2 * Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
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.
8 * Based on ipt_random and ipt_nth by Fabrice MARIE <fabrice@netfilter.org>.
11 #include <linux/init.h>
12 #include <linux/spinlock.h>
13 #include <linux/skbuff.h>
14 #include <linux/net.h>
15 #include <linux/slab.h>
17 #include <linux/netfilter/xt_statistic.h>
18 #include <linux/netfilter/x_tables.h>
20 struct xt_statistic_priv {
24 MODULE_LICENSE("GPL");
25 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
26 MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)");
27 MODULE_ALIAS("ipt_statistic");
28 MODULE_ALIAS("ip6t_statistic");
30 static DEFINE_SPINLOCK(nth_lock);
33 statistic_mt(const struct sk_buff *skb, const struct xt_match_param *par)
35 const struct xt_statistic_info *info = par->matchinfo;
36 bool ret = info->flags & XT_STATISTIC_INVERT;
39 case XT_STATISTIC_MODE_RANDOM:
40 if ((net_random() & 0x7FFFFFFF) < info->u.random.probability)
43 case XT_STATISTIC_MODE_NTH:
44 spin_lock_bh(&nth_lock);
45 if (info->master->count++ == info->u.nth.every) {
46 info->master->count = 0;
49 spin_unlock_bh(&nth_lock);
56 static int statistic_mt_check(const struct xt_mtchk_param *par)
58 struct xt_statistic_info *info = par->matchinfo;
60 if (info->mode > XT_STATISTIC_MODE_MAX ||
61 info->flags & ~XT_STATISTIC_MASK)
64 info->master = kzalloc(sizeof(*info->master), GFP_KERNEL);
65 if (info->master == NULL)
67 info->master->count = info->u.nth.count;
72 static void statistic_mt_destroy(const struct xt_mtdtor_param *par)
74 const struct xt_statistic_info *info = par->matchinfo;
79 static struct xt_match xt_statistic_mt_reg __read_mostly = {
82 .family = NFPROTO_UNSPEC,
83 .match = statistic_mt,
84 .checkentry = statistic_mt_check,
85 .destroy = statistic_mt_destroy,
86 .matchsize = sizeof(struct xt_statistic_info),
90 static int __init statistic_mt_init(void)
92 return xt_register_match(&xt_statistic_mt_reg);
95 static void __exit statistic_mt_exit(void)
97 xt_unregister_match(&xt_statistic_mt_reg);
100 module_init(statistic_mt_init);
101 module_exit(statistic_mt_exit);