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clip.c

/* net/atm/clip.c - RFC1577 Classical IP over ATM */

/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */

#include <linux/string.h>
#include <linux/errno.h>
#include <linux/kernel.h> /* for UINT_MAX */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/wait.h>
#include <linux/timer.h>
#include <linux/if_arp.h> /* for some manifest constants */
#include <linux/notifier.h>
#include <linux/atm.h>
#include <linux/atmdev.h>
#include <linux/atmclip.h>
#include <linux/atmarp.h>
#include <linux/capability.h>
#include <linux/ip.h> /* for net/route.h */
#include <linux/in.h> /* for struct sockaddr_in */
#include <linux/if.h> /* for IFF_UP */
#include <linux/inetdevice.h>
#include <linux/bitops.h>
#include <linux/poison.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/rcupdate.h>
#include <linux/jhash.h>
#include <net/route.h> /* for struct rtable and routing */
#include <net/icmp.h> /* icmp_send */
#include <asm/param.h> /* for HZ */
#include <asm/byteorder.h> /* for htons etc. */
#include <asm/system.h> /* save/restore_flags */
#include <asm/uaccess.h>
#include <asm/atomic.h>

#include "common.h"
#include "resources.h"
#include <net/atmclip.h>

static struct net_device *clip_devs;
static struct atm_vcc *atmarpd;
static struct neigh_table clip_tbl;
static struct timer_list idle_timer;

static int to_atmarpd(enum atmarp_ctrl_type type, int itf, __be32 ip)
{
      struct sock *sk;
      struct atmarp_ctrl *ctrl;
      struct sk_buff *skb;

      pr_debug("to_atmarpd(%d)\n", type);
      if (!atmarpd)
            return -EUNATCH;
      skb = alloc_skb(sizeof(struct atmarp_ctrl),GFP_ATOMIC);
      if (!skb)
            return -ENOMEM;
      ctrl = (struct atmarp_ctrl *) skb_put(skb,sizeof(struct atmarp_ctrl));
      ctrl->type = type;
      ctrl->itf_num = itf;
      ctrl->ip = ip;
      atm_force_charge(atmarpd, skb->truesize);

      sk = sk_atm(atmarpd);
      skb_queue_tail(&sk->sk_receive_queue, skb);
      sk->sk_data_ready(sk, skb->len);
      return 0;
}

static void link_vcc(struct clip_vcc *clip_vcc, struct atmarp_entry *entry)
{
      pr_debug("link_vcc %p to entry %p (neigh %p)\n", clip_vcc, entry,
            entry->neigh);
      clip_vcc->entry = entry;
      clip_vcc->xoff = 0;     /* @@@ may overrun buffer by one packet */
      clip_vcc->next = entry->vccs;
      entry->vccs = clip_vcc;
      entry->neigh->used = jiffies;
}

static void unlink_clip_vcc(struct clip_vcc *clip_vcc)
{
      struct atmarp_entry *entry = clip_vcc->entry;
      struct clip_vcc **walk;

      if (!entry) {
            printk(KERN_CRIT "!clip_vcc->entry (clip_vcc %p)\n", clip_vcc);
            return;
      }
      netif_tx_lock_bh(entry->neigh->dev);      /* block clip_start_xmit() */
      entry->neigh->used = jiffies;
      for (walk = &entry->vccs; *walk; walk = &(*walk)->next)
            if (*walk == clip_vcc) {
                  int error;

                  *walk = clip_vcc->next; /* atomic */
                  clip_vcc->entry = NULL;
                  if (clip_vcc->xoff)
                        netif_wake_queue(entry->neigh->dev);
                  if (entry->vccs)
                        goto out;
                  entry->expires = jiffies - 1;
                  /* force resolution or expiration */
                  error = neigh_update(entry->neigh, NULL, NUD_NONE,
                                   NEIGH_UPDATE_F_ADMIN);
                  if (error)
                        printk(KERN_CRIT "unlink_clip_vcc: "
                               "neigh_update failed with %d\n", error);
                  goto out;
            }
      printk(KERN_CRIT "ATMARP: unlink_clip_vcc failed (entry %p, vcc "
             "0x%p)\n", entry, clip_vcc);
      out:
      netif_tx_unlock_bh(entry->neigh->dev);
}

