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12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <asm/ioctls.h>
15#include <linux/icmp.h>
16#include <linux/module.h>
17#include <linux/skbuff.h>
18#include <linux/random.h>
19#include <linux/socket.h>
20#include <linux/l2tp.h>
21#include <linux/in.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/tcp_states.h>
29#include <net/protocol.h>
30#include <net/xfrm.h>
31
32#include "l2tp_core.h"
33
34struct l2tp_ip_sock {
35
36 struct inet_sock inet;
37
38 u32 conn_id;
39 u32 peer_conn_id;
40};
41
42static DEFINE_RWLOCK(l2tp_ip_lock);
43static struct hlist_head l2tp_ip_table;
44static struct hlist_head l2tp_ip_bind_table;
45
46static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
47{
48 return (struct l2tp_ip_sock *)sk;
49}
50
51static struct sock *__l2tp_ip_bind_lookup(const struct net *net, __be32 laddr,
52 __be32 raddr, int dif, u32 tunnel_id)
53{
54 struct sock *sk;
55
56 sk_for_each_bound(sk, &l2tp_ip_bind_table) {
57 const struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
58 const struct inet_sock *inet = inet_sk(sk);
59
60 if (!net_eq(sock_net(sk), net))
61 continue;
62
63 if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
64 continue;
65
66 if (inet->inet_rcv_saddr && laddr &&
67 inet->inet_rcv_saddr != laddr)
68 continue;
69
70 if (inet->inet_daddr && raddr && inet->inet_daddr != raddr)
71 continue;
72
73 if (l2tp->conn_id != tunnel_id)
74 continue;
75
76 goto found;
77 }
78
79 sk = NULL;
80found:
81 return sk;
82}
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116
117static int l2tp_ip_recv(struct sk_buff *skb)
118{
119 struct net *net = dev_net(skb->dev);
120 struct sock *sk;
121 u32 session_id;
122 u32 tunnel_id;
123 unsigned char *ptr, *optr;
124 struct l2tp_session *session;
125 struct l2tp_tunnel *tunnel = NULL;
126 struct iphdr *iph;
127 int length;
128
129 if (!pskb_may_pull(skb, 4))
130 goto discard;
131
132
133 optr = ptr = skb->data;
134 session_id = ntohl(*((__be32 *) ptr));
135 ptr += 4;
136
137
138
139
140
141 if (session_id == 0) {
142 __skb_pull(skb, 4);
143 goto pass_up;
144 }
145
146
147 session = l2tp_session_get(net, NULL, session_id, true);
148 if (!session)
149 goto discard;
150
151 tunnel = session->tunnel;
152 if (!tunnel)
153 goto discard_sess;
154
155
156 if (tunnel->debug & L2TP_MSG_DATA) {
157 length = min(32u, skb->len);
158 if (!pskb_may_pull(skb, length))
159 goto discard_sess;
160
161
162 optr = ptr = skb->data;
163 ptr += 4;
164 pr_debug("%s: ip recv\n", tunnel->name);
165 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
166 }
167
168 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook);
169 l2tp_session_dec_refcount(session);
170
171 return 0;
172
173pass_up:
174
175 if (!pskb_may_pull(skb, 12))
176 goto discard;
177
178 if ((skb->data[0] & 0xc0) != 0xc0)
179 goto discard;
180
181 tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
182 iph = (struct iphdr *)skb_network_header(skb);
183
184 read_lock_bh(&l2tp_ip_lock);
185 sk = __l2tp_ip_bind_lookup(net, iph->daddr, iph->saddr, inet_iif(skb),
186 tunnel_id);
187 if (!sk) {
188 read_unlock_bh(&l2tp_ip_lock);
189 goto discard;
190 }
191 sock_hold(sk);
192 read_unlock_bh(&l2tp_ip_lock);
193
194 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
195 goto discard_put;
196
197 nf_reset(skb);
198
199 return sk_receive_skb(sk, skb, 1);
200
201discard_sess:
202 if (session->deref)
203 session->deref(session);
204 l2tp_session_dec_refcount(session);
205 goto discard;
206
207discard_put:
208 sock_put(sk);
209
210discard:
211 kfree_skb(skb);
212 return 0;
213}
214
215static int l2tp_ip_open(struct sock *sk)
216{
217
