2 * L2TPv3 IP encapsulation support for IPv6
4 * Copyright (c) 2012 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>
21 #include <linux/in6.h>
26 #include <net/inet_common.h>
27 #include <net/inet_hashtables.h>
28 #include <net/tcp_states.h>
29 #include <net/protocol.h>
32 #include <net/transp_v6.h>
33 #include <net/addrconf.h>
34 #include <net/ip6_route.h>
36 #include "l2tp_core.h"
38 struct l2tp_ip6_sock {
39 /* inet_sock has to be the first member of l2tp_ip6_sock */
40 struct inet_sock inet;
45 /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
47 struct ipv6_pinfo inet6;
50 static DEFINE_RWLOCK(l2tp_ip6_lock);
51 static struct hlist_head l2tp_ip6_table;
52 static struct hlist_head l2tp_ip6_bind_table;
54 static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
56 return (struct l2tp_ip6_sock *)sk;
59 static struct sock *__l2tp_ip6_bind_lookup(struct net *net,
60 struct in6_addr *laddr,
61 int dif, u32 tunnel_id)
65 sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
66 struct in6_addr *addr = inet6_rcv_saddr(sk);
67 struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
72 if ((l2tp->conn_id == tunnel_id) &&
73 net_eq(sock_net(sk), net) &&
74 !(addr && ipv6_addr_equal(addr, laddr)) &&
75 !(sk->sk_bound_dev_if && sk->sk_bound_dev_if != dif))
84 static inline struct sock *l2tp_ip6_bind_lookup(struct net *net,
85 struct in6_addr *laddr,
86 int dif, u32 tunnel_id)
88 struct sock *sk = __l2tp_ip6_bind_lookup(net, laddr, dif, tunnel_id);
95 /* When processing receive frames, there are two cases to
96 * consider. Data frames consist of a non-zero session-id and an
97 * optional cookie. Control frames consist of a regular L2TP header
98 * preceded by 32-bits of zeros.
100 * L2TPv3 Session Header Over IP
103 * 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
104 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
106 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
107 * | Cookie (optional, maximum 64 bits)...
108 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
110 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
112 * L2TPv3 Control Message Header Over IP
115 * 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
116 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
117 * | (32 bits of zeros) |
118 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
119 * |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length |
120 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
121 * | Control Connection ID |
122 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
124 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
126 * All control frames are passed to userspace.
128 static int l2tp_ip6_recv(struct sk_buff *skb)
133 unsigned char *ptr, *optr;
134 struct l2tp_session *session;
135 struct l2tp_tunnel *tunnel = NULL;
138 /* Point to L2TP header */
139 optr = ptr = skb->data;
141 if (!pskb_may_pull(skb, 4))
144 session_id = ntohl(*((__be32 *) ptr));
147 /* RFC3931: L2TP/IP packets have the first 4 bytes containing
148 * the session_id. If it is 0, the packet is a L2TP control
149 * frame and the session_id value can be discarded.
151 if (session_id == 0) {
156 /* Ok, this is a data packet. Lookup the session. */
157 session = l2tp_session_find(&init_net, NULL, session_id);
161 tunnel = session->tunnel;
165 /* Trace packet contents, if enabled */
166 if (tunnel->debug & L2TP_MSG_DATA) {
167 length = min(32u, skb->len);
168 if (!pskb_may_pull(skb, length))
171 pr_debug("%s: ip recv\n", tunnel->name);
172 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
175 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
176 tunnel->recv_payload_hook);
180 /* Get the tunnel_id from the L2TP header */
181 if (!pskb_may_pull(skb, 12))
184 if ((skb->data[0] & 0xc0) != 0xc0)
187 tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
188 tunnel = l2tp_tunnel_find(&init_net, tunnel_id);
192 struct ipv6hdr *iph = ipv6_hdr(skb);
194 read_lock_bh(&l2tp_ip6_lock);