/* The neighbour entry n->lock is held. */
static int neigh_check_cb(struct neighbour *n)
{
      struct atmarp_entry *entry = NEIGH2ENTRY(n);
      struct clip_vcc *cv;

      for (cv = entry->vccs; cv; cv = cv->next) {
            unsigned long exp = cv->last_use + cv->idle_timeout;

            if (cv->idle_timeout && time_after(jiffies, exp)) {
                  pr_debug("releasing vcc %p->%p of entry %p\n",
                        cv, cv->vcc, entry);
                  vcc_release_async(cv->vcc, -ETIMEDOUT);
            }
      }

      if (entry->vccs || time_before(jiffies, entry->expires))
            return 0;

      if (atomic_read(&n->refcnt) > 1) {
            struct sk_buff *skb;

            pr_debug("destruction postponed with ref %d\n",
                  atomic_read(&n->refcnt));

            while ((skb = skb_dequeue(&n->arp_queue)) != NULL)
                  dev_kfree_skb(skb);

            return 0;
      }

      pr_debug("expired neigh %p\n", n);
      return 1;
}

static void idle_timer_check(unsigned long dummy)
{
      write_lock(&clip_tbl.lock);
      __neigh_for_each_release(&clip_tbl, neigh_check_cb);
      mod_timer(&idle_timer, jiffies + CLIP_CHECK_INTERVAL * HZ);
      write_unlock(&clip_tbl.lock);
}

static int clip_arp_rcv(struct sk_buff *skb)
{
      struct atm_vcc *vcc;

      pr_debug("clip_arp_rcv\n");
      vcc = ATM_SKB(skb)->vcc;
      if (!vcc || !atm_charge(vcc, skb->truesize)) {
            dev_kfree_skb_any(skb);
            return 0;
      }
      pr_debug("pushing to %p\n", vcc);
      pr_debug("using %p\n", CLIP_VCC(vcc)->old_push);
      CLIP_VCC(vcc)->old_push(vcc, skb);
      return 0;
}

static const unsigned char llc_oui[] = {
      0xaa, /* DSAP: non-ISO */
      0xaa, /* SSAP: non-ISO */
      0x03, /* Ctrl: Unnumbered Information Command PDU */
      0x00, /* OUI: EtherType */
      0x00,
      0x00
};

static void clip_push(struct atm_vcc *vcc, struct sk_buff *skb)
{
      struct clip_vcc *clip_vcc = CLIP_VCC(vcc);

      pr_debug("clip push\n");
      if (!skb) {
            pr_debug("removing VCC %p\n", clip_vcc);
            if (clip_vcc->entry)
                  unlink_clip_vcc(clip_vcc);
            clip_vcc->old_push(vcc, NULL);      /* pass on the bad news */
            kfree(clip_vcc);
            return;
      }
      atm_return(vcc, skb->truesize);
      skb->dev = clip_vcc->entry ? clip_vcc->entry->neigh->dev : clip_devs;
      /* clip_vcc->entry == NULL if we don't have an IP address yet */
      if (!skb->dev) {
            dev_kfree_skb_any(skb);
            return;
      }
      ATM_SKB(skb)->vcc = vcc;
      skb_reset_mac_header(skb);
      if (!clip_vcc->encap
          || skb->len < RFC1483LLC_LEN
          || memcmp(skb->data, llc_oui, sizeof (llc_oui)))
            skb->protocol = htons(ETH_P_IP);
      else {
            skb->protocol = ((__be16 *) skb->data)[3];
            skb_pull(skb, RFC1483LLC_LEN);
            if (skb->protocol == htons(ETH_P_ARP)) {
                  PRIV(skb->dev)->stats.rx_packets++;
                  PRIV(skb->dev)->stats.rx_bytes += skb->len;
                  clip_arp_rcv(skb);
                  return;
            }
      }
      clip_vcc->last_use = jiffies;
      PRIV(skb->dev)->stats.rx_packets++;
      PRIV(skb->dev)->stats.rx_bytes += skb->len;
      memset(ATM_SKB(skb), 0, sizeof(struct atm_skb_data));
      netif_rx(skb);
}

