Logo Search packages:      
Sourcecode: linux-fsl-imx51 version File versions  Download package

ppp_generic.c

/*
 * Generic PPP layer for Linux.
 *
 * Copyright 1999-2002 Paul Mackerras.
 *
 *  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.
 *
 * The generic PPP layer handles the PPP network interfaces, the
 * /dev/ppp device, packet and VJ compression, and multilink.
 * It talks to PPP `channels' via the interface defined in
 * include/linux/ppp_channel.h.  Channels provide the basic means for
 * sending and receiving PPP frames on some kind of communications
 * channel.
 *
 * Part of the code in this driver was inspired by the old async-only
 * PPP driver, written by Michael Callahan and Al Longyear, and
 * subsequently hacked by Paul Mackerras.
 *
 * ==FILEVERSION 20041108==
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/idr.h>
#include <linux/netdevice.h>
#include <linux/poll.h>
#include <linux/ppp_defs.h>
#include <linux/filter.h>
#include <linux/if_ppp.h>
#include <linux/ppp_channel.h>
#include <linux/ppp-comp.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/if_arp.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/smp_lock.h>
#include <linux/spinlock.h>
#include <linux/rwsem.h>
#include <linux/stddef.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <net/slhc_vj.h>
#include <asm/atomic.h>

#include <linux/nsproxy.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>

#define PPP_VERSION     "2.4.2"

/*
 * Network protocols we support.
 */
#define NP_IP     0           /* Internet Protocol V4 */
#define NP_IPV6   1           /* Internet Protocol V6 */
#define NP_IPX    2           /* IPX protocol */
#define NP_AT     3           /* Appletalk protocol */
#define NP_MPLS_UC 4          /* MPLS unicast */
#define NP_MPLS_MC 5          /* MPLS multicast */
#define NUM_NP    6           /* Number of NPs. */

#define MPHDRLEN  6     /* multilink protocol header length */
#define MPHDRLEN_SSN    4     /* ditto with short sequence numbers */
#define MIN_FRAG_SIZE   64

/*
 * An instance of /dev/ppp can be associated with either a ppp
 * interface unit or a ppp channel.  In both cases, file->private_data
 * points to one of these.
 */
00078 struct ppp_file {
      enum {
            INTERFACE=1, CHANNEL
      }           kind;
      struct sk_buff_head xq;       /* pppd transmit queue */
      struct sk_buff_head rq;       /* receive queue for pppd */
      wait_queue_head_t rwait;      /* for poll on reading /dev/ppp */
      atomic_t    refcnt;           /* # refs (incl /dev/ppp attached) */
      int         hdrlen;           /* space to leave for headers */
      int         index;            /* interface unit / channel number */
      int         dead;       /* unit/channel has been shut down */
};

#define PF_TO_X(pf, X)        container_of(pf, X, file)

#define PF_TO_PPP(pf)         PF_TO_X(pf, struct ppp)
#define PF_TO_CHANNEL(pf)     PF_TO_X(pf, struct channel)

/*
 * Data structure describing one ppp unit.
 * A ppp unit corresponds to a ppp network interface device
 * and represents a multilink bundle.
 * It can have 0 or more ppp channels connected to it.
 */
00102 struct ppp {
      struct ppp_file   file;       /* stuff for read/write/poll 0 */
      struct file *owner;           /* file that owns this unit 48 */
      struct list_head channels;    /* list of attached channels 4c */
      int         n_channels; /* how many channels are attached 54 */
      spinlock_t  rlock;            /* lock for receive side 58 */
      spinlock_t  wlock;            /* lock for transmit side 5c */
      int         mru;        /* max receive unit 60 */
      unsigned int      flags;            /* control bits 64 */
      unsigned int      xstate;           /* transmit state bits 68 */
      unsigned int      rstate;           /* receive state bits 6c */
      int         debug;            /* debug flags 70 */
      struct slcompress *vj;        /* state for VJ header compression */
      enum NPmode npmode[NUM_NP];   /* what to do with each net proto 78 */
      struct sk_buff    *xmit_pending;    /* a packet ready to go out 88 */
      struct compressor *xcomp;     /* transmit packet compressor 8c */
      void        *xc_state;  /* its internal state 90 */
      struct compressor *rcomp;     /* receive decompressor 94 */
      void        *rc_state;  /* its internal state 98 */
      unsigned long     last_xmit;  /* jiffies when last pkt sent 9c */
      unsigned long     last_recv;  /* jiffies when last pkt rcvd a0 */
      struct net_device *dev;       /* network interface device a4 */
      int         closing;    /* is device closing down? a8 */
#ifdef CONFIG_PPP_MULTILINK
      int         nxchan;           /* next channel to send something on */
      u32         nxseq;            /* next sequence number to send */
      int         mrru;       /* MP: max reconst. receive unit */
      u32         nextseq;    /* MP: seq no of next packet */
      u32         minseq;           /* MP: min of most recent seqnos */
      struct sk_buff_head mrq;      /* MP: receive reconstruction queue */
#endif /* CONFIG_PPP_MULTILINK */
#ifdef CONFIG_PPP_FILTER
      struct sock_filter *pass_filter;    /* filter for packets to pass */
      struct sock_filter *active_filter;/* filter for pkts to reset idle */
      unsigned pass_len, active_len;
#endif /* CONFIG_PPP_FILTER */
      struct net  *ppp_net;   /* the net we belong to */
};

/*
 * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
 * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
 * SC_MUST_COMP
 * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
 * Bits in xstate: SC_COMP_RUN
 */
#define SC_FLAG_BITS    (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
                   |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
                   |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)

/*
 * Private data structure for each channel.
 * This includes the data structure used for multilink.
 */
struct channel {
      struct ppp_file   file;       /* stuff for read/write/poll */
      struct list_head list;        /* link in all/new_channels list */
      struct ppp_channel *chan;     /* public channel data structure */
      struct rw_semaphore chan_sem; /* protects `chan' during chan ioctl */
      spinlock_t  downl;            /* protects `chan', file.xq dequeue */
      struct ppp  *ppp;       /* ppp unit we're connected to */
      struct net  *chan_net;  /* the net channel belongs to */
      struct list_head clist;       /* link in list of channels per unit */
      rwlock_t    upl;        /* protects `ppp' */
#ifdef CONFIG_PPP_MULTILINK
      u8          avail;            /* flag used in multilink stuff */
      u8          had_frag;   /* >= 1 fragments have been sent */
      u32         lastseq;    /* MP: last sequence # received */
      int     speed;          /* speed of the corresponding ppp channel*/
#endif /* CONFIG_PPP_MULTILINK */
};

/*
 * SMP locking issues:
 * Both the ppp.rlock and ppp.wlock locks protect the ppp.channels
 * list and the ppp.n_channels field, you need to take both locks
 * before you modify them.
 * The lock ordering is: channel.upl -> ppp.wlock -> ppp.rlock ->
 * channel.downl.
 */

static atomic_t ppp_unit_count = ATOMIC_INIT(0);
static atomic_t channel_count = ATOMIC_INIT(0);

/* per-net private data for this module */
static int ppp_net_id;
00188 struct ppp_net {
      /* units to ppp mapping */
      struct idr units_idr;

      /*
       * all_ppp_mutex protects the units_idr mapping.
       * It also ensures that finding a ppp unit in the units_idr
       * map and updating its file.refcnt field is atomic.
       */
      struct mutex all_ppp_mutex;

      /* channels */
      struct list_head all_channels;
      struct list_head new_channels;
      int last_channel_index;

      /*
       * all_channels_lock protects all_channels and
       * last_channel_index, and the atomicity of find
       * a channel and updating its file.refcnt field.
       */
      spinlock_t all_channels_lock;
};

/* Get the PPP protocol number from a skb */
#define PPP_PROTO(skb)  (((skb)->data[0] << 8) + (skb)->data[1])

/* We limit the length of ppp->file.rq to this (arbitrary) value */
#define PPP_MAX_RQLEN   32

/*
 * Maximum number of multilink fragments queued up.
 * This has to be large enough to cope with the maximum latency of
 * the slowest channel relative to the others.  Strictly it should
 * depend on the number of channels and their characteristics.
 */
#define PPP_MP_MAX_QLEN 128

/* Multilink header bits. */
#define B   0x80        /* this fragment begins a packet */
#define E   0x40        /* this fragment ends a packet */

/* Compare multilink sequence numbers (assumed to be 32 bits wide) */
#define seq_before(a, b)      ((s32)((a) - (b)) < 0)
#define seq_after(a, b)       ((s32)((a) - (b)) > 0)

/* Prototypes. */
static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
                  struct file *file, unsigned int cmd, unsigned long arg);
static void ppp_xmit_process(struct ppp *ppp);
static void ppp_send_frame(struct ppp *ppp, struct sk_buff *skb);
static void ppp_push(struct ppp *ppp);
static void ppp_channel_push(struct channel *pch);
static void ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb,
                        struct channel *pch);
static void ppp_receive_error(struct ppp *ppp);
static void ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb);
static struct sk_buff *ppp_decompress_frame(struct ppp *ppp,
                                  struct sk_buff *skb);
#ifdef CONFIG_PPP_MULTILINK
static void ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb,
                        struct channel *pch);
static void ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb);
static struct sk_buff *ppp_mp_reconstruct(struct ppp *ppp);
static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb);
#endif /* CONFIG_PPP_MULTILINK */
static int ppp_set_compress(struct ppp *ppp, unsigned long arg);
static void ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound);
static void ppp_ccp_closed(struct ppp *ppp);
static struct compressor *find_compressor(int type);
static void ppp_get_stats(struct ppp *ppp, struct ppp_stats *st);
static struct ppp *ppp_create_interface(struct net *net, int unit, int *retp);
static void init_ppp_file(struct ppp_file *pf, int kind);
static void ppp_shutdown_interface(struct ppp *ppp);
static void ppp_destroy_interface(struct ppp *ppp);
static struct ppp *ppp_find_unit(struct ppp_net *pn, int unit);
static struct channel *ppp_find_channel(struct ppp_net *pn, int unit);
static int ppp_connect_channel(struct channel *pch, int unit);
static int ppp_disconnect_channel(struct channel *pch);
static void ppp_destroy_channel(struct channel *pch);
static int unit_get(struct idr *p, void *ptr);
static int unit_set(struct idr *p, void *ptr, int n);
static void unit_put(struct idr *p, int n);
static void *unit_find(struct idr *p, int n);

static struct class *ppp_class;

/* per net-namespace data */
static inline struct ppp_net *ppp_pernet(struct net *net)
{
      BUG_ON(!net);

      return net_generic(net, ppp_net_id);
}

/* Translates a PPP protocol number to a NP index (NP == network protocol) */
static inline int proto_to_npindex(int proto)
{
      switch (proto) {
      case PPP_IP:
            return NP_IP;
      case PPP_IPV6:
            return NP_IPV6;
      case PPP_IPX:
            return NP_IPX;
      case PPP_AT:
            return NP_AT;
      case PPP_MPLS_UC:
            return NP_MPLS_UC;
      case PPP_MPLS_MC:
            return NP_MPLS_MC;
      }
      return -EINVAL;
}

