/* Copyright (C) 2000-2002 Joakim Axelsson <gozem@linux.nu>
 *                         Patrick Schaaf <bof@bof.de>
 * Copyright (C) 2003-2011 Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
 *
 * 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.
 */

/* Kernel module for IP set management */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/ip.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/netlink.h>
#include <linux/rculist.h>
#include <net/netlink.h>

#include <linux/netfilter.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/ipset/ip_set.h>

static LIST_HEAD(ip_set_type_list);		/* all registered set types */
static DEFINE_MUTEX(ip_set_type_mutex);		/* protects ip_set_type_list */
static DEFINE_RWLOCK(ip_set_ref_lock);		/* protects the set refs */

static struct ip_set **ip_set_list;		/* all individual sets */
static ip_set_id_t ip_set_max = CONFIG_IP_SET_MAX; /* max number of sets */

#define STREQ(a, b)	(strncmp(a, b, IPSET_MAXNAMELEN) == 0)

static unsigned int max_sets;

module_param(max_sets, int, 0600);
MODULE_PARM_DESC(max_sets, "maximal number of sets");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>");
MODULE_DESCRIPTION("core IP set support");
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_IPSET);

/*
 * The set types are implemented in modules and registered set types
 * can be found in ip_set_type_list. Adding/deleting types is
 * serialized by ip_set_type_mutex.
 */

static inline void
ip_set_type_lock(void)
{
	mutex_lock(&ip_set_type_mutex);
}

static inline void
ip_set_type_unlock(void)
{
	mutex_unlock(&ip_set_type_mutex);
}

/* Register and deregister settype */

static struct ip_set_type *
find_set_type(const char *name, u8 family, u8 revision)
{
	struct ip_set_type *type;

	list_for_each_entry_rcu(type, &ip_set_type_list, list)
		if (STREQ(type->name, name) &&
		    (type->family == family || type->family == NFPROTO_UNSPEC) &&
		    revision >= type->revision_min &&
		    revision <= type->revision_max)
			return type;
	return NULL;
}

/* Unlock, try to load a set type module and lock again */
static bool
load_settype(const char *name)
{
	nfnl_unlock();
	pr_debug("try to load ip_set_%s\n", name);
	if (request_module("ip_set_%s", name) < 0) {
		pr_warning("Can't find ip_set type %s\n", name);
		nfnl_lock();
		return false;
	}
	nfnl_lock();
	return true;
}

/* Find a set type and reference it */
#define find_set_type_get(name, family, revision, found)	\
	__find_set_type_get(name, family, revision, found, false)

static int
__find_set_type_get(const char *name, u8 family, u8 revision,
		    struct ip_set_type **found, bool retry)
{
	struct ip_set_type *type;
	int err;

	if (retry && !load_settype(name))
		return -IPSET_ERR_FIND_TYPE;

	rcu_read_lock();
	*found = find_set_type(name, family, revision);
	if (*found) {
		err = !try_module_get((*found)->me) ? -EFAULT : 0;
		goto unlock;
	}
	/* Make sure the type is already loaded
	 * but we don't support the revision */
	list_for_each_entry_rcu(type, &ip_set_type_list, list)
		if (STREQ(type->name, name)) {
			err = -IPSET_ERR_FIND_TYPE;
			goto unlock;
		}
	rcu_read_unlock();

	return retry ? -IPSET_ERR_FIND_TYPE :
		__find_set_type_get(name, family, revision, found, true);

unlock:
	rcu_read_unlock();
	return err;
}

/* Find a given set type by name and family.
 * If we succeeded, the supported minimal and maximum revisions are
 * filled out.
 */
#define find_set_type_minmax(name, family, min, max) \
	__find_set_type_minmax(name, family, min, max, false)

static int
__find_set_type_minmax(const char *name, u8 family, u8 *min, u8 *max,
		       bool retry)
{
	struct ip_set_type *type;
	bool found = false;

	if (retry && !load_settype(name))
		return -IPSET_ERR_FIND_TYPE;

	*min = 255; *max = 0;
	rcu_read_lock();
	list_for_each_entry_rcu(type, &ip_set_type_list, list)
		if (STREQ(type->name, name) &&
		    (type->family == family || type->family == NFPROTO_UNSPEC)) {
			found = true;
			if (type->revision_min < *min)
				*min = type->revision_min;
			if (type->revision_max > *max)
				*max = type->revision_max;
		}
	rcu_read_unlock();
	if (found)
		return 0;

	return retry ? -IPSET_ERR_FIND_TYPE :
		__find_set_type_minmax(name, family, min, max, true);
}

#define family_name(f)	((f) == NFPROTO_IPV4 ? "inet" : \
			 (f) == NFPROTO_IPV6 ? "inet6" : "any")

/* Register a set type structure. The type is identified by
 * the unique triple of name, family and revision.
 */
int
ip_set_type_register(struct ip_set_type *type)
{
	int ret = 0;

	if (type->protocol != IPSET_PROTOCOL) {
		pr_warning("ip_set type %s, family %s, revision %u:%u uses "
			   "wrong protocol version %u (want %u)\n",
			   type->name, family_name(type->family),
			   type->revision_min, type->revision_max,
			   type->protocol, IPSET_PROTOCOL);
		return -EINVAL;
	}

	ip_set_type_lock();
	if (find_set_type(type->name, type->family, type->revision_min)) {
		/* Duplicate! */
		pr_warning("ip_set type %s, family %s with revision min %u "
			   "already registered!\n", type->name,
			   family_name(type->family), type->revision_min);
		ret = -EINVAL;
		goto unlock;
	}
	list_add_rcu(&type->list, &ip_set_type_list);
	pr_debug("type %s, family %s, revision %u:%u registered.\n",
		 type->name, family_name(type->family),
		 type->revision_min, type->revision_max);
unlock:
	ip_set_type_unlock();
	return ret;
}
EXPORT_SYMBOL_GPL(ip_set_type_register);

/* Unregister a set type. There's a small race with ip_set_create */
void
ip_set_type_unregister(struct ip_set_type *type)
{
	ip_set_type_lock();
	if (!find_set_type(type->name, type->family, type->revision_min)) {
		pr_warning("ip_set type %s, family %s with revision min %u "
			   "not registered\n", type->name,
			   family_name(type->family), type->revision_min);
		goto unlock;
	}
	list_del_rcu(&type->list);
	pr_debug("type %s, family %s with revision min %u unregistered.\n",
		 type->name, family_name(type->family), type->revision_min);
unlock:
	ip_set_type_unlock();

	synchronize_rcu();
}
EXPORT_SYMBOL_GPL(ip_set_type_unregister);