/*
 * Note: these spinlocks _must_not_ block on non-SMP. The only goal is that
 * clip_pop is atomic with respect to the critical section in clip_start_xmit.
 */

static void clip_pop(struct atm_vcc *vcc, struct sk_buff *skb)
{
      struct clip_vcc *clip_vcc = CLIP_VCC(vcc);
      struct net_device *dev = skb->dev;
      int old;
      unsigned long flags;

      pr_debug("clip_pop(vcc %p)\n", vcc);
      clip_vcc->old_pop(vcc, skb);
      /* skb->dev == NULL in outbound ARP packets */
      if (!dev)
            return;
      spin_lock_irqsave(&PRIV(dev)->xoff_lock, flags);
      if (atm_may_send(vcc, 0)) {
            old = xchg(&clip_vcc->xoff, 0);
            if (old)
                  netif_wake_queue(dev);
      }
      spin_unlock_irqrestore(&PRIV(dev)->xoff_lock, flags);
}

static void clip_neigh_solicit(struct neighbour *neigh, struct sk_buff *skb)
{
      pr_debug("clip_neigh_solicit (neigh %p, skb %p)\n", neigh, skb);
      to_atmarpd(act_need, PRIV(neigh->dev)->number, NEIGH2ENTRY(neigh)->ip);
}

static void clip_neigh_error(struct neighbour *neigh, struct sk_buff *skb)
{
#ifndef CONFIG_ATM_CLIP_NO_ICMP
      icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
#endif
      kfree_skb(skb);
}

static struct neigh_ops clip_neigh_ops = {
      .family =         AF_INET,
      .solicit =        clip_neigh_solicit,
      .error_report =         clip_neigh_error,
      .output =         dev_queue_xmit,
      .connected_output =     dev_queue_xmit,
      .hh_output =            dev_queue_xmit,
      .queue_xmit =           dev_queue_xmit,
};

static int clip_constructor(struct neighbour *neigh)
{
      struct atmarp_entry *entry = NEIGH2ENTRY(neigh);
      struct net_device *dev = neigh->dev;
      struct in_device *in_dev;
      struct neigh_parms *parms;

      pr_debug("clip_constructor (neigh %p, entry %p)\n", neigh, entry);
      neigh->type = inet_addr_type(entry->ip);
      if (neigh->type != RTN_UNICAST)
            return -EINVAL;

      rcu_read_lock();
      in_dev = __in_dev_get_rcu(dev);
      if (!in_dev) {
            rcu_read_unlock();
            return -EINVAL;
      }

      parms = in_dev->arp_parms;
      __neigh_parms_put(neigh->parms);
      neigh->parms = neigh_parms_clone(parms);
      rcu_read_unlock();

      neigh->ops = &clip_neigh_ops;
      neigh->output = neigh->nud_state & NUD_VALID ?
          neigh->ops->connected_output : neigh->ops->output;
      entry->neigh = neigh;
      entry->vccs = NULL;
      entry->expires = jiffies - 1;
      return 0;
}

static u32 clip_hash(const void *pkey, const struct net_device *dev)
{
      return jhash_2words(*(u32 *) pkey, dev->ifindex, clip_tbl.hash_rnd);
}

static struct neigh_table clip_tbl = {
      .family     = AF_INET,
      .entry_size       = sizeof(struct neighbour)+sizeof(struct atmarp_entry),
      .key_len    = 4,
      .hash             = clip_hash,
      .constructor      = clip_constructor,
      .id         = "clip_arp_cache",

      /* parameters are copied from ARP ... */
      .parms = {
            .tbl              = &clip_tbl,
            .base_reachable_time    = 30 * HZ,
            .retrans_time           = 1 * HZ,
            .gc_staletime           = 60 * HZ,
            .reachable_time   = 30 * HZ,
            .delay_probe_time       = 5 * HZ,
            .queue_len        = 3,
            .ucast_probes           = 3,
            .mcast_probes           = 3,
            .anycast_delay          = 1 * HZ,
            .proxy_delay            = (8 * HZ) / 10,
            .proxy_qlen             = 64,
            .locktime         = 1 * HZ,
      },
      .gc_interval      = 30 * HZ,
      .gc_thresh1       = 128,
      .gc_thresh2       = 512,
      .gc_thresh3       = 1024,
};

