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/inet6_hashtables.h>
29 #include <net/tcp_states.h>
30 #include <net/protocol.h>
33 #include <net/transp_v6.h>
34 #include <net/addrconf.h>
35 #include <net/ip6_route.h>
37 #include "l2tp_core.h"
39 struct l2tp_ip6_sock {
40 /* inet_sock has to be the first member of l2tp_ip6_sock */
41 struct inet_sock inet;
46 /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
48 struct ipv6_pinfo inet6;
51 static DEFINE_RWLOCK(l2tp_ip6_lock);
52 static struct hlist_head l2tp_ip6_table;
53 static struct hlist_head l2tp_ip6_bind_table;
55 static inline struct l2tp_ip6_sock *l2tp_ip6_sk(const struct sock *sk)
57 return (struct l2tp_ip6_sock *)sk;
60 static struct sock *__l2tp_ip6_bind_lookup(const struct net *net,
61 const struct in6_addr *laddr,
62 const struct in6_addr *raddr,
63 int dif, u32 tunnel_id)
67 sk_for_each_bound(sk, &l2tp_ip6_bind_table) {
68 const struct in6_addr *sk_laddr = inet6_rcv_saddr(sk);
69 const struct in6_addr *sk_raddr = &sk->sk_v6_daddr;
70 const struct l2tp_ip6_sock *l2tp = l2tp_ip6_sk(sk);
72 if (!net_eq(sock_net(sk), net))
75 if (sk->sk_bound_dev_if && dif && sk->sk_bound_dev_if != dif)
78 if (sk_laddr && !ipv6_addr_any(sk_laddr) &&
79 !ipv6_addr_any(laddr) && !ipv6_addr_equal(sk_laddr, laddr))
82 if (!ipv6_addr_any(sk_raddr) && raddr &&
83 !ipv6_addr_any(raddr) && !ipv6_addr_equal(sk_raddr, raddr))
86 if (l2tp->conn_id != tunnel_id)
97 /* When processing receive frames, there are two cases to
98 * consider. Data frames consist of a non-zero session-id and an
99 * optional cookie. Control frames consist of a regular L2TP header
100 * preceded by 32-bits of zeros.
102 * L2TPv3 Session Header Over IP
105 * 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
106 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
108 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
109 * | Cookie (optional, maximum 64 bits)...
110 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
112 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
114 * L2TPv3 Control Message Header Over IP
117 * 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
118 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
119 * | (32 bits of zeros) |
120 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
121 * |T|L|x|x|S|x|x|x|x|x|x|x| Ver | Length |
122 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
123 * | Control Connection ID |
124 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
126 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
128 * All control frames are passed to userspace.
130 static int l2tp_ip6_recv(struct sk_buff *skb)
132 struct net *net = dev_net(skb->dev);
136 unsigned char *ptr, *optr;
137 struct l2tp_session *session;
138 struct l2tp_tunnel *tunnel = NULL;
141 if (!pskb_may_pull(skb, 4))
144 /* Point to L2TP header */
145 optr = ptr = skb->data;
146 session_id = ntohl(*((__be32 *) ptr));
149 /* RFC3931: L2TP/IP packets have the first 4 bytes containing
150 * the session_id. If it is 0, the packet is a L2TP control
151 * frame and the session_id value can be discarded.