/* Translates an NP index into a PPP protocol number */
static const int npindex_to_proto[NUM_NP] = {
      PPP_IP,
      PPP_IPV6,
      PPP_IPX,
      PPP_AT,
      PPP_MPLS_UC,
      PPP_MPLS_MC,
};

/* Translates an ethertype into an NP index */
static inline int ethertype_to_npindex(int ethertype)
{
      switch (ethertype) {
      case ETH_P_IP:
            return NP_IP;
      case ETH_P_IPV6:
            return NP_IPV6;
      case ETH_P_IPX:
            return NP_IPX;
      case ETH_P_PPPTALK:
      case ETH_P_ATALK:
            return NP_AT;
      case ETH_P_MPLS_UC:
            return NP_MPLS_UC;
      case ETH_P_MPLS_MC:
            return NP_MPLS_MC;
      }
      return -1;
}

/* Translates an NP index into an ethertype */
static const int npindex_to_ethertype[NUM_NP] = {
      ETH_P_IP,
      ETH_P_IPV6,
      ETH_P_IPX,
      ETH_P_PPPTALK,
      ETH_P_MPLS_UC,
      ETH_P_MPLS_MC,
};

/*
 * Locking shorthand.
 */
#define ppp_xmit_lock(ppp)    spin_lock_bh(&(ppp)->wlock)
#define ppp_xmit_unlock(ppp)  spin_unlock_bh(&(ppp)->wlock)
#define ppp_recv_lock(ppp)    spin_lock_bh(&(ppp)->rlock)
#define ppp_recv_unlock(ppp)  spin_unlock_bh(&(ppp)->rlock)
#define ppp_lock(ppp)         do { ppp_xmit_lock(ppp); \
                             ppp_recv_lock(ppp); } while (0)
#define ppp_unlock(ppp)       do { ppp_recv_unlock(ppp); \
                             ppp_xmit_unlock(ppp); } while (0)

/*
 * /dev/ppp device routines.
 * The /dev/ppp device is used by pppd to control the ppp unit.
 * It supports the read, write, ioctl and poll functions.
 * Open instances of /dev/ppp can be in one of three states:
 * unattached, attached to a ppp unit, or attached to a ppp channel.
 */
static int ppp_open(struct inode *inode, struct file *file)
{
      cycle_kernel_lock();
      /*
       * This could (should?) be enforced by the permissions on /dev/ppp.
       */
      if (!capable(CAP_NET_ADMIN))
            return -EPERM;
      return 0;
}

static int ppp_release(struct inode *unused, struct file *file)
{
      struct ppp_file *pf = file->private_data;
      struct ppp *ppp;

      if (pf) {
            file->private_data = NULL;
            if (pf->kind == INTERFACE) {
                  ppp = PF_TO_PPP(pf);
                  if (file == ppp->owner)
                        ppp_shutdown_interface(ppp);
            }
            if (atomic_dec_and_test(&pf->refcnt)) {
                  switch (pf->kind) {
                  case INTERFACE:
                        ppp_destroy_interface(PF_TO_PPP(pf));
                        break;
                  case CHANNEL:
                        ppp_destroy_channel(PF_TO_CHANNEL(pf));
                        break;
                  }
            }
      }
      return 0;
}

static ssize_t ppp_read(struct file *file, char __user *buf,
                  size_t count, loff_t *ppos)
{
      struct ppp_file *pf = file->private_data;
      DECLARE_WAITQUEUE(wait, current);
      ssize_t ret;
      struct sk_buff *skb = NULL;

      ret = count;

      if (!pf)
            return -ENXIO;
      add_wait_queue(&pf->rwait, &wait);
      for (;;) {
            set_current_state(TASK_INTERRUPTIBLE);
            skb = skb_dequeue(&pf->rq);
            if (skb)
                  break;
            ret = 0;
            if (pf->dead)
                  break;
            if (pf->kind == INTERFACE) {
                  /*
                   * Return 0 (EOF) on an interface that has no
                   * channels connected, unless it is looping
                   * network traffic (demand mode).
                   */
                  struct ppp *ppp = PF_TO_PPP(pf);
                  if (ppp->n_channels == 0
                      && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
                        break;
            }
            ret = -EAGAIN;
            if (file->f_flags & O_NONBLOCK)
                  break;
            ret = -ERESTARTSYS;
            if (signal_pending(current))
                  break;
            schedule();
      }
      set_current_state(TASK_RUNNING);
      remove_wait_queue(&pf->rwait, &wait);

      if (!skb)
            goto out;

      ret = -EOVERFLOW;
      if (skb->len > count)
            goto outf;
      ret = -EFAULT;
      if (copy_to_user(buf, skb->data, skb->len))
            goto outf;
      ret = skb->len;

 outf:
      kfree_skb(skb);
 out:
      return ret;
}

static ssize_t ppp_write(struct file *file, const char __user *buf,
                   size_t count, loff_t *ppos)
{
      struct ppp_file *pf = file->private_data;
      struct sk_buff *skb;
      ssize_t ret;

      if (!pf)
            return -ENXIO;
      ret = -ENOMEM;
      skb = alloc_skb(count + pf->hdrlen, GFP_KERNEL);
      if (!skb)
            goto out;
      skb_reserve(skb, pf->hdrlen);
      ret = -EFAULT;
      if (copy_from_user(skb_put(skb, count), buf, count)) {
            kfree_skb(skb);
            goto out;
      }

      skb_queue_tail(&pf->xq, skb);

      switch (pf->kind) {
      case INTERFACE:
            ppp_xmit_process(PF_TO_PPP(pf));
            break;
      case CHANNEL:
            ppp_channel_push(PF_TO_CHANNEL(pf));
            break;
      }

      ret = count;

 out:
      return ret;
}

/* No kernel lock - fine */
static unsigned int ppp_poll(struct file *file, poll_table *wait)
{
      struct ppp_file *pf = file->private_data;
      unsigned int mask;

      if (!pf)
            return 0;
      poll_wait(file, &pf->rwait, wait);
      mask = POLLOUT | POLLWRNORM;
      if (skb_peek(&pf->rq))
            mask |= POLLIN | POLLRDNORM;
      if (pf->dead)
            mask |= POLLHUP;
      else if (pf->kind == INTERFACE) {
            /* see comment in ppp_read */
            struct ppp *ppp = PF_TO_PPP(pf);
            if (ppp->n_channels == 0
                && (ppp->flags & SC_LOOP_TRAFFIC) == 0)
                  mask |= POLLIN | POLLRDNORM;
      }

      return mask;
}

#ifdef CONFIG_PPP_FILTER
static int get_filter(void __user *arg, struct sock_filter **p)
{
      struct sock_fprog uprog;
      struct sock_filter *code = NULL;
      int len, err;

      if (copy_from_user(&uprog, arg, sizeof(uprog)))
            return -EFAULT;

      if (!uprog.len) {
            *p = NULL;
            return 0;
      }

      len = uprog.len * sizeof(struct sock_filter);
      code = kmalloc(len, GFP_KERNEL);
      if (code == NULL)
            return -ENOMEM;

      if (copy_from_user(code, uprog.filter, len)) {
            kfree(code);
            return -EFAULT;
      }

      err = sk_chk_filter(code, uprog.len);
      if (err) {
            kfree(code);
            return err;
      }

      *p = code;
      return uprog.len;
}
#endif /* CONFIG_PPP_FILTER */

static long ppp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
      struct ppp_file *pf = file->private_data;
      struct ppp *ppp;
      int err = -EFAULT, val, val2, i;
      struct ppp_idle idle;
      struct npioctl npi;
      int unit, cflags;
      struct slcompress *vj;
      void __user *argp = (void __user *)arg;
      int __user *p = argp;

      if (!pf)
            return ppp_unattached_ioctl(current->nsproxy->net_ns,
                              pf, file, cmd, arg);

      if (cmd == PPPIOCDETACH) {
            /*
             * We have to be careful here... if the file descriptor
             * has been dup'd, we could have another process in the
             * middle of a poll using the same file *, so we had
             * better not free the interface data structures -
             * instead we fail the ioctl.  Even in this case, we
             * shut down the interface if we are the owner of it.
             * Actually, we should get rid of PPPIOCDETACH, userland
             * (i.e. pppd) could achieve the same effect by closing
             * this fd and reopening /dev/ppp.
             */
            err = -EINVAL;
            lock_kernel();
            if (pf->kind == INTERFACE) {
                  ppp = PF_TO_PPP(pf);
                  if (file == ppp->owner)
                        ppp_shutdown_interface(ppp);
            }
            if (atomic_long_read(&file->f_count) <= 2) {
                  ppp_release(NULL, file);
                  err = 0;
            } else
                  printk(KERN_DEBUG "PPPIOCDETACH file->f_count=%ld\n",
                         atomic_long_read(&file->f_count));
            unlock_kernel();
            return err;
      }

      if (pf->kind == CHANNEL) {
            struct channel *pch;
            struct ppp_channel *chan;

            lock_kernel();
            pch = PF_TO_CHANNEL(pf);

            switch (cmd) {
            case PPPIOCCONNECT:
                  if (get_user(unit, p))
                        break;
                  err = ppp_connect_channel(pch, unit);
                  break;

            case PPPIOCDISCONN:
                  err = ppp_disconnect_channel(pch);
                  break;

            default:
                  down_read(&pch->chan_sem);
                  chan = pch->chan;
                  err = -ENOTTY;
                  if (chan && chan->ops->ioctl)
                        err = chan->ops->ioctl(chan, cmd, arg);
                  up_read(&pch->chan_sem);
            }
            unlock_kernel();
            return err;
      }

      if (pf->kind != INTERFACE) {
            /* can't happen */
            printk(KERN_ERR "PPP: not interface or channel??\n");
            return -EINVAL;
      }

      lock_kernel();
      ppp = PF_TO_PPP(pf);
      switch (cmd) {
      case PPPIOCSMRU:
            if (get_user(val, p))
                  break;
            ppp->mru = val;
            err = 0;
            break;

      case PPPIOCSFLAGS:
            if (get_user(val, p))
                  break;
            ppp_lock(ppp);
            cflags = ppp->flags & ~val;
            ppp->flags = val & SC_FLAG_BITS;
            ppp_unlock(ppp);
            if (cflags & SC_CCP_OPEN)
                  ppp_ccp_closed(ppp);
            err = 0;
            break;

      case PPPIOCGFLAGS:
            val = ppp->flags | ppp->xstate | ppp->rstate;
            if (put_user(val, p))
                  break;
            err = 0;
            break;