/* @@@ copy bh locking from arp.c -- need to bh-enable atm code before */

/*
 * We play with the resolve flag: 0 and 1 have the usual meaning, but -1 means
 * to allocate the neighbour entry but not to ask atmarpd for resolution. Also,
 * don't increment the usage count. This is used to create entries in
 * clip_setentry.
 */

static int clip_encap(struct atm_vcc *vcc, int mode)
{
      CLIP_VCC(vcc)->encap = mode;
      return 0;
}

static int clip_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
      struct clip_priv *clip_priv = PRIV(dev);
      struct atmarp_entry *entry;
      struct atm_vcc *vcc;
      int old;
      unsigned long flags;

      pr_debug("clip_start_xmit (skb %p)\n", skb);
      if (!skb->dst) {
            printk(KERN_ERR "clip_start_xmit: skb->dst == NULL\n");
            dev_kfree_skb(skb);
            clip_priv->stats.tx_dropped++;
            return 0;
      }
      if (!skb->dst->neighbour) {
#if 0
            skb->dst->neighbour = clip_find_neighbour(skb->dst, 1);
            if (!skb->dst->neighbour) {
                  dev_kfree_skb(skb);     /* lost that one */
                  clip_priv->stats.tx_dropped++;
                  return 0;
            }
#endif
            printk(KERN_ERR "clip_start_xmit: NO NEIGHBOUR !\n");
            dev_kfree_skb(skb);
            clip_priv->stats.tx_dropped++;
            return 0;
      }
      entry = NEIGH2ENTRY(skb->dst->neighbour);
      if (!entry->vccs) {
            if (time_after(jiffies, entry->expires)) {
                  /* should be resolved */
                  entry->expires = jiffies + ATMARP_RETRY_DELAY * HZ;
                  to_atmarpd(act_need, PRIV(dev)->number, entry->ip);
            }
            if (entry->neigh->arp_queue.qlen < ATMARP_MAX_UNRES_PACKETS)
                  skb_queue_tail(&entry->neigh->arp_queue, skb);
            else {
                  dev_kfree_skb(skb);
                  clip_priv->stats.tx_dropped++;
            }
            return 0;
      }
      pr_debug("neigh %p, vccs %p\n", entry, entry->vccs);
      ATM_SKB(skb)->vcc = vcc = entry->vccs->vcc;
      pr_debug("using neighbour %p, vcc %p\n", skb->dst->neighbour, vcc);
      if (entry->vccs->encap) {
            void *here;

            here = skb_push(skb, RFC1483LLC_LEN);
            memcpy(here, llc_oui, sizeof(llc_oui));
            ((__be16 *) here)[3] = skb->protocol;
      }
      atomic_add(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc);
      ATM_SKB(skb)->atm_options = vcc->atm_options;
      entry->vccs->last_use = jiffies;
      pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, vcc, vcc->dev);
      old = xchg(&entry->vccs->xoff, 1);  /* assume XOFF ... */
      if (old) {
            printk(KERN_WARNING "clip_start_xmit: XOFF->XOFF transition\n");
            return 0;
      }
      clip_priv->stats.tx_packets++;
      clip_priv->stats.tx_bytes += skb->len;
      vcc->send(vcc, skb);
      if (atm_may_send(vcc, 0)) {
            entry->vccs->xoff = 0;
            return 0;
      }
      spin_lock_irqsave(&clip_priv->xoff_lock, flags);
      netif_stop_queue(dev);  /* XOFF -> throttle immediately */
      barrier();
      if (!entry->vccs->xoff)
            netif_start_queue(dev);
      /* Oh, we just raced with clip_pop. netif_start_queue should be
         good enough, because nothing should really be asleep because
         of the brief netif_stop_queue. If this isn't true or if it
         changes, use netif_wake_queue instead. */
      spin_unlock_irqrestore(&clip_priv->xoff_lock, flags);
      return 0;
}

static struct net_device_stats *clip_get_stats(struct net_device *dev)
{
      return &PRIV(dev)->stats;
}

static int clip_mkip(struct atm_vcc *vcc, int timeout)
{
      struct clip_vcc *clip_vcc;
      struct sk_buff *skb;
      struct sk_buff_head *rq;
      unsigned long flags;

      if (!vcc->push)
            return -EBADFD;
      clip_vcc = kmalloc(sizeof(struct clip_vcc), GFP_KERNEL);
      if (!clip_vcc)
            return -ENOMEM;
      pr_debug("mkip clip_vcc %p vcc %p\n", clip_vcc, vcc);
      clip_vcc->vcc = vcc;
      vcc->user_back = clip_vcc;
      set_bit(ATM_VF_IS_CLIP, &vcc->flags);
      clip_vcc->entry = NULL;
      clip_vcc->xoff = 0;
      clip_vcc->encap = 1;
      clip_vcc->last_use = jiffies;
      clip_vcc->idle_timeout = timeout * HZ;
      clip_vcc->old_push = vcc->push;
      clip_vcc->old_pop = vcc->pop;
      vcc->push = clip_push;
      vcc->pop = clip_pop;