153 if (session_id == 0) {
158 /* Ok, this is a data packet. Lookup the session. */
159 session = l2tp_session_get(net, NULL, session_id);
163 tunnel = session->tunnel;
167 /* Trace packet contents, if enabled */
168 if (tunnel->debug & L2TP_MSG_DATA) {
169 length = min(32u, skb->len);
170 if (!pskb_may_pull(skb, length))
173 /* Point to L2TP header */
174 optr = ptr = skb->data;
176 pr_debug("%s: ip recv\n", tunnel->name);
177 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
180 l2tp_recv_common(session, skb, ptr, optr, 0, skb->len,
181 tunnel->recv_payload_hook);
182 l2tp_session_dec_refcount(session);
187 /* Get the tunnel_id from the L2TP header */
188 if (!pskb_may_pull(skb, 12))
191 if ((skb->data[0] & 0xc0) != 0xc0)
194 tunnel_id = ntohl(*(__be32 *) &skb->data[4]);
195 tunnel = l2tp_tunnel_find(net, tunnel_id);
200 struct ipv6hdr *iph = ipv6_hdr(skb);
202 read_lock_bh(&l2tp_ip6_lock);
203 sk = __l2tp_ip6_bind_lookup(net, &iph->daddr, &iph->saddr,
204 inet6_iif(skb), tunnel_id);
206 read_unlock_bh(&l2tp_ip6_lock);
211 read_unlock_bh(&l2tp_ip6_lock);
214 if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
219 return sk_receive_skb(sk, skb, 1);
222 l2tp_session_dec_refcount(session);
233 static int l2tp_ip6_open(struct sock *sk)
235 /* Prevent autobind. We don't have ports. */
236 inet_sk(sk)->inet_num = IPPROTO_L2TP;
238 write_lock_bh(&l2tp_ip6_lock);
239 sk_add_node(sk, &l2tp_ip6_table);
240 write_unlock_bh(&l2tp_ip6_lock);
245 static void l2tp_ip6_close(struct sock *sk, long timeout)
247 write_lock_bh(&l2tp_ip6_lock);
248 hlist_del_init(&sk->sk_bind_node);
249 sk_del_node_init(sk);
250 write_unlock_bh(&l2tp_ip6_lock);
252 sk_common_release(sk);
255 static void l2tp_ip6_destroy_sock(struct sock *sk)
257 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk);
260 ip6_flush_pending_frames(sk);
264 l2tp_tunnel_closeall(tunnel);
268 inet6_destroy_sock(sk);
271 static int l2tp_ip6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
273 struct inet_sock *inet = inet_sk(sk);
274 struct ipv6_pinfo *np = inet6_sk(sk);
275 struct sockaddr_l2tpip6 *addr = (struct sockaddr_l2tpip6 *) uaddr;
276 struct net *net = sock_net(sk);
282 if (addr->l2tp_family != AF_INET6)
284 if (addr_len < sizeof(*addr))
287 addr_type = ipv6_addr_type(&addr->l2tp_addr);
289 /* l2tp_ip6 sockets are IPv6 only */
290 if (addr_type == IPV6_ADDR_MAPPED)
291 return -EADDRNOTAVAIL;
293 /* L2TP is point-point, not multicast */
294 if (addr_type & IPV6_ADDR_MULTICAST)
295 return -EADDRNOTAVAIL;
300 if (!sock_flag(sk, SOCK_ZAPPED))
303 if (sk->sk_state != TCP_CLOSE)
306 bound_dev_if = sk->sk_bound_dev_if;
308 /* Check if the address belongs to the host. */
310 if (addr_type != IPV6_ADDR_ANY) {
311 struct net_device *dev = NULL;
313 if (addr_type & IPV6_ADDR_LINKLOCAL) {
314 if (addr->l2tp_scope_id)
315 bound_dev_if = addr->l2tp_scope_id;
317 /* Binding to link-local address requires an
324 dev = dev_get_by_index_rcu(sock_net(sk), bound_dev_if);
329 /* ipv4 addr of the socket is invalid. Only the
330 * unspecified and mapped address have a v4 equivalent.
