/*
   * This is a module which is used for logging packets to userspace via
   * nfetlink.
   *
   * (C) 2005 by Harald Welte <laforge@netfilter.org>
   *
   * Based on the old ipv4-only ipt_ULOG.c:
   * (C) 2000-2004 by Harald Welte <laforge@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/ip.h>
  #include <linux/ipv6.h>
  #include <linux/netdevice.h>
  #include <linux/netfilter.h>
  #include <linux/netlink.h>
  #include <linux/netfilter/nfnetlink.h>
  #include <linux/netfilter/nfnetlink_log.h>
  #include <linux/spinlock.h>
  #include <linux/sysctl.h>
  #include <linux/proc_fs.h>
  #include <linux/security.h>
  #include <linux/list.h>
  #include <linux/jhash.h>
  #include <linux/random.h>

  #include <linux/slab.h>

  #include <net/sock.h>

  #include <net/netfilter/nf_log.h>

  #include <net/netfilter/nfnetlink_log.h>

  
  #include <asm/atomic.h>

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

  #define NFULNL_NLBUFSIZ_DEFAULT	NLMSG_GOODSIZE

  #define NFULNL_TIMEOUT_DEFAULT 	100	/* every second */

  #define NFULNL_QTHRESH_DEFAULT 	100	/* 100 packets */

  #define NFULNL_COPY_RANGE_MAX	0xFFFF	/* max packet size is limited by 16-bit struct nfattr nfa_len field */

  
  #define PRINTR(x, args...)	do { if (net_ratelimit()) \
  				     printk(x, ## args); } while (0);

  struct nfulnl_instance {
  	struct hlist_node hlist;	/* global list of instances */
  	spinlock_t lock;
  	atomic_t use;			/* use count */
  
  	unsigned int qlen;		/* number of nlmsgs in skb */
  	struct sk_buff *skb;		/* pre-allocatd skb */

  	struct timer_list timer;
  	int peer_pid;			/* PID of the peer process */
  
  	/* configurable parameters */
  	unsigned int flushtimeout;	/* timeout until queue flush */
  	unsigned int nlbufsiz;		/* netlink buffer allocation size */
  	unsigned int qthreshold;	/* threshold of the queue */
  	u_int32_t copy_range;

  	u_int32_t seq;			/* instance-local sequential counter */

  	u_int16_t group_num;		/* number of this queue */

  	u_int16_t flags;

  	u_int8_t copy_mode;

  	struct rcu_head rcu;

  };

  static DEFINE_SPINLOCK(instances_lock);

  static atomic_t global_seq;

  
  #define INSTANCE_BUCKETS	16
  static struct hlist_head instance_table[INSTANCE_BUCKETS];
  static unsigned int hash_init;
  
  static inline u_int8_t instance_hashfn(u_int16_t group_num)
  {
  	return ((group_num & 0xff) % INSTANCE_BUCKETS);
  }
  
  static struct nfulnl_instance *
  __instance_lookup(u_int16_t group_num)
  {
  	struct hlist_head *head;
  	struct hlist_node *pos;
  	struct nfulnl_instance *inst;

  	head = &instance_table[instance_hashfn(group_num)];

  	hlist_for_each_entry_rcu(inst, pos, head, hlist) {

  		if (inst->group_num == group_num)
  			return inst;
  	}
  	return NULL;
  }
  
  static inline void
  instance_get(struct nfulnl_instance *inst)
  {
  	atomic_inc(&inst->use);
  }
  
  static struct nfulnl_instance *
  instance_lookup_get(u_int16_t group_num)
  {
  	struct nfulnl_instance *inst;

  	rcu_read_lock_bh();

  	inst = __instance_lookup(group_num);

  	if (inst && !atomic_inc_not_zero(&inst->use))
  		inst = NULL;

  	rcu_read_unlock_bh();

  
  	return inst;
  }

  static void nfulnl_instance_free_rcu(struct rcu_head *head)
  {
  	kfree(container_of(head, struct nfulnl_instance, rcu));
  	module_put(THIS_MODULE);
  }

  static void
  instance_put(struct nfulnl_instance *inst)
  {

  	if (inst && atomic_dec_and_test(&inst->use))
  		call_rcu_bh(&inst->rcu, nfulnl_instance_free_rcu);

