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 #include <linux/icmp.h>
13 #include <linux/module.h>
14 #include <linux/skbuff.h>
15 #include <linux/random.h>
16 #include <linux/socket.h>
17 #include <linux/l2tp.h>
23 #include <net/inet_common.h>
24 #include <net/inet_hashtables.h>
25 #include <net/tcp_states.h>
26 #include <net/protocol.h>
29 #include "l2tp_core.h"
32 /* inet_sock has to be the first member of l2tp_ip_sock */
33 struct inet_sock inet;
46 static DEFINE_RWLOCK(l2tp_ip_lock);
47 static struct hlist_head l2tp_ip_table;
48 static struct hlist_head l2tp_ip_bind_table;
50 static inline struct l2tp_ip_sock *l2tp_ip_sk(const struct sock *sk)
52 return (struct l2tp_ip_sock *)sk;
55 static struct sock *__l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
57 struct hlist_node *node;
60 sk_for_each_bound(sk, node, &l2tp_ip_bind_table) {
61 struct inet_sock *inet = inet_sk(sk);
62 struct l2tp_ip_sock *l2tp = l2tp_ip_sk(sk);
67 if ((l2tp->conn_id == tunnel_id) &&
69 (sk->sk_net == net) &&
71 !(inet->inet_rcv_saddr && inet->inet_rcv_saddr != laddr) &&
72 !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif))
81 static inline struct sock *l2tp_ip_bind_lookup(struct net *net, __be32 laddr, int dif, u32 tunnel_id)
83 struct sock *sk = __l2tp_ip_bind_lookup(net, laddr, dif, tunnel_id);
90 /* When processing receive frames, there are two cases to
91 * consider. Data frames consist of a non-zero session-id and an
92 * optional cookie. Control frames consist of a regular L2TP header
93 * preceded by 32-bits of zeros.
95 * L2TPv3 Session Header Over IP
98 * 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
99 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
101 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
102 * | Cookie (optional, maximum 64 bits)...
103 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
105 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
107 * L2TPv3 Control Message Header Over IP
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 * | (32 bits of zeros) |
113 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
114 * |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length |
115 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
116 * | Control Connection ID |
117 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
119 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
121 * All control frames are passed to userspace.
123 static int l2tp_ip_recv(struct sk_buff *skb)
128 unsigned char *ptr, *optr;
129 struct l2tp_session *session;
130 struct l2tp_tunnel *tunnel = NULL;
134 /* Point to L2TP header */
135 optr = ptr = skb->data;
137 if (!pskb_may_pull(skb, 4))
140 session_id = ntohl(*((__be32 *) ptr));
143 /* RFC3931: L2TP/IP packets have the first 4 bytes containing
144 * the session_id. If it is 0, the packet is a L2TP control
145 * frame and the session_id value can be discarded.
147 if (session_id == 0) {
152 /* Ok, this is a data packet. Lookup the session. */
153 session = l2tp_session_find(&init_net, NULL, session_id);
157 tunnel = session->tunnel;
161 /* Trace packet contents, if enabled */
162 if (tunnel->debug & L2TP_MSG_DATA) {
163 length = min(32u, skb->len);
164 if (!pskb_may_pull(skb, length))
167 printk(KERN_DEBUG "%s: ip recv: ", tunnel->name);
171 printk(" %02X", ptr[offset]);
172 } while (++offset < length);
177 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook);
182 /* Get the tunnel_id from the L2TP header */
183 if (!pskb_may_pull(skb, 12))
186 if ((skb->data[0] & 0xc0) != 0xc0)
189 tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
190 tunnel = l2tp_tunnel_find(&init_net, tunnel_id);
194 struct iphdr *iph = (struct iphdr *) skb_network_header(skb);
196 read_lock_bh(&l2tp_ip_lock);
197 sk = __l2tp_ip_bind_lookup(&init_net, iph->daddr, 0, tunnel_id);
198 read_unlock_bh(&l2tp_ip_lock);
206 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
211 return sk_receive_skb(sk, skb, 1);
221 static int l2tp_ip_open(struct sock *sk)
223 /* Prevent autobind. We don't have ports. */
224 inet_sk(sk)->inet_num = IPPROTO_L2TP;
226 write_lock_bh(&l2tp_ip_lock);
227 sk_add_node(sk, &l2tp_ip_table);
228 write_unlock_bh(&l2tp_ip_lock);
233 static void l2tp_ip_close(struct sock *sk, long timeout)
235 write_lock_bh(&l2tp_ip_lock);
