/*
   * x_tables core - Backend for {ip,ip6,arp}_tables
   *
   * Copyright (C) 2006-2006 Harald Welte <laforge@netfilter.org>

   * Copyright (C) 2006-2012 Patrick McHardy <kaber@trash.net>

   *
   * Based on existing ip_tables code which is
   *   Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
   *   Copyright (C) 2000-2005 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.
   *
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/kernel.h>

  #include <linux/module.h>

  #include <linux/socket.h>
  #include <linux/net.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/string.h>
  #include <linux/vmalloc.h>

  #include <linux/mutex.h>

  #include <linux/mm.h>

  #include <linux/slab.h>

  #include <linux/audit.h>

  #include <net/net_namespace.h>

  
  #include <linux/netfilter/x_tables.h>
  #include <linux/netfilter_arp.h>

  #include <linux/netfilter_ipv4/ip_tables.h>
  #include <linux/netfilter_ipv6/ip6_tables.h>
  #include <linux/netfilter_arp/arp_tables.h>

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

  MODULE_DESCRIPTION("{ip,ip6,arp,eb}_tables backend module");

  
  #define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1))

  struct compat_delta {

  	unsigned int offset; /* offset in kernel */
  	int delta; /* delta in 32bit user land */

  };

  struct xt_af {

  	struct mutex mutex;

  	struct list_head match;
  	struct list_head target;

  #ifdef CONFIG_COMPAT

  	struct mutex compat_mutex;

  	struct compat_delta *compat_tab;
  	unsigned int number; /* number of slots in compat_tab[] */
  	unsigned int cur; /* number of used slots in compat_tab[] */

  #endif

  };
  
  static struct xt_af *xt;

  static const char *const xt_prefix[NFPROTO_NUMPROTO] = {
  	[NFPROTO_UNSPEC] = "x",
  	[NFPROTO_IPV4]   = "ip",
  	[NFPROTO_ARP]    = "arp",
  	[NFPROTO_BRIDGE] = "eb",
  	[NFPROTO_IPV6]   = "ip6",

  };

  /* Allow this many total (re)entries. */
  static const unsigned int xt_jumpstack_multiplier = 2;

  /* Registration hooks for targets. */
  int

  xt_register_target(struct xt_target *target)

  {

  	u_int8_t af = target->family;
  	int ret;

  	ret = mutex_lock_interruptible(&xt[af].mutex);

  	if (ret != 0)
  		return ret;
  	list_add(&target->list, &xt[af].target);

  	mutex_unlock(&xt[af].mutex);

  	return ret;
  }
  EXPORT_SYMBOL(xt_register_target);
  
  void

  xt_unregister_target(struct xt_target *target)

  {

  	u_int8_t af = target->family;

  	mutex_lock(&xt[af].mutex);

  	list_del(&target->list);

  	mutex_unlock(&xt[af].mutex);

  }
  EXPORT_SYMBOL(xt_unregister_target);
  
  int

  xt_register_targets(struct xt_target *target, unsigned int n)
  {
  	unsigned int i;
  	int err = 0;
  
  	for (i = 0; i < n; i++) {
  		err = xt_register_target(&target[i]);
  		if (err)
  			goto err;
  	}
  	return err;
  
  err:
  	if (i > 0)
  		xt_unregister_targets(target, i);
  	return err;
  }
  EXPORT_SYMBOL(xt_register_targets);
  
  void
  xt_unregister_targets(struct xt_target *target, unsigned int n)
  {

  	while (n-- > 0)
  		xt_unregister_target(&target[n]);

  }
  EXPORT_SYMBOL(xt_unregister_targets);
  
  int

  xt_register_match(struct xt_match *match)

  {

  	u_int8_t af = match->family;
  	int ret;

  	ret = mutex_lock_interruptible(&xt[af].mutex);

  	if (ret != 0)
  		return ret;
  
  	list_add(&match->list, &xt[af].match);

  	mutex_unlock(&xt[af].mutex);

  
  	return ret;
  }
  EXPORT_SYMBOL(xt_register_match);
  
  void

  xt_unregister_match(struct xt_match *match)

  {

  	u_int8_t af = match->family;

  	mutex_lock(&xt[af].mutex);

  	list_del(&match->list);

  	mutex_unlock(&xt[af].mutex);

  }
  EXPORT_SYMBOL(xt_unregister_match);

  int
  xt_register_matches(struct xt_match *match, unsigned int n)
  {
  	unsigned int i;
  	int err = 0;
  
  	for (i = 0; i < n; i++) {
  		err = xt_register_match(&match[i]);
  		if (err)
  			goto err;
  	}
  	return err;
  
  err:
  	if (i > 0)
  		xt_unregister_matches(match, i);
  	return err;
  }
  EXPORT_SYMBOL(xt_register_matches);
  
  void
  xt_unregister_matches(struct xt_match *match, unsigned int n)
  {

  	while (n-- > 0)
  		xt_unregister_match(&match[n]);

  }
  EXPORT_SYMBOL(xt_unregister_matches);

  
  /*
   * These are weird, but module loading must not be done with mutex
   * held (since they will register), and we have to have a single

   * function to use.

