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nfnetlink_queue.c

/*
 * This is a module which is used for queueing packets and communicating with
 * userspace via nfetlink.
 *
 * (C) 2005 by Harald Welte <laforge@netfilter.org>
 *
 * Based on the old ipv4-only ip_queue.c:
 * (C) 2000-2002 James Morris <jmorris@intercode.com.au>
 * (C) 2003-2005 Netfilter Core Team <coreteam@netfilter.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/notifier.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/proc_fs.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_queue.h>
#include <linux/list.h>
#include <net/sock.h>

#include <asm/atomic.h>

#ifdef CONFIG_BRIDGE_NETFILTER
#include "../bridge/br_private.h"
#endif

#define NFQNL_QMAX_DEFAULT 1024

#if 0
#define QDEBUG(x, args ...)   printk(KERN_DEBUG "%s(%d):%s():     " x,     \
                              __FILE__, __LINE__, __FUNCTION__,  \
                              ## args)
#else
#define QDEBUG(x, ...)
#endif

struct nfqnl_queue_entry {
      struct list_head list;
      struct nf_info *info;
      struct sk_buff *skb;
      unsigned int id;
};

struct nfqnl_instance {
      struct hlist_node hlist;            /* global list of queues */
      atomic_t use;

      int peer_pid;
      unsigned int queue_maxlen;
      unsigned int copy_range;
      unsigned int queue_total;
      unsigned int queue_dropped;
      unsigned int queue_user_dropped;

      atomic_t id_sequence;               /* 'sequence' of pkt ids */

      u_int16_t queue_num;                /* number of this queue */
      u_int8_t copy_mode;

      spinlock_t lock;

      struct list_head queue_list;        /* packets in queue */
};

typedef int (*nfqnl_cmpfn)(struct nfqnl_queue_entry *, unsigned long);

static DEFINE_RWLOCK(instances_lock);

#define INSTANCE_BUCKETS      16
static struct hlist_head instance_table[INSTANCE_BUCKETS];

static inline u_int8_t instance_hashfn(u_int16_t queue_num)
{
      return ((queue_num >> 8) | queue_num) % INSTANCE_BUCKETS;
}

static struct nfqnl_instance *
__instance_lookup(u_int16_t queue_num)
{
      struct hlist_head *head;
      struct hlist_node *pos;
      struct nfqnl_instance *inst;

      head = &instance_table[instance_hashfn(queue_num)];
      hlist_for_each_entry(inst, pos, head, hlist) {
            if (inst->queue_num == queue_num)
                  return inst;
      }
      return NULL;
}

static struct nfqnl_instance *
instance_lookup_get(u_int16_t queue_num)
{
      struct nfqnl_instance *inst;

      read_lock_bh(&instances_lock);
      inst = __instance_lookup(queue_num);
      if (inst)
            atomic_inc(&inst->use);
      read_unlock_bh(&instances_lock);

      return inst;
}

static void
instance_put(struct nfqnl_instance *inst)
{
      if (inst && atomic_dec_and_test(&inst->use)) {
            QDEBUG("kfree(inst=%p)\n", inst);
            kfree(inst);
      }
}

static struct nfqnl_instance *
instance_create(u_int16_t queue_num, int pid)
{
      struct nfqnl_instance *inst;

      QDEBUG("entering for queue_num=%u, pid=%d\n", queue_num, pid);

      write_lock_bh(&instances_lock);
      if (__instance_lookup(queue_num)) {
            inst = NULL;
            QDEBUG("aborting, instance already exists\n");
            goto out_unlock;
      }

      inst = kzalloc(sizeof(*inst), GFP_ATOMIC);
      if (!inst)
            goto out_unlock;

      inst->queue_num = queue_num;
      inst->peer_pid = pid;
      inst->queue_maxlen = NFQNL_QMAX_DEFAULT;
      inst->copy_range = 0xfffff;
      inst->copy_mode = NFQNL_COPY_NONE;
      atomic_set(&inst->id_sequence, 0);
      /* needs to be two, since we _put() after creation */
      atomic_set(&inst->use, 2);
      spin_lock_init(&inst->lock);
      INIT_LIST_HEAD(&inst->queue_list);

      if (!try_module_get(THIS_MODULE))
            goto out_free;

      hlist_add_head(&inst->hlist,
                   &instance_table[instance_hashfn(queue_num)]);

      write_unlock_bh(&instances_lock);

