text: /*
   * This is a module which is used for queueing packets and communicating with
   * userspace via nfnetlink.
   *
   * (C) 2005 by Harald Welte <laforge@netfilter.org>
   * (C) 2007 by Patrick McHardy <kaber@trash.net>
   *
   * 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/slab.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 <net/netfilter/nf_queue.h>
  
  #include <linux/atomic.h>
  
  #ifdef CONFIG_BRIDGE_NETFILTER
  #include "../bridge/br_private.h"
  #endif
  
  #define NFQNL_QMAX_DEFAULT 1024
  
  struct nfqnl_instance {
  	struct hlist_node hlist;		/* global list of queues */
  	struct rcu_head rcu;
  
  	int peer_pid;
  	unsigned int queue_maxlen;
  	unsigned int copy_range;
  	unsigned int queue_dropped;
  	unsigned int queue_user_dropped;
  
  
  	u_int16_t queue_num;			/* number of this queue */
  	u_int8_t copy_mode;
  /*
   * Following fields are dirtied for each queued packet,
   * keep them in same cache line if possible.
   */
  	spinlock_t	lock;
  	unsigned int	queue_total;
  	unsigned int	id_sequence;		/* 'sequence' of pkt ids */
  	struct list_head queue_list;		/* packets in queue */
  };
  
  typedef int (*nfqnl_cmpfn)(struct nf_queue_entry *, unsigned long);
  
  static DEFINE_SPINLOCK(instances_lock);
  
  #define INSTANCE_BUCKETS	16
  static struct hlist_head instance_table[INSTANCE_BUCKETS] __read_mostly;
  
  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_rcu(inst, pos, head, hlist) {
  		if (inst->queue_num == queue_num)
  			return inst;
  	}
  	return NULL;
  }
  
  static struct nfqnl_instance *
  instance_create(u_int16_t queue_num, int pid)
  {
  	struct nfqnl_instance *inst;
  	unsigned int h;
  	int err;
  
  	spin_lock(&instances_lock);
  	if (instance_lookup(queue_num)) {
  		err = -EEXIST;
  		goto out_unlock;
  	}
  
  	inst = kzalloc(sizeof(*inst), GFP_ATOMIC);
  	if (!inst) {
  		err = -ENOMEM;
  		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;
  	spin_lock_init(&inst->lock);
  	INIT_LIST_HEAD(&inst->queue_list);
  
  	if (!try_module_get(THIS_MODULE)) {
  		err = -EAGAIN;
  		goto out_free;
  	}
  
  	h = instance_hashfn(queue_num);
  	hlist_add_head_rcu(&inst->hlist, &instance_table[h]);
  
  	spin_unlock(&instances_lock);
  
  	return inst;
  
  out_free:
  	kfree(inst);
  out_unlock:
  	spin_unlock(&instances_lock);
  	return ERR_PTR(err);
  }
  
  static void nfqnl_flush(struct nfqnl_instance *queue, nfqnl_cmpfn cmpfn,
  			unsigned long data);
  
  static void
  instance_destroy_rcu(struct rcu_head *head)
  {
  	struct nfqnl_instance *inst = container_of(head, struct nfqnl_instance,
  						   rcu);
  
  	nfqnl_flush(inst, NULL, 0);
  	kfree(inst);
  	module_put(THIS_MODULE);
  }
  
  static void
  __instance_destroy(struct nfqnl_instance *inst)
  {
  	hlist_del_rcu(&inst->hlist);
  	call_rcu(&inst->rcu, instance_destroy_rcu);
  }
  
  static void
  instance_destroy(struct nfqnl_instance *inst)
  {
  	spin_lock(&instances_lock);
  	__instance_destroy(inst);
  	spin_unlock(&instances_lock);
  }
  
  static inline void
  __enqueue_entry(struct nfqnl_instance *queue, struct nf_queue_entry *entry)
  {
         list_add_tail(&entry->list, &queue->queue_list);
         queue->queue_total++;
  }
  
  static void
  __dequeue_entry(struct nfqnl_instance *queue, struct nf_queue_entry *entry)
  {
  	list_del(&entry->list);
  	queue->queue_total--;
  }
  
  static struct nf_queue_entry *
  find_dequeue_entry(struct nfqnl_instance *queue, unsigned int id)
  {
  	struct nf_queue_entry *entry = NULL, *i;
  
  	spin_lock_bh(&queue->lock);
  