  }
  
  static void nfulnl_timer(unsigned long data);
  
  static struct nfulnl_instance *
  instance_create(u_int16_t group_num, int pid)
  {
  	struct nfulnl_instance *inst;

  	int err;

  	spin_lock_bh(&instances_lock);

  	if (__instance_lookup(group_num)) {

  		err = -EEXIST;

  		goto out_unlock;
  	}

  	inst = kzalloc(sizeof(*inst), GFP_ATOMIC);

  	if (!inst) {
  		err = -ENOMEM;

  		goto out_unlock;

  	}

  	if (!try_module_get(THIS_MODULE)) {
  		kfree(inst);

  		err = -EAGAIN;

  		goto out_unlock;
  	}

  	INIT_HLIST_NODE(&inst->hlist);

  	spin_lock_init(&inst->lock);

  	/* needs to be two, since we _put() after creation */
  	atomic_set(&inst->use, 2);

  	setup_timer(&inst->timer, nfulnl_timer, (unsigned long)inst);

  
  	inst->peer_pid = pid;
  	inst->group_num = group_num;
  
  	inst->qthreshold 	= NFULNL_QTHRESH_DEFAULT;
  	inst->flushtimeout 	= NFULNL_TIMEOUT_DEFAULT;
  	inst->nlbufsiz 		= NFULNL_NLBUFSIZ_DEFAULT;
  	inst->copy_mode 	= NFULNL_COPY_PACKET;

  	inst->copy_range 	= NFULNL_COPY_RANGE_MAX;

  	hlist_add_head_rcu(&inst->hlist,

  		       &instance_table[instance_hashfn(group_num)]);

  	spin_unlock_bh(&instances_lock);

  
  	return inst;

  out_unlock:

  	spin_unlock_bh(&instances_lock);

  	return ERR_PTR(err);

  }

  static void __nfulnl_flush(struct nfulnl_instance *inst);

  /* called with BH disabled */

  static void

  __instance_destroy(struct nfulnl_instance *inst)

  {
  	/* first pull it out of the global list */

  	hlist_del_rcu(&inst->hlist);

  	/* then flush all pending packets from skb */

  	spin_lock(&inst->lock);
  
  	/* lockless readers wont be able to use us */
  	inst->copy_mode = NFULNL_COPY_DISABLED;

  	if (inst->skb)
  		__nfulnl_flush(inst);

  	spin_unlock(&inst->lock);

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

  }
  
  static inline void

  instance_destroy(struct nfulnl_instance *inst)
  {

  	spin_lock_bh(&instances_lock);

  	__instance_destroy(inst);

  	spin_unlock_bh(&instances_lock);

  }
  
  static int
  nfulnl_set_mode(struct nfulnl_instance *inst, u_int8_t mode,
  		  unsigned int range)
  {
  	int status = 0;
  
  	spin_lock_bh(&inst->lock);

  	switch (mode) {
  	case NFULNL_COPY_NONE:
  	case NFULNL_COPY_META:
  		inst->copy_mode = mode;
  		inst->copy_range = 0;
  		break;

  	case NFULNL_COPY_PACKET:
  		inst->copy_mode = mode;

  		inst->copy_range = min_t(unsigned int,
  					 range, NFULNL_COPY_RANGE_MAX);

  		break;

  	default:
  		status = -EINVAL;
  		break;
  	}
  
  	spin_unlock_bh(&inst->lock);
  
  	return status;
  }
  
  static int
  nfulnl_set_nlbufsiz(struct nfulnl_instance *inst, u_int32_t nlbufsiz)
  {
  	int status;
  
  	spin_lock_bh(&inst->lock);
  	if (nlbufsiz < NFULNL_NLBUFSIZ_DEFAULT)
  		status = -ERANGE;
  	else if (nlbufsiz > 131072)
  		status = -ERANGE;
  	else {
  		inst->nlbufsiz = nlbufsiz;
  		status = 0;
  	}
  	spin_unlock_bh(&inst->lock);
  