   */
  
  /* Find match, grabs ref.  Returns ERR_PTR() on error. */

  struct xt_match *xt_find_match(u8 af, const char *name, u8 revision)

  {
  	struct xt_match *m;

  	int err = -ENOENT;

  	if (mutex_lock_interruptible(&xt[af].mutex) != 0)

  		return ERR_PTR(-EINTR);
  
  	list_for_each_entry(m, &xt[af].match, list) {
  		if (strcmp(m->name, name) == 0) {
  			if (m->revision == revision) {
  				if (try_module_get(m->me)) {

  					mutex_unlock(&xt[af].mutex);

  					return m;
  				}
  			} else
  				err = -EPROTOTYPE; /* Found something. */
  		}
  	}

  	mutex_unlock(&xt[af].mutex);

  
  	if (af != NFPROTO_UNSPEC)
  		/* Try searching again in the family-independent list */
  		return xt_find_match(NFPROTO_UNSPEC, name, revision);

  	return ERR_PTR(err);
  }
  EXPORT_SYMBOL(xt_find_match);

  struct xt_match *
  xt_request_find_match(uint8_t nfproto, const char *name, uint8_t revision)
  {
  	struct xt_match *match;

  	match = xt_find_match(nfproto, name, revision);
  	if (IS_ERR(match)) {
  		request_module("%st_%s", xt_prefix[nfproto], name);
  		match = xt_find_match(nfproto, name, revision);
  	}
  
  	return match;

  }
  EXPORT_SYMBOL_GPL(xt_request_find_match);

  /* Find target, grabs ref.  Returns ERR_PTR() on error. */

  struct xt_target *xt_find_target(u8 af, const char *name, u8 revision)

  {
  	struct xt_target *t;

  	int err = -ENOENT;

  	if (mutex_lock_interruptible(&xt[af].mutex) != 0)

  		return ERR_PTR(-EINTR);
  
  	list_for_each_entry(t, &xt[af].target, list) {
  		if (strcmp(t->name, name) == 0) {
  			if (t->revision == revision) {
  				if (try_module_get(t->me)) {

  					mutex_unlock(&xt[af].mutex);

  					return t;
  				}
  			} else
  				err = -EPROTOTYPE; /* Found something. */
  		}
  	}

  	mutex_unlock(&xt[af].mutex);

  
  	if (af != NFPROTO_UNSPEC)
  		/* Try searching again in the family-independent list */
  		return xt_find_target(NFPROTO_UNSPEC, name, revision);

  	return ERR_PTR(err);
  }
  EXPORT_SYMBOL(xt_find_target);

  struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision)

  {
  	struct xt_target *target;

  	target = xt_find_target(af, name, revision);
  	if (IS_ERR(target)) {
  		request_module("%st_%s", xt_prefix[af], name);
  		target = xt_find_target(af, name, revision);
  	}
  
  	return target;

  }
  EXPORT_SYMBOL_GPL(xt_request_find_target);

  static int match_revfn(u8 af, const char *name, u8 revision, int *bestp)

  {

  	const struct xt_match *m;

  	int have_rev = 0;
  
  	list_for_each_entry(m, &xt[af].match, list) {
  		if (strcmp(m->name, name) == 0) {
  			if (m->revision > *bestp)
  				*bestp = m->revision;
  			if (m->revision == revision)
  				have_rev = 1;
  		}
  	}

  
  	if (af != NFPROTO_UNSPEC && !have_rev)
  		return match_revfn(NFPROTO_UNSPEC, name, revision, bestp);

  	return have_rev;
  }

  static int target_revfn(u8 af, const char *name, u8 revision, int *bestp)

  {

  	const struct xt_target *t;

  	int have_rev = 0;
  
  	list_for_each_entry(t, &xt[af].target, list) {
  		if (strcmp(t->name, name) == 0) {
  			if (t->revision > *bestp)
  				*bestp = t->revision;
  			if (t->revision == revision)
  				have_rev = 1;
  		}
  	}

  
  	if (af != NFPROTO_UNSPEC && !have_rev)
  		return target_revfn(NFPROTO_UNSPEC, name, revision, bestp);

  	return have_rev;
  }
  
  /* Returns true or false (if no such extension at all) */

  int xt_find_revision(u8 af, const char *name, u8 revision, int target,

  		     int *err)
  {
  	int have_rev, best = -1;

  	if (mutex_lock_interruptible(&xt[af].mutex) != 0) {

  		*err = -EINTR;
  		return 1;
  	}
  	if (target == 1)
  		have_rev = target_revfn(af, name, revision, &best);
  	else
  		have_rev = match_revfn(af, name, revision, &best);

  	mutex_unlock(&xt[af].mutex);

  
  	/* Nothing at all?  Return 0 to try loading module. */
  	if (best == -1) {
  		*err = -ENOENT;
  		return 0;
  	}
  
  	*err = best;
  	if (!have_rev)
  		*err = -EPROTONOSUPPORT;
  	return 1;
  }
  EXPORT_SYMBOL_GPL(xt_find_revision);

  static char *
  textify_hooks(char *buf, size_t size, unsigned int mask, uint8_t nfproto)

  {

  	static const char *const inetbr_names[] = {

  		"PREROUTING", "INPUT", "FORWARD",
  		"OUTPUT", "POSTROUTING", "BROUTING",
  	};

  	static const char *const arp_names[] = {
  		"INPUT", "FORWARD", "OUTPUT",
  	};
  	const char *const *names;
  	unsigned int i, max;

  	char *p = buf;
  	bool np = false;
  	int res;

  	names = (nfproto == NFPROTO_ARP) ? arp_names : inetbr_names;
  	max   = (nfproto == NFPROTO_ARP) ? ARRAY_SIZE(arp_names) :
  	                                   ARRAY_SIZE(inetbr_names);

  	*p = '\0';

  	for (i = 0; i < max; ++i) {

  		if (!(mask & (1 << i)))
  			continue;
  		res = snprintf(p, size, "%s%s", np ? "/" : "", names[i]);
  		if (res > 0) {
  			size -= res;
  			p += res;
  		}
  		np = true;
  	}
  
  	return buf;
  }

  int xt_check_match(struct xt_mtchk_param *par,

  		   unsigned int size, u_int8_t proto, bool inv_proto)

  {

  	int ret;

  	if (XT_ALIGN(par->match->matchsize) != size &&
  	    par->match->matchsize != -1) {