  	list_for_each_entry(i, &queue->queue_list, list) {
  		if (i->id == id) {
  			entry = i;
  			break;
  		}
  	}
  
  	if (entry)
  		__dequeue_entry(queue, entry);
  
  	spin_unlock_bh(&queue->lock);
  
  	return entry;
  }
  
  static void
  nfqnl_flush(struct nfqnl_instance *queue, nfqnl_cmpfn cmpfn, unsigned long data)
  {
  	struct nf_queue_entry *entry, *next;
  
  	spin_lock_bh(&queue->lock);
  	list_for_each_entry_safe(entry, next, &queue->queue_list, list) {
  		if (!cmpfn || cmpfn(entry, data)) {
  			list_del(&entry->list);
  			queue->queue_total--;
  			nf_reinject(entry, NF_DROP);
  		}
  	}
  	spin_unlock_bh(&queue->lock);
  }
  
  static struct sk_buff *
  nfqnl_build_packet_message(struct nfqnl_instance *queue,
  			   struct nf_queue_entry *entry,
  			   __be32 **packet_id_ptr)
  {
  	sk_buff_data_t old_tail;
  	size_t size;
  	size_t data_len = 0;
  	struct sk_buff *skb;
  	struct nlattr *nla;
  	struct nfqnl_msg_packet_hdr *pmsg;
  	struct nlmsghdr *nlh;
  	struct nfgenmsg *nfmsg;
  	struct sk_buff *entskb = entry->skb;
  	struct net_device *indev;
  	struct net_device *outdev;
  
  	size =    NLMSG_SPACE(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 = entry->outdev;
  
  	switch ((enum nfqnl_config_mode)ACCESS_ONCE(queue->copy_mode)) {
  	case NFQNL_COPY_META:
  	case NFQNL_COPY_NONE:
  		break;
  
  	case NFQNL_COPY_PACKET:
  		if (entskb->ip_summed == CHECKSUM_PARTIAL &&
  		    skb_checksum_help(entskb))
  			return NULL;
  
  		data_len = ACCESS_ONCE(queue->copy_range);
  		if (data_len == 0 || data_len > entskb->len)
  			data_len = entskb->len;
  
  		size += nla_total_size(data_len);
  		break;
  	}
  
  
  	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 = entry->pf;
  	nfmsg->version = NFNETLINK_V0;
  	nfmsg->res_id = htons(queue->queue_num);
  
  	nla = __nla_reserve(skb, NFQA_PACKET_HDR, sizeof(*pmsg));
  	pmsg = nla_data(nla);
  	pmsg->hw_protocol	= entskb->protocol;
  	pmsg->hook		= entry->hook;
  	*packet_id_ptr		= &pmsg->packet_id;
  
  	indev = entry->indev;
  	if (indev) {
  #ifndef CONFIG_BRIDGE_NETFILTER
  		NLA_PUT_BE32(skb, NFQA_IFINDEX_INDEV, htonl(indev->ifindex));
  #else
  		if (entry->pf == PF_BRIDGE) {
  			/* Case 1: indev is physical input device, we need to
  			 * look for bridge group (when called from
  			 * netfilter_bridge) */
  			NLA_PUT_BE32(skb, NFQA_IFINDEX_PHYSINDEV,
  				     htonl(indev->ifindex));
  			/* this is the bridge group "brX" */
  			/* rcu_read_lock()ed by __nf_queue */
  			NLA_PUT_BE32(skb, NFQA_IFINDEX_INDEV,
  				     htonl(br_port_get_rcu(indev)->br->dev->ifindex));
  		} else {
  			/* Case 2: indev is bridge group, we need to look for
  			 * physical device (when called from ipv4) */
  			NLA_PUT_BE32(skb, NFQA_IFINDEX_INDEV,
  				     htonl(indev->ifindex));
  			if (entskb->nf_bridge && entskb->nf_bridge->physindev)
  				NLA_PUT_BE32(skb, NFQA_IFINDEX_PHYSINDEV,
  					     htonl(entskb->nf_bridge->physindev->ifindex));
  		}
  #endif
  	}
  
