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7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <asm/ioctls.h>
10#include <linux/icmp.h>
11#include <linux/module.h>
12#include <linux/skbuff.h>
13#include <linux/random.h>
14#include <linux/socket.h>
15#include <linux/l2tp.h>
16#include <linux/in.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 "l2tp_core.h"
27
28struct l2tp_ip_sock {
29
30 struct inet_sock inet;
31
32 u32 conn_id;
33 u32 peer_conn_id;
34};
35
36static DEFINE_RWLOCK(l2tp_ip_lock);
37static struct hlist_head l2tp_ip_table;
38static struct hlist_head l2tp_ip_bind_table;
39
40static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
41{
42 return (struct l2tp_ip_sock *)sk;
43}
44
45static struct sock *__l2tp_ip_bind_lookup(const struct net *net, __be32 laddr,
46 __be32 raddr, int dif, u32 tunnel_id)
47{
48 struct sock *sk;
49
50 sk_for_each_bound(sk, &l2tp_ip_bind_table) {
51 const struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
52 const struct inet_sock *inet = inet_sk(sk);
53
54 if (!net_eq(sock_net(sk), net))
55 continue;
56
57 if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
58 continue;
59
60 if (inet->inet_rcv_saddr && laddr &&
61 inet->inet_rcv_saddr != laddr)
62 continue;
63
64 if (inet->inet_daddr && raddr && inet->inet_daddr != raddr)
65 continue;
66
67 if (l2tp->conn_id != tunnel_id)
68 continue;
69
70 goto found;
71 }
72
73 sk = NULL;
74found:
75 return sk;
76}
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110
111static int l2tp_ip_recv(struct sk_buff *skb)
112{
113 struct net *net = dev_net(skb->dev);
114 struct sock *sk;
115 u32 session_id;
116 u32 tunnel_id;
117 unsigned char *ptr, *optr;
118 struct l2tp_session *session;
119 struct l2tp_tunnel *tunnel = NULL;
120 struct iphdr *iph;
121
122 if (!pskb_may_pull(skb, 4))
123 goto discard;
124
125
126 optr = skb->data;
127 ptr = skb->data;
128 session_id = ntohl(*((__be32 *)ptr));
129 ptr += 4;
130
131
132
133
134
135 if (session_id == 0) {
136 __skb_pull(skb, 4);
137 goto pass_up;
138 }
139
140
141 session = l2tp_session_get(net, session_id);
142 if (!session)
143 goto discard;
144
145 tunnel = session->tunnel;
146 if (!tunnel)
147 goto discard_sess;
148
149 if (l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
150 goto discard_sess;
151
152 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len);
153 l2tp_session_dec_refcount(session);
154
155 return 0;
156
157pass_up:
158
159 if (!pskb_may_pull(skb, 12))
160 goto discard;
161
162 if ((skb->data[0] & 0xc0) != 0xc0)
163 goto discard;
164
165 tunnel_id = ntohl(*(__be32 *)&skb->data[4]);
166 iph = (struct iphdr *)skb_network_header(skb);
167
168 read_lock_bh(&l2tp_ip_lock);
169 sk = __l2tp_ip_bind_lookup(net, iph->daddr, iph->saddr, inet_iif(skb),
170 tunnel_id);
171 if (!sk) {
172 read_unlock_bh(&l2tp_ip_lock);
173 goto discard;
174 }
175 sock_hold(sk);
176 read_unlock_bh(&l2tp_ip_lock);
177
178 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
179 goto discard_put;
180
181 nf_reset_ct(skb);
182
183 return sk_receive_skb(sk, skb, 1);
184
185discard_sess:
186 l2tp_session_dec_refcount(session);
187 goto discard;
188
189discard_put:
190 sock_put(sk);
191
192discard:
193 kfree_skb(skb);
194 return 0;
195}
196
197static int l2tp_ip_hash(struct sock *sk)
198{
199 if (sk_unhashed(sk)) {
200 write_lock_bh(&l2tp_ip_lock);
201 sk_add_node(sk, &l2tp_ip_table);
202 write_unlock_bh(&l2tp_ip_lock);
203 }
204 return 0;
205}
206
207static void l2tp_ip_unhash(struct sock *sk)
208{
209 if (sk_unhashed(sk))
210 return;
211 write_lock_bh(&l2tp_ip_lock);