  		/*
  		 * ebt_among is exempt from centralized matchsize checking
  		 * because it uses a dynamic-size data set.
  		 */

  		pr_err("%s_tables: %s.%u match: invalid size "
  		       "%u (kernel) != (user) %u
  ",

  		       xt_prefix[par->family], par->match->name,

  		       par->match->revision,

  		       XT_ALIGN(par->match->matchsize), size);

  		return -EINVAL;
  	}

  	if (par->match->table != NULL &&
  	    strcmp(par->match->table, par->table) != 0) {

  		pr_err("%s_tables: %s match: only valid in %s table, not %s
  ",

  		       xt_prefix[par->family], par->match->name,

  		       par->match->table, par->table);

  		return -EINVAL;
  	}

  	if (par->match->hooks && (par->hook_mask & ~par->match->hooks) != 0) {

  		char used[64], allow[64];

  		pr_err("%s_tables: %s match: used from hooks %s, but only "

  		       "valid from %s
  ",

  		       xt_prefix[par->family], par->match->name,

  		       textify_hooks(used, sizeof(used), par->hook_mask,
  		                     par->family),
  		       textify_hooks(allow, sizeof(allow), par->match->hooks,
  		                     par->family));

  		return -EINVAL;
  	}

  	if (par->match->proto && (par->match->proto != proto || inv_proto)) {

  		pr_err("%s_tables: %s match: only valid for protocol %u
  ",

  		       xt_prefix[par->family], par->match->name,
  		       par->match->proto);

  		return -EINVAL;
  	}

  	if (par->match->checkentry != NULL) {
  		ret = par->match->checkentry(par);
  		if (ret < 0)
  			return ret;
  		else if (ret > 0)
  			/* Flag up potential errors. */
  			return -EIO;
  	}

  	return 0;
  }
  EXPORT_SYMBOL_GPL(xt_check_match);

  #ifdef CONFIG_COMPAT

  int xt_compat_add_offset(u_int8_t af, unsigned int offset, int delta)

  {

  	struct xt_af *xp = &xt[af];

  	if (!xp->compat_tab) {
  		if (!xp->number)
  			return -EINVAL;
  		xp->compat_tab = vmalloc(sizeof(struct compat_delta) * xp->number);
  		if (!xp->compat_tab)
  			return -ENOMEM;
  		xp->cur = 0;
  	}

  	if (xp->cur >= xp->number)
  		return -EINVAL;

  	if (xp->cur)
  		delta += xp->compat_tab[xp->cur - 1].delta;
  	xp->compat_tab[xp->cur].offset = offset;
  	xp->compat_tab[xp->cur].delta = delta;
  	xp->cur++;

  	return 0;
  }
  EXPORT_SYMBOL_GPL(xt_compat_add_offset);

  void xt_compat_flush_offsets(u_int8_t af)

  {

  	if (xt[af].compat_tab) {
  		vfree(xt[af].compat_tab);
  		xt[af].compat_tab = NULL;
  		xt[af].number = 0;

  		xt[af].cur = 0;

  	}
  }
  EXPORT_SYMBOL_GPL(xt_compat_flush_offsets);

  int xt_compat_calc_jump(u_int8_t af, unsigned int offset)

  {

  	struct compat_delta *tmp = xt[af].compat_tab;
  	int mid, left = 0, right = xt[af].cur - 1;
  
  	while (left <= right) {
  		mid = (left + right) >> 1;
  		if (offset > tmp[mid].offset)
  			left = mid + 1;
  		else if (offset < tmp[mid].offset)
  			right = mid - 1;
  		else
  			return mid ? tmp[mid - 1].delta : 0;
  	}

  	return left ? tmp[left - 1].delta : 0;

  }
  EXPORT_SYMBOL_GPL(xt_compat_calc_jump);

  void xt_compat_init_offsets(u_int8_t af, unsigned int number)
  {
  	xt[af].number = number;
  	xt[af].cur = 0;
  }
  EXPORT_SYMBOL(xt_compat_init_offsets);

  int xt_compat_match_offset(const struct xt_match *match)

  {

  	u_int16_t csize = match->compatsize ? : match->matchsize;
  	return XT_ALIGN(match->matchsize) - COMPAT_XT_ALIGN(csize);
  }
  EXPORT_SYMBOL_GPL(xt_compat_match_offset);

  int xt_compat_match_from_user(struct xt_entry_match *m, void **dstptr,

  			      unsigned int *size)

  {

  	const struct xt_match *match = m->u.kernel.match;

  	struct compat_xt_entry_match *cm = (struct compat_xt_entry_match *)m;
  	int pad, off = xt_compat_match_offset(match);
  	u_int16_t msize = cm->u.user.match_size;
  
  	m = *dstptr;
  	memcpy(m, cm, sizeof(*cm));
  	if (match->compat_from_user)
  		match->compat_from_user(m->data, cm->data);
  	else
  		memcpy(m->data, cm->data, msize - sizeof(*cm));
  	pad = XT_ALIGN(match->matchsize) - match->matchsize;
  	if (pad > 0)
  		memset(m->data + match->matchsize, 0, pad);
  
  	msize += off;
  	m->u.user.match_size = msize;
  
  	*size += off;
  	*dstptr += msize;

  	return 0;

  }
  EXPORT_SYMBOL_GPL(xt_compat_match_from_user);

  int xt_compat_match_to_user(const struct xt_entry_match *m,
  			    void __user **dstptr, unsigned int *size)

  {

  	const struct xt_match *match = m->u.kernel.match;

  	struct compat_xt_entry_match __user *cm = *dstptr;
  	int off = xt_compat_match_offset(match);
  	u_int16_t msize = m->u.user.match_size - off;
  
  	if (copy_to_user(cm, m, sizeof(*cm)) ||

  	    put_user(msize, &cm->u.user.match_size) ||
  	    copy_to_user(cm->u.user.name, m->u.kernel.match->name,
  			 strlen(m->u.kernel.match->name) + 1))

  		return -EFAULT;

  
  	if (match->compat_to_user) {
  		if (match->compat_to_user((void __user *)cm->data, m->data))
  			return -EFAULT;
  	} else {
  		if (copy_to_user(cm->data, m->data, msize - sizeof(*cm)))
  			return -EFAULT;