      case PPPIOCSCOMPRESS:
            err = ppp_set_compress(ppp, arg);
            break;

      case PPPIOCGUNIT:
            if (put_user(ppp->file.index, p))
                  break;
            err = 0;
            break;

      case PPPIOCSDEBUG:
            if (get_user(val, p))
                  break;
            ppp->debug = val;
            err = 0;
            break;

      case PPPIOCGDEBUG:
            if (put_user(ppp->debug, p))
                  break;
            err = 0;
            break;

      case PPPIOCGIDLE:
            idle.xmit_idle = (jiffies - ppp->last_xmit) / HZ;
            idle.recv_idle = (jiffies - ppp->last_recv) / HZ;
            if (copy_to_user(argp, &idle, sizeof(idle)))
                  break;
            err = 0;
            break;

      case PPPIOCSMAXCID:
            if (get_user(val, p))
                  break;
            val2 = 15;
            if ((val >> 16) != 0) {
                  val2 = val >> 16;
                  val &= 0xffff;
            }
            vj = slhc_init(val2+1, val+1);
            if (!vj) {
                  printk(KERN_ERR "PPP: no memory (VJ compressor)\n");
                  err = -ENOMEM;
                  break;
            }
            ppp_lock(ppp);
            if (ppp->vj)
                  slhc_free(ppp->vj);
            ppp->vj = vj;
            ppp_unlock(ppp);
            err = 0;
            break;

      case PPPIOCGNPMODE:
      case PPPIOCSNPMODE:
            if (copy_from_user(&npi, argp, sizeof(npi)))
                  break;
            err = proto_to_npindex(npi.protocol);
            if (err < 0)
                  break;
            i = err;
            if (cmd == PPPIOCGNPMODE) {
                  err = -EFAULT;
                  npi.mode = ppp->npmode[i];
                  if (copy_to_user(argp, &npi, sizeof(npi)))
                        break;
            } else {
                  ppp->npmode[i] = npi.mode;
                  /* we may be able to transmit more packets now (??) */
                  netif_wake_queue(ppp->dev);
            }
            err = 0;
            break;

#ifdef CONFIG_PPP_FILTER
      case PPPIOCSPASS:
      {
            struct sock_filter *code;
            err = get_filter(argp, &code);
            if (err >= 0) {
                  ppp_lock(ppp);
                  kfree(ppp->pass_filter);
                  ppp->pass_filter = code;
                  ppp->pass_len = err;
                  ppp_unlock(ppp);
                  err = 0;
            }
            break;
      }
      case PPPIOCSACTIVE:
      {
            struct sock_filter *code;
            err = get_filter(argp, &code);
            if (err >= 0) {
                  ppp_lock(ppp);
                  kfree(ppp->active_filter);
                  ppp->active_filter = code;
                  ppp->active_len = err;
                  ppp_unlock(ppp);
                  err = 0;
            }
            break;
      }
#endif /* CONFIG_PPP_FILTER */

#ifdef CONFIG_PPP_MULTILINK
      case PPPIOCSMRRU:
            if (get_user(val, p))
                  break;
            ppp_recv_lock(ppp);
            ppp->mrru = val;
            ppp_recv_unlock(ppp);
            err = 0;
            break;
#endif /* CONFIG_PPP_MULTILINK */

      default:
            err = -ENOTTY;
      }
      unlock_kernel();
      return err;
}

static int ppp_unattached_ioctl(struct net *net, struct ppp_file *pf,
                  struct file *file, unsigned int cmd, unsigned long arg)
{
      int unit, err = -EFAULT;
      struct ppp *ppp;
      struct channel *chan;
      struct ppp_net *pn;
      int __user *p = (int __user *)arg;

      lock_kernel();
      switch (cmd) {
      case PPPIOCNEWUNIT:
            /* Create a new ppp unit */
            if (get_user(unit, p))
                  break;
            ppp = ppp_create_interface(net, unit, &err);
            if (!ppp)
                  break;
            file->private_data = &ppp->file;
            ppp->owner = file;
            err = -EFAULT;
            if (put_user(ppp->file.index, p))
                  break;
            err = 0;
            break;

      case PPPIOCATTACH:
            /* Attach to an existing ppp unit */
            if (get_user(unit, p))
                  break;
            err = -ENXIO;
            pn = ppp_pernet(net);
            mutex_lock(&pn->all_ppp_mutex);
            ppp = ppp_find_unit(pn, unit);
            if (ppp) {
                  atomic_inc(&ppp->file.refcnt);
                  file->private_data = &ppp->file;
                  err = 0;
            }
            mutex_unlock(&pn->all_ppp_mutex);
            break;

      case PPPIOCATTCHAN:
            if (get_user(unit, p))
                  break;
            err = -ENXIO;
            pn = ppp_pernet(net);
            spin_lock_bh(&pn->all_channels_lock);
            chan = ppp_find_channel(pn, unit);
            if (chan) {
                  atomic_inc(&chan->file.refcnt);
                  file->private_data = &chan->file;
                  err = 0;
            }
            spin_unlock_bh(&pn->all_channels_lock);
            break;

      default:
            err = -ENOTTY;
      }
      unlock_kernel();
      return err;
}

static const struct file_operations ppp_device_fops = {
      .owner            = THIS_MODULE,
      .read       = ppp_read,
      .write            = ppp_write,
      .poll       = ppp_poll,
      .unlocked_ioctl   = ppp_ioctl,
      .open       = ppp_open,
      .release    = ppp_release
};

static __net_init int ppp_init_net(struct net *net)
{
      struct ppp_net *pn;
      int err;

      pn = kzalloc(sizeof(*pn), GFP_KERNEL);
      if (!pn)
            return -ENOMEM;

      idr_init(&pn->units_idr);
      mutex_init(&pn->all_ppp_mutex);

      INIT_LIST_HEAD(&pn->all_channels);
      INIT_LIST_HEAD(&pn->new_channels);

      spin_lock_init(&pn->all_channels_lock);

      err = net_assign_generic(net, ppp_net_id, pn);
      if (err) {
            kfree(pn);
            return err;
      }

      return 0;
}

static __net_exit void ppp_exit_net(struct net *net)
{
      struct ppp_net *pn;

      pn = net_generic(net, ppp_net_id);
      idr_destroy(&pn->units_idr);
      /*
       * if someone has cached our net then
       * further net_generic call will return NULL
       */
      net_assign_generic(net, ppp_net_id, NULL);
      kfree(pn);
}

static struct pernet_operations ppp_net_ops = {
      .init = ppp_init_net,
      .exit = ppp_exit_net,
};

#define PPP_MAJOR 108

/* Called at boot time if ppp is compiled into the kernel,
   or at module load time (from init_module) if compiled as a module. */
static int __init ppp_init(void)
{
      int err;

      printk(KERN_INFO "PPP generic driver version " PPP_VERSION "\n");

      err = register_pernet_gen_device(&ppp_net_id, &ppp_net_ops);
      if (err) {
            printk(KERN_ERR "failed to register PPP pernet device (%d)\n", err);
            goto out;
      }

      err = register_chrdev(PPP_MAJOR, "ppp", &ppp_device_fops);
      if (err) {
            printk(KERN_ERR "failed to register PPP device (%d)\n", err);
            goto out_net;
      }

      ppp_class = class_create(THIS_MODULE, "ppp");
      if (IS_ERR(ppp_class)) {
            err = PTR_ERR(ppp_class);
            goto out_chrdev;
      }

      /* not a big deal if we fail here :-) */
      device_create(ppp_class, NULL, MKDEV(PPP_MAJOR, 0), NULL, "ppp");

      return 0;

out_chrdev:
      unregister_chrdev(PPP_MAJOR, "ppp");
out_net:
      unregister_pernet_gen_device(ppp_net_id, &ppp_net_ops);
out:
      return err;
}

/*
 * Network interface unit routines.
 */
static int
ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
      struct ppp *ppp = netdev_priv(dev);
      int npi, proto;
      unsigned char *pp;

      npi = ethertype_to_npindex(ntohs(skb->protocol));
      if (npi < 0)
            goto outf;

      /* Drop, accept or reject the packet */
      switch (ppp->npmode[npi]) {
      case NPMODE_PASS:
            break;
      case NPMODE_QUEUE:
            /* it would be nice to have a way to tell the network
               system to queue this one up for later. */
            goto outf;
      case NPMODE_DROP:
      case NPMODE_ERROR:
            goto outf;
      }

      /* Put the 2-byte PPP protocol number on the front,
         making sure there is room for the address and control fields. */
      if (skb_cow_head(skb, PPP_HDRLEN))
            goto outf;

      pp = skb_push(skb, 2);
      proto = npindex_to_proto[npi];
      pp[0] = proto >> 8;
      pp[1] = proto;

      netif_stop_queue(dev);
      skb_queue_tail(&ppp->file.xq, skb);
      ppp_xmit_process(ppp);
      return 0;

 outf:
      kfree_skb(skb);
      ++dev->stats.tx_dropped;
      return 0;
}

static int
ppp_net_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
      struct ppp *ppp = netdev_priv(dev);
      int err = -EFAULT;
      void __user *addr = (void __user *) ifr->ifr_ifru.ifru_data;
      struct ppp_stats stats;
      struct ppp_comp_stats cstats;
      char *vers;

      switch (cmd) {
      case SIOCGPPPSTATS:
            ppp_get_stats(ppp, &stats);
            if (copy_to_user(addr, &stats, sizeof(stats)))
                  break;
            err = 0;
            break;

      case SIOCGPPPCSTATS:
            memset(&cstats, 0, sizeof(cstats));
            if (ppp->xc_state)
                  ppp->xcomp->comp_stat(ppp->xc_state, &cstats.c);
            if (ppp->rc_state)
                  ppp->rcomp->decomp_stat(ppp->rc_state, &cstats.d);
            if (copy_to_user(addr, &cstats, sizeof(cstats)))
                  break;
            err = 0;
            break;

      case SIOCGPPPVER:
            vers = PPP_VERSION;
            if (copy_to_user(addr, vers, strlen(vers) + 1))
                  break;
            err = 0;
            break;

      default:
            err = -EINVAL;
      }

      return err;
}

static const struct net_device_ops ppp_netdev_ops = {
      .ndo_start_xmit = ppp_start_xmit,
      .ndo_do_ioctl   = ppp_net_ioctl,
};

static void ppp_setup(struct net_device *dev)
{
      dev->netdev_ops = &ppp_netdev_ops;
      dev->hard_header_len = PPP_HDRLEN;
      dev->mtu = PPP_MTU;
      dev->addr_len = 0;
      dev->tx_queue_len = 3;
      dev->type = ARPHRD_PPP;
      dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
      dev->features |= NETIF_F_NETNS_LOCAL;
      dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
}

