	} else {
582		if (sk->sk_state != TCP_ESTABLISHED)
583			return -EDESTADDRREQ;
584
585		daddr = &sk->sk_v6_daddr;
586		fl6.flowlabel = np->flow_label;
587	}
588
589	if (fl6.flowi6_oif == 0)
590		fl6.flowi6_oif = READ_ONCE(sk->sk_bound_dev_if);
591
592	if (msg->msg_controllen) {
593		opt = &opt_space;
594		memset(opt, 0, sizeof(struct ipv6_txoptions));
595		opt->tot_len = sizeof(struct ipv6_txoptions);
596		ipc6.opt = opt;
597
598		err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
599		if (err < 0) {
600			fl6_sock_release(flowlabel);
601			return err;
602		}
603		if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
604			flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
605			if (IS_ERR(flowlabel))
606				return -EINVAL;
607		}
608		if (!(opt->opt_nflen | opt->opt_flen))
609			opt = NULL;
610	}
611
612	if (!opt) {
613		opt = txopt_get(np);
614		opt_to_free = opt;
615	}
616	if (flowlabel)
617		opt = fl6_merge_options(&opt_space, flowlabel, opt);
618	opt = ipv6_fixup_options(&opt_space, opt);
619	ipc6.opt = opt;
620
621	fl6.flowi6_proto = sk->sk_protocol;
622	if (!ipv6_addr_any(daddr))
623		fl6.daddr = *daddr;
624	else
625		fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
626	if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
627		fl6.saddr = np->saddr;
628
629	final_p = fl6_update_dst(&fl6, opt, &final);
630
631	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
632		fl6.flowi6_oif = READ_ONCE(np->mcast_oif);
633	else if (!fl6.flowi6_oif)
634		fl6.flowi6_oif = READ_ONCE(np->ucast_oif);
635
636	security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));
637
638	fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
639
640	dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
641	if (IS_ERR(dst)) {
642		err = PTR_ERR(dst);
643		goto out;
644	}
645
646	if (ipc6.hlimit < 0)
647		ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
648
649	if (msg->msg_flags & MSG_CONFIRM)
650		goto do_confirm;
651
652back_from_confirm:
653	lock_sock(sk);
654	ulen = len + (skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0);
655	err = ip6_append_data(sk, ip_generic_getfrag, msg,
656			      ulen, transhdrlen, &ipc6,
657			      &fl6, dst_rt6_info(dst),
658			      msg->msg_flags);
659	if (err)
660		ip6_flush_pending_frames(sk);
661	else if (!(msg->msg_flags & MSG_MORE))
662		err = l2tp_ip6_push_pending_frames(sk);
663	release_sock(sk);
664done:
665	dst_release(dst);
666out:
667	fl6_sock_release(flowlabel);
668	txopt_put(opt_to_free);
669
670	return err < 0 ? err : len;
671
672do_confirm:
673	if (msg->msg_flags & MSG_PROBE)
674		dst_confirm_neigh(dst, &fl6.daddr);
675	if (!(msg->msg_flags & MSG_PROBE) || len)
676		goto back_from_confirm;
677	err = 0;
678	goto done;
679}
680
681static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
682			    int flags, int *addr_len)
683{
684	struct ipv6_pinfo *np = inet6_sk(sk);
685	DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
686	size_t copied = 0;
687	int err = -EOPNOTSUPP;
688	struct sk_buff *skb;
689
690	if (flags & MSG_OOB)
691		goto out;
692
693	if (flags & MSG_ERRQUEUE)
694		return ipv6_recv_error(sk, msg, len, addr_len);
695
696	skb = skb_recv_datagram(sk, flags, &err);
697	if (!skb)
698		goto out;
699
700	copied = skb->len;
701	if (len < copied) {
702		msg->msg_flags |= MSG_TRUNC;
703		copied = len;
704	}
705
706	err = skb_copy_datagram_msg(skb, 0, msg, copied);
707	if (err)
708		goto done;
709
710	sock_recv_timestamp(msg, sk, skb);
711
712	/* Copy the address. */
713	if (lsa) {
714		lsa->l2tp_family = AF_INET6;
715		lsa->l2tp_unused = 0;
716		lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
717		lsa->l2tp_flowinfo = 0;
718		lsa->l2tp_scope_id = 0;
719		lsa->l2tp_conn_id = 0;
720		if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
721			lsa->l2tp_scope_id = inet6_iif(skb);
722		*addr_len = sizeof(*lsa);
723	}
724
725	if (np->rxopt.all)
726		ip6_datagram_recv_ctl(sk, msg, skb);
727
728	if (flags & MSG_TRUNC)
729		copied = skb->len;