  	return status;
  }
  
  static int
  nfulnl_set_timeout(struct nfulnl_instance *inst, u_int32_t timeout)
  {
  	spin_lock_bh(&inst->lock);
  	inst->flushtimeout = timeout;
  	spin_unlock_bh(&inst->lock);
  
  	return 0;
  }
  
  static int
  nfulnl_set_qthresh(struct nfulnl_instance *inst, u_int32_t qthresh)
  {
  	spin_lock_bh(&inst->lock);
  	inst->qthreshold = qthresh;
  	spin_unlock_bh(&inst->lock);
  
  	return 0;
  }

  static int
  nfulnl_set_flags(struct nfulnl_instance *inst, u_int16_t flags)
  {
  	spin_lock_bh(&inst->lock);

  	inst->flags = flags;

  	spin_unlock_bh(&inst->lock);
  
  	return 0;
  }

  static struct sk_buff *
  nfulnl_alloc_skb(unsigned int inst_size, unsigned int pkt_size)

  {
  	struct sk_buff *skb;

  	unsigned int n;

  	/* alloc skb which should be big enough for a whole multipart
  	 * message.  WARNING: has to be <= 128k due to slab restrictions */

  	n = max(inst_size, pkt_size);
  	skb = alloc_skb(n, GFP_ATOMIC);

  	if (!skb) {

  		pr_notice("nfnetlink_log: can't alloc whole buffer (%u bytes)
  ",

  			inst_size);

  		if (n > pkt_size) {
  			/* try to allocate only as much as we need for current
  			 * packet */

  			skb = alloc_skb(pkt_size, GFP_ATOMIC);
  			if (!skb)

  				pr_err("nfnetlink_log: can't even alloc %u "

  				       "bytes
  ", pkt_size);
  		}

  	}
  
  	return skb;
  }
  
  static int
  __nfulnl_send(struct nfulnl_instance *inst)
  {

  	int status = -1;

  	if (inst->qlen > 1)

  		NLMSG_PUT(inst->skb, 0, 0,
  			  NLMSG_DONE,
  			  sizeof(struct nfgenmsg));

  	status = nfnetlink_unicast(inst->skb, &init_net, inst->peer_pid,
  				   MSG_DONTWAIT);

  
  	inst->qlen = 0;
  	inst->skb = NULL;

  nlmsg_failure:

  	return status;
  }

  static void
  __nfulnl_flush(struct nfulnl_instance *inst)
  {
  	/* timer holds a reference */
  	if (del_timer(&inst->timer))
  		instance_put(inst);
  	if (inst->skb)
  		__nfulnl_send(inst);
  }

  static void
  nfulnl_timer(unsigned long data)

  {

  	struct nfulnl_instance *inst = (struct nfulnl_instance *)data;

  	spin_lock_bh(&inst->lock);

  	if (inst->skb)
  		__nfulnl_send(inst);

  	spin_unlock_bh(&inst->lock);

  	instance_put(inst);

  }

  /* This is an inline function, we don't really care about a long
   * list of arguments */

  static inline int

  __build_packet_message(struct nfulnl_instance *inst,

  			const struct sk_buff *skb,

  			unsigned int data_len,

  			u_int8_t pf,

  			unsigned int hooknum,
  			const struct net_device *indev,
  			const struct net_device *outdev,
  			const struct nf_loginfo *li,

  			const char *prefix, unsigned int plen)

  {

  	struct nfulnl_msg_packet_hdr pmsg;
  	struct nlmsghdr *nlh;
  	struct nfgenmsg *nfmsg;

  	__be32 tmp_uint;

  	sk_buff_data_t old_tail = inst->skb->tail;

  	nlh = NLMSG_PUT(inst->skb, 0, 0,

  			NFNL_SUBSYS_ULOG << 8 | NFULNL_MSG_PACKET,
  			sizeof(struct nfgenmsg));
  	nfmsg = NLMSG_DATA(nlh);
  	nfmsg->nfgen_family = pf;
  	nfmsg->version = NFNETLINK_V0;
  	nfmsg->res_id = htons(inst->group_num);

  	pmsg.hw_protocol	= skb->protocol;

  	pmsg.hook		= hooknum;

  	NLA_PUT(inst->skb, NFULA_PACKET_HDR, sizeof(pmsg), &pmsg);

  	if (prefix)