/* Utility functions */
void *
ip_set_alloc(size_t size)
{
	void *members = NULL;

	if (size < KMALLOC_MAX_SIZE)
		members = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);

	if (members) {
		pr_debug("%p: allocated with kmalloc\n", members);
		return members;
	}

	members = vzalloc(size);
	if (!members)
		return NULL;
	pr_debug("%p: allocated with vmalloc\n", members);

	return members;
}
EXPORT_SYMBOL_GPL(ip_set_alloc);

void
ip_set_free(void *members)
{
	pr_debug("%p: free with %s\n", members,
		 is_vmalloc_addr(members) ? "vfree" : "kfree");
	if (is_vmalloc_addr(members))
		vfree(members);
	else
		kfree(members);
}
EXPORT_SYMBOL_GPL(ip_set_free);

static inline bool
flag_nested(const struct nlattr *nla)
{
	return nla->nla_type & NLA_F_NESTED;
}

static const struct nla_policy ipaddr_policy[IPSET_ATTR_IPADDR_MAX + 1] = {
	[IPSET_ATTR_IPADDR_IPV4]	= { .type = NLA_U32 },
	[IPSET_ATTR_IPADDR_IPV6]	= { .type = NLA_BINARY,
					    .len = sizeof(struct in6_addr) },
};

int
ip_set_get_ipaddr4(struct nlattr *nla,  __be32 *ipaddr)
{
	struct nlattr *tb[IPSET_ATTR_IPADDR_MAX+1];

	if (unlikely(!flag_nested(nla)))
		return -IPSET_ERR_PROTOCOL;
	if (nla_parse_nested(tb, IPSET_ATTR_IPADDR_MAX, nla, ipaddr_policy))
		return -IPSET_ERR_PROTOCOL;
	if (unlikely(!ip_set_attr_netorder(tb, IPSET_ATTR_IPADDR_IPV4)))
		return -IPSET_ERR_PROTOCOL;

	*ipaddr = nla_get_be32(tb[IPSET_ATTR_IPADDR_IPV4]);
	return 0;
}
EXPORT_SYMBOL_GPL(ip_set_get_ipaddr4);

int
ip_set_get_ipaddr6(struct nlattr *nla, union nf_inet_addr *ipaddr)
{
	struct nlattr *tb[IPSET_ATTR_IPADDR_MAX+1];

	if (unlikely(!flag_nested(nla)))
		return -IPSET_ERR_PROTOCOL;

	if (nla_parse_nested(tb, IPSET_ATTR_IPADDR_MAX, nla, ipaddr_policy))
		return -IPSET_ERR_PROTOCOL;
	if (unlikely(!ip_set_attr_netorder(tb, IPSET_ATTR_IPADDR_IPV6)))
		return -IPSET_ERR_PROTOCOL;

	memcpy(ipaddr, nla_data(tb[IPSET_ATTR_IPADDR_IPV6]),
		sizeof(struct in6_addr));
	return 0;
}
EXPORT_SYMBOL_GPL(ip_set_get_ipaddr6);

/*
 * Creating/destroying/renaming/swapping affect the existence and
 * the properties of a set. All of these can be executed from userspace
 * only and serialized by the nfnl mutex indirectly from nfnetlink.
 *
 * Sets are identified by their index in ip_set_list and the index
 * is used by the external references (set/SET netfilter modules).
 *
 * The set behind an index may change by swapping only, from userspace.
 */

static inline void
__ip_set_get(ip_set_id_t index)
{
	write_lock_bh(&ip_set_ref_lock);
	ip_set_list[index]->ref++;
	write_unlock_bh(&ip_set_ref_lock);
}

static inline void
__ip_set_put(ip_set_id_t index)
{
	write_lock_bh(&ip_set_ref_lock);
	BUG_ON(ip_set_list[index]->ref == 0);
	ip_set_list[index]->ref--;
	write_unlock_bh(&ip_set_ref_lock);
}

/*
 * Add, del and test set entries from kernel.
 *
 * The set behind the index must exist and must be referenced
 * so it can't be destroyed (or changed) under our foot.
 */

int
ip_set_test(ip_set_id_t index, const struct sk_buff *skb,
	    const struct xt_action_param *par,
	    const struct ip_set_adt_opt *opt)
{
	struct ip_set *set = ip_set_list[index];
	int ret = 0;

	BUG_ON(set == NULL);
	pr_debug("set %s, index %u\n", set->name, index);

	if (opt->dim < set->type->dimension ||
	    !(opt->family == set->family || set->family == NFPROTO_UNSPEC))
		return 0;

	read_lock_bh(&set->lock);
	ret = set->variant->kadt(set, skb, par, IPSET_TEST, opt);
	read_unlock_bh(&set->lock);

	if (ret == -EAGAIN) {
		/* Type requests element to be completed */
		pr_debug("element must be competed, ADD is triggered\n");
		write_lock_bh(&set->lock);
		set->variant->kadt(set, skb, par, IPSET_ADD, opt);
		write_unlock_bh(&set->lock);
		ret = 1;
	}

	/* Convert error codes to nomatch */
	return (ret < 0 ? 0 : ret);
}
EXPORT_SYMBOL_GPL(ip_set_test);

int
ip_set_add(ip_set_id_t index, const struct sk_buff *skb,
	   const struct xt_action_param *par,
	   const struct ip_set_adt_opt *opt)
{
	struct ip_set *set = ip_set_list[index];
	int ret;

	BUG_ON(set == NULL);
	pr_debug("set %s, index %u\n", set->name, index);

	if (opt->dim < set->type->dimension ||
	    !(opt->family == set->family || set->family == NFPROTO_UNSPEC))
		return 0;

	write_lock_bh(&set->lock);
	ret = set->variant->kadt(set, skb, par, IPSET_ADD, opt);
	write_unlock_bh(&set->lock);

	return ret;
}
EXPORT_SYMBOL_GPL(ip_set_add);

int
ip_set_del(ip_set_id_t index, const struct sk_buff *skb,
	   const struct xt_action_param *par,
	   const struct ip_set_adt_opt *opt)
{
	struct ip_set *set = ip_set_list[index];
	int ret = 0;

	BUG_ON(set == NULL);
	pr_debug("set %s, index %u\n", set->name, index);

	if (opt->dim < set->type->dimension ||
	    !(opt->family == set->family || set->family == NFPROTO_UNSPEC))
		return 0;

	write_lock_bh(&set->lock);
	ret = set->variant->kadt(set, skb, par, IPSET_DEL, opt);
	write_unlock_bh(&set->lock);

	return ret;
}
EXPORT_SYMBOL_GPL(ip_set_del);

/*
 * Find set by name, reference it once. The reference makes sure the
 * thing pointed to, does not go away under our feet.
 *
 */
ip_set_id_t
ip_set_get_byname(const char *name, struct ip_set **set)
{
	ip_set_id_t i, index = IPSET_INVALID_ID;
	struct ip_set *s;

	for (i = 0; i < ip_set_max; i++) {
		s = ip_set_list[i];
		if (s != NULL && STREQ(s->name, name)) {
			__ip_set_get(i);
			index = i;
			*set = s;
		}
	}

	return index;
}
EXPORT_SYMBOL_GPL(ip_set_get_byname);

/*
 * If the given set pointer points to a valid set, decrement
 * reference count by 1. The caller shall not assume the index
 * to be valid, after calling this function.
 *
 */
void
ip_set_put_byindex(ip_set_id_t index)
{
	if (ip_set_list[index] != NULL)
		__ip_set_put(index);
}
EXPORT_SYMBOL_GPL(ip_set_put_byindex);

/*
 * Get the name of a set behind a set index.
 * We assume the set is referenced, so it does exist and
 * can't be destroyed. The set cannot be renamed due to
 * the referencing either.
 *
 */
const char *
ip_set_name_byindex(ip_set_id_t index)
{
	const struct ip_set *set = ip_set_list[index];

	BUG_ON(set == NULL);
	BUG_ON(set->ref == 0);

	/* Referenced, so it's safe */
	return set->name;
}
EXPORT_SYMBOL_GPL(ip_set_name_byindex);

