l2tp: Split pppol2tp patch into separate l2tp and ppp parts

This patch splits the pppol2tp driver into separate L2TP and PPP parts
to prepare for L2TPv3 support. In L2TPv3, protocols other than PPP can
be carried, so this split creates a common L2TP core that will handle
the common L2TP bits which protocol support modules such as PPP will
use.

Note that the existing pppol2tp module is split into l2tp_core and
l2tp_ppp by this change.

There are no feature changes here. Internally, however, there are
significant changes, mostly to handle the separation of PPP-specific
data from the L2TP session and to provide hooks in the core for
modules like PPP to access.

Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 3171 insertions, 2681 deletions

diff --git a/net/l2tp/Kconfig b/net/l2tp/Kconfig
new file mode 100644
index 000000000000..ec88c5cdc397
--- /dev/null
+++ b/net/l2tp/Kconfig
@@ -0,0 +1,28 @@
+#
+# Layer Two Tunneling Protocol (L2TP)
+#
+
+menuconfig L2TP
+	tristate "Layer Two Tunneling Protocol (L2TP)"
+	depends on INET
+	---help---
+	  Layer Two Tunneling Protocol
+
+	  From RFC 2661 <http://www.ietf.org/rfc/rfc2661.txt>.
+
+	  L2TP facilitates the tunneling of packets across an
+	  intervening network in a way that is as transparent as
+	  possible to both end-users and applications.
+
+	  L2TP is often used to tunnel PPP traffic over IP
+	  tunnels. One IP tunnel may carry thousands of individual PPP
+	  connections. L2TP is also used as a VPN protocol, popular
+	  with home workers to connect to their offices.
+
+	  The kernel component handles only L2TP data packets: a
+	  userland daemon handles L2TP the control protocol (tunnel
+	  and session setup). One such daemon is OpenL2TP
+	  (http://openl2tp.org/).
+
+	  If you don't need L2TP, say N. To compile all L2TP code as
+	  modules, choose M here.
diff --git a/net/l2tp/Makefile b/net/l2tp/Makefile
index 9af41e898a04..c91f208b1693 100644
--- a/net/l2tp/Makefile
+++ b/net/l2tp/Makefile
@@ -2,4 +2,7 @@
 # Makefile for the L2TP.
 #
 
-obj-$(CONFIG_PPPOL2TP) += pppol2tp.o
+obj-$(CONFIG_L2TP) += l2tp_core.o
+
+# Build l2tp as modules if L2TP is M
+obj-$(subst y,$(CONFIG_L2TP),$(CONFIG_PPPOL2TP)) += l2tp_ppp.o
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
new file mode 100644
index 000000000000..4b6da3689893
--- /dev/null
+++ b/net/l2tp/l2tp_core.c
@@ -0,0 +1,1227 @@
+/*
+ * L2TP core.
+ *
+ * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
+ *
+ * This file contains some code of the original L2TPv2 pppol2tp
+ * driver, which has the following copyright:
+ *
+ * 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)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/list.h>
+#include <linux/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/hash.h>
+#include <linux/sort.h>
+#include <linux/file.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>
+
+#include "l2tp_core.h"
+
+#define L2TP_DRV_VERSION	"V2.0"
+
+/* 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_2	   0x0002
+
+/* L2TPv3 default L2-specific sublayer */
+#define L2TP_SLFLAG_S	   0x40000000
+#define L2TP_SL_SEQ_MASK   0x00ffffff
+
+#define L2TP_HDR_SIZE_SEQ		10
+#define L2TP_HDR_SIZE_NOSEQ		6
+
+/* Default trace flags */
+#define L2TP_DEFAULT_DEBUG_FLAGS	0
+
+#define PRINTK(_mask, _type, _lvl, _fmt, args...)			\
+	do {								\
+		if ((_mask) & (_type))					\
+			printk(_lvl "L2TP: " _fmt, ##args);		\
+	} while (0)
+
+/* Private data stored for received packets in the skb.
+ */
+struct l2tp_skb_cb {
+	u16			ns;
+	u16			has_seq;
+	u16			length;
+	unsigned long		expires;
+};
+
+#define L2TP_SKB_CB(skb)	((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
+
+static atomic_t l2tp_tunnel_count;
+static atomic_t l2tp_session_count;
+
+/* per-net private data for this module */
+static unsigned int l2tp_net_id;
+struct l2tp_net {
+	struct list_head l2tp_tunnel_list;
+	rwlock_t l2tp_tunnel_list_lock;
+};
+
+static inline struct l2tp_net *l2tp_pernet(struct net *net)
+{
+	BUG_ON(!net);
+
+	return net_generic(net, l2tp_net_id);
+}
+
+/* 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 *
+l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
+{
+	return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
+}
+
+/* Lookup a session by id
+ */
+struct l2tp_session *l2tp_session_find(struct l2tp_tunnel *tunnel, u32 session_id)
+{
+	struct hlist_head *session_list =
+		l2tp_session_id_hash(tunnel, session_id);
+	struct l2tp_session *session;
+	struct hlist_node *walk;
+
+	read_lock_bh(&tunnel->hlist_lock);
+	hlist_for_each_entry(session, walk, session_list, hlist) {
+		if (session->session_id == session_id) {
+			read_unlock_bh(&tunnel->hlist_lock);
+			return session;
+		}
+	}
+	read_unlock_bh(&tunnel->hlist_lock);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_find);
+
+struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth)
+{
+	int hash;
+	struct hlist_node *walk;
+	struct l2tp_session *session;
+	int count = 0;
+
+	read_lock_bh(&tunnel->hlist_lock);
+	for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
+		hlist_for_each_entry(session, walk, &tunnel->session_hlist[hash], hlist) {
+			if (++count > nth) {
+				read_unlock_bh(&tunnel->hlist_lock);
+				return session;
+			}
+		}
+	}
+
+	read_unlock_bh(&tunnel->hlist_lock);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_find_nth);
+
+/* Lookup a tunnel by id
+ */
+struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
+{
+	struct l2tp_tunnel *tunnel;
+	struct l2tp_net *pn = l2tp_pernet(net);
+
+	read_lock_bh(&pn->l2tp_tunnel_list_lock);
+	list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) {
+		if (tunnel->tunnel_id == tunnel_id) {
+			read_unlock_bh(&pn->l2tp_tunnel_list_lock);
+			return tunnel;
+		}
+	}
+	read_unlock_bh(&pn->l2tp_tunnel_list_lock);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
+
+struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
+{
+	struct l2tp_net *pn = l2tp_pernet(net);
+	struct l2tp_tunnel *tunnel;
+	int count = 0;
+
+	read_lock_bh(&pn->l2tp_tunnel_list_lock);
+	list_for_each_entry(tunnel, &pn->l2tp_tunnel_list, list) {
+		if (++count > nth) {
+			read_unlock_bh(&pn->l2tp_tunnel_list_lock);
+			return tunnel;
+		}
+	}
+
+	read_unlock_bh(&pn->l2tp_tunnel_list_lock);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);
+
+/*****************************************************************************
+ * Receive data handling
+ *****************************************************************************/
+
+/* Queue a skb in order. We come here only if the skb has an L2TP sequence
+ * number.