  	if (outdev) {
  #ifndef CONFIG_BRIDGE_NETFILTER
  		NLA_PUT_BE32(skb, NFQA_IFINDEX_OUTDEV, htonl(outdev->ifindex));
  #else
  		if (entry->pf == PF_BRIDGE) {
  			/* Case 1: outdev is physical output device, we need to
  			 * look for bridge group (when called from
  			 * netfilter_bridge) */
  			NLA_PUT_BE32(skb, NFQA_IFINDEX_PHYSOUTDEV,
  				     htonl(outdev->ifindex));
  			/* this is the bridge group "brX" */
  			/* rcu_read_lock()ed by __nf_queue */
  			NLA_PUT_BE32(skb, NFQA_IFINDEX_OUTDEV,
  				     htonl(br_port_get_rcu(outdev)->br->dev->ifindex));
  		} else {
  			/* Case 2: outdev is bridge group, we need to look for
  			 * physical output device (when called from ipv4) */
  			NLA_PUT_BE32(skb, NFQA_IFINDEX_OUTDEV,
  				     htonl(outdev->ifindex));
  			if (entskb->nf_bridge && entskb->nf_bridge->physoutdev)
  				NLA_PUT_BE32(skb, NFQA_IFINDEX_PHYSOUTDEV,
  					     htonl(entskb->nf_bridge->physoutdev->ifindex));
  		}
  #endif
  	}
  
  	if (entskb->mark)
  		NLA_PUT_BE32(skb, NFQA_MARK, htonl(entskb->mark));
  
  	if (indev && entskb->dev &&
  	    entskb->mac_header != entskb->network_header) {
  		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 sz = 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 = sz;
  
  		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);
  	if (net_ratelimit())
  		printk(KERN_ERR "nf_queue: error creating packet message\n");
  	return NULL;
  }
  
  static int
  nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
  {
  	struct sk_buff *nskb;
  	struct nfqnl_instance *queue;
  	int err = -ENOBUFS;
  	__be32 *packet_id_ptr;
  
  	/* rcu_read_lock()ed by nf_hook_slow() */
  	queue = instance_lookup(queuenum);
  	if (!queue) {
  		err = -ESRCH;
  		goto err_out;
  	}
  
  	if (queue->copy_mode == NFQNL_COPY_NONE) {
  		err = -EINVAL;
  		goto err_out;
  	}
  
  	nskb = nfqnl_build_packet_message(queue, entry, &packet_id_ptr);
  	if (nskb == NULL) {
  		err = -ENOMEM;
  		goto err_out;
  	}
  	spin_lock_bh(&queue->lock);
  
  	if (!queue->peer_pid) {
  		err = -EINVAL;
  		goto err_out_free_nskb;
  	}
  	if (queue->queue_total >= queue->queue_maxlen) {
  		queue->queue_dropped++;
  		if (net_ratelimit())
  			  printk(KERN_WARNING "nf_queue: full at %d entries, "
  				 "dropping packets(s).\n",
  				 queue->queue_total);
  		goto err_out_free_nskb;
  	}
  	entry->id = ++queue->id_sequence;
  	*packet_id_ptr = htonl(entry->id);
  
  	/* nfnetlink_unicast will either free the nskb or add it to a socket */
  	err = nfnetlink_unicast(nskb, &init_net, queue->peer_pid, MSG_DONTWAIT);
  	if (err < 0) {
  		queue->queue_user_dropped++;
  		goto err_out_unlock;
  	}
  
  	__enqueue_entry(queue, entry);
  
  	spin_unlock_bh(&queue->lock);
  	return 0;
  
  err_out_free_nskb:
  	kfree_skb(nskb);
  err_out_unlock:
  	spin_unlock_bh(&queue->lock);
  err_out:
  	return err;
  }
  
  static int
  nfqnl_mangle(void *data, int data_len, struct nf_queue_entry *e)
  {
  	struct sk_buff *nskb;
  	int diff;
  
  	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)) {
  			nskb = skb_copy_expand(e->skb, skb_headroom(e->skb),
  					       diff, GFP_ATOMIC);
  			if (!nskb) {
  				printk(KERN_WARNING "nf_queue: OOM "
  				      "in mangle, dropping packet\n");
  				return -ENOMEM;
  			}
  			kfree_skb(e->skb);
  			e->skb = nskb;
  		}
  		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 int
  nfqnl_set_mode(struct nfqnl_instance *queue,
  	       unsigned char mode, unsigned int range)
  {
  	int status = 0;
  
  	spin_lock_bh(&queue->lock);
  	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;
  