/*
 * Routines to call by external subsystems, which do not
 * call nfnl_lock for us.
 */

/*
 * Find set by name, reference it once. The reference makes sure the
 * thing pointed to, does not go away under our feet.
 *
 * The nfnl mutex is used in the function.
 */
ip_set_id_t
ip_set_nfnl_get(const char *name)
{
	struct ip_set *s;
	ip_set_id_t index;

	nfnl_lock();
	index = ip_set_get_byname(name, &s);
	nfnl_unlock();

	return index;
}
EXPORT_SYMBOL_GPL(ip_set_nfnl_get);

/*
 * Find set by index, reference it once. The reference makes sure the
 * thing pointed to, does not go away under our feet.
 *
 * The nfnl mutex is used in the function.
 */
ip_set_id_t
ip_set_nfnl_get_byindex(ip_set_id_t index)
{
	if (index > ip_set_max)
		return IPSET_INVALID_ID;

	nfnl_lock();
	if (ip_set_list[index])
		__ip_set_get(index);
	else
		index = IPSET_INVALID_ID;
	nfnl_unlock();

	return index;
}
EXPORT_SYMBOL_GPL(ip_set_nfnl_get_byindex);

/*
 * If the given set pointer points to a valid set, decrement
 * reference count by 1. The caller shall not assume the index
 * to be valid, after calling this function.
 *
 * The nfnl mutex is used in the function.
 */
void
ip_set_nfnl_put(ip_set_id_t index)
{
	nfnl_lock();
	ip_set_put_byindex(index);
	nfnl_unlock();
}
EXPORT_SYMBOL_GPL(ip_set_nfnl_put);

/*
 * Communication protocol with userspace over netlink.
 *
 * The commands are serialized by the nfnl mutex.
 */

static inline bool
protocol_failed(const struct nlattr * const tb[])
{
	return !tb[IPSET_ATTR_PROTOCOL] ||
	       nla_get_u8(tb[IPSET_ATTR_PROTOCOL]) != IPSET_PROTOCOL;
}

static inline u32
flag_exist(const struct nlmsghdr *nlh)
{
	return nlh->nlmsg_flags & NLM_F_EXCL ? 0 : IPSET_FLAG_EXIST;
}

static struct nlmsghdr *
start_msg(struct sk_buff *skb, u32 pid, u32 seq, unsigned int flags,
	  enum ipset_cmd cmd)
{
	struct nlmsghdr *nlh;
	struct nfgenmsg *nfmsg;

	nlh = nlmsg_put(skb, pid, seq, cmd | (NFNL_SUBSYS_IPSET << 8),
			sizeof(*nfmsg), flags);
	if (nlh == NULL)
		return NULL;

	nfmsg = nlmsg_data(nlh);
	nfmsg->nfgen_family = NFPROTO_IPV4;
	nfmsg->version = NFNETLINK_V0;
	nfmsg->res_id = 0;

	return nlh;
}

/* Create a set */

static const struct nla_policy ip_set_create_policy[IPSET_ATTR_CMD_MAX + 1] = {
	[IPSET_ATTR_PROTOCOL]	= { .type = NLA_U8 },
	[IPSET_ATTR_SETNAME]	= { .type = NLA_NUL_STRING,
				    .len = IPSET_MAXNAMELEN - 1 },
	[IPSET_ATTR_TYPENAME]	= { .type = NLA_NUL_STRING,
				    .len = IPSET_MAXNAMELEN - 1},
	[IPSET_ATTR_REVISION]	= { .type = NLA_U8 },
	[IPSET_ATTR_FAMILY]	= { .type = NLA_U8 },
	[IPSET_ATTR_DATA]	= { .type = NLA_NESTED },
};

static ip_set_id_t
find_set_id(const char *name)
{
	ip_set_id_t i, index = IPSET_INVALID_ID;
	const struct ip_set *set;

	for (i = 0; index == IPSET_INVALID_ID && i < ip_set_max; i++) {
		set = ip_set_list[i];
		if (set != NULL && STREQ(set->name, name))
			index = i;
	}
	return index;
}

static inline struct ip_set *
find_set(const char *name)
{
	ip_set_id_t index = find_set_id(name);

	return index == IPSET_INVALID_ID ? NULL : ip_set_list[index];
}

static int
find_free_id(const char *name, ip_set_id_t *index, struct ip_set **set)
{
	ip_set_id_t i;

	*index = IPSET_INVALID_ID;
	for (i = 0;  i < ip_set_max; i++) {
		if (ip_set_list[i] == NULL) {
			if (*index == IPSET_INVALID_ID)
				*index = i;
		} else if (STREQ(name, ip_set_list[i]->name)) {
			/* Name clash */
			*set = ip_set_list[i];
			return -EEXIST;
		}
	}
	if (*index == IPSET_INVALID_ID)
		/* No free slot remained */
		return -IPSET_ERR_MAX_SETS;
	return 0;
}

static int
ip_set_none(struct sock *ctnl, struct sk_buff *skb,
	    const struct nlmsghdr *nlh,
	    const struct nlattr * const attr[])
{
	return -EOPNOTSUPP;
}

static int
ip_set_create(struct sock *ctnl, struct sk_buff *skb,
	      const struct nlmsghdr *nlh,
	      const struct nlattr * const attr[])
{
	struct ip_set *set, *clash = NULL;
	ip_set_id_t index = IPSET_INVALID_ID;
	struct nlattr *tb[IPSET_ATTR_CREATE_MAX+1] = {};
	const char *name, *typename;
	u8 family, revision;
	u32 flags = flag_exist(nlh);
	int ret = 0;

	if (unlikely(protocol_failed(attr) ||
		     attr[IPSET_ATTR_SETNAME] == NULL ||
		     attr[IPSET_ATTR_TYPENAME] == NULL ||
		     attr[IPSET_ATTR_REVISION] == NULL ||
		     attr[IPSET_ATTR_FAMILY] == NULL ||
		     (attr[IPSET_ATTR_DATA] != NULL &&
		      !flag_nested(attr[IPSET_ATTR_DATA]))))
		return -IPSET_ERR_PROTOCOL;

	name = nla_data(attr[IPSET_ATTR_SETNAME]);
	typename = nla_data(attr[IPSET_ATTR_TYPENAME]);
	family = nla_get_u8(attr[IPSET_ATTR_FAMILY]);
	revision = nla_get_u8(attr[IPSET_ATTR_REVISION]);
	pr_debug("setname: %s, typename: %s, family: %s, revision: %u\n",
		 name, typename, family_name(family), revision);

	/*
	 * First, and without any locks, allocate and initialize
	 * a normal base set structure.
	 */
	set = kzalloc(sizeof(struct ip_set), GFP_KERNEL);
	if (!set)
		return -ENOMEM;
	rwlock_init(&set->lock);
	strlcpy(set->name, name, IPSET_MAXNAMELEN);
	set->family = family;
	set->revision = revision;

	/*
	 * Next, check that we know the type, and take
	 * a reference on the type, to make sure it stays available
	 * while constructing our new set.
	 *
	 * After referencing the type, we try to create the type
	 * specific part of the set without holding any locks.
	 */
	ret = find_set_type_get(typename, family, revision, &(set->type));
	if (ret)
		goto out;