      rq = &sk_atm(vcc)->sk_receive_queue;

      spin_lock_irqsave(&rq->lock, flags);
      if (skb_queue_empty(rq)) {
            skb = NULL;
      } else {
            /* NULL terminate the list.  */
            rq->prev->next = NULL;
            skb = rq->next;
      }
      rq->prev = rq->next = (struct sk_buff *)rq;
      rq->qlen = 0;
      spin_unlock_irqrestore(&rq->lock, flags);

      /* re-process everything received between connection setup and MKIP */
      while (skb) {
            struct sk_buff *next = skb->next;

            skb->next = skb->prev = NULL;
            if (!clip_devs) {
                  atm_return(vcc, skb->truesize);
                  kfree_skb(skb);
            } else {
                  unsigned int len = skb->len;

                  skb_get(skb);
                  clip_push(vcc, skb);
                  PRIV(skb->dev)->stats.rx_packets--;
                  PRIV(skb->dev)->stats.rx_bytes -= len;
                  kfree_skb(skb);
            }

            skb = next;
      }
      return 0;
}

static int clip_setentry(struct atm_vcc *vcc, __be32 ip)
{
      struct neighbour *neigh;
      struct atmarp_entry *entry;
      int error;
      struct clip_vcc *clip_vcc;
      struct flowi fl = { .nl_u = { .ip4_u = { .daddr = ip, .tos = 1}} };
      struct rtable *rt;

      if (vcc->push != clip_push) {
            printk(KERN_WARNING "clip_setentry: non-CLIP VCC\n");
            return -EBADF;
      }
      clip_vcc = CLIP_VCC(vcc);
      if (!ip) {
            if (!clip_vcc->entry) {
                  printk(KERN_ERR "hiding hidden ATMARP entry\n");
                  return 0;
            }
            pr_debug("setentry: remove\n");
            unlink_clip_vcc(clip_vcc);
            return 0;
      }
      error = ip_route_output_key(&rt, &fl);
      if (error)
            return error;
      neigh = __neigh_lookup(&clip_tbl, &ip, rt->u.dst.dev, 1);
      ip_rt_put(rt);
      if (!neigh)
            return -ENOMEM;
      entry = NEIGH2ENTRY(neigh);
      if (entry != clip_vcc->entry) {
            if (!clip_vcc->entry)
                  pr_debug("setentry: add\n");
            else {
                  pr_debug("setentry: update\n");
                  unlink_clip_vcc(clip_vcc);
            }
            link_vcc(clip_vcc, entry);
      }
      error = neigh_update(neigh, llc_oui, NUD_PERMANENT,
                       NEIGH_UPDATE_F_OVERRIDE | NEIGH_UPDATE_F_ADMIN);
      neigh_release(neigh);
      return error;
}

static void clip_setup(struct net_device *dev)
{
      dev->hard_start_xmit = clip_start_xmit;
      /* sg_xmit ... */
      dev->get_stats = clip_get_stats;
      dev->type = ARPHRD_ATM;
      dev->hard_header_len = RFC1483LLC_LEN;
      dev->mtu = RFC1626_MTU;
      dev->tx_queue_len = 100;      /* "normal" queue (packets) */
      /* When using a "real" qdisc, the qdisc determines the queue */
      /* length. tx_queue_len is only used for the default case, */
      /* without any more elaborate queuing. 100 is a reasonable */
      /* compromise between decent burst-tolerance and protection */
      /* against memory hogs. */
}

static int clip_create(int number)
{
      struct net_device *dev;
      struct clip_priv *clip_priv;
      int error;

      if (number != -1) {
            for (dev = clip_devs; dev; dev = PRIV(dev)->next)
                  if (PRIV(dev)->number == number)
                        return -EEXIST;
      } else {
            number = 0;
            for (dev = clip_devs; dev; dev = PRIV(dev)->next)
                  if (PRIV(dev)->number >= number)
                        number = PRIV(dev)->number + 1;
      }
      dev = alloc_netdev(sizeof(struct clip_priv), "", clip_setup);
      if (!dev)
            return -ENOMEM;
      clip_priv = PRIV(dev);
      sprintf(dev->name, "atm%d", number);
      spin_lock_init(&clip_priv->xoff_lock);
      clip_priv->number = number;
      error = register_netdev(dev);
      if (error) {
            free_netdev(dev);
            return error;
      }
      clip_priv->next = clip_devs;
      clip_devs = dev;
      pr_debug("registered (net:%s)\n", dev->name);
      return number;
}

