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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#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);
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* L2TPv3 IP encapsulation support for IPv6
3 *
4 * Copyright (c) 2012 Katalix Systems Ltd
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/icmp.h>
10#include <linux/module.h>
11#include <linux/skbuff.h>
12#include <linux/random.h>
13#include <linux/socket.h>
14#include <linux/l2tp.h>
15#include <linux/in.h>
16#include <linux/in6.h>
17#include <net/sock.h>
18#include <net/ip.h>
19#include <net/icmp.h>
20#include <net/udp.h>
21#include <net/inet_common.h>
22#include <net/tcp_states.h>
23#include <net/protocol.h>
24#include <net/xfrm.h>
25
26#include <net/transp_v6.h>
27#include <net/addrconf.h>
28#include <net/ip6_route.h>
29
30#include "l2tp_core.h"
31
32struct l2tp_ip6_sock {
33 /* inet_sock has to be the first member of l2tp_ip6_sock */
34 struct inet_sock inet;
35
36 u32 conn_id;
37 u32 peer_conn_id;
38
39 /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
40 * inet6_sk_generic
41 */
42 struct ipv6_pinfo inet6;
43};
44
45static DEFINE_RWLOCK(l2tp_ip6_lock);
46static struct hlist_head l2tp_ip6_table;
47static struct hlist_head l2tp_ip6_bind_table;
48
49static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
50{
51 return (struct l2tp_ip6_sock *)sk;
52}
53
54static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
55 const struct in6_addr *laddr,
56 const struct in6_addr *raddr,
57 int dif, u32 tunnel_id)
58{
59 struct sock *sk;
60
61 sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
62 const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
63 const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
64 const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
65
66 if (!net_eq(sock_net(sk), net))
67 continue;
68
69 if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
70 continue;
71
72 if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
73 !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
74 continue;
75
76 if (!ipv6_addr_any(sk_raddr) && raddr &&
77 !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
78 continue;
79
80 if (l2tp->conn_id != tunnel_id)
81 continue;
82
83 goto found;
84 }
85
86 sk = NULL;
87found:
88 return sk;
89}
90
91/* When processing receive frames, there are two cases to
92 * consider. Data frames consist of a non-zero session-id and an
93 * optional cookie. Control frames consist of a regular L2TP header
94 * preceded by 32-bits of zeros.
95 *
96 * L2TPv3 Session Header Over IP
97 *
98 * 0 1 2 3
99 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
100 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
101 * | Session ID |
102 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
103 * | Cookie (optional, maximum 64 bits)...
104 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
105 * |
106 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
107 *
108 * L2TPv3 Control Message Header Over IP
109 *
110 * 0 1 2 3
111 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
112 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
113 * | (32 bits of zeros) |
114 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
115 * |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length |
116 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
117 * | Control Connection ID |
118 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
119 * | Ns | Nr |
120 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
121 *
122 * All control frames are passed to userspace.
123 */
124static int l2tp_ip6_recv(struct sk_buff *skb)
125{
126 struct net *net = dev_net(skb->dev);
127 struct sock *sk;
128 u32 session_id;
129 u32 tunnel_id;
130 unsigned char *ptr, *optr;
131 struct l2tp_session *session;
132 struct l2tp_tunnel *tunnel = NULL;
133 struct ipv6hdr *iph;
134
135 if (!pskb_may_pull(skb, 4))
136 goto discard;
137
138 /* Point to L2TP header */
139 optr = skb->data;
140 ptr = skb->data;
141 session_id = ntohl(*((__be32 *)ptr));
142 ptr += 4;
143
144 /* RFC3931: L2TP/IP packets have the first 4 bytes containing
145 * the session_id. If it is 0, the packet is a L2TP control
146 * frame and the session_id value can be discarded.
