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1/*
2 * L2TPv3 IP encapsulation support for IPv6
3 *
4 * Copyright (c) 2012 Katalix Systems Ltd
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <linux/icmp.h>
15#include <linux/module.h>
16#include <linux/skbuff.h>
17#include <linux/random.h>
18#include <linux/socket.h>
19#include <linux/l2tp.h>
20#include <linux/in.h>
21#include <linux/in6.h>
22#include <net/sock.h>
23#include <net/ip.h>
24#include <net/icmp.h>
25#include <net/udp.h>
26#include <net/inet_common.h>
27#include <net/inet_hashtables.h>
28#include <net/inet6_hashtables.h>
29#include <net/tcp_states.h>
30#include <net/protocol.h>
31#include <net/xfrm.h>
32
33#include <net/transp_v6.h>
34#include <net/addrconf.h>
35#include <net/ip6_route.h>
36
37#include "l2tp_core.h"
38
39struct l2tp_ip6_sock {
40 /* inet_sock has to be the first member of l2tp_ip6_sock */
41 struct inet_sock inet;
42
43 u32 conn_id;
44 u32 peer_conn_id;
45
46 /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
47 inet6_sk_generic */
48 struct ipv6_pinfo inet6;
49};
50
51static DEFINE_RWLOCK(l2tp_ip6_lock);
52static struct hlist_head l2tp_ip6_table;
53static struct hlist_head l2tp_ip6_bind_table;
54
55static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
56{
57 return (struct l2tp_ip6_sock *)sk;
58}
59
60static struct sock *__l2tp_ip6_bind_lookup(struct net *net,
61 struct in6_addr *laddr,
62 const struct in6_addr *raddr,
63 int dif, u32 tunnel_id)
64{
65 struct sock *sk;
66
67 sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
68 const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
69 const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
70 struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
71
72 if (l2tp == NULL)
73 continue;
74
75 if ((l2tp->conn_id == tunnel_id) &&
76 net_eq(sock_net(sk), net) &&
77 (!sk_laddr || ipv6_addr_any(sk_laddr) || ipv6_addr_equal(sk_laddr, laddr)) &&
78 (!raddr || ipv6_addr_any(sk_raddr) || ipv6_addr_equal(sk_raddr, raddr)) &&
79 (!sk->sk_bound_dev_if || !dif ||
80 sk->sk_bound_dev_if == dif))
81 goto found;
82 }
83
84 sk = NULL;
85found:
86 return sk;
87}
88
89/* When processing receive frames, there are two cases to
90 * consider. Data frames consist of a non-zero session-id and an
91 * optional cookie. Control frames consist of a regular L2TP header
92 * preceded by 32-bits of zeros.
93 *
94 * L2TPv3 Session Header Over IP
95 *
96 * 0 1 2 3
97 * 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
98 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
99 * | Session ID |
100 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
101 * | Cookie (optional, maximum 64 bits)...
102 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
103 * |
104 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
105 *
106 * L2TPv3 Control Message Header Over IP
107 *
108 * 0 1 2 3
109 * 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
110 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
111 * | (32 bits of zeros) |
112 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
113 * |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length |
114 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
115 * | Control Connection ID |
116 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
117 * | Ns | Nr |
118 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
119 *
120 * All control frames are passed to userspace.
121 */
122static int l2tp_ip6_recv(struct sk_buff *skb)
123{
124 struct net *net = dev_net(skb->dev);
125 struct sock *sk;
126 u32 session_id;
127 u32 tunnel_id;
128 unsigned char *ptr, *optr;
129 struct l2tp_session *session;
130 struct l2tp_tunnel *tunnel = NULL;
131 int length;
132
133 if (!pskb_may_pull(skb, 4))
134 goto discard;
135
136 /* Point to L2TP header */
137 optr = ptr = skb->data;
138 session_id = ntohl(*((__be32 *) ptr));
139 ptr += 4;
140
141 /* RFC3931: L2TP/IP packets have the first 4 bytes containing
142 * the session_id. If it is 0, the packet is a L2TP control
143 * frame and the session_id value can be discarded.