  	}

  
  	*size -= off;
  	*dstptr += msize;
  	return 0;

  }

  EXPORT_SYMBOL_GPL(xt_compat_match_to_user);
  #endif /* CONFIG_COMPAT */

  int xt_check_target(struct xt_tgchk_param *par,

  		    unsigned int size, u_int8_t proto, bool inv_proto)

  {

  	int ret;

  	if (XT_ALIGN(par->target->targetsize) != size) {

  		pr_err("%s_tables: %s.%u target: invalid size "
  		       "%u (kernel) != (user) %u
  ",

  		       xt_prefix[par->family], par->target->name,

  		       par->target->revision,

  		       XT_ALIGN(par->target->targetsize), size);

  		return -EINVAL;
  	}

  	if (par->target->table != NULL &&
  	    strcmp(par->target->table, par->table) != 0) {

  		pr_err("%s_tables: %s target: only valid in %s table, not %s
  ",

  		       xt_prefix[par->family], par->target->name,

  		       par->target->table, par->table);

  		return -EINVAL;
  	}

  	if (par->target->hooks && (par->hook_mask & ~par->target->hooks) != 0) {

  		char used[64], allow[64];

  		pr_err("%s_tables: %s target: used from hooks %s, but only "

  		       "usable from %s
  ",

  		       xt_prefix[par->family], par->target->name,

  		       textify_hooks(used, sizeof(used), par->hook_mask,
  		                     par->family),
  		       textify_hooks(allow, sizeof(allow), par->target->hooks,
  		                     par->family));

  		return -EINVAL;
  	}

  	if (par->target->proto && (par->target->proto != proto || inv_proto)) {

  		pr_err("%s_tables: %s target: only valid for protocol %u
  ",

  		       xt_prefix[par->family], par->target->name,

  		       par->target->proto);

  		return -EINVAL;
  	}

  	if (par->target->checkentry != NULL) {
  		ret = par->target->checkentry(par);
  		if (ret < 0)
  			return ret;
  		else if (ret > 0)
  			/* Flag up potential errors. */
  			return -EIO;
  	}

  	return 0;
  }
  EXPORT_SYMBOL_GPL(xt_check_target);

  #ifdef CONFIG_COMPAT

  int xt_compat_target_offset(const struct xt_target *target)

  {

  	u_int16_t csize = target->compatsize ? : target->targetsize;
  	return XT_ALIGN(target->targetsize) - COMPAT_XT_ALIGN(csize);
  }
  EXPORT_SYMBOL_GPL(xt_compat_target_offset);
  
  void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,

  				unsigned int *size)

  {

  	const struct xt_target *target = t->u.kernel.target;

  	struct compat_xt_entry_target *ct = (struct compat_xt_entry_target *)t;
  	int pad, off = xt_compat_target_offset(target);
  	u_int16_t tsize = ct->u.user.target_size;
  
  	t = *dstptr;
  	memcpy(t, ct, sizeof(*ct));
  	if (target->compat_from_user)
  		target->compat_from_user(t->data, ct->data);
  	else
  		memcpy(t->data, ct->data, tsize - sizeof(*ct));
  	pad = XT_ALIGN(target->targetsize) - target->targetsize;
  	if (pad > 0)
  		memset(t->data + target->targetsize, 0, pad);
  
  	tsize += off;
  	t->u.user.target_size = tsize;
  
  	*size += off;
  	*dstptr += tsize;
  }
  EXPORT_SYMBOL_GPL(xt_compat_target_from_user);

  int xt_compat_target_to_user(const struct xt_entry_target *t,
  			     void __user **dstptr, unsigned int *size)

  {

  	const struct xt_target *target = t->u.kernel.target;

  	struct compat_xt_entry_target __user *ct = *dstptr;
  	int off = xt_compat_target_offset(target);
  	u_int16_t tsize = t->u.user.target_size - off;
  
  	if (copy_to_user(ct, t, sizeof(*ct)) ||

  	    put_user(tsize, &ct->u.user.target_size) ||
  	    copy_to_user(ct->u.user.name, t->u.kernel.target->name,
  			 strlen(t->u.kernel.target->name) + 1))

  		return -EFAULT;

  
  	if (target->compat_to_user) {
  		if (target->compat_to_user((void __user *)ct->data, t->data))
  			return -EFAULT;
  	} else {
  		if (copy_to_user(ct->data, t->data, tsize - sizeof(*ct)))
  			return -EFAULT;

  	}

  
  	*size -= off;
  	*dstptr += tsize;
  	return 0;

  }

  EXPORT_SYMBOL_GPL(xt_compat_target_to_user);

  #endif

  struct xt_table_info *xt_alloc_table_info(unsigned int size)
  {
  	struct xt_table_info *newinfo;
  	int cpu;
  