/*
 * Transmit-side routines.
 */

/*
 * Called to do any work queued up on the transmit side
 * that can now be done.
 */
static void
ppp_xmit_process(struct ppp *ppp)
{
      struct sk_buff *skb;

      ppp_xmit_lock(ppp);
      if (!ppp->closing) {
            ppp_push(ppp);
            while (!ppp->xmit_pending
                   && (skb = skb_dequeue(&ppp->file.xq)))
                  ppp_send_frame(ppp, skb);
            /* If there's no work left to do, tell the core net
               code that we can accept some more. */
            if (!ppp->xmit_pending && !skb_peek(&ppp->file.xq))
                  netif_wake_queue(ppp->dev);
      }
      ppp_xmit_unlock(ppp);
}

static inline struct sk_buff *
pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
{
      struct sk_buff *new_skb;
      int len;
      int new_skb_size = ppp->dev->mtu +
            ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
      int compressor_skb_size = ppp->dev->mtu +
            ppp->xcomp->comp_extra + PPP_HDRLEN;
      new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
      if (!new_skb) {
            if (net_ratelimit())
                  printk(KERN_ERR "PPP: no memory (comp pkt)\n");
            return NULL;
      }
      if (ppp->dev->hard_header_len > PPP_HDRLEN)
            skb_reserve(new_skb,
                      ppp->dev->hard_header_len - PPP_HDRLEN);

      /* compressor still expects A/C bytes in hdr */
      len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
                           new_skb->data, skb->len + 2,
                           compressor_skb_size);
      if (len > 0 && (ppp->flags & SC_CCP_UP)) {
            kfree_skb(skb);
            skb = new_skb;
            skb_put(skb, len);
            skb_pull(skb, 2); /* pull off A/C bytes */
      } else if (len == 0) {
            /* didn't compress, or CCP not up yet */
            kfree_skb(new_skb);
            new_skb = skb;
      } else {
            /*
             * (len < 0)
             * MPPE requires that we do not send unencrypted
             * frames.  The compressor will return -1 if we
             * should drop the frame.  We cannot simply test
             * the compress_proto because MPPE and MPPC share
             * the same number.
             */
            if (net_ratelimit())
                  printk(KERN_ERR "ppp: compressor dropped pkt\n");
            kfree_skb(skb);
            kfree_skb(new_skb);
            new_skb = NULL;
      }
      return new_skb;
}

/*
 * Compress and send a frame.
 * The caller should have locked the xmit path,
 * and xmit_pending should be 0.
 */
static void
ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
{
      int proto = PPP_PROTO(skb);
      struct sk_buff *new_skb;
      int len;
      unsigned char *cp;

      if (proto < 0x8000) {
#ifdef CONFIG_PPP_FILTER
            /* check if we should pass this packet */
            /* the filter instructions are constructed assuming
               a four-byte PPP header on each packet */
            *skb_push(skb, 2) = 1;
            if (ppp->pass_filter
                && sk_run_filter(skb, ppp->pass_filter,
                             ppp->pass_len) == 0) {
                  if (ppp->debug & 1)
                        printk(KERN_DEBUG "PPP: outbound frame not passed\n");
                  kfree_skb(skb);
                  return;
            }
            /* if this packet passes the active filter, record the time */
            if (!(ppp->active_filter
                  && sk_run_filter(skb, ppp->active_filter,
                               ppp->active_len) == 0))
                  ppp->last_xmit = jiffies;
            skb_pull(skb, 2);
#else
            /* for data packets, record the time */
            ppp->last_xmit = jiffies;
#endif /* CONFIG_PPP_FILTER */
      }

      ++ppp->dev->stats.tx_packets;
      ppp->dev->stats.tx_bytes += skb->len - 2;

      switch (proto) {
      case PPP_IP:
            if (!ppp->vj || (ppp->flags & SC_COMP_TCP) == 0)
                  break;
            /* try to do VJ TCP header compression */
            new_skb = alloc_skb(skb->len + ppp->dev->hard_header_len - 2,
                            GFP_ATOMIC);
            if (!new_skb) {
                  printk(KERN_ERR "PPP: no memory (VJ comp pkt)\n");
                  goto drop;
            }
            skb_reserve(new_skb, ppp->dev->hard_header_len - 2);
            cp = skb->data + 2;
            len = slhc_compress(ppp->vj, cp, skb->len - 2,
                            new_skb->data + 2, &cp,
                            !(ppp->flags & SC_NO_TCP_CCID));
            if (cp == skb->data + 2) {
                  /* didn't compress */
                  kfree_skb(new_skb);
            } else {
                  if (cp[0] & SL_TYPE_COMPRESSED_TCP) {
                        proto = PPP_VJC_COMP;
                        cp[0] &= ~SL_TYPE_COMPRESSED_TCP;
                  } else {
                        proto = PPP_VJC_UNCOMP;
                        cp[0] = skb->data[2];
                  }
                  kfree_skb(skb);
                  skb = new_skb;
                  cp = skb_put(skb, len + 2);
                  cp[0] = 0;
                  cp[1] = proto;
            }
            break;

      case PPP_CCP:
            /* peek at outbound CCP frames */
            ppp_ccp_peek(ppp, skb, 0);
            break;
      }

      /* try to do packet compression */
      if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state
          && proto != PPP_LCP && proto != PPP_CCP) {
            if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
                  if (net_ratelimit())
                        printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
                  goto drop;
            }
            skb = pad_compress_skb(ppp, skb);
            if (!skb)
                  goto drop;
      }

      /*
       * If we are waiting for traffic (demand dialling),
       * queue it up for pppd to receive.
       */
      if (ppp->flags & SC_LOOP_TRAFFIC) {
            if (ppp->file.rq.qlen > PPP_MAX_RQLEN)
                  goto drop;
            skb_queue_tail(&ppp->file.rq, skb);
            wake_up_interruptible(&ppp->file.rwait);
            return;
      }

      ppp->xmit_pending = skb;
      ppp_push(ppp);
      return;

 drop:
      kfree_skb(skb);
      ++ppp->dev->stats.tx_errors;
}

/*
 * Try to send the frame in xmit_pending.
 * The caller should have the xmit path locked.
 */
static void
ppp_push(struct ppp *ppp)
{
      struct list_head *list;
      struct channel *pch;
      struct sk_buff *skb = ppp->xmit_pending;

      if (!skb)
            return;

      list = &ppp->channels;
      if (list_empty(list)) {
            /* nowhere to send the packet, just drop it */
            ppp->xmit_pending = NULL;
            kfree_skb(skb);
            return;
      }

      if ((ppp->flags & SC_MULTILINK) == 0) {
            /* not doing multilink: send it down the first channel */
            list = list->next;
            pch = list_entry(list, struct channel, clist);

            spin_lock_bh(&pch->downl);
            if (pch->chan) {
                  if (pch->chan->ops->start_xmit(pch->chan, skb))
                        ppp->xmit_pending = NULL;
            } else {
                  /* channel got unregistered */
                  kfree_skb(skb);
                  ppp->xmit_pending = NULL;
            }
            spin_unlock_bh(&pch->downl);
            return;
      }

#ifdef CONFIG_PPP_MULTILINK
      /* Multilink: fragment the packet over as many links
         as can take the packet at the moment. */
      if (!ppp_mp_explode(ppp, skb))
            return;
#endif /* CONFIG_PPP_MULTILINK */

      ppp->xmit_pending = NULL;
      kfree_skb(skb);
}

#ifdef CONFIG_PPP_MULTILINK
/*
 * Divide a packet to be transmitted into fragments and
 * send them out the individual links.
 */
static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
{
      int   len, totlen;
      int   i, bits, hdrlen, mtu;
      int   flen;
      int   navail,     nfree, nzero;
      int   nbigger;
      int   totspeed;
      int   totfree;
      unsigned char *p, *q;
      struct list_head *list;
      struct channel *pch;
      struct sk_buff *frag;
      struct ppp_channel *chan;

      totspeed = 0; /*total bitrate of the bundle*/
      nfree =     0;    /* # channels which     have no     packet already queued */
      navail = 0; /* total # of usable channels (not deregistered) */
      nzero =     0; /* number of   channels with zero speed associated*/
      totfree     = 0; /*total # of channels available and
                          *having no queued packets before
                          *starting the fragmentation*/

      hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
      i =   0;
      list_for_each_entry(pch, &ppp->channels, clist) {
            navail += pch->avail = (pch->chan != NULL);
            pch->speed = pch->chan->speed;
            if (pch->avail)   {
                  if (skb_queue_empty(&pch->file.xq) ||
                        !pch->had_frag)   {
                              if (pch->speed == 0)
                                    nzero++;
                              else
                                    totspeed += pch->speed;

                              pch->avail = 2;
                              ++nfree;
                              ++totfree;
                        }
                  if (!pch->had_frag && i < ppp->nxchan)
                        ppp->nxchan = i;
            }
            ++i;
      }
      /*
       * Don't start sending this   packet unless at least half   of
       * the channels   are   free.  This gives much better TCP
       * performance if we have a   lot   of channels.
       */
      if (nfree == 0 || nfree < navail / 2)
            return 0; /* can't take now, leave it in xmit_pending */

      /* Do protocol field compression (XXX this should be optional) */
      p =   skb->data;
      len   = skb->len;
      if (*p == 0) {
            ++p;
            --len;
      }

      totlen = len;
      nbigger     = len %     nfree;

      /* skip     to the channel after the one we     last used
         and start at   that one */
      list = &ppp->channels;
      for   (i = 0;     i <   ppp->nxchan; ++i) {
            list = list->next;
            if (list == &ppp->channels)   {
                  i =   0;
                  break;
            }
      }

      /* create a fragment for each channel */
      bits = B;
      while (len  > 0) {
            list = list->next;
            if (list == &ppp->channels)   {
                  i =   0;
                  continue;
            }
            pch   = list_entry(list, struct channel, clist);
            ++i;
            if (!pch->avail)
                  continue;

            /*
             * Skip     this channel if   it has a fragment pending already and
             * we haven't given     a fragment to all of the free channels.
             */
            if (pch->avail == 1) {
                  if (nfree > 0)
                        continue;
            } else {
                  pch->avail = 1;
            }

            /* check the channel's mtu and whether it is still attached. */
            spin_lock_bh(&pch->downl);
            if (pch->chan == NULL) {
                  /* can't use this channel, it's     being deregistered */
                  if (pch->speed == 0)
                        nzero--;
                  else
                        totspeed -= pch->speed;

                  spin_unlock_bh(&pch->downl);
                  pch->avail = 0;
                  totlen = len;
                  totfree--;
                  nfree--;
                  if (--navail ==   0)
                        break;
                  continue;
            }