      QDEBUG("successfully created new instance\n");

      return inst;

out_free:
      kfree(inst);
out_unlock:
      write_unlock_bh(&instances_lock);
      return NULL;
}

static void nfqnl_flush(struct nfqnl_instance *queue, int verdict);

static void
_instance_destroy2(struct nfqnl_instance *inst, int lock)
{
      /* first pull it out of the global list */
      if (lock)
            write_lock_bh(&instances_lock);

      QDEBUG("removing instance %p (queuenum=%u) from hash\n",
            inst, inst->queue_num);
      hlist_del(&inst->hlist);

      if (lock)
            write_unlock_bh(&instances_lock);

      /* then flush all pending skbs from the queue */
      nfqnl_flush(inst, NF_DROP);

      /* and finally put the refcount */
      instance_put(inst);

      module_put(THIS_MODULE);
}

static inline void
__instance_destroy(struct nfqnl_instance *inst)
{
      _instance_destroy2(inst, 0);
}

static inline void
instance_destroy(struct nfqnl_instance *inst)
{
      _instance_destroy2(inst, 1);
}



static void
issue_verdict(struct nfqnl_queue_entry *entry, int verdict)
{
      QDEBUG("entering for entry %p, verdict %u\n", entry, verdict);

      /* TCP input path (and probably other bits) assume to be called
       * from softirq context, not from syscall, like issue_verdict is
       * called.  TCP input path deadlocks with locks taken from timer
       * softirq, e.g.  We therefore emulate this by local_bh_disable() */

      local_bh_disable();
      nf_reinject(entry->skb, entry->info, verdict);
      local_bh_enable();

      kfree(entry);
}

static inline void
__enqueue_entry(struct nfqnl_instance *queue,
                  struct nfqnl_queue_entry *entry)
{
       list_add(&entry->list, &queue->queue_list);
       queue->queue_total++;
}

/*
 * Find and return a queued entry matched by cmpfn, or return the last
 * entry if cmpfn is NULL.
 */
static inline struct nfqnl_queue_entry *
__find_entry(struct nfqnl_instance *queue, nfqnl_cmpfn cmpfn,
               unsigned long data)
{
      struct list_head *p;

      list_for_each_prev(p, &queue->queue_list) {
            struct nfqnl_queue_entry *entry = (struct nfqnl_queue_entry *)p;

            if (!cmpfn || cmpfn(entry, data))
                  return entry;
      }
      return NULL;
}

static inline void
__dequeue_entry(struct nfqnl_instance *q, struct nfqnl_queue_entry *entry)
{
      list_del(&entry->list);
      q->queue_total--;
}

static inline struct nfqnl_queue_entry *
__find_dequeue_entry(struct nfqnl_instance *queue,
                 nfqnl_cmpfn cmpfn, unsigned long data)
{
      struct nfqnl_queue_entry *entry;

      entry = __find_entry(queue, cmpfn, data);
      if (entry == NULL)
            return NULL;

      __dequeue_entry(queue, entry);
      return entry;
}


static inline void
__nfqnl_flush(struct nfqnl_instance *queue, int verdict)
{
      struct nfqnl_queue_entry *entry;

      while ((entry = __find_dequeue_entry(queue, NULL, 0)))
            issue_verdict(entry, verdict);
}

static inline int
__nfqnl_set_mode(struct nfqnl_instance *queue,
             unsigned char mode, unsigned int range)
{
      int status = 0;

      switch (mode) {
      case NFQNL_COPY_NONE:
      case NFQNL_COPY_META:
            queue->copy_mode = mode;
            queue->copy_range = 0;
            break;

      case NFQNL_COPY_PACKET:
            queue->copy_mode = mode;
            /* we're using struct nlattr which has 16bit nla_len */
            if (range > 0xffff)
                  queue->copy_range = 0xffff;
            else
                  queue->copy_range = range;
            break;

      default:
            status = -EINVAL;