+ */
+static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
+{
+	struct sk_buff *skbp;
+	struct sk_buff *tmp;
+	u16 ns = L2TP_SKB_CB(skb)->ns;
+
+	spin_lock_bh(&session->reorder_q.lock);
+	skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
+		if (L2TP_SKB_CB(skbp)->ns > ns) {
+			__skb_queue_before(&session->reorder_q, skbp, skb);
+			PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
+			       "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
+			       session->name, ns, L2TP_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 l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
+{
+	struct l2tp_tunnel *tunnel = session->tunnel;
+	int length = L2TP_SKB_CB(skb)->length;
+
+	/* 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 (L2TP_SKB_CB(skb)->has_seq) {
+		/* Bump our Nr */
+		session->nr++;
+		PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
+		       "%s: updated nr to %hu\n", session->name, session->nr);
+	}
+
+	/* call private receive handler */
+	if (session->recv_skb != NULL)
+		(*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
+	else
+		kfree_skb(skb);
+
+	if (session->deref)
+		(*session->deref)(session);
+}
+
+/* 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 l2tp_recv_dequeue(struct l2tp_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, L2TP_SKB_CB(skb)->expires)) {
+			session->stats.rx_seq_discards++;
+			session->stats.rx_errors++;
+			PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
+			       "%s: oos pkt %hu len %d discarded (too old), "
+			       "waiting for %hu, reorder_q_len=%d\n",
+			       session->name, L2TP_SKB_CB(skb)->ns,
+			       L2TP_SKB_CB(skb)->length, session->nr,
+			       skb_queue_len(&session->reorder_q));
+			__skb_unlink(skb, &session->reorder_q);
+			kfree_skb(skb);
+			if (session->deref)
+				(*session->deref)(session);
+			continue;
+		}
+
+		if (L2TP_SKB_CB(skb)->has_seq) {
+			if (L2TP_SKB_CB(skb)->ns != session->nr) {
+				PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
+				       "%s: holding oos pkt %hu len %d, "
+				       "waiting for %hu, reorder_q_len=%d\n",
+				       session->name, L2TP_SKB_CB(skb)->ns,
+				       L2TP_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);
+		l2tp_recv_dequeue_skb(session, skb);
+		spin_lock_bh(&session->reorder_q.lock);
+	}
+
+out:
+	spin_unlock_bh(&session->reorder_q.lock);
+}
+
+static inline int l2tp_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 UDP 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.
+ */
+int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
+		       int (*payload_hook)(struct sk_buff *skb))
+{
+	struct l2tp_session *session = NULL;
+	unsigned char *ptr, *optr;
+	u16 hdrflags;
+	u32 tunnel_id, session_id;
+	int length;
+	int offset;
+	u16 version;
+	u16 ns, nr;
+
+	if (tunnel->sock && l2tp_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, L2TP_HDR_SIZE_SEQ)) {
+		PRINTK(tunnel->debug, L2TP_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;
+
+	/* Trace packet contents, if enabled */
+	if (tunnel->debug & L2TP_MSG_DATA) {
+		length = min(32u, 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 L2TP header flags */
+	hdrflags = ntohs(*(__be16 *)ptr);
+
+	/* Check protocol version */
+	version = hdrflags & L2TP_HDR_VER_MASK;
+	if (version != tunnel->version) {
+		PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
+		       "%s: recv protocol version mismatch: got %d expected %d\n",
+		       tunnel->name, version, tunnel->version);
+		goto error;
+	}
+
+	/* 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, L2TP_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 = l2tp_session_find(tunnel, session_id);
+	if (!session) {
+		/* Not found? Pass to userspace to deal with */
+		PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
+		       "%s: no session found (%hu/%hu). Passing up.\n",
+		       tunnel->name, tunnel_id, session_id);
+		goto error;
+	}
+
+	/* The ref count is increased since we now hold a pointer to
+	 * the session. Take care to decrement the refcnt when exiting
+	 * this function from now on...
+	 */
+	l2tp_session_inc_refcount(session);
+	if (session->ref)
+		(*session->ref)(session);
+
+	/* Handle the optional sequence numbers. Sequence numbers are
+	 * in different places for L2TPv2 and L2TPv3.
+	 *
+	 * 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.
+	 */
+	ns = nr = 0;
+	L2TP_SKB_CB(skb)->has_seq = 0;
+	if (hdrflags & L2TP_HDRFLAG_S) {
+		ns = (u16) ntohs(*(__be16 *) ptr);
+		ptr += 2;
+		nr = ntohs(*(__be16 *) ptr);
+		ptr += 2;
+
+		/* Store L2TP info in the skb */
+		L2TP_SKB_CB(skb)->ns = ns;
+		L2TP_SKB_CB(skb)->has_seq = 1;
+
+		PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
+		       "%s: recv data ns=%hu, nr=%hu, session nr=%hu\n",
+		       session->name, ns, nr, session->nr);
+	}
+
+	if (L2TP_SKB_CB(skb)->has_seq) {
+		/* 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, L2TP_MSG_SEQ, KERN_INFO,
+			       "%s: requested to enable seq numbers by LNS\n",
+			       session->name);
+			session->send_seq = -1;
+		}
+	} else {
+		/* No sequence numbers.
+		 * If user has configured mandatory sequence numbers, discard.
+		 */
+		if (session->recv_seq) {
+			PRINTK(session->debug, L2TP_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, L2TP_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, L2TP_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 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);
+
+	/* If caller wants to process the payload before we queue the
+	 * packet, do so now.
+	 */
+	if (payload_hook)
+		if ((*payload_hook)(skb))
+			goto discard;
+
+	/* Prepare skb for adding to the session's reorder_q.  Hold
+	 * packets for max reorder_timeout or 1 second if not
+	 * reordering.
+	 */
+	L2TP_SKB_CB(skb)->length = length;
+	L2TP_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 (L2TP_SKB_CB(skb)->has_seq) {
+		if (session->reorder_timeout != 0) {
+			/* Packet reordering enabled. Add skb to session's
+			 * reorder queue, in order of ns.
+			 */
+			l2tp_recv_queue_skb(session, skb);
+		} else {
+			/* Packet reordering disabled. Discard out-of-sequence
+			 * packets
+			 */
+			if (L2TP_SKB_CB(skb)->ns != session->nr) {
+				session->stats.rx_seq_discards++;
+				PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
+				       "%s: oos pkt %hu len %d discarded, "
+				       "waiting for %hu, reorder_q_len=%d\n",
+				       session->name, L2TP_SKB_CB(skb)->ns,
+				       L2TP_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. */
+	l2tp_recv_dequeue(session);
+
+	l2tp_session_dec_refcount(session);
+
+	return 0;
+
+discard:
+	session->stats.rx_errors++;
+	kfree_skb(skb);
+
+	if (session->deref)
+		(*session->deref)(session);
+
+	l2tp_session_dec_refcount(session);
+
+	return 0;
+
+discard_bad_csum:
+	LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
+	UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
+	tunnel->stats.rx_errors++;
+	kfree_skb(skb);
+
+	return 0;
+
+error:
+	/* Put UDP header back */
+	__skb_push(skb, sizeof(struct udphdr));
+
+	return 1;
+}
+EXPORT_SYMBOL_GPL(l2tp_udp_recv_core);
+
+/* 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.
+ */
+int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
+{
+	struct l2tp_tunnel *tunnel;
+
+	tunnel = l2tp_sock_to_tunnel(sk);
+	if (tunnel == NULL)
+		goto pass_up;
+
+	PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG,
+	       "%s: received %d bytes\n", tunnel->name, skb->len);
+
+	if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook))
+		goto pass_up_put;
+
+	sock_put(sk);
+	return 0;
+
+pass_up_put:
+	sock_put(sk);
+pass_up:
+	return 1;
+}
+EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
+
+/************************************************************************
+ * Transmit handling
+ ***********************************************************************/
+
+/* Build an L2TP header for the session into the buffer provided.