  	}
  	spin_unlock_bh(&queue->lock);
  
  	return status;
  }
  
  static int
  dev_cmp(struct nf_queue_entry *entry, unsigned long ifindex)
  {
  	if (entry->indev)
  		if (entry->indev->ifindex == ifindex)
  			return 1;
  	if (entry->outdev)
  		if (entry->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;
  
  	rcu_read_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_rcu(inst, tmp, head, hlist)
  			nfqnl_flush(inst, dev_cmp, ifindex);
  	}
  
  	rcu_read_unlock();
  }
  
  #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 (!net_eq(dev_net(dev), &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) {
  		int i;
  
  		/* destroy all instances for this pid */
  		spin_lock(&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);
  			}
  		}
  		spin_unlock(&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 const struct nla_policy nfqa_verdict_batch_policy[NFQA_MAX+1] = {
  	[NFQA_VERDICT_HDR]	= { .len = sizeof(struct nfqnl_msg_verdict_hdr) },
  	[NFQA_MARK]		= { .type = NLA_U32 },
  };
  
  static struct nfqnl_instance *verdict_instance_lookup(u16 queue_num, int nlpid)
  {
  	struct nfqnl_instance *queue;
  
  	queue = instance_lookup(queue_num);
  	if (!queue)
  		return ERR_PTR(-ENODEV);
  
  	if (queue->peer_pid != nlpid)
  		return ERR_PTR(-EPERM);
  
  	return queue;
  }
  
  static struct nfqnl_msg_verdict_hdr*
  verdicthdr_get(const struct nlattr * const nfqa[])
  {
  	struct nfqnl_msg_verdict_hdr *vhdr;
  	unsigned int verdict;
  
  	if (!nfqa[NFQA_VERDICT_HDR])
  		return NULL;
  
  	vhdr = nla_data(nfqa[NFQA_VERDICT_HDR]);
  	verdict = ntohl(vhdr->verdict) & NF_VERDICT_MASK;
  	if (verdict > NF_MAX_VERDICT || verdict == NF_STOLEN)
  		return NULL;
  	return vhdr;
  }
  
  static int nfq_id_after(unsigned int id, unsigned int max)
  {
  	return (int)(id - max) > 0;
  }
  
  static int
  nfqnl_recv_verdict_batch(struct sock *ctnl, struct sk_buff *skb,
  		   const struct nlmsghdr *nlh,
  		   const struct nlattr * const nfqa[])
  {
  	struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
  	struct nf_queue_entry *entry, *tmp;
  	unsigned int verdict, maxid;
  	struct nfqnl_msg_verdict_hdr *vhdr;
  	struct nfqnl_instance *queue;
  	LIST_HEAD(batch_list);
  	u16 queue_num = ntohs(nfmsg->res_id);
  
  	queue = verdict_instance_lookup(queue_num, NETLINK_CB(skb).pid);
  	if (IS_ERR(queue))
  		return PTR_ERR(queue);
  
  	vhdr = verdicthdr_get(nfqa);
  	if (!vhdr)
  		return -EINVAL;
  
  	verdict = ntohl(vhdr->verdict);
  	maxid = ntohl(vhdr->id);
  
  	spin_lock_bh(&queue->lock);
  
  	list_for_each_entry_safe(entry, tmp, &queue->queue_list, list) {
  		if (nfq_id_after(entry->id, maxid))
  			break;
  		__dequeue_entry(queue, entry);
  		list_add_tail(&entry->list, &batch_list);
  	}
  
  	spin_unlock_bh(&queue->lock);
  
  	if (list_empty(&batch_list))
  		return -ENOENT;
  
  	list_for_each_entry_safe(entry, tmp, &batch_list, list) {
  		if (nfqa[NFQA_MARK])
  			entry->skb->mark = ntohl(nla_get_be32(nfqa[NFQA_MARK]));
  		nf_reinject(entry, verdict);
  	}
  	return 0;
  }
  
  static int
  nfqnl_recv_verdict(struct sock *ctnl, struct sk_buff *skb,
  		   const struct nlmsghdr *nlh,
  		   const struct nlattr * const 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 nf_queue_entry *entry;
  
  	queue = instance_lookup(queue_num);
  	if (!queue)
  
  	queue = verdict_instance_lookup(queue_num, NETLINK_CB(skb).pid);
  	if (IS_ERR(queue))
  		return PTR_ERR(queue);
  
  	vhdr = verdicthdr_get(nfqa);
  	if (!vhdr)
  		return -EINVAL;
  
  	verdict = ntohl(vhdr->verdict);
  
  	entry = find_dequeue_entry(queue, ntohl(vhdr->id));
  	if (entry == NULL)
  		return -ENOENT;
  