	/*
	 * Without holding any locks, create private part.
	 */
	if (attr[IPSET_ATTR_DATA] &&
	    nla_parse_nested(tb, IPSET_ATTR_CREATE_MAX, attr[IPSET_ATTR_DATA],
			     set->type->create_policy)) {
		ret = -IPSET_ERR_PROTOCOL;
		goto put_out;
	}

	ret = set->type->create(set, tb, flags);
	if (ret != 0)
		goto put_out;

	/* BTW, ret==0 here. */

	/*
	 * Here, we have a valid, constructed set and we are protected
	 * by the nfnl mutex. Find the first free index in ip_set_list
	 * and check clashing.
	 */
	if ((ret = find_free_id(set->name, &index, &clash)) != 0) {
		/* If this is the same set and requested, ignore error */
		if (ret == -EEXIST &&
		    (flags & IPSET_FLAG_EXIST) &&
		    STREQ(set->type->name, clash->type->name) &&
		    set->type->family == clash->type->family &&
		    set->type->revision_min == clash->type->revision_min &&
		    set->type->revision_max == clash->type->revision_max &&
		    set->variant->same_set(set, clash))
			ret = 0;
		goto cleanup;
	}

	/*
	 * Finally! Add our shiny new set to the list, and be done.
	 */
	pr_debug("create: '%s' created with index %u!\n", set->name, index);
	ip_set_list[index] = set;

	return ret;

cleanup:
	set->variant->destroy(set);
put_out:
	module_put(set->type->me);
out:
	kfree(set);
	return ret;
}

/* Destroy sets */

static const struct nla_policy
ip_set_setname_policy[IPSET_ATTR_CMD_MAX + 1] = {
	[IPSET_ATTR_PROTOCOL]	= { .type = NLA_U8 },
	[IPSET_ATTR_SETNAME]	= { .type = NLA_NUL_STRING,
				    .len = IPSET_MAXNAMELEN - 1 },
};

static void
ip_set_destroy_set(ip_set_id_t index)
{
	struct ip_set *set = ip_set_list[index];

	pr_debug("set: %s\n",  set->name);
	ip_set_list[index] = NULL;

	/* Must call it without holding any lock */
	set->variant->destroy(set);
	module_put(set->type->me);
	kfree(set);
}

static int
ip_set_destroy(struct sock *ctnl, struct sk_buff *skb,
	       const struct nlmsghdr *nlh,
	       const struct nlattr * const attr[])
{
	ip_set_id_t i;
	int ret = 0;

	if (unlikely(protocol_failed(attr)))
		return -IPSET_ERR_PROTOCOL;

	/* Commands are serialized and references are
	 * protected by the ip_set_ref_lock.
	 * External systems (i.e. xt_set) must call
	 * ip_set_put|get_nfnl_* functions, that way we
	 * can safely check references here.
	 *
	 * list:set timer can only decrement the reference
	 * counter, so if it's already zero, we can proceed
	 * without holding the lock.
	 */
	read_lock_bh(&ip_set_ref_lock);
	if (!attr[IPSET_ATTR_SETNAME]) {
		for (i = 0; i < ip_set_max; i++) {
			if (ip_set_list[i] != NULL && ip_set_list[i]->ref) {
				ret = -IPSET_ERR_BUSY;
				goto out;
			}
		}
		read_unlock_bh(&ip_set_ref_lock);
		for (i = 0; i < ip_set_max; i++) {
			if (ip_set_list[i] != NULL)
				ip_set_destroy_set(i);
		}
	} else {
		i = find_set_id(nla_data(attr[IPSET_ATTR_SETNAME]));
		if (i == IPSET_INVALID_ID) {
			ret = -ENOENT;
			goto out;
		} else if (ip_set_list[i]->ref) {
			ret = -IPSET_ERR_BUSY;
			goto out;
		}
		read_unlock_bh(&ip_set_ref_lock);

		ip_set_destroy_set(i);
	}
	return 0;
out:
	read_unlock_bh(&ip_set_ref_lock);
	return ret;
}

/* Flush sets */

static void
ip_set_flush_set(struct ip_set *set)
{
	pr_debug("set: %s\n",  set->name);

	write_lock_bh(&set->lock);
	set->variant->flush(set);
	write_unlock_bh(&set->lock);
}

static int
ip_set_flush(struct sock *ctnl, struct sk_buff *skb,
	     const struct nlmsghdr *nlh,
	     const struct nlattr * const attr[])
{
	ip_set_id_t i;

	if (unlikely(protocol_failed(attr)))
		return -IPSET_ERR_PROTOCOL;

	if (!attr[IPSET_ATTR_SETNAME]) {
		for (i = 0; i < ip_set_max; i++)
			if (ip_set_list[i] != NULL)
				ip_set_flush_set(ip_set_list[i]);
	} else {
		i = find_set_id(nla_data(attr[IPSET_ATTR_SETNAME]));
		if (i == IPSET_INVALID_ID)
			return -ENOENT;

		ip_set_flush_set(ip_set_list[i]);
	}

	return 0;
}

/* Rename a set */

static const struct nla_policy
ip_set_setname2_policy[IPSET_ATTR_CMD_MAX + 1] = {
	[IPSET_ATTR_PROTOCOL]	= { .type = NLA_U8 },
	[IPSET_ATTR_SETNAME]	= { .type = NLA_NUL_STRING,
				    .len = IPSET_MAXNAMELEN - 1 },
	[IPSET_ATTR_SETNAME2]	= { .type = NLA_NUL_STRING,
				    .len = IPSET_MAXNAMELEN - 1 },
};

static int
ip_set_rename(struct sock *ctnl, struct sk_buff *skb,
	      const struct nlmsghdr *nlh,
	      const struct nlattr * const attr[])
{
	struct ip_set *set;
	const char *name2;
	ip_set_id_t i;
	int ret = 0;

	if (unlikely(protocol_failed(attr) ||
		     attr[IPSET_ATTR_SETNAME] == NULL ||
		     attr[IPSET_ATTR_SETNAME2] == NULL))
		return -IPSET_ERR_PROTOCOL;

	set = find_set(nla_data(attr[IPSET_ATTR_SETNAME]));
	if (set == NULL)
		return -ENOENT;

	read_lock_bh(&ip_set_ref_lock);
	if (set->ref != 0) {
		ret = -IPSET_ERR_REFERENCED;
		goto out;
	}

	name2 = nla_data(attr[IPSET_ATTR_SETNAME2]);
	for (i = 0; i < ip_set_max; i++) {
		if (ip_set_list[i] != NULL &&
		    STREQ(ip_set_list[i]->name, name2)) {
			ret = -IPSET_ERR_EXIST_SETNAME2;
			goto out;
		}
	}
	strncpy(set->name, name2, IPSET_MAXNAMELEN);

out:
	read_unlock_bh(&ip_set_ref_lock);
	return ret;
}

/* Swap two sets so that name/index points to the other.
 * References and set names are also swapped.
 *
 * The commands are serialized by the nfnl mutex and references are
 * protected by the ip_set_ref_lock. The kernel interfaces
 * do not hold the mutex but the pointer settings are atomic
 * so the ip_set_list always contains valid pointers to the sets.
 */

static int
ip_set_swap(struct sock *ctnl, struct sk_buff *skb,
	    const struct nlmsghdr *nlh,
	    const struct nlattr * const attr[])
{
	struct ip_set *from, *to;
	ip_set_id_t from_id, to_id;
	char from_name[IPSET_MAXNAMELEN];

	if (unlikely(protocol_failed(attr) ||
		     attr[IPSET_ATTR_SETNAME] == NULL ||
		     attr[IPSET_ATTR_SETNAME2] == NULL))
		return -IPSET_ERR_PROTOCOL;

	from_id = find_set_id(nla_data(attr[IPSET_ATTR_SETNAME]));
	if (from_id == IPSET_INVALID_ID)
		return -ENOENT;

	to_id = find_set_id(nla_data(attr[IPSET_ATTR_SETNAME2]));
	if (to_id == IPSET_INVALID_ID)
		return -IPSET_ERR_EXIST_SETNAME2;

	from = ip_set_list[from_id];
	to = ip_set_list[to_id];

