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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);
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 *uaddr, int addr_len)
284{
285 struct inet_sock *inet = inet_sk(sk);
286 struct ipv6_pinfo *np = inet6_sk(sk);
287 struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *)uaddr;
288 struct net *net = sock_net(sk);
289 struct l2tp_ip6_net *pn;
290 __be32 v4addr = 0;
291 int bound_dev_if;
292 int addr_type;
293 int err;
294
295 pn = l2tp_ip6_pernet(net);
296
297 if (addr->l2tp_family != AF_INET6)
298 return -EINVAL;
299 if (addr_len < sizeof(*addr))
300 return -EINVAL;
301
302 addr_type = ipv6_addr_type(&addr->l2tp_addr);
303
304 /* l2tp_ip6 sockets are IPv6 only */
305 if (addr_type == IPV6_ADDR_MAPPED)
306 return -EADDRNOTAVAIL;
307
308 /* L2TP is point-point, not multicast */
309 if (addr_type & IPV6_ADDR_MULTICAST)
310 return -EADDRNOTAVAIL;
311
312 lock_sock(sk);
313
314 err = -EINVAL;
315 if (!sock_flag(sk, SOCK_ZAPPED))
316 goto out_unlock;
317
318 if (sk->sk_state != TCP_CLOSE)
319 goto out_unlock;
320
321 bound_dev_if = sk->sk_bound_dev_if;
322
323 /* Check if the address belongs to the host. */
324 rcu_read_lock();
325 if (addr_type != IPV6_ADDR_ANY) {
326 struct net_device *dev = NULL;
327
328 if (addr_type & IPV6_ADDR_LINKLOCAL) {
329 if (addr->l2tp_scope_id)
330 bound_dev_if = addr->l2tp_scope_id;
331
332 /* Binding to link-local address requires an
333 * interface.
334 */
335 if (!bound_dev_if)
336 goto out_unlock_rcu;
337
338 err = -ENODEV;
339 dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
340 if (!dev)
341 goto out_unlock_rcu;
342 }
343
344 /* ipv4 addr of the socket is invalid. Only the
345 * unspecified and mapped address have a v4 equivalent.
346 */
347 v4addr = LOOPBACK4_IPV6;
348 err = -EADDRNOTAVAIL;
349 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
350 goto out_unlock_rcu;
351 }
352 rcu_read_unlock();
353
354 write_lock_bh(&pn->l2tp_ip6_lock);
355 if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
356 addr->l2tp_conn_id)) {
357 write_unlock_bh(&pn->l2tp_ip6_lock);
358 err = -EADDRINUSE;
359 goto out_unlock;
360 }
361
362 inet->inet_saddr = v4addr;
363 inet->inet_rcv_saddr = v4addr;
364 sk->sk_bound_dev_if = bound_dev_if;
365 sk->sk_v6_rcv_saddr = addr->l2tp_addr;
366 np->saddr = addr->l2tp_addr;
367
368 l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
369
370 sk_add_bind_node(sk, &pn->l2tp_ip6_bind_table);
371 sk_del_node_init(sk);
372 write_unlock_bh(&pn->l2tp_ip6_lock);
373
374 sock_reset_flag(sk, SOCK_ZAPPED);
375 release_sock(sk);
376 return 0;
377
378out_unlock_rcu:
379 rcu_read_unlock();
380out_unlock:
381 release_sock(sk);
382
383 return err;
384}
385
386static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
387 int addr_len)
388{
389 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
390 struct sockaddr_in6 *usin = (struct sockaddr_in6 *)uaddr;
391 struct in6_addr *daddr;
392 int addr_type;
393 int rc;
394 struct l2tp_ip6_net *pn;
395
396 if (addr_len < sizeof(*lsa))
397 return -EINVAL;
398
399 if (usin->sin6_family != AF_INET6)
400 return -EINVAL;
401
402 addr_type = ipv6_addr_type(&usin->sin6_addr);
403 if (addr_type & IPV6_ADDR_MULTICAST)
404 return -EINVAL;
405
406 if (addr_type & IPV6_ADDR_MAPPED) {
407 daddr = &usin->sin6_addr;
