[mirror_ubuntu-bionic-kernel.git] / net / netfilter / xt_statistic.c

/*
 * Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
 *
 * 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.
 *
 * Based on ipt_random and ipt_nth by Fabrice MARIE <fabrice@netfilter.org>.
 */

#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/net.h>

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

struct xt_statistic_priv {
	uint32_t count;
};

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)");
MODULE_ALIAS("ipt_statistic");
MODULE_ALIAS("ip6t_statistic");

static DEFINE_SPINLOCK(nth_lock);

static bool
statistic_mt(const struct sk_buff *skb, const struct xt_match_param *par)
{
	const struct xt_statistic_info *info = par->matchinfo;
	bool ret = info->flags & XT_STATISTIC_INVERT;

	switch (info->mode) {
	case XT_STATISTIC_MODE_RANDOM:
		if ((net_random() & 0x7FFFFFFF) < info->u.random.probability)
			ret = !ret;
		break;
	case XT_STATISTIC_MODE_NTH:
		spin_lock_bh(&nth_lock);
		if (info->master->count++ == info->u.nth.every) {
			info->master->count = 0;
			ret = !ret;
		}
		spin_unlock_bh(&nth_lock);
		break;
	}

	return ret;
}

static bool statistic_mt_check(const struct xt_mtchk_param *par)
{
	struct xt_statistic_info *info = par->matchinfo;

	if (info->mode > XT_STATISTIC_MODE_MAX ||
	    info->flags & ~XT_STATISTIC_MASK)
		return false;

	info->master = kzalloc(sizeof(*info->master), GFP_KERNEL);
	if (info->master == NULL) {
		printk(KERN_ERR KBUILD_MODNAME ": Out of memory\n");
		return false;
	}
	info->master->count = info->u.nth.count;

	return true;
}

static void statistic_mt_destroy(const struct xt_mtdtor_param *par)
{
	const struct xt_statistic_info *info = par->matchinfo;

	kfree(info->master);
}

static struct xt_match xt_statistic_mt_reg __read_mostly = {
	.name       = "statistic",
	.revision   = 0,
	.family     = NFPROTO_UNSPEC,
	.match      = statistic_mt,
	.checkentry = statistic_mt_check,
	.destroy    = statistic_mt_destroy,
	.matchsize  = sizeof(struct xt_statistic_info),
	.me         = THIS_MODULE,
};

static int __init statistic_mt_init(void)
{
	return xt_register_match(&xt_statistic_mt_reg);
}

static void __exit statistic_mt_exit(void)
{
	xt_unregister_match(&xt_statistic_mt_reg);
}

module_init(statistic_mt_init);
module_exit(statistic_mt_exit);
Commit	Line	Data
f3389805 PM	1	/*
	2	* Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License version 2 as
	6	* published by the Free Software Foundation.
	7	*
	8	* Based on ipt_random and ipt_nth by Fabrice MARIE <fabrice@netfilter.org>.
	9	*/
	10
	11	#include <linux/init.h>
	12	#include <linux/spinlock.h>
	13	#include <linux/skbuff.h>
	14	#include <linux/net.h>
	15
	16	#include <linux/netfilter/xt_statistic.h>
	17	#include <linux/netfilter/x_tables.h>
	18
acc738fe JE	19	struct xt_statistic_priv {
	20	uint32_t count;
	21	};
	22
f3389805 PM	23	MODULE_LICENSE("GPL");
f3389805 PM	24	MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
2ae15b64	25	MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)");
f3389805 PM	26	MODULE_ALIAS("ipt_statistic");
	27	MODULE_ALIAS("ip6t_statistic");
	28
	29	static DEFINE_SPINLOCK(nth_lock);
	30
1d93a9cb	31	static bool
f7108a20	32	statistic_mt(const struct sk_buff skb, const struct xt_match_param par)
f3389805	33	{
acc738fe	34	const struct xt_statistic_info *info = par->matchinfo;
1d93a9cb	35	bool ret = info->flags & XT_STATISTIC_INVERT;
f3389805 PM	36
	37	switch (info->mode) {
	38	case XT_STATISTIC_MODE_RANDOM:
	39	if ((net_random() & 0x7FFFFFFF) < info->u.random.probability)
1d93a9cb	40	ret = !ret;
f3389805 PM	41	break;
f3389805 PM	42	case XT_STATISTIC_MODE_NTH:
f3389805	43	spin_lock_bh(&nth_lock);
acc738fe JE	44	if (info->master->count++ == info->u.nth.every) {
acc738fe JE	45	info->master->count = 0;
1d93a9cb	46	ret = !ret;
f3389805 PM	47	}
	48	spin_unlock_bh(&nth_lock);
	49	break;
	50	}
	51
	52	return ret;
	53	}
	54
9b4fce7a	55	static bool statistic_mt_check(const struct xt_mtchk_param *par)
f3389805	56	{
9b4fce7a	57	struct xt_statistic_info *info = par->matchinfo;
f3389805 PM	58
	59	if (info->mode > XT_STATISTIC_MODE_MAX \|\|
	60	info->flags & ~XT_STATISTIC_MASK)
ccb79bdc	61	return false;
acc738fe JE	62
	63	info->master = kzalloc(sizeof(*info->master), GFP_KERNEL);
	64	if (info->master == NULL) {
	65	printk(KERN_ERR KBUILD_MODNAME ": Out of memory\n");
	66	return false;
	67	}
	68	info->master->count = info->u.nth.count;
	69
ccb79bdc	70	return true;
f3389805 PM	71	}
f3389805 PM	72
acc738fe JE	73	static void statistic_mt_destroy(const struct xt_mtdtor_param *par)
	74	{
	75	const struct xt_statistic_info *info = par->matchinfo;
	76
	77	kfree(info->master);
	78	}
	79
55b69e91 JE	80	static struct xt_match xt_statistic_mt_reg __read_mostly = {
	81	.name = "statistic",
	82	.revision = 0,
	83	.family = NFPROTO_UNSPEC,
	84	.match = statistic_mt,
	85	.checkentry = statistic_mt_check,
acc738fe	86	.destroy = statistic_mt_destroy,
55b69e91 JE	87	.matchsize = sizeof(struct xt_statistic_info),
55b69e91 JE	88	.me = THIS_MODULE,
f3389805 PM	89	};
f3389805 PM	90
d3c5ee6d	91	static int __init statistic_mt_init(void)
f3389805	92	{
55b69e91	93	return xt_register_match(&xt_statistic_mt_reg);
f3389805 PM	94	}
f3389805 PM	95
d3c5ee6d	96	static void __exit statistic_mt_exit(void)
f3389805	97	{
55b69e91	98	xt_unregister_match(&xt_statistic_mt_reg);
f3389805 PM	99	}
f3389805 PM	100
d3c5ee6d JE	101	module_init(statistic_mt_init);
d3c5ee6d JE	102	module_exit(statistic_mt_exit);