144 */
145 if (session_id == 0) {
146 __skb_pull(skb, 4);
147 goto pass_up;
148 }
149
150 /* Ok, this is a data packet. Lookup the session. */
151 session = l2tp_session_find(net, NULL, session_id);
152 if (session == NULL)
153 goto discard;
154
155 tunnel = session->tunnel;
156 if (tunnel == NULL)
157 goto discard;
158
159 /* Trace packet contents, if enabled */
160 if (tunnel->debug & L2TP_MSG_DATA) {
161 length = min(32u, skb->len);
162 if (!pskb_may_pull(skb, length))
163 goto discard;
164
165 /* Point to L2TP header */
166 optr = ptr = skb->data;
167 ptr += 4;
168 pr_debug("%s: ip recv\n", tunnel->name);
169 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
170 }
171
172 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
173 tunnel->recv_payload_hook);
174 return 0;
175
176pass_up:
177 /* Get the tunnel_id from the L2TP header */
178 if (!pskb_may_pull(skb, 12))
179 goto discard;
180
181 if ((skb->data[0] & 0xc0) != 0xc0)
182 goto discard;
183
184 tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
185 tunnel = l2tp_tunnel_find(net, tunnel_id);
186 if (tunnel != NULL)
187 sk = tunnel->sock;
188 else {
189 struct ipv6hdr *iph = ipv6_hdr(skb);
190
191 read_lock_bh(&l2tp_ip6_lock);
192 sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
193 inet6_iif(skb), tunnel_id);
194 if (!sk) {
195 read_unlock_bh(&l2tp_ip6_lock);
196 goto discard;
197 }
198
199 sock_hold(sk);
200 read_unlock_bh(&l2tp_ip6_lock);
201 }
202
203 if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
204 goto discard_put;
205
206 nf_reset(skb);
207
208 return sk_receive_skb(sk, skb, 1);
209
210discard_put:
211 sock_put(sk);
212
213discard:
214 kfree_skb(skb);
215 return 0;
216}
217
218static int l2tp_ip6_open(struct sock *sk)
219{
220 /* Prevent autobind. We don't have ports. */
221 inet_sk(sk)->inet_num = IPPROTO_L2TP;
222
223 write_lock_bh(&l2tp_ip6_lock);
224 sk_add_node(sk, &l2tp_ip6_table);
225 write_unlock_bh(&l2tp_ip6_lock);
226
227 return 0;
228}
229
230static void l2tp_ip6_close(struct sock *sk, long timeout)
231{
232 write_lock_bh(&l2tp_ip6_lock);
233 hlist_del_init(&sk->sk_bind_node);
234 sk_del_node_init(sk);
235 write_unlock_bh(&l2tp_ip6_lock);
236
237 sk_common_release(sk);
238}
239
240static void l2tp_ip6_destroy_sock(struct sock *sk)
241{
242 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
243
244 lock_sock(sk);
245 ip6_flush_pending_frames(sk);
246 release_sock(sk);
247
248 if (tunnel) {
249 l2tp_tunnel_closeall(tunnel);
250 sock_put(sk);
251 }
252
253 inet6_destroy_sock(sk);
254}
255
256static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
257{
258 struct inet_sock *inet = inet_sk(sk);
259 struct ipv6_pinfo *np = inet6_sk(sk);
260 struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
261 struct net *net = sock_net(sk);
262 __be32 v4addr = 0;
263 int bound_dev_if;
264 int addr_type;
265 int err;
266
267 if (addr->l2tp_family != AF_INET6)
268 return -EINVAL;
269 if (addr_len < sizeof(*addr))
270 return -EINVAL;
271
272 addr_type = ipv6_addr_type(&addr->l2tp_addr);
273
274 /* l2tp_ip6 sockets are IPv6 only */
275 if (addr_type == IPV6_ADDR_MAPPED)
276 return -EADDRNOTAVAIL;
277
278 /* L2TP is point-point, not multicast */
279 if (addr_type & IPV6_ADDR_MULTICAST)
280 return -EADDRNOTAVAIL;
281
282 lock_sock(sk);
283
284 err = -EINVAL;
285 if (!sock_flag(sk, SOCK_ZAPPED))
286 goto out_unlock;
287
288 if (sk->sk_state != TCP_CLOSE)
289 goto out_unlock;
290
291 bound_dev_if = sk->sk_bound_dev_if;
292
293 /* Check if the address belongs to the host. */
294 rcu_read_lock();
295 if (addr_type != IPV6_ADDR_ANY) {
296 struct net_device *dev = NULL;
297
298 if (addr_type & IPV6_ADDR_LINKLOCAL) {
299 if (addr->l2tp_scope_id)
300 bound_dev_if = addr->l2tp_scope_id;
301
302 /* Binding to link-local address requires an
303 * interface.