static int clip_device_event(struct notifier_block *this, unsigned long event,
                       void *arg)
{
      struct net_device *dev = arg;

      if (dev->nd_net != &init_net)
            return NOTIFY_DONE;

      if (event == NETDEV_UNREGISTER) {
            neigh_ifdown(&clip_tbl, dev);
            return NOTIFY_DONE;
      }

      /* ignore non-CLIP devices */
      if (dev->type != ARPHRD_ATM || dev->hard_start_xmit != clip_start_xmit)
            return NOTIFY_DONE;

      switch (event) {
      case NETDEV_UP:
            pr_debug("clip_device_event NETDEV_UP\n");
            to_atmarpd(act_up, PRIV(dev)->number, 0);
            break;
      case NETDEV_GOING_DOWN:
            pr_debug("clip_device_event NETDEV_DOWN\n");
            to_atmarpd(act_down, PRIV(dev)->number, 0);
            break;
      case NETDEV_CHANGE:
      case NETDEV_CHANGEMTU:
            pr_debug("clip_device_event NETDEV_CHANGE*\n");
            to_atmarpd(act_change, PRIV(dev)->number, 0);
            break;
      }
      return NOTIFY_DONE;
}

static int clip_inet_event(struct notifier_block *this, unsigned long event,
                     void *ifa)
{
      struct in_device *in_dev;

      in_dev = ((struct in_ifaddr *)ifa)->ifa_dev;
      if (!in_dev || !in_dev->dev) {
            printk(KERN_WARNING "clip_inet_event: no device\n");
            return NOTIFY_DONE;
      }
      /*
       * Transitions are of the down-change-up type, so it's sufficient to
       * handle the change on up.
       */
      if (event != NETDEV_UP)
            return NOTIFY_DONE;
      return clip_device_event(this, NETDEV_CHANGE, in_dev->dev);
}


static struct notifier_block clip_dev_notifier = {
      .notifier_call = clip_device_event,
};



static struct notifier_block clip_inet_notifier = {
      .notifier_call = clip_inet_event,
};



static void atmarpd_close(struct atm_vcc *vcc)
{
      pr_debug("atmarpd_close\n");

      rtnl_lock();
      atmarpd = NULL;
      skb_queue_purge(&sk_atm(vcc)->sk_receive_queue);
      rtnl_unlock();

      pr_debug("(done)\n");
      module_put(THIS_MODULE);
}


static struct atmdev_ops atmarpd_dev_ops = {
      .close = atmarpd_close
};


static struct atm_dev atmarpd_dev = {
      .ops =                  &atmarpd_dev_ops,
      .type =                 "arpd",
      .number =         999,
      .lock =                 __SPIN_LOCK_UNLOCKED(atmarpd_dev.lock)
};


static int atm_init_atmarp(struct atm_vcc *vcc)
{
      rtnl_lock();
      if (atmarpd) {
            rtnl_unlock();
            return -EADDRINUSE;
      }

      mod_timer(&idle_timer, jiffies+CLIP_CHECK_INTERVAL*HZ);

      atmarpd = vcc;
      set_bit(ATM_VF_META,&vcc->flags);
      set_bit(ATM_VF_READY,&vcc->flags);
          /* allow replies and avoid getting closed if signaling dies */
      vcc->dev = &atmarpd_dev;
      vcc_insert_socket(sk_atm(vcc));
      vcc->push = NULL;
      vcc->pop = NULL; /* crash */
      vcc->push_oam = NULL; /* crash */
      rtnl_unlock();
      return 0;
}

static int clip_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
      struct atm_vcc *vcc = ATM_SD(sock);
      int err = 0;

      switch (cmd) {
      case SIOCMKCLIP:
      case ATMARPD_CTRL:
      case ATMARP_MKIP:
      case ATMARP_SETENTRY:
      case ATMARP_ENCAP:
            if (!capable(CAP_NET_ADMIN))
                  return -EPERM;
            break;
      default:
            return -ENOIOCTLCMD;
      }