195 sk = __l2tp_ip6_bind_lookup(&init_net, &iph->daddr,
197 read_unlock_bh(&l2tp_ip6_lock);
205 if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
210 return sk_receive_skb(sk, skb, 1);
220 static int l2tp_ip6_open(struct sock *sk)
222 /* Prevent autobind. We don't have ports. */
223 inet_sk(sk)->inet_num = IPPROTO_L2TP;
225 write_lock_bh(&l2tp_ip6_lock);
226 sk_add_node(sk, &l2tp_ip6_table);
227 write_unlock_bh(&l2tp_ip6_lock);
232 static void l2tp_ip6_close(struct sock *sk, long timeout)
234 write_lock_bh(&l2tp_ip6_lock);
235 hlist_del_init(&sk->sk_bind_node);
236 sk_del_node_init(sk);
237 write_unlock_bh(&l2tp_ip6_lock);
239 sk_common_release(sk);
242 static void l2tp_ip6_destroy_sock(struct sock *sk)
244 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
247 ip6_flush_pending_frames(sk);
251 l2tp_tunnel_closeall(tunnel);
255 inet6_destroy_sock(sk);
258 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
260 struct inet_sock *inet = inet_sk(sk);
261 struct ipv6_pinfo *np = inet6_sk(sk);
262 struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
267 if (!sock_flag(sk, SOCK_ZAPPED))
269 if (addr->l2tp_family != AF_INET6)
271 if (addr_len < sizeof(*addr))
274 addr_type = ipv6_addr_type(&addr->l2tp_addr);
276 /* l2tp_ip6 sockets are IPv6 only */
277 if (addr_type == IPV6_ADDR_MAPPED)
278 return -EADDRNOTAVAIL;
280 /* L2TP is point-point, not multicast */
281 if (addr_type & IPV6_ADDR_MULTICAST)
282 return -EADDRNOTAVAIL;
285 read_lock_bh(&l2tp_ip6_lock);
286 if (__l2tp_ip6_bind_lookup(&init_net, &addr->l2tp_addr,
287 sk->sk_bound_dev_if, addr->l2tp_conn_id))
289 read_unlock_bh(&l2tp_ip6_lock);
294 if (sk->sk_state != TCP_CLOSE)
297 /* Check if the address belongs to the host. */
299 if (addr_type != IPV6_ADDR_ANY) {
300 struct net_device *dev = NULL;
302 if (addr_type & IPV6_ADDR_LINKLOCAL) {
303 if (addr_len >= sizeof(struct sockaddr_in6) &&
304 addr->l2tp_scope_id) {
305 /* Override any existing binding, if another
306 * one is supplied by user.
308 sk->sk_bound_dev_if = addr->l2tp_scope_id;
311 /* Binding to link-local address requires an
313 if (!sk->sk_bound_dev_if)
317 dev = dev_get_by_index_rcu(sock_net(sk),
318 sk->sk_bound_dev_if);
323 /* ipv4 addr of the socket is invalid. Only the
324 * unspecified and mapped address have a v4 equivalent.
326 v4addr = LOOPBACK4_IPV6;
327 err = -EADDRNOTAVAIL;
328 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
333 inet->inet_rcv_saddr = inet->inet_saddr = v4addr;
334 np->rcv_saddr = addr->l2tp_addr;
335 np->saddr = addr->l2tp_addr;
337 l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
339 write_lock_bh(&l2tp_ip6_lock);
340 sk_add_bind_node(sk, &l2tp_ip6_bind_table);
341 sk_del_node_init(sk);
342 write_unlock_bh(&l2tp_ip6_lock);
344 sock_reset_flag(sk, SOCK_ZAPPED);
355 read_unlock_bh(&l2tp_ip6_lock);
359 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
362 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
363 struct sockaddr_in6 *usin = (struct sockaddr_in6 *) uaddr;
364 struct in6_addr *daddr;
368 if (sock_flag(sk, SOCK_ZAPPED)) /* Must bind first - autobinding does not work */
371 if (addr_len < sizeof(*lsa))
374 addr_type = ipv6_addr_type(&usin->sin6_addr);
375 if (addr_type & IPV6_ADDR_MULTICAST)
378 if (addr_type & IPV6_ADDR_MAPPED) {
379 daddr = &usin->sin6_addr;
380 if (ipv4_is_multicast(daddr->s6_addr32[3]))
384 rc = ip6_datagram_connect(sk, uaddr, addr_len);
388 l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
390 write_lock_bh(&l2tp_ip6_lock);
391 hlist_del_init(&sk->sk_bind_node);
392 sk_add_bind_node(sk, &l2tp_ip6_bind_table);
393 write_unlock_bh(&l2tp_ip6_lock);
400 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
402 if (sock_flag(sk, SOCK_ZAPPED))
405 return udp_disconnect(sk, flags);
408 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
409 int *uaddr_len, int peer)
411 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
412 struct sock *sk = sock->sk;