	/* Features must not change.
	 * Not an artificial restriction anymore, as we must prevent
	 * possible loops created by swapping in setlist type of sets. */
	if (!(from->type->features == to->type->features &&
	      from->type->family == to->type->family))
		return -IPSET_ERR_TYPE_MISMATCH;

	strncpy(from_name, from->name, IPSET_MAXNAMELEN);
	strncpy(from->name, to->name, IPSET_MAXNAMELEN);
	strncpy(to->name, from_name, IPSET_MAXNAMELEN);

	write_lock_bh(&ip_set_ref_lock);
	swap(from->ref, to->ref);
	ip_set_list[from_id] = to;
	ip_set_list[to_id] = from;
	write_unlock_bh(&ip_set_ref_lock);

	return 0;
}

/* List/save set data */

#define DUMP_INIT	0
#define DUMP_ALL	1
#define DUMP_ONE	2
#define DUMP_LAST	3

#define DUMP_TYPE(arg)		(((u32)(arg)) & 0x0000FFFF)
#define DUMP_FLAGS(arg)		(((u32)(arg)) >> 16)

static int
ip_set_dump_done(struct netlink_callback *cb)
{
	if (cb->args[2]) {
		pr_debug("release set %s\n", ip_set_list[cb->args[1]]->name);
		ip_set_put_byindex((ip_set_id_t) cb->args[1]);
	}
	return 0;
}

static inline void
dump_attrs(struct nlmsghdr *nlh)
{
	const struct nlattr *attr;
	int rem;

	pr_debug("dump nlmsg\n");
	nlmsg_for_each_attr(attr, nlh, sizeof(struct nfgenmsg), rem) {
		pr_debug("type: %u, len %u\n", nla_type(attr), attr->nla_len);
	}
}

static int
dump_init(struct netlink_callback *cb)
{
	struct nlmsghdr *nlh = nlmsg_hdr(cb->skb);
	int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
	struct nlattr *cda[IPSET_ATTR_CMD_MAX+1];
	struct nlattr *attr = (void *)nlh + min_len;
	u32 dump_type;
	ip_set_id_t index;

	/* Second pass, so parser can't fail */
	nla_parse(cda, IPSET_ATTR_CMD_MAX,
		  attr, nlh->nlmsg_len - min_len, ip_set_setname_policy);

	/* cb->args[0] : dump single set/all sets
	 *         [1] : set index
	 *         [..]: type specific
	 */

	if (cda[IPSET_ATTR_SETNAME]) {
		index = find_set_id(nla_data(cda[IPSET_ATTR_SETNAME]));
		if (index == IPSET_INVALID_ID)
			return -ENOENT;

		dump_type = DUMP_ONE;
		cb->args[1] = index;
	} else
		dump_type = DUMP_ALL;

	if (cda[IPSET_ATTR_FLAGS]) {
		u32 f = ip_set_get_h32(cda[IPSET_ATTR_FLAGS]);
		dump_type |= (f << 16);
	}
	cb->args[0] = dump_type;

	return 0;
}

static int
ip_set_dump_start(struct sk_buff *skb, struct netlink_callback *cb)
{
	ip_set_id_t index = IPSET_INVALID_ID, max;
	struct ip_set *set = NULL;
	struct nlmsghdr *nlh = NULL;
	unsigned int flags = NETLINK_CB(cb->skb).pid ? NLM_F_MULTI : 0;
	u32 dump_type, dump_flags;
	int ret = 0;

	if (!cb->args[0]) {
		ret = dump_init(cb);
		if (ret < 0) {
			nlh = nlmsg_hdr(cb->skb);
			/* We have to create and send the error message
			 * manually :-( */
			if (nlh->nlmsg_flags & NLM_F_ACK)
				netlink_ack(cb->skb, nlh, ret);
			return ret;
		}
	}

	if (cb->args[1] >= ip_set_max)
		goto out;

	dump_type = DUMP_TYPE(cb->args[0]);
	dump_flags = DUMP_FLAGS(cb->args[0]);
	max = dump_type == DUMP_ONE ? cb->args[1] + 1 : ip_set_max;
dump_last:
	pr_debug("args[0]: %u %u args[1]: %ld\n",
		 dump_type, dump_flags, cb->args[1]);
	for (; cb->args[1] < max; cb->args[1]++) {
		index = (ip_set_id_t) cb->args[1];
		set = ip_set_list[index];
		if (set == NULL) {
			if (dump_type == DUMP_ONE) {
				ret = -ENOENT;
				goto out;
			}
			continue;
		}
		/* When dumping all sets, we must dump "sorted"
		 * so that lists (unions of sets) are dumped last.
		 */
		if (dump_type != DUMP_ONE &&
		    ((dump_type == DUMP_ALL) ==
		     !!(set->type->features & IPSET_DUMP_LAST)))
			continue;
		pr_debug("List set: %s\n", set->name);
		if (!cb->args[2]) {
			/* Start listing: make sure set won't be destroyed */
			pr_debug("reference set\n");
			__ip_set_get(index);
		}
		nlh = start_msg(skb, NETLINK_CB(cb->skb).pid,
				cb->nlh->nlmsg_seq, flags,
				IPSET_CMD_LIST);
		if (!nlh) {
			ret = -EMSGSIZE;
			goto release_refcount;
		}
		if (nla_put_u8(skb, IPSET_ATTR_PROTOCOL, IPSET_PROTOCOL) ||
		    nla_put_string(skb, IPSET_ATTR_SETNAME, set->name))
			goto nla_put_failure;
		if (dump_flags & IPSET_FLAG_LIST_SETNAME)
			goto next_set;
		switch (cb->args[2]) {
		case 0:
			/* Core header data */
			if (nla_put_string(skb, IPSET_ATTR_TYPENAME,
					   set->type->name) ||
			    nla_put_u8(skb, IPSET_ATTR_FAMILY,
				       set->family) ||
			    nla_put_u8(skb, IPSET_ATTR_REVISION,
				       set->revision))
				goto nla_put_failure;
			ret = set->variant->head(set, skb);
			if (ret < 0)
				goto release_refcount;
			if (dump_flags & IPSET_FLAG_LIST_HEADER)
				goto next_set;
			/* Fall through and add elements */
		default:
			read_lock_bh(&set->lock);
			ret = set->variant->list(set, skb, cb);
			read_unlock_bh(&set->lock);
			if (!cb->args[2])
				/* Set is done, proceed with next one */
				goto next_set;
			goto release_refcount;
		}
	}
	/* If we dump all sets, continue with dumping last ones */
	if (dump_type == DUMP_ALL) {
		dump_type = DUMP_LAST;
		cb->args[0] = dump_type | (dump_flags << 16);
		cb->args[1] = 0;
		goto dump_last;
	}
	goto out;

nla_put_failure:
	ret = -EFAULT;
next_set:
	if (dump_type == DUMP_ONE)
		cb->args[1] = IPSET_INVALID_ID;
	else
		cb->args[1]++;
release_refcount:
	/* If there was an error or set is done, release set */
	if (ret || !cb->args[2]) {
		pr_debug("release set %s\n", ip_set_list[index]->name);
		ip_set_put_byindex(index);
		cb->args[2] = 0;
	}
out:
	if (nlh) {
		nlmsg_end(skb, nlh);
		pr_debug("nlmsg_len: %u\n", nlh->nlmsg_len);
		dump_attrs(nlh);
	}

	return ret < 0 ? ret : skb->len;
}

static int
ip_set_dump(struct sock *ctnl, struct sk_buff *skb,
	    const struct nlmsghdr *nlh,
	    const struct nlattr * const attr[])
{
	if (unlikely(protocol_failed(attr)))
		return -IPSET_ERR_PROTOCOL;