147 */
148 if (session_id == 0) {
149 __skb_pull(skb, 4);
150 goto pass_up;
151 }
152
153 /* Ok, this is a data packet. Lookup the session. */
154 session = l2tp_session_get(net, session_id);
155 if (!session)
156 goto discard;
157
158 tunnel = session->tunnel;
159 if (!tunnel)
160 goto discard_sess;
161
162 if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
163 goto discard_sess;
164
165 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
166 l2tp_session_dec_refcount(session);
167
168 return 0;
169
170pass_up:
171 /* Get the tunnel_id from the L2TP header */
172 if (!pskb_may_pull(skb, 12))
173 goto discard;
174
175 if ((skb->data[0] & 0xc0) != 0xc0)
176 goto discard;
177
178 tunnel_id = ntohl(*(__be32 *)&skb->data[4]);
179 iph = ipv6_hdr(skb);
180
181 read_lock_bh(&l2tp_ip6_lock);
182 sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
183 inet6_iif(skb), tunnel_id);
184 if (!sk) {
185 read_unlock_bh(&l2tp_ip6_lock);
186 goto discard;
187 }
188 sock_hold(sk);
189 read_unlock_bh(&l2tp_ip6_lock);
190
191 if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
192 goto discard_put;
193
194 nf_reset_ct(skb);
195
196 return sk_receive_skb(sk, skb, 1);
197
198discard_sess:
199 l2tp_session_dec_refcount(session);
200 goto discard;
201
202discard_put:
203 sock_put(sk);
204
205discard:
206 kfree_skb(skb);
207 return 0;
208}
209
210static int l2tp_ip6_hash(struct sock *sk)
211{
212 if (sk_unhashed(sk)) {
213 write_lock_bh(&l2tp_ip6_lock);
214 sk_add_node(sk, &l2tp_ip6_table);
215 write_unlock_bh(&l2tp_ip6_lock);
216 }
217 return 0;
218}
219
220static void l2tp_ip6_unhash(struct sock *sk)
221{
222 if (sk_unhashed(sk))
223 return;
224 write_lock_bh(&l2tp_ip6_lock);
225 sk_del_node_init(sk);
226 write_unlock_bh(&l2tp_ip6_lock);
227}
228
229static int l2tp_ip6_open(struct sock *sk)
230{
231 /* Prevent autobind. We don't have ports. */
232 inet_sk(sk)->inet_num = IPPROTO_L2TP;
233
234 l2tp_ip6_hash(sk);
235 return 0;
236}
237
238static void l2tp_ip6_close(struct sock *sk, long timeout)
239{
240 write_lock_bh(&l2tp_ip6_lock);
241 hlist_del_init(&sk->sk_bind_node);
242 sk_del_node_init(sk);
243 write_unlock_bh(&l2tp_ip6_lock);
244
245 sk_common_release(sk);
246}
247
248static void l2tp_ip6_destroy_sock(struct sock *sk)
249{
250 struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
251
252 lock_sock(sk);
253 ip6_flush_pending_frames(sk);
254 release_sock(sk);
255
256 if (tunnel)
257 l2tp_tunnel_delete(tunnel);
258
259 inet6_destroy_sock(sk);
260}
261
262static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
263{
264 struct inet_sock *inet = inet_sk(sk);
265 struct ipv6_pinfo *np = inet6_sk(sk);
266 struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *)uaddr;
267 struct net *net = sock_net(sk);
268 __be32 v4addr = 0;
269 int bound_dev_if;
270 int addr_type;
271 int err;
272
273 if (addr->l2tp_family != AF_INET6)
274 return -EINVAL;
275 if (addr_len < sizeof(*addr))
276 return -EINVAL;
277
278 addr_type = ipv6_addr_type(&addr->l2tp_addr);
279
280 /* l2tp_ip6 sockets are IPv6 only */
281 if (addr_type == IPV6_ADDR_MAPPED)
282 return -EADDRNOTAVAIL;
283
284 /* L2TP is point-point, not multicast */
285 if (addr_type & IPV6_ADDR_MULTICAST)
286 return -EADDRNOTAVAIL;
287
288 lock_sock(sk);
289
290 err = -EINVAL;
291 if (!sock_flag(sk, SOCK_ZAPPED))
292 goto out_unlock;
293
294 if (sk->sk_state != TCP_CLOSE)
295 goto out_unlock;
296
297 bound_dev_if = sk->sk_bound_dev_if;
298
299 /* Check if the address belongs to the host. */
300 rcu_read_lock();
301 if (addr_type != IPV6_ADDR_ANY) {
302 struct net_device *dev = NULL;
303
304 if (addr_type & IPV6_ADDR_LINKLOCAL) {
305 if (addr->l2tp_scope_id)
306 bound_dev_if = addr->l2tp_scope_id;
307
308 /* Binding to link-local address requires an
309 * interface.