304 */
305 if (!bound_dev_if)
306 goto out_unlock_rcu;
307
308 err = -ENODEV;
309 dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
310 if (!dev)
311 goto out_unlock_rcu;
312 }
313
314 /* ipv4 addr of the socket is invalid. Only the
315 * unspecified and mapped address have a v4 equivalent.
316 */
317 v4addr = LOOPBACK4_IPV6;
318 err = -EADDRNOTAVAIL;
319 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
320 goto out_unlock_rcu;
321 }
322 rcu_read_unlock();
323
324 write_lock_bh(&l2tp_ip6_lock);
325 if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
326 addr->l2tp_conn_id)) {
327 write_unlock_bh(&l2tp_ip6_lock);
328 err = -EADDRINUSE;
329 goto out_unlock;
330 }
331
332 inet->inet_saddr = v4addr;
333 inet->inet_rcv_saddr = v4addr;
334 sk->sk_bound_dev_if = bound_dev_if;
335 sk->sk_v6_rcv_saddr = addr->l2tp_addr;
336 np->saddr = addr->l2tp_addr;
337
338 l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
339
340 sk_add_bind_node(sk, &l2tp_ip6_bind_table);
341 sk_del_node_init(sk);
342 write_unlock_bh(&l2tp_ip6_lock);
343
344 sock_reset_flag(sk, SOCK_ZAPPED);
345 release_sock(sk);
346 return 0;
347
348out_unlock_rcu:
349 rcu_read_unlock();
350out_unlock:
351 release_sock(sk);
352
353 return err;
354}
355
356static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
357 int addr_len)
358{
359 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
360 struct sockaddr_in6 *usin = (struct sockaddr_in6 *) uaddr;
361 struct in6_addr *daddr;
362 int addr_type;
363 int rc;
364
365 if (addr_len < sizeof(*lsa))
366 return -EINVAL;
367
368 if (usin->sin6_family != AF_INET6)
369 return -EINVAL;
370
371 addr_type = ipv6_addr_type(&usin->sin6_addr);
372 if (addr_type & IPV6_ADDR_MULTICAST)
373 return -EINVAL;
374
375 if (addr_type & IPV6_ADDR_MAPPED) {
376 daddr = &usin->sin6_addr;
377 if (ipv4_is_multicast(daddr->s6_addr32[3]))
378 return -EINVAL;
379 }
380
381 lock_sock(sk);
382
383 /* Must bind first - autobinding does not work */
384 if (sock_flag(sk, SOCK_ZAPPED)) {
385 rc = -EINVAL;
386 goto out_sk;
387 }
388
389 rc = __ip6_datagram_connect(sk, uaddr, addr_len);
390 if (rc < 0)
391 goto out_sk;
392
393 l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
394
395 write_lock_bh(&l2tp_ip6_lock);
396 hlist_del_init(&sk->sk_bind_node);
397 sk_add_bind_node(sk, &l2tp_ip6_bind_table);
398 write_unlock_bh(&l2tp_ip6_lock);
399
400out_sk:
401 release_sock(sk);
402
403 return rc;
404}
405
406static int l2tp_ip6_disconnect(struct sock *sk, int flags)
407{
408 if (sock_flag(sk, SOCK_ZAPPED))
409 return 0;
410
411 return __udp_disconnect(sk, flags);
412}
413
414static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
415 int *uaddr_len, int peer)
416{
417 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
418 struct sock *sk = sock->sk;
419 struct ipv6_pinfo *np = inet6_sk(sk);
420 struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
421
422 lsa->l2tp_family = AF_INET6;
423 lsa->l2tp_flowinfo = 0;
424 lsa->l2tp_scope_id = 0;
425 lsa->l2tp_unused = 0;
426 if (peer) {
427 if (!lsk->peer_conn_id)
