Logo Search packages:      
Sourcecode: linux version File versions  Download package

pppol2tp.c

/*****************************************************************************
 * 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/version.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 <net/net_namespace.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 */

      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 struct proto_ops pppol2tp_ops;
static LIST_HEAD(pppol2tp_tunnel_list);
static DEFINE_RWLOCK(pppol2tp_tunnel_list_lock);

/* 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;

      session = (struct pppol2tp_session *)(sk->sk_user_data);
      if (session == NULL)
            return NULL;

      BUG_ON(session->magic != L2TP_SESSION_MAGIC);

      return session;
}

static inline struct pppol2tp_tunnel *pppol2tp_sock_to_tunnel(struct sock *sk)
{
      struct pppol2tp_tunnel *tunnel;

      if (sk == NULL)
            return NULL;

      tunnel = (struct pppol2tp_tunnel *)(sk->sk_user_data);
      if (tunnel == NULL)
            return NULL;

      BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);

      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(&tunnel->hlist_lock);
      hlist_for_each_entry(session, walk, session_list, hlist) {
            if (session->tunnel_addr.s_session == session_id) {
                  read_unlock(&tunnel->hlist_lock);
                  return session;
            }
      }
      read_unlock(&tunnel->hlist_lock);

      return NULL;
}

/* Lookup a tunnel by id
 */
static struct pppol2tp_tunnel *pppol2tp_tunnel_find(u16 tunnel_id)
{
      struct pppol2tp_tunnel *tunnel = NULL;

      read_lock(&pppol2tp_tunnel_list_lock);
      list_for_each_entry(tunnel, &pppol2tp_tunnel_list, list) {
            if (tunnel->stats.tunnel_id == tunnel_id) {
                  read_unlock(&pppol2tp_tunnel_list_lock);
                  return tunnel;
            }
      }
      read_unlock(&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;
      u16 ns = PPPOL2TP_SKB_CB(skb)->ns;

      spin_lock(&session->reorder_q.lock);
      skb_queue_walk(&session->reorder_q, skbp) {
            if (PPPOL2TP_SKB_CB(skbp)->ns > ns) {
                  __skb_insert(skb, skbp->prev, skbp, &session->reorder_q);
                  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(&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 unlink it and return resources
       * to its current owner (a socket receive buffer).
       */
      skb_unlink(skb, &session->reorder_q);
      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);
            dst_release(skb->dst);
            skb->dst = NULL;
            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(&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);
                  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;
                  }
            }
            spin_unlock(&session->reorder_q.lock);
            pppol2tp_recv_dequeue_skb(session, skb);
            spin_lock(&session->reorder_q.lock);
      }

out:
      spin_unlock(&session->reorder_q.lock);
}

/* 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;

      /* 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);

      return 0;

discard:
      session->stats.rx_errors++;
      kfree_skb(skb);
      sock_put(session->sock);

      return 0;

error:
      /* Put UDP header back */
      __skb_push(skb, sizeof(struct udphdr));

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;

      return 0;

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) {
            err = memcpy_toiovec(msg->msg_iov, (unsigned char *) skb->data,
                             skb->len);
            if (err < 0)
                  goto do_skb_free;
            err = skb->len;
      }
do_skb_free:
      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 = 0;
      struct sk_buff *skb;
      int error;
      int hdr_len;
      struct pppol2tp_session *session;
      struct pppol2tp_tunnel *tunnel;
      struct udphdr *uh;
      unsigned int 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;

      tunnel = pppol2tp_sock_to_tunnel(session->tunnel_sock);
      if (tunnel == NULL)
            goto error;

      /* 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;

      /* 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(session->tunnel_sock);
      uh = (struct udphdr *) skb->data;
      uh->source = inet->sport;
      uh->dest = inet->dport;
      uh->len = htons(hdr_len + sizeof(ppph) + total_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;
      }
      skb_put(skb, total_len);

      /* Calculate UDP checksum if configured to do so */
      if (session->tunnel_sock->sk_no_check != UDP_CSUM_NOXMIT)
            csum = udp_csum_outgoing(sk, skb);