408 if (ipv4_is_multicast(daddr->s6_addr32[3]))
409 return -EINVAL;
410 }
411
412 lock_sock(sk);
413
414 /* Must bind first - autobinding does not work */
415 if (sock_flag(sk, SOCK_ZAPPED)) {
416 rc = -EINVAL;
417 goto out_sk;
418 }
419
420 rc = __ip6_datagram_connect(sk, uaddr, addr_len);
421 if (rc < 0)
422 goto out_sk;
423
424 l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
425
426 pn = l2tp_ip6_pernet(sock_net(sk));
427 write_lock_bh(&pn->l2tp_ip6_lock);
428 hlist_del_init(&sk->sk_bind_node);
429 sk_add_bind_node(sk, &pn->l2tp_ip6_bind_table);
430 write_unlock_bh(&pn->l2tp_ip6_lock);
431
432out_sk:
433 release_sock(sk);
434
435 return rc;
436}
437
438static int l2tp_ip6_disconnect(struct sock *sk, int flags)
439{
440 if (sock_flag(sk, SOCK_ZAPPED))
441 return 0;
442
443 return __udp_disconnect(sk, flags);
444}
445
446static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
447 int peer)
448{
449 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
450 struct sock *sk = sock->sk;
451 struct ipv6_pinfo *np = inet6_sk(sk);
452 struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
453
454 lsa->l2tp_family = AF_INET6;
455 lsa->l2tp_flowinfo = 0;
456 lsa->l2tp_scope_id = 0;
457 lsa->l2tp_unused = 0;
458 if (peer) {
459 if (!lsk->peer_conn_id)
460 return -ENOTCONN;
461 lsa->l2tp_conn_id = lsk->peer_conn_id;
462 lsa->l2tp_addr = sk->sk_v6_daddr;
463 if (inet6_test_bit(SNDFLOW, sk))
464 lsa->l2tp_flowinfo = np->flow_label;
465 } else {
466 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
467 lsa->l2tp_addr = np->saddr;
468 else
469 lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
470
471 lsa->l2tp_conn_id = lsk->conn_id;
472 }
473 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
474 lsa->l2tp_scope_id = READ_ONCE(sk->sk_bound_dev_if);
475 return sizeof(*lsa);
476}
477
478static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
479{
480 int rc;
481
482 /* Charge it to the socket, dropping if the queue is full. */
483 rc = sock_queue_rcv_skb(sk, skb);
484 if (rc < 0)
485 goto drop;
486
487 return 0;
488
489drop:
490 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
491 kfree_skb(skb);
492 return -1;
493}
494
495static int l2tp_ip6_push_pending_frames(struct sock *sk)
496{
497 struct sk_buff *skb;
498 __be32 *transhdr = NULL;
499 int err = 0;
500
501 skb = skb_peek(&sk->sk_write_queue);
502 if (!skb)
503 goto out;
504
505 transhdr = (__be32 *)skb_transport_header(skb);
506 *transhdr = 0;
507
508 err = ip6_push_pending_frames(sk);
509
510out:
511 return err;
512}
513
514/* Userspace will call sendmsg() on the tunnel socket to send L2TP
515 * control frames.
516 */
517static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
518{
519 struct ipv6_txoptions opt_space;
520 DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
521 struct in6_addr *daddr, *final_p, final;
522 struct ipv6_pinfo *np = inet6_sk(sk);
523 struct ipv6_txoptions *opt_to_free = NULL;
524 struct ipv6_txoptions *opt = NULL;
525 struct ip6_flowlabel *flowlabel = NULL;
526 struct dst_entry *dst = NULL;
527 struct flowi6 fl6;
528 struct ipcm6_cookie ipc6;
529 int addr_len = msg->msg_namelen;
530 int transhdrlen = 4; /* zero session-id */
531 int ulen;
532 int err;
533
534 /* Rough check on arithmetic overflow,
535 * better check is made in ip6_append_data().