	{
		struct netlink_dump_control c = {
			.dump = ip_set_dump_start,
			.done = ip_set_dump_done,
		};
		return netlink_dump_start(ctnl, skb, nlh, &c);
	}
}

/* Add, del and test */

static const struct nla_policy ip_set_adt_policy[IPSET_ATTR_CMD_MAX + 1] = {
	[IPSET_ATTR_PROTOCOL]	= { .type = NLA_U8 },
	[IPSET_ATTR_SETNAME]	= { .type = NLA_NUL_STRING,
				    .len = IPSET_MAXNAMELEN - 1 },
	[IPSET_ATTR_LINENO]	= { .type = NLA_U32 },
	[IPSET_ATTR_DATA]	= { .type = NLA_NESTED },
	[IPSET_ATTR_ADT]	= { .type = NLA_NESTED },
};

static int
call_ad(struct sock *ctnl, struct sk_buff *skb, struct ip_set *set,
	struct nlattr *tb[], enum ipset_adt adt,
	u32 flags, bool use_lineno)
{
	int ret;
	u32 lineno = 0;
	bool eexist = flags & IPSET_FLAG_EXIST, retried = false;

	do {
		write_lock_bh(&set->lock);
		ret = set->variant->uadt(set, tb, adt, &lineno, flags, retried);
		write_unlock_bh(&set->lock);
		retried = true;
	} while (ret == -EAGAIN &&
		 set->variant->resize &&
		 (ret = set->variant->resize(set, retried)) == 0);

	if (!ret || (ret == -IPSET_ERR_EXIST && eexist))
		return 0;
	if (lineno && use_lineno) {
		/* Error in restore/batch mode: send back lineno */
		struct nlmsghdr *rep, *nlh = nlmsg_hdr(skb);
		struct sk_buff *skb2;
		struct nlmsgerr *errmsg;
		size_t payload = sizeof(*errmsg) + nlmsg_len(nlh);
		int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
		struct nlattr *cda[IPSET_ATTR_CMD_MAX+1];
		struct nlattr *cmdattr;
		u32 *errline;

		skb2 = nlmsg_new(payload, GFP_KERNEL);
		if (skb2 == NULL)
			return -ENOMEM;
		rep = __nlmsg_put(skb2, NETLINK_CB(skb).pid,
				  nlh->nlmsg_seq, NLMSG_ERROR, payload, 0);
		errmsg = nlmsg_data(rep);
		errmsg->error = ret;
		memcpy(&errmsg->msg, nlh, nlh->nlmsg_len);
		cmdattr = (void *)&errmsg->msg + min_len;

		nla_parse(cda, IPSET_ATTR_CMD_MAX,
			  cmdattr, nlh->nlmsg_len - min_len,
			  ip_set_adt_policy);

		errline = nla_data(cda[IPSET_ATTR_LINENO]);

		*errline = lineno;

		netlink_unicast(ctnl, skb2, NETLINK_CB(skb).pid, MSG_DONTWAIT);
		/* Signal netlink not to send its ACK/errmsg.  */
		return -EINTR;
	}

	return ret;
}

static int
ip_set_uadd(struct sock *ctnl, struct sk_buff *skb,
	    const struct nlmsghdr *nlh,
	    const struct nlattr * const attr[])
{
	struct ip_set *set;
	struct nlattr *tb[IPSET_ATTR_ADT_MAX+1] = {};
	const struct nlattr *nla;
	u32 flags = flag_exist(nlh);
	bool use_lineno;
	int ret = 0;

	if (unlikely(protocol_failed(attr) ||
		     attr[IPSET_ATTR_SETNAME] == NULL ||
		     !((attr[IPSET_ATTR_DATA] != NULL) ^
		       (attr[IPSET_ATTR_ADT] != NULL)) ||
		     (attr[IPSET_ATTR_DATA] != NULL &&
		      !flag_nested(attr[IPSET_ATTR_DATA])) ||
		     (attr[IPSET_ATTR_ADT] != NULL &&
		      (!flag_nested(attr[IPSET_ATTR_ADT]) ||
		       attr[IPSET_ATTR_LINENO] == NULL))))
		return -IPSET_ERR_PROTOCOL;

	set = find_set(nla_data(attr[IPSET_ATTR_SETNAME]));
	if (set == NULL)
		return -ENOENT;

	use_lineno = !!attr[IPSET_ATTR_LINENO];
	if (attr[IPSET_ATTR_DATA]) {
		if (nla_parse_nested(tb, IPSET_ATTR_ADT_MAX,
				     attr[IPSET_ATTR_DATA],
				     set->type->adt_policy))
			return -IPSET_ERR_PROTOCOL;
		ret = call_ad(ctnl, skb, set, tb, IPSET_ADD, flags,
			      use_lineno);
	} else {
		int nla_rem;

		nla_for_each_nested(nla, attr[IPSET_ATTR_ADT], nla_rem) {
			memset(tb, 0, sizeof(tb));
			if (nla_type(nla) != IPSET_ATTR_DATA ||
			    !flag_nested(nla) ||
			    nla_parse_nested(tb, IPSET_ATTR_ADT_MAX, nla,
					     set->type->adt_policy))
				return -IPSET_ERR_PROTOCOL;
			ret = call_ad(ctnl, skb, set, tb, IPSET_ADD,
				      flags, use_lineno);
			if (ret < 0)
				return ret;
		}
	}
	return ret;
}

static int
ip_set_udel(struct sock *ctnl, struct sk_buff *skb,
	    const struct nlmsghdr *nlh,
	    const struct nlattr * const attr[])
{
	struct ip_set *set;
	struct nlattr *tb[IPSET_ATTR_ADT_MAX+1] = {};
	const struct nlattr *nla;
	u32 flags = flag_exist(nlh);
	bool use_lineno;
	int ret = 0;

	if (unlikely(protocol_failed(attr) ||
		     attr[IPSET_ATTR_SETNAME] == NULL ||
		     !((attr[IPSET_ATTR_DATA] != NULL) ^
		       (attr[IPSET_ATTR_ADT] != NULL)) ||
		     (attr[IPSET_ATTR_DATA] != NULL &&
		      !flag_nested(attr[IPSET_ATTR_DATA])) ||
		     (attr[IPSET_ATTR_ADT] != NULL &&
		      (!flag_nested(attr[IPSET_ATTR_ADT]) ||
		       attr[IPSET_ATTR_LINENO] == NULL))))
		return -IPSET_ERR_PROTOCOL;