310 */
311 if (!bound_dev_if)
312 goto out_unlock_rcu;
313
314 err = -ENODEV;
315 dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
316 if (!dev)
317 goto out_unlock_rcu;
318 }
319
320 /* ipv4 addr of the socket is invalid. Only the
321 * unspecified and mapped address have a v4 equivalent.
322 */
323 v4addr = LOOPBACK4_IPV6;
324 err = -EADDRNOTAVAIL;
325 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
326 goto out_unlock_rcu;
327 }
328 rcu_read_unlock();
329
330 write_lock_bh(&l2tp_ip6_lock);
331 if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
332 addr->l2tp_conn_id)) {
333 write_unlock_bh(&l2tp_ip6_lock);
334 err = -EADDRINUSE;
335 goto out_unlock;
336 }
337
338 inet->inet_saddr = v4addr;
339 inet->inet_rcv_saddr = v4addr;
340 sk->sk_bound_dev_if = bound_dev_if;
341 sk->sk_v6_rcv_saddr = addr->l2tp_addr;
342 np->saddr = addr->l2tp_addr;
343
344 l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
345
346 sk_add_bind_node(sk, &l2tp_ip6_bind_table);
347 sk_del_node_init(sk);
348 write_unlock_bh(&l2tp_ip6_lock);
349
350 sock_reset_flag(sk, SOCK_ZAPPED);
351 release_sock(sk);
352 return 0;
353
354out_unlock_rcu:
355 rcu_read_unlock();
356out_unlock:
357 release_sock(sk);
358
359 return err;
360}
361
362static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
363 int addr_len)
364{
365 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
366 struct sockaddr_in6 *usin = (struct sockaddr_in6 *)uaddr;
367 struct in6_addr *daddr;
368 int addr_type;
369 int rc;
370
371 if (addr_len < sizeof(*lsa))
372 return -EINVAL;
373
374 if (usin->sin6_family != AF_INET6)
375 return -EINVAL;
376
377 addr_type = ipv6_addr_type(&usin->sin6_addr);
378 if (addr_type & IPV6_ADDR_MULTICAST)
379 return -EINVAL;
380
381 if (addr_type & IPV6_ADDR_MAPPED) {
382 daddr = &usin->sin6_addr;
383 if (ipv4_is_multicast(daddr->s6_addr32[3]))
384 return -EINVAL;
385 }
386
387 lock_sock(sk);
388
389 /* Must bind first - autobinding does not work */
390 if (sock_flag(sk, SOCK_ZAPPED)) {
391 rc = -EINVAL;
392 goto out_sk;
393 }
394
395 rc = __ip6_datagram_connect(sk, uaddr, addr_len);
396 if (rc < 0)
397 goto out_sk;
398
399 l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
400
401 write_lock_bh(&l2tp_ip6_lock);
402 hlist_del_init(&sk->sk_bind_node);
403 sk_add_bind_node(sk, &l2tp_ip6_bind_table);
404 write_unlock_bh(&l2tp_ip6_lock);
405
406out_sk:
407 release_sock(sk);
408
409 return rc;
410}
411
412static int l2tp_ip6_disconnect(struct sock *sk, int flags)
413{
414 if (sock_flag(sk, SOCK_ZAPPED))
415 return 0;
416
417 return __udp_disconnect(sk, flags);
418}
419
420static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
421 int peer)
422{
423 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
424 struct sock *sk = sock->sk;
425 struct ipv6_pinfo *np = inet6_sk(sk);