  		NLA_PUT(inst->skb, NFULA_PREFIX, plen, prefix);

  
  	if (indev) {

  #ifndef CONFIG_BRIDGE_NETFILTER

  		NLA_PUT_BE32(inst->skb, NFULA_IFINDEX_INDEV,
  			     htonl(indev->ifindex));

  #else
  		if (pf == PF_BRIDGE) {
  			/* Case 1: outdev is physical input device, we need to
  			 * look for bridge group (when called from
  			 * netfilter_bridge) */

  			NLA_PUT_BE32(inst->skb, NFULA_IFINDEX_PHYSINDEV,
  				     htonl(indev->ifindex));

  			/* this is the bridge group "brX" */

  			/* rcu_read_lock()ed by nf_hook_slow or nf_log_packet */

  			NLA_PUT_BE32(inst->skb, NFULA_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(inst->skb, NFULA_IFINDEX_INDEV,
  				     htonl(indev->ifindex));
  			if (skb->nf_bridge && skb->nf_bridge->physindev)
  				NLA_PUT_BE32(inst->skb, NFULA_IFINDEX_PHYSINDEV,
  					     htonl(skb->nf_bridge->physindev->ifindex));

  		}
  #endif

  	}
  
  	if (outdev) {
  		tmp_uint = htonl(outdev->ifindex);

  #ifndef CONFIG_BRIDGE_NETFILTER

  		NLA_PUT_BE32(inst->skb, NFULA_IFINDEX_OUTDEV,
  			     htonl(outdev->ifindex));

  #else
  		if (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(inst->skb, NFULA_IFINDEX_PHYSOUTDEV,
  				     htonl(outdev->ifindex));

  			/* this is the bridge group "brX" */

  			/* rcu_read_lock()ed by nf_hook_slow or nf_log_packet */

  			NLA_PUT_BE32(inst->skb, NFULA_IFINDEX_OUTDEV,

  				     htonl(br_port_get_rcu(outdev)->br->dev->ifindex));

  		} else {
  			/* Case 2: indev is a bridge group, we need to look
  			 * for physical device (when called from ipv4) */

  			NLA_PUT_BE32(inst->skb, NFULA_IFINDEX_OUTDEV,
  				     htonl(outdev->ifindex));
  			if (skb->nf_bridge && skb->nf_bridge->physoutdev)
  				NLA_PUT_BE32(inst->skb, NFULA_IFINDEX_PHYSOUTDEV,
  					     htonl(skb->nf_bridge->physoutdev->ifindex));

  		}
  #endif

  	}

  	if (skb->mark)
  		NLA_PUT_BE32(inst->skb, NFULA_MARK, htonl(skb->mark));

  	if (indev && skb->dev) {

  		struct nfulnl_msg_packet_hw phw;

  		int len = dev_parse_header(skb, phw.hw_addr);
  		if (len > 0) {
  			phw.hw_addrlen = htons(len);

  			NLA_PUT(inst->skb, NFULA_HWADDR, sizeof(phw), &phw);

  		}

  	}

  	if (indev && skb_mac_header_was_set(skb)) {
  		NLA_PUT_BE16(inst->skb, NFULA_HWTYPE, htons(skb->dev->type));
  		NLA_PUT_BE16(inst->skb, NFULA_HWLEN,
  			     htons(skb->dev->hard_header_len));
  		NLA_PUT(inst->skb, NFULA_HWHEADER, skb->dev->hard_header_len,
  			skb_mac_header(skb));
  	}

  	if (skb->tstamp.tv64) {

  		struct nfulnl_msg_packet_timestamp ts;

  		struct timeval tv = ktime_to_timeval(skb->tstamp);
  		ts.sec = cpu_to_be64(tv.tv_sec);
  		ts.usec = cpu_to_be64(tv.tv_usec);

  		NLA_PUT(inst->skb, NFULA_TIMESTAMP, sizeof(ts), &ts);

  	}
  
  	/* UID */
  	if (skb->sk) {
  		read_lock_bh(&skb->sk->sk_callback_lock);
  		if (skb->sk->sk_socket && skb->sk->sk_socket->file) {

  			struct file *file = skb->sk->sk_socket->file;
  			__be32 uid = htonl(file->f_cred->fsuid);
  			__be32 gid = htonl(file->f_cred->fsgid);

