diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index ba06c1c..f8444f4 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -160,7 +160,7 @@ obj-$(CONFIG_PPP_DEFLATE) += ppp_deflate.o
 obj-$(CONFIG_PPP_BSDCOMP) += bsd_comp.o
 obj-$(CONFIG_PPP_MPPE) += ppp_mppe.o
 obj-$(CONFIG_PPPOE) += pppox.o pppoe.o
-obj-$(CONFIG_PPPOL2TP) += pppox.o pppol2tp.o
+obj-$(CONFIG_PPPOL2TP) += pppox.o
 
 obj-$(CONFIG_SLIP) += slip.o
 obj-$(CONFIG_SLHC) += slhc.o
diff --git a/drivers/net/pppol2tp.c b/drivers/net/pppol2tp.c
deleted file mode 100644
index 449a982..0000000
--- a/drivers/net/pppol2tp.c
+++ /dev/null
@@ -1,2680 +0,0 @@
-/*****************************************************************************
- * Linux PPP over L2TP (PPPoX/PPPoL2TP) Sockets
- *
- * PPPoX    --- Generic PPP encapsulation socket family
- * PPPoL2TP --- PPP over L2TP (RFC 2661)
- *
- * Version:	1.0.0
- *
- * Authors:	Martijn van Oosterhout <kleptog@svana.org>
- *		James Chapman (jchapman@katalix.com)
- * Contributors:
- *		Michal Ostrowski <mostrows@speakeasy.net>
- *		Arnaldo Carvalho de Melo <acme@xconectiva.com.br>
- *		David S. Miller (davem@redhat.com)
- *
- * License:
- *		This program is free software; you can redistribute it and/or
- *		modify it under the terms of the GNU General Public License
- *		as published by the Free Software Foundation; either version
- *		2 of the License, or (at your option) any later version.
- *
- */
-
-/* This driver handles only L2TP data frames; control frames are handled by a
- * userspace application.
- *
- * To send data in an L2TP session, userspace opens a PPPoL2TP socket and
- * attaches it to a bound UDP socket with local tunnel_id / session_id and
- * peer tunnel_id / session_id set. Data can then be sent or received using
- * regular socket sendmsg() / recvmsg() calls. Kernel parameters of the socket
- * can be read or modified using ioctl() or [gs]etsockopt() calls.
- *
- * When a PPPoL2TP socket is connected with local and peer session_id values
- * zero, the socket is treated as a special tunnel management socket.
- *
- * Here's example userspace code to create a socket for sending/receiving data
- * over an L2TP session:-
- *
- *	struct sockaddr_pppol2tp sax;
- *	int fd;
- *	int session_fd;
- *
- *	fd = socket(AF_PPPOX, SOCK_DGRAM, PX_PROTO_OL2TP);
- *
- *	sax.sa_family = AF_PPPOX;
- *	sax.sa_protocol = PX_PROTO_OL2TP;
- *	sax.pppol2tp.fd = tunnel_fd;	// bound UDP socket
- *	sax.pppol2tp.addr.sin_addr.s_addr = addr->sin_addr.s_addr;
- *	sax.pppol2tp.addr.sin_port = addr->sin_port;
- *	sax.pppol2tp.addr.sin_family = AF_INET;
- *	sax.pppol2tp.s_tunnel  = tunnel_id;
- *	sax.pppol2tp.s_session = session_id;
- *	sax.pppol2tp.d_tunnel  = peer_tunnel_id;
- *	sax.pppol2tp.d_session = peer_session_id;
- *
- *	session_fd = connect(fd, (struct sockaddr *)&sax, sizeof(sax));
- *
- * A pppd plugin that allows PPP traffic to be carried over L2TP using
- * this driver is available from the OpenL2TP project at
- * http://openl2tp.sourceforge.net.
- */
-
-#include <linux/module.h>
-#include <linux/string.h>
-#include <linux/list.h>
-#include <asm/uaccess.h>
-
-#include <linux/kernel.h>
-#include <linux/spinlock.h>
-#include <linux/kthread.h>
-#include <linux/sched.h>
-#include <linux/slab.h>
-#include <linux/errno.h>
-#include <linux/jiffies.h>
-
-#include <linux/netdevice.h>
-#include <linux/net.h>
-#include <linux/inetdevice.h>
-#include <linux/skbuff.h>
-#include <linux/init.h>
-#include <linux/ip.h>
-#include <linux/udp.h>
-#include <linux/if_pppox.h>
-#include <linux/if_pppol2tp.h>
-#include <net/sock.h>
-#include <linux/ppp_channel.h>
-#include <linux/ppp_defs.h>
-#include <linux/if_ppp.h>
-#include <linux/file.h>
-#include <linux/hash.h>
-#include <linux/sort.h>
-#include <linux/proc_fs.h>
-#include <linux/nsproxy.h>
-#include <net/net_namespace.h>
-#include <net/netns/generic.h>
-#include <net/dst.h>
-#include <net/ip.h>
-#include <net/udp.h>
-#include <net/xfrm.h>
-
-#include <asm/byteorder.h>
-#include <asm/atomic.h>
-
-
-#define PPPOL2TP_DRV_VERSION	"V1.0"
-
-/* L2TP header constants */
-#define L2TP_HDRFLAG_T	   0x8000
-#define L2TP_HDRFLAG_L	   0x4000
-#define L2TP_HDRFLAG_S	   0x0800
-#define L2TP_HDRFLAG_O	   0x0200
-#define L2TP_HDRFLAG_P	   0x0100
-
-#define L2TP_HDR_VER_MASK  0x000F
-#define L2TP_HDR_VER	   0x0002
-
-/* Space for UDP, L2TP and PPP headers */
-#define PPPOL2TP_HEADER_OVERHEAD	40
-
-/* Just some random numbers */
-#define L2TP_TUNNEL_MAGIC	0x42114DDA
-#define L2TP_SESSION_MAGIC	0x0C04EB7D
-
-#define PPPOL2TP_HASH_BITS	4
-#define PPPOL2TP_HASH_SIZE	(1 << PPPOL2TP_HASH_BITS)
-
-/* Default trace flags */
-#define PPPOL2TP_DEFAULT_DEBUG_FLAGS	0
-
-#define PRINTK(_mask, _type, _lvl, _fmt, args...)			\
-	do {								\
-		if ((_mask) & (_type))					\
-			printk(_lvl "PPPOL2TP: " _fmt, ##args);		\
-	} while(0)
-
-/* Number of bytes to build transmit L2TP headers.
- * Unfortunately the size is different depending on whether sequence numbers
- * are enabled.
- */
-#define PPPOL2TP_L2TP_HDR_SIZE_SEQ		10
-#define PPPOL2TP_L2TP_HDR_SIZE_NOSEQ		6
-
-struct pppol2tp_tunnel;
-
-/* Describes a session. It is the sk_user_data field in the PPPoL2TP
- * socket. Contains information to determine incoming packets and transmit
- * outgoing ones.
- */
-struct pppol2tp_session
-{
-	int			magic;		/* should be
-						 * L2TP_SESSION_MAGIC */
-	int			owner;		/* pid that opened the socket */
-
-	struct sock		*sock;		/* Pointer to the session
-						 * PPPoX socket */
-	struct sock		*tunnel_sock;	/* Pointer to the tunnel UDP
-						 * socket */
-
-	struct pppol2tp_addr	tunnel_addr;	/* Description of tunnel */
-
-	struct pppol2tp_tunnel	*tunnel;	/* back pointer to tunnel
-						 * context */
-
-	char			name[20];	/* "sess xxxxx/yyyyy", where
-						 * x=tunnel_id, y=session_id */
-	int			mtu;
-	int			mru;
-	int			flags;		/* accessed by PPPIOCGFLAGS.
-						 * Unused. */
-	unsigned		recv_seq:1;	/* expect receive packets with
-						 * sequence numbers? */
-	unsigned		send_seq:1;	/* send packets with sequence
-						 * numbers? */
-	unsigned		lns_mode:1;	/* behave as LNS? LAC enables
-						 * sequence numbers under
-						 * control of LNS. */
-	int			debug;		/* bitmask of debug message
-						 * categories */
-	int			reorder_timeout; /* configured reorder timeout
-						  * (in jiffies) */
-	u16			nr;		/* session NR state (receive) */
-	u16			ns;		/* session NR state (send) */
-	struct sk_buff_head	reorder_q;	/* receive reorder queue */
-	struct pppol2tp_ioc_stats stats;
-	struct hlist_node	hlist;		/* Hash list node */
-};
-
-/* The sk_user_data field of the tunnel's UDP socket. It contains info to track
- * all the associated sessions so incoming packets can be sorted out
- */
-struct pppol2tp_tunnel
-{
-	int			magic;		/* Should be L2TP_TUNNEL_MAGIC */
-	rwlock_t		hlist_lock;	/* protect session_hlist */
-	struct hlist_head	session_hlist[PPPOL2TP_HASH_SIZE];
-						/* hashed list of sessions,
-						 * hashed by id */
-	int			debug;		/* bitmask of debug message
-						 * categories */
-	char			name[12];	/* "tunl xxxxx" */
-	struct pppol2tp_ioc_stats stats;
-
-	void (*old_sk_destruct)(struct sock *);
-
-	struct sock		*sock;		/* Parent socket */
-	struct list_head	list;		/* Keep a list of all open
-						 * prepared sockets */
-	struct net		*pppol2tp_net;	/* the net we belong to */
-
-	atomic_t		ref_count;
-};
-
-/* Private data stored for received packets in the skb.
- */
-struct pppol2tp_skb_cb {
-	u16			ns;
-	u16			nr;
-	u16			has_seq;
-	u16			length;
-	unsigned long		expires;
-};
-
-#define PPPOL2TP_SKB_CB(skb)	((struct pppol2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
-
-static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb);
-static void pppol2tp_tunnel_free(struct pppol2tp_tunnel *tunnel);
-
-static atomic_t pppol2tp_tunnel_count;
-static atomic_t pppol2tp_session_count;
-static struct ppp_channel_ops pppol2tp_chan_ops = { pppol2tp_xmit , NULL };
-static const struct proto_ops pppol2tp_ops;
-
-/* per-net private data for this module */
-static int pppol2tp_net_id __read_mostly;
-struct pppol2tp_net {
-	struct list_head pppol2tp_tunnel_list;
-	rwlock_t pppol2tp_tunnel_list_lock;
-};
-
-static inline struct pppol2tp_net *pppol2tp_pernet(struct net *net)
-{
-	BUG_ON(!net);
-
-	return net_generic(net, pppol2tp_net_id);
-}
-
-/* Helpers to obtain tunnel/session contexts from sockets.
- */
-static inline struct pppol2tp_session *pppol2tp_sock_to_session(struct sock *sk)
-{
-	struct pppol2tp_session *session;
-
-	if (sk == NULL)
-		return NULL;
-
-	sock_hold(sk);
-	session = (struct pppol2tp_session *)(sk->sk_user_data);
-	if (session == NULL) {
-		sock_put(sk);
-		goto out;
-	}
-
-	BUG_ON(session->magic != L2TP_SESSION_MAGIC);
-out:
-	return session;
-}
-
-static inline struct pppol2tp_tunnel *pppol2tp_sock_to_tunnel(struct sock *sk)
-{
-	struct pppol2tp_tunnel *tunnel;
-
-	if (sk == NULL)
-		return NULL;
-
-	sock_hold(sk);
-	tunnel = (struct pppol2tp_tunnel *)(sk->sk_user_data);
-	if (tunnel == NULL) {
-		sock_put(sk);
-		goto out;
-	}
-
-	BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
-out:
-	return tunnel;
-}
-
-/* Tunnel reference counts. Incremented per session that is added to
- * the tunnel.
- */
-static inline void pppol2tp_tunnel_inc_refcount(struct pppol2tp_tunnel *tunnel)
-{
-	atomic_inc(&tunnel->ref_count);
-}
-
-static inline void pppol2tp_tunnel_dec_refcount(struct pppol2tp_tunnel *tunnel)
-{
-	if (atomic_dec_and_test(&tunnel->ref_count))
-		pppol2tp_tunnel_free(tunnel);
-}
-
-/* Session hash list.
- * The session_id SHOULD be random according to RFC2661, but several
- * L2TP implementations (Cisco and Microsoft) use incrementing
- * session_ids.  So we do a real hash on the session_id, rather than a
- * simple bitmask.
- */
-static inline struct hlist_head *
-pppol2tp_session_id_hash(struct pppol2tp_tunnel *tunnel, u16 session_id)
-{
-	unsigned long hash_val = (unsigned long) session_id;
-	return &tunnel->session_hlist[hash_long(hash_val, PPPOL2TP_HASH_BITS)];
-}
-
-/* Lookup a session by id
- */
-static struct pppol2tp_session *
-pppol2tp_session_find(struct pppol2tp_tunnel *tunnel, u16 session_id)
-{
-	struct hlist_head *session_list =
-		pppol2tp_session_id_hash(tunnel, session_id);
-	struct pppol2tp_session *session;
-	struct hlist_node *walk;
-
-	read_lock_bh(&tunnel->hlist_lock);
-	hlist_for_each_entry(session, walk, session_list, hlist) {
-		if (session->tunnel_addr.s_session == session_id) {
-			read_unlock_bh(&tunnel->hlist_lock);
-			return session;
-		}
-	}
-	read_unlock_bh(&tunnel->hlist_lock);
-
-	return NULL;
-}
-
-/* Lookup a tunnel by id
- */
-static struct pppol2tp_tunnel *pppol2tp_tunnel_find(struct net *net, u16 tunnel_id)
-{
-	struct pppol2tp_tunnel *tunnel;
-	struct pppol2tp_net *pn = pppol2tp_pernet(net);
-
-	read_lock_bh(&pn->pppol2tp_tunnel_list_lock);
-	list_for_each_entry(tunnel, &pn->pppol2tp_tunnel_list, list) {
-		if (tunnel->stats.tunnel_id == tunnel_id) {
-			read_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
-			return tunnel;
-		}
-	}
-	read_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
-
-	return NULL;
-}
-
-/*****************************************************************************
- * Receive data handling
- *****************************************************************************/
-
-/* Queue a skb in order. We come here only if the skb has an L2TP sequence
- * number.
- */
-static void pppol2tp_recv_queue_skb(struct pppol2tp_session *session, struct sk_buff *skb)
-{
-	struct sk_buff *skbp;
-	struct sk_buff *tmp;
-	u16 ns = PPPOL2TP_SKB_CB(skb)->ns;
-
-	spin_lock_bh(&session->reorder_q.lock);
-	skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
-		if (PPPOL2TP_SKB_CB(skbp)->ns > ns) {
-			__skb_queue_before(&session->reorder_q, skbp, skb);
-			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
-			       "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
-			       session->name, ns, PPPOL2TP_SKB_CB(skbp)->ns,
-			       skb_queue_len(&session->reorder_q));
-			session->stats.rx_oos_packets++;
-			goto out;
-		}
-	}
-
-	__skb_queue_tail(&session->reorder_q, skb);
-
-out:
-	spin_unlock_bh(&session->reorder_q.lock);
-}
-
-/* Dequeue a single skb.
- */
-static void pppol2tp_recv_dequeue_skb(struct pppol2tp_session *session, struct sk_buff *skb)
-{
-	struct pppol2tp_tunnel *tunnel = session->tunnel;
-	int length = PPPOL2TP_SKB_CB(skb)->length;
-	struct sock *session_sock = NULL;
-
-	/* We're about to requeue the skb, so return resources
-	 * to its current owner (a socket receive buffer).
-	 */
-	skb_orphan(skb);
-
-	tunnel->stats.rx_packets++;
-	tunnel->stats.rx_bytes += length;
-	session->stats.rx_packets++;
-	session->stats.rx_bytes += length;
-
-	if (PPPOL2TP_SKB_CB(skb)->has_seq) {
-		/* Bump our Nr */
-		session->nr++;
-		PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
-		       "%s: updated nr to %hu\n", session->name, session->nr);
-	}
-
-	/* If the socket is bound, send it in to PPP's input queue. Otherwise
-	 * queue it on the session socket.
-	 */
-	session_sock = session->sock;
-	if (session_sock->sk_state & PPPOX_BOUND) {
-		struct pppox_sock *po;
-		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
-		       "%s: recv %d byte data frame, passing to ppp\n",
-		       session->name, length);
-
-		/* We need to forget all info related to the L2TP packet
-		 * gathered in the skb as we are going to reuse the same
-		 * skb for the inner packet.
-		 * Namely we need to:
-		 * - reset xfrm (IPSec) information as it applies to
-		 *   the outer L2TP packet and not to the inner one
-		 * - release the dst to force a route lookup on the inner
-		 *   IP packet since skb->dst currently points to the dst
-		 *   of the UDP tunnel
-		 * - reset netfilter information as it doesn't apply
-		 *   to the inner packet either
-		 */
-		secpath_reset(skb);
-		skb_dst_drop(skb);
-		nf_reset(skb);
-
-		po = pppox_sk(session_sock);
-		ppp_input(&po->chan, skb);
-	} else {
-		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_INFO,
-		       "%s: socket not bound\n", session->name);
-
-		/* Not bound. Nothing we can do, so discard. */
-		session->stats.rx_errors++;
-		kfree_skb(skb);
-	}
-
-	sock_put(session->sock);
-}
-
-/* Dequeue skbs from the session's reorder_q, subject to packet order.
- * Skbs that have been in the queue for too long are simply discarded.
- */
-static void pppol2tp_recv_dequeue(struct pppol2tp_session *session)
-{
-	struct sk_buff *skb;
-	struct sk_buff *tmp;
-
-	/* If the pkt at the head of the queue has the nr that we
-	 * expect to send up next, dequeue it and any other
-	 * in-sequence packets behind it.
-	 */
-	spin_lock_bh(&session->reorder_q.lock);
-	skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
-		if (time_after(jiffies, PPPOL2TP_SKB_CB(skb)->expires)) {
-			session->stats.rx_seq_discards++;
-			session->stats.rx_errors++;
-			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
-			       "%s: oos pkt %hu len %d discarded (too old), "
-			       "waiting for %hu, reorder_q_len=%d\n",
-			       session->name, PPPOL2TP_SKB_CB(skb)->ns,
-			       PPPOL2TP_SKB_CB(skb)->length, session->nr,
-			       skb_queue_len(&session->reorder_q));
-			__skb_unlink(skb, &session->reorder_q);
-			kfree_skb(skb);
-			sock_put(session->sock);
-			continue;
-		}
-
-		if (PPPOL2TP_SKB_CB(skb)->has_seq) {
-			if (PPPOL2TP_SKB_CB(skb)->ns != session->nr) {
-				PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
-				       "%s: holding oos pkt %hu len %d, "
-				       "waiting for %hu, reorder_q_len=%d\n",
-				       session->name, PPPOL2TP_SKB_CB(skb)->ns,
-				       PPPOL2TP_SKB_CB(skb)->length, session->nr,
-				       skb_queue_len(&session->reorder_q));
-				goto out;
-			}
-		}
-		__skb_unlink(skb, &session->reorder_q);
-
-		/* Process the skb. We release the queue lock while we
-		 * do so to let other contexts process the queue.
-		 */
-		spin_unlock_bh(&session->reorder_q.lock);
-		pppol2tp_recv_dequeue_skb(session, skb);
-		spin_lock_bh(&session->reorder_q.lock);
-	}
-
-out:
-	spin_unlock_bh(&session->reorder_q.lock);
-}
-
-static inline int pppol2tp_verify_udp_checksum(struct sock *sk,
-					       struct sk_buff *skb)
-{
-	struct udphdr *uh = udp_hdr(skb);
-	u16 ulen = ntohs(uh->len);
-	struct inet_sock *inet;
-	__wsum psum;
-
-	if (sk->sk_no_check || skb_csum_unnecessary(skb) || !uh->check)
-		return 0;
-
-	inet = inet_sk(sk);
-	psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, ulen,
-				  IPPROTO_UDP, 0);
-
-	if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
-	    !csum_fold(csum_add(psum, skb->csum)))
-		return 0;
-
-	skb->csum = psum;
-
-	return __skb_checksum_complete(skb);
-}
-
-/* Internal receive frame. Do the real work of receiving an L2TP data frame
- * here. The skb is not on a list when we get here.
- * Returns 0 if the packet was a data packet and was successfully passed on.
- * Returns 1 if the packet was not a good data packet and could not be
- * forwarded.  All such packets are passed up to userspace to deal with.
- */
-static int pppol2tp_recv_core(struct sock *sock, struct sk_buff *skb)
-{
-	struct pppol2tp_session *session = NULL;
-	struct pppol2tp_tunnel *tunnel;
-	unsigned char *ptr, *optr;
-	u16 hdrflags;
-	u16 tunnel_id, session_id;
-	int length;
-	int offset;
-
-	tunnel = pppol2tp_sock_to_tunnel(sock);
-	if (tunnel == NULL)
-		goto no_tunnel;
-
-	if (tunnel->sock && pppol2tp_verify_udp_checksum(tunnel->sock, skb))
-		goto discard_bad_csum;
-
-	/* UDP always verifies the packet length. */
-	__skb_pull(skb, sizeof(struct udphdr));
-
-	/* Short packet? */
-	if (!pskb_may_pull(skb, 12)) {
-		PRINTK(tunnel->debug, PPPOL2TP_MSG_DATA, KERN_INFO,
-		       "%s: recv short packet (len=%d)\n", tunnel->name, skb->len);
-		goto error;
-	}
-
-	/* Point to L2TP header */
-	optr = ptr = skb->data;
-
-	/* Get L2TP header flags */
-	hdrflags = ntohs(*(__be16*)ptr);
-
-	/* Trace packet contents, if enabled */
-	if (tunnel->debug & PPPOL2TP_MSG_DATA) {
-		length = min(16u, skb->len);
-		if (!pskb_may_pull(skb, length))
-			goto error;
-
-		printk(KERN_DEBUG "%s: recv: ", tunnel->name);
-
-		offset = 0;
-		do {
-			printk(" %02X", ptr[offset]);
-		} while (++offset < length);
-
-		printk("\n");
-	}
-
-	/* Get length of L2TP packet */
-	length = skb->len;
-
-	/* If type is control packet, it is handled by userspace. */
-	if (hdrflags & L2TP_HDRFLAG_T) {
-		PRINTK(tunnel->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
-		       "%s: recv control packet, len=%d\n", tunnel->name, length);
-		goto error;
-	}
-
-	/* Skip flags */
-	ptr += 2;
-
-	/* If length is present, skip it */
-	if (hdrflags & L2TP_HDRFLAG_L)
-		ptr += 2;
-
-	/* Extract tunnel and session ID */
-	tunnel_id = ntohs(*(__be16 *) ptr);
-	ptr += 2;
-	session_id = ntohs(*(__be16 *) ptr);
-	ptr += 2;
-
-	/* Find the session context */
-	session = pppol2tp_session_find(tunnel, session_id);
-	if (!session) {
-		/* Not found? Pass to userspace to deal with */
-		PRINTK(tunnel->debug, PPPOL2TP_MSG_DATA, KERN_INFO,
-		       "%s: no socket found (%hu/%hu). Passing up.\n",
-		       tunnel->name, tunnel_id, session_id);
-		goto error;
-	}
-	sock_hold(session->sock);
-
-	/* The ref count on the socket was increased by the above call since
-	 * we now hold a pointer to the session. Take care to do sock_put()
-	 * when exiting this function from now on...