426 struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
427
428 lsa->l2tp_family = AF_INET6;
429 lsa->l2tp_flowinfo = 0;
430 lsa->l2tp_scope_id = 0;
431 lsa->l2tp_unused = 0;
432 if (peer) {
433 if (!lsk->peer_conn_id)
434 return -ENOTCONN;
435 lsa->l2tp_conn_id = lsk->peer_conn_id;
436 lsa->l2tp_addr = sk->sk_v6_daddr;
437 if (np->sndflow)
438 lsa->l2tp_flowinfo = np->flow_label;
439 } else {
440 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
441 lsa->l2tp_addr = np->saddr;
442 else
443 lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
444
445 lsa->l2tp_conn_id = lsk->conn_id;
446 }
447 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
448 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
449 return sizeof(*lsa);
450}
451
452static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
453{
454 int rc;
455
456 /* Charge it to the socket, dropping if the queue is full. */
457 rc = sock_queue_rcv_skb(sk, skb);
458 if (rc < 0)
459 goto drop;
460
461 return 0;
462
463drop:
464 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
465 kfree_skb(skb);
466 return -1;
467}
468
469static int l2tp_ip6_push_pending_frames(struct sock *sk)
470{
471 struct sk_buff *skb;
472 __be32 *transhdr = NULL;
473 int err = 0;
474
475 skb = skb_peek(&sk->sk_write_queue);
476 if (!skb)
477 goto out;
478
479 transhdr = (__be32 *)skb_transport_header(skb);
480 *transhdr = 0;
481
482 err = ip6_push_pending_frames(sk);
483
484out:
485 return err;
486}
487
488/* Userspace will call sendmsg() on the tunnel socket to send L2TP
489 * control frames.
490 */
491static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
492{
493 struct ipv6_txoptions opt_space;
494 DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
495 struct in6_addr *daddr, *final_p, final;
496 struct ipv6_pinfo *np = inet6_sk(sk);
497 struct ipv6_txoptions *opt_to_free = NULL;
498 struct ipv6_txoptions *opt = NULL;
499 struct ip6_flowlabel *flowlabel = NULL;
500 struct dst_entry *dst = NULL;
501 struct flowi6 fl6;
502 struct ipcm6_cookie ipc6;
503 int addr_len = msg->msg_namelen;
504 int transhdrlen = 4; /* zero session-id */
505 int ulen = len + transhdrlen;
506 int err;
507
508 /* Rough check on arithmetic overflow,
509 * better check is made in ip6_append_data().
510 */
511 if (len > INT_MAX)
512 return -EMSGSIZE;
513
514 /* Mirror BSD error message compatibility */
515 if (msg->msg_flags & MSG_OOB)
516 return -EOPNOTSUPP;
517
518 /* Get and verify the address */
519 memset(&fl6, 0, sizeof(fl6));
520
521 fl6.flowi6_mark = sk->sk_mark;
522 fl6.flowi6_uid = sk->sk_uid;
523
524 ipcm6_init(&ipc6);
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 (IS_ERR(flowlabel))
539 return -EINVAL;
540 }
541 }
542
543 /* Otherwise it will be difficult to maintain
544 * sk->sk_dst_cache.