+ */
+static void l2tp_build_l2tpv2_header(struct l2tp_tunnel *tunnel,
+				     struct l2tp_session *session,
+				     void *buf)
+{
+	__be16 *bufp = buf;
+	u16 flags = L2TP_HDR_VER_2;
+	u32 tunnel_id = tunnel->peer_tunnel_id;
+	u32 session_id = session->peer_session_id;
+
+	if (session->send_seq)
+		flags |= L2TP_HDRFLAG_S;
+
+	/* Setup L2TP header. */
+	*bufp++ = htons(flags);
+	*bufp++ = htons(tunnel_id);
+	*bufp++ = htons(session_id);
+	if (session->send_seq) {
+		*bufp++ = htons(session->ns);
+		*bufp++ = 0;
+		session->ns++;
+		PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
+		       "%s: updated ns to %hu\n", session->name, session->ns);
+	}
+}
+
+void l2tp_build_l2tp_header(struct l2tp_session *session, void *buf)
+{
+	struct l2tp_tunnel *tunnel = session->tunnel;
+
+	BUG_ON(tunnel->version != L2TP_HDR_VER_2);
+	l2tp_build_l2tpv2_header(tunnel, session, buf);
+}
+EXPORT_SYMBOL_GPL(l2tp_build_l2tp_header);
+
+int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, size_t data_len)
+{
+	struct l2tp_tunnel *tunnel = session->tunnel;
+	unsigned int len = skb->len;
+	int error;
+
+	/* Debug */
+	if (session->send_seq)
+		PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
+		       "%s: send %Zd bytes, ns=%hu\n", session->name,
+		       data_len, session->ns - 1);
+	else
+		PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG,
+		       "%s: send %Zd bytes\n", session->name, data_len);
+
+	if (session->debug & L2TP_MSG_DATA) {
+		int i;
+		unsigned char *datap = skb->data + sizeof(struct udphdr);
+
+		printk(KERN_DEBUG "%s: xmit:", session->name);
+		for (i = 0; i < (len - sizeof(struct udphdr)); i++) {
+			printk(" %02X", *datap++);
+			if (i == 31) {
+				printk(" ...");
+				break;
+			}
+		}
+		printk("\n");
+	}
+
+	/* Queue the packet to IP for output */
+	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 0;
+}
+EXPORT_SYMBOL_GPL(l2tp_xmit_core);
+
+/* Automatically called when the skb is freed.
+ */
+static void l2tp_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 l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
+{
+	sock_hold(sk);
+	skb->sk = sk;
+	skb->destructor = l2tp_sock_wfree;
+}
+
+/* If caller requires the skb to have a ppp header, the header must be
+ * inserted in the skb data before calling this function.
+ */
+int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
+{
+	int data_len = skb->len;
+	struct sock *sk = session->tunnel->sock;
+	struct udphdr *uh;
+	unsigned int udp_len;
+	struct inet_sock *inet;
+	__wsum csum;
+	int old_headroom;
+	int new_headroom;
+	int headroom;
+
+	/* Check that there's enough headroom in the skb to insert IP,
+	 * UDP and L2TP headers. If not enough, expand it to
+	 * make room. Adjust truesize.
+	 */
+	headroom = NET_SKB_PAD + sizeof(struct iphdr) +
+		sizeof(struct udphdr) + hdr_len;
+	old_headroom = skb_headroom(skb);
+	if (skb_cow_head(skb, headroom))
+		goto abort;
+
+	new_headroom = skb_headroom(skb);
+	skb_orphan(skb);
+	skb->truesize += new_headroom - old_headroom;
+
+	/* Setup L2TP header */
+	l2tp_build_l2tp_header(session, __skb_push(skb, hdr_len));
+	udp_len = sizeof(struct udphdr) + hdr_len + data_len;
+
+	/* Setup UDP header */
+	inet = inet_sk(sk);
+	__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;
+
+	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)));
+	l2tp_skb_set_owner_w(skb, sk);
+
+	/* Calculate UDP checksum if configured to do so */
+	if (sk->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);
+	}
+
+	l2tp_xmit_core(session, skb, data_len);
+
+abort:
+	return 0;
+}
+EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
+
+/*****************************************************************************
+ * Tinnel and session create/destroy.
+ *****************************************************************************/
+
+/* Tunnel socket destruct hook.
+ * The tunnel context is deleted only when all session sockets have been
+ * closed.
+ */
+void l2tp_tunnel_destruct(struct sock *sk)
+{
+	struct l2tp_tunnel *tunnel;
+
+	tunnel = sk->sk_user_data;
+	if (tunnel == NULL)
+		goto end;
+
+	PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
+	       "%s: closing...\n", tunnel->name);
+
+	/* Close all sessions */
+	l2tp_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 the original destructor */
+	if (sk->sk_destruct)
+		(*sk->sk_destruct)(sk);
+
+	/* We're finished with the socket */
+	l2tp_tunnel_dec_refcount(tunnel);
+
+end:
+	return;
+}
+EXPORT_SYMBOL(l2tp_tunnel_destruct);
+
+/* When the tunnel is closed, all the attached sessions need to go too.
+ */
+void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
+{
+	int hash;
+	struct hlist_node *walk;
+	struct hlist_node *tmp;
+	struct l2tp_session *session;
+
+	BUG_ON(tunnel == NULL);
+
+	PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
+	       "%s: closing all sessions...\n", tunnel->name);
+
+	write_lock_bh(&tunnel->hlist_lock);
+	for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
+again:
+		hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
+			session = hlist_entry(walk, struct l2tp_session, hlist);
+
+			PRINTK(session->debug, L2TP_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.
+			 */
+			if (session->ref != NULL)
+				(*session->ref)(session);
+
+			write_unlock_bh(&tunnel->hlist_lock);
+
+			if (session->session_close != NULL)
+				(*session->session_close)(session);
+
+			if (session->deref != NULL)
+				(*session->deref)(session);
+
+			write_lock_bh(&tunnel->hlist_lock);
+
+			/* 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.
+			 */
+			goto again;
+		}
+	}
+	write_unlock_bh(&tunnel->hlist_lock);
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall);
+
+/* Really kill the tunnel.
+ * Come here only when all sessions have been cleared from the tunnel.
+ */
+void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
+{
+	struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
+
+	BUG_ON(atomic_read(&tunnel->ref_count) != 0);
+	BUG_ON(tunnel->sock != NULL);
+
+	PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO,
+	       "%s: free...\n", tunnel->name);
+
+	/* Remove from tunnel list */
+	write_lock_bh(&pn->l2tp_tunnel_list_lock);
+	list_del_init(&tunnel->list);
+	write_unlock_bh(&pn->l2tp_tunnel_list_lock);
+
+	atomic_dec(&l2tp_tunnel_count);
+	kfree(tunnel);
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_free);
+
+int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp)
+{
+	struct l2tp_tunnel *tunnel = NULL;
+	int err;
+	struct socket *sock = NULL;
+	struct sock *sk = NULL;
+	struct l2tp_net *pn;
+
+	/* Get the tunnel socket from the fd, which was opened by
+	 * the userspace L2TP daemon.