536 */
537 if (len > INT_MAX - transhdrlen)
538 return -EMSGSIZE;
539
540 /* Mirror BSD error message compatibility */
541 if (msg->msg_flags & MSG_OOB)
542 return -EOPNOTSUPP;
543
544 /* Get and verify the address */
545 memset(&fl6, 0, sizeof(fl6));
546
547 fl6.flowi6_mark = READ_ONCE(sk->sk_mark);
548 fl6.flowi6_uid = sk->sk_uid;
549
550 ipcm6_init(&ipc6);
551
552 if (lsa) {
553 if (addr_len < SIN6_LEN_RFC2133)
554 return -EINVAL;
555
556 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
557 return -EAFNOSUPPORT;
558
559 daddr = &lsa->l2tp_addr;
560 if (inet6_test_bit(SNDFLOW, sk)) {
561 fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
562 if (fl6.flowlabel & IPV6_FLOWLABEL_MASK) {
563 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
564 if (IS_ERR(flowlabel))
565 return -EINVAL;
566 }
567 }
568
569 /* Otherwise it will be difficult to maintain
570 * sk->sk_dst_cache.
571 */
572 if (sk->sk_state == TCP_ESTABLISHED &&
573 ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
574 daddr = &sk->sk_v6_daddr;
575
576 if (addr_len >= sizeof(struct sockaddr_in6) &&
577 lsa->l2tp_scope_id &&
578 ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
579 fl6.flowi6_oif = lsa->l2tp_scope_id;
580 } else {
581 if (sk->sk_state != TCP_ESTABLISHED)
582 return -EDESTADDRREQ;
583
584 daddr = &sk->sk_v6_daddr;
585 fl6.flowlabel = np->flow_label;
586 }
587
588 if (fl6.flowi6_oif == 0)
589 fl6.flowi6_oif = READ_ONCE(sk->sk_bound_dev_if);
590
591 if (msg->msg_controllen) {
592 opt = &opt_space;
593 memset(opt, 0, sizeof(struct ipv6_txoptions));
594 opt->tot_len = sizeof(struct ipv6_txoptions);
595 ipc6.opt = opt;
596
597 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
598 if (err < 0) {
599 fl6_sock_release(flowlabel);
600 return err;
601 }
602 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
603 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
604 if (IS_ERR(flowlabel))
605 return -EINVAL;
606 }
607 if (!(opt->opt_nflen | opt->opt_flen))
608 opt = NULL;
609 }
610
611 if (!opt) {
612 opt = txopt_get(np);
613 opt_to_free = opt;
614 }
615 if (flowlabel)
616 opt = fl6_merge_options(&opt_space, flowlabel, opt);
617 opt = ipv6_fixup_options(&opt_space, opt);
618 ipc6.opt = opt;
619
620 fl6.flowi6_proto = sk->sk_protocol;
621 if (!ipv6_addr_any(daddr))
622 fl6.daddr = *daddr;
623 else
624 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
625 if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
626 fl6.saddr = np->saddr;
627
628 final_p = fl6_update_dst(&fl6, opt, &final);
629
630 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
631 fl6.flowi6_oif = READ_ONCE(np->mcast_oif);
632 else if (!fl6.flowi6_oif)
633 fl6.flowi6_oif = READ_ONCE(np->ucast_oif);
634
635 security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));
636
637 if (ipc6.tclass < 0)
638 ipc6.tclass = np->tclass;
639
640 fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
641
642 dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
643 if (IS_ERR(dst)) {
644 err = PTR_ERR(dst);
645 goto out;
646 }