428 return -ENOTCONN;
429 lsa->l2tp_conn_id = lsk->peer_conn_id;
430 lsa->l2tp_addr = sk->sk_v6_daddr;
431 if (np->sndflow)
432 lsa->l2tp_flowinfo = np->flow_label;
433 } else {
434 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
435 lsa->l2tp_addr = np->saddr;
436 else
437 lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
438
439 lsa->l2tp_conn_id = lsk->conn_id;
440 }
441 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
442 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
443 *uaddr_len = sizeof(*lsa);
444 return 0;
445}
446
447static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
448{
449 int rc;
450
451 /* Charge it to the socket, dropping if the queue is full. */
452 rc = sock_queue_rcv_skb(sk, skb);
453 if (rc < 0)
454 goto drop;
455
456 return 0;
457
458drop:
459 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
460 kfree_skb(skb);
461 return -1;
462}
463
464static int l2tp_ip6_push_pending_frames(struct sock *sk)
465{
466 struct sk_buff *skb;
467 __be32 *transhdr = NULL;
468 int err = 0;
469
470 skb = skb_peek(&sk->sk_write_queue);
471 if (skb == NULL)
472 goto out;
473
474 transhdr = (__be32 *)skb_transport_header(skb);
475 *transhdr = 0;
476
477 err = ip6_push_pending_frames(sk);
478
479out:
480 return err;
481}
482
483/* Userspace will call sendmsg() on the tunnel socket to send L2TP
484 * control frames.
485 */
486static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
487{
488 struct ipv6_txoptions opt_space;
489 DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
490 struct in6_addr *daddr, *final_p, final;
491 struct ipv6_pinfo *np = inet6_sk(sk);
492 struct ipv6_txoptions *opt_to_free = NULL;
493 struct ipv6_txoptions *opt = NULL;
494 struct ip6_flowlabel *flowlabel = NULL;
495 struct dst_entry *dst = NULL;
496 struct flowi6 fl6;
497 struct sockcm_cookie sockc_unused = {0};
498 struct ipcm6_cookie ipc6;
499 int addr_len = msg->msg_namelen;
500 int transhdrlen = 4; /* zero session-id */
501 int ulen = len + transhdrlen;
502 int err;
503
504 /* Rough check on arithmetic overflow,
505 better check is made in ip6_append_data().
506 */
507 if (len > INT_MAX)
508 return -EMSGSIZE;
509
510 /* Mirror BSD error message compatibility */
511 if (msg->msg_flags & MSG_OOB)
512 return -EOPNOTSUPP;
513
514 /*
515 * Get and verify the address.
516 */
517 memset(&fl6, 0, sizeof(fl6));
518
519 fl6.flowi6_mark = sk->sk_mark;
520 fl6.flowi6_uid = sk->sk_uid;
521
522 ipc6.hlimit = -1;
523 ipc6.tclass = -1;
524 ipc6.dontfrag = -1;
525
526 if (lsa) {
527 if (addr_len < SIN6_LEN_RFC2133)
528 return -EINVAL;
529
530 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
531 return -EAFNOSUPPORT;
532
533 daddr = &lsa->l2tp_addr;
534 if (np->sndflow) {
535 fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
536 if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
537 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
538 if (flowlabel == NULL)
539 return -EINVAL;
540 }
541 }
542
543 /*
544 * Otherwise it will be difficult to maintain
545 * sk->sk_dst_cache.