+	 */
+	err = -EBADF;
+	sock = sockfd_lookup(fd, &err);
+	if (!sock) {
+		printk(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(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(KERN_ERR "tunl %hu: fd %d wrong family, got %d, expected %d\n",
+		       tunnel_id, fd, sock->ops->family, AF_INET);
+		goto err;
+	}
+
+	/* Check if this socket has already been prepped */
+	tunnel = (struct l2tp_tunnel *)sk->sk_user_data;
+	if (tunnel != NULL) {
+		/* This socket has already been prepped */
+		err = -EBUSY;
+		goto err;
+	}
+
+	if (version != L2TP_HDR_VER_2)
+		goto err;
+
+	tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
+	if (tunnel == NULL) {
+		err = -ENOMEM;
+		goto err;
+	}
+
+	tunnel->version = version;
+	tunnel->tunnel_id = tunnel_id;
+	tunnel->peer_tunnel_id = peer_tunnel_id;
+	tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
+
+	tunnel->magic = L2TP_TUNNEL_MAGIC;
+	sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
+	rwlock_init(&tunnel->hlist_lock);
+
+	/* The net we belong to */
+	tunnel->l2tp_net = net;
+	pn = l2tp_pernet(net);
+
+	if (cfg)
+		tunnel->debug = cfg->debug;
+
+	/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
+	udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP;
+	udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv;
+
+	sk->sk_user_data = tunnel;
+
+	/* 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 = &l2tp_tunnel_destruct;
+	tunnel->sock = sk;
+	sk->sk_allocation = GFP_ATOMIC;
+
+	/* Add tunnel to our list */
+	INIT_LIST_HEAD(&tunnel->list);
+	write_lock_bh(&pn->l2tp_tunnel_list_lock);
+	list_add(&tunnel->list, &pn->l2tp_tunnel_list);
+	write_unlock_bh(&pn->l2tp_tunnel_list_lock);
+	atomic_inc(&l2tp_tunnel_count);
+
+	/* Bump the reference count. The tunnel context is deleted
+	 * only when this drops to zero.
+	 */
+	l2tp_tunnel_inc_refcount(tunnel);
+
+	err = 0;
+err:
+	if (tunnelp)
+		*tunnelp = tunnel;
+
+	if (sock)
+		sockfd_put(sock);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
+
+/* Really kill the session.
+ */
+void l2tp_session_free(struct l2tp_session *session)
+{
+	struct l2tp_tunnel *tunnel;
+
+	BUG_ON(atomic_read(&session->ref_count) != 0);
+
+	tunnel = session->tunnel;
+	if (tunnel != NULL) {
+		BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
+
+		/* Delete the session from the hash */
+		write_lock_bh(&tunnel->hlist_lock);
+		hlist_del_init(&session->hlist);
+		write_unlock_bh(&tunnel->hlist_lock);
+
+		if (session->session_id != 0)
+			atomic_dec(&l2tp_session_count);
+
+		sock_put(tunnel->sock);
+
+		/* This will delete the tunnel context if this
+		 * is the last session on the tunnel.
+		 */
+		session->tunnel = NULL;
+		l2tp_tunnel_dec_refcount(tunnel);
+	}
+
+	kfree(session);
+
+	return;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_free);
+
+struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg)
+{
+	struct l2tp_session *session;
+
+	session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
+	if (session != NULL) {
+		session->magic = L2TP_SESSION_MAGIC;
+		session->tunnel = tunnel;
+
+		session->session_id = session_id;
+		session->peer_session_id = peer_session_id;
+
+		sprintf(&session->name[0], "sess %u/%u",
+			tunnel->tunnel_id, session->session_id);
+
+		skb_queue_head_init(&session->reorder_q);
+
+		INIT_HLIST_NODE(&session->hlist);
+
+		/* Inherit debug options from tunnel */
+		session->debug = tunnel->debug;
+
+		if (cfg) {
+			session->debug = cfg->debug;
+			session->hdr_len = cfg->hdr_len;
+			session->mtu = cfg->mtu;
+			session->mru = cfg->mru;
+			session->send_seq = cfg->send_seq;
+			session->recv_seq = cfg->recv_seq;
+			session->lns_mode = cfg->lns_mode;
+		}
+
+		/* Bump the reference count. The session context is deleted
+		 * only when this drops to zero.
+		 */
+		l2tp_session_inc_refcount(session);
+		l2tp_tunnel_inc_refcount(tunnel);
+
+		/* Ensure tunnel socket isn't deleted */
+		sock_hold(tunnel->sock);
+
+		/* Add session to the tunnel's hash list */
+		write_lock_bh(&tunnel->hlist_lock);
+		hlist_add_head(&session->hlist,
+			       l2tp_session_id_hash(tunnel, session_id));
+		write_unlock_bh(&tunnel->hlist_lock);
+
+		/* Ignore management session in session count value */
+		if (session->session_id != 0)
+			atomic_inc(&l2tp_session_count);
+	}
+
+	return session;
+}
+EXPORT_SYMBOL_GPL(l2tp_session_create);
+
+/*****************************************************************************
+ * Init and cleanup
+ *****************************************************************************/
+
+static __net_init int l2tp_init_net(struct net *net)
+{
+	struct l2tp_net *pn;
+	int err;
+
+	pn = kzalloc(sizeof(*pn), GFP_KERNEL);
+	if (!pn)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
+	rwlock_init(&pn->l2tp_tunnel_list_lock);
+
+	err = net_assign_generic(net, l2tp_net_id, pn);
+	if (err)
+		goto out;
+
+	return 0;
+
+out:
+	kfree(pn);
+	return err;
+}
+
+static __net_exit void l2tp_exit_net(struct net *net)
+{
+	struct l2tp_net *pn;
+
+	pn = net_generic(net, l2tp_net_id);
+	/*
+	 * if someone has cached our net then
+	 * further net_generic call will return NULL
+	 */
+	net_assign_generic(net, l2tp_net_id, NULL);
+	kfree(pn);
+}
+
+static struct pernet_operations l2tp_net_ops = {
+	.init = l2tp_init_net,
+	.exit = l2tp_exit_net,
+	.id   = &l2tp_net_id,
+	.size = sizeof(struct l2tp_net),
+};
+
+static int __init l2tp_init(void)
+{
+	int rc = 0;
+
+	rc = register_pernet_device(&l2tp_net_ops);
+	if (rc)
+		goto out;
+
+	printk(KERN_INFO "L2TP core driver, %s\n", L2TP_DRV_VERSION);
+
+out:
+	return rc;
+}
+
+static void __exit l2tp_exit(void)
+{
+	unregister_pernet_device(&l2tp_net_ops);
+}
+
+module_init(l2tp_init);
+module_exit(l2tp_exit);
+
+MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
+MODULE_DESCRIPTION("L2TP core");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(L2TP_DRV_VERSION);
+
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
new file mode 100644
index 000000000000..2efe1a3ada98
--- /dev/null
+++ b/net/l2tp/l2tp_core.h
@@ -0,0 +1,254 @@
+/*
+ * L2TP internal definitions.