545 */
546 if (sk->sk_state == TCP_ESTABLISHED &&
547 ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
548 daddr = &sk->sk_v6_daddr;
549
550 if (addr_len >= sizeof(struct sockaddr_in6) &&
551 lsa->l2tp_scope_id &&
552 ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
553 fl6.flowi6_oif = lsa->l2tp_scope_id;
554 } else {
555 if (sk->sk_state != TCP_ESTABLISHED)
556 return -EDESTADDRREQ;
557
558 daddr = &sk->sk_v6_daddr;
559 fl6.flowlabel = np->flow_label;
560 }
561
562 if (fl6.flowi6_oif == 0)
563 fl6.flowi6_oif = sk->sk_bound_dev_if;
564
565 if (msg->msg_controllen) {
566 opt = &opt_space;
567 memset(opt, 0, sizeof(struct ipv6_txoptions));
568 opt->tot_len = sizeof(struct ipv6_txoptions);
569 ipc6.opt = opt;
570
571 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6);
572 if (err < 0) {
573 fl6_sock_release(flowlabel);
574 return err;
575 }
576 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
577 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
578 if (IS_ERR(flowlabel))
579 return -EINVAL;
580 }
581 if (!(opt->opt_nflen | opt->opt_flen))
582 opt = NULL;
583 }
584
585 if (!opt) {
586 opt = txopt_get(np);
587 opt_to_free = opt;
588 }
589 if (flowlabel)
590 opt = fl6_merge_options(&opt_space, flowlabel, opt);
591 opt = ipv6_fixup_options(&opt_space, opt);
592 ipc6.opt = opt;
593
594 fl6.flowi6_proto = sk->sk_protocol;
595 if (!ipv6_addr_any(daddr))
596 fl6.daddr = *daddr;
597 else
598 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
599 if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
600 fl6.saddr = np->saddr;
601
602 final_p = fl6_update_dst(&fl6, opt, &final);
603
604 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
605 fl6.flowi6_oif = np->mcast_oif;
606 else if (!fl6.flowi6_oif)
607 fl6.flowi6_oif = np->ucast_oif;
608
609 security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));
610
611 if (ipc6.tclass < 0)
612 ipc6.tclass = np->tclass;
613
614 fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
615
616 dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl6, final_p);
617 if (IS_ERR(dst)) {
618 err = PTR_ERR(dst);
619 goto out;
620 }
621
622 if (ipc6.hlimit < 0)
623 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
624
625 if (ipc6.dontfrag < 0)
626 ipc6.dontfrag = np->dontfrag;
627
628 if (msg->msg_flags & MSG_CONFIRM)
629 goto do_confirm;
630
631back_from_confirm:
632 lock_sock(sk);
633 err = ip6_append_data(sk, ip_generic_getfrag, msg,
634 ulen, transhdrlen, &ipc6,
635 &fl6, (struct rt6_info *)dst,
636 msg->msg_flags);
637 if (err)
638 ip6_flush_pending_frames(sk);
639 else if (!(msg->msg_flags & MSG_MORE))
640 err = l2tp_ip6_push_pending_frames(sk);
641 release_sock(sk);
642done:
643 dst_release(dst);
644out:
645 fl6_sock_release(flowlabel);
646 txopt_put(opt_to_free);
647
648 return err < 0 ? err : len;
649
650do_confirm:
651 if (msg->msg_flags & MSG_PROBE)
652 dst_confirm_neigh(dst, &fl6.daddr);
653 if (!(msg->msg_flags & MSG_PROBE) || len)
654 goto back_from_confirm;
655 err = 0;
656 goto done;
657}
658
659static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
660 int noblock, int flags, int *addr_len)
661{
662 struct ipv6_pinfo *np = inet6_sk(sk);
663 DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
664 size_t copied = 0;
665 int err = -EOPNOTSUPP;
666 struct sk_buff *skb;
667
668 if (flags & MSG_OOB)
669 goto out;
670
671 if (flags & MSG_ERRQUEUE)
672 return ipv6_recv_error(sk, msg, len, addr_len);
673
674 skb = skb_recv_datagram(sk, flags, noblock, &err);
675 if (!skb)
676 goto out;