413 struct ipv6_pinfo *np = inet6_sk(sk);
414 struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
416 lsa->l2tp_family = AF_INET6;
417 lsa->l2tp_flowinfo = 0;
418 lsa->l2tp_scope_id = 0;
419 lsa->l2tp_unused = 0;
421 if (!lsk->peer_conn_id)
423 lsa->l2tp_conn_id = lsk->peer_conn_id;
424 lsa->l2tp_addr = np->daddr;
426 lsa->l2tp_flowinfo = np->flow_label;
428 if (ipv6_addr_any(&np->rcv_saddr))
429 lsa->l2tp_addr = np->saddr;
431 lsa->l2tp_addr = np->rcv_saddr;
433 lsa->l2tp_conn_id = lsk->conn_id;
435 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
436 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
437 *uaddr_len = sizeof(*lsa);
441 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
445 /* Charge it to the socket, dropping if the queue is full. */
446 rc = sock_queue_rcv_skb(sk, skb);
453 IP_INC_STATS(&init_net, IPSTATS_MIB_INDISCARDS);
458 static int l2tp_ip6_push_pending_frames(struct sock *sk)
461 __be32 *transhdr = NULL;
464 skb = skb_peek(&sk->sk_write_queue);
468 transhdr = (__be32 *)skb_transport_header(skb);
471 err = ip6_push_pending_frames(sk);
477 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
480 static int l2tp_ip6_sendmsg(struct kiocb *iocb, struct sock *sk,
481 struct msghdr *msg, size_t len)
483 struct ipv6_txoptions opt_space;
484 struct sockaddr_l2tpip6 *lsa =
485 (struct sockaddr_l2tpip6 *) msg->msg_name;
486 struct in6_addr *daddr, *final_p, final;
487 struct ipv6_pinfo *np = inet6_sk(sk);
488 struct ipv6_txoptions *opt = NULL;
489 struct ip6_flowlabel *flowlabel = NULL;
490 struct dst_entry *dst = NULL;
492 int addr_len = msg->msg_namelen;
496 int transhdrlen = 4; /* zero session-id */
497 int ulen = len + transhdrlen;
500 /* Rough check on arithmetic overflow,
501 better check is made in ip6_append_data().
506 /* Mirror BSD error message compatibility */
507 if (msg->msg_flags & MSG_OOB)
511 * Get and verify the address.
513 memset(&fl6, 0, sizeof(fl6));
515 fl6.flowi6_mark = sk->sk_mark;
518 if (addr_len < SIN6_LEN_RFC2133)
521 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
522 return -EAFNOSUPPORT;
524 daddr = &lsa->l2tp_addr;
526 fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
527 if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
528 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
529 if (flowlabel == NULL)
531 daddr = &flowlabel->dst;
536 * Otherwise it will be difficult to maintain
539 if (sk->sk_state == TCP_ESTABLISHED &&
540 ipv6_addr_equal(daddr, &np->daddr))
543 if (addr_len >= sizeof(struct sockaddr_in6) &&
544 lsa->l2tp_scope_id &&
545 ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
546 fl6.flowi6_oif = lsa->l2tp_scope_id;
548 if (sk->sk_state != TCP_ESTABLISHED)
549 return -EDESTADDRREQ;
552 fl6.flowlabel = np->flow_label;
555 if (fl6.flowi6_oif == 0)
556 fl6.flowi6_oif = sk->sk_bound_dev_if;
558 if (msg->msg_controllen) {
560 memset(opt, 0, sizeof(struct ipv6_txoptions));
561 opt->tot_len = sizeof(struct ipv6_txoptions);
563 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, opt,
564 &hlimit, &tclass, &dontfrag);
566 fl6_sock_release(flowlabel);
569 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
570 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
571 if (flowlabel == NULL)
574 if (!(opt->opt_nflen|opt->opt_flen))
581 opt = fl6_merge_options(&opt_space, flowlabel, opt);
582 opt = ipv6_fixup_options(&opt_space, opt);
584 fl6.flowi6_proto = sk->sk_protocol;
585 if (!ipv6_addr_any(daddr))
588 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
589 if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
590 fl6.saddr = np->saddr;
592 final_p = fl6_update_dst(&fl6, opt, &final);
594 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
595 fl6.flowi6_oif = np->mcast_oif;
596 else if (!fl6.flowi6_oif)
597 fl6.flowi6_oif = np->ucast_oif;
599 security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
601 dst = ip6_dst_lookup_flow(sk, &fl6, final_p, true);
608 if (ipv6_addr_is_multicast(&fl6.daddr))