  	/* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */

  	if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > totalram_pages)

  		return NULL;

  	newinfo = kzalloc(XT_TABLE_INFO_SZ, GFP_KERNEL);

  	if (!newinfo)
  		return NULL;
  
  	newinfo->size = size;

  	for_each_possible_cpu(cpu) {

  		if (size <= PAGE_SIZE)
  			newinfo->entries[cpu] = kmalloc_node(size,
  							GFP_KERNEL,
  							cpu_to_node(cpu));
  		else
  			newinfo->entries[cpu] = vmalloc_node(size,
  							cpu_to_node(cpu));
  
  		if (newinfo->entries[cpu] == NULL) {
  			xt_free_table_info(newinfo);
  			return NULL;
  		}
  	}
  
  	return newinfo;
  }
  EXPORT_SYMBOL(xt_alloc_table_info);
  
  void xt_free_table_info(struct xt_table_info *info)
  {
  	int cpu;

  	for_each_possible_cpu(cpu) {

  		if (info->size <= PAGE_SIZE)
  			kfree(info->entries[cpu]);
  		else
  			vfree(info->entries[cpu]);
  	}

  
  	if (info->jumpstack != NULL) {
  		if (sizeof(void *) * info->stacksize > PAGE_SIZE) {
  			for_each_possible_cpu(cpu)
  				vfree(info->jumpstack[cpu]);
  		} else {
  			for_each_possible_cpu(cpu)
  				kfree(info->jumpstack[cpu]);
  		}
  	}
  
  	if (sizeof(void **) * nr_cpu_ids > PAGE_SIZE)
  		vfree(info->jumpstack);
  	else
  		kfree(info->jumpstack);

  
  	free_percpu(info->stackptr);

  	kfree(info);
  }
  EXPORT_SYMBOL(xt_free_table_info);
  
  /* Find table by name, grabs mutex & ref.  Returns ERR_PTR() on error. */

  struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
  				    const char *name)

  {
  	struct xt_table *t;

  	if (mutex_lock_interruptible(&xt[af].mutex) != 0)

  		return ERR_PTR(-EINTR);

  	list_for_each_entry(t, &net->xt.tables[af], list)

  		if (strcmp(t->name, name) == 0 && try_module_get(t->me))
  			return t;

  	mutex_unlock(&xt[af].mutex);

  	return NULL;
  }
  EXPORT_SYMBOL_GPL(xt_find_table_lock);
  
  void xt_table_unlock(struct xt_table *table)
  {

  	mutex_unlock(&xt[table->af].mutex);

  }
  EXPORT_SYMBOL_GPL(xt_table_unlock);

  #ifdef CONFIG_COMPAT

  void xt_compat_lock(u_int8_t af)

  {
  	mutex_lock(&xt[af].compat_mutex);
  }
  EXPORT_SYMBOL_GPL(xt_compat_lock);

  void xt_compat_unlock(u_int8_t af)

  {
  	mutex_unlock(&xt[af].compat_mutex);
  }
  EXPORT_SYMBOL_GPL(xt_compat_unlock);
  #endif

  DEFINE_PER_CPU(seqcount_t, xt_recseq);
  EXPORT_PER_CPU_SYMBOL_GPL(xt_recseq);

  static int xt_jumpstack_alloc(struct xt_table_info *i)
  {
  	unsigned int size;
  	int cpu;

  	i->stackptr = alloc_percpu(unsigned int);

  	if (i->stackptr == NULL)
  		return -ENOMEM;

  
  	size = sizeof(void **) * nr_cpu_ids;
  	if (size > PAGE_SIZE)

  		i->jumpstack = vzalloc(size);

  	else

  		i->jumpstack = kzalloc(size, GFP_KERNEL);

  	if (i->jumpstack == NULL)
  		return -ENOMEM;

  
  	i->stacksize *= xt_jumpstack_multiplier;
  	size = sizeof(void *) * i->stacksize;
  	for_each_possible_cpu(cpu) {
  		if (size > PAGE_SIZE)
  			i->jumpstack[cpu] = vmalloc_node(size,
  				cpu_to_node(cpu));
  		else
  			i->jumpstack[cpu] = kmalloc_node(size,
  				GFP_KERNEL, cpu_to_node(cpu));
  		if (i->jumpstack[cpu] == NULL)
  			/*
  			 * Freeing will be done later on by the callers. The
  			 * chain is: xt_replace_table -> __do_replace ->
  			 * do_replace -> xt_free_table_info.
  			 */
  			return -ENOMEM;
  	}
  
  	return 0;
  }

  struct xt_table_info *
  xt_replace_table(struct xt_table *table,
  	      unsigned int num_counters,
  	      struct xt_table_info *newinfo,
  	      int *error)
  {

  	struct xt_table_info *private;

  	int ret;

  	ret = xt_jumpstack_alloc(newinfo);
  	if (ret < 0) {
  		*error = ret;
  		return NULL;
  	}

  	/* Do the substitution. */

  	local_bh_disable();

  	private = table->private;

  	/* Check inside lock: is the old number correct? */
  	if (num_counters != private->number) {

  		pr_debug("num_counters != table->private->number (%u/%u)
  ",

  			 num_counters, private->number);

  		local_bh_enable();

  		*error = -EAGAIN;
  		return NULL;
  	}

  	table->private = newinfo;
  	newinfo->initial_entries = private->initial_entries;
  
  	/*
  	 * Even though table entries have now been swapped, other CPU's
  	 * may still be using the old entries. This is okay, because
  	 * resynchronization happens because of the locking done
  	 * during the get_counters() routine.
  	 */
  	local_bh_enable();

  #ifdef CONFIG_AUDIT
  	if (audit_enabled) {
  		struct audit_buffer *ab;
  
  		ab = audit_log_start(current->audit_context, GFP_KERNEL,
  				     AUDIT_NETFILTER_CFG);
  		if (ab) {
  			audit_log_format(ab, "table=%s family=%u entries=%u",
  					 table->name, table->af,
  					 private->number);
  			audit_log_end(ab);
  		}
  	}
  #endif

  	return private;

  }
  EXPORT_SYMBOL_GPL(xt_replace_table);

  struct xt_table *xt_register_table(struct net *net,
  				   const struct xt_table *input_table,

  				   struct xt_table_info *bootstrap,
  				   struct xt_table_info *newinfo)

  {
  	int ret;
  	struct xt_table_info *private;

  	struct xt_table *t, *table;

