2 * L2TPv3 IP encapsulation support
4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
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.
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
25 #include <net/inet_common.h>
26 #include <net/inet_hashtables.h>
27 #include <net/tcp_states.h>
28 #include <net/protocol.h>
31 #include "l2tp_core.h"
34 /* inet_sock has to be the first member of l2tp_ip_sock */
35 struct inet_sock inet;
41 static DEFINE_RWLOCK(l2tp_ip_lock);
42 static struct hlist_head l2tp_ip_table;
43 static struct hlist_head l2tp_ip_bind_table;
45 static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
47 return (struct l2tp_ip_sock *)sk;
50 static struct sock *__l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
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);
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))
73 static inline struct sock *l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
75 struct sock *sk = __l2tp_ip_bind_lookup(net, laddr, dif, tunnel_id);
82 /* When processing receive frames, there are two cases to
83 * consider. Data frames consist of a non-zero session-id and an
84 * optional cookie. Control frames consist of a regular L2TP header
85 * preceded by 32-bits of zeros.
87 * L2TPv3 Session Header Over IP
90 * 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
91 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
93 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
94 * | Cookie (optional, maximum 64 bits)...
95 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
97 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
99 * L2TPv3 Control Message Header Over IP
102 * 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
103 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
104 * | (32 bits of zeros) |
105 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
106 * |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length |
107 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
108 * | Control Connection ID |
109 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
111 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
113 * All control frames are passed to userspace.
115 static int l2tp_ip_recv(struct sk_buff *skb)
117 struct net *net = dev_net(skb->dev);
121 unsigned char *ptr, *optr;
122 struct l2tp_session *session;
123 struct l2tp_tunnel *tunnel = NULL;
126 /* Point to L2TP header */
127 optr = ptr = skb->data;
129 if (!pskb_may_pull(skb, 4))
132 session_id = ntohl(*((__be32 *) ptr));
135 /* RFC3931: L2TP/IP packets have the first 4 bytes containing
136 * the session_id. If it is 0, the packet is a L2TP control
137 * frame and the session_id value can be discarded.
139 if (session_id == 0) {
144 /* Ok, this is a data packet. Lookup the session. */
145 session = l2tp_session_find(net, NULL, session_id);
149 tunnel = session->tunnel;
153 /* Trace packet contents, if enabled */
154 if (tunnel->debug & L2TP_MSG_DATA) {
155 length = min(32u, skb->len);
156 if (!pskb_may_pull(skb, length))
159 pr_debug("%s: ip recv\n", tunnel->name);
160 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
163 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook);
168 /* Get the tunnel_id from the L2TP header */
169 if (!pskb_may_pull(skb, 12))
172 if ((skb->data[0] & 0xc0) != 0xc0)
175 tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
176 tunnel = l2tp_tunnel_find(net, tunnel_id);
180 struct iphdr *iph = (struct iphdr *) skb_network_header(skb);
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);
192 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
197 return sk_receive_skb(sk, skb, 1);
207 static int l2tp_ip_open(struct sock *sk)
209 /* Prevent autobind. We don't have ports. */
210 inet_sk(sk)->inet_num = IPPROTO_L2TP;
212 write_lock_bh(&l2tp_ip_lock);
213 sk_add_node(sk, &l2tp_ip_table);
214 write_unlock_bh(&l2tp_ip_lock);
219 static void l2tp_ip_close(struct sock *sk, long timeout)
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);
228 static void l2tp_ip_destroy_sock(struct sock *sk)
231 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
233 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
237 l2tp_tunnel_closeall(tunnel);
241 sk_refcnt_debug_dec(sk);
244 static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
246 struct inet_sock *inet = inet_sk(sk);
247 struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
248 struct net *net = sock_net(sk);
252 if (!sock_flag(sk, SOCK_ZAPPED))
254 if (addr_len < sizeof(struct sockaddr_l2tpip))
256 if (addr->l2tp_family != AF_INET)
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))
265 read_unlock_bh(&l2tp_ip_lock);
268 if (sk->sk_state != TCP_CLOSE || addr_len < sizeof(struct sockaddr_l2tpip))
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)
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; /* Use device */
283 l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
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);
290 sock_reset_flag(sk, SOCK_ZAPPED);
298 read_unlock_bh(&l2tp_ip_lock);
303 static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
305 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
308 if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
311 if (addr_len < sizeof(*lsa))
314 if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
317 rc = ip4_datagram_connect(sk, uaddr, addr_len);
323 l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
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);
334 static int l2tp_ip_disconnect(struct sock *sk, int flags)
336 if (sock_flag(sk, SOCK_ZAPPED))
339 return udp_disconnect(sk, flags);
342 static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
343 int *uaddr_len, int peer)
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;
350 memset(lsa, 0, sizeof(*lsa));
351 lsa->l2tp_family = AF_INET;
353 if (!inet->inet_dport)
355 lsa->l2tp_conn_id = lsk->peer_conn_id;
356 lsa->l2tp_addr.s_addr = inet->inet_daddr;
358 __be32 addr = inet->inet_rcv_saddr;
360 addr = inet->inet_saddr;
361 lsa->l2tp_conn_id = lsk->conn_id;
362 lsa->l2tp_addr.s_addr = addr;
364 *uaddr_len = sizeof(*lsa);
368 static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
372 /* Charge it to the socket, dropping if the queue is full. */
373 rc = sock_queue_rcv_skb(sk, skb);
380 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
385 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
388 static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len)
392 struct inet_sock *inet = inet_sk(sk);
393 struct rtable *rt = NULL;
401 if (sock_flag(sk, SOCK_DEAD))
404 /* Get and verify the address. */
406 DECLARE_SOCKADDR(struct sockaddr_l2tpip *, lip, msg->msg_name);
408 if (msg->msg_namelen < sizeof(*lip))
411 if (lip->l2tp_family != AF_INET) {
413 if (lip->l2tp_family != AF_UNSPEC)
417 daddr = lip->l2tp_addr.s_addr;
420 if (sk->sk_state != TCP_ESTABLISHED)
423 daddr = inet->inet_daddr;
427 /* Allocate a socket buffer */
429 skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
430 4 + len, 0, GFP_KERNEL);
434 /* Reserve space for headers, putting IP header on 4-byte boundary. */
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);
440 /* Insert 0 session_id */
441 *((__be32 *) skb_put(skb, 4)) = 0;
443 /* Copy user data into skb */
444 rc = memcpy_from_msg(skb_put(skb, len), msg, len);
450 fl4 = &inet->cork.fl.u.ip4;
452 rt = (struct rtable *) __sk_dst_check(sk, 0);
456 const struct ip_options_rcu *inet_opt;
458 inet_opt = rcu_dereference(inet->inet_opt);
460 /* Use correct destination address if we have options. */
461 if (inet_opt && inet_opt->opt.srr)
462 daddr = inet_opt->opt.faddr;
464 /* If this fails, retransmit mechanism of transport layer will
465 * keep trying until route appears or the connection times
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);
476 sk_setup_caps(sk, &rt->dst);
478 skb_dst_set(skb, &rt->dst);
483 /* We dont need to clone dst here, it is guaranteed to not disappear.