-	 */
-
-	/* Handle the optional sequence numbers.  If we are the LAC,
-	 * enable/disable sequence numbers under the control of the LNS.  If
-	 * no sequence numbers present but we were expecting them, discard
-	 * frame.
-	 */
-	if (hdrflags & L2TP_HDRFLAG_S) {
-		u16 ns, nr;
-		ns = ntohs(*(__be16 *) ptr);
-		ptr += 2;
-		nr = ntohs(*(__be16 *) ptr);
-		ptr += 2;
-
-		/* Received a packet with sequence numbers. If we're the LNS,
-		 * check if we sre sending sequence numbers and if not,
-		 * configure it so.
-		 */
-		if ((!session->lns_mode) && (!session->send_seq)) {
-			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_INFO,
-			       "%s: requested to enable seq numbers by LNS\n",
-			       session->name);
-			session->send_seq = -1;
-		}
-
-		/* Store L2TP info in the skb */
-		PPPOL2TP_SKB_CB(skb)->ns = ns;
-		PPPOL2TP_SKB_CB(skb)->nr = nr;
-		PPPOL2TP_SKB_CB(skb)->has_seq = 1;
-
-		PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
-		       "%s: recv data ns=%hu, nr=%hu, session nr=%hu\n",
-		       session->name, ns, nr, session->nr);
-	} else {
-		/* No sequence numbers.
-		 * If user has configured mandatory sequence numbers, discard.
-		 */
-		if (session->recv_seq) {
-			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_WARNING,
-			       "%s: recv data has no seq numbers when required. "
-			       "Discarding\n", session->name);
-			session->stats.rx_seq_discards++;
-			goto discard;
-		}
-
-		/* If we're the LAC and we're sending sequence numbers, the
-		 * LNS has requested that we no longer send sequence numbers.
-		 * If we're the LNS and we're sending sequence numbers, the
-		 * LAC is broken. Discard the frame.
-		 */
-		if ((!session->lns_mode) && (session->send_seq)) {
-			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_INFO,
-			       "%s: requested to disable seq numbers by LNS\n",
-			       session->name);
-			session->send_seq = 0;
-		} else if (session->send_seq) {
-			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_WARNING,
-			       "%s: recv data has no seq numbers when required. "
-			       "Discarding\n", session->name);
-			session->stats.rx_seq_discards++;
-			goto discard;
-		}
-
-		/* Store L2TP info in the skb */
-		PPPOL2TP_SKB_CB(skb)->has_seq = 0;
-	}
-
-	/* If offset bit set, skip it. */
-	if (hdrflags & L2TP_HDRFLAG_O) {
-		offset = ntohs(*(__be16 *)ptr);
-		ptr += 2 + offset;
-	}
-
-	offset = ptr - optr;
-	if (!pskb_may_pull(skb, offset))
-		goto discard;
-
-	__skb_pull(skb, offset);
-
-	/* Skip PPP header, if present.	 In testing, Microsoft L2TP clients
-	 * don't send the PPP header (PPP header compression enabled), but
-	 * other clients can include the header. So we cope with both cases
-	 * here. The PPP header is always FF03 when using L2TP.
-	 *
-	 * Note that skb->data[] isn't dereferenced from a u16 ptr here since
-	 * the field may be unaligned.
-	 */
-	if (!pskb_may_pull(skb, 2))
-		goto discard;
-
-	if ((skb->data[0] == 0xff) && (skb->data[1] == 0x03))
-		skb_pull(skb, 2);
-
-	/* Prepare skb for adding to the session's reorder_q.  Hold
-	 * packets for max reorder_timeout or 1 second if not
-	 * reordering.
-	 */
-	PPPOL2TP_SKB_CB(skb)->length = length;
-	PPPOL2TP_SKB_CB(skb)->expires = jiffies +
-		(session->reorder_timeout ? session->reorder_timeout : HZ);
-
-	/* Add packet to the session's receive queue. Reordering is done here, if
-	 * enabled. Saved L2TP protocol info is stored in skb->sb[].
-	 */
-	if (PPPOL2TP_SKB_CB(skb)->has_seq) {
-		if (session->reorder_timeout != 0) {
-			/* Packet reordering enabled. Add skb to session's
-			 * reorder queue, in order of ns.
-			 */
-			pppol2tp_recv_queue_skb(session, skb);
-		} else {
-			/* Packet reordering disabled. Discard out-of-sequence
-			 * packets
-			 */
-			if (PPPOL2TP_SKB_CB(skb)->ns != session->nr) {
-				session->stats.rx_seq_discards++;
-				PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
-				       "%s: oos pkt %hu len %d discarded, "
-				       "waiting for %hu, reorder_q_len=%d\n",
-				       session->name, PPPOL2TP_SKB_CB(skb)->ns,
-				       PPPOL2TP_SKB_CB(skb)->length, session->nr,
-				       skb_queue_len(&session->reorder_q));
-				goto discard;
-			}
-			skb_queue_tail(&session->reorder_q, skb);
-		}
-	} else {
-		/* No sequence numbers. Add the skb to the tail of the
-		 * reorder queue. This ensures that it will be
-		 * delivered after all previous sequenced skbs.
-		 */
-		skb_queue_tail(&session->reorder_q, skb);
-	}
-
-	/* Try to dequeue as many skbs from reorder_q as we can. */
-	pppol2tp_recv_dequeue(session);
-	sock_put(sock);
-
-	return 0;
-
-discard:
-	session->stats.rx_errors++;
-	kfree_skb(skb);
-	sock_put(session->sock);
-	sock_put(sock);
-
-	return 0;
-
-discard_bad_csum:
-	LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
-	UDP_INC_STATS_USER(&init_net, UDP_MIB_INERRORS, 0);
-	tunnel->stats.rx_errors++;
-	kfree_skb(skb);
-	sock_put(sock);
-
-	return 0;
-
-error:
-	/* Put UDP header back */
-	__skb_push(skb, sizeof(struct udphdr));
-	sock_put(sock);
-
-no_tunnel:
-	return 1;
-}
-
-/* UDP encapsulation receive handler. See net/ipv4/udp.c.
- * Return codes:
- * 0 : success.
- * <0: error
- * >0: skb should be passed up to userspace as UDP.
- */
-static int pppol2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
-{
-	struct pppol2tp_tunnel *tunnel;
-
-	tunnel = pppol2tp_sock_to_tunnel(sk);
-	if (tunnel == NULL)
-		goto pass_up;
-
-	PRINTK(tunnel->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
-	       "%s: received %d bytes\n", tunnel->name, skb->len);
-
-	if (pppol2tp_recv_core(sk, skb))
-		goto pass_up_put;
-
-	sock_put(sk);
-	return 0;
-
-pass_up_put:
-	sock_put(sk);
-pass_up:
-	return 1;
-}
-
-/* Receive message. This is the recvmsg for the PPPoL2TP socket.
- */
-static int pppol2tp_recvmsg(struct kiocb *iocb, struct socket *sock,
-			    struct msghdr *msg, size_t len,
-			    int flags)
-{
-	int err;
-	struct sk_buff *skb;
-	struct sock *sk = sock->sk;
-
-	err = -EIO;
-	if (sk->sk_state & PPPOX_BOUND)
-		goto end;
-
-	msg->msg_namelen = 0;
-
-	err = 0;
-	skb = skb_recv_datagram(sk, flags & ~MSG_DONTWAIT,
-				flags & MSG_DONTWAIT, &err);
-	if (!skb)
-		goto end;
-
-	if (len > skb->len)
-		len = skb->len;
-	else if (len < skb->len)
-		msg->msg_flags |= MSG_TRUNC;
-
-	err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, len);
-	if (likely(err == 0))
-		err = len;
-
-	kfree_skb(skb);
-end:
-	return err;
-}
-
-/************************************************************************
- * Transmit handling
- ***********************************************************************/
-
-/* Tell how big L2TP headers are for a particular session. This
- * depends on whether sequence numbers are being used.
- */
-static inline int pppol2tp_l2tp_header_len(struct pppol2tp_session *session)
-{
-	if (session->send_seq)
-		return PPPOL2TP_L2TP_HDR_SIZE_SEQ;
-
-	return PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
-}
-
-/* Build an L2TP header for the session into the buffer provided.
- */
-static void pppol2tp_build_l2tp_header(struct pppol2tp_session *session,
-				       void *buf)
-{
-	__be16 *bufp = buf;
-	u16 flags = L2TP_HDR_VER;
-
-	if (session->send_seq)
-		flags |= L2TP_HDRFLAG_S;
-
-	/* Setup L2TP header.
-	 * FIXME: Can this ever be unaligned? Is direct dereferencing of
-	 * 16-bit header fields safe here for all architectures?
-	 */
-	*bufp++ = htons(flags);
-	*bufp++ = htons(session->tunnel_addr.d_tunnel);
-	*bufp++ = htons(session->tunnel_addr.d_session);
-	if (session->send_seq) {
-		*bufp++ = htons(session->ns);
-		*bufp++ = 0;
-		session->ns++;
-		PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
-		       "%s: updated ns to %hu\n", session->name, session->ns);
-	}
-}
-
-/* This is the sendmsg for the PPPoL2TP pppol2tp_session socket.  We come here
- * when a user application does a sendmsg() on the session socket. L2TP and
- * PPP headers must be inserted into the user's data.
- */
-static int pppol2tp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *m,
-			    size_t total_len)
-{
-	static const unsigned char ppph[2] = { 0xff, 0x03 };
-	struct sock *sk = sock->sk;
-	struct inet_sock *inet;
-	__wsum csum;
-	struct sk_buff *skb;
-	int error;
-	int hdr_len;
-	struct pppol2tp_session *session;
-	struct pppol2tp_tunnel *tunnel;
-	struct udphdr *uh;
-	unsigned int len;
-	struct sock *sk_tun;
-	u16 udp_len;
-
-	error = -ENOTCONN;
-	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED))
-		goto error;
-
-	/* Get session and tunnel contexts */
-	error = -EBADF;
-	session = pppol2tp_sock_to_session(sk);
-	if (session == NULL)
-		goto error;
-
-	sk_tun = session->tunnel_sock;
-	tunnel = pppol2tp_sock_to_tunnel(sk_tun);
-	if (tunnel == NULL)
-		goto error_put_sess;
-
-	/* What header length is configured for this session? */
-	hdr_len = pppol2tp_l2tp_header_len(session);
-
-	/* Allocate a socket buffer */
-	error = -ENOMEM;
-	skb = sock_wmalloc(sk, NET_SKB_PAD + sizeof(struct iphdr) +
-			   sizeof(struct udphdr) + hdr_len +
-			   sizeof(ppph) + total_len,
-			   0, GFP_KERNEL);
-	if (!skb)
-		goto error_put_sess_tun;
-
-	/* Reserve space for headers. */
-	skb_reserve(skb, NET_SKB_PAD);
-	skb_reset_network_header(skb);
-	skb_reserve(skb, sizeof(struct iphdr));
-	skb_reset_transport_header(skb);
-
-	/* Build UDP header */
-	inet = inet_sk(sk_tun);
-	udp_len = hdr_len + sizeof(ppph) + total_len;
-	uh = (struct udphdr *) skb->data;
-	uh->source = inet->inet_sport;
-	uh->dest = inet->inet_dport;
-	uh->len = htons(udp_len);
-	uh->check = 0;
-	skb_put(skb, sizeof(struct udphdr));
-
-	/* Build L2TP header */
-	pppol2tp_build_l2tp_header(session, skb->data);
-	skb_put(skb, hdr_len);
-
-	/* Add PPP header */
-	skb->data[0] = ppph[0];
-	skb->data[1] = ppph[1];
-	skb_put(skb, 2);
-
-	/* Copy user data into skb */
-	error = memcpy_fromiovec(skb->data, m->msg_iov, total_len);
-	if (error < 0) {
-		kfree_skb(skb);
-		goto error_put_sess_tun;
-	}
-	skb_put(skb, total_len);
-
-	/* Calculate UDP checksum if configured to do so */
-	if (sk_tun->sk_no_check == UDP_CSUM_NOXMIT)
-		skb->ip_summed = CHECKSUM_NONE;
-	else if (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM)) {
-		skb->ip_summed = CHECKSUM_COMPLETE;
-		csum = skb_checksum(skb, 0, udp_len, 0);
-		uh->check = csum_tcpudp_magic(inet->inet_saddr,
-					      inet->inet_daddr,
-					      udp_len, IPPROTO_UDP, csum);
-		if (uh->check == 0)
-			uh->check = CSUM_MANGLED_0;
-	} else {
-		skb->ip_summed = CHECKSUM_PARTIAL;
-		skb->csum_start = skb_transport_header(skb) - skb->head;
-		skb->csum_offset = offsetof(struct udphdr, check);
-		uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
-					       inet->inet_daddr,
-					       udp_len, IPPROTO_UDP, 0);
-	}
-
-	/* Debug */
-	if (session->send_seq)
-		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
-		       "%s: send %Zd bytes, ns=%hu\n", session->name,
-		       total_len, session->ns - 1);
-	else
-		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
-		       "%s: send %Zd bytes\n", session->name, total_len);
-
-	if (session->debug & PPPOL2TP_MSG_DATA) {
-		int i;
-		unsigned char *datap = skb->data;
-
-		printk(KERN_DEBUG "%s: xmit:", session->name);
-		for (i = 0; i < total_len; i++) {
-			printk(" %02X", *datap++);
-			if (i == 15) {
-				printk(" ...");
-				break;
-			}
-		}
-		printk("\n");
-	}
-
-	/* Queue the packet to IP for output */
-	len = skb->len;
-	error = ip_queue_xmit(skb, 1);
-
-	/* Update stats */
-	if (error >= 0) {
-		tunnel->stats.tx_packets++;
-		tunnel->stats.tx_bytes += len;
-		session->stats.tx_packets++;
-		session->stats.tx_bytes += len;
-	} else {
-		tunnel->stats.tx_errors++;
-		session->stats.tx_errors++;
-	}
-
-	return error;
-
-error_put_sess_tun:
-	sock_put(session->tunnel_sock);
-error_put_sess:
-	sock_put(sk);
-error:
-	return error;
-}
-
-/* Automatically called when the skb is freed.
- */
-static void pppol2tp_sock_wfree(struct sk_buff *skb)
-{
-	sock_put(skb->sk);
-}
-
-/* For data skbs that we transmit, we associate with the tunnel socket
- * but don't do accounting.
- */
-static inline void pppol2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
-{
-	sock_hold(sk);
-	skb->sk = sk;
-	skb->destructor = pppol2tp_sock_wfree;
-}
-
-/* Transmit function called by generic PPP driver.  Sends PPP frame
- * over PPPoL2TP socket.
- *
- * This is almost the same as pppol2tp_sendmsg(), but rather than
- * being called with a msghdr from userspace, it is called with a skb
- * from the kernel.
- *
- * The supplied skb from ppp doesn't have enough headroom for the
- * insertion of L2TP, UDP and IP headers so we need to allocate more
- * headroom in the skb. This will create a cloned skb. But we must be
- * careful in the error case because the caller will expect to free
- * the skb it supplied, not our cloned skb. So we take care to always
- * leave the original skb unfreed if we return an error.
- */
-static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
-{
-	static const u8 ppph[2] = { 0xff, 0x03 };
-	struct sock *sk = (struct sock *) chan->private;
-	struct sock *sk_tun;
-	int hdr_len;
-	u16 udp_len;
-	struct pppol2tp_session *session;
-	struct pppol2tp_tunnel *tunnel;
-	int rc;
-	int headroom;
-	int data_len = skb->len;
-	struct inet_sock *inet;
-	__wsum csum;
-	struct udphdr *uh;
-	unsigned int len;
-	int old_headroom;
-	int new_headroom;
-
-	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED))
-		goto abort;
-
-	/* Get session and tunnel contexts from the socket */
-	session = pppol2tp_sock_to_session(sk);
-	if (session == NULL)
-		goto abort;
-
-	sk_tun = session->tunnel_sock;
-	if (sk_tun == NULL)
-		goto abort_put_sess;
-	tunnel = pppol2tp_sock_to_tunnel(sk_tun);
-	if (tunnel == NULL)
-		goto abort_put_sess;
-
-	/* What header length is configured for this session? */
-	hdr_len = pppol2tp_l2tp_header_len(session);
-
-	/* Check that there's enough headroom in the skb to insert IP,
-	 * UDP and L2TP and PPP headers. If not enough, expand it to
-	 * make room. Adjust truesize.
-	 */
-	headroom = NET_SKB_PAD + sizeof(struct iphdr) +
-		sizeof(struct udphdr) + hdr_len + sizeof(ppph);
-	old_headroom = skb_headroom(skb);
-	if (skb_cow_head(skb, headroom))
-		goto abort_put_sess_tun;
-
-	new_headroom = skb_headroom(skb);
-	skb_orphan(skb);
-	skb->truesize += new_headroom - old_headroom;
-
-	/* Setup PPP header */
-	__skb_push(skb, sizeof(ppph));
-	skb->data[0] = ppph[0];
-	skb->data[1] = ppph[1];
-
-	/* Setup L2TP header */
-	pppol2tp_build_l2tp_header(session, __skb_push(skb, hdr_len));
-
-	udp_len = sizeof(struct udphdr) + hdr_len + sizeof(ppph) + data_len;
-
-	/* Setup UDP header */
-	inet = inet_sk(sk_tun);
-	__skb_push(skb, sizeof(*uh));
-	skb_reset_transport_header(skb);
-	uh = udp_hdr(skb);
-	uh->source = inet->inet_sport;
-	uh->dest = inet->inet_dport;
-	uh->len = htons(udp_len);
-	uh->check = 0;
-
-	/* Debug */
-	if (session->send_seq)
-		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
-		       "%s: send %d bytes, ns=%hu\n", session->name,
-		       data_len, session->ns - 1);
-	else
-		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
-		       "%s: send %d bytes\n", session->name, data_len);
-
-	if (session->debug & PPPOL2TP_MSG_DATA) {
-		int i;
-		unsigned char *datap = skb->data;
-
-		printk(KERN_DEBUG "%s: xmit:", session->name);
-		for (i = 0; i < data_len; i++) {
-			printk(" %02X", *datap++);
-			if (i == 31) {
-				printk(" ...");
-				break;
-			}
-		}
-		printk("\n");
-	}
-
-	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
-	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
-			      IPSKB_REROUTED);
-	nf_reset(skb);
-
-	/* Get routing info from the tunnel socket */
-	skb_dst_drop(skb);
-	skb_dst_set(skb, dst_clone(__sk_dst_get(sk_tun)));
-	pppol2tp_skb_set_owner_w(skb, sk_tun);
-
-	/* Calculate UDP checksum if configured to do so */
-	if (sk_tun->sk_no_check == UDP_CSUM_NOXMIT)
-		skb->ip_summed = CHECKSUM_NONE;
-	else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
-		 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
-		skb->ip_summed = CHECKSUM_COMPLETE;
-		csum = skb_checksum(skb, 0, udp_len, 0);
-		uh->check = csum_tcpudp_magic(inet->inet_saddr,
-					      inet->inet_daddr,
-					      udp_len, IPPROTO_UDP, csum);
-		if (uh->check == 0)
-			uh->check = CSUM_MANGLED_0;
-	} else {
-		skb->ip_summed = CHECKSUM_PARTIAL;
-		skb->csum_start = skb_transport_header(skb) - skb->head;
-		skb->csum_offset = offsetof(struct udphdr, check);
-		uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
-					       inet->inet_daddr,
-					       udp_len, IPPROTO_UDP, 0);
-	}
-
-	/* Queue the packet to IP for output */
-	len = skb->len;
-	rc = ip_queue_xmit(skb, 1);
-
-	/* Update stats */
-	if (rc >= 0) {
-		tunnel->stats.tx_packets++;
-		tunnel->stats.tx_bytes += len;
-		session->stats.tx_packets++;
-		session->stats.tx_bytes += len;
-	} else {
-		tunnel->stats.tx_errors++;
-		session->stats.tx_errors++;
-	}
-
-	sock_put(sk_tun);
-	sock_put(sk);
-	return 1;
-
-abort_put_sess_tun:
-	sock_put(sk_tun);
-abort_put_sess:
-	sock_put(sk);
-abort:
-	/* Free the original skb */
-	kfree_skb(skb);
-	return 1;
-}
-
-/*****************************************************************************
- * Session (and tunnel control) socket create/destroy.
- *****************************************************************************/
-
-/* When the tunnel UDP socket is closed, all the attached sockets need to go
- * too.
- */
-static void pppol2tp_tunnel_closeall(struct pppol2tp_tunnel *tunnel)
-{
-	int hash;
-	struct hlist_node *walk;
-	struct hlist_node *tmp;
-	struct pppol2tp_session *session;
-	struct sock *sk;
-
-	BUG_ON(tunnel == NULL);
-
-	PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-	       "%s: closing all sessions...\n", tunnel->name);
-
-	write_lock_bh(&tunnel->hlist_lock);
-	for (hash = 0; hash < PPPOL2TP_HASH_SIZE; hash++) {
-again:
-		hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
-			struct sk_buff *skb;
-
-			session = hlist_entry(walk, struct pppol2tp_session, hlist);
-
-			sk = session->sock;
-
-			PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-			       "%s: closing session\n", session->name);
-
-			hlist_del_init(&session->hlist);
-
-			/* Since we should hold the sock lock while
-			 * doing any unbinding, we need to release the
-			 * lock we're holding before taking that lock.
-			 * Hold a reference to the sock so it doesn't
-			 * disappear as we're jumping between locks.
