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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 <net/sock.h>
22#include <net/ip.h>
23#include <net/icmp.h>
24#include <net/udp.h>
25#include <net/inet_common.h>
26#include <net/inet_hashtables.h>
27#include <net/tcp_states.h>
28#include <net/protocol.h>
29#include <net/xfrm.h>
30
31#include "l2tp_core.h"
32
33struct l2tp_ip_sock {
34
35 struct inet_sock inet;
36
37 u32 conn_id;
38 u32 peer_conn_id;
39};
40
41static DEFINE_RWLOCK(l2tp_ip_lock);
42static struct hlist_head l2tp_ip_table;
43static struct hlist_head l2tp_ip_bind_table;
44
45static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
46{
47 return (struct l2tp_ip_sock *)sk;
48}
49
50static struct sock *__l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
51{
52 struct sock *sk;
53
54 sk_for_each_bound(sk, &l2tp_ip_bind_table) {
55 struct inet_sock *inet = inet_sk(sk);
56 struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
57
58 if (l2tp == NULL)
59 continue;
60
61 if ((l2tp->conn_id == tunnel_id) &&
62 net_eq(sock_net(sk), net) &&
63 !(inet->inet_rcv_saddr && inet->inet_rcv_saddr != laddr) &&
64 !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif))
65 goto found;
66 }
67
68 sk = NULL;
69found:
70 return sk;
71}
72
73static inline struct sock *l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
74{
75 struct sock *sk = __l2tp_ip_bind_lookup(net, laddr, dif, tunnel_id);
76 if (sk)
77 sock_hold(sk);
78
79 return sk;
80}
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115static int l2tp_ip_recv(struct sk_buff *skb)
116{
117 struct net *net = dev_net(skb->dev);
118 struct sock *sk;
119 u32 session_id;
120 u32 tunnel_id;
121 unsigned char *ptr, *optr;
122 struct l2tp_session *session;
123 struct l2tp_tunnel *tunnel = NULL;
124 int length;
125
126
127 optr = ptr = skb->data;
128
129 if (!pskb_may_pull(skb, 4))
130 goto discard;
131
132 session_id = ntohl(*((__be32 *) ptr));
133 ptr += 4;
134
135
136
137
138
139 if (session_id == 0) {
140 __skb_pull(skb, 4);
141 goto pass_up;
142 }
143
144
145 session = l2tp_session_find(net, NULL, session_id);
146 if (session == NULL)
147 goto discard;
148
149 tunnel = session->tunnel;
150 if (tunnel == NULL)
151 goto discard;
152
153
154 if (tunnel->debug & L2TP_MSG_DATA) {
155 length = min(32u, skb->len);
156 if (!pskb_may_pull(skb, length))
157 goto discard;
158
159 pr_debug("%s: ip recv\n", tunnel->name);
160 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
161 }
162
163 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook);
164
165 return 0;
166
167pass_up:
168
169 if (!pskb_may_pull(skb, 12))
170 goto discard;
171
172 if ((skb->data[0] & 0xc0) != 0xc0)
173 goto discard;
174
175 tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
176 tunnel = l2tp_tunnel_find(net, tunnel_id);
177 if (tunnel != NULL)
178 sk = tunnel->sock;
179 else {
180 struct iphdr *iph = (struct iphdr *) skb_network_header(skb);
181
182 read_lock_bh(&l2tp_ip_lock);
183 sk = __l2tp_ip_bind_lookup(net, iph->daddr, 0, tunnel_id);
184 read_unlock_bh(&l2tp_ip_lock);
185 }
186
187 if (sk == NULL)
188 goto discard;
189
190 sock_hold(sk);
191
192 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
193 goto discard_put;
194
195 nf_reset(skb);
196
197 return sk_receive_skb(sk, skb, 1);
198
199discard_put:
200 sock_put(sk);
201
202discard:
203 kfree_skb(skb);
204 return 0;
205}
206
207static int l2tp_ip_open(struct sock *sk)
208{
209
210 inet_sk(sk)->inet_num = IPPROTO_L2TP;
211