218 inet_sk(sk)->inet_num = IPPROTO_L2TP;
219
220 write_lock_bh(&l2tp_ip_lock);
221 sk_add_node(sk, &l2tp_ip_table);
222 write_unlock_bh(&l2tp_ip_lock);
223
224 return 0;
225}
226
227static void l2tp_ip_close(struct sock *sk, long timeout)
228{
229 write_lock_bh(&l2tp_ip_lock);
230 hlist_del_init(&sk->sk_bind_node);
231 sk_del_node_init(sk);
232 write_unlock_bh(&l2tp_ip_lock);
233 sk_common_release(sk);
234}
235
236static void l2tp_ip_destroy_sock(struct sock *sk)
237{
238 struct sk_buff *skb;
239 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
240
241 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
242 kfree_skb(skb);
243
244 if (tunnel) {
245 l2tp_tunnel_closeall(tunnel);
246 sock_put(sk);
247 }
248
249 sk_refcnt_debug_dec(sk);
250}
251
252static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
253{
254 struct inet_sock *inet = inet_sk(sk);
255 struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
256 struct net *net = sock_net(sk);
257 int ret;
258 int chk_addr_ret;
259
260 if (addr_len < sizeof(struct sockaddr_l2tpip))
261 return -EINVAL;
262 if (addr->l2tp_family != AF_INET)
263 return -EINVAL;
264
265 lock_sock(sk);
266
267 ret = -EINVAL;
268 if (!sock_flag(sk, SOCK_ZAPPED))
269 goto out;
270
271 if (sk->sk_state != TCP_CLOSE)
272 goto out;
273
274 chk_addr_ret = inet_addr_type(net, addr->l2tp_addr.s_addr);
275 ret = -EADDRNOTAVAIL;
276 if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
277 chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
278 goto out;
279
280 if (addr->l2tp_addr.s_addr)
281 inet->inet_rcv_saddr = inet->inet_saddr = addr->l2tp_addr.s_addr;
282 if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
283 inet->inet_saddr = 0;
284
285 write_lock_bh(&l2tp_ip_lock);
286 if (__l2tp_ip_bind_lookup(net, addr->l2tp_addr.s_addr, 0,
287 sk->sk_bound_dev_if, addr->l2tp_conn_id)) {
288 write_unlock_bh(&l2tp_ip_lock);
289 ret = -EADDRINUSE;
290 goto out;
291 }
292
293 sk_dst_reset(sk);
294 l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
295
296 sk_add_bind_node(sk, &l2tp_ip_bind_table);
297 sk_del_node_init(sk);
298 write_unlock_bh(&l2tp_ip_lock);
299
300 ret = 0;
301 sock_reset_flag(sk, SOCK_ZAPPED);
302
303out:
304 release_sock(sk);
305
306 return ret;
307}
308
309static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
310{
311 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
312 int rc;
313
314 if (addr_len < sizeof(*lsa))
315 return -EINVAL;
316
317 if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
318 return -EINVAL;
319
320 lock_sock(sk);
321
322
323 if (sock_flag(sk, SOCK_ZAPPED)) {
324 rc = -EINVAL;
325 goto out_sk;
326 }
327
328 rc = __ip4_datagram_connect(sk, uaddr, addr_len);
329 if (rc < 0)
330 goto out_sk;
331
332 l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
333
334 write_lock_bh(&l2tp_ip_lock);
335 hlist_del_init(&sk->sk_bind_node);
336 sk_add_bind_node(sk, &l2tp_ip_bind_table);
337 write_unlock_bh(&l2tp_ip_lock);
338
339out_sk:
340 release_sock(sk);
341
342 return rc;
343}
344
345static int l2tp_ip_disconnect(struct sock *sk, int flags)
346{
347 if (sock_flag(sk, SOCK_ZAPPED))
348 return 0;
349
350 return __udp_disconnect(sk, flags);
351}
352
353static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
354 int *uaddr_len, int peer)
355{
356 struct sock *sk = sock->sk;
357 struct inet_sock *inet = inet_sk(sk);
358 struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
359 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
360
361 memset(lsa, 0, sizeof(*lsa));
362 lsa->l2tp_family = AF_INET;
363 if (peer) {
364 if (!inet->inet_dport)
365 return -ENOTCONN;
366 lsa->l2tp_conn_id = lsk->peer_conn_id;