      switch (cmd) {
      case SIOCMKCLIP:
            err = clip_create(arg);
            break;
      case ATMARPD_CTRL:
            err = atm_init_atmarp(vcc);
            if (!err) {
                  sock->state = SS_CONNECTED;
                  __module_get(THIS_MODULE);
            }
            break;
      case ATMARP_MKIP:
            err = clip_mkip(vcc, arg);
            break;
      case ATMARP_SETENTRY:
            err = clip_setentry(vcc, (__force __be32)arg);
            break;
      case ATMARP_ENCAP:
            err = clip_encap(vcc, arg);
            break;
      }
      return err;
}

static struct atm_ioctl clip_ioctl_ops = {
      .owner = THIS_MODULE,
      .ioctl = clip_ioctl,
};

#ifdef CONFIG_PROC_FS

static void svc_addr(struct seq_file *seq, struct sockaddr_atmsvc *addr)
{
      static int code[] = { 1, 2, 10, 6, 1, 0 };
      static int e164[] = { 1, 8, 4, 6, 1, 0 };

      if (*addr->sas_addr.pub) {
            seq_printf(seq, "%s", addr->sas_addr.pub);
            if (*addr->sas_addr.prv)
                  seq_putc(seq, '+');
      } else if (!*addr->sas_addr.prv) {
            seq_printf(seq, "%s", "(none)");
            return;
      }
      if (*addr->sas_addr.prv) {
            unsigned char *prv = addr->sas_addr.prv;
            int *fields;
            int i, j;

            fields = *prv == ATM_AFI_E164 ? e164 : code;
            for (i = 0; fields[i]; i++) {
                  for (j = fields[i]; j; j--)
                        seq_printf(seq, "%02X", *prv++);
                  if (fields[i + 1])
                        seq_putc(seq, '.');
            }
      }
}

/* This means the neighbour entry has no attached VCC objects. */
#define SEQ_NO_VCC_TOKEN      ((void *) 2)

static void atmarp_info(struct seq_file *seq, struct net_device *dev,
                  struct atmarp_entry *entry, struct clip_vcc *clip_vcc)
{
      unsigned long exp;
      char buf[17];
      int svc, llc, off;

      svc = ((clip_vcc == SEQ_NO_VCC_TOKEN) ||
             (sk_atm(clip_vcc->vcc)->sk_family == AF_ATMSVC));

      llc = ((clip_vcc == SEQ_NO_VCC_TOKEN) || clip_vcc->encap);

      if (clip_vcc == SEQ_NO_VCC_TOKEN)
            exp = entry->neigh->used;
      else
            exp = clip_vcc->last_use;

      exp = (jiffies - exp) / HZ;

      seq_printf(seq, "%-6s%-4s%-4s%5ld ",
               dev->name, svc ? "SVC" : "PVC", llc ? "LLC" : "NULL", exp);

      off = scnprintf(buf, sizeof(buf) - 1, "%d.%d.%d.%d",
                  NIPQUAD(entry->ip));
      while (off < 16)
            buf[off++] = ' ';
      buf[off] = '\0';
      seq_printf(seq, "%s", buf);

      if (clip_vcc == SEQ_NO_VCC_TOKEN) {
            if (time_before(jiffies, entry->expires))
                  seq_printf(seq, "(resolving)\n");
            else
                  seq_printf(seq, "(expired, ref %d)\n",
                           atomic_read(&entry->neigh->refcnt));
      } else if (!svc) {
            seq_printf(seq, "%d.%d.%d\n",
                     clip_vcc->vcc->dev->number,
                     clip_vcc->vcc->vpi, clip_vcc->vcc->vci);
      } else {
            svc_addr(seq, &clip_vcc->vcc->remote);
            seq_putc(seq, '\n');
      }
}

struct clip_seq_state {
      /* This member must be first. */
      struct neigh_seq_state ns;