	set = find_set(nla_data(attr[IPSET_ATTR_SETNAME]));
	if (set == NULL)
		return -ENOENT;

	use_lineno = !!attr[IPSET_ATTR_LINENO];
	if (attr[IPSET_ATTR_DATA]) {
		if (nla_parse_nested(tb, IPSET_ATTR_ADT_MAX,
				     attr[IPSET_ATTR_DATA],
				     set->type->adt_policy))
			return -IPSET_ERR_PROTOCOL;
		ret = call_ad(ctnl, skb, set, tb, IPSET_DEL, flags,
			      use_lineno);
	} else {
		int nla_rem;

		nla_for_each_nested(nla, attr[IPSET_ATTR_ADT], nla_rem) {
			memset(tb, 0, sizeof(*tb));
			if (nla_type(nla) != IPSET_ATTR_DATA ||
			    !flag_nested(nla) ||
			    nla_parse_nested(tb, IPSET_ATTR_ADT_MAX, nla,
					     set->type->adt_policy))
				return -IPSET_ERR_PROTOCOL;
			ret = call_ad(ctnl, skb, set, tb, IPSET_DEL,
				      flags, use_lineno);
			if (ret < 0)
				return ret;
		}
	}
	return ret;
}

static int
ip_set_utest(struct sock *ctnl, struct sk_buff *skb,
	     const struct nlmsghdr *nlh,
	     const struct nlattr * const attr[])
{
	struct ip_set *set;
	struct nlattr *tb[IPSET_ATTR_ADT_MAX+1] = {};
	int ret = 0;

	if (unlikely(protocol_failed(attr) ||
		     attr[IPSET_ATTR_SETNAME] == NULL ||
		     attr[IPSET_ATTR_DATA] == NULL ||
		     !flag_nested(attr[IPSET_ATTR_DATA])))
		return -IPSET_ERR_PROTOCOL;

	set = find_set(nla_data(attr[IPSET_ATTR_SETNAME]));
	if (set == NULL)
		return -ENOENT;

	if (nla_parse_nested(tb, IPSET_ATTR_ADT_MAX, attr[IPSET_ATTR_DATA],
			     set->type->adt_policy))
		return -IPSET_ERR_PROTOCOL;

	read_lock_bh(&set->lock);
	ret = set->variant->uadt(set, tb, IPSET_TEST, NULL, 0, 0);
	read_unlock_bh(&set->lock);
	/* Userspace can't trigger element to be re-added */
	if (ret == -EAGAIN)
		ret = 1;

	return ret < 0 ? ret : ret > 0 ? 0 : -IPSET_ERR_EXIST;
}

/* Get headed data of a set */

static int
ip_set_header(struct sock *ctnl, struct sk_buff *skb,
	      const struct nlmsghdr *nlh,
	      const struct nlattr * const attr[])
{
	const struct ip_set *set;
	struct sk_buff *skb2;
	struct nlmsghdr *nlh2;
	ip_set_id_t index;
	int ret = 0;

	if (unlikely(protocol_failed(attr) ||
		     attr[IPSET_ATTR_SETNAME] == NULL))
		return -IPSET_ERR_PROTOCOL;

	index = find_set_id(nla_data(attr[IPSET_ATTR_SETNAME]));
	if (index == IPSET_INVALID_ID)
		return -ENOENT;
	set = ip_set_list[index];

	skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
	if (skb2 == NULL)
		return -ENOMEM;

	nlh2 = start_msg(skb2, NETLINK_CB(skb).pid, nlh->nlmsg_seq, 0,
			 IPSET_CMD_HEADER);
	if (!nlh2)
		goto nlmsg_failure;
	if (nla_put_u8(skb2, IPSET_ATTR_PROTOCOL, IPSET_PROTOCOL) ||
	    nla_put_string(skb2, IPSET_ATTR_SETNAME, set->name) ||
	    nla_put_string(skb2, IPSET_ATTR_TYPENAME, set->type->name) ||
	    nla_put_u8(skb2, IPSET_ATTR_FAMILY, set->family) ||
	    nla_put_u8(skb2, IPSET_ATTR_REVISION, set->revision))
		goto nla_put_failure;
	nlmsg_end(skb2, nlh2);

	ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).pid, MSG_DONTWAIT);
	if (ret < 0)
		return ret;

	return 0;

nla_put_failure:
	nlmsg_cancel(skb2, nlh2);
nlmsg_failure:
	kfree_skb(skb2);
	return -EMSGSIZE;
}

/* Get type data */

static const struct nla_policy ip_set_type_policy[IPSET_ATTR_CMD_MAX + 1] = {
	[IPSET_ATTR_PROTOCOL]	= { .type = NLA_U8 },
	[IPSET_ATTR_TYPENAME]	= { .type = NLA_NUL_STRING,
				    .len = IPSET_MAXNAMELEN - 1 },
	[IPSET_ATTR_FAMILY]	= { .type = NLA_U8 },
};

static int
ip_set_type(struct sock *ctnl, struct sk_buff *skb,
	    const struct nlmsghdr *nlh,
	    const struct nlattr * const attr[])
{
	struct sk_buff *skb2;
	struct nlmsghdr *nlh2;
	u8 family, min, max;
	const char *typename;
	int ret = 0;

	if (unlikely(protocol_failed(attr) ||
		     attr[IPSET_ATTR_TYPENAME] == NULL ||
		     attr[IPSET_ATTR_FAMILY] == NULL))
		return -IPSET_ERR_PROTOCOL;

	family = nla_get_u8(attr[IPSET_ATTR_FAMILY]);
	typename = nla_data(attr[IPSET_ATTR_TYPENAME]);
	ret = find_set_type_minmax(typename, family, &min, &max);
	if (ret)
		return ret;

	skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
	if (skb2 == NULL)
		return -ENOMEM;

	nlh2 = start_msg(skb2, NETLINK_CB(skb).pid, nlh->nlmsg_seq, 0,
			 IPSET_CMD_TYPE);
	if (!nlh2)
		goto nlmsg_failure;
	if (nla_put_u8(skb2, IPSET_ATTR_PROTOCOL, IPSET_PROTOCOL) ||
	    nla_put_string(skb2, IPSET_ATTR_TYPENAME, typename) ||
	    nla_put_u8(skb2, IPSET_ATTR_FAMILY, family) ||
	    nla_put_u8(skb2, IPSET_ATTR_REVISION, max) ||
	    nla_put_u8(skb2, IPSET_ATTR_REVISION_MIN, min))
		goto nla_put_failure;
	nlmsg_end(skb2, nlh2);

	pr_debug("Send TYPE, nlmsg_len: %u\n", nlh2->nlmsg_len);
	ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).pid, MSG_DONTWAIT);
	if (ret < 0)
		return ret;

	return 0;

nla_put_failure:
	nlmsg_cancel(skb2, nlh2);
nlmsg_failure:
	kfree_skb(skb2);
	return -EMSGSIZE;
}