  	/* Don't add one object to multiple lists. */

  	table = kmemdup(input_table, sizeof(struct xt_table), GFP_KERNEL);

  	if (!table) {
  		ret = -ENOMEM;
  		goto out;
  	}

  	ret = mutex_lock_interruptible(&xt[table->af].mutex);

  	if (ret != 0)

  		goto out_free;

  
  	/* Don't autoload: we'd eat our tail... */

  	list_for_each_entry(t, &net->xt.tables[table->af], list) {

  		if (strcmp(t->name, table->name) == 0) {
  			ret = -EEXIST;
  			goto unlock;
  		}

  	}
  
  	/* Simplifies replace_table code. */
  	table->private = bootstrap;

  	if (!xt_replace_table(table, 0, newinfo, &ret))
  		goto unlock;
  
  	private = table->private;

  	pr_debug("table->private->number = %u
  ", private->number);

  
  	/* save number of initial entries */
  	private->initial_entries = private->number;

  	list_add(&table->list, &net->xt.tables[table->af]);

  	mutex_unlock(&xt[table->af].mutex);
  	return table;

   unlock:

  	mutex_unlock(&xt[table->af].mutex);

  out_free:
  	kfree(table);

  out:
  	return ERR_PTR(ret);

  }
  EXPORT_SYMBOL_GPL(xt_register_table);
  
  void *xt_unregister_table(struct xt_table *table)
  {
  	struct xt_table_info *private;

  	mutex_lock(&xt[table->af].mutex);

  	private = table->private;

  	list_del(&table->list);

  	mutex_unlock(&xt[table->af].mutex);

  	kfree(table);

  
  	return private;
  }
  EXPORT_SYMBOL_GPL(xt_unregister_table);
  
  #ifdef CONFIG_PROC_FS

  struct xt_names_priv {
  	struct seq_net_private p;

  	u_int8_t af;

  };

  static void *xt_table_seq_start(struct seq_file *seq, loff_t *pos)

  {

  	struct xt_names_priv *priv = seq->private;

  	struct net *net = seq_file_net(seq);

  	u_int8_t af = priv->af;

  	mutex_lock(&xt[af].mutex);

  	return seq_list_start(&net->xt.tables[af], *pos);

  }

  static void *xt_table_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {

  	struct xt_names_priv *priv = seq->private;

  	struct net *net = seq_file_net(seq);

  	u_int8_t af = priv->af;

  	return seq_list_next(v, &net->xt.tables[af], pos);

  }

  static void xt_table_seq_stop(struct seq_file *seq, void *v)

  {

  	struct xt_names_priv *priv = seq->private;

  	u_int8_t af = priv->af;

  	mutex_unlock(&xt[af].mutex);
  }

  static int xt_table_seq_show(struct seq_file *seq, void *v)
  {
  	struct xt_table *table = list_entry(v, struct xt_table, list);

  	if (strlen(table->name))
  		return seq_printf(seq, "%s
  ", table->name);
  	else
  		return 0;
  }

  static const struct seq_operations xt_table_seq_ops = {
  	.start	= xt_table_seq_start,
  	.next	= xt_table_seq_next,
  	.stop	= xt_table_seq_stop,
  	.show	= xt_table_seq_show,
  };
  
  static int xt_table_open(struct inode *inode, struct file *file)
  {
  	int ret;

  	struct xt_names_priv *priv;

  	ret = seq_open_net(inode, file, &xt_table_seq_ops,
  			   sizeof(struct xt_names_priv));

  	if (!ret) {

  		priv = ((struct seq_file *)file->private_data)->private;

  		priv->af = (unsigned long)PDE_DATA(inode);

  	}
  	return ret;

  }

  static const struct file_operations xt_table_ops = {
  	.owner	 = THIS_MODULE,
  	.open	 = xt_table_open,
  	.read	 = seq_read,
  	.llseek	 = seq_lseek,

  	.release = seq_release_net,

  };

  /*
   * Traverse state for ip{,6}_{tables,matches} for helping crossing
   * the multi-AF mutexes.
   */
  struct nf_mttg_trav {
  	struct list_head *head, *curr;
  	uint8_t class, nfproto;
  };
  
  enum {
  	MTTG_TRAV_INIT,
  	MTTG_TRAV_NFP_UNSPEC,
  	MTTG_TRAV_NFP_SPEC,
  	MTTG_TRAV_DONE,
  };
  
  static void *xt_mttg_seq_next(struct seq_file *seq, void *v, loff_t *ppos,
      bool is_target)

  {

  	static const uint8_t next_class[] = {
  		[MTTG_TRAV_NFP_UNSPEC] = MTTG_TRAV_NFP_SPEC,
  		[MTTG_TRAV_NFP_SPEC]   = MTTG_TRAV_DONE,
  	};
  	struct nf_mttg_trav *trav = seq->private;
  
  	switch (trav->class) {
  	case MTTG_TRAV_INIT:
  		trav->class = MTTG_TRAV_NFP_UNSPEC;
  		mutex_lock(&xt[NFPROTO_UNSPEC].mutex);
  		trav->head = trav->curr = is_target ?
  			&xt[NFPROTO_UNSPEC].target : &xt[NFPROTO_UNSPEC].match;
   		break;
  	case MTTG_TRAV_NFP_UNSPEC:
  		trav->curr = trav->curr->next;
  		if (trav->curr != trav->head)
  			break;
  		mutex_unlock(&xt[NFPROTO_UNSPEC].mutex);
  		mutex_lock(&xt[trav->nfproto].mutex);
  		trav->head = trav->curr = is_target ?
  			&xt[trav->nfproto].target : &xt[trav->nfproto].match;
  		trav->class = next_class[trav->class];
  		break;
  	case MTTG_TRAV_NFP_SPEC:
  		trav->curr = trav->curr->next;
  		if (trav->curr != trav->head)
  			break;
  		/* fallthru, _stop will unlock */
  	default:
  		return NULL;
  	}

  	if (ppos != NULL)
  		++*ppos;
  	return trav;

