// SPDX-License-Identifier: GPL-2.0-only
|
/*
|
* Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
|
*
|
* 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/slab.h>
|
|
#include <linux/netfilter/xt_statistic.h>
|
#include <linux/netfilter/x_tables.h>
|
#include <linux/module.h>
|
|
struct xt_statistic_priv {
|
atomic_t count;
|
} ____cacheline_aligned_in_smp;
|
|
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 bool
|
statistic_mt(const struct sk_buff *skb, struct xt_action_param *par)
|
{
|
const struct xt_statistic_info *info = par->matchinfo;
|
bool ret = info->flags & XT_STATISTIC_INVERT;
|
int nval, oval;
|
|
switch (info->mode) {
|
case XT_STATISTIC_MODE_RANDOM:
|
if ((prandom_u32() & 0x7FFFFFFF) < info->u.random.probability)
|
ret = !ret;
|
break;
|
case XT_STATISTIC_MODE_NTH:
|
do {
|
oval = atomic_read(&info->master->count);
|
nval = (oval == info->u.nth.every) ? 0 : oval + 1;
|
} while (atomic_cmpxchg(&info->master->count, oval, nval) != oval);
|
if (nval == 0)
|
ret = !ret;
|
break;
|
}
|
|
return ret;
|
}
|
|
static int 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 -EINVAL;
|
|
info->master = kzalloc(sizeof(*info->master), GFP_KERNEL);
|
if (info->master == NULL)
|
return -ENOMEM;
|
atomic_set(&info->master->count, info->u.nth.count);
|
|
return 0;
|
}
|
|
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),
|
.usersize = offsetof(struct xt_statistic_info, master),
|
.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);
|