332 v4addr = LOOPBACK4_IPV6;
333 err = -EADDRNOTAVAIL;
334 if (!ipv6_chk_addr(sock_net(sk), &addr->l2tp_addr, dev, 0))
339 write_lock_bh(&l2tp_ip6_lock);
340 if (__l2tp_ip6_bind_lookup(net, &addr->l2tp_addr, NULL, bound_dev_if,
341 addr->l2tp_conn_id)) {
342 write_unlock_bh(&l2tp_ip6_lock);
347 inet->inet_saddr = v4addr;
348 inet->inet_rcv_saddr = v4addr;
349 sk->sk_bound_dev_if = bound_dev_if;
350 sk->sk_v6_rcv_saddr = addr->l2tp_addr;
351 np->saddr = addr->l2tp_addr;
353 l2tp_ip6_sk(sk)->conn_id = addr->l2tp_conn_id;
355 sk_add_bind_node(sk, &l2tp_ip6_bind_table);
356 sk_del_node_init(sk);
357 write_unlock_bh(&l2tp_ip6_lock);
359 sock_reset_flag(sk, SOCK_ZAPPED);
371 static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
374 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *) uaddr;
375 struct sockaddr_in6 *usin = (struct sockaddr_in6 *) uaddr;
376 struct in6_addr *daddr;
380 if (addr_len < sizeof(*lsa))
383 if (usin->sin6_family != AF_INET6)
386 addr_type = ipv6_addr_type(&usin->sin6_addr);
387 if (addr_type & IPV6_ADDR_MULTICAST)
390 if (addr_type & IPV6_ADDR_MAPPED) {
391 daddr = &usin->sin6_addr;
392 if (ipv4_is_multicast(daddr->s6_addr32[3]))
398 /* Must bind first - autobinding does not work */
399 if (sock_flag(sk, SOCK_ZAPPED)) {
404 rc = __ip6_datagram_connect(sk, uaddr, addr_len);
408 l2tp_ip6_sk(sk)->peer_conn_id = lsa->l2tp_conn_id;
410 write_lock_bh(&l2tp_ip6_lock);
411 hlist_del_init(&sk->sk_bind_node);
412 sk_add_bind_node(sk, &l2tp_ip6_bind_table);
413 write_unlock_bh(&l2tp_ip6_lock);
421 static int l2tp_ip6_disconnect(struct sock *sk, int flags)
423 if (sock_flag(sk, SOCK_ZAPPED))
426 return __udp_disconnect(sk, flags);
429 static int l2tp_ip6_getname(struct socket *sock, struct sockaddr *uaddr,
430 int *uaddr_len, int peer)
432 struct sockaddr_l2tpip6 *lsa = (struct sockaddr_l2tpip6 *)uaddr;
433 struct sock *sk = sock->sk;
434 struct ipv6_pinfo *np = inet6_sk(sk);
435 struct l2tp_ip6_sock *lsk = l2tp_ip6_sk(sk);
437 lsa->l2tp_family = AF_INET6;
438 lsa->l2tp_flowinfo = 0;
439 lsa->l2tp_scope_id = 0;
440 lsa->l2tp_unused = 0;
442 if (!lsk->peer_conn_id)
444 lsa->l2tp_conn_id = lsk->peer_conn_id;
445 lsa->l2tp_addr = sk->sk_v6_daddr;
447 lsa->l2tp_flowinfo = np->flow_label;
449 if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))
450 lsa->l2tp_addr = np->saddr;
452 lsa->l2tp_addr = sk->sk_v6_rcv_saddr;
454 lsa->l2tp_conn_id = lsk->conn_id;
456 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
457 lsa->l2tp_scope_id = sk->sk_bound_dev_if;
458 *uaddr_len = sizeof(*lsa);
462 static int l2tp_ip6_backlog_recv(struct sock *sk, struct sk_buff *skb)
466 /* Charge it to the socket, dropping if the queue is full. */
467 rc = sock_queue_rcv_skb(sk, skb);
474 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
479 static int l2tp_ip6_push_pending_frames(struct sock *sk)
482 __be32 *transhdr = NULL;
485 skb = skb_peek(&sk->sk_write_queue);
489 transhdr = (__be32 *)skb_transport_header(skb);
492 err = ip6_push_pending_frames(sk);
498 /* Userspace will call sendmsg() on the tunnel socket to send L2TP
501 static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
503 struct ipv6_txoptions opt_space;
504 DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
505 struct in6_addr *daddr, *final_p, final;
506 struct ipv6_pinfo *np = inet6_sk(sk);
507 struct ipv6_txoptions *opt_to_free = NULL;
508 struct ipv6_txoptions *opt = NULL;
509 struct ip6_flowlabel *flowlabel = NULL;
510 struct dst_entry *dst = NULL;
512 struct sockcm_cookie sockc_unused = {0};
513 struct ipcm6_cookie ipc6;
514 int addr_len = msg->msg_namelen;
515 int transhdrlen = 4; /* zero session-id */
516 int ulen = len + transhdrlen;
519 /* Rough check on arithmetic overflow,
520 better check is made in ip6_append_data().
525 /* Mirror BSD error message compatibility */
526 if (msg->msg_flags & MSG_OOB)
530 * Get and verify the address.