  			/* need to unlock here since NLA_PUT may goto */

  			read_unlock_bh(&skb->sk->sk_callback_lock);

  			NLA_PUT_BE32(inst->skb, NFULA_UID, uid);

  			NLA_PUT_BE32(inst->skb, NFULA_GID, gid);

  		} else
  			read_unlock_bh(&skb->sk->sk_callback_lock);
  	}

  	/* local sequence number */

  	if (inst->flags & NFULNL_CFG_F_SEQ)
  		NLA_PUT_BE32(inst->skb, NFULA_SEQ, htonl(inst->seq++));

  	/* global sequence number */

  	if (inst->flags & NFULNL_CFG_F_SEQ_GLOBAL)
  		NLA_PUT_BE32(inst->skb, NFULA_SEQ_GLOBAL,
  			     htonl(atomic_inc_return(&global_seq)));

  	if (data_len) {

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

  		if (skb_tailroom(inst->skb) < nla_total_size(data_len)) {

  			printk(KERN_WARNING "nfnetlink_log: no tailroom!
  ");
  			goto nlmsg_failure;
  		}

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

  		if (skb_copy_bits(skb, 0, nla_data(nla), data_len))

  			BUG();
  	}

  	nlh->nlmsg_len = inst->skb->tail - old_tail;
  	return 0;
  
  nlmsg_failure:

  nla_put_failure:

  	PRINTR(KERN_ERR "nfnetlink_log: error creating log nlmsg
  ");
  	return -1;
  }
  
  #define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
  
  static struct nf_loginfo default_loginfo = {
  	.type =		NF_LOG_TYPE_ULOG,
  	.u = {
  		.ulog = {
  			.copy_len	= 0xffff,
  			.group		= 0,
  			.qthreshold	= 1,
  		},
  	},
  };
  
  /* log handler for internal netfilter logging api */

  void

  nfulnl_log_packet(u_int8_t pf,

  		  unsigned int hooknum,
  		  const struct sk_buff *skb,
  		  const struct net_device *in,
  		  const struct net_device *out,
  		  const struct nf_loginfo *li_user,
  		  const char *prefix)
  {
  	unsigned int size, data_len;
  	struct nfulnl_instance *inst;
  	const struct nf_loginfo *li;
  	unsigned int qthreshold;

  	unsigned int plen;

  	if (li_user && li_user->type == NF_LOG_TYPE_ULOG)

  		li = li_user;
  	else
  		li = &default_loginfo;
  
  	inst = instance_lookup_get(li->u.ulog.group);
  	if (!inst)

  		return;

  	plen = 0;
  	if (prefix)

  		plen = strlen(prefix) + 1;

  	/* FIXME: do we want to make the size calculation conditional based on
  	 * what is actually present?  way more branches and checks, but more
  	 * memory efficient... */

  	size =    NLMSG_SPACE(sizeof(struct nfgenmsg))

  		+ nla_total_size(sizeof(struct nfulnl_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(u_int32_t))	/* uid */

  		+ nla_total_size(sizeof(u_int32_t))	/* gid */

  		+ nla_total_size(plen)			/* prefix */
  		+ nla_total_size(sizeof(struct nfulnl_msg_packet_hw))
  		+ nla_total_size(sizeof(struct nfulnl_msg_packet_timestamp));

  	if (in && skb_mac_header_was_set(skb)) {
  		size +=   nla_total_size(skb->dev->hard_header_len)
  			+ nla_total_size(sizeof(u_int16_t))	/* hwtype */
  			+ nla_total_size(sizeof(u_int16_t));	/* hwlen */
  	}

  	spin_lock_bh(&inst->lock);

  	if (inst->flags & NFULNL_CFG_F_SEQ)

  		size += nla_total_size(sizeof(u_int32_t));

  	if (inst->flags & NFULNL_CFG_F_SEQ_GLOBAL)

  		size += nla_total_size(sizeof(u_int32_t));

  	qthreshold = inst->qthreshold;
  	/* per-rule qthreshold overrides per-instance */