            /*
            *if the channel speed is not set divide
            *the packet evenly among the free channels;
            *otherwise divide it according to the speed
            *of the channel we are going to transmit on
            */
            if (nfree > 0) {
                  if (pch->speed == 0) {
                        flen = totlen/nfree     ;
                        if (nbigger > 0) {
                              flen++;
                              nbigger--;
                        }
                  } else {
                        flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) /
                              ((totspeed*totfree)/pch->speed)) - hdrlen;
                        if (nbigger > 0) {
                              flen += ((totfree - nzero)*pch->speed)/totspeed;
                              nbigger -= ((totfree - nzero)*pch->speed)/
                                          totspeed;
                        }
                  }
                  nfree--;
            }

            /*
             *check     if we are on the last channel or
             *we exceded the lenght of the data to
             *fragment
             */
            if ((nfree <= 0) || (flen > len))
                  flen = len;
            /*
             *it is not worth to tx on slow channels:
             *in that case from the resulting flen according to the
             *above formula will be equal or less than zero.
             *Skip the channel in this case
             */
            if (flen <= 0) {
                  pch->avail = 2;
                  spin_unlock_bh(&pch->downl);
                  continue;
            }

            mtu   = pch->chan->mtu - hdrlen;
            if (mtu     < 4)
                  mtu   = 4;
            if (flen > mtu)
                  flen = mtu;
            if (flen == len)
                  bits |=     E;
            frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
            if (!frag)
                  goto noskb;
            q =   skb_put(frag, flen + hdrlen);

            /* make     the   MP header */
            q[0] = PPP_MP >> 8;
            q[1] = PPP_MP;
            if (ppp->flags & SC_MP_XSHORTSEQ) {
                  q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
                  q[3] = ppp->nxseq;
            } else {
                  q[2] = bits;
                  q[3] = ppp->nxseq >> 16;
                  q[4] = ppp->nxseq >> 8;
                  q[5] = ppp->nxseq;
            }

            memcpy(q + hdrlen, p, flen);

            /* try to send it down the channel */
            chan = pch->chan;
            if (!skb_queue_empty(&pch->file.xq) ||
                  !chan->ops->start_xmit(chan, frag))
                  skb_queue_tail(&pch->file.xq, frag);
            pch->had_frag =   1;
            p += flen;
            len   -= flen;
            ++ppp->nxseq;
            bits = 0;
            spin_unlock_bh(&pch->downl);
      }
      ppp->nxchan = i;

      return 1;

 noskb:
      spin_unlock_bh(&pch->downl);
      if (ppp->debug & 1)
            printk(KERN_ERR   "PPP: no memory   (fragment)\n");
      ++ppp->dev->stats.tx_errors;
      ++ppp->nxseq;
      return 1;   /* abandon the frame */
}
#endif /* CONFIG_PPP_MULTILINK */

/*
 * Try to send data out on a channel.
 */
static void
ppp_channel_push(struct channel *pch)
{
      struct sk_buff *skb;
      struct ppp *ppp;

      spin_lock_bh(&pch->downl);
      if (pch->chan) {
            while (!skb_queue_empty(&pch->file.xq)) {
                  skb = skb_dequeue(&pch->file.xq);
                  if (!pch->chan->ops->start_xmit(pch->chan, skb)) {
                        /* put the packet back and try again later */
                        skb_queue_head(&pch->file.xq, skb);
                        break;
                  }
            }
      } else {
            /* channel got deregistered */
            skb_queue_purge(&pch->file.xq);
      }
      spin_unlock_bh(&pch->downl);
      /* see if there is anything from the attached unit to be sent */
      if (skb_queue_empty(&pch->file.xq)) {
            read_lock_bh(&pch->upl);
            ppp = pch->ppp;
            if (ppp)
                  ppp_xmit_process(ppp);
            read_unlock_bh(&pch->upl);
      }
}

/*
 * Receive-side routines.
 */

/* misuse a few fields of the skb for MP reconstruction */
#define sequence  priority
#define BEbits          cb[0]

static inline void
ppp_do_recv(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
{
      ppp_recv_lock(ppp);
      if (!ppp->closing)
            ppp_receive_frame(ppp, skb, pch);
      else
            kfree_skb(skb);
      ppp_recv_unlock(ppp);
}

void
ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
{
      struct channel *pch = chan->ppp;
      int proto;

      if (!pch || skb->len == 0) {
            kfree_skb(skb);
            return;
      }

      proto = PPP_PROTO(skb);
      read_lock_bh(&pch->upl);
      if (!pch->ppp || proto >= 0xc000 || proto == PPP_CCPFRAG) {
            /* put it on the channel queue */
            skb_queue_tail(&pch->file.rq, skb);
            /* drop old frames if queue too long */
            while (pch->file.rq.qlen > PPP_MAX_RQLEN
                   && (skb = skb_dequeue(&pch->file.rq)))
                  kfree_skb(skb);
            wake_up_interruptible(&pch->file.rwait);
      } else {
            ppp_do_recv(pch->ppp, skb, pch);
      }
      read_unlock_bh(&pch->upl);
}

/* Put a 0-length skb in the receive queue as an error indication */
void
ppp_input_error(struct ppp_channel *chan, int code)
{
      struct channel *pch = chan->ppp;
      struct sk_buff *skb;

      if (!pch)
            return;

      read_lock_bh(&pch->upl);
      if (pch->ppp) {
            skb = alloc_skb(0, GFP_ATOMIC);
            if (skb) {
                  skb->len = 0;           /* probably unnecessary */
                  skb->cb[0] = code;
                  ppp_do_recv(pch->ppp, skb, pch);
            }
      }
      read_unlock_bh(&pch->upl);
}

/*
 * We come in here to process a received frame.
 * The receive side of the ppp unit is locked.
 */
static void
ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
{
      if (pskb_may_pull(skb, 2)) {
#ifdef CONFIG_PPP_MULTILINK
            /* XXX do channel-level decompression here */
            if (PPP_PROTO(skb) == PPP_MP)
                  ppp_receive_mp_frame(ppp, skb, pch);
            else
#endif /* CONFIG_PPP_MULTILINK */
                  ppp_receive_nonmp_frame(ppp, skb);
            return;
      }

      if (skb->len > 0)
            /* note: a 0-length skb is used as an error indication */
            ++ppp->dev->stats.rx_length_errors;

      kfree_skb(skb);
      ppp_receive_error(ppp);
}

static void
ppp_receive_error(struct ppp *ppp)
{
      ++ppp->dev->stats.rx_errors;
      if (ppp->vj)
            slhc_toss(ppp->vj);
}

static void
ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
{
      struct sk_buff *ns;
      int proto, len, npi;

      /*
       * Decompress the frame, if compressed.
       * Note that some decompressors need to see uncompressed frames
       * that come in as well as compressed frames.
       */
      if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)
          && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
            skb = ppp_decompress_frame(ppp, skb);

      if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
            goto err;

      proto = PPP_PROTO(skb);
      switch (proto) {
      case PPP_VJC_COMP:
            /* decompress VJ compressed packets */
            if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
                  goto err;

            if (skb_tailroom(skb) < 124 || skb_cloned(skb)) {
                  /* copy to a new sk_buff with more tailroom */
                  ns = dev_alloc_skb(skb->len + 128);
                  if (!ns) {
                        printk(KERN_ERR"PPP: no memory (VJ decomp)\n");
                        goto err;
                  }
                  skb_reserve(ns, 2);
                  skb_copy_bits(skb, 0, skb_put(ns, skb->len), skb->len);
                  kfree_skb(skb);
                  skb = ns;
            }
            else
                  skb->ip_summed = CHECKSUM_NONE;

            len = slhc_uncompress(ppp->vj, skb->data + 2, skb->len - 2);
            if (len <= 0) {
                  printk(KERN_DEBUG "PPP: VJ decompression error\n");
                  goto err;
            }
            len += 2;
            if (len > skb->len)
                  skb_put(skb, len - skb->len);
            else if (len < skb->len)
                  skb_trim(skb, len);
            proto = PPP_IP;
            break;

      case PPP_VJC_UNCOMP:
            if (!ppp->vj || (ppp->flags & SC_REJ_COMP_TCP))
                  goto err;

            /* Until we fix the decompressor need to make sure
             * data portion is linear.
             */
            if (!pskb_may_pull(skb, skb->len))
                  goto err;

            if (slhc_remember(ppp->vj, skb->data + 2, skb->len - 2) <= 0) {
                  printk(KERN_ERR "PPP: VJ uncompressed error\n");
                  goto err;
            }
            proto = PPP_IP;
            break;

      case PPP_CCP:
            ppp_ccp_peek(ppp, skb, 1);
            break;
      }

      ++ppp->dev->stats.rx_packets;
      ppp->dev->stats.rx_bytes += skb->len - 2;

      npi = proto_to_npindex(proto);
      if (npi < 0) {
            /* control or unknown frame - pass it to pppd */
            skb_queue_tail(&ppp->file.rq, skb);
            /* limit queue length by dropping old frames */
            while (ppp->file.rq.qlen > PPP_MAX_RQLEN
                   && (skb = skb_dequeue(&ppp->file.rq)))
                  kfree_skb(skb);
            /* wake up any process polling or blocking on read */
            wake_up_interruptible(&ppp->file.rwait);

      } else {
            /* network protocol frame - give it to the kernel */

#ifdef CONFIG_PPP_FILTER
            /* check if the packet passes the pass and active filters */
            /* the filter instructions are constructed assuming
               a four-byte PPP header on each packet */
            if (ppp->pass_filter || ppp->active_filter) {
                  if (skb_cloned(skb) &&
                      pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
                        goto err;

                  *skb_push(skb, 2) = 0;
                  if (ppp->pass_filter
                      && sk_run_filter(skb, ppp->pass_filter,
                                   ppp->pass_len) == 0) {
                        if (ppp->debug & 1)
                              printk(KERN_DEBUG "PPP: inbound frame "
                                     "not passed\n");
                        kfree_skb(skb);
                        return;
                  }
                  if (!(ppp->active_filter
                        && sk_run_filter(skb, ppp->active_filter,
                                     ppp->active_len) == 0))
                        ppp->last_recv = jiffies;
                  __skb_pull(skb, 2);
            } else
#endif /* CONFIG_PPP_FILTER */
                  ppp->last_recv = jiffies;

            if ((ppp->dev->flags & IFF_UP) == 0
                || ppp->npmode[npi] != NPMODE_PASS) {
                  kfree_skb(skb);
            } else {
                  /* chop off protocol */
                  skb_pull_rcsum(skb, 2);
                  skb->dev = ppp->dev;
                  skb->protocol = htons(npindex_to_ethertype[npi]);
                  skb_reset_mac_header(skb);
                  netif_rx(skb);
            }
      }
      return;

 err:
      kfree_skb(skb);
      ppp_receive_error(ppp);
}

static struct sk_buff *
ppp_decompress_frame(struct ppp *ppp, struct sk_buff *skb)
{
      int proto = PPP_PROTO(skb);
      struct sk_buff *ns;
      int len;