647
648 if (ipc6.hlimit < 0)
649 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
650
651 if (ipc6.dontfrag < 0)
652 ipc6.dontfrag = inet6_test_bit(DONTFRAG, sk);
653
654 if (msg->msg_flags & MSG_CONFIRM)
655 goto do_confirm;
656
657back_from_confirm:
658 lock_sock(sk);
659 ulen = len + (skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0);
660 err = ip6_append_data(sk, ip_generic_getfrag, msg,
661 ulen, transhdrlen, &ipc6,
662 &fl6, dst_rt6_info(dst),
663 msg->msg_flags);
664 if (err)
665 ip6_flush_pending_frames(sk);
666 else if (!(msg->msg_flags & MSG_MORE))
667 err = l2tp_ip6_push_pending_frames(sk);
668 release_sock(sk);
669done:
670 dst_release(dst);
671out:
672 fl6_sock_release(flowlabel);
673 txopt_put(opt_to_free);
674
675 return err < 0 ? err : len;
676
677do_confirm:
678 if (msg->msg_flags & MSG_PROBE)
679 dst_confirm_neigh(dst, &fl6.daddr);
680 if (!(msg->msg_flags & MSG_PROBE) || len)
681 goto back_from_confirm;
682 err = 0;
683 goto done;
684}
685
686static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
687 int flags, int *addr_len)
688{
689 struct ipv6_pinfo *np = inet6_sk(sk);
690 DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
691 size_t copied = 0;
692 int err = -EOPNOTSUPP;
693 struct sk_buff *skb;
694
695 if (flags & MSG_OOB)
696 goto out;
697
698 if (flags & MSG_ERRQUEUE)
699 return ipv6_recv_error(sk, msg, len, addr_len);
700
701 skb = skb_recv_datagram(sk, flags, &err);
702 if (!skb)
703 goto out;
704
705 copied = skb->len;
706 if (len < copied) {
707 msg->msg_flags |= MSG_TRUNC;
708 copied = len;
709 }
710
711 err = skb_copy_datagram_msg(skb, 0, msg, copied);
712 if (err)
713 goto done;
714
715 sock_recv_timestamp(msg, sk, skb);
716
717 /* Copy the address. */
718 if (lsa) {
719 lsa->l2tp_family = AF_INET6;
720 lsa->l2tp_unused = 0;
721 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
722 lsa->l2tp_flowinfo = 0;
723 lsa->l2tp_scope_id = 0;
724 lsa->l2tp_conn_id = 0;
725 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
726 lsa->l2tp_scope_id = inet6_iif(skb);
727 *addr_len = sizeof(*lsa);
728 }
729
730 if (np->rxopt.all)
731 ip6_datagram_recv_ctl(sk, msg, skb);
732
733 if (flags & MSG_TRUNC)
734 copied = skb->len;
735done:
736 skb_free_datagram(sk, skb);
737out:
738 return err ? err : copied;
739}
740
741static struct proto l2tp_ip6_prot = {
742 .name = "L2TP/IPv6",
743 .owner = THIS_MODULE,
744 .init = l2tp_ip6_open,
745 .close = l2tp_ip6_close,
746 .bind = l2tp_ip6_bind,
747 .connect = l2tp_ip6_connect,
748 .disconnect = l2tp_ip6_disconnect,
749 .ioctl = l2tp_ioctl,
750 .destroy = l2tp_ip6_destroy_sock,
751 .setsockopt = ipv6_setsockopt,
752 .getsockopt = ipv6_getsockopt,
753 .sendmsg = l2tp_ip6_sendmsg,
754 .recvmsg = l2tp_ip6_recvmsg,
755 .backlog_rcv = l2tp_ip6_backlog_recv,
756 .hash = l2tp_ip6_hash,
757 .unhash = l2tp_ip6_unhash,
758 .obj_size = sizeof(struct l2tp_ip6_sock),
759 .ipv6_pinfo_offset = offsetof(struct l2tp_ip6_sock, inet6),
760};
761
762static const struct proto_ops l2tp_ip6_ops = {
763 .family = PF_INET6,