+ *
+ * Copyright (c) 2008,2009 Katalix Systems Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _L2TP_CORE_H_
+#define _L2TP_CORE_H_
+
+/* Just some random numbers */
+#define L2TP_TUNNEL_MAGIC	0x42114DDA
+#define L2TP_SESSION_MAGIC	0x0C04EB7D
+
+#define L2TP_HASH_BITS	4
+#define L2TP_HASH_SIZE	(1 << L2TP_HASH_BITS)
+
+/* Debug message categories for the DEBUG socket option */
+enum {
+	L2TP_MSG_DEBUG		= (1 << 0),	/* verbose debug (if
+						 * compiled in) */
+	L2TP_MSG_CONTROL	= (1 << 1),	/* userspace - kernel
+						 * interface */
+	L2TP_MSG_SEQ		= (1 << 2),	/* sequence numbers */
+	L2TP_MSG_DATA		= (1 << 3),	/* data packets */
+};
+
+struct sk_buff;
+
+struct l2tp_stats {
+	u64			tx_packets;
+	u64			tx_bytes;
+	u64			tx_errors;
+	u64			rx_packets;
+	u64			rx_bytes;
+	u64			rx_seq_discards;
+	u64			rx_oos_packets;
+	u64			rx_errors;
+};
+
+struct l2tp_tunnel;
+
+/* Describes a session. Contains information to determine incoming
+ * packets and transmit outgoing ones.
+ */
+struct l2tp_session_cfg {
+	unsigned		data_seq:2;	/* data sequencing level
+						 * 0 => none, 1 => IP only,
+						 * 2 => all
+						 */
+	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			offset;		/* offset to payload */
+	int			reorder_timeout; /* configured reorder timeout
+						  * (in jiffies) */
+	int			mtu;
+	int			mru;
+	int			hdr_len;
+};
+
+struct l2tp_session {
+	int			magic;		/* should be
+						 * L2TP_SESSION_MAGIC */
+
+	struct l2tp_tunnel	*tunnel;	/* back pointer to tunnel
+						 * context */
+	u32			session_id;
+	u32			peer_session_id;
+	u16			nr;		/* session NR state (receive) */
+	u16			ns;		/* session NR state (send) */
+	struct sk_buff_head	reorder_q;	/* receive reorder queue */
+	struct hlist_node	hlist;		/* Hash list node */
+	atomic_t		ref_count;
+
+	char			name[32];	/* for logging */
+	unsigned		data_seq:2;	/* data sequencing level
+						 * 0 => none, 1 => IP only,
+						 * 2 => all
+						 */
+	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) */
+	int			mtu;
+	int			mru;
+	int			hdr_len;
+	struct l2tp_stats	stats;
+
+	void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
+	void (*session_close)(struct l2tp_session *session);
+	void (*ref)(struct l2tp_session *session);
+	void (*deref)(struct l2tp_session *session);
+
+	uint8_t			priv[0];	/* private data */
+};
+
+/* Describes the tunnel. It contains info to track all the associated
+ * sessions so incoming packets can be sorted out
+ */
+struct l2tp_tunnel_cfg {
+	int			debug;		/* bitmask of debug message
+						 * categories */
+};
+
+struct l2tp_tunnel {
+	int			magic;		/* Should be L2TP_TUNNEL_MAGIC */
+	rwlock_t		hlist_lock;	/* protect session_hlist */
+	struct hlist_head	session_hlist[L2TP_HASH_SIZE];
+						/* hashed list of sessions,
+						 * hashed by id */
+	u32			tunnel_id;
+	u32			peer_tunnel_id;
+	int			version;	/* 2=>L2TPv2, 3=>L2TPv3 */
+
+	char			name[20];	/* for logging */
+	int			debug;		/* bitmask of debug message
+						 * categories */
+	int			hdr_len;
+	struct l2tp_stats	stats;
+
+	struct list_head	list;		/* Keep a list of all tunnels */
+	struct net		*l2tp_net;	/* the net we belong to */
+
+	atomic_t		ref_count;
+
+	int (*recv_payload_hook)(struct sk_buff *skb);
+	void (*old_sk_destruct)(struct sock *);
+	struct sock		*sock;		/* Parent socket */
+	int			fd;
+
+	uint8_t			priv[0];	/* private data */
+};
+
+static inline void *l2tp_tunnel_priv(struct l2tp_tunnel *tunnel)
+{
+	return &tunnel->priv[0];
+}
+
+static inline void *l2tp_session_priv(struct l2tp_session *session)
+{
+	return &session->priv[0];
+}
+
+static inline struct l2tp_tunnel *l2tp_sock_to_tunnel(struct sock *sk)
+{
+	struct l2tp_tunnel *tunnel;
+
+	if (sk == NULL)
+		return NULL;
+
+	sock_hold(sk);
+	tunnel = (struct l2tp_tunnel *)(sk->sk_user_data);
+	if (tunnel == NULL) {
+		sock_put(sk);
+		goto out;
+	}
+
+	BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
+
+out:
+	return tunnel;
+}
+
+extern struct l2tp_session *l2tp_session_find(struct l2tp_tunnel *tunnel, u32 session_id);
+extern struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth);
+extern struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id);
+extern struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth);
+
+extern int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp);
+extern struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg);
+extern void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
+extern void l2tp_session_free(struct l2tp_session *session);
+extern int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb, int (*payload_hook)(struct sk_buff *skb));
+extern int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
+
+extern void l2tp_build_l2tp_header(struct l2tp_session *session, void *buf);
+extern int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, size_t data_len);
+extern int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len);
+extern void l2tp_tunnel_destruct(struct sock *sk);
+extern void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
+
+/* Tunnel reference counts. Incremented per session that is added to
+ * the tunnel.
+ */
+static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
+{
+	atomic_inc(&tunnel->ref_count);
+}
+
+static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
+{
+	if (atomic_dec_and_test(&tunnel->ref_count))
+		l2tp_tunnel_free(tunnel);
+}
+#ifdef L2TP_REFCNT_DEBUG
+#define l2tp_tunnel_inc_refcount(_t) do { \
+		printk(KERN_DEBUG "l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_t)->name, atomic_read(&_t->ref_count)); \
+		l2tp_tunnel_inc_refcount_1(_t);				\
+	} while (0)
+#define l2tp_tunnel_dec_refcount(_t) do { \
+		printk(KERN_DEBUG "l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_t)->name, atomic_read(&_t->ref_count)); \
+		l2tp_tunnel_dec_refcount_1(_t);				\
+	} while (0)
+#else
+#define l2tp_tunnel_inc_refcount(t) l2tp_tunnel_inc_refcount_1(t)
+#define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t)
+#endif
+
+/* Session reference counts. Incremented when code obtains a reference
+ * to a session.