      /* Until we fix all the decompressor's need to make sure
       * data portion is linear.
       */
      if (!pskb_may_pull(skb, skb->len))
            goto err;

      if (proto == PPP_COMP) {
            int obuff_size;

            switch(ppp->rcomp->compress_proto) {
            case CI_MPPE:
                  obuff_size = ppp->mru + PPP_HDRLEN + 1;
                  break;
            default:
                  obuff_size = ppp->mru + PPP_HDRLEN;
                  break;
            }

            ns = dev_alloc_skb(obuff_size);
            if (!ns) {
                  printk(KERN_ERR "ppp_decompress_frame: no memory\n");
                  goto err;
            }
            /* the decompressor still expects the A/C bytes in the hdr */
            len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
                        skb->len + 2, ns->data, obuff_size);
            if (len < 0) {
                  /* Pass the compressed frame to pppd as an
                     error indication. */
                  if (len == DECOMP_FATALERROR)
                        ppp->rstate |= SC_DC_FERROR;
                  kfree_skb(ns);
                  goto err;
            }

            kfree_skb(skb);
            skb = ns;
            skb_put(skb, len);
            skb_pull(skb, 2); /* pull off the A/C bytes */

      } else {
            /* Uncompressed frame - pass to decompressor so it
               can update its dictionary if necessary. */
            if (ppp->rcomp->incomp)
                  ppp->rcomp->incomp(ppp->rc_state, skb->data - 2,
                                 skb->len + 2);
      }

      return skb;

 err:
      ppp->rstate |= SC_DC_ERROR;
      ppp_receive_error(ppp);
      return skb;
}

#ifdef CONFIG_PPP_MULTILINK
/*
 * Receive a multilink frame.
 * We put it on the reconstruction queue and then pull off
 * as many completed frames as we can.
 */
static void
ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
{
      u32 mask, seq;
      struct channel *ch;
      int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;

      if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
            goto err;         /* no good, throw it away */

      /* Decode sequence number and begin/end bits */
      if (ppp->flags & SC_MP_SHORTSEQ) {
            seq = ((skb->data[2] & 0x0f) << 8) | skb->data[3];
            mask = 0xfff;
      } else {
            seq = (skb->data[3] << 16) | (skb->data[4] << 8)| skb->data[5];
            mask = 0xffffff;
      }
      skb->BEbits = skb->data[2];
      skb_pull(skb, mphdrlen);      /* pull off PPP and MP headers */

      /*
       * Do protocol ID decompression on the first fragment of each packet.
       */
      if ((skb->BEbits & B) && (skb->data[0] & 1))
            *skb_push(skb, 1) = 0;

      /*
       * Expand sequence number to 32 bits, making it as close
       * as possible to ppp->minseq.
       */
      seq |= ppp->minseq & ~mask;
      if ((int)(ppp->minseq - seq) > (int)(mask >> 1))
            seq += mask + 1;
      else if ((int)(seq - ppp->minseq) > (int)(mask >> 1))
            seq -= mask + 1;  /* should never happen */
      skb->sequence = seq;
      pch->lastseq = seq;

      /*
       * If this packet comes before the next one we were expecting,
       * drop it.
       */
      if (seq_before(seq, ppp->nextseq)) {
            kfree_skb(skb);
            ++ppp->dev->stats.rx_dropped;
            ppp_receive_error(ppp);
            return;
      }

      /*
       * Reevaluate minseq, the minimum over all channels of the
       * last sequence number received on each channel.  Because of
       * the increasing sequence number rule, we know that any fragment
       * before `minseq' which hasn't arrived is never going to arrive.
       * The list of channels can't change because we have the receive
       * side of the ppp unit locked.
       */
      list_for_each_entry(ch, &ppp->channels, clist) {
            if (seq_before(ch->lastseq, seq))
                  seq = ch->lastseq;
      }
      if (seq_before(ppp->minseq, seq))
            ppp->minseq = seq;

      /* Put the fragment on the reconstruction queue */
      ppp_mp_insert(ppp, skb);

      /* If the queue is getting long, don't wait any longer for packets
         before the start of the queue. */
      if (skb_queue_len(&ppp->mrq) >= PPP_MP_MAX_QLEN) {
            struct sk_buff *skb = skb_peek(&ppp->mrq);
            if (seq_before(ppp->minseq, skb->sequence))
                  ppp->minseq = skb->sequence;
      }

      /* Pull completed packets off the queue and receive them. */
      while ((skb = ppp_mp_reconstruct(ppp)))
            ppp_receive_nonmp_frame(ppp, skb);

      return;

 err:
      kfree_skb(skb);
      ppp_receive_error(ppp);
}

/*
 * Insert a fragment on the MP reconstruction queue.
 * The queue is ordered by increasing sequence number.
 */
static void
ppp_mp_insert(struct ppp *ppp, struct sk_buff *skb)
{
      struct sk_buff *p;
      struct sk_buff_head *list = &ppp->mrq;
      u32 seq = skb->sequence;

      /* N.B. we don't need to lock the list lock because we have the
         ppp unit receive-side lock. */
      skb_queue_walk(list, p) {
            if (seq_before(seq, p->sequence))
                  break;
      }
      __skb_queue_before(list, p, skb);
}

/*
 * Reconstruct a packet from the MP fragment queue.
 * We go through increasing sequence numbers until we find a
 * complete packet, or we get to the sequence number for a fragment
 * which hasn't arrived but might still do so.
 */
static struct sk_buff *
ppp_mp_reconstruct(struct ppp *ppp)
{
      u32 seq = ppp->nextseq;
      u32 minseq = ppp->minseq;
      struct sk_buff_head *list = &ppp->mrq;
      struct sk_buff *p, *next;
      struct sk_buff *head, *tail;
      struct sk_buff *skb = NULL;
      int lost = 0, len = 0;

      if (ppp->mrru == 0)     /* do nothing until mrru is set */
            return NULL;
      head = list->next;
      tail = NULL;
      for (p = head; p != (struct sk_buff *) list; p = next) {
            next = p->next;
            if (seq_before(p->sequence, seq)) {
                  /* this can't happen, anyway ignore the skb */
                  printk(KERN_ERR "ppp_mp_reconstruct bad seq %u < %u\n",
                         p->sequence, seq);
                  head = next;
                  continue;
            }
            if (p->sequence != seq) {
                  /* Fragment `seq' is missing.  If it is after
                     minseq, it might arrive later, so stop here. */
                  if (seq_after(seq, minseq))
                        break;
                  /* Fragment `seq' is lost, keep going. */
                  lost = 1;
                  seq = seq_before(minseq, p->sequence)?
                        minseq + 1: p->sequence;
                  next = p;
                  continue;
            }

            /*
             * At this point we know that all the fragments from
             * ppp->nextseq to seq are either present or lost.
             * Also, there are no complete packets in the queue
             * that have no missing fragments and end before this
             * fragment.
             */

            /* B bit set indicates this fragment starts a packet */
            if (p->BEbits & B) {
                  head = p;
                  lost = 0;
                  len = 0;
            }

            len += p->len;

            /* Got a complete packet yet? */
            if (lost == 0 && (p->BEbits & E) && (head->BEbits & B)) {
                  if (len > ppp->mrru + 2) {
                        ++ppp->dev->stats.rx_length_errors;
                        printk(KERN_DEBUG "PPP: reconstructed packet"
                               " is too long (%d)\n", len);
                  } else if (p == head) {
                        /* fragment is complete packet - reuse skb */
                        tail = p;
                        skb = skb_get(p);
                        break;
                  } else if ((skb = dev_alloc_skb(len)) == NULL) {
                        ++ppp->dev->stats.rx_missed_errors;
                        printk(KERN_DEBUG "PPP: no memory for "
                               "reconstructed packet");
                  } else {
                        tail = p;
                        break;
                  }
                  ppp->nextseq = seq + 1;
            }

            /*
             * If this is the ending fragment of a packet,
             * and we haven't found a complete valid packet yet,
             * we can discard up to and including this fragment.
             */
            if (p->BEbits & E)
                  head = next;

            ++seq;
      }

      /* If we have a complete packet, copy it all into one skb. */
      if (tail != NULL) {
            /* If we have discarded any fragments,
               signal a receive error. */
            if (head->sequence != ppp->nextseq) {
                  if (ppp->debug & 1)
                        printk(KERN_DEBUG "  missed pkts %u..%u\n",
                               ppp->nextseq, head->sequence-1);
                  ++ppp->dev->stats.rx_dropped;
                  ppp_receive_error(ppp);
            }

            if (head != tail)
                  /* copy to a single skb */
                  for (p = head; p != tail->next; p = p->next)
                        skb_copy_bits(p, 0, skb_put(skb, p->len), p->len);
            ppp->nextseq = tail->sequence + 1;
            head = tail->next;
      }

      /* Discard all the skbuffs that we have copied the data out of
         or that we can't use. */
      while ((p = list->next) != head) {
            __skb_unlink(p, list);
            kfree_skb(p);
      }

      return skb;
}
#endif /* CONFIG_PPP_MULTILINK */

/*
 * Channel interface.
 */

/* Create a new, unattached ppp channel. */
int ppp_register_channel(struct ppp_channel *chan)
{
      return ppp_register_net_channel(current->nsproxy->net_ns, chan);
}

/* Create a new, unattached ppp channel for specified net. */
int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
{
      struct channel *pch;
      struct ppp_net *pn;

      pch = kzalloc(sizeof(struct channel), GFP_KERNEL);
      if (!pch)
            return -ENOMEM;

      pn = ppp_pernet(net);

      pch->ppp = NULL;
      pch->chan = chan;
      pch->chan_net = net;
      chan->ppp = pch;
      init_ppp_file(&pch->file, CHANNEL);
      pch->file.hdrlen = chan->hdrlen;
#ifdef CONFIG_PPP_MULTILINK
      pch->lastseq = -1;
#endif /* CONFIG_PPP_MULTILINK */
      init_rwsem(&pch->chan_sem);
      spin_lock_init(&pch->downl);
      rwlock_init(&pch->upl);

      spin_lock_bh(&pn->all_channels_lock);
      pch->file.index = ++pn->last_channel_index;
      list_add(&pch->list, &pn->new_channels);
      atomic_inc(&channel_count);
      spin_unlock_bh(&pn->all_channels_lock);

      return 0;
}

/*
 * Return the index of a channel.
 */
int ppp_channel_index(struct ppp_channel *chan)
{
      struct channel *pch = chan->ppp;

      if (pch)
            return pch->file.index;
      return -1;
}

/*
 * Return the PPP unit number to which a channel is connected.
 */
int ppp_unit_number(struct ppp_channel *chan)
{
      struct channel *pch = chan->ppp;
      int unit = -1;

      if (pch) {
            read_lock_bh(&pch->upl);
            if (pch->ppp)
                  unit = pch->ppp->file.index;
            read_unlock_bh(&pch->upl);
      }
      return unit;
}