/* Get protocol version */

static const struct nla_policy
ip_set_protocol_policy[IPSET_ATTR_CMD_MAX + 1] = {
	[IPSET_ATTR_PROTOCOL]	= { .type = NLA_U8 },
};

static int
ip_set_protocol(struct sock *ctnl, struct sk_buff *skb,
		const struct nlmsghdr *nlh,
		const struct nlattr * const attr[])
{
	struct sk_buff *skb2;
	struct nlmsghdr *nlh2;
	int ret = 0;

	if (unlikely(attr[IPSET_ATTR_PROTOCOL] == NULL))
		return -IPSET_ERR_PROTOCOL;

	skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
	if (skb2 == NULL)
		return -ENOMEM;

	nlh2 = start_msg(skb2, NETLINK_CB(skb).pid, nlh->nlmsg_seq, 0,
			 IPSET_CMD_PROTOCOL);
	if (!nlh2)
		goto nlmsg_failure;
	if (nla_put_u8(skb2, IPSET_ATTR_PROTOCOL, IPSET_PROTOCOL))
		goto nla_put_failure;
	nlmsg_end(skb2, nlh2);

	ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).pid, MSG_DONTWAIT);
	if (ret < 0)
		return ret;

	return 0;

nla_put_failure:
	nlmsg_cancel(skb2, nlh2);
nlmsg_failure:
	kfree_skb(skb2);
	return -EMSGSIZE;
}

static const struct nfnl_callback ip_set_netlink_subsys_cb[IPSET_MSG_MAX] = {
	[IPSET_CMD_NONE]	= {
		.call		= ip_set_none,
		.attr_count	= IPSET_ATTR_CMD_MAX,
	},
	[IPSET_CMD_CREATE]	= {
		.call		= ip_set_create,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_create_policy,
	},
	[IPSET_CMD_DESTROY]	= {
		.call		= ip_set_destroy,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_setname_policy,
	},
	[IPSET_CMD_FLUSH]	= {
		.call		= ip_set_flush,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_setname_policy,
	},
	[IPSET_CMD_RENAME]	= {
		.call		= ip_set_rename,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_setname2_policy,
	},
	[IPSET_CMD_SWAP]	= {
		.call		= ip_set_swap,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_setname2_policy,
	},
	[IPSET_CMD_LIST]	= {
		.call		= ip_set_dump,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_setname_policy,
	},
	[IPSET_CMD_SAVE]	= {
		.call		= ip_set_dump,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_setname_policy,
	},
	[IPSET_CMD_ADD]	= {
		.call		= ip_set_uadd,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_adt_policy,
	},
	[IPSET_CMD_DEL]	= {
		.call		= ip_set_udel,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_adt_policy,
	},
	[IPSET_CMD_TEST]	= {
		.call		= ip_set_utest,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_adt_policy,
	},
	[IPSET_CMD_HEADER]	= {
		.call		= ip_set_header,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_setname_policy,
	},
	[IPSET_CMD_TYPE]	= {
		.call		= ip_set_type,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_type_policy,
	},
	[IPSET_CMD_PROTOCOL]	= {
		.call		= ip_set_protocol,
		.attr_count	= IPSET_ATTR_CMD_MAX,
		.policy		= ip_set_protocol_policy,
	},
};

static struct nfnetlink_subsystem ip_set_netlink_subsys __read_mostly = {
	.name		= "ip_set",
	.subsys_id	= NFNL_SUBSYS_IPSET,
	.cb_count	= IPSET_MSG_MAX,
	.cb		= ip_set_netlink_subsys_cb,
};

/* Interface to iptables/ip6tables */

static int
ip_set_sockfn_get(struct sock *sk, int optval, void __user *user, int *len)
{
	unsigned int *op;
	void *data;
	int copylen = *len, ret = 0;

	if (!capable(CAP_NET_ADMIN))
		return -EPERM;
	if (optval != SO_IP_SET)
		return -EBADF;
	if (*len < sizeof(unsigned int))
		return -EINVAL;

	data = vmalloc(*len);
	if (!data)
		return -ENOMEM;
	if (copy_from_user(data, user, *len) != 0) {
		ret = -EFAULT;
		goto done;
	}
	op = (unsigned int *) data;

	if (*op < IP_SET_OP_VERSION) {
		/* Check the version at the beginning of operations */
		struct ip_set_req_version *req_version = data;
		if (req_version->version != IPSET_PROTOCOL) {
			ret = -EPROTO;
			goto done;
		}
	}

	switch (*op) {
	case IP_SET_OP_VERSION: {
		struct ip_set_req_version *req_version = data;

		if (*len != sizeof(struct ip_set_req_version)) {
			ret = -EINVAL;
			goto done;
		}

		req_version->version = IPSET_PROTOCOL;
		ret = copy_to_user(user, req_version,
				   sizeof(struct ip_set_req_version));
		goto done;
	}
	case IP_SET_OP_GET_BYNAME: {
		struct ip_set_req_get_set *req_get = data;

		if (*len != sizeof(struct ip_set_req_get_set)) {
			ret = -EINVAL;
			goto done;
		}
		req_get->set.name[IPSET_MAXNAMELEN - 1] = '\0';
		nfnl_lock();
		req_get->set.index = find_set_id(req_get->set.name);
		nfnl_unlock();
		goto copy;
	}
	case IP_SET_OP_GET_BYINDEX: {
		struct ip_set_req_get_set *req_get = data;

		if (*len != sizeof(struct ip_set_req_get_set) ||
		    req_get->set.index >= ip_set_max) {
			ret = -EINVAL;
			goto done;
		}
		nfnl_lock();
		strncpy(req_get->set.name,
			ip_set_list[req_get->set.index]
				? ip_set_list[req_get->set.index]->name : "",
			IPSET_MAXNAMELEN);
		nfnl_unlock();
		goto copy;
	}
	default:
		ret = -EBADMSG;
		goto done;
	}	/* end of switch(op) */

copy:
	ret = copy_to_user(user, data, copylen);

done:
	vfree(data);
	if (ret > 0)
		ret = 0;
	return ret;
}

static struct nf_sockopt_ops so_set __read_mostly = {
	.pf		= PF_INET,
	.get_optmin	= SO_IP_SET,
	.get_optmax	= SO_IP_SET + 1,
	.get		= &ip_set_sockfn_get,
	.owner		= THIS_MODULE,
};

static int __init
ip_set_init(void)
{
	int ret;

	if (max_sets)
		ip_set_max = max_sets;
	if (ip_set_max >= IPSET_INVALID_ID)
		ip_set_max = IPSET_INVALID_ID - 1;

	ip_set_list = kzalloc(sizeof(struct ip_set *) * ip_set_max,
			      GFP_KERNEL);
	if (!ip_set_list)
		return -ENOMEM;

	ret = nfnetlink_subsys_register(&ip_set_netlink_subsys);
	if (ret != 0) {
		pr_err("ip_set: cannot register with nfnetlink.\n");
		kfree(ip_set_list);
		return ret;
	}
	ret = nf_register_sockopt(&so_set);
	if (ret != 0) {
		pr_err("SO_SET registry failed: %d\n", ret);
		nfnetlink_subsys_unregister(&ip_set_netlink_subsys);
		kfree(ip_set_list);
		return ret;
	}

	pr_notice("ip_set: protocol %u\n", IPSET_PROTOCOL);
	return 0;
}

static void __exit
ip_set_fini(void)
{
	/* There can't be any existing set */
	nf_unregister_sockopt(&so_set);
	nfnetlink_subsys_unregister(&ip_set_netlink_subsys);
	kfree(ip_set_list);
	pr_debug("these are the famous last words\n");
}

module_init(ip_set_init);
module_exit(ip_set_fini);