+ */
+static inline void l2tp_session_inc_refcount_1(struct l2tp_session *session)
+{
+	atomic_inc(&session->ref_count);
+}
+
+static inline void l2tp_session_dec_refcount_1(struct l2tp_session *session)
+{
+	if (atomic_dec_and_test(&session->ref_count))
+		l2tp_session_free(session);
+}
+
+#ifdef L2TP_REFCNT_DEBUG
+#define l2tp_session_inc_refcount(_s) do { \
+		printk(KERN_DEBUG "l2tp_session_inc_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_s)->name, atomic_read(&_s->ref_count)); \
+		l2tp_session_inc_refcount_1(_s);				\
+	} while (0)
+#define l2tp_session_dec_refcount(_s) do { \
+		printk(KERN_DEBUG "l2tp_session_dec_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_s)->name, atomic_read(&_s->ref_count)); \
+		l2tp_session_dec_refcount_1(_s);				\
+	} while (0)
+#else
+#define l2tp_session_inc_refcount(s) l2tp_session_inc_refcount_1(s)
+#define l2tp_session_dec_refcount(s) l2tp_session_dec_refcount_1(s)
+#endif
+
+#endif /* _L2TP_CORE_H_ */
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
new file mode 100644
index 000000000000..baac072761aa
--- /dev/null
+++ b/net/l2tp/l2tp_ppp.c
@@ -0,0 +1,1658 @@
+/*****************************************************************************
+ * Linux PPP over L2TP (PPPoX/PPPoL2TP) Sockets
+ *
+ * PPPoX    --- Generic PPP encapsulation socket family
+ * PPPoL2TP --- PPP over L2TP (RFC 2661)
+ *
+ * Version:	2.0.0
+ *
+ * Authors:	James Chapman (jchapman@katalix.com)
+ *
+ * Based on original work by Martijn van Oosterhout <kleptog@svana.org>
+ *
+ * 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 <linux/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>
+
+#include "l2tp_core.h"
+
+#define PPPOL2TP_DRV_VERSION	"V2.0"
+
+/* Space for UDP, L2TP and PPP headers */
+#define PPPOL2TP_HEADER_OVERHEAD	40
+
+#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
+
+/* Private data of each session. This data lives at the end of struct
+ * l2tp_session, referenced via session->priv[].
+ */
+struct pppol2tp_session {
+	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 */
+	int			flags;		/* accessed by PPPIOCGFLAGS.
+						 * Unused. */
+};
+
+static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb);
+
+static struct ppp_channel_ops pppol2tp_chan_ops = { pppol2tp_xmit , NULL };
+static const struct proto_ops pppol2tp_ops;
+
+/* Helpers to obtain tunnel/session contexts from sockets.
+ */
+static inline struct l2tp_session *pppol2tp_sock_to_session(struct sock *sk)
+{
+	struct l2tp_session *session;
+
+	if (sk == NULL)
+		return NULL;
+
+	sock_hold(sk);
+	session = (struct l2tp_session *)(sk->sk_user_data);
+	if (session == NULL) {
+		sock_put(sk);
+		goto out;
+	}
+
+	BUG_ON(session->magic != L2TP_SESSION_MAGIC);
+
+out:
+	return session;
+}
+
+/*****************************************************************************
+ * Receive data handling
+ *****************************************************************************/
+
+static int pppol2tp_recv_payload_hook(struct sk_buff *skb)
+{
+	/* 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))
+		return 1;
+
+	if ((skb->data[0] == 0xff) && (skb->data[1] == 0x03))
+		skb_pull(skb, 2);
+
+	return 0;
+}
+
+/* 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;
+}
+
+static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len)
+{
+	struct pppol2tp_session *ps = l2tp_session_priv(session);
+	struct sock *sk = NULL;
+
+	/* If the socket is bound, send it in to PPP's input queue. Otherwise
+	 * queue it on the session socket.
+	 */
+	sk = ps->sock;
+	if (sk == NULL)
+		goto no_sock;
+
+	if (sk->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, data_len);
+
+		/* 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(sk);
+		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);
+	}
+
+	return;
+
+no_sock:
+	PRINTK(session->debug, PPPOL2TP_MSG_DATA, KERN_INFO,
+	       "%s: no socket\n", session->name);
+	kfree_skb(skb);
+}
+
+static void pppol2tp_session_sock_hold(struct l2tp_session *session)
+{
+	struct pppol2tp_session *ps = l2tp_session_priv(session);
+
+	if (ps->sock)
+		sock_hold(ps->sock);
+}
+
+static void pppol2tp_session_sock_put(struct l2tp_session *session)
+{
+	struct pppol2tp_session *ps = l2tp_session_priv(session);
+
+	if (ps->sock)
+		sock_put(ps->sock);
+}
+
+/************************************************************************
+ * 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 l2tp_session *session)
+{
+	if (session->send_seq)
+		return PPPOL2TP_L2TP_HDR_SIZE_SEQ;
+
+	return PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
+}
+
+/* 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 sk_buff *skb;
+	int error;
+	struct l2tp_session *session;
+	struct l2tp_tunnel *tunnel;
+	struct pppol2tp_session *ps;
+
+	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;
+
+	ps = l2tp_session_priv(session);
+	tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
+	if (tunnel == NULL)
+		goto error_put_sess;
+
+	/* Allocate a socket buffer */
+	error = -ENOMEM;
+	skb = sock_wmalloc(sk, NET_SKB_PAD + sizeof(struct iphdr) +
+			   sizeof(struct udphdr) + session->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);
+	skb_reserve(skb, sizeof(struct udphdr));
+
+	/* 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);
+
+	l2tp_xmit_skb(session, skb, session->hdr_len);
+
+	sock_put(ps->tunnel_sock);
+
+	return error;
+
+error_put_sess_tun:
+	sock_put(ps->tunnel_sock);
+error_put_sess:
+	sock_put(sk);
+error:
+	return error;
+}
+
+/* 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;
+	struct l2tp_session *session;
+	struct l2tp_tunnel *tunnel;
+	struct pppol2tp_session *ps;
+	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;
+
+	ps = l2tp_session_priv(session);
+	sk_tun = ps->tunnel_sock;
+	if (sk_tun == NULL)
+		goto abort_put_sess;
+	tunnel = l2tp_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);
+
+	old_headroom = skb_headroom(skb);
+	if (skb_cow_head(skb, sizeof(ppph)))
+		goto abort_put_sess_tun;
+
+	new_headroom = skb_headroom(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];
+
+	l2tp_xmit_skb(session, skb, hdr_len);
+
+	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.
+ *****************************************************************************/
+
+/* Called by l2tp_core when a session socket is being closed.
+ */
+static void pppol2tp_session_close(struct l2tp_session *session)
+{
+	struct pppol2tp_session *ps = l2tp_session_priv(session);
+	struct sock *sk = ps->sock;
+	struct sk_buff *skb;
+
+	BUG_ON(session->magic != L2TP_SESSION_MAGIC);
+
+	if (session->session_id == 0)
+		goto out;
+
+	if (sk != NULL) {
+		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);
+	}
+
+out:
+	return;
+}
+
+/* Really kill the session socket. (Called from sock_put() if
+ * refcnt == 0.)
+ */
+static void pppol2tp_session_destruct(struct sock *sk)
+{
+	struct l2tp_session *session;
+
+	if (sk->sk_user_data != NULL) {
+		session = sk->sk_user_data;
+		if (session == NULL)
+			goto out;
+
+		sk->sk_user_data = NULL;
+		BUG_ON(session->magic != L2TP_SESSION_MAGIC);
+		l2tp_session_dec_refcount(session);
+	}
+
+out:
+	return;
+}
+
+/* Called when the PPPoX socket (session) is closed.