      /* 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++;
      }

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 pppol2tp_session *session;
      struct pppol2tp_tunnel *tunnel;
      int rc;
      int headroom;
      int data_len = skb->len;
      struct inet_sock *inet;
      __wsum csum = 0;
      struct udphdr *uh;
      unsigned int len;

      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;
      tunnel = pppol2tp_sock_to_tunnel(sk_tun);
      if (tunnel == NULL)
            goto abort;

      /* 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. Note that a new skb (or a clone) is
       * allocated. If we return an error from this point on, make
       * sure we free the new skb but do not free the original skb
       * since that is done by the caller for the error case.
       */
      headroom = NET_SKB_PAD + sizeof(struct iphdr) +
            sizeof(struct udphdr) + hdr_len + sizeof(ppph);
      if (skb_cow_head(skb, headroom))
            goto abort;

      /* 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));

      /* 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->sport;
      uh->dest = inet->dport;
      uh->len = htons(sizeof(struct udphdr) + hdr_len + sizeof(ppph) + data_len);
      uh->check = 0;

      /* *BROKEN* Calculate UDP checksum if configured to do so */
      if (sk_tun->sk_no_check != UDP_CSUM_NOXMIT)
            csum = udp_csum_outgoing(sk_tun, skb);

      /* 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 */
      dst_release(skb->dst);
      skb->dst = sk_dst_get(sk_tun);
      skb_orphan(skb);
      skb->sk = sk_tun;

      /* 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++;
      }

      return 1;

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;

      if (tunnel == NULL)
            BUG();

      PRINTK(tunnel->debug, PPPOL2TP_MSG_CONTROL, KERN_INFO,
             "%s: closing all sessions...\n", tunnel->name);

      write_lock(&tunnel->hlist_lock);
      for (hash = 0; hash < PPPOL2TP_HASH_SIZE; hash++) {
again:
            hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
                  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(&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);
                  skb_queue_purge(&session->reorder_q);

                  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(&tunnel->hlist_lock);
                  goto again;
            }
      }
      write_unlock(&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)
{
      /* Remove from socket list */
      write_lock(&pppol2tp_tunnel_list_lock);
      list_del_init(&tunnel->list);
      write_unlock(&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 = pppol2tp_sock_to_tunnel(sk);
      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 = pppol2tp_sock_to_session(sk);
            if (session == NULL)
                  goto out;

            /* 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(&tunnel->hlist_lock);
                        hlist_del_init(&session->hlist);
                        write_unlock(&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;
      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;

      /* Purge any queued data */
      skb_queue_purge(&sk->sk_receive_queue);
      skb_queue_purge(&sk->sk_write_queue);

      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(int fd, u16 tunnel_id,
                                       int *error)
{
      int err;
      struct socket *sock = NULL;
      struct sock *sk;
      struct pppol2tp_tunnel *tunnel;
      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);

      /* Add tunnel to our list */
      INIT_LIST_HEAD(&tunnel->list);
      write_lock(&pppol2tp_tunnel_list_lock);
      list_add(&tunnel->list, &pppol2tp_tunnel_list);
      write_unlock(&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(sp->pppol2tp.fd,
                                               sp->pppol2tp.s_tunnel,
                                               &error);
            if (tunnel_sock == NULL)
                  goto end;

            tunnel = tunnel_sock->sk_user_data;
      } else {
            tunnel = pppol2tp_tunnel_find(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_channel(&po->chan);
      if (error)
            goto end;

      /* 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(&tunnel->hlist_lock);
      hlist_add_head(&session->hlist,
                   pppol2tp_session_id_hash(tunnel,
                                    session->tunnel_addr.s_session));
      write_unlock(&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:
      release_sock(sk);

      if (error != 0)
            PRINTK(session ? session->debug : -1, PPPOL2TP_MSG_CONTROL, KERN_WARNING,
                   "%s: connect failed: %d\n", session->name, 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;