      /* Local to clip specific iteration. */
      struct clip_vcc *vcc;
};

static struct clip_vcc *clip_seq_next_vcc(struct atmarp_entry *e,
                                struct clip_vcc *curr)
{
      if (!curr) {
            curr = e->vccs;
            if (!curr)
                  return SEQ_NO_VCC_TOKEN;
            return curr;
      }
      if (curr == SEQ_NO_VCC_TOKEN)
            return NULL;

      curr = curr->next;

      return curr;
}

static void *clip_seq_vcc_walk(struct clip_seq_state *state,
                         struct atmarp_entry *e, loff_t * pos)
{
      struct clip_vcc *vcc = state->vcc;

      vcc = clip_seq_next_vcc(e, vcc);
      if (vcc && pos != NULL) {
            while (*pos) {
                  vcc = clip_seq_next_vcc(e, vcc);
                  if (!vcc)
                        break;
                  --(*pos);
            }
      }
      state->vcc = vcc;

      return vcc;
}

static void *clip_seq_sub_iter(struct neigh_seq_state *_state,
                         struct neighbour *n, loff_t * pos)
{
      struct clip_seq_state *state = (struct clip_seq_state *)_state;

      return clip_seq_vcc_walk(state, NEIGH2ENTRY(n), pos);
}

static void *clip_seq_start(struct seq_file *seq, loff_t * pos)
{
      return neigh_seq_start(seq, pos, &clip_tbl, NEIGH_SEQ_NEIGH_ONLY);
}

static int clip_seq_show(struct seq_file *seq, void *v)
{
      static char atm_arp_banner[] =
          "IPitf TypeEncp Idle IP address      ATM address\n";

      if (v == SEQ_START_TOKEN) {
            seq_puts(seq, atm_arp_banner);
      } else {
            struct clip_seq_state *state = seq->private;
            struct neighbour *n = v;
            struct clip_vcc *vcc = state->vcc;

            atmarp_info(seq, n->dev, NEIGH2ENTRY(n), vcc);
      }
      return 0;
}

static const struct seq_operations arp_seq_ops = {
      .start      = clip_seq_start,
      .next = neigh_seq_next,
      .stop = neigh_seq_stop,
      .show = clip_seq_show,
};

static int arp_seq_open(struct inode *inode, struct file *file)
{
      struct clip_seq_state *state;
      struct seq_file *seq;
      int rc = -EAGAIN;

      state = kzalloc(sizeof(*state), GFP_KERNEL);
      if (!state) {
            rc = -ENOMEM;
            goto out_kfree;
      }
      state->ns.neigh_sub_iter = clip_seq_sub_iter;

      rc = seq_open(file, &arp_seq_ops);
      if (rc)
            goto out_kfree;

      seq = file->private_data;
      seq->private = state;
out:
      return rc;

out_kfree:
      kfree(state);
      goto out;
}

static const struct file_operations arp_seq_fops = {
      .open       = arp_seq_open,
      .read       = seq_read,
      .llseek           = seq_lseek,
      .release    = seq_release_private,
      .owner            = THIS_MODULE
};
#endif

static int __init atm_clip_init(void)
{
      neigh_table_init_no_netlink(&clip_tbl);

      clip_tbl_hook = &clip_tbl;
      register_atm_ioctl(&clip_ioctl_ops);
      register_netdevice_notifier(&clip_dev_notifier);
      register_inetaddr_notifier(&clip_inet_notifier);

      setup_timer(&idle_timer, idle_timer_check, 0);

#ifdef CONFIG_PROC_FS
      {
            struct proc_dir_entry *p;

            p = create_proc_entry("arp", S_IRUGO, atm_proc_root);
            if (p)
                  p->proc_fops = &arp_seq_fops;
      }
#endif

      return 0;
}

static void __exit atm_clip_exit(void)
{
      struct net_device *dev, *next;

      remove_proc_entry("arp", atm_proc_root);

      unregister_inetaddr_notifier(&clip_inet_notifier);
      unregister_netdevice_notifier(&clip_dev_notifier);

      deregister_atm_ioctl(&clip_ioctl_ops);

      /* First, stop the idle timer, so it stops banging
       * on the table.
       */
      del_timer_sync(&idle_timer);

      /* Next, purge the table, so that the device
       * unregister loop below does not hang due to
       * device references remaining in the table.
       */
      neigh_ifdown(&clip_tbl, NULL);

      dev = clip_devs;
      while (dev) {
            next = PRIV(dev)->next;
            unregister_netdev(dev);
            free_netdev(dev);
            dev = next;
      }

      /* Now it is safe to fully shutdown whole table. */
      neigh_table_clear(&clip_tbl);

      clip_tbl_hook = NULL;
}

module_init(atm_clip_init);
module_exit(atm_clip_exit);
MODULE_AUTHOR("Werner Almesberger");
MODULE_DESCRIPTION("Classical/IP over ATM interface");
MODULE_LICENSE("GPL");

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