212 write_lock_bh(&l2tp_ip_lock);
213 sk_add_node(sk, &l2tp_ip_table);
214 write_unlock_bh(&l2tp_ip_lock);
215
216 return 0;
217}
218
219static void l2tp_ip_close(struct sock *sk, long timeout)
220{
221 write_lock_bh(&l2tp_ip_lock);
222 hlist_del_init(&sk->sk_bind_node);
223 sk_del_node_init(sk);
224 write_unlock_bh(&l2tp_ip_lock);
225 sk_common_release(sk);
226}
227
228static void l2tp_ip_destroy_sock(struct sock *sk)
229{
230 struct sk_buff *skb;
231 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
232
233 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
234 kfree_skb(skb);
235
236 if (tunnel) {
237 l2tp_tunnel_closeall(tunnel);
238 sock_put(sk);
239 }
240
241 sk_refcnt_debug_dec(sk);
242}
243
244static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
245{
246 struct inet_sock *inet = inet_sk(sk);
247 struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
248 struct net *net = sock_net(sk);
249 int ret;
250 int chk_addr_ret;
251
252 if (!sock_flag(sk, SOCK_ZAPPED))
253 return -EINVAL;
254 if (addr_len < sizeof(struct sockaddr_l2tpip))
255 return -EINVAL;
256 if (addr->l2tp_family != AF_INET)
257 return -EINVAL;
258
259 ret = -EADDRINUSE;
260 read_lock_bh(&l2tp_ip_lock);
261 if (__l2tp_ip_bind_lookup(net, addr->l2tp_addr.s_addr,
262 sk->sk_bound_dev_if, addr->l2tp_conn_id))
263 goto out_in_use;
264
265 read_unlock_bh(&l2tp_ip_lock);
266
267 lock_sock(sk);
268 if (sk->sk_state != TCP_CLOSE || addr_len < sizeof(struct sockaddr_l2tpip))
269 goto out;
270
271 chk_addr_ret = inet_addr_type(net, addr->l2tp_addr.s_addr);
272 ret = -EADDRNOTAVAIL;
273 if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
274 chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
275 goto out;
276
277 if (addr->l2tp_addr.s_addr)
278 inet->inet_rcv_saddr = inet->inet_saddr = addr->l2tp_addr.s_addr;
279 if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
280 inet->inet_saddr = 0;
281 sk_dst_reset(sk);
282
283 l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
284
285 write_lock_bh(&l2tp_ip_lock);
286 sk_add_bind_node(sk, &l2tp_ip_bind_table);
287 sk_del_node_init(sk);
288 write_unlock_bh(&l2tp_ip_lock);
289 ret = 0;
290 sock_reset_flag(sk, SOCK_ZAPPED);
291
292out:
293 release_sock(sk);
294
295 return ret;
296
297out_in_use:
298 read_unlock_bh(&l2tp_ip_lock);
299
300 return ret;
301}
302
303static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
304{
305 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
306 int rc;
307
308 if (sock_flag(sk, SOCK_ZAPPED))
309 return -EINVAL;
310
311 if (addr_len < sizeof(*lsa))
312 return -EINVAL;
313
314 if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
315 return -EINVAL;
316
317 rc = ip4_datagram_connect(sk, uaddr, addr_len);
318 if (rc < 0)
319 return rc;
320
321 lock_sock(sk);
322
323 l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
324
325 write_lock_bh(&l2tp_ip_lock);
326 hlist_del_init(&sk->sk_bind_node);
327 sk_add_bind_node(sk, &l2tp_ip_bind_table);
328 write_unlock_bh(&l2tp_ip_lock);
329
330 release_sock(sk);
331 return rc;
332}
333
334static int l2tp_ip_disconnect(struct sock *sk, int flags)
335{
336 if (sock_flag(sk, SOCK_ZAPPED))
337 return 0;
338
339 return udp_disconnect(sk, flags);
340}
341
342static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
343 int *uaddr_len, int peer)
344{
345 struct sock *sk = sock->sk;
346 struct inet_sock *inet = inet_sk(sk);
347 struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
348 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
349