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;

            err = pppol2tp_tunnel_ioctl(tunnel, cmd, arg);
            goto end;
      }

      err = pppol2tp_session_ioctl(session, cmd, arg);

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, 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;

            err = pppol2tp_tunnel_setsockopt(sk, tunnel, optname, val);
      } else
            err = pppol2tp_session_setsockopt(sk, session, optname, val);

      err = 0;

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;

            err = pppol2tp_tunnel_getsockopt(sk, tunnel, optname, &val);
      } else
            err = pppol2tp_session_getsockopt(sk, session, optname, &val);

      err = -EFAULT;
      if (put_user(len, (int __user *) optlen))
            goto end;

      if (copy_to_user((void __user *) optval, &val, len))
            goto end;

      err = 0;
end:
      return err;
}

/*****************************************************************************
 * /proc filesystem for debug
 *****************************************************************************/

#ifdef CONFIG_PROC_FS

#include <linux/seq_file.h>

struct pppol2tp_seq_data {
      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(&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(&tunnel->hlist_lock);
      if (!found)
            session = NULL;

      return session;
}

static struct pppol2tp_tunnel *next_tunnel(struct pppol2tp_tunnel *curr)
{
      struct pppol2tp_tunnel *tunnel = NULL;

      read_lock(&pppol2tp_tunnel_list_lock);
      if (list_is_last(&curr->list, &pppol2tp_tunnel_list)) {
            goto out;
      }
      tunnel = list_entry(curr->list.next, struct pppol2tp_tunnel, list);
out:
      read_unlock(&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;
      loff_t pos = *offs;

      if (!pos)
            goto out;

      BUG_ON(m->private == NULL);
      pd = m->private;

      if (pd->tunnel == NULL) {
            if (!list_empty(&pppol2tp_tunnel_list))
                  pd->tunnel = list_entry(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(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,
               tunnel->stats.tx_packets, tunnel->stats.tx_bytes,
               tunnel->stats.tx_errors,
               tunnel->stats.rx_packets, tunnel->stats.rx_bytes,
               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,
               session->stats.tx_packets,
               session->stats.tx_bytes,
               session->stats.tx_errors,
               session->stats.rx_packets,
               session->stats.rx_bytes,
               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 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)
{
      struct seq_file *m;
      struct pppol2tp_seq_data *pd;
      int ret = 0;

      ret = seq_open(file, &pppol2tp_seq_ops);
      if (ret < 0)
            goto out;

      m = file->private_data;

      /* Allocate and fill our proc_data for access later */
      ret = -ENOMEM;
      m->private = kzalloc(sizeof(struct pppol2tp_seq_data), GFP_KERNEL);
      if (m->private == NULL)
            goto out;

      pd = m->private;
      ret = 0;

out:
      return ret;
}

/* Called when /proc file access completes.
 */
static int pppol2tp_proc_release(struct inode *inode, struct file *file)
{
      struct seq_file *m = (struct seq_file *)file->private_data;

      kfree(m->private);
      m->private = NULL;

      return seq_release(inode, file);
}

static struct file_operations pppol2tp_proc_fops = {
      .owner            = THIS_MODULE,
      .open       = pppol2tp_proc_open,
      .read       = seq_read,
      .llseek           = seq_lseek,
      .release    = pppol2tp_proc_release,
};

static struct proc_dir_entry *pppol2tp_proc;

#endif /* CONFIG_PROC_FS */

/*****************************************************************************
 * Init and cleanup
 *****************************************************************************/

static 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 = 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;

#ifdef CONFIG_PROC_FS
      pppol2tp_proc = create_proc_entry("pppol2tp", 0, init_net.proc_net);
      if (!pppol2tp_proc) {
            err = -ENOMEM;
            goto out_unregister_pppox_proto;
      }
      pppol2tp_proc->proc_fops = &pppol2tp_proc_fops;
#endif /* CONFIG_PROC_FS */
      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);

#ifdef CONFIG_PROC_FS
      remove_proc_entry("pppol2tp", init_net.proc_net);
#endif
      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);

Generated by  Doxygen 1.6.0   Back to index