+ */
+static int pppol2tp_release(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	struct l2tp_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;
+}
+
+static struct proto pppol2tp_sk_proto = {
+	.name	  = "PPPOL2TP",
+	.owner	  = THIS_MODULE,
+	.obj_size = sizeof(struct pppox_sock),
+};
+
+static int pppol2tp_backlog_recv(struct sock *sk, struct sk_buff *skb)
+{
+	int rc;
+
+	rc = l2tp_udp_encap_recv(sk, skb);
+	if (rc)
+		kfree_skb(skb);
+
+	return NET_RX_SUCCESS;
+}
+
+/* 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_backlog_recv;
+	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 l2tp_session *session = NULL;
+	struct l2tp_tunnel *tunnel;
+	struct pppol2tp_session *ps;
+	struct dst_entry *dst;
+	struct l2tp_session_cfg cfg = { 0, };
+	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: create tunnel context 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)) {
+		error = l2tp_tunnel_create(sock_net(sk), sp->pppol2tp.fd, 2, sp->pppol2tp.s_tunnel, sp->pppol2tp.d_tunnel, NULL, &tunnel);
+		if (error < 0)
+			goto end;
+	} else {
+		tunnel = l2tp_tunnel_find(sock_net(sk), sp->pppol2tp.s_tunnel);
+
+		/* Error if we can't find the tunnel */
+		error = -ENOENT;
+		if (tunnel == NULL)
+			goto end;
+
+		/* Error if socket is not prepped */
+		if (tunnel->sock == NULL)
+			goto end;
+	}
+
+	if (tunnel->recv_payload_hook == NULL)
+		tunnel->recv_payload_hook = pppol2tp_recv_payload_hook;
+
+	/* Check that this session doesn't already exist */
+	error = -EEXIST;
+	session = l2tp_session_find(tunnel, sp->pppol2tp.s_session);
+	if (session != NULL)
+		goto end;
+
+	/* Default MTU must allow space for UDP/L2TP/PPP
+	 * headers.
+	 */
+	cfg.mtu = cfg.mru = 1500 - PPPOL2TP_HEADER_OVERHEAD;
+	cfg.hdr_len = PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
+	cfg.debug = tunnel->debug;
+
+	/* Allocate and initialize a new session context. */
+	session = l2tp_session_create(sizeof(struct pppol2tp_session),
+				      tunnel, sp->pppol2tp.s_session,
+				      sp->pppol2tp.d_session, &cfg);
+	if (session == NULL) {
+		error = -ENOMEM;
+		goto end;
+	}
+
+	ps = l2tp_session_priv(session);
+	ps->owner	     = current->pid;
+	ps->sock	     = sk;
+	ps->tunnel_sock = tunnel->sock;
+
+	session->recv_skb	= pppol2tp_recv;
+	session->session_close	= pppol2tp_session_close;
+
+	/* We need to know each time a skb is dropped from the reorder
+	 * queue.
+	 */
+	session->ref = pppol2tp_session_sock_hold;
+	session->deref = pppol2tp_session_sock_put;
+
+	/* 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. Just set up
+	 * the internal context for use by ioctl() and sockopt()
+	 * handlers.
+	 */
+	if ((session->session_id == 0) &&
+	    (session->peer_session_id == 0)) {
+		error = 0;
+		goto out_no_ppp;
+	}
+
+	/* 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;
+
+out_no_ppp:
+	/* This is how we get the session context from the socket. */
+	sk->sk_user_data = session;
+	sk->sk_state = PPPOX_CONNECTED;
+	PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+	       "%s: created\n", session->name);
+
+end:
+	release_sock(sk);
+
+	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 l2tp_session *session;
+	struct l2tp_tunnel *tunnel;
+	struct sock *sk = sock->sk;
+	struct inet_sock *inet;
+	struct pppol2tp_session *pls;
+
+	error = -ENOTCONN;
+	if (sk == NULL)
+		goto end;
+	if (sk->sk_state != PPPOX_CONNECTED)
+		goto end;
+
+	error = -EBADF;
+	session = pppol2tp_sock_to_session(sk);
+	if (session == NULL)
+		goto end;
+
+	pls = l2tp_session_priv(session);
+	tunnel = l2tp_sock_to_tunnel(pls->tunnel_sock);
+	if (tunnel == NULL) {
+		error = -EBADF;
+		goto end_put_sess;
+	}
+
+	memset(&sp, 0, len);
+	sp.sa_family	= AF_PPPOX;
+	sp.sa_protocol	= PX_PROTO_OL2TP;
+	sp.pppol2tp.fd  = tunnel->fd;
+	sp.pppol2tp.pid = pls->owner;
+	sp.pppol2tp.s_tunnel = tunnel->tunnel_id;
+	sp.pppol2tp.d_tunnel = tunnel->peer_tunnel_id;
+	sp.pppol2tp.s_session = session->session_id;
+	sp.pppol2tp.d_session = session->peer_session_id;
+	inet = inet_sk(sk);
+	sp.pppol2tp.addr.sin_family = AF_INET;
+	sp.pppol2tp.addr.sin_port = inet->inet_dport;
+	sp.pppol2tp.addr.sin_addr.s_addr = inet->inet_daddr;
+
+	memcpy(uaddr, &sp, len);
+
+	*usockaddr_len = len;
+
+	sock_put(pls->tunnel_sock);
+end_put_sess:
+	sock_put(sk);
+	error = 0;
+
+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.
+ ****************************************************************************/
+
+static void pppol2tp_copy_stats(struct pppol2tp_ioc_stats *dest,
+				struct l2tp_stats *stats)
+{
+	dest->tx_packets = stats->tx_packets;
+	dest->tx_bytes = stats->tx_bytes;
+	dest->tx_errors = stats->tx_errors;
+	dest->rx_packets = stats->rx_packets;
+	dest->rx_bytes = stats->rx_bytes;
+	dest->rx_seq_discards = stats->rx_seq_discards;
+	dest->rx_oos_packets = stats->rx_oos_packets;
+	dest->rx_errors = stats->rx_errors;
+}
+
+/* Session ioctl helper.