  	if (li->u.ulog.qthreshold)
  		if (qthreshold > li->u.ulog.qthreshold)
  			qthreshold = li->u.ulog.qthreshold;

  	switch (inst->copy_mode) {
  	case NFULNL_COPY_META:
  	case NFULNL_COPY_NONE:
  		data_len = 0;
  		break;

  	case NFULNL_COPY_PACKET:

  		if (inst->copy_range == 0

  		    || inst->copy_range > skb->len)
  			data_len = skb->len;
  		else
  			data_len = inst->copy_range;

  		size += nla_total_size(data_len);

  		break;

  	case NFULNL_COPY_DISABLED:

  	default:

  		goto unlock_and_release;

  	}

  	if (inst->skb &&
  	    size > skb_tailroom(inst->skb) - sizeof(struct nfgenmsg)) {

  		/* either the queue len is too high or we don't have
  		 * enough room in the skb left. flush to userspace. */

  		__nfulnl_flush(inst);

  	}

  	if (!inst->skb) {
  		inst->skb = nfulnl_alloc_skb(inst->nlbufsiz, size);
  		if (!inst->skb)

  			goto alloc_failure;

  	}

  	inst->qlen++;
  
  	__build_packet_message(inst, skb, data_len, pf,

  				hooknum, in, out, li, prefix, plen);

  	if (inst->qlen >= qthreshold)
  		__nfulnl_flush(inst);

  	/* timer_pending always called within inst->lock, so there
  	 * is no chance of a race here */

  	else if (!timer_pending(&inst->timer)) {

  		instance_get(inst);
  		inst->timer.expires = jiffies + (inst->flushtimeout*HZ/100);
  		add_timer(&inst->timer);
  	}

  unlock_and_release:
  	spin_unlock_bh(&inst->lock);
  	instance_put(inst);

  	return;
  
  alloc_failure:

  	/* FIXME: statistics */

  	goto unlock_and_release;

  }

  EXPORT_SYMBOL_GPL(nfulnl_log_packet);

  
  static int
  nfulnl_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_bh(&instances_lock);

  		for  (i = 0; i < INSTANCE_BUCKETS; i++) {
  			struct hlist_node *tmp, *t2;
  			struct nfulnl_instance *inst;
  			struct hlist_head *head = &instance_table[i];
  
  			hlist_for_each_entry_safe(inst, tmp, t2, head, hlist) {

  				if ((net_eq(n->net, &init_net)) &&

  				    (n->pid == inst->peer_pid))

  					__instance_destroy(inst);
  			}
  		}

  		spin_unlock_bh(&instances_lock);

  	}
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block nfulnl_rtnl_notifier = {
  	.notifier_call	= nfulnl_rcv_nl_event,
  };
  
  static int
  nfulnl_recv_unsupp(struct sock *ctnl, struct sk_buff *skb,

  		   const struct nlmsghdr *nlh,
  		   const struct nlattr * const nfqa[])

  {
  	return -ENOTSUPP;
  }

  static struct nf_logger nfulnl_logger __read_mostly = {

  	.name	= "nfnetlink_log",
  	.logfn	= &nfulnl_log_packet,
  	.me	= THIS_MODULE,
  };

  static const struct nla_policy nfula_cfg_policy[NFULA_CFG_MAX+1] = {
  	[NFULA_CFG_CMD]		= { .len = sizeof(struct nfulnl_msg_config_cmd) },
  	[NFULA_CFG_MODE]	= { .len = sizeof(struct nfulnl_msg_config_mode) },
  	[NFULA_CFG_TIMEOUT]	= { .type = NLA_U32 },
  	[NFULA_CFG_QTHRESH]	= { .type = NLA_U32 },
  	[NFULA_CFG_NLBUFSIZ]	= { .type = NLA_U32 },
  	[NFULA_CFG_FLAGS]	= { .type = NLA_U16 },

  };
  
  static int
  nfulnl_recv_config(struct sock *ctnl, struct sk_buff *skb,

  		   const struct nlmsghdr *nlh,
  		   const struct nlattr * const nfula[])