764 .owner = THIS_MODULE,
765 .release = inet6_release,
766 .bind = inet6_bind,
767 .connect = inet_dgram_connect,
768 .socketpair = sock_no_socketpair,
769 .accept = sock_no_accept,
770 .getname = l2tp_ip6_getname,
771 .poll = datagram_poll,
772 .ioctl = inet6_ioctl,
773 .gettstamp = sock_gettstamp,
774 .listen = sock_no_listen,
775 .shutdown = inet_shutdown,
776 .setsockopt = sock_common_setsockopt,
777 .getsockopt = sock_common_getsockopt,
778 .sendmsg = inet_sendmsg,
779 .recvmsg = sock_common_recvmsg,
780 .mmap = sock_no_mmap,
781#ifdef CONFIG_COMPAT
782 .compat_ioctl = inet6_compat_ioctl,
783#endif
784};
785
786static struct inet_protosw l2tp_ip6_protosw = {
787 .type = SOCK_DGRAM,
788 .protocol = IPPROTO_L2TP,
789 .prot = &l2tp_ip6_prot,
790 .ops = &l2tp_ip6_ops,
791};
792
793static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
794 .handler = l2tp_ip6_recv,
795};
796
797static __net_init int l2tp_ip6_init_net(struct net *net)
798{
799 struct l2tp_ip6_net *pn = net_generic(net, l2tp_ip6_net_id);
800
801 rwlock_init(&pn->l2tp_ip6_lock);
802 INIT_HLIST_HEAD(&pn->l2tp_ip6_table);
803 INIT_HLIST_HEAD(&pn->l2tp_ip6_bind_table);
804 return 0;
805}
806
807static __net_exit void l2tp_ip6_exit_net(struct net *net)
808{
809 struct l2tp_ip6_net *pn = l2tp_ip6_pernet(net);
810
811 write_lock_bh(&pn->l2tp_ip6_lock);
812 WARN_ON_ONCE(hlist_count_nodes(&pn->l2tp_ip6_table) != 0);
813 WARN_ON_ONCE(hlist_count_nodes(&pn->l2tp_ip6_bind_table) != 0);
814 write_unlock_bh(&pn->l2tp_ip6_lock);
815}
816
817static struct pernet_operations l2tp_ip6_net_ops = {
818 .init = l2tp_ip6_init_net,
819 .exit = l2tp_ip6_exit_net,
820 .id = &l2tp_ip6_net_id,
821 .size = sizeof(struct l2tp_ip6_net),
822};
823
824static int __init l2tp_ip6_init(void)
825{
826 int err;
827
828 pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
829
830 err = register_pernet_device(&l2tp_ip6_net_ops);
831 if (err)
832 goto out;
833
834 err = proto_register(&l2tp_ip6_prot, 1);
835 if (err != 0)
836 goto out1;
837
838 err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
839 if (err)
840 goto out2;
841
842 inet6_register_protosw(&l2tp_ip6_protosw);
843 return 0;
844
845out2:
846 proto_unregister(&l2tp_ip6_prot);
847out1:
848 unregister_pernet_device(&l2tp_ip6_net_ops);
849out:
850 return err;
851}
852
853static void __exit l2tp_ip6_exit(void)
854{
855 inet6_unregister_protosw(&l2tp_ip6_protosw);
856 inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
857 proto_unregister(&l2tp_ip6_prot);
858 unregister_pernet_device(&l2tp_ip6_net_ops);
859}
860
861module_init(l2tp_ip6_init);
862module_exit(l2tp_ip6_exit);
863
864MODULE_LICENSE("GPL");
865MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
866MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
867MODULE_VERSION("1.0");
868
869/* Use the values of SOCK_DGRAM (2) as type and IPPROTO_L2TP (115) as protocol,
870 * because __stringify doesn't like enums
871 */
872MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 115, 2);
873MODULE_ALIAS_NET_PF_PROTO(PF_INET6, 115);