236 hlist_del_init(&sk->sk_bind_node);
237 hlist_del_init(&sk->sk_node);
238 write_unlock_bh(&l2tp_ip_lock);
239 sk_common_release(sk);
242 static void l2tp_ip_destroy_sock(struct sock *sk)
246 while ((skb = __skb_dequeue_tail(&sk->sk_write_queue)) != NULL)
249 sk_refcnt_debug_dec(sk);
252 static int l2tp_ip_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
254 struct inet_sock *inet = inet_sk(sk);
255 struct sockaddr_l2tpip *addr = (struct sockaddr_l2tpip *) uaddr;
260 read_lock_bh(&l2tp_ip_lock);
261 if (__l2tp_ip_bind_lookup(&init_net, addr->l2tp_addr.s_addr, sk->sk_bound_dev_if, addr->l2tp_conn_id))
264 read_unlock_bh(&l2tp_ip_lock);
267 if (sk->sk_state != TCP_CLOSE || addr_len < sizeof(struct sockaddr_l2tpip))
270 chk_addr_ret = inet_addr_type(&init_net, addr->l2tp_addr.s_addr);
271 ret = -EADDRNOTAVAIL;
272 if (addr->l2tp_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
273 chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
276 inet->inet_rcv_saddr = inet->inet_saddr = addr->l2tp_addr.s_addr;
277 if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
278 inet->inet_saddr = 0; /* Use device */
281 l2tp_ip_sk(sk)->conn_id = addr->l2tp_conn_id;
283 write_lock_bh(&l2tp_ip_lock);
284 sk_add_bind_node(sk, &l2tp_ip_bind_table);
285 sk_del_node_init(sk);
286 write_unlock_bh(&l2tp_ip_lock);
294 read_unlock_bh(&l2tp_ip_lock);
299 static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
302 struct inet_sock *inet = inet_sk(sk);
303 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *) uaddr;
309 if (addr_len < sizeof(*lsa))
313 if (lsa->l2tp_family != AF_INET)
318 oif = sk->sk_bound_dev_if;
319 saddr = inet->inet_saddr;
322 if (ipv4_is_multicast(lsa->l2tp_addr.s_addr))
325 rc = ip_route_connect(&rt, lsa->l2tp_addr.s_addr, saddr,
326 RT_CONN_FLAGS(sk), oif,
330 if (rc == -ENETUNREACH)
331 IP_INC_STATS_BH(&init_net, IPSTATS_MIB_OUTNOROUTES);
336 if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
341 l2tp_ip_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
343 if (!inet->inet_saddr)
344 inet->inet_saddr = rt->rt_src;
345 if (!inet->inet_rcv_saddr)
346 inet->inet_rcv_saddr = rt->rt_src;
347 inet->inet_daddr = rt->rt_dst;
348 sk->sk_state = TCP_ESTABLISHED;
349 inet->inet_id = jiffies;
351 sk_dst_set(sk, &rt->dst);
353 write_lock_bh(&l2tp_ip_lock);
354 hlist_del_init(&sk->sk_bind_node);
355 sk_add_bind_node(sk, &l2tp_ip_bind_table);
356 write_unlock_bh(&l2tp_ip_lock);
363 static int l2tp_ip_getname(struct socket *sock, struct sockaddr *uaddr,
364 int *uaddr_len, int peer)
366 struct sock *sk = sock->sk;
367 struct inet_sock *inet = inet_sk(sk);
368 struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
369 struct sockaddr_l2tpip *lsa = (struct sockaddr_l2tpip *)uaddr;
371 memset(lsa, 0, sizeof(*lsa));
372 lsa->l2tp_family = AF_INET;
374 if (!inet->inet_dport)
376 lsa->l2tp_conn_id = lsk->peer_conn_id;
377 lsa->l2tp_addr.s_addr = inet->inet_daddr;
379 __be32 addr = inet->inet_rcv_saddr;
381 addr = inet->inet_saddr;
382 lsa->l2tp_conn_id = lsk->conn_id;
383 lsa->l2tp_addr.s_addr = addr;
385 *uaddr_len = sizeof(*lsa);
389 static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
393 if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
398 /* Charge it to the socket, dropping if the queue is full. */
399 rc = sock_queue_rcv_skb(sk, skb);
406 IP_INC_STATS(&init_net, IPSTATS_MIB_INDISCARDS);
411 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
414 static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, size_t len)
418 struct l2tp_ip_sock *lsa = l2tp_ip_sk(sk);
419 struct inet_sock *inet = inet_sk(sk);
420 struct ip_options *opt = inet->opt;
421 struct rtable *rt = NULL;
425 if (sock_flag(sk, SOCK_DEAD))
428 /* Get and verify the address. */
430 struct sockaddr_l2tpip *lip = (struct sockaddr_l2tpip *) msg->msg_name;
431 if (msg->msg_namelen < sizeof(*lip))
434 if (lip->l2tp_family != AF_INET) {
435 if (lip->l2tp_family != AF_UNSPEC)
436 return -EAFNOSUPPORT;
439 daddr = lip->l2tp_addr.s_addr;
441 if (sk->sk_state != TCP_ESTABLISHED)
442 return -EDESTADDRREQ;
444 daddr = inet->inet_daddr;
448 /* Allocate a socket buffer */
450 skb = sock_wmalloc(sk, 2 + NET_SKB_PAD + sizeof(struct iphdr) +
451 4 + len, 0, GFP_KERNEL);
455 /* Reserve space for headers, putting IP header on 4-byte boundary. */