      }
      return status;
}

static struct nfqnl_queue_entry *
find_dequeue_entry(struct nfqnl_instance *queue,
                   nfqnl_cmpfn cmpfn, unsigned long data)
{
      struct nfqnl_queue_entry *entry;

      spin_lock_bh(&queue->lock);
      entry = __find_dequeue_entry(queue, cmpfn, data);
      spin_unlock_bh(&queue->lock);

      return entry;
}

static void
nfqnl_flush(struct nfqnl_instance *queue, int verdict)
{
      spin_lock_bh(&queue->lock);
      __nfqnl_flush(queue, verdict);
      spin_unlock_bh(&queue->lock);
}

static struct sk_buff *
nfqnl_build_packet_message(struct nfqnl_instance *queue,
                     struct nfqnl_queue_entry *entry, int *errp)
{
      sk_buff_data_t old_tail;
      size_t size;
      size_t data_len = 0;
      struct sk_buff *skb;
      struct nfqnl_msg_packet_hdr pmsg;
      struct nlmsghdr *nlh;
      struct nfgenmsg *nfmsg;
      struct nf_info *entinf = entry->info;
      struct sk_buff *entskb = entry->skb;
      struct net_device *indev;
      struct net_device *outdev;
      __be32 tmp_uint;

      QDEBUG("entered\n");

      size =    NLMSG_ALIGN(sizeof(struct nfgenmsg))
            + nla_total_size(sizeof(struct nfqnl_msg_packet_hdr))
            + nla_total_size(sizeof(u_int32_t)) /* ifindex */
            + nla_total_size(sizeof(u_int32_t)) /* ifindex */
#ifdef CONFIG_BRIDGE_NETFILTER
            + nla_total_size(sizeof(u_int32_t)) /* ifindex */
            + nla_total_size(sizeof(u_int32_t)) /* ifindex */
#endif
            + nla_total_size(sizeof(u_int32_t)) /* mark */
            + nla_total_size(sizeof(struct nfqnl_msg_packet_hw))
            + nla_total_size(sizeof(struct nfqnl_msg_packet_timestamp));

      outdev = entinf->outdev;

      spin_lock_bh(&queue->lock);

      switch (queue->copy_mode) {
      case NFQNL_COPY_META:
      case NFQNL_COPY_NONE:
            data_len = 0;
            break;

      case NFQNL_COPY_PACKET:
            if ((entskb->ip_summed == CHECKSUM_PARTIAL ||
                 entskb->ip_summed == CHECKSUM_COMPLETE) &&
                (*errp = skb_checksum_help(entskb))) {
                  spin_unlock_bh(&queue->lock);
                  return NULL;
            }
            if (queue->copy_range == 0
                || queue->copy_range > entskb->len)
                  data_len = entskb->len;
            else
                  data_len = queue->copy_range;

            size += nla_total_size(data_len);
            break;

      default:
            *errp = -EINVAL;
            spin_unlock_bh(&queue->lock);
            return NULL;
      }

      spin_unlock_bh(&queue->lock);

      skb = alloc_skb(size, GFP_ATOMIC);
      if (!skb)
            goto nlmsg_failure;

      old_tail = skb->tail;
      nlh = NLMSG_PUT(skb, 0, 0,
                  NFNL_SUBSYS_QUEUE << 8 | NFQNL_MSG_PACKET,
                  sizeof(struct nfgenmsg));
      nfmsg = NLMSG_DATA(nlh);
      nfmsg->nfgen_family = entinf->pf;
      nfmsg->version = NFNETLINK_V0;
      nfmsg->res_id = htons(queue->queue_num);

      pmsg.packet_id          = htonl(entry->id);
      pmsg.hw_protocol  = entskb->protocol;
      pmsg.hook         = entinf->hook;

      NLA_PUT(skb, NFQA_PACKET_HDR, sizeof(pmsg), &pmsg);

      indev = entinf->indev;
      if (indev) {
            tmp_uint = htonl(indev->ifindex);
#ifndef CONFIG_BRIDGE_NETFILTER
            NLA_PUT(skb, NFQA_IFINDEX_INDEV, sizeof(tmp_uint), &tmp_uint);
#else
            if (entinf->pf == PF_BRIDGE) {
                  /* Case 1: indev is physical input device, we need to
                   * look for bridge group (when called from
                   * netfilter_bridge) */
                  NLA_PUT(skb, NFQA_IFINDEX_PHYSINDEV, sizeof(tmp_uint),
                        &tmp_uint);
                  /* this is the bridge group "brX" */
                  tmp_uint = htonl(indev->br_port->br->dev->ifindex);
                  NLA_PUT(skb, NFQA_IFINDEX_INDEV, sizeof(tmp_uint),
                        &tmp_uint);
            } else {
                  /* Case 2: indev is bridge group, we need to look for
                   * physical device (when called from ipv4) */
                  NLA_PUT(skb, NFQA_IFINDEX_INDEV, sizeof(tmp_uint),
                        &tmp_uint);
                  if (entskb->nf_bridge
                      && entskb->nf_bridge->physindev) {
                        tmp_uint = htonl(entskb->nf_bridge->physindev->ifindex);
                        NLA_PUT(skb, NFQA_IFINDEX_PHYSINDEV,
                              sizeof(tmp_uint), &tmp_uint);
                  }
            }
#endif
      }