-			 */
-			sock_hold(sk);
-			write_unlock_bh(&tunnel->hlist_lock);
-			lock_sock(sk);
-
-			if (sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND)) {
-				pppox_unbind_sock(sk);
-				sk->sk_state = PPPOX_DEAD;
-				sk->sk_state_change(sk);
-			}
-
-			/* Purge any queued data */
-			skb_queue_purge(&sk->sk_receive_queue);
-			skb_queue_purge(&sk->sk_write_queue);
-			while ((skb = skb_dequeue(&session->reorder_q))) {
-				kfree_skb(skb);
-				sock_put(sk);
-			}
-
-			release_sock(sk);
-			sock_put(sk);
-
-			/* Now restart from the beginning of this hash
-			 * chain.  We always remove a session from the
-			 * list so we are guaranteed to make forward
-			 * progress.
-			 */
-			write_lock_bh(&tunnel->hlist_lock);
-			goto again;
-		}
-	}
-	write_unlock_bh(&tunnel->hlist_lock);
-}
-
-/* Really kill the tunnel.
- * Come here only when all sessions have been cleared from the tunnel.
- */
-static void pppol2tp_tunnel_free(struct pppol2tp_tunnel *tunnel)
-{
-	struct pppol2tp_net *pn = pppol2tp_pernet(tunnel->pppol2tp_net);
-
-	/* Remove from socket list */
-	write_lock_bh(&pn->pppol2tp_tunnel_list_lock);
-	list_del_init(&tunnel->list);
-	write_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
-
-	atomic_dec(&pppol2tp_tunnel_count);
-	kfree(tunnel);
-}
-
-/* Tunnel UDP socket destruct hook.
- * The tunnel context is deleted only when all session sockets have been
- * closed.
- */
-static void pppol2tp_tunnel_destruct(struct sock *sk)
-{
-	struct pppol2tp_tunnel *tunnel;
-
-	tunnel = sk->sk_user_data;
-	if (tunnel == NULL)
-		goto end;
-
-	PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-	       "%s: closing...\n", tunnel->name);
-
-	/* Close all sessions */
-	pppol2tp_tunnel_closeall(tunnel);
-
-	/* No longer an encapsulation socket. See net/ipv4/udp.c */
-	(udp_sk(sk))->encap_type = 0;
-	(udp_sk(sk))->encap_rcv = NULL;
-
-	/* Remove hooks into tunnel socket */
-	tunnel->sock = NULL;
-	sk->sk_destruct = tunnel->old_sk_destruct;
-	sk->sk_user_data = NULL;
-
-	/* Call original (UDP) socket descructor */
-	if (sk->sk_destruct != NULL)
-		(*sk->sk_destruct)(sk);
-
-	pppol2tp_tunnel_dec_refcount(tunnel);
-
-end:
-	return;
-}
-
-/* Really kill the session socket. (Called from sock_put() if
- * refcnt == 0.)
- */
-static void pppol2tp_session_destruct(struct sock *sk)
-{
-	struct pppol2tp_session *session = NULL;
-
-	if (sk->sk_user_data != NULL) {
-		struct pppol2tp_tunnel *tunnel;
-
-		session = sk->sk_user_data;
-		if (session == NULL)
-			goto out;
-
-		BUG_ON(session->magic != L2TP_SESSION_MAGIC);
-
-		/* Don't use pppol2tp_sock_to_tunnel() here to
-		 * get the tunnel context because the tunnel
-		 * socket might have already been closed (its
-		 * sk->sk_user_data will be NULL) so use the
-		 * session's private tunnel ptr instead.
-		 */
-		tunnel = session->tunnel;
-		if (tunnel != NULL) {
-			BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
-
-			/* If session_id is zero, this is a null
-			 * session context, which was created for a
-			 * socket that is being used only to manage
-			 * tunnels.
-			 */
-			if (session->tunnel_addr.s_session != 0) {
-				/* Delete the session socket from the
-				 * hash
-				 */
-				write_lock_bh(&tunnel->hlist_lock);
-				hlist_del_init(&session->hlist);
-				write_unlock_bh(&tunnel->hlist_lock);
-
-				atomic_dec(&pppol2tp_session_count);
-			}
-
-			/* This will delete the tunnel context if this
-			 * is the last session on the tunnel.
-			 */
-			session->tunnel = NULL;
-			session->tunnel_sock = NULL;
-			pppol2tp_tunnel_dec_refcount(tunnel);
-		}
-	}
-
-	kfree(session);
-out:
-	return;
-}
-
-/* Called when the PPPoX socket (session) is closed.
- */
-static int pppol2tp_release(struct socket *sock)
-{
-	struct sock *sk = sock->sk;
-	struct pppol2tp_session *session;
-	int error;
-
-	if (!sk)
-		return 0;
-
-	error = -EBADF;
-	lock_sock(sk);
-	if (sock_flag(sk, SOCK_DEAD) != 0)
-		goto error;
-
-	pppox_unbind_sock(sk);
-
-	/* Signal the death of the socket. */
-	sk->sk_state = PPPOX_DEAD;
-	sock_orphan(sk);
-	sock->sk = NULL;
-
-	session = pppol2tp_sock_to_session(sk);
-
-	/* Purge any queued data */
-	skb_queue_purge(&sk->sk_receive_queue);
-	skb_queue_purge(&sk->sk_write_queue);
-	if (session != NULL) {
-		struct sk_buff *skb;
-		while ((skb = skb_dequeue(&session->reorder_q))) {
-			kfree_skb(skb);
-			sock_put(sk);
-		}
-		sock_put(sk);
-	}
-
-	release_sock(sk);
-
-	/* This will delete the session context via
-	 * pppol2tp_session_destruct() if the socket's refcnt drops to
-	 * zero.
-	 */
-	sock_put(sk);
-
-	return 0;
-
-error:
-	release_sock(sk);
-	return error;
-}
-
-/* Internal function to prepare a tunnel (UDP) socket to have PPPoX
- * sockets attached to it.
- */
-static struct sock *pppol2tp_prepare_tunnel_socket(struct net *net,
-					int fd, u16 tunnel_id, int *error)
-{
-	int err;
-	struct socket *sock = NULL;
-	struct sock *sk;
-	struct pppol2tp_tunnel *tunnel;
-	struct pppol2tp_net *pn;
-	struct sock *ret = NULL;
-
-	/* Get the tunnel UDP socket from the fd, which was opened by
-	 * the userspace L2TP daemon.
-	 */
-	err = -EBADF;
-	sock = sockfd_lookup(fd, &err);
-	if (!sock) {
-		PRINTK(-1, PPPOL2TP_MSG_CONTROL, KERN_ERR,
-		       "tunl %hu: sockfd_lookup(fd=%d) returned %d\n",
-		       tunnel_id, fd, err);
-		goto err;
-	}
-
-	sk = sock->sk;
-
-	/* Quick sanity checks */
-	err = -EPROTONOSUPPORT;
-	if (sk->sk_protocol != IPPROTO_UDP) {
-		PRINTK(-1, PPPOL2TP_MSG_CONTROL, KERN_ERR,
-		       "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
-		       tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
-		goto err;
-	}
-	err = -EAFNOSUPPORT;
-	if (sock->ops->family != AF_INET) {
-		PRINTK(-1, PPPOL2TP_MSG_CONTROL, KERN_ERR,
-		       "tunl %hu: fd %d wrong family, got %d, expected %d\n",
-		       tunnel_id, fd, sock->ops->family, AF_INET);
-		goto err;
-	}
-
-	err = -ENOTCONN;
-
-	/* Check if this socket has already been prepped */
-	tunnel = (struct pppol2tp_tunnel *)sk->sk_user_data;
-	if (tunnel != NULL) {
-		/* User-data field already set */
-		err = -EBUSY;
-		BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
-
-		/* This socket has already been prepped */
-		ret = tunnel->sock;
-		goto out;
-	}
-
-	/* This socket is available and needs prepping. Create a new tunnel
-	 * context and init it.
-	 */
-	sk->sk_user_data = tunnel = kzalloc(sizeof(struct pppol2tp_tunnel), GFP_KERNEL);
-	if (sk->sk_user_data == NULL) {
-		err = -ENOMEM;
-		goto err;
-	}
-
-	tunnel->magic = L2TP_TUNNEL_MAGIC;
-	sprintf(&tunnel->name[0], "tunl %hu", tunnel_id);
-
-	tunnel->stats.tunnel_id = tunnel_id;
-	tunnel->debug = PPPOL2TP_DEFAULT_DEBUG_FLAGS;
-
-	/* Hook on the tunnel socket destructor so that we can cleanup
-	 * if the tunnel socket goes away.
-	 */
-	tunnel->old_sk_destruct = sk->sk_destruct;
-	sk->sk_destruct = pppol2tp_tunnel_destruct;
-
-	tunnel->sock = sk;
-	sk->sk_allocation = GFP_ATOMIC;
-
-	/* Misc init */
-	rwlock_init(&tunnel->hlist_lock);
-
-	/* The net we belong to */
-	tunnel->pppol2tp_net = net;
-	pn = pppol2tp_pernet(net);
-
-	/* Add tunnel to our list */
-	INIT_LIST_HEAD(&tunnel->list);
-	write_lock_bh(&pn->pppol2tp_tunnel_list_lock);
-	list_add(&tunnel->list, &pn->pppol2tp_tunnel_list);
-	write_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
-	atomic_inc(&pppol2tp_tunnel_count);
-
-	/* Bump the reference count. The tunnel context is deleted
-	 * only when this drops to zero.
-	 */
-	pppol2tp_tunnel_inc_refcount(tunnel);
-
-	/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
-	(udp_sk(sk))->encap_type = UDP_ENCAP_L2TPINUDP;
-	(udp_sk(sk))->encap_rcv = pppol2tp_udp_encap_recv;
-
-	ret = tunnel->sock;
-
-	*error = 0;
-out:
-	if (sock)
-		sockfd_put(sock);
-
-	return ret;
-
-err:
-	*error = err;
-	goto out;
-}
-
-static struct proto pppol2tp_sk_proto = {
-	.name	  = "PPPOL2TP",
-	.owner	  = THIS_MODULE,
-	.obj_size = sizeof(struct pppox_sock),
-};
-
-/* socket() handler. Initialize a new struct sock.
- */
-static int pppol2tp_create(struct net *net, struct socket *sock)
-{
-	int error = -ENOMEM;
-	struct sock *sk;
-
-	sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pppol2tp_sk_proto);
-	if (!sk)
-		goto out;
-
-	sock_init_data(sock, sk);
-
-	sock->state  = SS_UNCONNECTED;
-	sock->ops    = &pppol2tp_ops;
-
-	sk->sk_backlog_rcv = pppol2tp_recv_core;
-	sk->sk_protocol	   = PX_PROTO_OL2TP;
-	sk->sk_family	   = PF_PPPOX;
-	sk->sk_state	   = PPPOX_NONE;
-	sk->sk_type	   = SOCK_STREAM;
-	sk->sk_destruct	   = pppol2tp_session_destruct;
-
-	error = 0;
-
-out:
-	return error;
-}
-
-/* connect() handler. Attach a PPPoX socket to a tunnel UDP socket
- */
-static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
-			    int sockaddr_len, int flags)
-{
-	struct sock *sk = sock->sk;
-	struct sockaddr_pppol2tp *sp = (struct sockaddr_pppol2tp *) uservaddr;
-	struct pppox_sock *po = pppox_sk(sk);
-	struct sock *tunnel_sock = NULL;
-	struct pppol2tp_session *session = NULL;
-	struct pppol2tp_tunnel *tunnel;
-	struct dst_entry *dst;
-	int error = 0;
-
-	lock_sock(sk);
-
-	error = -EINVAL;
-	if (sp->sa_protocol != PX_PROTO_OL2TP)
-		goto end;
-
-	/* Check for already bound sockets */
-	error = -EBUSY;
-	if (sk->sk_state & PPPOX_CONNECTED)
-		goto end;
-
-	/* We don't supporting rebinding anyway */
-	error = -EALREADY;
-	if (sk->sk_user_data)
-		goto end; /* socket is already attached */
-
-	/* Don't bind if s_tunnel is 0 */
-	error = -EINVAL;
-	if (sp->pppol2tp.s_tunnel == 0)
-		goto end;
-
-	/* Special case: prepare tunnel socket if s_session and
-	 * d_session is 0. Otherwise look up tunnel using supplied
-	 * tunnel id.
-	 */
-	if ((sp->pppol2tp.s_session == 0) && (sp->pppol2tp.d_session == 0)) {
-		tunnel_sock = pppol2tp_prepare_tunnel_socket(sock_net(sk),
-							     sp->pppol2tp.fd,
-							     sp->pppol2tp.s_tunnel,
-							     &error);
-		if (tunnel_sock == NULL)
-			goto end;
-
-		sock_hold(tunnel_sock);
-		tunnel = tunnel_sock->sk_user_data;
-	} else {
-		tunnel = pppol2tp_tunnel_find(sock_net(sk), sp->pppol2tp.s_tunnel);
-
-		/* Error if we can't find the tunnel */
-		error = -ENOENT;
-		if (tunnel == NULL)
-			goto end;
-
-		tunnel_sock = tunnel->sock;
-	}
-
-	/* Check that this session doesn't already exist */
-	error = -EEXIST;
-	session = pppol2tp_session_find(tunnel, sp->pppol2tp.s_session);
-	if (session != NULL)
-		goto end;
-
-	/* Allocate and initialize a new session context. */
-	session = kzalloc(sizeof(struct pppol2tp_session), GFP_KERNEL);
-	if (session == NULL) {
-		error = -ENOMEM;
-		goto end;
-	}
-
-	skb_queue_head_init(&session->reorder_q);
-
-	session->magic	     = L2TP_SESSION_MAGIC;
-	session->owner	     = current->pid;
-	session->sock	     = sk;
-	session->tunnel	     = tunnel;
-	session->tunnel_sock = tunnel_sock;
-	session->tunnel_addr = sp->pppol2tp;
-	sprintf(&session->name[0], "sess %hu/%hu",
-		session->tunnel_addr.s_tunnel,
-		session->tunnel_addr.s_session);
-
-	session->stats.tunnel_id  = session->tunnel_addr.s_tunnel;
-	session->stats.session_id = session->tunnel_addr.s_session;
-
-	INIT_HLIST_NODE(&session->hlist);
-
-	/* Inherit debug options from tunnel */
-	session->debug = tunnel->debug;
-
-	/* Default MTU must allow space for UDP/L2TP/PPP
-	 * headers.
-	 */
-	session->mtu = session->mru = 1500 - PPPOL2TP_HEADER_OVERHEAD;
-
-	/* If PMTU discovery was enabled, use the MTU that was discovered */
-	dst = sk_dst_get(sk);
-	if (dst != NULL) {
-		u32 pmtu = dst_mtu(__sk_dst_get(sk));
-		if (pmtu != 0)
-			session->mtu = session->mru = pmtu -
-				PPPOL2TP_HEADER_OVERHEAD;
-		dst_release(dst);
-	}
-
-	/* Special case: if source & dest session_id == 0x0000, this socket is
-	 * being created to manage the tunnel. Don't add the session to the
-	 * session hash list, just set up the internal context for use by
-	 * ioctl() and sockopt() handlers.
-	 */
-	if ((session->tunnel_addr.s_session == 0) &&
-	    (session->tunnel_addr.d_session == 0)) {
-		error = 0;
-		sk->sk_user_data = session;
-		goto out_no_ppp;
-	}
-
-	/* Get tunnel context from the tunnel socket */
-	tunnel = pppol2tp_sock_to_tunnel(tunnel_sock);
-	if (tunnel == NULL) {
-		error = -EBADF;
-		goto end;
-	}
-
-	/* Right now, because we don't have a way to push the incoming skb's
-	 * straight through the UDP layer, the only header we need to worry
-	 * about is the L2TP header. This size is different depending on
-	 * whether sequence numbers are enabled for the data channel.
-	 */
-	po->chan.hdrlen = PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
-
-	po->chan.private = sk;
-	po->chan.ops	 = &pppol2tp_chan_ops;
-	po->chan.mtu	 = session->mtu;
-
-	error = ppp_register_net_channel(sock_net(sk), &po->chan);
-	if (error)
-		goto end_put_tun;
-
-	/* This is how we get the session context from the socket. */
-	sk->sk_user_data = session;
-
-	/* Add session to the tunnel's hash list */
-	write_lock_bh(&tunnel->hlist_lock);
-	hlist_add_head(&session->hlist,
-		       pppol2tp_session_id_hash(tunnel,
-						session->tunnel_addr.s_session));
-	write_unlock_bh(&tunnel->hlist_lock);
-
-	atomic_inc(&pppol2tp_session_count);
-
-out_no_ppp:
-	pppol2tp_tunnel_inc_refcount(tunnel);
-	sk->sk_state = PPPOX_CONNECTED;
-	PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-	       "%s: created\n", session->name);
-
-end_put_tun:
-	sock_put(tunnel_sock);
-end:
-	release_sock(sk);
-
-	if (error != 0) {
-		if (session)
-			PRINTK(session->debug,
-				PPPOL2TP_MSG_CONTROL, KERN_WARNING,
-				"%s: connect failed: %d\n",
-				session->name, error);
-		else
-			PRINTK(-1, PPPOL2TP_MSG_CONTROL, KERN_WARNING,
-				"connect failed: %d\n", error);
-	}
-
-	return error;
-}
-
-/* getname() support.
- */
-static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
-			    int *usockaddr_len, int peer)
-{
-	int len = sizeof(struct sockaddr_pppol2tp);
-	struct sockaddr_pppol2tp sp;
-	int error = 0;
-	struct pppol2tp_session *session;
-
-	error = -ENOTCONN;
-	if (sock->sk->sk_state != PPPOX_CONNECTED)
-		goto end;
-
-	session = pppol2tp_sock_to_session(sock->sk);
-	if (session == NULL) {
-		error = -EBADF;
-		goto end;
-	}
-
-	sp.sa_family	= AF_PPPOX;
-	sp.sa_protocol	= PX_PROTO_OL2TP;
-	memcpy(&sp.pppol2tp, &session->tunnel_addr,
-	       sizeof(struct pppol2tp_addr));
-
-	memcpy(uaddr, &sp, len);
-
-	*usockaddr_len = len;
-
-	error = 0;
-	sock_put(sock->sk);
-
-end:
-	return error;
-}
-
-/****************************************************************************
- * ioctl() handlers.
- *
- * The PPPoX socket is created for L2TP sessions: tunnels have their own UDP
- * sockets. However, in order to control kernel tunnel features, we allow
- * userspace to create a special "tunnel" PPPoX socket which is used for
- * control only.  Tunnel PPPoX sockets have session_id == 0 and simply allow
- * the user application to issue L2TP setsockopt(), getsockopt() and ioctl()
- * calls.
- ****************************************************************************/
-
-/* Session ioctl helper.
- */
-static int pppol2tp_session_ioctl(struct pppol2tp_session *session,
-				  unsigned int cmd, unsigned long arg)
-{
-	struct ifreq ifr;
-	int err = 0;
-	struct sock *sk = session->sock;
-	int val = (int) arg;
-
-	PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_DEBUG,
-	       "%s: pppol2tp_session_ioctl(cmd=%#x, arg=%#lx)\n",
-	       session->name, cmd, arg);
-
-	sock_hold(sk);
-
-	switch (cmd) {
-	case SIOCGIFMTU:
-		err = -ENXIO;
-		if (!(sk->sk_state & PPPOX_CONNECTED))
-			break;
-
-		err = -EFAULT;
-		if (copy_from_user(&ifr, (void __user *) arg, sizeof(struct ifreq)))
-			break;
-		ifr.ifr_mtu = session->mtu;
-		if (copy_to_user((void __user *) arg, &ifr, sizeof(struct ifreq)))
-			break;
-
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: get mtu=%d\n", session->name, session->mtu);
-		err = 0;
-		break;
-
-	case SIOCSIFMTU:
-		err = -ENXIO;
-		if (!(sk->sk_state & PPPOX_CONNECTED))
-			break;
-
-		err = -EFAULT;
-		if (copy_from_user(&ifr, (void __user *) arg, sizeof(struct ifreq)))
-			break;
-
-		session->mtu = ifr.ifr_mtu;
-
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: set mtu=%d\n", session->name, session->mtu);
-		err = 0;
-		break;
-
-	case PPPIOCGMRU:
-		err = -ENXIO;
-		if (!(sk->sk_state & PPPOX_CONNECTED))
-			break;
-
-		err = -EFAULT;
-		if (put_user(session->mru, (int __user *) arg))
-			break;
-
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: get mru=%d\n", session->name, session->mru);
-		err = 0;
-		break;
-
-	case PPPIOCSMRU:
-		err = -ENXIO;
-		if (!(sk->sk_state & PPPOX_CONNECTED))
-			break;
-
-		err = -EFAULT;
-		if (get_user(val,(int __user *) arg))
-			break;
-
-		session->mru = val;
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: set mru=%d\n", session->name, session->mru);
-		err = 0;
-		break;
-
-	case PPPIOCGFLAGS:
-		err = -EFAULT;
-		if (put_user(session->flags, (int __user *) arg))
-			break;
-
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: get flags=%d\n", session->name, session->flags);
-		err = 0;
-		break;
-
-	case PPPIOCSFLAGS:
-		err = -EFAULT;
-		if (get_user(val, (int __user *) arg))
-			break;
-		session->flags = val;
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: set flags=%d\n", session->name, session->flags);
-		err = 0;
-		break;
-
-	case PPPIOCGL2TPSTATS:
-		err = -ENXIO;
-		if (!(sk->sk_state & PPPOX_CONNECTED))
-			break;
-
-		if (copy_to_user((void __user *) arg, &session->stats,
-				 sizeof(session->stats)))
-			break;
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: get L2TP stats\n", session->name);
-		err = 0;
-		break;
-
-	default:
-		err = -ENOSYS;
-		break;
-	}
-
-	sock_put(sk);
-
-	return err;
-}
-
-/* Tunnel ioctl helper.
- *
- * Note the special handling for PPPIOCGL2TPSTATS below. If the ioctl data
- * specifies a session_id, the session ioctl handler is called. This allows an
- * application to retrieve session stats via a tunnel socket.