  	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(nla_get_be32(nfqa[NFQA_MARK]));
  
  	nf_reinject(entry, verdict);
  	return 0;
  }
  
  static int
  nfqnl_recv_unsupp(struct sock *ctnl, struct sk_buff *skb,
  		  const struct nlmsghdr *nlh,
  		  const struct nlattr * const 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 const struct nf_queue_handler nfqh = {
  	.name 	= "nf_queue",
  	.outfn	= &nfqnl_enqueue_packet,
  };
  
  static int
  nfqnl_recv_config(struct sock *ctnl, struct sk_buff *skb,
  		  const struct nlmsghdr *nlh,
  		  const struct nlattr * const nfqa[])
  {
  	struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
  	u_int16_t queue_num = ntohs(nfmsg->res_id);
  	struct nfqnl_instance *queue;
  	struct nfqnl_msg_config_cmd *cmd = NULL;
  	int ret = 0;
  
  	if (nfqa[NFQA_CFG_CMD]) {
  		cmd = nla_data(nfqa[NFQA_CFG_CMD]);
  
  		/* Commands without queue context - might sleep */
  		switch (cmd->command) {
  		case NFQNL_CFG_CMD_PF_BIND:
  			return nf_register_queue_handler(ntohs(cmd->pf),
  							 &nfqh);
  		case NFQNL_CFG_CMD_PF_UNBIND:
  			return nf_unregister_queue_handler(ntohs(cmd->pf),
  							   &nfqh);
  		}
  	}
  
  	rcu_read_lock();
  	queue = instance_lookup(queue_num);
  	if (queue && queue->peer_pid != NETLINK_CB(skb).pid) {
  		ret = -EPERM;
  		goto err_out_unlock;
  	}
  
  	if (cmd != NULL) {
  		switch (cmd->command) {
  		case NFQNL_CFG_CMD_BIND:
  			if (queue) {
  				ret = -EBUSY;
  				goto err_out_unlock;
  			}
  			queue = instance_create(queue_num, NETLINK_CB(skb).pid);
  			if (IS_ERR(queue)) {
  				ret = PTR_ERR(queue);
  				goto err_out_unlock;
  			}
  			break;
  		case NFQNL_CFG_CMD_UNBIND:
  			if (!queue) {
  				ret = -ENODEV;
  				goto err_out_unlock;
  			}
  			instance_destroy(queue);
  			break;
  		case NFQNL_CFG_CMD_PF_BIND:
  		case NFQNL_CFG_CMD_PF_UNBIND:
  			break;
  		default:
  			ret = -ENOTSUPP;
  			break;
  		}
  	}
  
  	if (nfqa[NFQA_CFG_PARAMS]) {
  		struct nfqnl_msg_config_params *params;
  
  		if (!queue) {
  			ret = -ENODEV;
  			goto err_out_unlock;
  		}
  		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;
  
  		if (!queue) {
  			ret = -ENODEV;
  			goto err_out_unlock;
  		}
  		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);
  	}
  
  err_out_unlock:
  	rcu_read_unlock();
  	return ret;
  }
  
  static const struct nfnl_callback nfqnl_cb[NFQNL_MSG_MAX] = {
  	[NFQNL_MSG_PACKET]	= { .call_rcu = nfqnl_recv_unsupp,
  				    .attr_count = NFQA_MAX, },
  	[NFQNL_MSG_VERDICT]	= { .call_rcu = 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 },
  	[NFQNL_MSG_VERDICT_BATCH]={ .call_rcu = nfqnl_recv_verdict_batch,
  				    .attr_count = NFQA_MAX,
  				    .policy = nfqa_verdict_batch_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)
  	__acquires(instances_lock)
  {
  	spin_lock(&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)
  	__releases(instances_lock)
  {
  	spin_unlock(&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,
  			  inst->id_sequence, 1);
  }
  
  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;
  
  	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
  	if (!proc_create("nfnetlink_queue", 0440,
  			 proc_net_netfilter, &nfqnl_file_ops))
  		goto cleanup_subsys;
  #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);
  
  	rcu_barrier(); /* Wait for completion of call_rcu()'s */
  }
  
  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);
  