      if (outdev) {
            tmp_uint = htonl(outdev->ifindex);
#ifndef CONFIG_BRIDGE_NETFILTER
            NLA_PUT(skb, NFQA_IFINDEX_OUTDEV, sizeof(tmp_uint), &tmp_uint);
#else
            if (entinf->pf == PF_BRIDGE) {
                  /* Case 1: outdev is physical output device, we need to
                   * look for bridge group (when called from
                   * netfilter_bridge) */
                  NLA_PUT(skb, NFQA_IFINDEX_PHYSOUTDEV, sizeof(tmp_uint),
                        &tmp_uint);
                  /* this is the bridge group "brX" */
                  tmp_uint = htonl(outdev->br_port->br->dev->ifindex);
                  NLA_PUT(skb, NFQA_IFINDEX_OUTDEV, sizeof(tmp_uint),
                        &tmp_uint);
            } else {
                  /* Case 2: outdev is bridge group, we need to look for
                   * physical output device (when called from ipv4) */
                  NLA_PUT(skb, NFQA_IFINDEX_OUTDEV, sizeof(tmp_uint),
                        &tmp_uint);
                  if (entskb->nf_bridge
                      && entskb->nf_bridge->physoutdev) {
                        tmp_uint = htonl(entskb->nf_bridge->physoutdev->ifindex);
                        NLA_PUT(skb, NFQA_IFINDEX_PHYSOUTDEV,
                              sizeof(tmp_uint), &tmp_uint);
                  }
            }
#endif
      }

      if (entskb->mark) {
            tmp_uint = htonl(entskb->mark);
            NLA_PUT(skb, NFQA_MARK, sizeof(u_int32_t), &tmp_uint);
      }

      if (indev && entskb->dev) {
            struct nfqnl_msg_packet_hw phw;
            int len = dev_parse_header(entskb, phw.hw_addr);
            if (len) {
                  phw.hw_addrlen = htons(len);
                  NLA_PUT(skb, NFQA_HWADDR, sizeof(phw), &phw);
            }
      }

      if (entskb->tstamp.tv64) {
            struct nfqnl_msg_packet_timestamp ts;
            struct timeval tv = ktime_to_timeval(entskb->tstamp);
            ts.sec = cpu_to_be64(tv.tv_sec);
            ts.usec = cpu_to_be64(tv.tv_usec);

            NLA_PUT(skb, NFQA_TIMESTAMP, sizeof(ts), &ts);
      }

      if (data_len) {
            struct nlattr *nla;
            int size = nla_attr_size(data_len);

            if (skb_tailroom(skb) < nla_total_size(data_len)) {
                  printk(KERN_WARNING "nf_queue: no tailroom!\n");
                  goto nlmsg_failure;
            }

            nla = (struct nlattr *)skb_put(skb, nla_total_size(data_len));
            nla->nla_type = NFQA_PAYLOAD;
            nla->nla_len = size;

            if (skb_copy_bits(entskb, 0, nla_data(nla), data_len))
                  BUG();
      }

      nlh->nlmsg_len = skb->tail - old_tail;
      return skb;

nlmsg_failure:
nla_put_failure:
      if (skb)
            kfree_skb(skb);
      *errp = -EINVAL;
      if (net_ratelimit())
            printk(KERN_ERR "nf_queue: error creating packet message\n");
      return NULL;
}

static int
nfqnl_enqueue_packet(struct sk_buff *skb, struct nf_info *info,
                 unsigned int queuenum, void *data)
{
      int status = -EINVAL;
      struct sk_buff *nskb;
      struct nfqnl_instance *queue;
      struct nfqnl_queue_entry *entry;