- */
-static int pppol2tp_tunnel_ioctl(struct pppol2tp_tunnel *tunnel,
-				 unsigned int cmd, unsigned long arg)
-{
-	int err = 0;
-	struct sock *sk = tunnel->sock;
-	struct pppol2tp_ioc_stats stats_req;
-
-	PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_DEBUG,
-	       "%s: pppol2tp_tunnel_ioctl(cmd=%#x, arg=%#lx)\n", tunnel->name,
-	       cmd, arg);
-
-	sock_hold(sk);
-
-	switch (cmd) {
-	case PPPIOCGL2TPSTATS:
-		err = -ENXIO;
-		if (!(sk->sk_state & PPPOX_CONNECTED))
-			break;
-
-		if (copy_from_user(&stats_req, (void __user *) arg,
-				   sizeof(stats_req))) {
-			err = -EFAULT;
-			break;
-		}
-		if (stats_req.session_id != 0) {
-			/* resend to session ioctl handler */
-			struct pppol2tp_session *session =
-				pppol2tp_session_find(tunnel, stats_req.session_id);
-			if (session != NULL)
-				err = pppol2tp_session_ioctl(session, cmd, arg);
-			else
-				err = -EBADR;
-			break;
-		}
-#ifdef CONFIG_XFRM
-		tunnel->stats.using_ipsec = (sk->sk_policy[0] || sk->sk_policy[1]) ? 1 : 0;
-#endif
-		if (copy_to_user((void __user *) arg, &tunnel->stats,
-				 sizeof(tunnel->stats))) {
-			err = -EFAULT;
-			break;
-		}
-		PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: get L2TP stats\n", tunnel->name);
-		err = 0;
-		break;
-
-	default:
-		err = -ENOSYS;
-		break;
-	}
-
-	sock_put(sk);
-
-	return err;
-}
-
-/* Main ioctl() handler.
- * Dispatch to tunnel or session helpers depending on the socket.
- */
-static int pppol2tp_ioctl(struct socket *sock, unsigned int cmd,
-			  unsigned long arg)
-{
-	struct sock *sk = sock->sk;
-	struct pppol2tp_session *session;
-	struct pppol2tp_tunnel *tunnel;
-	int err;
-
-	if (!sk)
-		return 0;
-
-	err = -EBADF;
-	if (sock_flag(sk, SOCK_DEAD) != 0)
-		goto end;
-
-	err = -ENOTCONN;
-	if ((sk->sk_user_data == NULL) ||
-	    (!(sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND))))
-		goto end;
-
-	/* Get session context from the socket */
-	err = -EBADF;
-	session = pppol2tp_sock_to_session(sk);
-	if (session == NULL)
-		goto end;
-
-	/* Special case: if session's session_id is zero, treat ioctl as a
-	 * tunnel ioctl
-	 */
-	if ((session->tunnel_addr.s_session == 0) &&
-	    (session->tunnel_addr.d_session == 0)) {
-		err = -EBADF;
-		tunnel = pppol2tp_sock_to_tunnel(session->tunnel_sock);
-		if (tunnel == NULL)
-			goto end_put_sess;
-
-		err = pppol2tp_tunnel_ioctl(tunnel, cmd, arg);
-		sock_put(session->tunnel_sock);
-		goto end_put_sess;
-	}
-
-	err = pppol2tp_session_ioctl(session, cmd, arg);
-
-end_put_sess:
-	sock_put(sk);
-end:
-	return err;
-}
-
-/*****************************************************************************
- * setsockopt() / getsockopt() support.
- *
- * The PPPoX socket is created for L2TP sessions: tunnels have their own UDP
- * sockets. In order to control kernel tunnel features, we allow userspace to
- * create a special "tunnel" PPPoX socket which is used for control only.
- * Tunnel PPPoX sockets have session_id == 0 and simply allow the user
- * application to issue L2TP setsockopt(), getsockopt() and ioctl() calls.
- *****************************************************************************/
-
-/* Tunnel setsockopt() helper.
- */
-static int pppol2tp_tunnel_setsockopt(struct sock *sk,
-				      struct pppol2tp_tunnel *tunnel,
-				      int optname, int val)
-{
-	int err = 0;
-
-	switch (optname) {
-	case PPPOL2TP_SO_DEBUG:
-		tunnel->debug = val;
-		PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: set debug=%x\n", tunnel->name, tunnel->debug);
-		break;
-
-	default:
-		err = -ENOPROTOOPT;
-		break;
-	}
-
-	return err;
-}
-
-/* Session setsockopt helper.
- */
-static int pppol2tp_session_setsockopt(struct sock *sk,
-				       struct pppol2tp_session *session,
-				       int optname, int val)
-{
-	int err = 0;
-
-	switch (optname) {
-	case PPPOL2TP_SO_RECVSEQ:
-		if ((val != 0) && (val != 1)) {
-			err = -EINVAL;
-			break;
-		}
-		session->recv_seq = val ? -1 : 0;
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: set recv_seq=%d\n", session->name,
-		       session->recv_seq);
-		break;
-
-	case PPPOL2TP_SO_SENDSEQ:
-		if ((val != 0) && (val != 1)) {
-			err = -EINVAL;
-			break;
-		}
-		session->send_seq = val ? -1 : 0;
-		{
-			struct sock *ssk      = session->sock;
-			struct pppox_sock *po = pppox_sk(ssk);
-			po->chan.hdrlen = val ? PPPOL2TP_L2TP_HDR_SIZE_SEQ :
-				PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
-		}
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: set send_seq=%d\n", session->name, session->send_seq);
-		break;
-
-	case PPPOL2TP_SO_LNSMODE:
-		if ((val != 0) && (val != 1)) {
-			err = -EINVAL;
-			break;
-		}
-		session->lns_mode = val ? -1 : 0;
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: set lns_mode=%d\n", session->name,
-		       session->lns_mode);
-		break;
-
-	case PPPOL2TP_SO_DEBUG:
-		session->debug = val;
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: set debug=%x\n", session->name, session->debug);
-		break;
-
-	case PPPOL2TP_SO_REORDERTO:
-		session->reorder_timeout = msecs_to_jiffies(val);
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: set reorder_timeout=%d\n", session->name,
-		       session->reorder_timeout);
-		break;
-
-	default:
-		err = -ENOPROTOOPT;
-		break;
-	}
-
-	return err;
-}
-
-/* Main setsockopt() entry point.
- * Does API checks, then calls either the tunnel or session setsockopt
- * handler, according to whether the PPPoL2TP socket is a for a regular
- * session or the special tunnel type.
- */
-static int pppol2tp_setsockopt(struct socket *sock, int level, int optname,
-			       char __user *optval, unsigned int optlen)
-{
-	struct sock *sk = sock->sk;
-	struct pppol2tp_session *session = sk->sk_user_data;
-	struct pppol2tp_tunnel *tunnel;
-	int val;
-	int err;
-
-	if (level != SOL_PPPOL2TP)
-		return udp_prot.setsockopt(sk, level, optname, optval, optlen);
-
-	if (optlen < sizeof(int))
-		return -EINVAL;
-
-	if (get_user(val, (int __user *)optval))
-		return -EFAULT;
-
-	err = -ENOTCONN;
-	if (sk->sk_user_data == NULL)
-		goto end;
-
-	/* Get session context from the socket */
-	err = -EBADF;
-	session = pppol2tp_sock_to_session(sk);
-	if (session == NULL)
-		goto end;
-
-	/* Special case: if session_id == 0x0000, treat as operation on tunnel
-	 */
-	if ((session->tunnel_addr.s_session == 0) &&
-	    (session->tunnel_addr.d_session == 0)) {
-		err = -EBADF;
-		tunnel = pppol2tp_sock_to_tunnel(session->tunnel_sock);
-		if (tunnel == NULL)
-			goto end_put_sess;
-
-		err = pppol2tp_tunnel_setsockopt(sk, tunnel, optname, val);
-		sock_put(session->tunnel_sock);
-	} else
-		err = pppol2tp_session_setsockopt(sk, session, optname, val);
-
-	err = 0;
-
-end_put_sess:
-	sock_put(sk);
-end:
-	return err;
-}
-
-/* Tunnel getsockopt helper. Called with sock locked.
- */
-static int pppol2tp_tunnel_getsockopt(struct sock *sk,
-				      struct pppol2tp_tunnel *tunnel,
-				      int optname, int *val)
-{
-	int err = 0;
-
-	switch (optname) {
-	case PPPOL2TP_SO_DEBUG:
-		*val = tunnel->debug;
-		PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: get debug=%x\n", tunnel->name, tunnel->debug);
-		break;
-
-	default:
-		err = -ENOPROTOOPT;
-		break;
-	}
-
-	return err;
-}
-
-/* Session getsockopt helper. Called with sock locked.
- */
-static int pppol2tp_session_getsockopt(struct sock *sk,
-				       struct pppol2tp_session *session,
-				       int optname, int *val)
-{
-	int err = 0;
-
-	switch (optname) {
-	case PPPOL2TP_SO_RECVSEQ:
-		*val = session->recv_seq;
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: get recv_seq=%d\n", session->name, *val);
-		break;
-
-	case PPPOL2TP_SO_SENDSEQ:
-		*val = session->send_seq;
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: get send_seq=%d\n", session->name, *val);
-		break;
-
-	case PPPOL2TP_SO_LNSMODE:
-		*val = session->lns_mode;
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: get lns_mode=%d\n", session->name, *val);
-		break;
-
-	case PPPOL2TP_SO_DEBUG:
-		*val = session->debug;
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: get debug=%d\n", session->name, *val);
-		break;
-
-	case PPPOL2TP_SO_REORDERTO:
-		*val = (int) jiffies_to_msecs(session->reorder_timeout);
-		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
-		       "%s: get reorder_timeout=%d\n", session->name, *val);
-		break;
-
-	default:
-		err = -ENOPROTOOPT;
-	}
-
-	return err;
-}
-
-/* Main getsockopt() entry point.
- * Does API checks, then calls either the tunnel or session getsockopt
- * handler, according to whether the PPPoX socket is a for a regular session
- * or the special tunnel type.
- */
-static int pppol2tp_getsockopt(struct socket *sock, int level,
-			       int optname, char __user *optval, int __user *optlen)
-{
-	struct sock *sk = sock->sk;
-	struct pppol2tp_session *session = sk->sk_user_data;
-	struct pppol2tp_tunnel *tunnel;
-	int val, len;
-	int err;
-
-	if (level != SOL_PPPOL2TP)
-		return udp_prot.getsockopt(sk, level, optname, optval, optlen);
-
-	if (get_user(len, (int __user *) optlen))
-		return -EFAULT;
-
-	len = min_t(unsigned int, len, sizeof(int));
-
-	if (len < 0)
-		return -EINVAL;
-
-	err = -ENOTCONN;
-	if (sk->sk_user_data == NULL)
-		goto end;
-
-	/* Get the session context */
-	err = -EBADF;
-	session = pppol2tp_sock_to_session(sk);
-	if (session == NULL)
-		goto end;
-
-	/* Special case: if session_id == 0x0000, treat as operation on tunnel */
-	if ((session->tunnel_addr.s_session == 0) &&
-	    (session->tunnel_addr.d_session == 0)) {
-		err = -EBADF;
-		tunnel = pppol2tp_sock_to_tunnel(session->tunnel_sock);
-		if (tunnel == NULL)
-			goto end_put_sess;
-
-		err = pppol2tp_tunnel_getsockopt(sk, tunnel, optname, &val);
-		sock_put(session->tunnel_sock);
-	} else
-		err = pppol2tp_session_getsockopt(sk, session, optname, &val);
-
-	err = -EFAULT;
-	if (put_user(len, (int __user *) optlen))
-		goto end_put_sess;
-
-	if (copy_to_user((void __user *) optval, &val, len))
-		goto end_put_sess;
-
-	err = 0;
-
-end_put_sess:
-	sock_put(sk);
-end:
-	return err;
-}
-
-/*****************************************************************************
- * /proc filesystem for debug
- *****************************************************************************/
-
-#ifdef CONFIG_PROC_FS
-
-#include <linux/seq_file.h>
-
-struct pppol2tp_seq_data {
-	struct seq_net_private p;
-	struct pppol2tp_tunnel *tunnel;		/* current tunnel */
-	struct pppol2tp_session *session;	/* NULL means get first session in tunnel */
-};
-
-static struct pppol2tp_session *next_session(struct pppol2tp_tunnel *tunnel, struct pppol2tp_session *curr)
-{
-	struct pppol2tp_session *session = NULL;
-	struct hlist_node *walk;
-	int found = 0;
-	int next = 0;
-	int i;
-
-	read_lock_bh(&tunnel->hlist_lock);
-	for (i = 0; i < PPPOL2TP_HASH_SIZE; i++) {
-		hlist_for_each_entry(session, walk, &tunnel->session_hlist[i], hlist) {
-			if (curr == NULL) {
-				found = 1;
-				goto out;
-			}
-			if (session == curr) {
-				next = 1;
-				continue;
-			}
-			if (next) {
-				found = 1;
-				goto out;
-			}
-		}
-	}
-out:
-	read_unlock_bh(&tunnel->hlist_lock);
-	if (!found)
-		session = NULL;
-
-	return session;
-}
-
-static struct pppol2tp_tunnel *next_tunnel(struct pppol2tp_net *pn,
-					   struct pppol2tp_tunnel *curr)
-{
-	struct pppol2tp_tunnel *tunnel = NULL;
-
-	read_lock_bh(&pn->pppol2tp_tunnel_list_lock);
-	if (list_is_last(&curr->list, &pn->pppol2tp_tunnel_list)) {
-		goto out;
-	}
-	tunnel = list_entry(curr->list.next, struct pppol2tp_tunnel, list);
-out:
-	read_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
-
-	return tunnel;
-}
-
-static void *pppol2tp_seq_start(struct seq_file *m, loff_t *offs)
-{
-	struct pppol2tp_seq_data *pd = SEQ_START_TOKEN;
-	struct pppol2tp_net *pn;
-	loff_t pos = *offs;
-
-	if (!pos)
-		goto out;
-
-	BUG_ON(m->private == NULL);
-	pd = m->private;
-	pn = pppol2tp_pernet(seq_file_net(m));
-
-	if (pd->tunnel == NULL) {
-		if (!list_empty(&pn->pppol2tp_tunnel_list))
-			pd->tunnel = list_entry(pn->pppol2tp_tunnel_list.next, struct pppol2tp_tunnel, list);
-	} else {
-		pd->session = next_session(pd->tunnel, pd->session);
-		if (pd->session == NULL) {
-			pd->tunnel = next_tunnel(pn, pd->tunnel);
-		}
-	}
-
-	/* NULL tunnel and session indicates end of list */
-	if ((pd->tunnel == NULL) && (pd->session == NULL))
-		pd = NULL;
-
-out:
-	return pd;
-}
-
-static void *pppol2tp_seq_next(struct seq_file *m, void *v, loff_t *pos)
-{
-	(*pos)++;
-	return NULL;
-}
-
-static void pppol2tp_seq_stop(struct seq_file *p, void *v)
-{
-	/* nothing to do */
-}
-
-static void pppol2tp_seq_tunnel_show(struct seq_file *m, void *v)
-{
-	struct pppol2tp_tunnel *tunnel = v;
-
-	seq_printf(m, "\nTUNNEL '%s', %c %d\n",
-		   tunnel->name,
-		   (tunnel == tunnel->sock->sk_user_data) ? 'Y':'N',
-		   atomic_read(&tunnel->ref_count) - 1);
-	seq_printf(m, " %08x %llu/%llu/%llu %llu/%llu/%llu\n",
-		   tunnel->debug,
-		   (unsigned long long)tunnel->stats.tx_packets,
-		   (unsigned long long)tunnel->stats.tx_bytes,
-		   (unsigned long long)tunnel->stats.tx_errors,
-		   (unsigned long long)tunnel->stats.rx_packets,
-		   (unsigned long long)tunnel->stats.rx_bytes,
-		   (unsigned long long)tunnel->stats.rx_errors);
-}
-
-static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
-{
-	struct pppol2tp_session *session = v;
-
-	seq_printf(m, "  SESSION '%s' %08X/%d %04X/%04X -> "
-		   "%04X/%04X %d %c\n",
-		   session->name,
-		   ntohl(session->tunnel_addr.addr.sin_addr.s_addr),
-		   ntohs(session->tunnel_addr.addr.sin_port),
-		   session->tunnel_addr.s_tunnel,
-		   session->tunnel_addr.s_session,
-		   session->tunnel_addr.d_tunnel,
-		   session->tunnel_addr.d_session,
-		   session->sock->sk_state,
-		   (session == session->sock->sk_user_data) ?
-		   'Y' : 'N');
-	seq_printf(m, "   %d/%d/%c/%c/%s %08x %u\n",
-		   session->mtu, session->mru,
-		   session->recv_seq ? 'R' : '-',
-		   session->send_seq ? 'S' : '-',
-		   session->lns_mode ? "LNS" : "LAC",
-		   session->debug,
-		   jiffies_to_msecs(session->reorder_timeout));
-	seq_printf(m, "   %hu/%hu %llu/%llu/%llu %llu/%llu/%llu\n",
-		   session->nr, session->ns,
-		   (unsigned long long)session->stats.tx_packets,
-		   (unsigned long long)session->stats.tx_bytes,
-		   (unsigned long long)session->stats.tx_errors,
-		   (unsigned long long)session->stats.rx_packets,
-		   (unsigned long long)session->stats.rx_bytes,
-		   (unsigned long long)session->stats.rx_errors);
-}
-
-static int pppol2tp_seq_show(struct seq_file *m, void *v)
-{
-	struct pppol2tp_seq_data *pd = v;
-
-	/* display header on line 1 */
-	if (v == SEQ_START_TOKEN) {
-		seq_puts(m, "PPPoL2TP driver info, " PPPOL2TP_DRV_VERSION "\n");
-		seq_puts(m, "TUNNEL name, user-data-ok session-count\n");
-		seq_puts(m, " debug tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
-		seq_puts(m, "  SESSION name, addr/port src-tid/sid "
-			 "dest-tid/sid state user-data-ok\n");
-		seq_puts(m, "   mtu/mru/rcvseq/sendseq/lns debug reorderto\n");
-		seq_puts(m, "   nr/ns tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
-		goto out;
-	}
-
-	/* Show the tunnel or session context.
-	 */
-	if (pd->session == NULL)
-		pppol2tp_seq_tunnel_show(m, pd->tunnel);
-	else
-		pppol2tp_seq_session_show(m, pd->session);
-
-out:
-	return 0;
-}
-
-static const struct seq_operations pppol2tp_seq_ops = {
-	.start		= pppol2tp_seq_start,
-	.next		= pppol2tp_seq_next,
-	.stop		= pppol2tp_seq_stop,
-	.show		= pppol2tp_seq_show,
-};
-
-/* Called when our /proc file is opened. We allocate data for use when
- * iterating our tunnel / session contexts and store it in the private
- * data of the seq_file.
- */
-static int pppol2tp_proc_open(struct inode *inode, struct file *file)
-{
-	return seq_open_net(inode, file, &pppol2tp_seq_ops,
-			    sizeof(struct pppol2tp_seq_data));
-}
-
-static const struct file_operations pppol2tp_proc_fops = {
-	.owner		= THIS_MODULE,
-	.open		= pppol2tp_proc_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= seq_release_net,
-};
-
-#endif /* CONFIG_PROC_FS */
-
-/*****************************************************************************
- * Init and cleanup
- *****************************************************************************/
-
-static const struct proto_ops pppol2tp_ops = {
-	.family		= AF_PPPOX,
-	.owner		= THIS_MODULE,
-	.release	= pppol2tp_release,
-	.bind		= sock_no_bind,
-	.connect	= pppol2tp_connect,
-	.socketpair	= sock_no_socketpair,
-	.accept		= sock_no_accept,
-	.getname	= pppol2tp_getname,
-	.poll		= datagram_poll,
-	.listen		= sock_no_listen,
-	.shutdown	= sock_no_shutdown,
-	.setsockopt	= pppol2tp_setsockopt,
-	.getsockopt	= pppol2tp_getsockopt,
-	.sendmsg	= pppol2tp_sendmsg,
-	.recvmsg	= pppol2tp_recvmsg,
-	.mmap		= sock_no_mmap,
-	.ioctl		= pppox_ioctl,
-};
-
-static struct pppox_proto pppol2tp_proto = {
-	.create		= pppol2tp_create,
-	.ioctl		= pppol2tp_ioctl
-};
-
-static __net_init int pppol2tp_init_net(struct net *net)
-{
-	struct pppol2tp_net *pn = pppol2tp_pernet(net);
-	struct proc_dir_entry *pde;
-
-	INIT_LIST_HEAD(&pn->pppol2tp_tunnel_list);
-	rwlock_init(&pn->pppol2tp_tunnel_list_lock);
-
-	pde = proc_net_fops_create(net, "pppol2tp", S_IRUGO, &pppol2tp_proc_fops);
-#ifdef CONFIG_PROC_FS
-	if (!pde)
-		return -ENOMEM;
-#endif
-
-	return 0;
-}
-
-static __net_exit void pppol2tp_exit_net(struct net *net)
-{
-	proc_net_remove(net, "pppol2tp");
-}
-
-static struct pernet_operations pppol2tp_net_ops = {
-	.init = pppol2tp_init_net,
-	.exit = pppol2tp_exit_net,
-	.id   = &pppol2tp_net_id,
-	.size = sizeof(struct pppol2tp_net),
-};
-
-static int __init pppol2tp_init(void)
-{
-	int err;
-
-	err = proto_register(&pppol2tp_sk_proto, 0);
-	if (err)
-		goto out;
-	err = register_pppox_proto(PX_PROTO_OL2TP, &pppol2tp_proto);
-	if (err)
-		goto out_unregister_pppol2tp_proto;
-
-	err = register_pernet_device(&pppol2tp_net_ops);
-	if (err)
-		goto out_unregister_pppox_proto;
-
-	printk(KERN_INFO "PPPoL2TP kernel driver, %s\n",
-	       PPPOL2TP_DRV_VERSION);
-
-out:
-	return err;
-out_unregister_pppox_proto:
-	unregister_pppox_proto(PX_PROTO_OL2TP);
-out_unregister_pppol2tp_proto:
-	proto_unregister(&pppol2tp_sk_proto);
-	goto out;
-}
-
-static void __exit pppol2tp_exit(void)
-{
-	unregister_pppox_proto(PX_PROTO_OL2TP);
-	unregister_pernet_device(&pppol2tp_net_ops);
-	proto_unregister(&pppol2tp_sk_proto);
-}
-
-module_init(pppol2tp_init);
-module_exit(pppol2tp_exit);
-
-MODULE_AUTHOR("Martijn van Oosterhout <kleptog@svana.org>, "
-	      "James Chapman <jchapman@katalix.com>");
-MODULE_DESCRIPTION("PPP over L2TP over UDP");
-MODULE_LICENSE("GPL");
-MODULE_VERSION(PPPOL2TP_DRV_VERSION);
diff --git a/net/Makefile b/net/Makefile
index a5eae27..13ca77e 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_BT)		+= bluetooth/
 obj-$(CONFIG_SUNRPC)		+= sunrpc/
 obj-$(CONFIG_AF_RXRPC)		+= rxrpc/
 obj-$(CONFIG_ATM)		+= atm/
+obj-$(CONFIG_PPPOL2TP)		+= l2tp/
 obj-$(CONFIG_DECNET)		+= decnet/
 obj-$(CONFIG_ECONET)		+= econet/
 obj-$(CONFIG_PHONET)		+= phonet/
diff --git a/net/l2tp/Makefile b/net/l2tp/Makefile
new file mode 100644
index 0000000..9af41e8
--- /dev/null
+++ b/net/l2tp/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for the L2TP.