212 sk_del_node_init(sk);
213 write_unlock_bh(&l2tp_ip_lock);
214}
215
216static int l2tp_ip_open(struct sock *sk)
217{
218
219 inet_sk(sk)->inet_num = IPPROTO_L2TP;
220
221 l2tp_ip_hash(sk);
222 return 0;
223}
224
225static void l2tp_ip_close(struct sock *sk, long timeout)
226{
227 write_lock_bh(&l2tp_ip_lock);
228 hlist_del_init(&sk->sk_bind_node);
229 sk_del_node_init(sk);
230 write_unlock_bh(&l2tp_ip_lock);
231 sk_common_release(sk);
232}
233
234static void l2tp_ip_destroy_sock(struct sock *sk)
235{
236 struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
237 struct sk_buff *skb;
238
239 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
240 kfree_skb(skb);
241
242 if (tunnel)
243 l2tp_tunnel_delete(tunnel);
244}
245
246static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
247{
248 struct inet_sock *inet = inet_sk(sk);
249 struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *)uaddr;
250 struct net *net = sock_net(sk);
251 int ret;
252 int chk_addr_ret;
253
254 if (addr_len < sizeof(struct sockaddr_l2tpip))
255 return -EINVAL;
256 if (addr->l2tp_family != AF_INET)
257 return -EINVAL;
258
259 lock_sock(sk);
260
261 ret = -EINVAL;
262 if (!sock_flag(sk, SOCK_ZAPPED))
263 goto out;
264
265 if (sk->sk_state != TCP_CLOSE)
266 goto out;
267
268 chk_addr_ret = inet_addr_type(net, addr->l2tp_addr.s_addr);
269 ret = -EADDRNOTAVAIL;
270 if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
271 chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
272 goto out;
273
274 if (addr->l2tp_addr.s_addr) {
275 inet->inet_rcv_saddr = addr->l2tp_addr.s_addr;
276 inet->inet_saddr = addr->l2tp_addr.s_addr;
277 }
278 if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
279 inet->inet_saddr = 0;
280
281 write_lock_bh(&l2tp_ip_lock);
282 if (__l2tp_ip_bind_lookup(net, addr->l2tp_addr.s_addr, 0,
283 sk->sk_bound_dev_if, addr->l2tp_conn_id)) {
284 write_unlock_bh(&l2tp_ip_lock);
285 ret = -EADDRINUSE;
286 goto out;
287 }
288
289 sk_dst_reset(sk);
290 l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
291
292 sk_add_bind_node(sk, &l2tp_ip_bind_table);
293 sk_del_node_init(sk);
294 write_unlock_bh(&l2tp_ip_lock);
295
296 ret = 0;
297 sock_reset_flag(sk, SOCK_ZAPPED);
298
299out:
300 release_sock(sk);
301
302 return ret;
303}
304
305static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
306{
307 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
308 int rc;
309
310 if (addr_len < sizeof(*lsa))
311 return -EINVAL;
312
313 if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
314 return -EINVAL;
315
316 lock_sock(sk);
317
318
319 if (sock_flag(sk, SOCK_ZAPPED)) {
320 rc = -EINVAL;
321 goto out_sk;
322 }
323
324 rc = __ip4_datagram_connect(sk, uaddr, addr_len);
325 if (rc < 0)
326 goto out_sk;
327
328 l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
329
330 write_lock_bh(&l2tp_ip_lock);
331 hlist_del_init(&sk->sk_bind_node);
332 sk_add_bind_node(sk, &l2tp_ip_bind_table);
333 write_unlock_bh(&l2tp_ip_lock);
334
335out_sk:
336 release_sock(sk);
337
338 return rc;
339}
340
341static int l2tp_ip_disconnect(struct sock *sk, int flags)
342{
343 if (sock_flag(sk, SOCK_ZAPPED))
344 return 0;
345
346 return __udp_disconnect(sk, flags);
347}
348
349static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
350 int peer)
351{
352 struct sock *sk = sock->sk;
353 struct inet_sock *inet = inet_sk(sk);
354 struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
355 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
356
357 memset(lsa, 0, sizeof(*lsa));
358 lsa->l2tp_family = AF_INET;
359 if (peer) {
360 if (!inet->inet_dport)