350 memset(lsa, 0, sizeof(*lsa));
351 lsa->l2tp_family = AF_INET;
352 if (peer) {
353 if (!inet->inet_dport)
354 return -ENOTCONN;
355 lsa->l2tp_conn_id = lsk->peer_conn_id;
356 lsa->l2tp_addr.s_addr = inet->inet_daddr;
357 } else {
358 __be32 addr = inet->inet_rcv_saddr;
359 if (!addr)
360 addr = inet->inet_saddr;
361 lsa->l2tp_conn_id = lsk->conn_id;
362 lsa->l2tp_addr.s_addr = addr;
363 }
364 *uaddr_len = sizeof(*lsa);
365 return 0;
366}
367
368static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
369{
370 int rc;
371
372
373 rc = sock_queue_rcv_skb(sk, skb);
374 if (rc < 0)
375 goto drop;
376
377 return 0;
378
379drop:
380 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
381 kfree_skb(skb);
382 return -1;
383}
384
385
386
387
388static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len)
389{
390 struct sk_buff *skb;
391 int rc;
392 struct inet_sock *inet = inet_sk(sk);
393 struct rtable *rt = NULL;
394 struct flowi4 *fl4;
395 int connected = 0;
396 __be32 daddr;
397
398 lock_sock(sk);
399
400 rc = -ENOTCONN;
401 if (sock_flag(sk, SOCK_DEAD))
402 goto out;
403
404
405 if (msg->msg_name) {
406 struct sockaddr_l2tpip *lip = (struct sockaddr_l2tpip *) msg->msg_name;
407 rc = -EINVAL;
408 if (msg->msg_namelen < sizeof(*lip))
409 goto out;
410
411 if (lip->l2tp_family != AF_INET) {
412 rc = -EAFNOSUPPORT;
413 if (lip->l2tp_family != AF_UNSPEC)
414 goto out;
415 }
416
417 daddr = lip->l2tp_addr.s_addr;
418 } else {
419 rc = -EDESTADDRREQ;
420 if (sk->sk_state != TCP_ESTABLISHED)
421 goto out;
422
423 daddr = inet->inet_daddr;
424 connected = 1;
425 }
426
427
428 rc = -ENOMEM;
429 skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
430 4 + len, 0, GFP_KERNEL);
431 if (!skb)
432 goto error;
433
434
435 skb_reserve(skb, 2 + NET_SKB_PAD);
436 skb_reset_network_header(skb);
437 skb_reserve(skb, sizeof(struct iphdr));
438 skb_reset_transport_header(skb);
439
440
441 *((__be32 *) skb_put(skb, 4)) = 0;
442
443
444 rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
445 if (rc < 0) {
446 kfree_skb(skb);
447 goto error;
448 }
449
450 fl4 = &inet->cork.fl.u.ip4;
451 if (connected)
452 rt = (struct rtable *) __sk_dst_check(sk, 0);
453
454 rcu_read_lock();
455 if (rt == NULL) {
456 const struct ip_options_rcu *inet_opt;
457
458 inet_opt = rcu_dereference(inet->inet_opt);
459
460
461 if (inet_opt && inet_opt->opt.srr)
462 daddr = inet_opt->opt.faddr;
463
464
465
466
467
468 rt = ip_route_output_ports(sock_net(sk), fl4, sk,
469 daddr, inet->inet_saddr,
470 inet->inet_dport, inet->inet_sport,
471 sk->sk_protocol, RT_CONN_FLAGS(sk),
472 sk->sk_bound_dev_if);
473 if (IS_ERR(rt))
474 goto no_route;
475 if (connected) {
476 sk_setup_caps(sk, &rt->dst);
477 } else {
478 skb_dst_set(skb, &rt->dst);
479 goto xmit;
480 }
481 }
482
483
484
485
486 skb_dst_set_noref(skb, &rt->dst);
487
488xmit:
489
490 rc = ip_queue_xmit(skb, &inet->cork.fl);
491 rcu_read_unlock();
492
493error:
494 if (rc >= 0)
495 rc = len;
496
497out:
498 release_sock(sk);
499 return rc;
500
501no_route:
502 rcu_read_unlock();
503 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
504 kfree_skb(skb);
505 rc = -EHOSTUNREACH;
506 goto out;
507}
508
509static int l2tp_ip_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
510 size_t len, int noblock, int flags, int *addr_len)
511{
512 struct inet_sock *inet = inet_sk(sk);
513 size_t copied = 0;
514 int err = -EOPNOTSUPP;
515 struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
516 struct sk_buff *skb;
517
518 if (flags & MSG_OOB)