+#
+
+obj-$(CONFIG_PPPOL2TP) += pppol2tp.o
diff --git a/net/l2tp/pppol2tp.c b/net/l2tp/pppol2tp.c
new file mode 100644
index 0000000..449a982
--- /dev/null
+++ b/net/l2tp/pppol2tp.c
@@ -0,0 +1,2680 @@
+/*****************************************************************************
+ * Linux PPP over L2TP (PPPoX/PPPoL2TP) Sockets
+ *
+ * PPPoX    --- Generic PPP encapsulation socket family
+ * PPPoL2TP --- PPP over L2TP (RFC 2661)
+ *
+ * Version:	1.0.0
+ *
+ * Authors:	Martijn van Oosterhout <kleptog@svana.org>
+ *		James Chapman (jchapman@katalix.com)
+ * Contributors:
+ *		Michal Ostrowski <mostrows@speakeasy.net>
+ *		Arnaldo Carvalho de Melo <acme@xconectiva.com.br>
+ *		David S. Miller (davem@redhat.com)
+ *
+ * License:
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ *
+ */
+
+/* This driver handles only L2TP data frames; control frames are handled by a
+ * userspace application.
+ *
+ * To send data in an L2TP session, userspace opens a PPPoL2TP socket and
+ * attaches it to a bound UDP socket with local tunnel_id / session_id and
+ * peer tunnel_id / session_id set. Data can then be sent or received using
+ * regular socket sendmsg() / recvmsg() calls. Kernel parameters of the socket
+ * can be read or modified using ioctl() or [gs]etsockopt() calls.
+ *
+ * When a PPPoL2TP socket is connected with local and peer session_id values
+ * zero, the socket is treated as a special tunnel management socket.
+ *
+ * Here's example userspace code to create a socket for sending/receiving data
+ * over an L2TP session:-
+ *
+ *	struct sockaddr_pppol2tp sax;
+ *	int fd;
+ *	int session_fd;
+ *
+ *	fd = socket(AF_PPPOX, SOCK_DGRAM, PX_PROTO_OL2TP);
+ *
+ *	sax.sa_family = AF_PPPOX;
+ *	sax.sa_protocol = PX_PROTO_OL2TP;
+ *	sax.pppol2tp.fd = tunnel_fd;	// bound UDP socket
+ *	sax.pppol2tp.addr.sin_addr.s_addr = addr->sin_addr.s_addr;
+ *	sax.pppol2tp.addr.sin_port = addr->sin_port;
+ *	sax.pppol2tp.addr.sin_family = AF_INET;
+ *	sax.pppol2tp.s_tunnel  = tunnel_id;
+ *	sax.pppol2tp.s_session = session_id;
+ *	sax.pppol2tp.d_tunnel  = peer_tunnel_id;
+ *	sax.pppol2tp.d_session = peer_session_id;
+ *
+ *	session_fd = connect(fd, (struct sockaddr *)&sax, sizeof(sax));
+ *
+ * A pppd plugin that allows PPP traffic to be carried over L2TP using
+ * this driver is available from the OpenL2TP project at
+ * http://openl2tp.sourceforge.net.
+ */
+
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/list.h>
+#include <asm/uaccess.h>
+
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/kthread.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/jiffies.h>
+
+#include <linux/netdevice.h>
+#include <linux/net.h>
+#include <linux/inetdevice.h>
+#include <linux/skbuff.h>
+#include <linux/init.h>
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <linux/if_pppox.h>
+#include <linux/if_pppol2tp.h>
+#include <net/sock.h>
+#include <linux/ppp_channel.h>
+#include <linux/ppp_defs.h>
+#include <linux/if_ppp.h>
+#include <linux/file.h>
+#include <linux/hash.h>
+#include <linux/sort.h>
+#include <linux/proc_fs.h>
+#include <linux/nsproxy.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include <net/dst.h>
+#include <net/ip.h>
+#include <net/udp.h>
+#include <net/xfrm.h>
+
+#include <asm/byteorder.h>
+#include <asm/atomic.h>
+
+
+#define PPPOL2TP_DRV_VERSION	"V1.0"
+
+/* L2TP header constants */
+#define L2TP_HDRFLAG_T	   0x8000
+#define L2TP_HDRFLAG_L	   0x4000
+#define L2TP_HDRFLAG_S	   0x0800
+#define L2TP_HDRFLAG_O	   0x0200
+#define L2TP_HDRFLAG_P	   0x0100
+
+#define L2TP_HDR_VER_MASK  0x000F
+#define L2TP_HDR_VER	   0x0002
+
+/* Space for UDP, L2TP and PPP headers */
+#define PPPOL2TP_HEADER_OVERHEAD	40
+
+/* Just some random numbers */
+#define L2TP_TUNNEL_MAGIC	0x42114DDA
+#define L2TP_SESSION_MAGIC	0x0C04EB7D
+
+#define PPPOL2TP_HASH_BITS	4
+#define PPPOL2TP_HASH_SIZE	(1 << PPPOL2TP_HASH_BITS)
+
+/* Default trace flags */
+#define PPPOL2TP_DEFAULT_DEBUG_FLAGS	0
+
+#define PRINTK(_mask, _type, _lvl, _fmt, args...)			\
+	do {								\
+		if ((_mask) & (_type))					\
+			printk(_lvl "PPPOL2TP: " _fmt, ##args);		\
+	} while(0)
+
+/* Number of bytes to build transmit L2TP headers.
+ * Unfortunately the size is different depending on whether sequence numbers
+ * are enabled.
+ */
+#define PPPOL2TP_L2TP_HDR_SIZE_SEQ		10
+#define PPPOL2TP_L2TP_HDR_SIZE_NOSEQ		6
+
+struct pppol2tp_tunnel;
+
+/* Describes a session. It is the sk_user_data field in the PPPoL2TP
+ * socket. Contains information to determine incoming packets and transmit
+ * outgoing ones.
+ */
+struct pppol2tp_session
+{
+	int			magic;		/* should be
+						 * L2TP_SESSION_MAGIC */
+	int			owner;		/* pid that opened the socket */
+
+	struct sock		*sock;		/* Pointer to the session
+						 * PPPoX socket */
+	struct sock		*tunnel_sock;	/* Pointer to the tunnel UDP
+						 * socket */
+
+	struct pppol2tp_addr	tunnel_addr;	/* Description of tunnel */
+
+	struct pppol2tp_tunnel	*tunnel;	/* back pointer to tunnel
+						 * context */
+
+	char			name[20];	/* "sess xxxxx/yyyyy", where
+						 * x=tunnel_id, y=session_id */
+	int			mtu;
+	int			mru;
+	int			flags;		/* accessed by PPPIOCGFLAGS.
+						 * Unused. */
+	unsigned		recv_seq:1;	/* expect receive packets with
+						 * sequence numbers? */
+	unsigned		send_seq:1;	/* send packets with sequence
+						 * numbers? */
+	unsigned		lns_mode:1;	/* behave as LNS? LAC enables
+						 * sequence numbers under
+						 * control of LNS. */
+	int			debug;		/* bitmask of debug message
+						 * categories */
+	int			reorder_timeout; /* configured reorder timeout
+						  * (in jiffies) */
+	u16			nr;		/* session NR state (receive) */
+	u16			ns;		/* session NR state (send) */
+	struct sk_buff_head	reorder_q;	/* receive reorder queue */
+	struct pppol2tp_ioc_stats stats;
+	struct hlist_node	hlist;		/* Hash list node */
+};
+
+/* The sk_user_data field of the tunnel's UDP socket. It contains info to track
+ * all the associated sessions so incoming packets can be sorted out
+ */
+struct pppol2tp_tunnel
+{
+	int			magic;		/* Should be L2TP_TUNNEL_MAGIC */
+	rwlock_t		hlist_lock;	/* protect session_hlist */
+	struct hlist_head	session_hlist[PPPOL2TP_HASH_SIZE];
+						/* hashed list of sessions,
+						 * hashed by id */
+	int			debug;		/* bitmask of debug message
+						 * categories */
+	char			name[12];	/* "tunl xxxxx" */
+	struct pppol2tp_ioc_stats stats;
+
+	void (*old_sk_destruct)(struct sock *);
+
+	struct sock		*sock;		/* Parent socket */
+	struct list_head	list;		/* Keep a list of all open
+						 * prepared sockets */
+	struct net		*pppol2tp_net;	/* the net we belong to */
+
+	atomic_t		ref_count;
+};
+
+/* Private data stored for received packets in the skb.
+ */
+struct pppol2tp_skb_cb {
+	u16			ns;
+	u16			nr;
+	u16			has_seq;
+	u16			length;
+	unsigned long		expires;
+};
+
+#define PPPOL2TP_SKB_CB(skb)	((struct pppol2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
+
+static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb);
+static void pppol2tp_tunnel_free(struct pppol2tp_tunnel *tunnel);
+
+static atomic_t pppol2tp_tunnel_count;
+static atomic_t pppol2tp_session_count;
+static struct ppp_channel_ops pppol2tp_chan_ops = { pppol2tp_xmit , NULL };
+static const struct proto_ops pppol2tp_ops;
+
+/* per-net private data for this module */
+static int pppol2tp_net_id __read_mostly;
+struct pppol2tp_net {
+	struct list_head pppol2tp_tunnel_list;
+	rwlock_t pppol2tp_tunnel_list_lock;
+};
+
+static inline struct pppol2tp_net *pppol2tp_pernet(struct net *net)
+{
+	BUG_ON(!net);
+
+	return net_generic(net, pppol2tp_net_id);
+}
+
+/* Helpers to obtain tunnel/session contexts from sockets.
+ */
+static inline struct pppol2tp_session *pppol2tp_sock_to_session(struct sock *sk)
+{
+	struct pppol2tp_session *session;
+
+	if (sk == NULL)
+		return NULL;
+
+	sock_hold(sk);
+	session = (struct pppol2tp_session *)(sk->sk_user_data);
+	if (session == NULL) {
+		sock_put(sk);
+		goto out;
+	}
+
+	BUG_ON(session->magic != L2TP_SESSION_MAGIC);
+out:
+	return session;
+}
+
+static inline struct pppol2tp_tunnel *pppol2tp_sock_to_tunnel(struct sock *sk)
+{
+	struct pppol2tp_tunnel *tunnel;
+
+	if (sk == NULL)
+		return NULL;
+
+	sock_hold(sk);
+	tunnel = (struct pppol2tp_tunnel *)(sk->sk_user_data);
+	if (tunnel == NULL) {
+		sock_put(sk);
+		goto out;
+	}
+
+	BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
+out:
+	return tunnel;
+}
+
+/* Tunnel reference counts. Incremented per session that is added to
+ * the tunnel.
+ */
+static inline void pppol2tp_tunnel_inc_refcount(struct pppol2tp_tunnel *tunnel)
+{
+	atomic_inc(&tunnel->ref_count);
+}
+
+static inline void pppol2tp_tunnel_dec_refcount(struct pppol2tp_tunnel *tunnel)
+{
+	if (atomic_dec_and_test(&tunnel->ref_count))
+		pppol2tp_tunnel_free(tunnel);
+}
+
+/* Session hash list.
+ * The session_id SHOULD be random according to RFC2661, but several
+ * L2TP implementations (Cisco and Microsoft) use incrementing
+ * session_ids.  So we do a real hash on the session_id, rather than a
+ * simple bitmask.
+ */
+static inline struct hlist_head *
+pppol2tp_session_id_hash(struct pppol2tp_tunnel *tunnel, u16 session_id)
+{
+	unsigned long hash_val = (unsigned long) session_id;
+	return &tunnel->session_hlist[hash_long(hash_val, PPPOL2TP_HASH_BITS)];
+}
+
+/* Lookup a session by id
+ */
+static struct pppol2tp_session *
+pppol2tp_session_find(struct pppol2tp_tunnel *tunnel, u16 session_id)
+{
+	struct hlist_head *session_list =
+		pppol2tp_session_id_hash(tunnel, session_id);
+	struct pppol2tp_session *session;
+	struct hlist_node *walk;
+
+	read_lock_bh(&tunnel->hlist_lock);
+	hlist_for_each_entry(session, walk, session_list, hlist) {
+		if (session->tunnel_addr.s_session == session_id) {
+			read_unlock_bh(&tunnel->hlist_lock);
+			return session;
+		}
+	}
+	read_unlock_bh(&tunnel->hlist_lock);
+
+	return NULL;
+}
+
+/* Lookup a tunnel by id
+ */
+static struct pppol2tp_tunnel *pppol2tp_tunnel_find(struct net *net, u16 tunnel_id)
+{
+	struct pppol2tp_tunnel *tunnel;
+	struct pppol2tp_net *pn = pppol2tp_pernet(net);
+
+	read_lock_bh(&pn->pppol2tp_tunnel_list_lock);
+	list_for_each_entry(tunnel, &pn->pppol2tp_tunnel_list, list) {
+		if (tunnel->stats.tunnel_id == tunnel_id) {
+			read_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
+			return tunnel;
+		}
+	}
+	read_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
+
+	return NULL;
+}
+
+/*****************************************************************************
+ * Receive data handling
+ *****************************************************************************/
+
+/* Queue a skb in order. We come here only if the skb has an L2TP sequence
+ * number.
+ */
+static void pppol2tp_recv_queue_skb(struct pppol2tp_session *session, struct sk_buff *skb)
+{
+	struct sk_buff *skbp;
+	struct sk_buff *tmp;
+	u16 ns = PPPOL2TP_SKB_CB(skb)->ns;
+
+	spin_lock_bh(&session->reorder_q.lock);
+	skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
+		if (PPPOL2TP_SKB_CB(skbp)->ns > ns) {
+			__skb_queue_before(&session->reorder_q, skbp, skb);
+			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
+			       "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
+			       session->name, ns, PPPOL2TP_SKB_CB(skbp)->ns,
+			       skb_queue_len(&session->reorder_q));
+			session->stats.rx_oos_packets++;
+			goto out;
+		}
+	}
+
+	__skb_queue_tail(&session->reorder_q, skb);
+
+out:
+	spin_unlock_bh(&session->reorder_q.lock);
+}
+
+/* Dequeue a single skb.
+ */
+static void pppol2tp_recv_dequeue_skb(struct pppol2tp_session *session, struct sk_buff *skb)
+{
+	struct pppol2tp_tunnel *tunnel = session->tunnel;
+	int length = PPPOL2TP_SKB_CB(skb)->length;
+	struct sock *session_sock = NULL;
+
+	/* We're about to requeue the skb, so return resources
+	 * to its current owner (a socket receive buffer).
+	 */
+	skb_orphan(skb);
+
+	tunnel->stats.rx_packets++;
+	tunnel->stats.rx_bytes += length;
+	session->stats.rx_packets++;
+	session->stats.rx_bytes += length;
+
+	if (PPPOL2TP_SKB_CB(skb)->has_seq) {
+		/* Bump our Nr */
+		session->nr++;
+		PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
+		       "%s: updated nr to %hu\n", session->name, session->nr);
+	}
+
+	/* If the socket is bound, send it in to PPP's input queue. Otherwise
+	 * queue it on the session socket.
+	 */
+	session_sock = session->sock;
+	if (session_sock->sk_state & PPPOX_BOUND) {
+		struct pppox_sock *po;
+		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
+		       "%s: recv %d byte data frame, passing to ppp\n",
+		       session->name, length);
+
+		/* We need to forget all info related to the L2TP packet
+		 * gathered in the skb as we are going to reuse the same
+		 * skb for the inner packet.
+		 * Namely we need to:
+		 * - reset xfrm (IPSec) information as it applies to
+		 *   the outer L2TP packet and not to the inner one
+		 * - release the dst to force a route lookup on the inner
+		 *   IP packet since skb->dst currently points to the dst
+		 *   of the UDP tunnel
+		 * - reset netfilter information as it doesn't apply
+		 *   to the inner packet either
+		 */
+		secpath_reset(skb);
+		skb_dst_drop(skb);
+		nf_reset(skb);
+
+		po = pppox_sk(session_sock);
+		ppp_input(&po->chan, skb);
+	} else {
+		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_INFO,
+		       "%s: socket not bound\n", session->name);
+
+		/* Not bound. Nothing we can do, so discard. */
+		session->stats.rx_errors++;
+		kfree_skb(skb);
+	}
+
+	sock_put(session->sock);
+}
+
+/* Dequeue skbs from the session's reorder_q, subject to packet order.
+ * Skbs that have been in the queue for too long are simply discarded.
+ */
+static void pppol2tp_recv_dequeue(struct pppol2tp_session *session)
+{
+	struct sk_buff *skb;
+	struct sk_buff *tmp;
+
+	/* If the pkt at the head of the queue has the nr that we
+	 * expect to send up next, dequeue it and any other
+	 * in-sequence packets behind it.
+	 */
+	spin_lock_bh(&session->reorder_q.lock);
+	skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
+		if (time_after(jiffies, PPPOL2TP_SKB_CB(skb)->expires)) {
+			session->stats.rx_seq_discards++;
+			session->stats.rx_errors++;
+			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
+			       "%s: oos pkt %hu len %d discarded (too old), "
+			       "waiting for %hu, reorder_q_len=%d\n",
+			       session->name, PPPOL2TP_SKB_CB(skb)->ns,
+			       PPPOL2TP_SKB_CB(skb)->length, session->nr,
+			       skb_queue_len(&session->reorder_q));
+			__skb_unlink(skb, &session->reorder_q);
+			kfree_skb(skb);
+			sock_put(session->sock);
+			continue;
+		}
+
+		if (PPPOL2TP_SKB_CB(skb)->has_seq) {
+			if (PPPOL2TP_SKB_CB(skb)->ns != session->nr) {
+				PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
+				       "%s: holding oos pkt %hu len %d, "
+				       "waiting for %hu, reorder_q_len=%d\n",
+				       session->name, PPPOL2TP_SKB_CB(skb)->ns,
+				       PPPOL2TP_SKB_CB(skb)->length, session->nr,
+				       skb_queue_len(&session->reorder_q));
+				goto out;
+			}
+		}
+		__skb_unlink(skb, &session->reorder_q);
+
+		/* Process the skb. We release the queue lock while we
+		 * do so to let other contexts process the queue.
+		 */
+		spin_unlock_bh(&session->reorder_q.lock);
+		pppol2tp_recv_dequeue_skb(session, skb);
+		spin_lock_bh(&session->reorder_q.lock);
+	}
+
+out:
+	spin_unlock_bh(&session->reorder_q.lock);
+}
+
+static inline int pppol2tp_verify_udp_checksum(struct sock *sk,
+					       struct sk_buff *skb)
+{
+	struct udphdr *uh = udp_hdr(skb);
+	u16 ulen = ntohs(uh->len);
+	struct inet_sock *inet;
+	__wsum psum;
+
+	if (sk->sk_no_check || skb_csum_unnecessary(skb) || !uh->check)
+		return 0;
+
+	inet = inet_sk(sk);
+	psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, ulen,
+				  IPPROTO_UDP, 0);
+
+	if ((skb->ip_summed == CHECKSUM_COMPLETE) &&
+	    !csum_fold(csum_add(psum, skb->csum)))
+		return 0;
+
+	skb->csum = psum;
+
+	return __skb_checksum_complete(skb);
+}
+
+/* Internal receive frame. Do the real work of receiving an L2TP data frame
+ * here. The skb is not on a list when we get here.
+ * Returns 0 if the packet was a data packet and was successfully passed on.
+ * Returns 1 if the packet was not a good data packet and could not be
+ * forwarded.  All such packets are passed up to userspace to deal with.
+ */
+static int pppol2tp_recv_core(struct sock *sock, struct sk_buff *skb)
+{
+	struct pppol2tp_session *session = NULL;
+	struct pppol2tp_tunnel *tunnel;
+	unsigned char *ptr, *optr;
+	u16 hdrflags;
+	u16 tunnel_id, session_id;
+	int length;
+	int offset;
+
+	tunnel = pppol2tp_sock_to_tunnel(sock);
+	if (tunnel == NULL)
+		goto no_tunnel;
+
+	if (tunnel->sock && pppol2tp_verify_udp_checksum(tunnel->sock, skb))
+		goto discard_bad_csum;
+
+	/* UDP always verifies the packet length. */
+	__skb_pull(skb, sizeof(struct udphdr));
+
+	/* Short packet? */
+	if (!pskb_may_pull(skb, 12)) {
+		PRINTK(tunnel->debug, PPPOL2TP_MSG_DATA, KERN_INFO,
+		       "%s: recv short packet (len=%d)\n", tunnel->name, skb->len);
+		goto error;
+	}
+
+	/* Point to L2TP header */
+	optr = ptr = skb->data;
+
+	/* Get L2TP header flags */
+	hdrflags = ntohs(*(__be16*)ptr);
+
+	/* Trace packet contents, if enabled */
+	if (tunnel->debug & PPPOL2TP_MSG_DATA) {
+		length = min(16u, skb->len);
+		if (!pskb_may_pull(skb, length))
+			goto error;
+
+		printk(KERN_DEBUG "%s: recv: ", tunnel->name);
+
+		offset = 0;
+		do {
+			printk(" %02X", ptr[offset]);
+		} while (++offset < length);
+
+		printk("\n");
+	}
+
+	/* Get length of L2TP packet */
+	length = skb->len;
+
+	/* If type is control packet, it is handled by userspace. */
+	if (hdrflags & L2TP_HDRFLAG_T) {
+		PRINTK(tunnel->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
+		       "%s: recv control packet, len=%d\n", tunnel->name, length);
+		goto error;
+	}
+
+	/* Skip flags */
+	ptr += 2;
+
+	/* If length is present, skip it */
+	if (hdrflags & L2TP_HDRFLAG_L)
+		ptr += 2;
+
+	/* Extract tunnel and session ID */
+	tunnel_id = ntohs(*(__be16 *) ptr);
+	ptr += 2;
+	session_id = ntohs(*(__be16 *) ptr);
+	ptr += 2;
+
+	/* Find the session context */
+	session = pppol2tp_session_find(tunnel, session_id);
+	if (!session) {
+		/* Not found? Pass to userspace to deal with */
+		PRINTK(tunnel->debug, PPPOL2TP_MSG_DATA, KERN_INFO,
+		       "%s: no socket found (%hu/%hu). Passing up.\n",
+		       tunnel->name, tunnel_id, session_id);
+		goto error;
+	}
+	sock_hold(session->sock);
+
+	/* The ref count on the socket was increased by the above call since
+	 * we now hold a pointer to the session. Take care to do sock_put()
+	 * when exiting this function from now on...