546 */
547 if (sk->sk_state == TCP_ESTABLISHED &&
548 ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
549 daddr = &sk->sk_v6_daddr;
550
551 if (addr_len >= sizeof(struct sockaddr_in6) &&
552 lsa->l2tp_scope_id &&
553 ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
554 fl6.flowi6_oif = lsa->l2tp_scope_id;
555 } else {
556 if (sk->sk_state != TCP_ESTABLISHED)
557 return -EDESTADDRREQ;
558
559 daddr = &sk->sk_v6_daddr;
560 fl6.flowlabel = np->flow_label;
561 }
562
563 if (fl6.flowi6_oif == 0)
564 fl6.flowi6_oif = sk->sk_bound_dev_if;
565
566 if (msg->msg_controllen) {
567 opt = &opt_space;
568 memset(opt, 0, sizeof(struct ipv6_txoptions));
569 opt->tot_len = sizeof(struct ipv6_txoptions);
570 ipc6.opt = opt;
571
572 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6,
573 &sockc_unused);
574 if (err < 0) {
575 fl6_sock_release(flowlabel);
576 return err;
577 }
578 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
579 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
580 if (flowlabel == NULL)
581 return -EINVAL;
582 }
583 if (!(opt->opt_nflen|opt->opt_flen))
584 opt = NULL;
585 }
586
587 if (!opt) {
588 opt = txopt_get(np);
589 opt_to_free = opt;
590 }
591 if (flowlabel)
592 opt = fl6_merge_options(&opt_space, flowlabel, opt);
593 opt = ipv6_fixup_options(&opt_space, opt);
594 ipc6.opt = opt;
595
596 fl6.flowi6_proto = sk->sk_protocol;
597 if (!ipv6_addr_any(daddr))
598 fl6.daddr = *daddr;
599 else
600 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
601 if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
602 fl6.saddr = np->saddr;
603
604 final_p = fl6_update_dst(&fl6, opt, &final);
605
606 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
607 fl6.flowi6_oif = np->mcast_oif;
608 else if (!fl6.flowi6_oif)
609 fl6.flowi6_oif = np->ucast_oif;
610
611 security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
612
613 if (ipc6.tclass < 0)
614 ipc6.tclass = np->tclass;
615
616 fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
617
618 dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
619 if (IS_ERR(dst)) {
620 err = PTR_ERR(dst);
621 goto out;
622 }
623
624 if (ipc6.hlimit < 0)
625 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
626
627 if (ipc6.dontfrag < 0)
628 ipc6.dontfrag = np->dontfrag;
629
630 if (msg->msg_flags & MSG_CONFIRM)
631 goto do_confirm;
632
633back_from_confirm:
634 lock_sock(sk);
635 err = ip6_append_data(sk, ip_generic_getfrag, msg,
636 ulen, transhdrlen, &ipc6,
637 &fl6, (struct rt6_info *)dst,
638 msg->msg_flags, &sockc_unused);
639 if (err)
640 ip6_flush_pending_frames(sk);
641 else if (!(msg->msg_flags & MSG_MORE))
642 err = l2tp_ip6_push_pending_frames(sk);
643 release_sock(sk);
644done:
645 dst_release(dst);
646out:
647 fl6_sock_release(flowlabel);
648 txopt_put(opt_to_free);
649
650 return err < 0 ? err : len;
651
652do_confirm:
653 dst_confirm(dst);
654 if (!(msg->msg_flags & MSG_PROBE) || len)
655 goto back_from_confirm;
656 err = 0;
657 goto done;
658}
659
660static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
661 int noblock, int flags, int *addr_len)
662{
663 struct ipv6_pinfo *np = inet6_sk(sk);
664 DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
665 size_t copied = 0;
666 int err = -EOPNOTSUPP;
667 struct sk_buff *skb;
668
669 if (flags & MSG_OOB)
670 goto out;
671
672 if (addr_len)
673 *addr_len = sizeof(*lsa);
674
675 if (flags & MSG_ERRQUEUE)
676 return ipv6_recv_error(sk, msg, len, addr_len);
677
678 skb = skb_recv_datagram(sk, flags, noblock, &err);
679 if (!skb)
680 goto out;
681
682 copied = skb->len;
683 if (len < copied) {
684 msg->msg_flags |= MSG_TRUNC;