      QDEBUG("entered\n");

      queue = instance_lookup_get(queuenum);
      if (!queue) {
            QDEBUG("no queue instance matching\n");
            return -EINVAL;
      }

      if (queue->copy_mode == NFQNL_COPY_NONE) {
            QDEBUG("mode COPY_NONE, aborting\n");
            status = -EAGAIN;
            goto err_out_put;
      }

      entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
      if (entry == NULL) {
            if (net_ratelimit())
                  printk(KERN_ERR
                        "nf_queue: OOM in nfqnl_enqueue_packet()\n");
            status = -ENOMEM;
            goto err_out_put;
      }

      entry->info = info;
      entry->skb = skb;
      entry->id = atomic_inc_return(&queue->id_sequence);

      nskb = nfqnl_build_packet_message(queue, entry, &status);
      if (nskb == NULL)
            goto err_out_free;

      spin_lock_bh(&queue->lock);

      if (!queue->peer_pid)
            goto err_out_free_nskb;

      if (queue->queue_total >= queue->queue_maxlen) {
            queue->queue_dropped++;
            status = -ENOSPC;
            if (net_ratelimit())
                    printk(KERN_WARNING "nf_queue: full at %d entries, "
                         "dropping packets(s). Dropped: %d\n",
                         queue->queue_total, queue->queue_dropped);
            goto err_out_free_nskb;
      }

      /* nfnetlink_unicast will either free the nskb or add it to a socket */
      status = nfnetlink_unicast(nskb, queue->peer_pid, MSG_DONTWAIT);
      if (status < 0) {
            queue->queue_user_dropped++;
            goto err_out_unlock;
      }

      __enqueue_entry(queue, entry);

      spin_unlock_bh(&queue->lock);
      instance_put(queue);
      return status;

err_out_free_nskb:
      kfree_skb(nskb);

err_out_unlock:
      spin_unlock_bh(&queue->lock);

err_out_free:
      kfree(entry);
err_out_put:
      instance_put(queue);
      return status;
}

static int
nfqnl_mangle(void *data, int data_len, struct nfqnl_queue_entry *e)
{
      int diff;
      int err;

      diff = data_len - e->skb->len;
      if (diff < 0) {
            if (pskb_trim(e->skb, data_len))
                  return -ENOMEM;
      } else if (diff > 0) {
            if (data_len > 0xFFFF)
                  return -EINVAL;
            if (diff > skb_tailroom(e->skb)) {
                  err = pskb_expand_head(e->skb, 0,
                                     diff - skb_tailroom(e->skb),
                                     GFP_ATOMIC);
                  if (err) {
                        printk(KERN_WARNING "nf_queue: OOM "
                              "in mangle, dropping packet\n");
                        return err;
                  }
            }
            skb_put(e->skb, diff);
      }
      if (!skb_make_writable(e->skb, data_len))
            return -ENOMEM;
      skb_copy_to_linear_data(e->skb, data, data_len);
      e->skb->ip_summed = CHECKSUM_NONE;
      return 0;
}

static inline int
id_cmp(struct nfqnl_queue_entry *e, unsigned long id)
{
      return (id == e->id);
}

static int
nfqnl_set_mode(struct nfqnl_instance *queue,
             unsigned char mode, unsigned int range)
{
      int status;

      spin_lock_bh(&queue->lock);
      status = __nfqnl_set_mode(queue, mode, range);
      spin_unlock_bh(&queue->lock);

      return status;
}

static int
dev_cmp(struct nfqnl_queue_entry *entry, unsigned long ifindex)
{
      struct nf_info *entinf = entry->info;

      if (entinf->indev)
            if (entinf->indev->ifindex == ifindex)
                  return 1;
      if (entinf->outdev)
            if (entinf->outdev->ifindex == ifindex)
                  return 1;
#ifdef CONFIG_BRIDGE_NETFILTER
      if (entry->skb->nf_bridge) {
            if (entry->skb->nf_bridge->physindev &&
                entry->skb->nf_bridge->physindev->ifindex == ifindex)
                  return 1;
            if (entry->skb->nf_bridge->physoutdev &&
                entry->skb->nf_bridge->physoutdev->ifindex == ifindex)
                  return 1;
      }
#endif
      return 0;
}

/* drop all packets with either indev or outdev == ifindex from all queue
 * instances */
static void
nfqnl_dev_drop(int ifindex)
{
      int i;

      QDEBUG("entering for ifindex %u\n", ifindex);