532 memset(&fl6, 0, sizeof(fl6));
534 fl6.flowi6_mark = sk->sk_mark;
535 fl6.flowi6_uid = sk->sk_uid;
542 if (addr_len < SIN6_LEN_RFC2133)
545 if (lsa->l2tp_family && lsa->l2tp_family != AF_INET6)
546 return -EAFNOSUPPORT;
548 daddr = &lsa->l2tp_addr;
550 fl6.flowlabel = lsa->l2tp_flowinfo & IPV6_FLOWINFO_MASK;
551 if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
552 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
553 if (flowlabel == NULL)
559 * Otherwise it will be difficult to maintain
562 if (sk->sk_state == TCP_ESTABLISHED &&
563 ipv6_addr_equal(daddr, &sk->sk_v6_daddr))
564 daddr = &sk->sk_v6_daddr;
566 if (addr_len >= sizeof(struct sockaddr_in6) &&
567 lsa->l2tp_scope_id &&
568 ipv6_addr_type(daddr) & IPV6_ADDR_LINKLOCAL)
569 fl6.flowi6_oif = lsa->l2tp_scope_id;
571 if (sk->sk_state != TCP_ESTABLISHED)
572 return -EDESTADDRREQ;
574 daddr = &sk->sk_v6_daddr;
575 fl6.flowlabel = np->flow_label;
578 if (fl6.flowi6_oif == 0)
579 fl6.flowi6_oif = sk->sk_bound_dev_if;
581 if (msg->msg_controllen) {
583 memset(opt, 0, sizeof(struct ipv6_txoptions));
584 opt->tot_len = sizeof(struct ipv6_txoptions);
587 err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, &fl6, &ipc6,
590 fl6_sock_release(flowlabel);
593 if ((fl6.flowlabel & IPV6_FLOWLABEL_MASK) && !flowlabel) {
594 flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
595 if (flowlabel == NULL)
598 if (!(opt->opt_nflen|opt->opt_flen))
607 opt = fl6_merge_options(&opt_space, flowlabel, opt);
608 opt = ipv6_fixup_options(&opt_space, opt);
611 fl6.flowi6_proto = sk->sk_protocol;
612 if (!ipv6_addr_any(daddr))
615 fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
616 if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
617 fl6.saddr = np->saddr;
619 final_p = fl6_update_dst(&fl6, opt, &final);
621 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
622 fl6.flowi6_oif = np->mcast_oif;
623 else if (!fl6.flowi6_oif)
624 fl6.flowi6_oif = np->ucast_oif;
626 security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
629 ipc6.tclass = np->tclass;
631 fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
633 dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
640 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
642 if (ipc6.dontfrag < 0)
643 ipc6.dontfrag = np->dontfrag;
645 if (msg->msg_flags & MSG_CONFIRM)
650 err = ip6_append_data(sk, ip_generic_getfrag, msg,
651 ulen, transhdrlen, &ipc6,
652 &fl6, (struct rt6_info *)dst,
653 msg->msg_flags, &sockc_unused);
655 ip6_flush_pending_frames(sk);
656 else if (!(msg->msg_flags & MSG_MORE))
657 err = l2tp_ip6_push_pending_frames(sk);
662 fl6_sock_release(flowlabel);
663 txopt_put(opt_to_free);
665 return err < 0 ? err : len;
668 if (msg->msg_flags & MSG_PROBE)
669 dst_confirm_neigh(dst, &fl6.daddr);
670 if (!(msg->msg_flags & MSG_PROBE) || len)
671 goto back_from_confirm;
676 static int l2tp_ip6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
677 int noblock, int flags, int *addr_len)
679 struct ipv6_pinfo *np = inet6_sk(sk);
680 DECLARE_SOCKADDR(struct sockaddr_l2tpip6 *, lsa, msg->msg_name);
682 int err = -EOPNOTSUPP;
689 *addr_len = sizeof(*lsa);
691 if (flags & MSG_ERRQUEUE)