730done:
731	skb_free_datagram(sk, skb);
732out:
733	return err ? err : copied;
734}
735
736static struct proto l2tp_ip6_prot = {
737	.name		   = "L2TP/IPv6",
738	.owner		   = THIS_MODULE,
739	.init		   = l2tp_ip6_open,
740	.close		   = l2tp_ip6_close,
741	.bind		   = l2tp_ip6_bind,
742	.connect	   = l2tp_ip6_connect,
743	.disconnect	   = l2tp_ip6_disconnect,
744	.ioctl		   = l2tp_ioctl,
745	.destroy	   = l2tp_ip6_destroy_sock,
746	.setsockopt	   = ipv6_setsockopt,
747	.getsockopt	   = ipv6_getsockopt,
748	.sendmsg	   = l2tp_ip6_sendmsg,
749	.recvmsg	   = l2tp_ip6_recvmsg,
750	.backlog_rcv	   = l2tp_ip6_backlog_recv,
751	.hash		   = l2tp_ip6_hash,
752	.unhash		   = l2tp_ip6_unhash,
753	.obj_size	   = sizeof(struct l2tp_ip6_sock),
754	.ipv6_pinfo_offset = offsetof(struct l2tp_ip6_sock, inet6),
755};
756
757static const struct proto_ops l2tp_ip6_ops = {
758	.family		   = PF_INET6,
759	.owner		   = THIS_MODULE,
760	.release	   = inet6_release,
761	.bind		   = inet6_bind,
762	.connect	   = inet_dgram_connect,
763	.socketpair	   = sock_no_socketpair,
764	.accept		   = sock_no_accept,
765	.getname	   = l2tp_ip6_getname,
766	.poll		   = datagram_poll,
767	.ioctl		   = inet6_ioctl,
768	.gettstamp	   = sock_gettstamp,
769	.listen		   = sock_no_listen,
770	.shutdown	   = inet_shutdown,
771	.setsockopt	   = sock_common_setsockopt,
772	.getsockopt	   = sock_common_getsockopt,
773	.sendmsg	   = inet_sendmsg,
774	.recvmsg	   = sock_common_recvmsg,
775	.mmap		   = sock_no_mmap,
776#ifdef CONFIG_COMPAT
777	.compat_ioctl	   = inet6_compat_ioctl,
778#endif
779};
780
781static struct inet_protosw l2tp_ip6_protosw = {
782	.type		= SOCK_DGRAM,
783	.protocol	= IPPROTO_L2TP,
784	.prot		= &l2tp_ip6_prot,
785	.ops		= &l2tp_ip6_ops,
786};
787
788static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
789	.handler	= l2tp_ip6_recv,
790};
791
792static __net_init int l2tp_ip6_init_net(struct net *net)
793{
794	struct l2tp_ip6_net *pn = net_generic(net, l2tp_ip6_net_id);
795
796	rwlock_init(&pn->l2tp_ip6_lock);
797	INIT_HLIST_HEAD(&pn->l2tp_ip6_table);
798	INIT_HLIST_HEAD(&pn->l2tp_ip6_bind_table);
799	return 0;
800}
801
802static __net_exit void l2tp_ip6_exit_net(struct net *net)
803{
804	struct l2tp_ip6_net *pn = l2tp_ip6_pernet(net);
805
806	write_lock_bh(&pn->l2tp_ip6_lock);
807	WARN_ON_ONCE(hlist_count_nodes(&pn->l2tp_ip6_table) != 0);
808	WARN_ON_ONCE(hlist_count_nodes(&pn->l2tp_ip6_bind_table) != 0);
809	write_unlock_bh(&pn->l2tp_ip6_lock);
810}
811
812static struct pernet_operations l2tp_ip6_net_ops = {
813	.init = l2tp_ip6_init_net,
814	.exit = l2tp_ip6_exit_net,
815	.id   = &l2tp_ip6_net_id,
816	.size = sizeof(struct l2tp_ip6_net),
817};
818
819static int __init l2tp_ip6_init(void)
820{
821	int err;
822
823	pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
824
825	err = register_pernet_device(&l2tp_ip6_net_ops);
826	if (err)
827		goto out;
828
829	err = proto_register(&l2tp_ip6_prot, 1);
830	if (err != 0)
831		goto out1;
832
833	err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
834	if (err)
835		goto out2;
836
837	inet6_register_protosw(&l2tp_ip6_protosw);
838	return 0;
839
840out2:
841	proto_unregister(&l2tp_ip6_prot);
842out1:
843	unregister_pernet_device(&l2tp_ip6_net_ops);
844out:
845	return err;
846}
847
848static void __exit l2tp_ip6_exit(void)
849{
850	inet6_unregister_protosw(&l2tp_ip6_protosw);
851	inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
852	proto_unregister(&l2tp_ip6_prot);
853	unregister_pernet_device(&l2tp_ip6_net_ops);
854}
855
856module_init(l2tp_ip6_init);
857module_exit(l2tp_ip6_exit);
858
859MODULE_LICENSE("GPL");
860MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
861MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
862MODULE_VERSION("1.0");
863
864/* Use the values of SOCK_DGRAM (2) as type and IPPROTO_L2TP (115) as protocol,
865 * because __stringify doesn't like enums
866 */
867MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 115, 2);
868MODULE_ALIAS_NET_PF_PROTO(PF_INET6, 115);