+	 */
+
+	/* Handle the optional sequence numbers.  If we are the LAC,
+	 * enable/disable sequence numbers under the control of the LNS.  If
+	 * no sequence numbers present but we were expecting them, discard
+	 * frame.
+	 */
+	if (hdrflags & L2TP_HDRFLAG_S) {
+		u16 ns, nr;
+		ns = ntohs(*(__be16 *) ptr);
+		ptr += 2;
+		nr = ntohs(*(__be16 *) ptr);
+		ptr += 2;
+
+		/* Received a packet with sequence numbers. If we're the LNS,
+		 * check if we sre sending sequence numbers and if not,
+		 * configure it so.
+		 */
+		if ((!session->lns_mode) && (!session->send_seq)) {
+			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_INFO,
+			       "%s: requested to enable seq numbers by LNS\n",
+			       session->name);
+			session->send_seq = -1;
+		}
+
+		/* Store L2TP info in the skb */
+		PPPOL2TP_SKB_CB(skb)->ns = ns;
+		PPPOL2TP_SKB_CB(skb)->nr = nr;
+		PPPOL2TP_SKB_CB(skb)->has_seq = 1;
+
+		PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
+		       "%s: recv data ns=%hu, nr=%hu, session nr=%hu\n",
+		       session->name, ns, nr, session->nr);
+	} else {
+		/* No sequence numbers.
+		 * If user has configured mandatory sequence numbers, discard.
+		 */
+		if (session->recv_seq) {
+			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_WARNING,
+			       "%s: recv data has no seq numbers when required. "
+			       "Discarding\n", session->name);
+			session->stats.rx_seq_discards++;
+			goto discard;
+		}
+
+		/* If we're the LAC and we're sending sequence numbers, the
+		 * LNS has requested that we no longer send sequence numbers.
+		 * If we're the LNS and we're sending sequence numbers, the
+		 * LAC is broken. Discard the frame.
+		 */
+		if ((!session->lns_mode) && (session->send_seq)) {
+			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_INFO,
+			       "%s: requested to disable seq numbers by LNS\n",
+			       session->name);
+			session->send_seq = 0;
+		} else if (session->send_seq) {
+			PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_WARNING,
+			       "%s: recv data has no seq numbers when required. "
+			       "Discarding\n", session->name);
+			session->stats.rx_seq_discards++;
+			goto discard;
+		}
+
+		/* Store L2TP info in the skb */
+		PPPOL2TP_SKB_CB(skb)->has_seq = 0;
+	}
+
+	/* If offset bit set, skip it. */
+	if (hdrflags & L2TP_HDRFLAG_O) {
+		offset = ntohs(*(__be16 *)ptr);
+		ptr += 2 + offset;
+	}
+
+	offset = ptr - optr;
+	if (!pskb_may_pull(skb, offset))
+		goto discard;
+
+	__skb_pull(skb, offset);
+
+	/* Skip PPP header, if present.	 In testing, Microsoft L2TP clients
+	 * don't send the PPP header (PPP header compression enabled), but
+	 * other clients can include the header. So we cope with both cases
+	 * here. The PPP header is always FF03 when using L2TP.
+	 *
+	 * Note that skb->data[] isn't dereferenced from a u16 ptr here since
+	 * the field may be unaligned.
+	 */
+	if (!pskb_may_pull(skb, 2))
+		goto discard;
+
+	if ((skb->data[0] == 0xff) && (skb->data[1] == 0x03))
+		skb_pull(skb, 2);
+
+	/* Prepare skb for adding to the session's reorder_q.  Hold
+	 * packets for max reorder_timeout or 1 second if not
+	 * reordering.
+	 */
+	PPPOL2TP_SKB_CB(skb)->length = length;
+	PPPOL2TP_SKB_CB(skb)->expires = jiffies +
+		(session->reorder_timeout ? session->reorder_timeout : HZ);
+
+	/* Add packet to the session's receive queue. Reordering is done here, if
+	 * enabled. Saved L2TP protocol info is stored in skb->sb[].
+	 */
+	if (PPPOL2TP_SKB_CB(skb)->has_seq) {
+		if (session->reorder_timeout != 0) {
+			/* Packet reordering enabled. Add skb to session's
+			 * reorder queue, in order of ns.
+			 */
+			pppol2tp_recv_queue_skb(session, skb);
+		} else {
+			/* Packet reordering disabled. Discard out-of-sequence
+			 * packets
+			 */
+			if (PPPOL2TP_SKB_CB(skb)->ns != session->nr) {
+				session->stats.rx_seq_discards++;
+				PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
+				       "%s: oos pkt %hu len %d discarded, "
+				       "waiting for %hu, reorder_q_len=%d\n",
+				       session->name, PPPOL2TP_SKB_CB(skb)->ns,
+				       PPPOL2TP_SKB_CB(skb)->length, session->nr,
+				       skb_queue_len(&session->reorder_q));
+				goto discard;
+			}
+			skb_queue_tail(&session->reorder_q, skb);
+		}
+	} else {
+		/* No sequence numbers. Add the skb to the tail of the
+		 * reorder queue. This ensures that it will be
+		 * delivered after all previous sequenced skbs.
+		 */
+		skb_queue_tail(&session->reorder_q, skb);
+	}
+
+	/* Try to dequeue as many skbs from reorder_q as we can. */
+	pppol2tp_recv_dequeue(session);
+	sock_put(sock);
+
+	return 0;
+
+discard:
+	session->stats.rx_errors++;
+	kfree_skb(skb);
+	sock_put(session->sock);
+	sock_put(sock);
+
+	return 0;
+
+discard_bad_csum:
+	LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
+	UDP_INC_STATS_USER(&init_net, UDP_MIB_INERRORS, 0);
+	tunnel->stats.rx_errors++;
+	kfree_skb(skb);
+	sock_put(sock);
+
+	return 0;
+
+error:
+	/* Put UDP header back */
+	__skb_push(skb, sizeof(struct udphdr));
+	sock_put(sock);
+
+no_tunnel:
+	return 1;
+}
+
+/* UDP encapsulation receive handler. See net/ipv4/udp.c.
+ * Return codes:
+ * 0 : success.
+ * <0: error
+ * >0: skb should be passed up to userspace as UDP.
+ */
+static int pppol2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
+{
+	struct pppol2tp_tunnel *tunnel;
+
+	tunnel = pppol2tp_sock_to_tunnel(sk);
+	if (tunnel == NULL)
+		goto pass_up;
+
+	PRINTK(tunnel->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
+	       "%s: received %d bytes\n", tunnel->name, skb->len);
+
+	if (pppol2tp_recv_core(sk, skb))
+		goto pass_up_put;
+
+	sock_put(sk);
+	return 0;
+
+pass_up_put:
+	sock_put(sk);
+pass_up:
+	return 1;
+}
+
+/* Receive message. This is the recvmsg for the PPPoL2TP socket.
+ */
+static int pppol2tp_recvmsg(struct kiocb *iocb, struct socket *sock,
+			    struct msghdr *msg, size_t len,
+			    int flags)
+{
+	int err;
+	struct sk_buff *skb;
+	struct sock *sk = sock->sk;
+
+	err = -EIO;
+	if (sk->sk_state & PPPOX_BOUND)
+		goto end;
+
+	msg->msg_namelen = 0;
+
+	err = 0;
+	skb = skb_recv_datagram(sk, flags & ~MSG_DONTWAIT,
+				flags & MSG_DONTWAIT, &err);
+	if (!skb)
+		goto end;
+
+	if (len > skb->len)
+		len = skb->len;
+	else if (len < skb->len)
+		msg->msg_flags |= MSG_TRUNC;
+
+	err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, len);
+	if (likely(err == 0))
+		err = len;
+
+	kfree_skb(skb);
+end:
+	return err;
+}
+
+/************************************************************************
+ * Transmit handling
+ ***********************************************************************/
+
+/* Tell how big L2TP headers are for a particular session. This
+ * depends on whether sequence numbers are being used.
+ */
+static inline int pppol2tp_l2tp_header_len(struct pppol2tp_session *session)
+{
+	if (session->send_seq)
+		return PPPOL2TP_L2TP_HDR_SIZE_SEQ;
+
+	return PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
+}
+
+/* Build an L2TP header for the session into the buffer provided.
+ */
+static void pppol2tp_build_l2tp_header(struct pppol2tp_session *session,
+				       void *buf)
+{
+	__be16 *bufp = buf;
+	u16 flags = L2TP_HDR_VER;
+
+	if (session->send_seq)
+		flags |= L2TP_HDRFLAG_S;
+
+	/* Setup L2TP header.
+	 * FIXME: Can this ever be unaligned? Is direct dereferencing of
+	 * 16-bit header fields safe here for all architectures?
+	 */
+	*bufp++ = htons(flags);
+	*bufp++ = htons(session->tunnel_addr.d_tunnel);
+	*bufp++ = htons(session->tunnel_addr.d_session);
+	if (session->send_seq) {
+		*bufp++ = htons(session->ns);
+		*bufp++ = 0;
+		session->ns++;
+		PRINTK(session->debug, PPPOL2TP_MSG_SEQ, KERN_DEBUG,
+		       "%s: updated ns to %hu\n", session->name, session->ns);
+	}
+}
+
+/* This is the sendmsg for the PPPoL2TP pppol2tp_session socket.  We come here
+ * when a user application does a sendmsg() on the session socket. L2TP and
+ * PPP headers must be inserted into the user's data.
+ */
+static int pppol2tp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *m,
+			    size_t total_len)
+{
+	static const unsigned char ppph[2] = { 0xff, 0x03 };
+	struct sock *sk = sock->sk;
+	struct inet_sock *inet;
+	__wsum csum;
+	struct sk_buff *skb;
+	int error;
+	int hdr_len;
+	struct pppol2tp_session *session;
+	struct pppol2tp_tunnel *tunnel;
+	struct udphdr *uh;
+	unsigned int len;
+	struct sock *sk_tun;
+	u16 udp_len;
+
+	error = -ENOTCONN;
+	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED))
+		goto error;
+
+	/* Get session and tunnel contexts */
+	error = -EBADF;
+	session = pppol2tp_sock_to_session(sk);
+	if (session == NULL)
+		goto error;
+
+	sk_tun = session->tunnel_sock;
+	tunnel = pppol2tp_sock_to_tunnel(sk_tun);
+	if (tunnel == NULL)
+		goto error_put_sess;
+
+	/* What header length is configured for this session? */
+	hdr_len = pppol2tp_l2tp_header_len(session);
+
+	/* Allocate a socket buffer */
+	error = -ENOMEM;
+	skb = sock_wmalloc(sk, NET_SKB_PAD + sizeof(struct iphdr) +
+			   sizeof(struct udphdr) + hdr_len +
+			   sizeof(ppph) + total_len,
+			   0, GFP_KERNEL);
+	if (!skb)
+		goto error_put_sess_tun;
+
+	/* Reserve space for headers. */
+	skb_reserve(skb, NET_SKB_PAD);
+	skb_reset_network_header(skb);
+	skb_reserve(skb, sizeof(struct iphdr));
+	skb_reset_transport_header(skb);
+
+	/* Build UDP header */
+	inet = inet_sk(sk_tun);
+	udp_len = hdr_len + sizeof(ppph) + total_len;
+	uh = (struct udphdr *) skb->data;
+	uh->source = inet->inet_sport;
+	uh->dest = inet->inet_dport;
+	uh->len = htons(udp_len);
+	uh->check = 0;
+	skb_put(skb, sizeof(struct udphdr));
+
+	/* Build L2TP header */
+	pppol2tp_build_l2tp_header(session, skb->data);
+	skb_put(skb, hdr_len);
+
+	/* Add PPP header */
+	skb->data[0] = ppph[0];
+	skb->data[1] = ppph[1];
+	skb_put(skb, 2);
+
+	/* Copy user data into skb */
+	error = memcpy_fromiovec(skb->data, m->msg_iov, total_len);
+	if (error < 0) {
+		kfree_skb(skb);
+		goto error_put_sess_tun;
+	}
+	skb_put(skb, total_len);
+
+	/* Calculate UDP checksum if configured to do so */
+	if (sk_tun->sk_no_check == UDP_CSUM_NOXMIT)
+		skb->ip_summed = CHECKSUM_NONE;
+	else if (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM)) {
+		skb->ip_summed = CHECKSUM_COMPLETE;
+		csum = skb_checksum(skb, 0, udp_len, 0);
+		uh->check = csum_tcpudp_magic(inet->inet_saddr,
+					      inet->inet_daddr,
+					      udp_len, IPPROTO_UDP, csum);
+		if (uh->check == 0)
+			uh->check = CSUM_MANGLED_0;
+	} else {
+		skb->ip_summed = CHECKSUM_PARTIAL;
+		skb->csum_start = skb_transport_header(skb) - skb->head;
+		skb->csum_offset = offsetof(struct udphdr, check);
+		uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
+					       inet->inet_daddr,
+					       udp_len, IPPROTO_UDP, 0);
+	}
+
+	/* Debug */
+	if (session->send_seq)
+		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
+		       "%s: send %Zd bytes, ns=%hu\n", session->name,
+		       total_len, session->ns - 1);
+	else
+		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
+		       "%s: send %Zd bytes\n", session->name, total_len);
+
+	if (session->debug & PPPOL2TP_MSG_DATA) {
+		int i;
+		unsigned char *datap = skb->data;
+
+		printk(KERN_DEBUG "%s: xmit:", session->name);
+		for (i = 0; i < total_len; i++) {
+			printk(" %02X", *datap++);
+			if (i == 15) {
+				printk(" ...");
+				break;
+			}
+		}
+		printk("\n");
+	}
+
+	/* Queue the packet to IP for output */
+	len = skb->len;
+	error = ip_queue_xmit(skb, 1);
+
+	/* Update stats */
+	if (error >= 0) {
+		tunnel->stats.tx_packets++;
+		tunnel->stats.tx_bytes += len;
+		session->stats.tx_packets++;
+		session->stats.tx_bytes += len;
+	} else {
+		tunnel->stats.tx_errors++;
+		session->stats.tx_errors++;
+	}
+
+	return error;
+
+error_put_sess_tun:
+	sock_put(session->tunnel_sock);
+error_put_sess:
+	sock_put(sk);
+error:
+	return error;
+}
+
+/* Automatically called when the skb is freed.
+ */
+static void pppol2tp_sock_wfree(struct sk_buff *skb)
+{
+	sock_put(skb->sk);
+}
+
+/* For data skbs that we transmit, we associate with the tunnel socket
+ * but don't do accounting.
+ */
+static inline void pppol2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
+{
+	sock_hold(sk);
+	skb->sk = sk;
+	skb->destructor = pppol2tp_sock_wfree;
+}
+
+/* Transmit function called by generic PPP driver.  Sends PPP frame
+ * over PPPoL2TP socket.
+ *
+ * This is almost the same as pppol2tp_sendmsg(), but rather than
+ * being called with a msghdr from userspace, it is called with a skb
+ * from the kernel.
+ *
+ * The supplied skb from ppp doesn't have enough headroom for the
+ * insertion of L2TP, UDP and IP headers so we need to allocate more
+ * headroom in the skb. This will create a cloned skb. But we must be
+ * careful in the error case because the caller will expect to free
+ * the skb it supplied, not our cloned skb. So we take care to always
+ * leave the original skb unfreed if we return an error.
+ */
+static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb)
+{
+	static const u8 ppph[2] = { 0xff, 0x03 };
+	struct sock *sk = (struct sock *) chan->private;
+	struct sock *sk_tun;
+	int hdr_len;
+	u16 udp_len;
+	struct pppol2tp_session *session;
+	struct pppol2tp_tunnel *tunnel;
+	int rc;
+	int headroom;
+	int data_len = skb->len;
+	struct inet_sock *inet;
+	__wsum csum;
+	struct udphdr *uh;
+	unsigned int len;
+	int old_headroom;
+	int new_headroom;
+
+	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED))
+		goto abort;
+
+	/* Get session and tunnel contexts from the socket */
+	session = pppol2tp_sock_to_session(sk);
+	if (session == NULL)
+		goto abort;
+
+	sk_tun = session->tunnel_sock;
+	if (sk_tun == NULL)
+		goto abort_put_sess;
+	tunnel = pppol2tp_sock_to_tunnel(sk_tun);
+	if (tunnel == NULL)
+		goto abort_put_sess;
+
+	/* What header length is configured for this session? */
+	hdr_len = pppol2tp_l2tp_header_len(session);
+
+	/* Check that there's enough headroom in the skb to insert IP,
+	 * UDP and L2TP and PPP headers. If not enough, expand it to
+	 * make room. Adjust truesize.
+	 */
+	headroom = NET_SKB_PAD + sizeof(struct iphdr) +
+		sizeof(struct udphdr) + hdr_len + sizeof(ppph);
+	old_headroom = skb_headroom(skb);
+	if (skb_cow_head(skb, headroom))
+		goto abort_put_sess_tun;
+
+	new_headroom = skb_headroom(skb);
+	skb_orphan(skb);
+	skb->truesize += new_headroom - old_headroom;
+
+	/* Setup PPP header */
+	__skb_push(skb, sizeof(ppph));
+	skb->data[0] = ppph[0];
+	skb->data[1] = ppph[1];
+
+	/* Setup L2TP header */
+	pppol2tp_build_l2tp_header(session, __skb_push(skb, hdr_len));
+
+	udp_len = sizeof(struct udphdr) + hdr_len + sizeof(ppph) + data_len;
+
+	/* Setup UDP header */
+	inet = inet_sk(sk_tun);
+	__skb_push(skb, sizeof(*uh));
+	skb_reset_transport_header(skb);
+	uh = udp_hdr(skb);
+	uh->source = inet->inet_sport;
+	uh->dest = inet->inet_dport;
+	uh->len = htons(udp_len);
+	uh->check = 0;
+
+	/* Debug */
+	if (session->send_seq)
+		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
+		       "%s: send %d bytes, ns=%hu\n", session->name,
+		       data_len, session->ns - 1);
+	else
+		PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_DEBUG,
+		       "%s: send %d bytes\n", session->name, data_len);
+
+	if (session->debug & PPPOL2TP_MSG_DATA) {
+		int i;
+		unsigned char *datap = skb->data;
+
+		printk(KERN_DEBUG "%s: xmit:", session->name);
+		for (i = 0; i < data_len; i++) {
+			printk(" %02X", *datap++);
+			if (i == 31) {
+				printk(" ...");
+				break;
+			}
+		}
+		printk("\n");
+	}
+
+	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
+	IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
+			      IPSKB_REROUTED);
+	nf_reset(skb);
+
+	/* Get routing info from the tunnel socket */
+	skb_dst_drop(skb);
+	skb_dst_set(skb, dst_clone(__sk_dst_get(sk_tun)));
+	pppol2tp_skb_set_owner_w(skb, sk_tun);
+
+	/* Calculate UDP checksum if configured to do so */
+	if (sk_tun->sk_no_check == UDP_CSUM_NOXMIT)
+		skb->ip_summed = CHECKSUM_NONE;
+	else if ((skb_dst(skb) && skb_dst(skb)->dev) &&
+		 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) {
+		skb->ip_summed = CHECKSUM_COMPLETE;
+		csum = skb_checksum(skb, 0, udp_len, 0);
+		uh->check = csum_tcpudp_magic(inet->inet_saddr,
+					      inet->inet_daddr,
+					      udp_len, IPPROTO_UDP, csum);
+		if (uh->check == 0)
+			uh->check = CSUM_MANGLED_0;
+	} else {
+		skb->ip_summed = CHECKSUM_PARTIAL;
+		skb->csum_start = skb_transport_header(skb) - skb->head;
+		skb->csum_offset = offsetof(struct udphdr, check);
+		uh->check = ~csum_tcpudp_magic(inet->inet_saddr,
+					       inet->inet_daddr,
+					       udp_len, IPPROTO_UDP, 0);
+	}
+
+	/* Queue the packet to IP for output */
+	len = skb->len;
+	rc = ip_queue_xmit(skb, 1);
+
+	/* Update stats */
+	if (rc >= 0) {
+		tunnel->stats.tx_packets++;
+		tunnel->stats.tx_bytes += len;
+		session->stats.tx_packets++;
+		session->stats.tx_bytes += len;
+	} else {
+		tunnel->stats.tx_errors++;
+		session->stats.tx_errors++;
+	}
+
+	sock_put(sk_tun);
+	sock_put(sk);
+	return 1;
+
+abort_put_sess_tun:
+	sock_put(sk_tun);
+abort_put_sess:
+	sock_put(sk);
+abort:
+	/* Free the original skb */
+	kfree_skb(skb);
+	return 1;
+}
+
+/*****************************************************************************
+ * Session (and tunnel control) socket create/destroy.
+ *****************************************************************************/
+
+/* When the tunnel UDP socket is closed, all the attached sockets need to go
+ * too.
+ */
+static void pppol2tp_tunnel_closeall(struct pppol2tp_tunnel *tunnel)
+{
+	int hash;
+	struct hlist_node *walk;
+	struct hlist_node *tmp;
+	struct pppol2tp_session *session;
+	struct sock *sk;
+
+	BUG_ON(tunnel == NULL);
+
+	PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+	       "%s: closing all sessions...\n", tunnel->name);
+
+	write_lock_bh(&tunnel->hlist_lock);
+	for (hash = 0; hash < PPPOL2TP_HASH_SIZE; hash++) {
+again:
+		hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
+			struct sk_buff *skb;
+
+			session = hlist_entry(walk, struct pppol2tp_session, hlist);
+
+			sk = session->sock;
+
+			PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+			       "%s: closing session\n", session->name);
+
+			hlist_del_init(&session->hlist);
+
+			/* Since we should hold the sock lock while
+			 * doing any unbinding, we need to release the
+			 * lock we're holding before taking that lock.