456 skb_reserve(skb, 2 + NET_SKB_PAD);
457 skb_reset_network_header(skb);
458 skb_reserve(skb, sizeof(struct iphdr));
459 skb_reset_transport_header(skb);
461 /* Insert 0 session_id */
462 *((__be32 *) skb_put(skb, 4)) = 0;
464 /* Copy user data into skb */
465 rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
472 rt = (struct rtable *) __sk_dst_check(sk, 0);
475 /* Use correct destination address if we have options. */
480 struct flowi fl = { .oif = sk->sk_bound_dev_if,
483 .saddr = inet->inet_saddr,
484 .tos = RT_CONN_FLAGS(sk) } },
485 .proto = sk->sk_protocol,
486 .flags = inet_sk_flowi_flags(sk),
487 .uli_u = { .ports = {
488 .sport = inet->inet_sport,
489 .dport = inet->inet_dport } } };
491 /* If this fails, retransmit mechanism of transport layer will
492 * keep trying until route appears or the connection times
495 security_sk_classify_flow(sk, &fl);
496 if (ip_route_output_flow(sock_net(sk), &rt, &fl, sk, 0))
499 sk_setup_caps(sk, &rt->dst);
501 skb_dst_set(skb, dst_clone(&rt->dst));
503 /* Queue the packet to IP for output */
504 rc = ip_queue_xmit(skb);
510 lsa->tx_bytes += len;
519 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
521 return -EHOSTUNREACH;
524 static int l2tp_ip_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
525 size_t len, int noblock, int flags, int *addr_len)
527 struct inet_sock *inet = inet_sk(sk);
528 struct l2tp_ip_sock *lsk = l2tp_ip_sk(sk);
530 int err = -EOPNOTSUPP;
531 struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
538 *addr_len = sizeof(*sin);
540 skb = skb_recv_datagram(sk, flags, noblock, &err);
546 msg->msg_flags |= MSG_TRUNC;
550 err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
554 sock_recv_timestamp(msg, sk, skb);
556 /* Copy the address. */
558 sin->sin_family = AF_INET;
559 sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
561 memset(&sin->sin_zero, 0, sizeof(sin->sin_zero));
563 if (inet->cmsg_flags)
564 ip_cmsg_recv(msg, skb);
565 if (flags & MSG_TRUNC)
568 skb_free_datagram(sk, skb);
576 lsk->rx_bytes += copied;
581 struct proto l2tp_ip_prot = {
583 .owner = THIS_MODULE,
584 .init = l2tp_ip_open,
585 .close = l2tp_ip_close,
586 .bind = l2tp_ip_bind,
587 .connect = l2tp_ip_connect,
588 .disconnect = udp_disconnect,
590 .destroy = l2tp_ip_destroy_sock,
591 .setsockopt = ip_setsockopt,
592 .getsockopt = ip_getsockopt,
593 .sendmsg = l2tp_ip_sendmsg,
594 .recvmsg = l2tp_ip_recvmsg,
595 .backlog_rcv = l2tp_ip_backlog_recv,
597 .unhash = inet_unhash,
598 .obj_size = sizeof(struct l2tp_ip_sock),
600 .compat_setsockopt = compat_ip_setsockopt,
601 .compat_getsockopt = compat_ip_getsockopt,
605 static const struct proto_ops l2tp_ip_ops = {
607 .owner = THIS_MODULE,
608 .release = inet_release,
610 .connect = inet_dgram_connect,
611 .socketpair = sock_no_socketpair,
612 .accept = sock_no_accept,
613 .getname = l2tp_ip_getname,
614 .poll = datagram_poll,
616 .listen = sock_no_listen,
617 .shutdown = inet_shutdown,
618 .setsockopt = sock_common_setsockopt,
619 .getsockopt = sock_common_getsockopt,
620 .sendmsg = inet_sendmsg,
621 .recvmsg = sock_common_recvmsg,
622 .mmap = sock_no_mmap,
623 .sendpage = sock_no_sendpage,
625 .compat_setsockopt = compat_sock_common_setsockopt,
626 .compat_getsockopt = compat_sock_common_getsockopt,
630 static struct inet_protosw l2tp_ip_protosw = {
632 .protocol = IPPROTO_L2TP,
633 .prot = &l2tp_ip_prot,
638 static struct net_protocol l2tp_ip_protocol __read_mostly = {
639 .handler = l2tp_ip_recv,
642 static int __init l2tp_ip_init(void)
646 printk(KERN_INFO "L2TP IP encapsulation support (L2TPv3)\n");
648 err = proto_register(&l2tp_ip_prot, 1);
652 err = inet_add_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
656 inet_register_protosw(&l2tp_ip_protosw);
660 proto_unregister(&l2tp_ip_prot);
665 static void __exit l2tp_ip_exit(void)
667 inet_unregister_protosw(&l2tp_ip_protosw);
668 inet_del_protocol(&l2tp_ip_protocol, IPPROTO_L2TP);
669 proto_unregister(&l2tp_ip_prot);
672 module_init(l2tp_ip_init);
673 module_exit(l2tp_ip_exit);
675 MODULE_LICENSE("GPL");
676 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
677 MODULE_DESCRIPTION("L2TP over IP");
678 MODULE_VERSION("1.0");
679 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, SOCK_DGRAM, IPPROTO_L2TP);