tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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#include <linux/slab.h>
16
17#include <linux/netfilter/xt_statistic.h>
18#include <linux/netfilter/x_tables.h>
19
20struct xt_statistic_priv {
21 uint32_t count;
22};
23
24MODULE_LICENSE("GPL");
25MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
26MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)");
27MODULE_ALIAS("ipt_statistic");
28MODULE_ALIAS("ip6t_statistic");
29
30static DEFINE_SPINLOCK(nth_lock);
31
32static bool
33statistic_mt(const struct sk_buff *skb, struct xt_action_param *par)
34{
35 const struct xt_statistic_info *info = par->matchinfo;
36 bool ret = info->flags & XT_STATISTIC_INVERT;
37
38 switch (info->mode) {
39 case XT_STATISTIC_MODE_RANDOM:
40 if ((net_random() & 0x7FFFFFFF) < info->u.random.probability)
41 ret = !ret;
42 break;
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;
47 ret = !ret;
48 }
49 spin_unlock_bh(&nth_lock);
50 break;
51 }
52
53 return ret;
54}
55
56static int statistic_mt_check(const struct xt_mtchk_param *par)
57{
58 struct xt_statistic_info *info = par->matchinfo;
59
60 if (info->mode > XT_STATISTIC_MODE_MAX ||
61 info->flags & ~XT_STATISTIC_MASK)
62 return -EINVAL;
63
64 info->master = kzalloc(sizeof(*info->master), GFP_KERNEL);
65 if (info->master == NULL)
66 return -ENOMEM;
67 info->master->count = info->u.nth.count;
68
69 return 0;
70}
71
72static void statistic_mt_destroy(const struct xt_mtdtor_param *par)
73{
74 const struct xt_statistic_info *info = par->matchinfo;
75
76 kfree(info->master);
77}
78
79static struct xt_match xt_statistic_mt_reg __read_mostly = {
80 .name = "statistic",
81 .revision = 0,
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),
87 .me = THIS_MODULE,
88};
89
90static int __init statistic_mt_init(void)
91{
92 return xt_register_match(&xt_statistic_mt_reg);
93}
94
95static void __exit statistic_mt_exit(void)
96{
97 xt_unregister_match(&xt_statistic_mt_reg);
98}
99
100module_init(statistic_mt_init);
101module_exit(statistic_mt_exit);