+			 * Hold a reference to the sock so it doesn't
+			 * disappear as we're jumping between locks.
+			 */
+			sock_hold(sk);
+			write_unlock_bh(&tunnel->hlist_lock);
+			lock_sock(sk);
+
+			if (sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND)) {
+				pppox_unbind_sock(sk);
+				sk->sk_state = PPPOX_DEAD;
+				sk->sk_state_change(sk);
+			}
+
+			/* Purge any queued data */
+			skb_queue_purge(&sk->sk_receive_queue);
+			skb_queue_purge(&sk->sk_write_queue);
+			while ((skb = skb_dequeue(&session->reorder_q))) {
+				kfree_skb(skb);
+				sock_put(sk);
+			}
+
+			release_sock(sk);
+			sock_put(sk);
+
+			/* Now restart from the beginning of this hash
+			 * chain.  We always remove a session from the
+			 * list so we are guaranteed to make forward
+			 * progress.
+			 */
+			write_lock_bh(&tunnel->hlist_lock);
+			goto again;
+		}
+	}
+	write_unlock_bh(&tunnel->hlist_lock);
+}
+
+/* Really kill the tunnel.
+ * Come here only when all sessions have been cleared from the tunnel.
+ */
+static void pppol2tp_tunnel_free(struct pppol2tp_tunnel *tunnel)
+{
+	struct pppol2tp_net *pn = pppol2tp_pernet(tunnel->pppol2tp_net);
+
+	/* Remove from socket list */
+	write_lock_bh(&pn->pppol2tp_tunnel_list_lock);
+	list_del_init(&tunnel->list);
+	write_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
+
+	atomic_dec(&pppol2tp_tunnel_count);
+	kfree(tunnel);
+}
+
+/* Tunnel UDP socket destruct hook.
+ * The tunnel context is deleted only when all session sockets have been
+ * closed.
+ */
+static void pppol2tp_tunnel_destruct(struct sock *sk)
+{
+	struct pppol2tp_tunnel *tunnel;
+
+	tunnel = sk->sk_user_data;
+	if (tunnel == NULL)
+		goto end;
+
+	PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+	       "%s: closing...\n", tunnel->name);
+
+	/* Close all sessions */
+	pppol2tp_tunnel_closeall(tunnel);
+
+	/* No longer an encapsulation socket. See net/ipv4/udp.c */
+	(udp_sk(sk))->encap_type = 0;
+	(udp_sk(sk))->encap_rcv = NULL;
+
+	/* Remove hooks into tunnel socket */
+	tunnel->sock = NULL;
+	sk->sk_destruct = tunnel->old_sk_destruct;
+	sk->sk_user_data = NULL;
+
+	/* Call original (UDP) socket descructor */
+	if (sk->sk_destruct != NULL)
+		(*sk->sk_destruct)(sk);
+
+	pppol2tp_tunnel_dec_refcount(tunnel);
+
+end:
+	return;
+}
+
+/* Really kill the session socket. (Called from sock_put() if
+ * refcnt == 0.)
+ */
+static void pppol2tp_session_destruct(struct sock *sk)
+{
+	struct pppol2tp_session *session = NULL;
+
+	if (sk->sk_user_data != NULL) {
+		struct pppol2tp_tunnel *tunnel;
+
+		session = sk->sk_user_data;
+		if (session == NULL)
+			goto out;
+
+		BUG_ON(session->magic != L2TP_SESSION_MAGIC);
+
+		/* Don't use pppol2tp_sock_to_tunnel() here to
+		 * get the tunnel context because the tunnel
+		 * socket might have already been closed (its
+		 * sk->sk_user_data will be NULL) so use the
+		 * session's private tunnel ptr instead.
+		 */
+		tunnel = session->tunnel;
+		if (tunnel != NULL) {
+			BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
+
+			/* If session_id is zero, this is a null
+			 * session context, which was created for a
+			 * socket that is being used only to manage
+			 * tunnels.
+			 */
+			if (session->tunnel_addr.s_session != 0) {
+				/* Delete the session socket from the
+				 * hash
+				 */
+				write_lock_bh(&tunnel->hlist_lock);
+				hlist_del_init(&session->hlist);
+				write_unlock_bh(&tunnel->hlist_lock);
+
+				atomic_dec(&pppol2tp_session_count);
+			}
+
+			/* This will delete the tunnel context if this
+			 * is the last session on the tunnel.
+			 */
+			session->tunnel = NULL;
+			session->tunnel_sock = NULL;
+			pppol2tp_tunnel_dec_refcount(tunnel);
+		}
+	}
+
+	kfree(session);
+out:
+	return;
+}
+
+/* Called when the PPPoX socket (session) is closed.
+ */
+static int pppol2tp_release(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	struct pppol2tp_session *session;
+	int error;
+
+	if (!sk)
+		return 0;
+
+	error = -EBADF;
+	lock_sock(sk);
+	if (sock_flag(sk, SOCK_DEAD) != 0)
+		goto error;
+
+	pppox_unbind_sock(sk);
+
+	/* Signal the death of the socket. */
+	sk->sk_state = PPPOX_DEAD;
+	sock_orphan(sk);
+	sock->sk = NULL;
+
+	session = pppol2tp_sock_to_session(sk);
+
+	/* Purge any queued data */
+	skb_queue_purge(&sk->sk_receive_queue);
+	skb_queue_purge(&sk->sk_write_queue);
+	if (session != NULL) {
+		struct sk_buff *skb;
+		while ((skb = skb_dequeue(&session->reorder_q))) {
+			kfree_skb(skb);
+			sock_put(sk);
+		}
+		sock_put(sk);
+	}
+
+	release_sock(sk);
+
+	/* This will delete the session context via
+	 * pppol2tp_session_destruct() if the socket's refcnt drops to
+	 * zero.
+	 */
+	sock_put(sk);
+
+	return 0;
+
+error:
+	release_sock(sk);
+	return error;
+}
+
+/* Internal function to prepare a tunnel (UDP) socket to have PPPoX
+ * sockets attached to it.
+ */
+static struct sock *pppol2tp_prepare_tunnel_socket(struct net *net,
+					int fd, u16 tunnel_id, int *error)
+{
+	int err;
+	struct socket *sock = NULL;
+	struct sock *sk;
+	struct pppol2tp_tunnel *tunnel;
+	struct pppol2tp_net *pn;
+	struct sock *ret = NULL;
+
+	/* Get the tunnel UDP socket from the fd, which was opened by
+	 * the userspace L2TP daemon.
+	 */
+	err = -EBADF;
+	sock = sockfd_lookup(fd, &err);
+	if (!sock) {
+		PRINTK(-1, PPPOL2TP_MSG_CONTROL, KERN_ERR,
+		       "tunl %hu: sockfd_lookup(fd=%d) returned %d\n",
+		       tunnel_id, fd, err);
+		goto err;
+	}
+
+	sk = sock->sk;
+
+	/* Quick sanity checks */
+	err = -EPROTONOSUPPORT;
+	if (sk->sk_protocol != IPPROTO_UDP) {
+		PRINTK(-1, PPPOL2TP_MSG_CONTROL, KERN_ERR,
+		       "tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
+		       tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
+		goto err;
+	}
+	err = -EAFNOSUPPORT;
+	if (sock->ops->family != AF_INET) {
+		PRINTK(-1, PPPOL2TP_MSG_CONTROL, KERN_ERR,
+		       "tunl %hu: fd %d wrong family, got %d, expected %d\n",
+		       tunnel_id, fd, sock->ops->family, AF_INET);
+		goto err;
+	}
+
+	err = -ENOTCONN;
+
+	/* Check if this socket has already been prepped */
+	tunnel = (struct pppol2tp_tunnel *)sk->sk_user_data;
+	if (tunnel != NULL) {
+		/* User-data field already set */
+		err = -EBUSY;
+		BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
+
+		/* This socket has already been prepped */
+		ret = tunnel->sock;
+		goto out;
+	}
+
+	/* This socket is available and needs prepping. Create a new tunnel
+	 * context and init it.
+	 */
+	sk->sk_user_data = tunnel = kzalloc(sizeof(struct pppol2tp_tunnel), GFP_KERNEL);
+	if (sk->sk_user_data == NULL) {
+		err = -ENOMEM;
+		goto err;
+	}
+
+	tunnel->magic = L2TP_TUNNEL_MAGIC;
+	sprintf(&tunnel->name[0], "tunl %hu", tunnel_id);
+
+	tunnel->stats.tunnel_id = tunnel_id;
+	tunnel->debug = PPPOL2TP_DEFAULT_DEBUG_FLAGS;
+
+	/* Hook on the tunnel socket destructor so that we can cleanup
+	 * if the tunnel socket goes away.
+	 */
+	tunnel->old_sk_destruct = sk->sk_destruct;
+	sk->sk_destruct = pppol2tp_tunnel_destruct;
+
+	tunnel->sock = sk;
+	sk->sk_allocation = GFP_ATOMIC;
+
+	/* Misc init */
+	rwlock_init(&tunnel->hlist_lock);
+
+	/* The net we belong to */
+	tunnel->pppol2tp_net = net;
+	pn = pppol2tp_pernet(net);
+
+	/* Add tunnel to our list */
+	INIT_LIST_HEAD(&tunnel->list);
+	write_lock_bh(&pn->pppol2tp_tunnel_list_lock);
+	list_add(&tunnel->list, &pn->pppol2tp_tunnel_list);
+	write_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
+	atomic_inc(&pppol2tp_tunnel_count);
+
+	/* Bump the reference count. The tunnel context is deleted
+	 * only when this drops to zero.
+	 */
+	pppol2tp_tunnel_inc_refcount(tunnel);
+
+	/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
+	(udp_sk(sk))->encap_type = UDP_ENCAP_L2TPINUDP;
+	(udp_sk(sk))->encap_rcv = pppol2tp_udp_encap_recv;
+
+	ret = tunnel->sock;
+
+	*error = 0;
+out:
+	if (sock)
+		sockfd_put(sock);
+
+	return ret;
+
+err:
+	*error = err;
+	goto out;
+}
+
+static struct proto pppol2tp_sk_proto = {
+	.name	  = "PPPOL2TP",
+	.owner	  = THIS_MODULE,
+	.obj_size = sizeof(struct pppox_sock),
+};
+
+/* socket() handler. Initialize a new struct sock.
+ */
+static int pppol2tp_create(struct net *net, struct socket *sock)
+{
+	int error = -ENOMEM;
+	struct sock *sk;
+
+	sk = sk_alloc(net, PF_PPPOX, GFP_KERNEL, &pppol2tp_sk_proto);
+	if (!sk)
+		goto out;
+
+	sock_init_data(sock, sk);
+
+	sock->state  = SS_UNCONNECTED;
+	sock->ops    = &pppol2tp_ops;
+
+	sk->sk_backlog_rcv = pppol2tp_recv_core;
+	sk->sk_protocol	   = PX_PROTO_OL2TP;
+	sk->sk_family	   = PF_PPPOX;
+	sk->sk_state	   = PPPOX_NONE;
+	sk->sk_type	   = SOCK_STREAM;
+	sk->sk_destruct	   = pppol2tp_session_destruct;
+
+	error = 0;
+
+out:
+	return error;
+}
+
+/* connect() handler. Attach a PPPoX socket to a tunnel UDP socket
+ */
+static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
+			    int sockaddr_len, int flags)
+{
+	struct sock *sk = sock->sk;
+	struct sockaddr_pppol2tp *sp = (struct sockaddr_pppol2tp *) uservaddr;
+	struct pppox_sock *po = pppox_sk(sk);
+	struct sock *tunnel_sock = NULL;
+	struct pppol2tp_session *session = NULL;
+	struct pppol2tp_tunnel *tunnel;
+	struct dst_entry *dst;
+	int error = 0;
+
+	lock_sock(sk);
+
+	error = -EINVAL;
+	if (sp->sa_protocol != PX_PROTO_OL2TP)
+		goto end;
+
+	/* Check for already bound sockets */
+	error = -EBUSY;
+	if (sk->sk_state & PPPOX_CONNECTED)
+		goto end;
+
+	/* We don't supporting rebinding anyway */
+	error = -EALREADY;
+	if (sk->sk_user_data)
+		goto end; /* socket is already attached */
+
+	/* Don't bind if s_tunnel is 0 */
+	error = -EINVAL;
+	if (sp->pppol2tp.s_tunnel == 0)
+		goto end;
+
+	/* Special case: prepare tunnel socket if s_session and
+	 * d_session is 0. Otherwise look up tunnel using supplied
+	 * tunnel id.
+	 */
+	if ((sp->pppol2tp.s_session == 0) && (sp->pppol2tp.d_session == 0)) {
+		tunnel_sock = pppol2tp_prepare_tunnel_socket(sock_net(sk),
+							     sp->pppol2tp.fd,
+							     sp->pppol2tp.s_tunnel,
+							     &error);
+		if (tunnel_sock == NULL)
+			goto end;
+
+		sock_hold(tunnel_sock);
+		tunnel = tunnel_sock->sk_user_data;
+	} else {
+		tunnel = pppol2tp_tunnel_find(sock_net(sk), sp->pppol2tp.s_tunnel);
+
+		/* Error if we can't find the tunnel */
+		error = -ENOENT;
+		if (tunnel == NULL)
+			goto end;
+
+		tunnel_sock = tunnel->sock;
+	}
+
+	/* Check that this session doesn't already exist */
+	error = -EEXIST;
+	session = pppol2tp_session_find(tunnel, sp->pppol2tp.s_session);
+	if (session != NULL)
+		goto end;
+
+	/* Allocate and initialize a new session context. */
+	session = kzalloc(sizeof(struct pppol2tp_session), GFP_KERNEL);
+	if (session == NULL) {
+		error = -ENOMEM;
+		goto end;
+	}
+
+	skb_queue_head_init(&session->reorder_q);
+
+	session->magic	     = L2TP_SESSION_MAGIC;
+	session->owner	     = current->pid;
+	session->sock	     = sk;
+	session->tunnel	     = tunnel;
+	session->tunnel_sock = tunnel_sock;
+	session->tunnel_addr = sp->pppol2tp;
+	sprintf(&session->name[0], "sess %hu/%hu",
+		session->tunnel_addr.s_tunnel,
+		session->tunnel_addr.s_session);
+
+	session->stats.tunnel_id  = session->tunnel_addr.s_tunnel;
+	session->stats.session_id = session->tunnel_addr.s_session;
+
+	INIT_HLIST_NODE(&session->hlist);
+
+	/* Inherit debug options from tunnel */
+	session->debug = tunnel->debug;
+
+	/* Default MTU must allow space for UDP/L2TP/PPP
+	 * headers.
+	 */
+	session->mtu = session->mru = 1500 - PPPOL2TP_HEADER_OVERHEAD;
+
+	/* If PMTU discovery was enabled, use the MTU that was discovered */
+	dst = sk_dst_get(sk);
+	if (dst != NULL) {
+		u32 pmtu = dst_mtu(__sk_dst_get(sk));
+		if (pmtu != 0)
+			session->mtu = session->mru = pmtu -
+				PPPOL2TP_HEADER_OVERHEAD;
+		dst_release(dst);
+	}
+
+	/* Special case: if source & dest session_id == 0x0000, this socket is
+	 * being created to manage the tunnel. Don't add the session to the
+	 * session hash list, just set up the internal context for use by
+	 * ioctl() and sockopt() handlers.
+	 */
+	if ((session->tunnel_addr.s_session == 0) &&
+	    (session->tunnel_addr.d_session == 0)) {
+		error = 0;
+		sk->sk_user_data = session;
+		goto out_no_ppp;
+	}
+
+	/* Get tunnel context from the tunnel socket */
+	tunnel = pppol2tp_sock_to_tunnel(tunnel_sock);
+	if (tunnel == NULL) {
+		error = -EBADF;
+		goto end;
+	}
+
+	/* Right now, because we don't have a way to push the incoming skb's
+	 * straight through the UDP layer, the only header we need to worry
+	 * about is the L2TP header. This size is different depending on
+	 * whether sequence numbers are enabled for the data channel.
+	 */
+	po->chan.hdrlen = PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
+
+	po->chan.private = sk;
+	po->chan.ops	 = &pppol2tp_chan_ops;
+	po->chan.mtu	 = session->mtu;
+
+	error = ppp_register_net_channel(sock_net(sk), &po->chan);
+	if (error)
+		goto end_put_tun;
+
+	/* This is how we get the session context from the socket. */
+	sk->sk_user_data = session;
+
+	/* Add session to the tunnel's hash list */
+	write_lock_bh(&tunnel->hlist_lock);
+	hlist_add_head(&session->hlist,
+		       pppol2tp_session_id_hash(tunnel,
+						session->tunnel_addr.s_session));
+	write_unlock_bh(&tunnel->hlist_lock);
+
+	atomic_inc(&pppol2tp_session_count);
+
+out_no_ppp:
+	pppol2tp_tunnel_inc_refcount(tunnel);
+	sk->sk_state = PPPOX_CONNECTED;
+	PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+	       "%s: created\n", session->name);
+
+end_put_tun:
+	sock_put(tunnel_sock);
+end:
+	release_sock(sk);
+
+	if (error != 0) {
+		if (session)
+			PRINTK(session->debug,
+				PPPOL2TP_MSG_CONTROL, KERN_WARNING,
+				"%s: connect failed: %d\n",
+				session->name, error);
+		else
+			PRINTK(-1, PPPOL2TP_MSG_CONTROL, KERN_WARNING,
+				"connect failed: %d\n", error);
+	}
+
+	return error;
+}
+
+/* getname() support.
+ */
+static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
+			    int *usockaddr_len, int peer)
+{
+	int len = sizeof(struct sockaddr_pppol2tp);
+	struct sockaddr_pppol2tp sp;
+	int error = 0;
+	struct pppol2tp_session *session;
+
+	error = -ENOTCONN;
+	if (sock->sk->sk_state != PPPOX_CONNECTED)
+		goto end;
+
+	session = pppol2tp_sock_to_session(sock->sk);
+	if (session == NULL) {
+		error = -EBADF;
+		goto end;
+	}
+
+	sp.sa_family	= AF_PPPOX;
+	sp.sa_protocol	= PX_PROTO_OL2TP;
+	memcpy(&sp.pppol2tp, &session->tunnel_addr,
+	       sizeof(struct pppol2tp_addr));
+
+	memcpy(uaddr, &sp, len);
+
+	*usockaddr_len = len;
+
+	error = 0;
+	sock_put(sock->sk);
+
+end:
+	return error;
+}
+
+/****************************************************************************
+ * ioctl() handlers.
+ *
+ * The PPPoX socket is created for L2TP sessions: tunnels have their own UDP
+ * sockets. However, in order to control kernel tunnel features, we allow
+ * userspace to create a special "tunnel" PPPoX socket which is used for
+ * control only.  Tunnel PPPoX sockets have session_id == 0 and simply allow
+ * the user application to issue L2TP setsockopt(), getsockopt() and ioctl()
+ * calls.
+ ****************************************************************************/
+
+/* Session ioctl helper.
+ */
+static int pppol2tp_session_ioctl(struct pppol2tp_session *session,
+				  unsigned int cmd, unsigned long arg)
+{
+	struct ifreq ifr;
+	int err = 0;
+	struct sock *sk = session->sock;
+	int val = (int) arg;
+
+	PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_DEBUG,
+	       "%s: pppol2tp_session_ioctl(cmd=%#x, arg=%#lx)\n",
+	       session->name, cmd, arg);
+
+	sock_hold(sk);
+
+	switch (cmd) {
+	case SIOCGIFMTU:
+		err = -ENXIO;
+		if (!(sk->sk_state & PPPOX_CONNECTED))
+			break;
+
+		err = -EFAULT;
+		if (copy_from_user(&ifr, (void __user *) arg, sizeof(struct ifreq)))
+			break;
+		ifr.ifr_mtu = session->mtu;
+		if (copy_to_user((void __user *) arg, &ifr, sizeof(struct ifreq)))
+			break;
+
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get mtu=%d\n", session->name, session->mtu);
+		err = 0;
+		break;
+
+	case SIOCSIFMTU:
+		err = -ENXIO;
+		if (!(sk->sk_state & PPPOX_CONNECTED))
+			break;
+
+		err = -EFAULT;
+		if (copy_from_user(&ifr, (void __user *) arg, sizeof(struct ifreq)))
+			break;
+
+		session->mtu = ifr.ifr_mtu;
+
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: set mtu=%d\n", session->name, session->mtu);
+		err = 0;
+		break;
+
+	case PPPIOCGMRU:
+		err = -ENXIO;
+		if (!(sk->sk_state & PPPOX_CONNECTED))
+			break;
+
+		err = -EFAULT;
+		if (put_user(session->mru, (int __user *) arg))
+			break;
+
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get mru=%d\n", session->name, session->mru);
+		err = 0;
+		break;
+
+	case PPPIOCSMRU:
+		err = -ENXIO;
+		if (!(sk->sk_state & PPPOX_CONNECTED))
+			break;
+
+		err = -EFAULT;
+		if (get_user(val,(int __user *) arg))
+			break;
+
+		session->mru = val;
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: set mru=%d\n", session->name, session->mru);
+		err = 0;
+		break;
+
+	case PPPIOCGFLAGS:
+		err = -EFAULT;
+		if (put_user(session->flags, (int __user *) arg))
+			break;
+
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get flags=%d\n", session->name, session->flags);
+		err = 0;
+		break;
+
+	case PPPIOCSFLAGS:
+		err = -EFAULT;
+		if (get_user(val, (int __user *) arg))
+			break;
+		session->flags = val;
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: set flags=%d\n", session->name, session->flags);
+		err = 0;
+		break;
+
+	case PPPIOCGL2TPSTATS:
+		err = -ENXIO;
+		if (!(sk->sk_state & PPPOX_CONNECTED))
+			break;
+
+		if (copy_to_user((void __user *) arg, &session->stats,
+				 sizeof(session->stats)))
+			break;
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get L2TP stats\n", session->name);
+		err = 0;
+		break;
+
+	default:
+		err = -ENOSYS;
+		break;
+	}
+
+	sock_put(sk);
+
+	return err;
+}
+
+/* Tunnel ioctl helper.
+ *
+ * Note the special handling for PPPIOCGL2TPSTATS below. If the ioctl data
+ * specifies a session_id, the session ioctl handler is called. This allows an
+ * application to retrieve session stats via a tunnel socket.
