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
16#include <linux/netfilter/xt_statistic.h>
17#include <linux/netfilter/x_tables.h>
18
19MODULE_LICENSE("GPL");
20MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
21MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)");
22MODULE_ALIAS("ipt_statistic");
23MODULE_ALIAS("ip6t_statistic");
24
25static DEFINE_SPINLOCK(nth_lock);
26
27static bool
28statistic_mt(const struct sk_buff *skb, const struct net_device *in,
29 const struct net_device *out, const struct xt_match *match,
30 const void *matchinfo, int offset, unsigned int protoff,
31 bool *hotdrop)
32{
33 struct xt_statistic_info *info = (struct xt_statistic_info *)matchinfo;
34 bool ret = info->flags & XT_STATISTIC_INVERT;
35
36 switch (info->mode) {
37 case XT_STATISTIC_MODE_RANDOM:
38 if ((net_random() & 0x7FFFFFFF) < info->u.random.probability)
39 ret = !ret;
40 break;
41 case XT_STATISTIC_MODE_NTH:
42 info = info->master;
43 spin_lock_bh(&nth_lock);
44 if (info->u.nth.count++ == info->u.nth.every) {
45 info->u.nth.count = 0;
46 ret = !ret;
47 }
48 spin_unlock_bh(&nth_lock);
49 break;
50 }
51
52 return ret;
53}
54
55static bool
56statistic_mt_check(const char *tablename, const void *entry,
57 const struct xt_match *match, void *matchinfo,
58 unsigned int hook_mask)
59{
60 struct xt_statistic_info *info = matchinfo;
61
62 if (info->mode > XT_STATISTIC_MODE_MAX ||
63 info->flags & ~XT_STATISTIC_MASK)
64 return false;
65 info->master = info;
66 return true;
67}
68
69static struct xt_match statistic_mt_reg[] __read_mostly = {
70 {
71 .name = "statistic",
72 .family = AF_INET,
73 .checkentry = statistic_mt_check,
74 .match = statistic_mt,
75 .matchsize = sizeof(struct xt_statistic_info),
76 .me = THIS_MODULE,
77 },
78 {
79 .name = "statistic",
80 .family = AF_INET6,
81 .checkentry = statistic_mt_check,
82 .match = statistic_mt,
83 .matchsize = sizeof(struct xt_statistic_info),
84 .me = THIS_MODULE,
85 },
86};
87
88static int __init statistic_mt_init(void)
89{
90 return xt_register_matches(statistic_mt_reg,
91 ARRAY_SIZE(statistic_mt_reg));
92}
93
94static void __exit statistic_mt_exit(void)
95{
96 xt_unregister_matches(statistic_mt_reg,
97 ARRAY_SIZE(statistic_mt_reg));
98}
99
100module_init(statistic_mt_init);
101module_exit(statistic_mt_exit);