/*
 * Disconnect a channel from the generic layer.
 * This must be called in process context.
 */
void
ppp_unregister_channel(struct ppp_channel *chan)
{
      struct channel *pch = chan->ppp;
      struct ppp_net *pn;

      if (!pch)
            return;           /* should never happen */

      chan->ppp = NULL;

      /*
       * This ensures that we have returned from any calls into the
       * the channel's start_xmit or ioctl routine before we proceed.
       */
      down_write(&pch->chan_sem);
      spin_lock_bh(&pch->downl);
      pch->chan = NULL;
      spin_unlock_bh(&pch->downl);
      up_write(&pch->chan_sem);
      ppp_disconnect_channel(pch);

      pn = ppp_pernet(pch->chan_net);
      spin_lock_bh(&pn->all_channels_lock);
      list_del(&pch->list);
      spin_unlock_bh(&pn->all_channels_lock);

      pch->file.dead = 1;
      wake_up_interruptible(&pch->file.rwait);
      if (atomic_dec_and_test(&pch->file.refcnt))
            ppp_destroy_channel(pch);
}

/*
 * Callback from a channel when it can accept more to transmit.
 * This should be called at BH/softirq level, not interrupt level.
 */
void
ppp_output_wakeup(struct ppp_channel *chan)
{
      struct channel *pch = chan->ppp;

      if (!pch)
            return;
      ppp_channel_push(pch);
}

/*
 * Compression control.
 */

/* Process the PPPIOCSCOMPRESS ioctl. */
static int
ppp_set_compress(struct ppp *ppp, unsigned long arg)
{
      int err;
      struct compressor *cp, *ocomp;
      struct ppp_option_data data;
      void *state, *ostate;
      unsigned char ccp_option[CCP_MAX_OPTION_LENGTH];

      err = -EFAULT;
      if (copy_from_user(&data, (void __user *) arg, sizeof(data))
          || (data.length <= CCP_MAX_OPTION_LENGTH
            && copy_from_user(ccp_option, (void __user *) data.ptr, data.length)))
            goto out;
      err = -EINVAL;
      if (data.length > CCP_MAX_OPTION_LENGTH
          || ccp_option[1] < 2 || ccp_option[1] > data.length)
            goto out;

      cp = try_then_request_module(
            find_compressor(ccp_option[0]),
            "ppp-compress-%d", ccp_option[0]);
      if (!cp)
            goto out;

      err = -ENOBUFS;
      if (data.transmit) {
            state = cp->comp_alloc(ccp_option, data.length);
            if (state) {
                  ppp_xmit_lock(ppp);
                  ppp->xstate &= ~SC_COMP_RUN;
                  ocomp = ppp->xcomp;
                  ostate = ppp->xc_state;
                  ppp->xcomp = cp;
                  ppp->xc_state = state;
                  ppp_xmit_unlock(ppp);
                  if (ostate) {
                        ocomp->comp_free(ostate);
                        module_put(ocomp->owner);
                  }
                  err = 0;
            } else
                  module_put(cp->owner);

      } else {
            state = cp->decomp_alloc(ccp_option, data.length);
            if (state) {
                  ppp_recv_lock(ppp);
                  ppp->rstate &= ~SC_DECOMP_RUN;
                  ocomp = ppp->rcomp;
                  ostate = ppp->rc_state;
                  ppp->rcomp = cp;
                  ppp->rc_state = state;
                  ppp_recv_unlock(ppp);
                  if (ostate) {
                        ocomp->decomp_free(ostate);
                        module_put(ocomp->owner);
                  }
                  err = 0;
            } else
                  module_put(cp->owner);
      }

 out:
      return err;
}

/*
 * Look at a CCP packet and update our state accordingly.
 * We assume the caller has the xmit or recv path locked.
 */
static void
ppp_ccp_peek(struct ppp *ppp, struct sk_buff *skb, int inbound)
{
      unsigned char *dp;
      int len;

      if (!pskb_may_pull(skb, CCP_HDRLEN + 2))
            return;     /* no header */
      dp = skb->data + 2;

      switch (CCP_CODE(dp)) {
      case CCP_CONFREQ:

            /* A ConfReq starts negotiation of compression
             * in one direction of transmission,
             * and hence brings it down...but which way?
             *
             * Remember:
             * A ConfReq indicates what the sender would like to receive
             */
            if(inbound)
                  /* He is proposing what I should send */
                  ppp->xstate &= ~SC_COMP_RUN;
            else
                  /* I am proposing to what he should send */
                  ppp->rstate &= ~SC_DECOMP_RUN;

            break;

      case CCP_TERMREQ:
      case CCP_TERMACK:
            /*
             * CCP is going down, both directions of transmission
             */
            ppp->rstate &= ~SC_DECOMP_RUN;
            ppp->xstate &= ~SC_COMP_RUN;
            break;

      case CCP_CONFACK:
            if ((ppp->flags & (SC_CCP_OPEN | SC_CCP_UP)) != SC_CCP_OPEN)
                  break;
            len = CCP_LENGTH(dp);
            if (!pskb_may_pull(skb, len + 2))
                  return;           /* too short */
            dp += CCP_HDRLEN;
            len -= CCP_HDRLEN;
            if (len < CCP_OPT_MINLEN || len < CCP_OPT_LENGTH(dp))
                  break;
            if (inbound) {
                  /* we will start receiving compressed packets */
                  if (!ppp->rc_state)
                        break;
                  if (ppp->rcomp->decomp_init(ppp->rc_state, dp, len,
                              ppp->file.index, 0, ppp->mru, ppp->debug)) {
                        ppp->rstate |= SC_DECOMP_RUN;
                        ppp->rstate &= ~(SC_DC_ERROR | SC_DC_FERROR);
                  }
            } else {
                  /* we will soon start sending compressed packets */
                  if (!ppp->xc_state)
                        break;
                  if (ppp->xcomp->comp_init(ppp->xc_state, dp, len,
                              ppp->file.index, 0, ppp->debug))
                        ppp->xstate |= SC_COMP_RUN;
            }
            break;

      case CCP_RESETACK:
            /* reset the [de]compressor */
            if ((ppp->flags & SC_CCP_UP) == 0)
                  break;
            if (inbound) {
                  if (ppp->rc_state && (ppp->rstate & SC_DECOMP_RUN)) {
                        ppp->rcomp->decomp_reset(ppp->rc_state);
                        ppp->rstate &= ~SC_DC_ERROR;
                  }
            } else {
                  if (ppp->xc_state && (ppp->xstate & SC_COMP_RUN))
                        ppp->xcomp->comp_reset(ppp->xc_state);
            }
            break;
      }
}

/* Free up compression resources. */
static void
ppp_ccp_closed(struct ppp *ppp)
{
      void *xstate, *rstate;
      struct compressor *xcomp, *rcomp;

      ppp_lock(ppp);
      ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP);
      ppp->xstate = 0;
      xcomp = ppp->xcomp;
      xstate = ppp->xc_state;
      ppp->xc_state = NULL;
      ppp->rstate = 0;
      rcomp = ppp->rcomp;
      rstate = ppp->rc_state;
      ppp->rc_state = NULL;
      ppp_unlock(ppp);

      if (xstate) {
            xcomp->comp_free(xstate);
            module_put(xcomp->owner);
      }
      if (rstate) {
            rcomp->decomp_free(rstate);
            module_put(rcomp->owner);
      }
}

/* List of compressors. */
static LIST_HEAD(compressor_list);
static DEFINE_SPINLOCK(compressor_list_lock);

02417 struct compressor_entry {
      struct list_head list;
      struct compressor *comp;
};

static struct compressor_entry *
find_comp_entry(int proto)
{
      struct compressor_entry *ce;

      list_for_each_entry(ce, &compressor_list, list) {
            if (ce->comp->compress_proto == proto)
                  return ce;
      }
      return NULL;
}

/* Register a compressor */
int
ppp_register_compressor(struct compressor *cp)
{
      struct compressor_entry *ce;
      int ret;
      spin_lock(&compressor_list_lock);
      ret = -EEXIST;
      if (find_comp_entry(cp->compress_proto))
            goto out;
      ret = -ENOMEM;
      ce = kmalloc(sizeof(struct compressor_entry), GFP_ATOMIC);
      if (!ce)
            goto out;
      ret = 0;
      ce->comp = cp;
      list_add(&ce->list, &compressor_list);
 out:
      spin_unlock(&compressor_list_lock);
      return ret;
}

/* Unregister a compressor */
void
ppp_unregister_compressor(struct compressor *cp)
{
      struct compressor_entry *ce;

      spin_lock(&compressor_list_lock);
      ce = find_comp_entry(cp->compress_proto);
      if (ce && ce->comp == cp) {
            list_del(&ce->list);
            kfree(ce);
      }
      spin_unlock(&compressor_list_lock);
}

/* Find a compressor. */
static struct compressor *
find_compressor(int type)
{
      struct compressor_entry *ce;
      struct compressor *cp = NULL;

      spin_lock(&compressor_list_lock);
      ce = find_comp_entry(type);
      if (ce) {
            cp = ce->comp;
            if (!try_module_get(cp->owner))
                  cp = NULL;
      }
      spin_unlock(&compressor_list_lock);
      return cp;
}

/*
 * Miscelleneous stuff.
 */

static void
ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
{
      struct slcompress *vj = ppp->vj;

      memset(st, 0, sizeof(*st));
      st->p.ppp_ipackets = ppp->dev->stats.rx_packets;
      st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
      st->p.ppp_ibytes = ppp->dev->stats.rx_bytes;
      st->p.ppp_opackets = ppp->dev->stats.tx_packets;
      st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
      st->p.ppp_obytes = ppp->dev->stats.tx_bytes;
      if (!vj)
            return;
      st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
      st->vj.vjs_compressed = vj->sls_o_compressed;
      st->vj.vjs_searches = vj->sls_o_searches;
      st->vj.vjs_misses = vj->sls_o_misses;
      st->vj.vjs_errorin = vj->sls_i_error;
      st->vj.vjs_tossed = vj->sls_i_tossed;
      st->vj.vjs_uncompressedin = vj->sls_i_uncompressed;
      st->vj.vjs_compressedin = vj->sls_i_compressed;
}

/*
 * Stuff for handling the lists of ppp units and channels
 * and for initialization.
 */