+ */
+static int pppol2tp_tunnel_ioctl(struct pppol2tp_tunnel *tunnel,
+				 unsigned int cmd, unsigned long arg)
+{
+	int err = 0;
+	struct sock *sk = tunnel->sock;
+	struct pppol2tp_ioc_stats stats_req;
+
+	PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_DEBUG,
+	       "%s: pppol2tp_tunnel_ioctl(cmd=%#x, arg=%#lx)\n", tunnel->name,
+	       cmd, arg);
+
+	sock_hold(sk);
+
+	switch (cmd) {
+	case PPPIOCGL2TPSTATS:
+		err = -ENXIO;
+		if (!(sk->sk_state & PPPOX_CONNECTED))
+			break;
+
+		if (copy_from_user(&stats_req, (void __user *) arg,
+				   sizeof(stats_req))) {
+			err = -EFAULT;
+			break;
+		}
+		if (stats_req.session_id != 0) {
+			/* resend to session ioctl handler */
+			struct pppol2tp_session *session =
+				pppol2tp_session_find(tunnel, stats_req.session_id);
+			if (session != NULL)
+				err = pppol2tp_session_ioctl(session, cmd, arg);
+			else
+				err = -EBADR;
+			break;
+		}
+#ifdef CONFIG_XFRM
+		tunnel->stats.using_ipsec = (sk->sk_policy[0] || sk->sk_policy[1]) ? 1 : 0;
+#endif
+		if (copy_to_user((void __user *) arg, &tunnel->stats,
+				 sizeof(tunnel->stats))) {
+			err = -EFAULT;
+			break;
+		}
+		PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get L2TP stats\n", tunnel->name);
+		err = 0;
+		break;
+
+	default:
+		err = -ENOSYS;
+		break;
+	}
+
+	sock_put(sk);
+
+	return err;
+}
+
+/* Main ioctl() handler.
+ * Dispatch to tunnel or session helpers depending on the socket.
+ */
+static int pppol2tp_ioctl(struct socket *sock, unsigned int cmd,
+			  unsigned long arg)
+{
+	struct sock *sk = sock->sk;
+	struct pppol2tp_session *session;
+	struct pppol2tp_tunnel *tunnel;
+	int err;
+
+	if (!sk)
+		return 0;
+
+	err = -EBADF;
+	if (sock_flag(sk, SOCK_DEAD) != 0)
+		goto end;
+
+	err = -ENOTCONN;
+	if ((sk->sk_user_data == NULL) ||
+	    (!(sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND))))
+		goto end;
+
+	/* Get session context from the socket */
+	err = -EBADF;
+	session = pppol2tp_sock_to_session(sk);
+	if (session == NULL)
+		goto end;
+
+	/* Special case: if session's session_id is zero, treat ioctl as a
+	 * tunnel ioctl
+	 */
+	if ((session->tunnel_addr.s_session == 0) &&
+	    (session->tunnel_addr.d_session == 0)) {
+		err = -EBADF;
+		tunnel = pppol2tp_sock_to_tunnel(session->tunnel_sock);
+		if (tunnel == NULL)
+			goto end_put_sess;
+
+		err = pppol2tp_tunnel_ioctl(tunnel, cmd, arg);
+		sock_put(session->tunnel_sock);
+		goto end_put_sess;
+	}
+
+	err = pppol2tp_session_ioctl(session, cmd, arg);
+
+end_put_sess:
+	sock_put(sk);
+end:
+	return err;
+}
+
+/*****************************************************************************
+ * setsockopt() / getsockopt() support.
+ *
+ * The PPPoX socket is created for L2TP sessions: tunnels have their own UDP
+ * sockets. In order to control kernel tunnel features, we allow userspace to
+ * create a special "tunnel" PPPoX socket which is used for control only.
+ * Tunnel PPPoX sockets have session_id == 0 and simply allow the user
+ * application to issue L2TP setsockopt(), getsockopt() and ioctl() calls.
+ *****************************************************************************/
+
+/* Tunnel setsockopt() helper.
+ */
+static int pppol2tp_tunnel_setsockopt(struct sock *sk,
+				      struct pppol2tp_tunnel *tunnel,
+				      int optname, int val)
+{
+	int err = 0;
+
+	switch (optname) {
+	case PPPOL2TP_SO_DEBUG:
+		tunnel->debug = val;
+		PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: set debug=%x\n", tunnel->name, tunnel->debug);
+		break;
+
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+
+	return err;
+}
+
+/* Session setsockopt helper.
+ */
+static int pppol2tp_session_setsockopt(struct sock *sk,
+				       struct pppol2tp_session *session,
+				       int optname, int val)
+{
+	int err = 0;
+
+	switch (optname) {
+	case PPPOL2TP_SO_RECVSEQ:
+		if ((val != 0) && (val != 1)) {
+			err = -EINVAL;
+			break;
+		}
+		session->recv_seq = val ? -1 : 0;
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: set recv_seq=%d\n", session->name,
+		       session->recv_seq);
+		break;
+
+	case PPPOL2TP_SO_SENDSEQ:
+		if ((val != 0) && (val != 1)) {
+			err = -EINVAL;
+			break;
+		}
+		session->send_seq = val ? -1 : 0;
+		{
+			struct sock *ssk      = session->sock;
+			struct pppox_sock *po = pppox_sk(ssk);
+			po->chan.hdrlen = val ? PPPOL2TP_L2TP_HDR_SIZE_SEQ :
+				PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
+		}
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: set send_seq=%d\n", session->name, session->send_seq);
+		break;
+
+	case PPPOL2TP_SO_LNSMODE:
+		if ((val != 0) && (val != 1)) {
+			err = -EINVAL;
+			break;
+		}
+		session->lns_mode = val ? -1 : 0;
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: set lns_mode=%d\n", session->name,
+		       session->lns_mode);
+		break;
+
+	case PPPOL2TP_SO_DEBUG:
+		session->debug = val;
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: set debug=%x\n", session->name, session->debug);
+		break;
+
+	case PPPOL2TP_SO_REORDERTO:
+		session->reorder_timeout = msecs_to_jiffies(val);
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: set reorder_timeout=%d\n", session->name,
+		       session->reorder_timeout);
+		break;
+
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+
+	return err;
+}
+
+/* Main setsockopt() entry point.
+ * Does API checks, then calls either the tunnel or session setsockopt
+ * handler, according to whether the PPPoL2TP socket is a for a regular
+ * session or the special tunnel type.
+ */
+static int pppol2tp_setsockopt(struct socket *sock, int level, int optname,
+			       char __user *optval, unsigned int optlen)
+{
+	struct sock *sk = sock->sk;
+	struct pppol2tp_session *session = sk->sk_user_data;
+	struct pppol2tp_tunnel *tunnel;
+	int val;
+	int err;
+
+	if (level != SOL_PPPOL2TP)
+		return udp_prot.setsockopt(sk, level, optname, optval, optlen);
+
+	if (optlen < sizeof(int))
+		return -EINVAL;
+
+	if (get_user(val, (int __user *)optval))
+		return -EFAULT;
+
+	err = -ENOTCONN;
+	if (sk->sk_user_data == NULL)
+		goto end;
+
+	/* Get session context from the socket */
+	err = -EBADF;
+	session = pppol2tp_sock_to_session(sk);
+	if (session == NULL)
+		goto end;
+
+	/* Special case: if session_id == 0x0000, treat as operation on tunnel
+	 */
+	if ((session->tunnel_addr.s_session == 0) &&
+	    (session->tunnel_addr.d_session == 0)) {
+		err = -EBADF;
+		tunnel = pppol2tp_sock_to_tunnel(session->tunnel_sock);
+		if (tunnel == NULL)
+			goto end_put_sess;
+
+		err = pppol2tp_tunnel_setsockopt(sk, tunnel, optname, val);
+		sock_put(session->tunnel_sock);
+	} else
+		err = pppol2tp_session_setsockopt(sk, session, optname, val);
+
+	err = 0;
+
+end_put_sess:
+	sock_put(sk);
+end:
+	return err;
+}
+
+/* Tunnel getsockopt helper. Called with sock locked.
+ */
+static int pppol2tp_tunnel_getsockopt(struct sock *sk,
+				      struct pppol2tp_tunnel *tunnel,
+				      int optname, int *val)
+{
+	int err = 0;
+
+	switch (optname) {
+	case PPPOL2TP_SO_DEBUG:
+		*val = tunnel->debug;
+		PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get debug=%x\n", tunnel->name, tunnel->debug);
+		break;
+
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+
+	return err;
+}
+
+/* Session getsockopt helper. Called with sock locked.
+ */
+static int pppol2tp_session_getsockopt(struct sock *sk,
+				       struct pppol2tp_session *session,
+				       int optname, int *val)
+{
+	int err = 0;
+
+	switch (optname) {
+	case PPPOL2TP_SO_RECVSEQ:
+		*val = session->recv_seq;
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get recv_seq=%d\n", session->name, *val);
+		break;
+
+	case PPPOL2TP_SO_SENDSEQ:
+		*val = session->send_seq;
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get send_seq=%d\n", session->name, *val);
+		break;
+
+	case PPPOL2TP_SO_LNSMODE:
+		*val = session->lns_mode;
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get lns_mode=%d\n", session->name, *val);
+		break;
+
+	case PPPOL2TP_SO_DEBUG:
+		*val = session->debug;
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get debug=%d\n", session->name, *val);
+		break;
+
+	case PPPOL2TP_SO_REORDERTO:
+		*val = (int) jiffies_to_msecs(session->reorder_timeout);
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get reorder_timeout=%d\n", session->name, *val);
+		break;
+
+	default:
+		err = -ENOPROTOOPT;
+	}
+
+	return err;
+}
+
+/* Main getsockopt() entry point.
+ * Does API checks, then calls either the tunnel or session getsockopt
+ * handler, according to whether the PPPoX socket is a for a regular session
+ * or the special tunnel type.
+ */
+static int pppol2tp_getsockopt(struct socket *sock, int level,
+			       int optname, char __user *optval, int __user *optlen)
+{
+	struct sock *sk = sock->sk;
+	struct pppol2tp_session *session = sk->sk_user_data;
+	struct pppol2tp_tunnel *tunnel;
+	int val, len;
+	int err;
+
+	if (level != SOL_PPPOL2TP)
+		return udp_prot.getsockopt(sk, level, optname, optval, optlen);
+
+	if (get_user(len, (int __user *) optlen))
+		return -EFAULT;
+
+	len = min_t(unsigned int, len, sizeof(int));
+
+	if (len < 0)
+		return -EINVAL;
+
+	err = -ENOTCONN;
+	if (sk->sk_user_data == NULL)
+		goto end;
+
+	/* Get the session context */
+	err = -EBADF;
+	session = pppol2tp_sock_to_session(sk);
+	if (session == NULL)
+		goto end;
+
+	/* Special case: if session_id == 0x0000, treat as operation on tunnel */
+	if ((session->tunnel_addr.s_session == 0) &&
+	    (session->tunnel_addr.d_session == 0)) {
+		err = -EBADF;
+		tunnel = pppol2tp_sock_to_tunnel(session->tunnel_sock);
+		if (tunnel == NULL)
+			goto end_put_sess;
+
+		err = pppol2tp_tunnel_getsockopt(sk, tunnel, optname, &val);
+		sock_put(session->tunnel_sock);
+	} else
+		err = pppol2tp_session_getsockopt(sk, session, optname, &val);
+
+	err = -EFAULT;
+	if (put_user(len, (int __user *) optlen))
+		goto end_put_sess;
+
+	if (copy_to_user((void __user *) optval, &val, len))
+		goto end_put_sess;
+
+	err = 0;
+
+end_put_sess:
+	sock_put(sk);
+end:
+	return err;
+}
+
+/*****************************************************************************
+ * /proc filesystem for debug
+ *****************************************************************************/
+
+#ifdef CONFIG_PROC_FS
+
+#include <linux/seq_file.h>
+
+struct pppol2tp_seq_data {
+	struct seq_net_private p;
+	struct pppol2tp_tunnel *tunnel;		/* current tunnel */
+	struct pppol2tp_session *session;	/* NULL means get first session in tunnel */
+};
+
+static struct pppol2tp_session *next_session(struct pppol2tp_tunnel *tunnel, struct pppol2tp_session *curr)
+{
+	struct pppol2tp_session *session = NULL;
+	struct hlist_node *walk;
+	int found = 0;
+	int next = 0;
+	int i;
+
+	read_lock_bh(&tunnel->hlist_lock);
+	for (i = 0; i < PPPOL2TP_HASH_SIZE; i++) {
+		hlist_for_each_entry(session, walk, &tunnel->session_hlist[i], hlist) {
+			if (curr == NULL) {
+				found = 1;
+				goto out;
+			}
+			if (session == curr) {
+				next = 1;
+				continue;
+			}
+			if (next) {
+				found = 1;
+				goto out;
+			}
+		}
+	}
+out:
+	read_unlock_bh(&tunnel->hlist_lock);
+	if (!found)
+		session = NULL;
+
+	return session;
+}
+
+static struct pppol2tp_tunnel *next_tunnel(struct pppol2tp_net *pn,
+					   struct pppol2tp_tunnel *curr)
+{
+	struct pppol2tp_tunnel *tunnel = NULL;
+
+	read_lock_bh(&pn->pppol2tp_tunnel_list_lock);
+	if (list_is_last(&curr->list, &pn->pppol2tp_tunnel_list)) {
+		goto out;
+	}
+	tunnel = list_entry(curr->list.next, struct pppol2tp_tunnel, list);
+out:
+	read_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
+
+	return tunnel;
+}
+
+static void *pppol2tp_seq_start(struct seq_file *m, loff_t *offs)
+{
+	struct pppol2tp_seq_data *pd = SEQ_START_TOKEN;
+	struct pppol2tp_net *pn;
+	loff_t pos = *offs;
+
+	if (!pos)
+		goto out;
+
+	BUG_ON(m->private == NULL);
+	pd = m->private;
+	pn = pppol2tp_pernet(seq_file_net(m));
+
+	if (pd->tunnel == NULL) {
+		if (!list_empty(&pn->pppol2tp_tunnel_list))
+			pd->tunnel = list_entry(pn->pppol2tp_tunnel_list.next, struct pppol2tp_tunnel, list);
+	} else {
+		pd->session = next_session(pd->tunnel, pd->session);
+		if (pd->session == NULL) {
+			pd->tunnel = next_tunnel(pn, pd->tunnel);
+		}
+	}
+
+	/* NULL tunnel and session indicates end of list */
+	if ((pd->tunnel == NULL) && (pd->session == NULL))
+		pd = NULL;
+
+out:
+	return pd;
+}
+
+static void *pppol2tp_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	(*pos)++;
+	return NULL;
+}
+
+static void pppol2tp_seq_stop(struct seq_file *p, void *v)
+{
+	/* nothing to do */
+}
+
+static void pppol2tp_seq_tunnel_show(struct seq_file *m, void *v)
+{
+	struct pppol2tp_tunnel *tunnel = v;
+
+	seq_printf(m, "\nTUNNEL '%s', %c %d\n",
+		   tunnel->name,
+		   (tunnel == tunnel->sock->sk_user_data) ? 'Y':'N',
+		   atomic_read(&tunnel->ref_count) - 1);
+	seq_printf(m, " %08x %llu/%llu/%llu %llu/%llu/%llu\n",
+		   tunnel->debug,
+		   (unsigned long long)tunnel->stats.tx_packets,
+		   (unsigned long long)tunnel->stats.tx_bytes,
+		   (unsigned long long)tunnel->stats.tx_errors,
+		   (unsigned long long)tunnel->stats.rx_packets,
+		   (unsigned long long)tunnel->stats.rx_bytes,
+		   (unsigned long long)tunnel->stats.rx_errors);
+}
+
+static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
+{
+	struct pppol2tp_session *session = v;
+
+	seq_printf(m, "  SESSION '%s' %08X/%d %04X/%04X -> "
+		   "%04X/%04X %d %c\n",
+		   session->name,
+		   ntohl(session->tunnel_addr.addr.sin_addr.s_addr),
+		   ntohs(session->tunnel_addr.addr.sin_port),
+		   session->tunnel_addr.s_tunnel,
+		   session->tunnel_addr.s_session,
+		   session->tunnel_addr.d_tunnel,
+		   session->tunnel_addr.d_session,
+		   session->sock->sk_state,
+		   (session == session->sock->sk_user_data) ?
+		   'Y' : 'N');
+	seq_printf(m, "   %d/%d/%c/%c/%s %08x %u\n",
+		   session->mtu, session->mru,
+		   session->recv_seq ? 'R' : '-',
+		   session->send_seq ? 'S' : '-',
+		   session->lns_mode ? "LNS" : "LAC",
+		   session->debug,
+		   jiffies_to_msecs(session->reorder_timeout));
+	seq_printf(m, "   %hu/%hu %llu/%llu/%llu %llu/%llu/%llu\n",
+		   session->nr, session->ns,
+		   (unsigned long long)session->stats.tx_packets,
+		   (unsigned long long)session->stats.tx_bytes,
+		   (unsigned long long)session->stats.tx_errors,
+		   (unsigned long long)session->stats.rx_packets,
+		   (unsigned long long)session->stats.rx_bytes,
+		   (unsigned long long)session->stats.rx_errors);
+}
+
+static int pppol2tp_seq_show(struct seq_file *m, void *v)
+{
+	struct pppol2tp_seq_data *pd = v;
+
+	/* display header on line 1 */
+	if (v == SEQ_START_TOKEN) {
+		seq_puts(m, "PPPoL2TP driver info, " PPPOL2TP_DRV_VERSION "\n");
+		seq_puts(m, "TUNNEL name, user-data-ok session-count\n");
+		seq_puts(m, " debug tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
+		seq_puts(m, "  SESSION name, addr/port src-tid/sid "
+			 "dest-tid/sid state user-data-ok\n");
+		seq_puts(m, "   mtu/mru/rcvseq/sendseq/lns debug reorderto\n");
+		seq_puts(m, "   nr/ns tx-pkts/bytes/errs rx-pkts/bytes/errs\n");
+		goto out;
+	}
+
+	/* Show the tunnel or session context.
+	 */
+	if (pd->session == NULL)
+		pppol2tp_seq_tunnel_show(m, pd->tunnel);
+	else
+		pppol2tp_seq_session_show(m, pd->session);
+
+out:
+	return 0;
+}
+
+static const struct seq_operations pppol2tp_seq_ops = {
+	.start		= pppol2tp_seq_start,
+	.next		= pppol2tp_seq_next,
+	.stop		= pppol2tp_seq_stop,
+	.show		= pppol2tp_seq_show,
+};
+
+/* Called when our /proc file is opened. We allocate data for use when
+ * iterating our tunnel / session contexts and store it in the private
+ * data of the seq_file.
+ */
+static int pppol2tp_proc_open(struct inode *inode, struct file *file)
+{
+	return seq_open_net(inode, file, &pppol2tp_seq_ops,
+			    sizeof(struct pppol2tp_seq_data));
+}
+
+static const struct file_operations pppol2tp_proc_fops = {
+	.owner		= THIS_MODULE,
+	.open		= pppol2tp_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release_net,
+};
+
+#endif /* CONFIG_PROC_FS */
+
+/*****************************************************************************
+ * Init and cleanup
+ *****************************************************************************/
+
+static const struct proto_ops pppol2tp_ops = {
+	.family		= AF_PPPOX,
+	.owner		= THIS_MODULE,
+	.release	= pppol2tp_release,
+	.bind		= sock_no_bind,
+	.connect	= pppol2tp_connect,
+	.socketpair	= sock_no_socketpair,
+	.accept		= sock_no_accept,
+	.getname	= pppol2tp_getname,
+	.poll		= datagram_poll,
+	.listen		= sock_no_listen,
+	.shutdown	= sock_no_shutdown,
+	.setsockopt	= pppol2tp_setsockopt,
+	.getsockopt	= pppol2tp_getsockopt,
+	.sendmsg	= pppol2tp_sendmsg,
+	.recvmsg	= pppol2tp_recvmsg,
+	.mmap		= sock_no_mmap,
+	.ioctl		= pppox_ioctl,
+};
+
+static struct pppox_proto pppol2tp_proto = {
+	.create		= pppol2tp_create,
+	.ioctl		= pppol2tp_ioctl
+};
+
+static __net_init int pppol2tp_init_net(struct net *net)
+{
+	struct pppol2tp_net *pn = pppol2tp_pernet(net);
+	struct proc_dir_entry *pde;
+
+	INIT_LIST_HEAD(&pn->pppol2tp_tunnel_list);
+	rwlock_init(&pn->pppol2tp_tunnel_list_lock);
+
+	pde = proc_net_fops_create(net, "pppol2tp", S_IRUGO, &pppol2tp_proc_fops);
+#ifdef CONFIG_PROC_FS
+	if (!pde)
+		return -ENOMEM;
+#endif
+
+	return 0;
+}
+
+static __net_exit void pppol2tp_exit_net(struct net *net)
+{
+	proc_net_remove(net, "pppol2tp");
+}
+
+static struct pernet_operations pppol2tp_net_ops = {
+	.init = pppol2tp_init_net,
+	.exit = pppol2tp_exit_net,
+	.id   = &pppol2tp_net_id,
+	.size = sizeof(struct pppol2tp_net),
+};
+
+static int __init pppol2tp_init(void)
+{
+	int err;
+
+	err = proto_register(&pppol2tp_sk_proto, 0);
+	if (err)
+		goto out;
+	err = register_pppox_proto(PX_PROTO_OL2TP, &pppol2tp_proto);
+	if (err)
+		goto out_unregister_pppol2tp_proto;
+
+	err = register_pernet_device(&pppol2tp_net_ops);
+	if (err)
+		goto out_unregister_pppox_proto;
+
+	printk(KERN_INFO "PPPoL2TP kernel driver, %s\n",
+	       PPPOL2TP_DRV_VERSION);
+
+out:
+	return err;
+out_unregister_pppox_proto:
+	unregister_pppox_proto(PX_PROTO_OL2TP);
+out_unregister_pppol2tp_proto:
+	proto_unregister(&pppol2tp_sk_proto);
+	goto out;
+}
+
+static void __exit pppol2tp_exit(void)
+{
+	unregister_pppox_proto(PX_PROTO_OL2TP);
+	unregister_pernet_device(&pppol2tp_net_ops);
+	proto_unregister(&pppol2tp_sk_proto);
+}
+
+module_init(pppol2tp_init);
+module_exit(pppol2tp_exit);
+
+MODULE_AUTHOR("Martijn van Oosterhout <kleptog@svana.org>, "
+	      "James Chapman <jchapman@katalix.com>");
+MODULE_DESCRIPTION("PPP over L2TP over UDP");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(PPPOL2TP_DRV_VERSION);