677
678 copied = skb->len;
679 if (len < copied) {
680 msg->msg_flags |= MSG_TRUNC;
681 copied = len;
682 }
683
684 err = skb_copy_datagram_msg(skb, 0, msg, copied);
685 if (err)
686 goto done;
687
688 sock_recv_timestamp(msg, sk, skb);
689
690 /* Copy the address. */
691 if (lsa) {
692 lsa->l2tp_family = AF_INET6;
693 lsa->l2tp_unused = 0;
694 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
695 lsa->l2tp_flowinfo = 0;
696 lsa->l2tp_scope_id = 0;
697 lsa->l2tp_conn_id = 0;
698 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
699 lsa->l2tp_scope_id = inet6_iif(skb);
700 *addr_len = sizeof(*lsa);
701 }
702
703 if (np->rxopt.all)
704 ip6_datagram_recv_ctl(sk, msg, skb);
705
706 if (flags & MSG_TRUNC)
707 copied = skb->len;
708done:
709 skb_free_datagram(sk, skb);
710out:
711 return err ? err : copied;
712}
713
714static struct proto l2tp_ip6_prot = {
715 .name = "L2TP/IPv6",
716 .owner = THIS_MODULE,
717 .init = l2tp_ip6_open,
718 .close = l2tp_ip6_close,
719 .bind = l2tp_ip6_bind,
720 .connect = l2tp_ip6_connect,
721 .disconnect = l2tp_ip6_disconnect,
722 .ioctl = l2tp_ioctl,
723 .destroy = l2tp_ip6_destroy_sock,
724 .setsockopt = ipv6_setsockopt,
725 .getsockopt = ipv6_getsockopt,
726 .sendmsg = l2tp_ip6_sendmsg,
727 .recvmsg = l2tp_ip6_recvmsg,
728 .backlog_rcv = l2tp_ip6_backlog_recv,
729 .hash = l2tp_ip6_hash,
730 .unhash = l2tp_ip6_unhash,
731 .obj_size = sizeof(struct l2tp_ip6_sock),
732};
733
734static const struct proto_ops l2tp_ip6_ops = {
735 .family = PF_INET6,
736 .owner = THIS_MODULE,
737 .release = inet6_release,
738 .bind = inet6_bind,
739 .connect = inet_dgram_connect,
740 .socketpair = sock_no_socketpair,
741 .accept = sock_no_accept,
742 .getname = l2tp_ip6_getname,
743 .poll = datagram_poll,
744 .ioctl = inet6_ioctl,
745 .gettstamp = sock_gettstamp,
746 .listen = sock_no_listen,
747 .shutdown = inet_shutdown,
748 .setsockopt = sock_common_setsockopt,
749 .getsockopt = sock_common_getsockopt,
750 .sendmsg = inet_sendmsg,
751 .recvmsg = sock_common_recvmsg,
752 .mmap = sock_no_mmap,
753 .sendpage = sock_no_sendpage,
754#ifdef CONFIG_COMPAT
755 .compat_ioctl = inet6_compat_ioctl,
756#endif
757};
758
759static struct inet_protosw l2tp_ip6_protosw = {
760 .type = SOCK_DGRAM,
761 .protocol = IPPROTO_L2TP,
762 .prot = &l2tp_ip6_prot,
763 .ops = &l2tp_ip6_ops,
764};
765
766static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
767 .handler = l2tp_ip6_recv,
768};
769
770static int __init l2tp_ip6_init(void)
771{
772 int err;
773
774 pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
775
776 err = proto_register(&l2tp_ip6_prot, 1);
777 if (err != 0)
778 goto out;
779
780 err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
781 if (err)
782 goto out1;
783
784 inet6_register_protosw(&l2tp_ip6_protosw);
785 return 0;
786
787out1:
788 proto_unregister(&l2tp_ip6_prot);
789out:
790 return err;
791}
792
793static void __exit l2tp_ip6_exit(void)
794{
795 inet6_unregister_protosw(&l2tp_ip6_protosw);
796 inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
797 proto_unregister(&l2tp_ip6_prot);
798}
799
800module_init(l2tp_ip6_init);
801module_exit(l2tp_ip6_exit);
802
803MODULE_LICENSE("GPL");
804MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
805MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
806MODULE_VERSION("1.0");
807
808/* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
809 * enums
810 */
811MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
812MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);