519 goto out;
520
521 if (addr_len)
522 *addr_len = sizeof(*sin);
523
524 skb = skb_recv_datagram(sk, flags, noblock, &err);
525 if (!skb)
526 goto out;
527
528 copied = skb->len;
529 if (len < copied) {
530 msg->msg_flags |= MSG_TRUNC;
531 copied = len;
532 }
533
534 err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
535 if (err)
536 goto done;
537
538 sock_recv_timestamp(msg, sk, skb);
539
540
541 if (sin) {
542 sin->sin_family = AF_INET;
543 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
544 sin->sin_port = 0;
545 memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
546 }
547 if (inet->cmsg_flags)
548 ip_cmsg_recv(msg, skb);
549 if (flags & MSG_TRUNC)
550 copied = skb->len;
551done:
552 skb_free_datagram(sk, skb);
553out:
554 return err ? err : copied;
555}
556
557static struct proto l2tp_ip_prot = {
558 .name = "L2TP/IP",
559 .owner = THIS_MODULE,
560 .init = l2tp_ip_open,
561 .close = l2tp_ip_close,
562 .bind = l2tp_ip_bind,
563 .connect = l2tp_ip_connect,
564 .disconnect = l2tp_ip_disconnect,
565 .ioctl = udp_ioctl,
566 .destroy = l2tp_ip_destroy_sock,
567 .setsockopt = ip_setsockopt,
568 .getsockopt = ip_getsockopt,
569 .sendmsg = l2tp_ip_sendmsg,
570 .recvmsg = l2tp_ip_recvmsg,
571 .backlog_rcv = l2tp_ip_backlog_recv,
572 .hash = inet_hash,
573 .unhash = inet_unhash,
574 .obj_size = sizeof(struct l2tp_ip_sock),
575#ifdef CONFIG_COMPAT
576 .compat_setsockopt = compat_ip_setsockopt,
577 .compat_getsockopt = compat_ip_getsockopt,
578#endif
579};
580
581static const struct proto_ops l2tp_ip_ops = {
582 .family = PF_INET,
583 .owner = THIS_MODULE,
584 .release = inet_release,
585 .bind = inet_bind,
586 .connect = inet_dgram_connect,
587 .socketpair = sock_no_socketpair,
588 .accept = sock_no_accept,
589 .getname = l2tp_ip_getname,
590 .poll = datagram_poll,
591 .ioctl = inet_ioctl,
592 .listen = sock_no_listen,
593 .shutdown = inet_shutdown,
594 .setsockopt = sock_common_setsockopt,
595 .getsockopt = sock_common_getsockopt,
596 .sendmsg = inet_sendmsg,
597 .recvmsg = sock_common_recvmsg,
598 .mmap = sock_no_mmap,
599 .sendpage = sock_no_sendpage,
600#ifdef CONFIG_COMPAT
601 .compat_setsockopt = compat_sock_common_setsockopt,
602 .compat_getsockopt = compat_sock_common_getsockopt,
603#endif
604};
605
606static struct inet_protosw l2tp_ip_protosw = {
607 .type = SOCK_DGRAM,
608 .protocol = IPPROTO_L2TP,
609 .prot = &l2tp_ip_prot,
610 .ops = &l2tp_ip_ops,
611 .no_check = 0,
612};
613
614static struct net_protocol l2tp_ip_protocol __read_mostly = {
615 .handler = l2tp_ip_recv,
616 .netns_ok = 1,
617};
618
619static int __init l2tp_ip_init(void)
620{
621 int err;
622
623 pr_info("L2TP IP encapsulation support (L2TPv3)\n");
624
625 err = proto_register(&l2tp_ip_prot, 1);
626 if (err != 0)
627 goto out;
628
629 err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
630 if (err)
631 goto out1;
632
633 inet_register_protosw(&l2tp_ip_protosw);
634 return 0;
635
636out1:
637 proto_unregister(&l2tp_ip_prot);
638out:
639 return err;
640}
641
642static void __exit l2tp_ip_exit(void)
643{
644 inet_unregister_protosw(&l2tp_ip_protosw);
645 inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
646 proto_unregister(&l2tp_ip_prot);
647}
648
649module_init(l2tp_ip_init);
650module_exit(l2tp_ip_exit);
651
652MODULE_LICENSE("GPL");
653MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
654MODULE_DESCRIPTION("L2TP over IP");
655MODULE_VERSION("1.0");
656
657
658
659
660MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP);
661