      /* this only looks like we have to hold the readlock for a way too long
       * time, issue_verdict(),  nf_reinject(), ... - but we always only
       * issue NF_DROP, which is processed directly in nf_reinject() */
      read_lock_bh(&instances_lock);

      for  (i = 0; i < INSTANCE_BUCKETS; i++) {
            struct hlist_node *tmp;
            struct nfqnl_instance *inst;
            struct hlist_head *head = &instance_table[i];

            hlist_for_each_entry(inst, tmp, head, hlist) {
                  struct nfqnl_queue_entry *entry;
                  while ((entry = find_dequeue_entry(inst, dev_cmp,
                                             ifindex)) != NULL)
                        issue_verdict(entry, NF_DROP);
            }
      }

      read_unlock_bh(&instances_lock);
}

#define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)

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

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

      /* Drop any packets associated with the downed device */
      if (event == NETDEV_DOWN)
            nfqnl_dev_drop(dev->ifindex);
      return NOTIFY_DONE;
}

static struct notifier_block nfqnl_dev_notifier = {
      .notifier_call    = nfqnl_rcv_dev_event,
};

static int
nfqnl_rcv_nl_event(struct notifier_block *this,
               unsigned long event, void *ptr)
{
      struct netlink_notify *n = ptr;

      if (event == NETLINK_URELEASE &&
          n->protocol == NETLINK_NETFILTER && n->pid) {
            int i;

            /* destroy all instances for this pid */
            write_lock_bh(&instances_lock);
            for  (i = 0; i < INSTANCE_BUCKETS; i++) {
                  struct hlist_node *tmp, *t2;
                  struct nfqnl_instance *inst;
                  struct hlist_head *head = &instance_table[i];

                  hlist_for_each_entry_safe(inst, tmp, t2, head, hlist) {
                        if ((n->net == &init_net) &&
                            (n->pid == inst->peer_pid))
                              __instance_destroy(inst);
                  }
            }
            write_unlock_bh(&instances_lock);
      }
      return NOTIFY_DONE;
}

static struct notifier_block nfqnl_rtnl_notifier = {
      .notifier_call    = nfqnl_rcv_nl_event,
};

static const struct nla_policy nfqa_verdict_policy[NFQA_MAX+1] = {
      [NFQA_VERDICT_HDR]      = { .len = sizeof(struct nfqnl_msg_verdict_hdr) },
      [NFQA_MARK]       = { .type = NLA_U32 },
      [NFQA_PAYLOAD]          = { .type = NLA_UNSPEC },
};

static int
nfqnl_recv_verdict(struct sock *ctnl, struct sk_buff *skb,
               struct nlmsghdr *nlh, struct nlattr *nfqa[])
{
      struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
      u_int16_t queue_num = ntohs(nfmsg->res_id);

      struct nfqnl_msg_verdict_hdr *vhdr;
      struct nfqnl_instance *queue;
      unsigned int verdict;
      struct nfqnl_queue_entry *entry;
      int err;

      queue = instance_lookup_get(queue_num);
      if (!queue)
            return -ENODEV;

      if (queue->peer_pid != NETLINK_CB(skb).pid) {
            err = -EPERM;
            goto err_out_put;
      }

      if (!nfqa[NFQA_VERDICT_HDR]) {
            err = -EINVAL;
            goto err_out_put;
      }

      vhdr = nla_data(nfqa[NFQA_VERDICT_HDR]);
      verdict = ntohl(vhdr->verdict);

      if ((verdict & NF_VERDICT_MASK) > NF_MAX_VERDICT) {
            err = -EINVAL;
            goto err_out_put;
      }

      entry = find_dequeue_entry(queue, id_cmp, ntohl(vhdr->id));
      if (entry == NULL) {
            err = -ENOENT;
            goto err_out_put;
      }

      if (nfqa[NFQA_PAYLOAD]) {
            if (nfqnl_mangle(nla_data(nfqa[NFQA_PAYLOAD]),
                         nla_len(nfqa[NFQA_PAYLOAD]), entry) < 0)
                  verdict = NF_DROP;
      }

      if (nfqa[NFQA_MARK])
            entry->skb->mark = ntohl(*(__be32 *)
                               nla_data(nfqa[NFQA_MARK]));

      issue_verdict(entry, verdict);
      instance_put(queue);
      return 0;

err_out_put:
      instance_put(queue);
      return err;
}

static int
nfqnl_recv_unsupp(struct sock *ctnl, struct sk_buff *skb,
              struct nlmsghdr *nlh, struct nlattr *nfqa[])
{
      return -ENOTSUPP;
}