484 * __dev_xmit_skb() might force a refcount if needed.
486 skb_dst_set_noref(skb, &rt->dst);
489 /* Queue the packet to IP for output */
490 rc = ip_queue_xmit(sk, skb, &inet->cork.fl);
503 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
509 static int l2tp_ip_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
510 size_t len, int noblock, int flags, int *addr_len)
512 struct inet_sock *inet = inet_sk(sk);
514 int err = -EOPNOTSUPP;
515 DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
521 skb = skb_recv_datagram(sk, flags, noblock, &err);
527 msg->msg_flags |= MSG_TRUNC;
531 err = skb_copy_datagram_msg(skb, 0, msg, copied);
535 sock_recv_timestamp(msg, sk, skb);
537 /* Copy the address. */
539 sin->sin_family = AF_INET;
540 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
542 memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
543 *addr_len = sizeof(*sin);
545 if (inet->cmsg_flags)
546 ip_cmsg_recv(msg, skb);
547 if (flags & MSG_TRUNC)
550 skb_free_datagram(sk, skb);
552 return err ? err : copied;
555 static struct proto l2tp_ip_prot = {
557 .owner = THIS_MODULE,
558 .init = l2tp_ip_open,
559 .close = l2tp_ip_close,
560 .bind = l2tp_ip_bind,
561 .connect = l2tp_ip_connect,
562 .disconnect = l2tp_ip_disconnect,
564 .destroy = l2tp_ip_destroy_sock,
565 .setsockopt = ip_setsockopt,
566 .getsockopt = ip_getsockopt,
567 .sendmsg = l2tp_ip_sendmsg,
568 .recvmsg = l2tp_ip_recvmsg,
569 .backlog_rcv = l2tp_ip_backlog_recv,
571 .unhash = inet_unhash,
572 .obj_size = sizeof(struct l2tp_ip_sock),
574 .compat_setsockopt = compat_ip_setsockopt,
575 .compat_getsockopt = compat_ip_getsockopt,
579 static const struct proto_ops l2tp_ip_ops = {
581 .owner = THIS_MODULE,
582 .release = inet_release,
584 .connect = inet_dgram_connect,
585 .socketpair = sock_no_socketpair,
586 .accept = sock_no_accept,
587 .getname = l2tp_ip_getname,
588 .poll = datagram_poll,
590 .listen = sock_no_listen,
591 .shutdown = inet_shutdown,
592 .setsockopt = sock_common_setsockopt,
593 .getsockopt = sock_common_getsockopt,
594 .sendmsg = inet_sendmsg,
595 .recvmsg = sock_common_recvmsg,
596 .mmap = sock_no_mmap,
597 .sendpage = sock_no_sendpage,
599 .compat_setsockopt = compat_sock_common_setsockopt,
600 .compat_getsockopt = compat_sock_common_getsockopt,
604 static struct inet_protosw l2tp_ip_protosw = {
606 .protocol = IPPROTO_L2TP,
607 .prot = &l2tp_ip_prot,
611 static struct net_protocol l2tp_ip_protocol __read_mostly = {
612 .handler = l2tp_ip_recv,
616 static int __init l2tp_ip_init(void)
620 pr_info("L2TP IP encapsulation support (L2TPv3)\n");
622 err = proto_register(&l2tp_ip_prot, 1);
626 err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
630 inet_register_protosw(&l2tp_ip_protosw);
634 proto_unregister(&l2tp_ip_prot);
639 static void __exit l2tp_ip_exit(void)
641 inet_unregister_protosw(&l2tp_ip_protosw);
642 inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
643 proto_unregister(&l2tp_ip_prot);
646 module_init(l2tp_ip_init);
647 module_exit(l2tp_ip_exit);
649 MODULE_LICENSE("GPL");
650 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
651 MODULE_DESCRIPTION("L2TP over IP");
652 MODULE_VERSION("1.0");
654 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
657 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 2, IPPROTO_L2TP);