692 return ipv6_recv_error(sk, msg, len, addr_len);
694 skb = skb_recv_datagram(sk, flags, noblock, &err);
700 msg->msg_flags |= MSG_TRUNC;
704 err = skb_copy_datagram_msg(skb, 0, msg, copied);
708 sock_recv_timestamp(msg, sk, skb);
710 /* Copy the address. */
712 lsa->l2tp_family = AF_INET6;
713 lsa->l2tp_unused = 0;
714 lsa->l2tp_addr = ipv6_hdr(skb)->saddr;
715 lsa->l2tp_flowinfo = 0;
716 lsa->l2tp_scope_id = 0;
717 lsa->l2tp_conn_id = 0;
718 if (ipv6_addr_type(&lsa->l2tp_addr) & IPV6_ADDR_LINKLOCAL)
719 lsa->l2tp_scope_id = inet6_iif(skb);
723 ip6_datagram_recv_ctl(sk, msg, skb);
725 if (flags & MSG_TRUNC)
728 skb_free_datagram(sk, skb);
730 return err ? err : copied;
733 static struct proto l2tp_ip6_prot = {
735 .owner = THIS_MODULE,
736 .init = l2tp_ip6_open,
737 .close = l2tp_ip6_close,
738 .bind = l2tp_ip6_bind,
739 .connect = l2tp_ip6_connect,
740 .disconnect = l2tp_ip6_disconnect,
742 .destroy = l2tp_ip6_destroy_sock,
743 .setsockopt = ipv6_setsockopt,
744 .getsockopt = ipv6_getsockopt,
745 .sendmsg = l2tp_ip6_sendmsg,
746 .recvmsg = l2tp_ip6_recvmsg,
747 .backlog_rcv = l2tp_ip6_backlog_recv,
749 .unhash = inet_unhash,
750 .obj_size = sizeof(struct l2tp_ip6_sock),
752 .compat_setsockopt = compat_ipv6_setsockopt,
753 .compat_getsockopt = compat_ipv6_getsockopt,
757 static const struct proto_ops l2tp_ip6_ops = {
759 .owner = THIS_MODULE,
760 .release = inet6_release,
762 .connect = inet_dgram_connect,
763 .socketpair = sock_no_socketpair,
764 .accept = sock_no_accept,
765 .getname = l2tp_ip6_getname,
766 .poll = datagram_poll,
767 .ioctl = inet6_ioctl,
768 .listen = sock_no_listen,
769 .shutdown = inet_shutdown,
770 .setsockopt = sock_common_setsockopt,
771 .getsockopt = sock_common_getsockopt,
772 .sendmsg = inet_sendmsg,
773 .recvmsg = sock_common_recvmsg,
774 .mmap = sock_no_mmap,
775 .sendpage = sock_no_sendpage,
777 .compat_setsockopt = compat_sock_common_setsockopt,
778 .compat_getsockopt = compat_sock_common_getsockopt,
782 static struct inet_protosw l2tp_ip6_protosw = {
784 .protocol = IPPROTO_L2TP,
785 .prot = &l2tp_ip6_prot,
786 .ops = &l2tp_ip6_ops,
789 static struct inet6_protocol l2tp_ip6_protocol __read_mostly = {
790 .handler = l2tp_ip6_recv,
793 static int __init l2tp_ip6_init(void)
797 pr_info("L2TP IP encapsulation support for IPv6 (L2TPv3)\n");
799 err = proto_register(&l2tp_ip6_prot, 1);
803 err = inet6_add_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
807 inet6_register_protosw(&l2tp_ip6_protosw);
811 proto_unregister(&l2tp_ip6_prot);
816 static void __exit l2tp_ip6_exit(void)
818 inet6_unregister_protosw(&l2tp_ip6_protosw);
819 inet6_del_protocol(&l2tp_ip6_protocol, IPPROTO_L2TP);
820 proto_unregister(&l2tp_ip6_prot);
823 module_init(l2tp_ip6_init);
824 module_exit(l2tp_ip6_exit);
826 MODULE_LICENSE("GPL");
827 MODULE_AUTHOR("Chris Elston <celston@katalix.com>");
828 MODULE_DESCRIPTION("L2TP IP encapsulation for IPv6");
829 MODULE_VERSION("1.0");
831 /* Use the value of SOCK_DGRAM (2) directory, because __stringify doesn't like
834 MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 2, IPPROTO_L2TP);
835 MODULE_ALIAS_NET_PF_PROTO(PF_INET6, IPPROTO_L2TP);