static const struct nla_policy nfqa_cfg_policy[NFQA_CFG_MAX+1] = {
      [NFQA_CFG_CMD]          = { .len = sizeof(struct nfqnl_msg_config_cmd) },
      [NFQA_CFG_PARAMS] = { .len = sizeof(struct nfqnl_msg_config_params) },
};

static struct nf_queue_handler nfqh = {
      .name       = "nf_queue",
      .outfn      = &nfqnl_enqueue_packet,
};

static int
nfqnl_recv_config(struct sock *ctnl, struct sk_buff *skb,
              struct nlmsghdr *nlh, struct nlattr *nfqa[])
{
      struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
      u_int16_t queue_num = ntohs(nfmsg->res_id);
      struct nfqnl_instance *queue;
      int ret = 0;

      QDEBUG("entering for msg %u\n", NFNL_MSG_TYPE(nlh->nlmsg_type));

      queue = instance_lookup_get(queue_num);
      if (nfqa[NFQA_CFG_CMD]) {
            struct nfqnl_msg_config_cmd *cmd;
            cmd = nla_data(nfqa[NFQA_CFG_CMD]);
            QDEBUG("found CFG_CMD\n");

            switch (cmd->command) {
            case NFQNL_CFG_CMD_BIND:
                  if (queue)
                        return -EBUSY;

                  queue = instance_create(queue_num, NETLINK_CB(skb).pid);
                  if (!queue)
                        return -EINVAL;
                  break;
            case NFQNL_CFG_CMD_UNBIND:
                  if (!queue)
                        return -ENODEV;

                  if (queue->peer_pid != NETLINK_CB(skb).pid) {
                        ret = -EPERM;
                        goto out_put;
                  }

                  instance_destroy(queue);
                  break;
            case NFQNL_CFG_CMD_PF_BIND:
                  QDEBUG("registering queue handler for pf=%u\n",
                        ntohs(cmd->pf));
                  ret = nf_register_queue_handler(ntohs(cmd->pf), &nfqh);
                  break;
            case NFQNL_CFG_CMD_PF_UNBIND:
                  QDEBUG("unregistering queue handler for pf=%u\n",
                        ntohs(cmd->pf));
                  ret = nf_unregister_queue_handler(ntohs(cmd->pf), &nfqh);
                  break;
            default:
                  ret = -EINVAL;
                  break;
            }
      } else {
            if (!queue) {
                  QDEBUG("no config command, and no instance ENOENT\n");
                  ret = -ENOENT;
                  goto out_put;
            }

            if (queue->peer_pid != NETLINK_CB(skb).pid) {
                  QDEBUG("no config command, and wrong pid\n");
                  ret = -EPERM;
                  goto out_put;
            }
      }

      if (nfqa[NFQA_CFG_PARAMS]) {
            struct nfqnl_msg_config_params *params;

            if (!queue) {
                  ret = -ENOENT;
                  goto out_put;
            }
            params = nla_data(nfqa[NFQA_CFG_PARAMS]);
            nfqnl_set_mode(queue, params->copy_mode,
                        ntohl(params->copy_range));
      }

      if (nfqa[NFQA_CFG_QUEUE_MAXLEN]) {
            __be32 *queue_maxlen;
            queue_maxlen = nla_data(nfqa[NFQA_CFG_QUEUE_MAXLEN]);
            spin_lock_bh(&queue->lock);
            queue->queue_maxlen = ntohl(*queue_maxlen);
            spin_unlock_bh(&queue->lock);
      }

out_put:
      instance_put(queue);
      return ret;
}

static const struct nfnl_callback nfqnl_cb[NFQNL_MSG_MAX] = {
      [NFQNL_MSG_PACKET]      = { .call = nfqnl_recv_unsupp,
                            .attr_count = NFQA_MAX, },
      [NFQNL_MSG_VERDICT]     = { .call = nfqnl_recv_verdict,
                            .attr_count = NFQA_MAX,
                            .policy = nfqa_verdict_policy },
      [NFQNL_MSG_CONFIG]      = { .call = nfqnl_recv_config,
                            .attr_count = NFQA_CFG_MAX,
                            .policy = nfqa_cfg_policy },
};

static const struct nfnetlink_subsystem nfqnl_subsys = {
      .name       = "nf_queue",
      .subsys_id  = NFNL_SUBSYS_QUEUE,
      .cb_count   = NFQNL_MSG_MAX,
      .cb         = nfqnl_cb,
};