367 lsa->l2tp_addr.s_addr = inet->inet_daddr;
368 } else {
369 __be32 addr = inet->inet_rcv_saddr;
370 if (!addr)
371 addr = inet->inet_saddr;
372 lsa->l2tp_conn_id = lsk->conn_id;
373 lsa->l2tp_addr.s_addr = addr;
374 }
375 *uaddr_len = sizeof(*lsa);
376 return 0;
377}
378
379static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
380{
381 int rc;
382
383
384 rc = sock_queue_rcv_skb(sk, skb);
385 if (rc < 0)
386 goto drop;
387
388 return 0;
389
390drop:
391 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
392 kfree_skb(skb);
393 return 0;
394}
395
396
397
398
399static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
400{
401 struct sk_buff *skb;
402 int rc;
403 struct inet_sock *inet = inet_sk(sk);
404 struct rtable *rt = NULL;
405 struct flowi4 *fl4;
406 int connected = 0;
407 __be32 daddr;
408
409 lock_sock(sk);
410
411 rc = -ENOTCONN;
412 if (sock_flag(sk, SOCK_DEAD))
413 goto out;
414
415
416 if (msg->msg_name) {
417 DECLARE_SOCKADDR(struct sockaddr_l2tpip *, lip, msg->msg_name);
418 rc = -EINVAL;
419 if (msg->msg_namelen < sizeof(*lip))
420 goto out;
421
422 if (lip->l2tp_family != AF_INET) {
423 rc = -EAFNOSUPPORT;
424 if (lip->l2tp_family != AF_UNSPEC)
425 goto out;
426 }
427
428 daddr = lip->l2tp_addr.s_addr;
429 } else {
430 rc = -EDESTADDRREQ;
431 if (sk->sk_state != TCP_ESTABLISHED)
432 goto out;
433
434 daddr = inet->inet_daddr;
435 connected = 1;
436 }
437
438
439 rc = -ENOMEM;
440 skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
441 4 + len, 0, GFP_KERNEL);
442 if (!skb)
443 goto error;
444
445
446 skb_reserve(skb, 2 + NET_SKB_PAD);
447 skb_reset_network_header(skb);
448 skb_reserve(skb, sizeof(struct iphdr));
449 skb_reset_transport_header(skb);
450
451
452 *((__be32 *) skb_put(skb, 4)) = 0;
453
454
455 rc = memcpy_from_msg(skb_put(skb, len), msg, len);
456 if (rc < 0) {
457 kfree_skb(skb);
458 goto error;
459 }
460
461 fl4 = &inet->cork.fl.u.ip4;
462 if (connected)
463 rt = (struct rtable *) __sk_dst_check(sk, 0);
464
465 rcu_read_lock();
466 if (rt == NULL) {
467 const struct ip_options_rcu *inet_opt;
468
469 inet_opt = rcu_dereference(inet->inet_opt);
470
471
472 if (inet_opt && inet_opt->opt.srr)
473 daddr = inet_opt->opt.faddr;
474
475
476
477
478
479 rt = ip_route_output_ports(sock_net(sk), fl4, sk,
480 daddr, inet->inet_saddr,
481 inet->inet_dport, inet->inet_sport,
482 sk->sk_protocol, RT_CONN_FLAGS(sk),
483 sk->sk_bound_dev_if);
484 if (IS_ERR(rt))
485 goto no_route;
486 if (connected) {
487 sk_setup_caps(sk, &rt->dst);
488 } else {
489 skb_dst_set(skb, &rt->dst);
490 goto xmit;
491 }
492 }
493
494
495
496
497 skb_dst_set_noref(skb, &rt->dst);
498
499xmit:
500
501 rc = ip_queue_xmit(sk, skb, &inet->cork.fl);
502 rcu_read_unlock();
503
504error:
505 if (rc >= 0)
506 rc = len;
507
508out:
509 release_sock(sk);
510 return rc;
511
512no_route:
513 rcu_read_unlock();
514 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
515 kfree_skb(skb);
516 rc = -EHOSTUNREACH;
517 goto out;
518}
519
520static int l2tp_ip_recvmsg(struct sock *sk, struct msghdr *msg,
521 size_t len, int noblock, int flags, int *addr_len)
522{
523 struct inet_sock *inet = inet_sk(sk);
524 size_t copied = 0;
525 int err = -EOPNOTSUPP;
526 DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
527 struct sk_buff *skb;
528
529 if (flags & MSG_OOB)
530 goto out;
531
532 skb = skb_recv_datagram(sk, flags, noblock, &err);
533 if (!skb)
534 goto out;
535
536 copied = skb->len;
537 if (len < copied) {
538 msg->msg_flags |= MSG_TRUNC;
539 copied = len;
540 }
541
542 err = skb_copy_datagram_msg(skb, 0, msg, copied);
543 if (err)
544 goto done;
545
546 sock_recv_timestamp(msg, sk, skb);
547
548
549 if (sin) {