685 copied = len;
686 }
687
688 err = skb_copy_datagram_msg(skb, 0, msg, copied);
689 if (err)
690 goto done;
691
692 sock_recv_timestamp(msg, sk, skb);
693
694 /* Copy the address. */
695 if (lsa) {
696 lsa->l2tp_family = AF_INET6;
697 lsa->l2tp_unused = 0;
698 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
699 lsa->l2tp_flowinfo = 0;
700 lsa->l2tp_scope_id = 0;
701 lsa->l2tp_conn_id = 0;
702 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
703 lsa->l2tp_scope_id = inet6_iif(skb);
704 }
705
706 if (np->rxopt.all)
707 ip6_datagram_recv_ctl(sk, msg, skb);
708
709 if (flags & MSG_TRUNC)
710 copied = skb->len;
711done:
712 skb_free_datagram(sk, skb);
713out:
714 return err ? err : copied;
715}
716
717static struct proto l2tp_ip6_prot = {
718 .name = "L2TP/IPv6",
719 .owner = THIS_MODULE,
720 .init = l2tp_ip6_open,
721 .close = l2tp_ip6_close,
722 .bind = l2tp_ip6_bind,
723 .connect = l2tp_ip6_connect,
724 .disconnect = l2tp_ip6_disconnect,
725 .ioctl = l2tp_ioctl,
726 .destroy = l2tp_ip6_destroy_sock,
727 .setsockopt = ipv6_setsockopt,
728 .getsockopt = ipv6_getsockopt,
729 .sendmsg = l2tp_ip6_sendmsg,
730 .recvmsg = l2tp_ip6_recvmsg,
731 .backlog_rcv = l2tp_ip6_backlog_recv,
732 .hash = inet6_hash,
733 .unhash = inet_unhash,
734 .obj_size = sizeof(struct l2tp_ip6_sock),
735#ifdef CONFIG_COMPAT
736 .compat_setsockopt = compat_ipv6_setsockopt,
737 .compat_getsockopt = compat_ipv6_getsockopt,
738#endif
739};
740
741static const struct proto_ops l2tp_ip6_ops = {
742 .family = PF_INET6,
743 .owner = THIS_MODULE,
744 .release = inet6_release,
745 .bind = inet6_bind,
746 .connect = inet_dgram_connect,
747 .socketpair = sock_no_socketpair,
748 .accept = sock_no_accept,
749 .getname = l2tp_ip6_getname,
750 .poll = datagram_poll,
751 .ioctl = inet6_ioctl,
752 .listen = sock_no_listen,
753 .shutdown = inet_shutdown,
754 .setsockopt = sock_common_setsockopt,
755 .getsockopt = sock_common_getsockopt,
756 .sendmsg = inet_sendmsg,
757 .recvmsg = sock_common_recvmsg,
758 .mmap = sock_no_mmap,
759 .sendpage = sock_no_sendpage,
760#ifdef CONFIG_COMPAT
761 .compat_setsockopt = compat_sock_common_setsockopt,
762 .compat_getsockopt = compat_sock_common_getsockopt,
763#endif
764};
765
766static struct inet_protosw l2tp_ip6_protosw = {
767 .type = SOCK_DGRAM,
768 .protocol = IPPROTO_L2TP,
769 .prot = &l2tp_ip6_prot,
770 .ops = &l2tp_ip6_ops,
771};
772
773static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
774 .handler = l2tp_ip6_recv,
775};
776
777static int __init l2tp_ip6_init(void)
778{
779 int err;
780
781 pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
782
783 err = proto_register(&l2tp_ip6_prot, 1);
784 if (err != 0)
785 goto out;
786
787 err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
788 if (err)
789 goto out1;
790
791 inet6_register_protosw(&l2tp_ip6_protosw);
792 return 0;
793
794out1:
795 proto_unregister(&l2tp_ip6_prot);
796out:
797 return err;
798}
799
800static void __exit l2tp_ip6_exit(void)
801{
802 inet6_unregister_protosw(&l2tp_ip6_protosw);
803 inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
804 proto_unregister(&l2tp_ip6_prot);
805}
806
807module_init(l2tp_ip6_init);
808module_exit(l2tp_ip6_exit);
809
810MODULE_LICENSE("GPL");
811MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
812MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
813MODULE_VERSION("1.0");
814
815/* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
816 * enums
817 */
818MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
819MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);
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);