#ifdef CONFIG_PROC_FS
struct iter_state {
      unsigned int bucket;
};

static struct hlist_node *get_first(struct seq_file *seq)
{
      struct iter_state *st = seq->private;

      if (!st)
            return NULL;

      for (st->bucket = 0; st->bucket < INSTANCE_BUCKETS; st->bucket++) {
            if (!hlist_empty(&instance_table[st->bucket]))
                  return instance_table[st->bucket].first;
      }
      return NULL;
}

static struct hlist_node *get_next(struct seq_file *seq, struct hlist_node *h)
{
      struct iter_state *st = seq->private;

      h = h->next;
      while (!h) {
            if (++st->bucket >= INSTANCE_BUCKETS)
                  return NULL;

            h = instance_table[st->bucket].first;
      }
      return h;
}

static struct hlist_node *get_idx(struct seq_file *seq, loff_t pos)
{
      struct hlist_node *head;
      head = get_first(seq);

      if (head)
            while (pos && (head = get_next(seq, head)))
                  pos--;
      return pos ? NULL : head;
}

static void *seq_start(struct seq_file *seq, loff_t *pos)
{
      read_lock_bh(&instances_lock);
      return get_idx(seq, *pos);
}

static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
{
      (*pos)++;
      return get_next(s, v);
}

static void seq_stop(struct seq_file *s, void *v)
{
      read_unlock_bh(&instances_lock);
}

static int seq_show(struct seq_file *s, void *v)
{
      const struct nfqnl_instance *inst = v;

      return seq_printf(s, "%5d %6d %5d %1d %5d %5d %5d %8d %2d\n",
                    inst->queue_num,
                    inst->peer_pid, inst->queue_total,
                    inst->copy_mode, inst->copy_range,
                    inst->queue_dropped, inst->queue_user_dropped,
                    atomic_read(&inst->id_sequence),
                    atomic_read(&inst->use));
}

static const struct seq_operations nfqnl_seq_ops = {
      .start      = seq_start,
      .next = seq_next,
      .stop = seq_stop,
      .show = seq_show,
};

static int nfqnl_open(struct inode *inode, struct file *file)
{
      return seq_open_private(file, &nfqnl_seq_ops,
                  sizeof(struct iter_state));
}

static const struct file_operations nfqnl_file_ops = {
      .owner       = THIS_MODULE,
      .open  = nfqnl_open,
      .read  = seq_read,
      .llseek      = seq_lseek,
      .release = seq_release_private,
};

#endif /* PROC_FS */

static int __init nfnetlink_queue_init(void)
{
      int i, status = -ENOMEM;
#ifdef CONFIG_PROC_FS
      struct proc_dir_entry *proc_nfqueue;
#endif

      for (i = 0; i < INSTANCE_BUCKETS; i++)
            INIT_HLIST_HEAD(&instance_table[i]);

      netlink_register_notifier(&nfqnl_rtnl_notifier);
      status = nfnetlink_subsys_register(&nfqnl_subsys);
      if (status < 0) {
            printk(KERN_ERR "nf_queue: failed to create netlink socket\n");
            goto cleanup_netlink_notifier;
      }

#ifdef CONFIG_PROC_FS
      proc_nfqueue = create_proc_entry("nfnetlink_queue", 0440,
                               proc_net_netfilter);
      if (!proc_nfqueue)
            goto cleanup_subsys;
      proc_nfqueue->proc_fops = &nfqnl_file_ops;
#endif

      register_netdevice_notifier(&nfqnl_dev_notifier);
      return status;

#ifdef CONFIG_PROC_FS
cleanup_subsys:
      nfnetlink_subsys_unregister(&nfqnl_subsys);
#endif
cleanup_netlink_notifier:
      netlink_unregister_notifier(&nfqnl_rtnl_notifier);
      return status;
}

static void __exit nfnetlink_queue_fini(void)
{
      nf_unregister_queue_handlers(&nfqh);
      unregister_netdevice_notifier(&nfqnl_dev_notifier);
#ifdef CONFIG_PROC_FS
      remove_proc_entry("nfnetlink_queue", proc_net_netfilter);
#endif
      nfnetlink_subsys_unregister(&nfqnl_subsys);
      netlink_unregister_notifier(&nfqnl_rtnl_notifier);
}

MODULE_DESCRIPTION("netfilter packet queue handler");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_QUEUE);

module_init(nfnetlink_queue_init);
module_exit(nfnetlink_queue_fini);

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