550 sin->sin_family = AF_INET;
551 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
552 sin->sin_port = 0;
553 memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
554 *addr_len = sizeof(*sin);
555 }
556 if (inet->cmsg_flags)
557 ip_cmsg_recv(msg, skb);
558 if (flags & MSG_TRUNC)
559 copied = skb->len;
560done:
561 skb_free_datagram(sk, skb);
562out:
563 return err ? err : copied;
564}
565
566int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg)
567{
568 struct sk_buff *skb;
569 int amount;
570
571 switch (cmd) {
572 case SIOCOUTQ:
573 amount = sk_wmem_alloc_get(sk);
574 break;
575 case SIOCINQ:
576 spin_lock_bh(&sk->sk_receive_queue.lock);
577 skb = skb_peek(&sk->sk_receive_queue);
578 amount = skb ? skb->len : 0;
579 spin_unlock_bh(&sk->sk_receive_queue.lock);
580 break;
581
582 default:
583 return -ENOIOCTLCMD;
584 }
585
586 return put_user(amount, (int __user *)arg);
587}
588EXPORT_SYMBOL(l2tp_ioctl);
589
590static struct proto l2tp_ip_prot = {
591 .name = "L2TP/IP",
592 .owner = THIS_MODULE,
593 .init = l2tp_ip_open,
594 .close = l2tp_ip_close,
595 .bind = l2tp_ip_bind,
596 .connect = l2tp_ip_connect,
597 .disconnect = l2tp_ip_disconnect,
598 .ioctl = l2tp_ioctl,
599 .destroy = l2tp_ip_destroy_sock,
600 .setsockopt = ip_setsockopt,
601 .getsockopt = ip_getsockopt,
602 .sendmsg = l2tp_ip_sendmsg,
603 .recvmsg = l2tp_ip_recvmsg,
604 .backlog_rcv = l2tp_ip_backlog_recv,
605 .hash = inet_hash,
606 .unhash = inet_unhash,
607 .obj_size = sizeof(struct l2tp_ip_sock),
608#ifdef CONFIG_COMPAT
609 .compat_setsockopt = compat_ip_setsockopt,
610 .compat_getsockopt = compat_ip_getsockopt,
611#endif
612};
613
614static const struct proto_ops l2tp_ip_ops = {
615 .family = PF_INET,
616 .owner = THIS_MODULE,
617 .release = inet_release,
618 .bind = inet_bind,
619 .connect = inet_dgram_connect,
620 .socketpair = sock_no_socketpair,
621 .accept = sock_no_accept,
622 .getname = l2tp_ip_getname,
623 .poll = datagram_poll,
624 .ioctl = inet_ioctl,
625 .listen = sock_no_listen,
626 .shutdown = inet_shutdown,
627 .setsockopt = sock_common_setsockopt,
628 .getsockopt = sock_common_getsockopt,
629 .sendmsg = inet_sendmsg,
630 .recvmsg = sock_common_recvmsg,
631 .mmap = sock_no_mmap,
632 .sendpage = sock_no_sendpage,
633#ifdef CONFIG_COMPAT
634 .compat_setsockopt = compat_sock_common_setsockopt,
635 .compat_getsockopt = compat_sock_common_getsockopt,
636#endif
637};
638
639static struct inet_protosw l2tp_ip_protosw = {
640 .type = SOCK_DGRAM,
641 .protocol = IPPROTO_L2TP,
642 .prot = &l2tp_ip_prot,
643 .ops = &l2tp_ip_ops,
644};
645
646static struct net_protocol l2tp_ip_protocol __read_mostly = {
647 .handler = l2tp_ip_recv,
648 .netns_ok = 1,
649};
650
651static int __init l2tp_ip_init(void)
652{
653 int err;
654
655 pr_info("L2TP IP encapsulation support (L2TPv3)\n");
656
657 err = proto_register(&l2tp_ip_prot, 1);
658 if (err != 0)
659 goto out;
660
661 err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
662 if (err)
663 goto out1;
664
665 inet_register_protosw(&l2tp_ip_protosw);
666 return 0;
667
668out1:
669 proto_unregister(&l2tp_ip_prot);
670out:
671 return err;
672}
673
674static void __exit l2tp_ip_exit(void)
675{
676 inet_unregister_protosw(&l2tp_ip_protosw);
677 inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
678 proto_unregister(&l2tp_ip_prot);
679}
680
681module_init(l2tp_ip_init);
682module_exit(l2tp_ip_exit);
683
684MODULE_LICENSE("GPL");
685MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
686MODULE_DESCRIPTION("L2TP over IP");
687MODULE_VERSION("1.0");
688
689
690
691
692MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP);
693MODULE_ALIAS_NET_PF_PROTO(PF_INET, IPPROTO_L2TP);
694