  }

  static void *xt_mttg_seq_start(struct seq_file *seq, loff_t *pos,
      bool is_target)

  {

  	struct nf_mttg_trav *trav = seq->private;
  	unsigned int j;

  	trav->class = MTTG_TRAV_INIT;
  	for (j = 0; j < *pos; ++j)
  		if (xt_mttg_seq_next(seq, NULL, NULL, is_target) == NULL)
  			return NULL;
  	return trav;

  }

  static void xt_mttg_seq_stop(struct seq_file *seq, void *v)

  {

  	struct nf_mttg_trav *trav = seq->private;
  
  	switch (trav->class) {
  	case MTTG_TRAV_NFP_UNSPEC:
  		mutex_unlock(&xt[NFPROTO_UNSPEC].mutex);
  		break;
  	case MTTG_TRAV_NFP_SPEC:
  		mutex_unlock(&xt[trav->nfproto].mutex);
  		break;
  	}
  }

  static void *xt_match_seq_start(struct seq_file *seq, loff_t *pos)
  {
  	return xt_mttg_seq_start(seq, pos, false);

  }

  static void *xt_match_seq_next(struct seq_file *seq, void *v, loff_t *ppos)

  {

  	return xt_mttg_seq_next(seq, v, ppos, false);
  }

  static int xt_match_seq_show(struct seq_file *seq, void *v)
  {
  	const struct nf_mttg_trav *trav = seq->private;
  	const struct xt_match *match;
  
  	switch (trav->class) {
  	case MTTG_TRAV_NFP_UNSPEC:
  	case MTTG_TRAV_NFP_SPEC:
  		if (trav->curr == trav->head)
  			return 0;
  		match = list_entry(trav->curr, struct xt_match, list);
  		return (*match->name == '\0') ? 0 :
  		       seq_printf(seq, "%s
  ", match->name);
  	}
  	return 0;

  }

  static const struct seq_operations xt_match_seq_ops = {
  	.start	= xt_match_seq_start,
  	.next	= xt_match_seq_next,

  	.stop	= xt_mttg_seq_stop,

  	.show	= xt_match_seq_show,

  };

  static int xt_match_open(struct inode *inode, struct file *file)

  {

  	struct seq_file *seq;
  	struct nf_mttg_trav *trav;

  	int ret;

  	trav = kmalloc(sizeof(*trav), GFP_KERNEL);
  	if (trav == NULL)
  		return -ENOMEM;

  	ret = seq_open(file, &xt_match_seq_ops);
  	if (ret < 0) {
  		kfree(trav);
  		return ret;

  	}

  
  	seq = file->private_data;
  	seq->private = trav;

  	trav->nfproto = (unsigned long)PDE_DATA(inode);

  	return 0;

  }
  
  static const struct file_operations xt_match_ops = {
  	.owner	 = THIS_MODULE,
  	.open	 = xt_match_open,
  	.read	 = seq_read,
  	.llseek	 = seq_lseek,

  	.release = seq_release_private,

  };

  static void *xt_target_seq_start(struct seq_file *seq, loff_t *pos)
  {

  	return xt_mttg_seq_start(seq, pos, true);

  }

  static void *xt_target_seq_next(struct seq_file *seq, void *v, loff_t *ppos)

  {

  	return xt_mttg_seq_next(seq, v, ppos, true);

  }
  
  static int xt_target_seq_show(struct seq_file *seq, void *v)
  {

  	const struct nf_mttg_trav *trav = seq->private;
  	const struct xt_target *target;
  
  	switch (trav->class) {
  	case MTTG_TRAV_NFP_UNSPEC:
  	case MTTG_TRAV_NFP_SPEC:
  		if (trav->curr == trav->head)
  			return 0;
  		target = list_entry(trav->curr, struct xt_target, list);
  		return (*target->name == '\0') ? 0 :
  		       seq_printf(seq, "%s
  ", target->name);
  	}
  	return 0;

  }
  
  static const struct seq_operations xt_target_seq_ops = {
  	.start	= xt_target_seq_start,
  	.next	= xt_target_seq_next,

  	.stop	= xt_mttg_seq_stop,

  	.show	= xt_target_seq_show,
  };
  
  static int xt_target_open(struct inode *inode, struct file *file)
  {

  	struct seq_file *seq;
  	struct nf_mttg_trav *trav;

  	int ret;

  	trav = kmalloc(sizeof(*trav), GFP_KERNEL);
  	if (trav == NULL)
  		return -ENOMEM;

  	ret = seq_open(file, &xt_target_seq_ops);
  	if (ret < 0) {
  		kfree(trav);
  		return ret;

  	}

  
  	seq = file->private_data;
  	seq->private = trav;

  	trav->nfproto = (unsigned long)PDE_DATA(inode);

  	return 0;

  }

  static const struct file_operations xt_target_ops = {

  	.owner	 = THIS_MODULE,

  	.open	 = xt_target_open,

  	.read	 = seq_read,
  	.llseek	 = seq_lseek,

  	.release = seq_release_private,

  };
  
  #define FORMAT_TABLES	"_tables_names"
  #define	FORMAT_MATCHES	"_tables_matches"
  #define FORMAT_TARGETS 	"_tables_targets"
  
