l2tp: Split pppol2tp patch into separate l2tp and ppp parts
James Chapman [Fri, 2 Apr 2010 06:18:33 +0000 (06:18 +0000)]
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>

drivers/net/Kconfig
include/linux/if_pppol2tp.h
net/Kconfig
net/Makefile
net/l2tp/Kconfig [new file with mode: 0644]
net/l2tp/Makefile
net/l2tp/l2tp_core.c [new file with mode: 0644]
net/l2tp/l2tp_core.h [new file with mode: 0644]
net/l2tp/l2tp_ppp.c [new file with mode: 0644]
net/l2tp/pppol2tp.c [deleted file]

index 2cffcb8..a55bff2 100644 (file)
@@ -3158,17 +3158,12 @@ config PPPOATM
 
 config PPPOL2TP
        tristate "PPP over L2TP (EXPERIMENTAL)"
-       depends on EXPERIMENTAL && PPP && INET
+       depends on EXPERIMENTAL && L2TP && PPP
        help
          Support for PPP-over-L2TP socket family. L2TP is a protocol
          used by ISPs and enterprises to tunnel PPP traffic over UDP
          tunnels. L2TP is replacing PPTP for VPN uses.
 
-         This 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.sourceforge.net/).
-
 config SLIP
        tristate "SLIP (serial line) support"
        ---help---
index c58baea..1a1fb6e 100644 (file)
@@ -2,7 +2,7 @@
  * Linux PPP over L2TP (PPPoL2TP) Socket Implementation (RFC 2661)
  *
  * This file supplies definitions required by the PPP over L2TP driver
- * (pppol2tp.c).  All version information wrt this file is located in pppol2tp.c
+ * (l2tp_ppp.c).  All version information wrt this file is located in l2tp_ppp.c
  *
  * License:
  *             This program is free software; you can redistribute it and/or
index e10d55c..0d68b40 100644 (file)
@@ -186,6 +186,7 @@ source "net/sctp/Kconfig"
 source "net/rds/Kconfig"
 source "net/tipc/Kconfig"
 source "net/atm/Kconfig"
+source "net/l2tp/Kconfig"
 source "net/802/Kconfig"
 source "net/bridge/Kconfig"
 source "net/dsa/Kconfig"
index 13ca77e..cb7bdc1 100644 (file)
@@ -40,7 +40,7 @@ obj-$(CONFIG_BT)              += bluetooth/
 obj-$(CONFIG_SUNRPC)           += sunrpc/
 obj-$(CONFIG_AF_RXRPC)         += rxrpc/
 obj-$(CONFIG_ATM)              += atm/
-obj-$(CONFIG_PPPOL2TP)         += l2tp/
+obj-$(CONFIG_L2TP)             += l2tp/
 obj-$(CONFIG_DECNET)           += decnet/
 obj-$(CONFIG_ECONET)           += econet/
 obj-$(CONFIG_PHONET)           += phonet/
diff --git a/net/l2tp/Kconfig b/net/l2tp/Kconfig
new file mode 100644 (file)
index 0000000..ec88c5c
--- /dev/null
@@ -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.
index 9af41e8..c91f208 100644 (file)
@@ -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 (file)
index 0000000..4b6da36
--- /dev/null
@@ -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 (file)
index 0000000..2efe1a3
--- /dev/null
@@ -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 (file)
index 0000000..baac072
--- /dev/null
@@ -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 (file)
index 449a982..0000000
+++ /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);