+ */
+static int pppol2tp_session_ioctl(struct l2tp_session *session,
+				  unsigned int cmd, unsigned long arg)
+{
+	struct ifreq ifr;
+	int err = 0;
+	struct sock *sk;
+	int val = (int) arg;
+	struct pppol2tp_session *ps = l2tp_session_priv(session);
+	struct l2tp_tunnel *tunnel = session->tunnel;
+	struct pppol2tp_ioc_stats stats;
+
+	PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_DEBUG,
+	       "%s: pppol2tp_session_ioctl(cmd=%#x, arg=%#lx)\n",
+	       session->name, cmd, arg);
+
+	sk = ps->sock;
+	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(ps->flags, (int __user *) arg))
+			break;
+
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: get flags=%d\n", session->name, ps->flags);
+		err = 0;
+		break;
+
+	case PPPIOCSFLAGS:
+		err = -EFAULT;
+		if (get_user(val, (int __user *) arg))
+			break;
+		ps->flags = val;
+		PRINTK(session->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
+		       "%s: set flags=%d\n", session->name, ps->flags);
+		err = 0;
+		break;
+
+	case PPPIOCGL2TPSTATS:
+		err = -ENXIO;
+		if (!(sk->sk_state & PPPOX_CONNECTED))
+			break;
+
+		memset(&stats, 0, sizeof(stats));
+		stats.tunnel_id = tunnel->tunnel_id;
+		stats.session_id = session->session_id;
+		pppol2tp_copy_stats(&stats, &session->stats);
+		if (copy_to_user((void __user *) arg, &stats,
+				 sizeof(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 l2tp_tunnel *tunnel,
+				 unsigned int cmd, unsigned long arg)
+{
+	int err = 0;
+	struct sock *sk;
+	struct pppol2tp_ioc_stats stats;
+
+	PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_DEBUG,
+	       "%s: pppol2tp_tunnel_ioctl(cmd=%#x, arg=%#lx)\n",
+	       tunnel->name, cmd, arg);
+
+	sk = tunnel->sock;
+	sock_hold(sk);
+
+	switch (cmd) {
+	case PPPIOCGL2TPSTATS:
+		err = -ENXIO;
+		if (!(sk->sk_state & PPPOX_CONNECTED))
+			break;
+
+		if (copy_from_user(&stats, (void __user *) arg,
+				   sizeof(stats))) {
+			err = -EFAULT;
+			break;
+		}
+		if (stats.session_id != 0) {
+			/* resend to session ioctl handler */
+			struct l2tp_session *session =
+				l2tp_session_find(tunnel, stats.session_id);
+			if (session != NULL)
+				err = pppol2tp_session_ioctl(session, cmd, arg);
+			else
+				err = -EBADR;
+			break;
+		}
+#ifdef CONFIG_XFRM
+		stats.using_ipsec = (sk->sk_policy[0] || sk->sk_policy[1]) ? 1 : 0;
+#endif
+		pppol2tp_copy_stats(&stats, &tunnel->stats);
+		if (copy_to_user((void __user *) arg, &stats, sizeof(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 l2tp_session *session;
+	struct l2tp_tunnel *tunnel;
+	struct pppol2tp_session *ps;
+	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
+	 */
+	ps = l2tp_session_priv(session);
+	if ((session->session_id == 0) &&
+	    (session->peer_session_id == 0)) {
+		err = -EBADF;
+		tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
+		if (tunnel == NULL)
+			goto end_put_sess;
+
+		err = pppol2tp_tunnel_ioctl(tunnel, cmd, arg);
+		sock_put(ps->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 l2tp_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 l2tp_session *session,
+				       int optname, int val)
+{
+	int err = 0;
+	struct pppol2tp_session *ps = l2tp_session_priv(session);
+
+	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      = ps->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 l2tp_session *session;
+	struct l2tp_tunnel *tunnel;
+	struct pppol2tp_session *ps;
+	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
+	 */
+	ps = l2tp_session_priv(session);
+	if ((session->session_id == 0) &&
+	    (session->peer_session_id == 0)) {
+		err = -EBADF;
+		tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
+		if (tunnel == NULL)
+			goto end_put_sess;
+
+		err = pppol2tp_tunnel_setsockopt(sk, tunnel, optname, val);
+		sock_put(ps->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 l2tp_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 l2tp_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 l2tp_session *session;
+	struct l2tp_tunnel *tunnel;
+	int val, len;
+	int err;
+	struct pppol2tp_session *ps;
+
+	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 */
+	ps = l2tp_session_priv(session);
+	if ((session->session_id == 0) &&
+	    (session->peer_session_id == 0)) {
+		err = -EBADF;
+		tunnel = l2tp_sock_to_tunnel(ps->tunnel_sock);
+		if (tunnel == NULL)
+			goto end_put_sess;
+
+		err = pppol2tp_tunnel_getsockopt(sk, tunnel, optname, &val);
+		sock_put(ps->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
+ *****************************************************************************/
+
+static unsigned int pppol2tp_net_id;
+
+#ifdef CONFIG_PROC_FS
+
+struct pppol2tp_seq_data {
+	struct seq_net_private p;
+	int tunnel_idx;			/* current tunnel */
+	int session_idx;		/* index of session within current tunnel */
+	struct l2tp_tunnel *tunnel;
+	struct l2tp_session *session;	/* NULL means get next tunnel */
+};
+
+static void pppol2tp_next_tunnel(struct net *net, struct pppol2tp_seq_data *pd)
+{
+	pd->tunnel = l2tp_tunnel_find_nth(net, pd->tunnel_idx);
+	pd->tunnel_idx++;
+}
+
+static void pppol2tp_next_session(struct net *net, struct pppol2tp_seq_data *pd)
+{
+	pd->session = l2tp_session_find_nth(pd->tunnel, pd->session_idx);
+	pd->session_idx++;
+	if (pd->session == NULL) {
+		pd->session_idx = 0;
+		pppol2tp_next_tunnel(net, pd);
+	}
+}
+
+static void *pppol2tp_seq_start(struct seq_file *m, loff_t *offs)
+{
+	struct pppol2tp_seq_data *pd = SEQ_START_TOKEN;
+	loff_t pos = *offs;
+	struct net *net;
+
+	if (!pos)
+		goto out;
+
+	BUG_ON(m->private == NULL);
+	pd = m->private;
+	net = seq_file_net(m);
+
+	if (pd->tunnel == NULL)
+		pppol2tp_next_tunnel(net, pd);
+	else
+		pppol2tp_next_session(net, pd);
+
+	/* 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 l2tp_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 l2tp_session *session = v;
+	struct l2tp_tunnel *tunnel = session->tunnel;
+	struct pppol2tp_session *ps = l2tp_session_priv(session);
+	u32 ip = 0;
+	u16 port = 0;
+
+	if (tunnel->sock) {
+		struct inet_sock *inet = inet_sk(tunnel->sock);
+		ip = ntohl(inet->inet_saddr);
+		port = ntohs(inet->inet_sport);
+	}
+
+	seq_printf(m, "  SESSION '%s' %08X/%d %04X/%04X -> "
+		   "%04X/%04X %d %c\n",
+		   session->name, ip, port,
+		   tunnel->tunnel_id,
+		   session->session_id,
+		   tunnel->peer_tunnel_id,
+		   session->peer_session_id,
+		   ps->sock->sk_state,
+		   (session == ps->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 */
+
+/*****************************************************************************
+ * Network namespace
+ *****************************************************************************/
+
+static __net_init int pppol2tp_init_net(struct net *net)
+{
+	struct proc_dir_entry *pde;
+	int err = 0;
+
+	pde = proc_net_fops_create(net, "pppol2tp", S_IRUGO, &pppol2tp_proc_fops);
+	if (!pde) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+out:
+	return err;
+}
+
+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,
+};
+
+/*****************************************************************************
+ * 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 int __init pppol2tp_init(void)
+{
+	int err;
+
+	err = register_pernet_device(&pppol2tp_net_ops);
+	if (err)
+		goto out;
+
+	err = proto_register(&pppol2tp_sk_proto, 0);
+	if (err)
+		goto out_unregister_pppol2tp_pernet;
+
+	err = register_pppox_proto(PX_PROTO_OL2TP, &pppol2tp_proto);
+	if (err)
+		goto out_unregister_pppol2tp_proto;
+
+	printk(KERN_INFO "PPPoL2TP kernel driver, %s\n",
+	       PPPOL2TP_DRV_VERSION);
+
+out:
+	return err;
+out_unregister_pppol2tp_proto:
+	proto_unregister(&pppol2tp_sk_proto);
+out_unregister_pppol2tp_pernet:
+	unregister_pernet_device(&pppol2tp_net_ops);
+	goto out;
+}
+
+static void __exit pppol2tp_exit(void)
+{
+	unregister_pppox_proto(PX_PROTO_OL2TP);
+	proto_unregister(&pppol2tp_sk_proto);
+	unregister_pernet_device(&pppol2tp_net_ops);
+}
+
+module_init(pppol2tp_init);
+module_exit(pppol2tp_exit);
+
+MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
+MODULE_DESCRIPTION("PPP over L2TP over UDP");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(PPPOL2TP_DRV_VERSION);
diff --git a/net/l2tp/pppol2tp.c b/net/l2tp/pppol2tp.c
deleted file mode 100644
index 449a9825200d..000000000000
--- a/net/l2tp/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);