361 return -ENOTCONN;
362 lsa->l2tp_conn_id = lsk->peer_conn_id;
363 lsa->l2tp_addr.s_addr = inet->inet_daddr;
364 } else {
365 __be32 addr = inet->inet_rcv_saddr;
366
367 if (!addr)
368 addr = inet->inet_saddr;
369 lsa->l2tp_conn_id = lsk->conn_id;
370 lsa->l2tp_addr.s_addr = addr;
371 }
372 return sizeof(*lsa);
373}
374
375static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
376{
377 int rc;
378
379
380 rc = sock_queue_rcv_skb(sk, skb);
381 if (rc < 0)
382 goto drop;
383
384 return 0;
385
386drop:
387 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
388 kfree_skb(skb);
389 return 0;
390}
391
392
393
394
395static int l2tp_ip_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
396{
397 struct sk_buff *skb;
398 int rc;
399 struct inet_sock *inet = inet_sk(sk);
400 struct rtable *rt = NULL;
401 struct flowi4 *fl4;
402 int connected = 0;
403 __be32 daddr;
404
405 lock_sock(sk);
406
407 rc = -ENOTCONN;
408 if (sock_flag(sk, SOCK_DEAD))
409 goto out;
410
411
412 if (msg->msg_name) {
413 DECLARE_SOCKADDR(struct sockaddr_l2tpip *, lip, msg->msg_name);
414
415 rc = -EINVAL;
416 if (msg->msg_namelen < sizeof(*lip))
417 goto out;
418
419 if (lip->l2tp_family != AF_INET) {
420 rc = -EAFNOSUPPORT;
421 if (lip->l2tp_family != AF_UNSPEC)
422 goto out;
423 }
424
425 daddr = lip->l2tp_addr.s_addr;
426 } else {
427 rc = -EDESTADDRREQ;
428 if (sk->sk_state != TCP_ESTABLISHED)
429 goto out;
430
431 daddr = inet->inet_daddr;
432 connected = 1;
433 }
434
435
436 rc = -ENOMEM;
437 skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
438 4 + len, 0, GFP_KERNEL);
439 if (!skb)
440 goto error;
441
442
443 skb_reserve(skb, 2 + NET_SKB_PAD);
444 skb_reset_network_header(skb);
445 skb_reserve(skb, sizeof(struct iphdr));
446 skb_reset_transport_header(skb);
447
448
449 *((__be32 *)skb_put(skb, 4)) = 0;
450
451
452 rc = memcpy_from_msg(skb_put(skb, len), msg, len);
453 if (rc < 0) {
454 kfree_skb(skb);
455 goto error;
456 }
457
458 fl4 = &inet->cork.fl.u.ip4;
459 if (connected)
460 rt = (struct rtable *)__sk_dst_check(sk, 0);
461
462 rcu_read_lock();
463 if (!rt) {
464 const struct ip_options_rcu *inet_opt;
465
466 inet_opt = rcu_dereference(inet->inet_opt);
467
468
469 if (inet_opt && inet_opt->opt.srr)
470 daddr = inet_opt->opt.faddr;
471
472
473
474
475
476 rt = ip_route_output_ports(sock_net(sk), fl4, sk,
477 daddr, inet->inet_saddr,
478 inet->inet_dport, inet->inet_sport,
479 sk->sk_protocol, RT_CONN_FLAGS(sk),
480 sk->sk_bound_dev_if);
481 if (IS_ERR(rt))
482 goto no_route;
483 if (connected) {
484 sk_setup_caps(sk, &rt->dst);
485 } else {
486 skb_dst_set(skb, &rt->dst);
487 goto xmit;
488 }
489 }
490
491
492
493
494 skb_dst_set_noref(skb, &rt->dst);
495
496xmit:
497
498 rc = ip_queue_xmit(sk, skb, &inet->cork.fl);
499 rcu_read_unlock();
500
501error:
502 if (rc >= 0)
503 rc = len;
504
505out:
506 release_sock(sk);
507 return rc;
508
509no_route:
510 rcu_read_unlock();
511 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
512 kfree_skb(skb);
513 rc = -EHOSTUNREACH;
514 goto out;
515}
516
517static int l2tp_ip_recvmsg(struct sock *sk, struct msghdr *msg,
518 size_t len, int noblock, int flags, int *addr_len)
519{
520 struct inet_sock *inet = inet_sk(sk);
521 size_t copied = 0;
522 int err = -EOPNOTSUPP;
523 DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
524 struct sk_buff *skb;
525
526 if (flags & MSG_OOB)
527 goto out;
528
529 skb = skb_recv_datagram(sk, flags, noblock, &err);
530 if (!skb)
531 goto out;
532
533 copied = skb->len;
534 if (len < copied) {
535 msg->msg_flags |= MSG_TRUNC;
536 copied = len;