/*
 * Create a new ppp interface unit.  Fails if it can't allocate memory
 * or if there is already a unit with the requested number.
 * unit == -1 means allocate a new number.
 */
static struct ppp *
ppp_create_interface(struct net *net, int unit, int *retp)
{
      struct ppp *ppp;
      struct ppp_net *pn;
      struct net_device *dev = NULL;
      int ret = -ENOMEM;
      int i;

      dev = alloc_netdev(sizeof(struct ppp), "", ppp_setup);
      if (!dev)
            goto out1;

      pn = ppp_pernet(net);

      ppp = netdev_priv(dev);
      ppp->dev = dev;
      ppp->mru = PPP_MRU;
      init_ppp_file(&ppp->file, INTERFACE);
      ppp->file.hdrlen = PPP_HDRLEN - 2;  /* don't count proto bytes */
      for (i = 0; i < NUM_NP; ++i)
            ppp->npmode[i] = NPMODE_PASS;
      INIT_LIST_HEAD(&ppp->channels);
      spin_lock_init(&ppp->rlock);
      spin_lock_init(&ppp->wlock);
#ifdef CONFIG_PPP_MULTILINK
      ppp->minseq = -1;
      skb_queue_head_init(&ppp->mrq);
#endif /* CONFIG_PPP_MULTILINK */

      /*
       * drum roll: don't forget to set
       * the net device is belong to
       */
      dev_net_set(dev, net);

      ret = -EEXIST;
      mutex_lock(&pn->all_ppp_mutex);

      if (unit < 0) {
            unit = unit_get(&pn->units_idr, ppp);
            if (unit < 0) {
                  *retp = unit;
                  goto out2;
            }
      } else {
            if (unit_find(&pn->units_idr, unit))
                  goto out2; /* unit already exists */
            /*
             * if caller need a specified unit number
             * lets try to satisfy him, otherwise --
             * he should better ask us for new unit number
             *
             * NOTE: yes I know that returning EEXIST it's not
             * fair but at least pppd will ask us to allocate
             * new unit in this case so user is happy :)
             */
            unit = unit_set(&pn->units_idr, ppp, unit);
            if (unit < 0)
                  goto out2;
      }

      /* Initialize the new ppp unit */
      ppp->file.index = unit;
      sprintf(dev->name, "ppp%d", unit);

      ret = register_netdev(dev);
      if (ret != 0) {
            unit_put(&pn->units_idr, unit);
            printk(KERN_ERR "PPP: couldn't register device %s (%d)\n",
                   dev->name, ret);
            goto out2;
      }

      ppp->ppp_net = net;

      atomic_inc(&ppp_unit_count);
      mutex_unlock(&pn->all_ppp_mutex);

      *retp = 0;
      return ppp;

out2:
      mutex_unlock(&pn->all_ppp_mutex);
      free_netdev(dev);
out1:
      *retp = ret;
      return NULL;
}

/*
 * Initialize a ppp_file structure.
 */
static void
init_ppp_file(struct ppp_file *pf, int kind)
{
      pf->kind = kind;
      skb_queue_head_init(&pf->xq);
      skb_queue_head_init(&pf->rq);
      atomic_set(&pf->refcnt, 1);
      init_waitqueue_head(&pf->rwait);
}

/*
 * Take down a ppp interface unit - called when the owning file
 * (the one that created the unit) is closed or detached.
 */
static void ppp_shutdown_interface(struct ppp *ppp)
{
      struct ppp_net *pn;

      pn = ppp_pernet(ppp->ppp_net);
      mutex_lock(&pn->all_ppp_mutex);

      /* This will call dev_close() for us. */
      ppp_lock(ppp);
      if (!ppp->closing) {
            ppp->closing = 1;
            ppp_unlock(ppp);
            unregister_netdev(ppp->dev);
      } else
            ppp_unlock(ppp);

      unit_put(&pn->units_idr, ppp->file.index);
      ppp->file.dead = 1;
      ppp->owner = NULL;
      wake_up_interruptible(&ppp->file.rwait);

      mutex_unlock(&pn->all_ppp_mutex);
}

/*
 * Free the memory used by a ppp unit.  This is only called once
 * there are no channels connected to the unit and no file structs
 * that reference the unit.
 */
static void ppp_destroy_interface(struct ppp *ppp)
{
      atomic_dec(&ppp_unit_count);

      if (!ppp->file.dead || ppp->n_channels) {
            /* "can't happen" */
            printk(KERN_ERR "ppp: destroying ppp struct %p but dead=%d "
                   "n_channels=%d !\n", ppp, ppp->file.dead,
                   ppp->n_channels);
            return;
      }

      ppp_ccp_closed(ppp);
      if (ppp->vj) {
            slhc_free(ppp->vj);
            ppp->vj = NULL;
      }
      skb_queue_purge(&ppp->file.xq);
      skb_queue_purge(&ppp->file.rq);
#ifdef CONFIG_PPP_MULTILINK
      skb_queue_purge(&ppp->mrq);
#endif /* CONFIG_PPP_MULTILINK */
#ifdef CONFIG_PPP_FILTER
      kfree(ppp->pass_filter);
      ppp->pass_filter = NULL;
      kfree(ppp->active_filter);
      ppp->active_filter = NULL;
#endif /* CONFIG_PPP_FILTER */

      kfree_skb(ppp->xmit_pending);

      free_netdev(ppp->dev);
}

/*
 * Locate an existing ppp unit.
 * The caller should have locked the all_ppp_mutex.
 */
static struct ppp *
ppp_find_unit(struct ppp_net *pn, int unit)
{
      return unit_find(&pn->units_idr, unit);
}

/*
 * Locate an existing ppp channel.
 * The caller should have locked the all_channels_lock.
 * First we look in the new_channels list, then in the
 * all_channels list.  If found in the new_channels list,
 * we move it to the all_channels list.  This is for speed
 * when we have a lot of channels in use.
 */
static struct channel *
ppp_find_channel(struct ppp_net *pn, int unit)
{
      struct channel *pch;

      list_for_each_entry(pch, &pn->new_channels, list) {
            if (pch->file.index == unit) {
                  list_move(&pch->list, &pn->all_channels);
                  return pch;
            }
      }

      list_for_each_entry(pch, &pn->all_channels, list) {
            if (pch->file.index == unit)
                  return pch;
      }

      return NULL;
}

/*
 * Connect a PPP channel to a PPP interface unit.
 */
static int
ppp_connect_channel(struct channel *pch, int unit)
{
      struct ppp *ppp;
      struct ppp_net *pn;
      int ret = -ENXIO;
      int hdrlen;

      pn = ppp_pernet(pch->chan_net);

      mutex_lock(&pn->all_ppp_mutex);
      ppp = ppp_find_unit(pn, unit);
      if (!ppp)
            goto out;
      write_lock_bh(&pch->upl);
      ret = -EINVAL;
      if (pch->ppp)
            goto outl;

      ppp_lock(ppp);
      if (pch->file.hdrlen > ppp->file.hdrlen)
            ppp->file.hdrlen = pch->file.hdrlen;
      hdrlen = pch->file.hdrlen + 2;      /* for protocol bytes */
      if (hdrlen > ppp->dev->hard_header_len)
            ppp->dev->hard_header_len = hdrlen;
      list_add_tail(&pch->clist, &ppp->channels);
      ++ppp->n_channels;
      pch->ppp = ppp;
      atomic_inc(&ppp->file.refcnt);
      ppp_unlock(ppp);
      ret = 0;

 outl:
      write_unlock_bh(&pch->upl);
 out:
      mutex_unlock(&pn->all_ppp_mutex);
      return ret;
}

/*
 * Disconnect a channel from its ppp unit.
 */
static int
ppp_disconnect_channel(struct channel *pch)
{
      struct ppp *ppp;
      int err = -EINVAL;

      write_lock_bh(&pch->upl);
      ppp = pch->ppp;
      pch->ppp = NULL;
      write_unlock_bh(&pch->upl);
      if (ppp) {
            /* remove it from the ppp unit's list */
            ppp_lock(ppp);
            list_del(&pch->clist);
            if (--ppp->n_channels == 0)
                  wake_up_interruptible(&ppp->file.rwait);
            ppp_unlock(ppp);
            if (atomic_dec_and_test(&ppp->file.refcnt))
                  ppp_destroy_interface(ppp);
            err = 0;
      }
      return err;
}

/*
 * Free up the resources used by a ppp channel.
 */
static void ppp_destroy_channel(struct channel *pch)
{
      atomic_dec(&channel_count);

      if (!pch->file.dead) {
            /* "can't happen" */
            printk(KERN_ERR "ppp: destroying undead channel %p !\n",
                   pch);
            return;
      }
      skb_queue_purge(&pch->file.xq);
      skb_queue_purge(&pch->file.rq);
      kfree(pch);
}

static void __exit ppp_cleanup(void)
{
      /* should never happen */
      if (atomic_read(&ppp_unit_count) || atomic_read(&channel_count))
            printk(KERN_ERR "PPP: removing module but units remain!\n");
      unregister_chrdev(PPP_MAJOR, "ppp");
      device_destroy(ppp_class, MKDEV(PPP_MAJOR, 0));
      class_destroy(ppp_class);
      unregister_pernet_gen_device(ppp_net_id, &ppp_net_ops);
}

/*
 * Units handling. Caller must protect concurrent access
 * by holding all_ppp_mutex
 */

/* associate pointer with specified number */
static int unit_set(struct idr *p, void *ptr, int n)
{
      int unit, err;

again:
      if (!idr_pre_get(p, GFP_KERNEL)) {
            printk(KERN_ERR "PPP: No free memory for idr\n");
            return -ENOMEM;
      }

      err = idr_get_new_above(p, ptr, n, &unit);
      if (err == -EAGAIN)
            goto again;

      if (unit != n) {
            idr_remove(p, unit);
            return -EINVAL;
      }

      return unit;
}

/* get new free unit number and associate pointer with it */
static int unit_get(struct idr *p, void *ptr)
{
      int unit, err;

again:
      if (!idr_pre_get(p, GFP_KERNEL)) {
            printk(KERN_ERR "PPP: No free memory for idr\n");
            return -ENOMEM;
      }

      err = idr_get_new_above(p, ptr, 0, &unit);
      if (err == -EAGAIN)
            goto again;

      return unit;
}

/* put unit number back to a pool */
static void unit_put(struct idr *p, int n)
{
      idr_remove(p, n);
}

/* get pointer associated with the number */
static void *unit_find(struct idr *p, int n)
{
      return idr_find(p, n);
}

/* Module/initialization stuff */

module_init(ppp_init);
module_exit(ppp_cleanup);

EXPORT_SYMBOL(ppp_register_net_channel);
EXPORT_SYMBOL(ppp_register_channel);
EXPORT_SYMBOL(ppp_unregister_channel);
EXPORT_SYMBOL(ppp_channel_index);
EXPORT_SYMBOL(ppp_unit_number);
EXPORT_SYMBOL(ppp_input);
EXPORT_SYMBOL(ppp_input_error);
EXPORT_SYMBOL(ppp_output_wakeup);
EXPORT_SYMBOL(ppp_register_compressor);
EXPORT_SYMBOL(ppp_unregister_compressor);
MODULE_LICENSE("GPL");
MODULE_ALIAS_CHARDEV_MAJOR(PPP_MAJOR);
MODULE_ALIAS("/dev/ppp");

Generated by  Doxygen 1.6.0   Back to index