  #endif /* CONFIG_PROC_FS */

  /**
   * xt_hook_link - set up hooks for a new table
   * @table:	table with metadata needed to set up hooks
   * @fn:		Hook function
   *
   * This function will take care of creating and registering the necessary
   * Netfilter hooks for XT tables.
   */
  struct nf_hook_ops *xt_hook_link(const struct xt_table *table, nf_hookfn *fn)
  {
  	unsigned int hook_mask = table->valid_hooks;
  	uint8_t i, num_hooks = hweight32(hook_mask);
  	uint8_t hooknum;
  	struct nf_hook_ops *ops;
  	int ret;
  
  	ops = kmalloc(sizeof(*ops) * num_hooks, GFP_KERNEL);
  	if (ops == NULL)
  		return ERR_PTR(-ENOMEM);
  
  	for (i = 0, hooknum = 0; i < num_hooks && hook_mask != 0;
  	     hook_mask >>= 1, ++hooknum) {
  		if (!(hook_mask & 1))
  			continue;
  		ops[i].hook     = fn;
  		ops[i].owner    = table->me;
  		ops[i].pf       = table->af;
  		ops[i].hooknum  = hooknum;
  		ops[i].priority = table->priority;
  		++i;
  	}
  
  	ret = nf_register_hooks(ops, num_hooks);
  	if (ret < 0) {
  		kfree(ops);
  		return ERR_PTR(ret);
  	}
  
  	return ops;
  }
  EXPORT_SYMBOL_GPL(xt_hook_link);
  
  /**
   * xt_hook_unlink - remove hooks for a table
   * @ops:	nf_hook_ops array as returned by nf_hook_link
   * @hook_mask:	the very same mask that was passed to nf_hook_link
   */
  void xt_hook_unlink(const struct xt_table *table, struct nf_hook_ops *ops)
  {
  	nf_unregister_hooks(ops, hweight32(table->valid_hooks));
  	kfree(ops);
  }
  EXPORT_SYMBOL_GPL(xt_hook_unlink);

  int xt_proto_init(struct net *net, u_int8_t af)

  {
  #ifdef CONFIG_PROC_FS
  	char buf[XT_FUNCTION_MAXNAMELEN];
  	struct proc_dir_entry *proc;
  #endif

  	if (af >= ARRAY_SIZE(xt_prefix))

  		return -EINVAL;
  
  
  #ifdef CONFIG_PROC_FS

  	strlcpy(buf, xt_prefix[af], sizeof(buf));

  	strlcat(buf, FORMAT_TABLES, sizeof(buf));

  	proc = proc_create_data(buf, 0440, net->proc_net, &xt_table_ops,
  				(void *)(unsigned long)af);

  	if (!proc)
  		goto out;

  	strlcpy(buf, xt_prefix[af], sizeof(buf));

  	strlcat(buf, FORMAT_MATCHES, sizeof(buf));

  	proc = proc_create_data(buf, 0440, net->proc_net, &xt_match_ops,
  				(void *)(unsigned long)af);

  	if (!proc)
  		goto out_remove_tables;

  	strlcpy(buf, xt_prefix[af], sizeof(buf));

  	strlcat(buf, FORMAT_TARGETS, sizeof(buf));

  	proc = proc_create_data(buf, 0440, net->proc_net, &xt_target_ops,
  				(void *)(unsigned long)af);

  	if (!proc)
  		goto out_remove_matches;

  #endif
  
  	return 0;
  
  #ifdef CONFIG_PROC_FS
  out_remove_matches:

  	strlcpy(buf, xt_prefix[af], sizeof(buf));

  	strlcat(buf, FORMAT_MATCHES, sizeof(buf));

  	remove_proc_entry(buf, net->proc_net);

  
  out_remove_tables:

  	strlcpy(buf, xt_prefix[af], sizeof(buf));

  	strlcat(buf, FORMAT_TABLES, sizeof(buf));

  	remove_proc_entry(buf, net->proc_net);

  out:
  	return -1;
  #endif
  }
  EXPORT_SYMBOL_GPL(xt_proto_init);

  void xt_proto_fini(struct net *net, u_int8_t af)

  {
  #ifdef CONFIG_PROC_FS
  	char buf[XT_FUNCTION_MAXNAMELEN];

  	strlcpy(buf, xt_prefix[af], sizeof(buf));

  	strlcat(buf, FORMAT_TABLES, sizeof(buf));

  	remove_proc_entry(buf, net->proc_net);

  	strlcpy(buf, xt_prefix[af], sizeof(buf));

  	strlcat(buf, FORMAT_TARGETS, sizeof(buf));

  	remove_proc_entry(buf, net->proc_net);

  	strlcpy(buf, xt_prefix[af], sizeof(buf));

  	strlcat(buf, FORMAT_MATCHES, sizeof(buf));

  	remove_proc_entry(buf, net->proc_net);

  #endif /*CONFIG_PROC_FS*/
  }
  EXPORT_SYMBOL_GPL(xt_proto_fini);

  static int __net_init xt_net_init(struct net *net)
  {
  	int i;

  	for (i = 0; i < NFPROTO_NUMPROTO; i++)

  		INIT_LIST_HEAD(&net->xt.tables[i]);
  	return 0;
  }
  
  static struct pernet_operations xt_net_ops = {
  	.init = xt_net_init,
  };

  
  static int __init xt_init(void)
  {

  	unsigned int i;
  	int rv;
  
  	for_each_possible_cpu(i) {

  		seqcount_init(&per_cpu(xt_recseq, i));

  	}

  	xt = kmalloc(sizeof(struct xt_af) * NFPROTO_NUMPROTO, GFP_KERNEL);

  	if (!xt)
  		return -ENOMEM;

  	for (i = 0; i < NFPROTO_NUMPROTO; i++) {

  		mutex_init(&xt[i].mutex);

  #ifdef CONFIG_COMPAT
  		mutex_init(&xt[i].compat_mutex);

  		xt[i].compat_tab = NULL;

  #endif

  		INIT_LIST_HEAD(&xt[i].target);
  		INIT_LIST_HEAD(&xt[i].match);

  	}

  	rv = register_pernet_subsys(&xt_net_ops);
  	if (rv < 0)
  		kfree(xt);
  	return rv;

  }
  
  static void __exit xt_fini(void)
  {

  	unregister_pernet_subsys(&xt_net_ops);

  	kfree(xt);
  }
  
  module_init(xt_init);
  module_exit(xt_fini);