537 }
538
539 err = skb_copy_datagram_msg(skb, 0, msg, copied);
540 if (err)
541 goto done;
542
543 sock_recv_timestamp(msg, sk, skb);
544
545
546 if (sin) {
547 sin->sin_family = AF_INET;
548 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
549 sin->sin_port = 0;
550 memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
551 *addr_len = sizeof(*sin);
552 }
553 if (inet->cmsg_flags)
554 ip_cmsg_recv(msg, skb);
555 if (flags & MSG_TRUNC)
556 copied = skb->len;
557done:
558 skb_free_datagram(sk, skb);
559out:
560 return err ? err : copied;
561}
562
563int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg)
564{
565 struct sk_buff *skb;
566 int amount;
567
568 switch (cmd) {
569 case SIOCOUTQ:
570 amount = sk_wmem_alloc_get(sk);
571 break;
572 case SIOCINQ:
573 spin_lock_bh(&sk->sk_receive_queue.lock);
574 skb = skb_peek(&sk->sk_receive_queue);
575 amount = skb ? skb->len : 0;
576 spin_unlock_bh(&sk->sk_receive_queue.lock);
577 break;
578
579 default:
580 return -ENOIOCTLCMD;
581 }
582
583 return put_user(amount, (int __user *)arg);
584}
585EXPORT_SYMBOL_GPL(l2tp_ioctl);
586
587static struct proto l2tp_ip_prot = {
588 .name = "L2TP/IP",
589 .owner = THIS_MODULE,
590 .init = l2tp_ip_open,
591 .close = l2tp_ip_close,
592 .bind = l2tp_ip_bind,
593 .connect = l2tp_ip_connect,
594 .disconnect = l2tp_ip_disconnect,
595 .ioctl = l2tp_ioctl,
596 .destroy = l2tp_ip_destroy_sock,
597 .setsockopt = ip_setsockopt,
598 .getsockopt = ip_getsockopt,
599 .sendmsg = l2tp_ip_sendmsg,
600 .recvmsg = l2tp_ip_recvmsg,
601 .backlog_rcv = l2tp_ip_backlog_recv,
602 .hash = l2tp_ip_hash,
603 .unhash = l2tp_ip_unhash,
604 .obj_size = sizeof(struct l2tp_ip_sock),
605};
606
607static const struct proto_ops l2tp_ip_ops = {
608 .family = PF_INET,
609 .owner = THIS_MODULE,
610 .release = inet_release,
611 .bind = inet_bind,
612 .connect = inet_dgram_connect,
613 .socketpair = sock_no_socketpair,
614 .accept = sock_no_accept,
615 .getname = l2tp_ip_getname,
616 .poll = datagram_poll,
617 .ioctl = inet_ioctl,
618 .gettstamp = sock_gettstamp,
619 .listen = sock_no_listen,
620 .shutdown = inet_shutdown,
621 .setsockopt = sock_common_setsockopt,
622 .getsockopt = sock_common_getsockopt,
623 .sendmsg = inet_sendmsg,
624 .recvmsg = sock_common_recvmsg,
625 .mmap = sock_no_mmap,
626 .sendpage = sock_no_sendpage,
627};
628
629static struct inet_protosw l2tp_ip_protosw = {
630 .type = SOCK_DGRAM,
631 .protocol = IPPROTO_L2TP,
632 .prot = &l2tp_ip_prot,
633 .ops = &l2tp_ip_ops,
634};
635
636static struct net_protocol l2tp_ip_protocol __read_mostly = {
637 .handler = l2tp_ip_recv,
638};
639
640static int __init l2tp_ip_init(void)
641{
642 int err;
643
644 pr_info("L2TP IP encapsulation support (L2TPv3)\n");
645
646 err = proto_register(&l2tp_ip_prot, 1);
647 if (err != 0)
648 goto out;
649
650 err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
651 if (err)
652 goto out1;
653
654 inet_register_protosw(&l2tp_ip_protosw);
655 return 0;
656
657out1:
658 proto_unregister(&l2tp_ip_prot);
659out:
660 return err;
661}
662
663static void __exit l2tp_ip_exit(void)
664{
665 inet_unregister_protosw(&l2tp_ip_protosw);
666 inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
667 proto_unregister(&l2tp_ip_prot);
668}
669
670module_init(l2tp_ip_init);
671module_exit(l2tp_ip_exit);
672
673MODULE_LICENSE("GPL");
674MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
675MODULE_DESCRIPTION("L2TP over IP");
676MODULE_VERSION("1.0");
677
678
679
680
681MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP);
682MODULE_ALIAS_NET_PF_PROTO(PF_INET, IPPROTO_L2TP);
683