609 hlimit = np->mcast_hops;
611 hlimit = np->hop_limit;
613 hlimit = ip6_dst_hoplimit(dst);
620 dontfrag = np->dontfrag;
622 if (msg->msg_flags & MSG_CONFIRM)
627 err = ip6_append_data(sk, ip_generic_getfrag, msg->msg_iov,
628 ulen, transhdrlen, hlimit, tclass, opt,
629 &fl6, (struct rt6_info *)dst,
630 msg->msg_flags, dontfrag);
632 ip6_flush_pending_frames(sk);
633 else if (!(msg->msg_flags & MSG_MORE))
634 err = l2tp_ip6_push_pending_frames(sk);
639 fl6_sock_release(flowlabel);
641 return err < 0 ? err : len;
645 if (!(msg->msg_flags & MSG_PROBE) || len)
646 goto back_from_confirm;
651 static int l2tp_ip6_recvmsg(struct kiocb *iocb, struct sock *sk,
652 struct msghdr *msg, size_t len, int noblock,
653 int flags, int *addr_len)
655 struct ipv6_pinfo *np = inet6_sk(sk);
656 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)msg->msg_name;
658 int err = -EOPNOTSUPP;
665 *addr_len = sizeof(*lsa);
667 if (flags & MSG_ERRQUEUE)
668 return ipv6_recv_error(sk, msg, len);
670 skb = skb_recv_datagram(sk, flags, noblock, &err);
676 msg->msg_flags |= MSG_TRUNC;
680 err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
684 sock_recv_timestamp(msg, sk, skb);
686 /* Copy the address. */
688 lsa->l2tp_family = AF_INET6;
689 lsa->l2tp_unused = 0;
690 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
691 lsa->l2tp_flowinfo = 0;
692 lsa->l2tp_scope_id = 0;
693 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
694 lsa->l2tp_scope_id = IP6CB(skb)->iif;
698 ip6_datagram_recv_ctl(sk, msg, skb);
700 if (flags & MSG_TRUNC)
703 skb_free_datagram(sk, skb);
705 return err ? err : copied;
708 static struct proto l2tp_ip6_prot = {
710 .owner = THIS_MODULE,
711 .init = l2tp_ip6_open,
712 .close = l2tp_ip6_close,
713 .bind = l2tp_ip6_bind,
714 .connect = l2tp_ip6_connect,
715 .disconnect = l2tp_ip6_disconnect,
717 .destroy = l2tp_ip6_destroy_sock,
718 .setsockopt = ipv6_setsockopt,
719 .getsockopt = ipv6_getsockopt,
720 .sendmsg = l2tp_ip6_sendmsg,
721 .recvmsg = l2tp_ip6_recvmsg,
722 .backlog_rcv = l2tp_ip6_backlog_recv,
724 .unhash = inet_unhash,
725 .obj_size = sizeof(struct l2tp_ip6_sock),
727 .compat_setsockopt = compat_ipv6_setsockopt,
728 .compat_getsockopt = compat_ipv6_getsockopt,
732 static const struct proto_ops l2tp_ip6_ops = {
734 .owner = THIS_MODULE,
735 .release = inet6_release,
737 .connect = inet_dgram_connect,
738 .socketpair = sock_no_socketpair,
739 .accept = sock_no_accept,
740 .getname = l2tp_ip6_getname,
741 .poll = datagram_poll,
742 .ioctl = inet6_ioctl,
743 .listen = sock_no_listen,
744 .shutdown = inet_shutdown,
745 .setsockopt = sock_common_setsockopt,
746 .getsockopt = sock_common_getsockopt,
747 .sendmsg = inet_sendmsg,
748 .recvmsg = sock_common_recvmsg,
749 .mmap = sock_no_mmap,
750 .sendpage = sock_no_sendpage,
752 .compat_setsockopt = compat_sock_common_setsockopt,
753 .compat_getsockopt = compat_sock_common_getsockopt,
757 static struct inet_protosw l2tp_ip6_protosw = {
759 .protocol = IPPROTO_L2TP,
760 .prot = &l2tp_ip6_prot,
761 .ops = &l2tp_ip6_ops,
765 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
766 .handler = l2tp_ip6_recv,
769 static int __init l2tp_ip6_init(void)
773 pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
775 err = proto_register(&l2tp_ip6_prot, 1);
779 err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
783 inet6_register_protosw(&l2tp_ip6_protosw);
787 proto_unregister(&l2tp_ip6_prot);
792 static void __exit l2tp_ip6_exit(void)
794 inet6_unregister_protosw(&l2tp_ip6_protosw);
795 inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
796 proto_unregister(&l2tp_ip6_prot);
799 module_init(l2tp_ip6_init);
800 module_exit(l2tp_ip6_exit);
802 MODULE_LICENSE("GPL");
803 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
804 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
805 MODULE_VERSION("1.0");
807 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
810 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);