  {
  	struct nfgenmsg *nfmsg = NLMSG_DATA(nlh);
  	u_int16_t group_num = ntohs(nfmsg->res_id);
  	struct nfulnl_instance *inst;

  	struct nfulnl_msg_config_cmd *cmd = NULL;

  	int ret = 0;

  	if (nfula[NFULA_CFG_CMD]) {
  		u_int8_t pf = nfmsg->nfgen_family;
  		cmd = nla_data(nfula[NFULA_CFG_CMD]);
  
  		/* Commands without queue context */
  		switch (cmd->command) {
  		case NFULNL_CFG_CMD_PF_BIND:

  			return nf_log_bind_pf(pf, &nfulnl_logger);

  		case NFULNL_CFG_CMD_PF_UNBIND:

  			nf_log_unbind_pf(pf);

  			return 0;
  		}
  	}

  	inst = instance_lookup_get(group_num);

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

  	if (cmd != NULL) {

  		switch (cmd->command) {
  		case NFULNL_CFG_CMD_BIND:
  			if (inst) {
  				ret = -EBUSY;
  				goto out_put;
  			}
  
  			inst = instance_create(group_num,
  					       NETLINK_CB(skb).pid);

  			if (IS_ERR(inst)) {
  				ret = PTR_ERR(inst);

  				goto out;

  			}
  			break;
  		case NFULNL_CFG_CMD_UNBIND:
  			if (!inst) {
  				ret = -ENODEV;

  				goto out;

  			}

  			instance_destroy(inst);

  			goto out_put;

  		default:

  			ret = -ENOTSUPP;

  			break;
  		}

  	}

  	if (nfula[NFULA_CFG_MODE]) {

  		struct nfulnl_msg_config_mode *params;

  		params = nla_data(nfula[NFULA_CFG_MODE]);

  		if (!inst) {
  			ret = -ENODEV;
  			goto out;
  		}

  		nfulnl_set_mode(inst, params->copy_mode,

  				ntohl(params->copy_range));

  	}

  	if (nfula[NFULA_CFG_TIMEOUT]) {

  		__be32 timeout = nla_get_be32(nfula[NFULA_CFG_TIMEOUT]);

  		if (!inst) {
  			ret = -ENODEV;
  			goto out;
  		}

  		nfulnl_set_timeout(inst, ntohl(timeout));
  	}

  	if (nfula[NFULA_CFG_NLBUFSIZ]) {

  		__be32 nlbufsiz = nla_get_be32(nfula[NFULA_CFG_NLBUFSIZ]);

  		if (!inst) {
  			ret = -ENODEV;
  			goto out;
  		}

  		nfulnl_set_nlbufsiz(inst, ntohl(nlbufsiz));
  	}

  	if (nfula[NFULA_CFG_QTHRESH]) {

  		__be32 qthresh = nla_get_be32(nfula[NFULA_CFG_QTHRESH]);

  		if (!inst) {
  			ret = -ENODEV;
  			goto out;
  		}

  		nfulnl_set_qthresh(inst, ntohl(qthresh));
  	}

  	if (nfula[NFULA_CFG_FLAGS]) {

  		__be16 flags = nla_get_be16(nfula[NFULA_CFG_FLAGS]);

  
  		if (!inst) {
  			ret = -ENODEV;
  			goto out;
  		}

  		nfulnl_set_flags(inst, ntohs(flags));

  	}

  out_put:
  	instance_put(inst);

  out:

  	return ret;
  }

  static const struct nfnl_callback nfulnl_cb[NFULNL_MSG_MAX] = {

  	[NFULNL_MSG_PACKET]	= { .call = nfulnl_recv_unsupp,

  				    .attr_count = NFULA_MAX, },

  	[NFULNL_MSG_CONFIG]	= { .call = nfulnl_recv_config,

  				    .attr_count = NFULA_CFG_MAX,
  				    .policy = nfula_cfg_policy },

  };

  static const struct nfnetlink_subsystem nfulnl_subsys = {

  	.name		= "log",
  	.subsys_id	= NFNL_SUBSYS_ULOG,
  	.cb_count	= NFULNL_MSG_MAX,

  	.cb		= nfulnl_cb,
  };
  
  #ifdef CONFIG_PROC_FS
  struct iter_state {
  	unsigned int bucket;
  };

  static struct hlist_node *get_first(struct iter_state *st)

  {

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

  			return rcu_dereference_bh(instance_table[st->bucket].first);

  	}
  	return NULL;
  }

  static struct hlist_node *get_next(struct iter_state *st, struct hlist_node *h)

  {

  	h = rcu_dereference_bh(h->next);

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

  		h = rcu_dereference_bh(instance_table[st->bucket].first);

  	}
  	return h;
  }

  static struct hlist_node *get_idx(struct iter_state *st, loff_t pos)

  {
  	struct hlist_node *head;

  	head = get_first(st);

  
  	if (head)

  		while (pos && (head = get_next(st, head)))

  			pos--;
  	return pos ? NULL : head;
  }
  
  static void *seq_start(struct seq_file *seq, loff_t *pos)

  	__acquires(rcu_bh)

  {

  	rcu_read_lock_bh();

  	return get_idx(seq->private, *pos);

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

  	return get_next(s->private, v);

  }
  
  static void seq_stop(struct seq_file *s, void *v)

  	__releases(rcu_bh)

  {

  	rcu_read_unlock_bh();

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

  	return seq_printf(s, "%5d %6d %5d %1d %5d %6d %2d
  ",

  			  inst->group_num,

  			  inst->peer_pid, inst->qlen,

  			  inst->copy_mode, inst->copy_range,
  			  inst->flushtimeout, atomic_read(&inst->use));
  }

  static const struct seq_operations nful_seq_ops = {

  	.start	= seq_start,
  	.next	= seq_next,
  	.stop	= seq_stop,
  	.show	= seq_show,
  };
  
  static int nful_open(struct inode *inode, struct file *file)
  {

  	return seq_open_private(file, &nful_seq_ops,
  			sizeof(struct iter_state));

  }

  static const struct file_operations nful_file_ops = {

  	.owner	 = THIS_MODULE,
  	.open	 = nful_open,
  	.read	 = seq_read,
  	.llseek	 = seq_lseek,
  	.release = seq_release_private,
  };
  
  #endif /* PROC_FS */

  static int __init nfnetlink_log_init(void)

  {
  	int i, status = -ENOMEM;

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

  	/* it's not really all that important to have a random value, so
  	 * we can do this from the init function, even if there hasn't
  	 * been that much entropy yet */
  	get_random_bytes(&hash_init, sizeof(hash_init));
  
  	netlink_register_notifier(&nfulnl_rtnl_notifier);
  	status = nfnetlink_subsys_register(&nfulnl_subsys);
  	if (status < 0) {
  		printk(KERN_ERR "log: failed to create netlink socket
  ");
  		goto cleanup_netlink_notifier;
  	}

  	status = nf_log_register(NFPROTO_UNSPEC, &nfulnl_logger);
  	if (status < 0) {
  		printk(KERN_ERR "log: failed to register logger
  ");
  		goto cleanup_subsys;
  	}

  #ifdef CONFIG_PROC_FS

  	if (!proc_create("nfnetlink_log", 0440,
  			 proc_net_netfilter, &nful_file_ops))

  		goto cleanup_logger;

  #endif

  	return status;

  #ifdef CONFIG_PROC_FS

  cleanup_logger:
  	nf_log_unregister(&nfulnl_logger);
  #endif

  cleanup_subsys:

  	nfnetlink_subsys_unregister(&nfulnl_subsys);
  cleanup_netlink_notifier:
  	netlink_unregister_notifier(&nfulnl_rtnl_notifier);
  	return status;
  }

  static void __exit nfnetlink_log_fini(void)

  {

  	nf_log_unregister(&nfulnl_logger);

  #ifdef CONFIG_PROC_FS
  	remove_proc_entry("nfnetlink_log", proc_net_netfilter);
  #endif
  	nfnetlink_subsys_unregister(&nfulnl_subsys);
  	netlink_unregister_notifier(&nfulnl_rtnl_notifier);

  }
  
  MODULE_DESCRIPTION("netfilter userspace logging");
  MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  MODULE_LICENSE("GPL");

  MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ULOG);

  module_init(nfnetlink_log_init);
  module_exit(nfnetlink_log_fini);