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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 | ||
19 | MODULE_LICENSE("GPL"); | |
20 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); | |
2ae15b64 | 21 | MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)"); |
f3389805 PM |
22 | MODULE_ALIAS("ipt_statistic"); |
23 | MODULE_ALIAS("ip6t_statistic"); | |
24 | ||
25 | static DEFINE_SPINLOCK(nth_lock); | |
26 | ||
1d93a9cb | 27 | static bool |
f7108a20 | 28 | statistic_mt(const struct sk_buff *skb, const struct xt_match_param *par) |
f3389805 | 29 | { |
f7108a20 | 30 | struct xt_statistic_info *info = (void *)par->matchinfo; |
1d93a9cb | 31 | bool ret = info->flags & XT_STATISTIC_INVERT; |
f3389805 PM |
32 | |
33 | switch (info->mode) { | |
34 | case XT_STATISTIC_MODE_RANDOM: | |
35 | if ((net_random() & 0x7FFFFFFF) < info->u.random.probability) | |
1d93a9cb | 36 | ret = !ret; |
f3389805 PM |
37 | break; |
38 | case XT_STATISTIC_MODE_NTH: | |
39 | info = info->master; | |
40 | spin_lock_bh(&nth_lock); | |
41 | if (info->u.nth.count++ == info->u.nth.every) { | |
42 | info->u.nth.count = 0; | |
1d93a9cb | 43 | ret = !ret; |
f3389805 PM |
44 | } |
45 | spin_unlock_bh(&nth_lock); | |
46 | break; | |
47 | } | |
48 | ||
49 | return ret; | |
50 | } | |
51 | ||
9b4fce7a | 52 | static bool statistic_mt_check(const struct xt_mtchk_param *par) |
f3389805 | 53 | { |
9b4fce7a | 54 | struct xt_statistic_info *info = par->matchinfo; |
f3389805 PM |
55 | |
56 | if (info->mode > XT_STATISTIC_MODE_MAX || | |
57 | info->flags & ~XT_STATISTIC_MASK) | |
ccb79bdc | 58 | return false; |
f3389805 | 59 | info->master = info; |
ccb79bdc | 60 | return true; |
f3389805 PM |
61 | } |
62 | ||
55b69e91 JE |
63 | static struct xt_match xt_statistic_mt_reg __read_mostly = { |
64 | .name = "statistic", | |
65 | .revision = 0, | |
66 | .family = NFPROTO_UNSPEC, | |
67 | .match = statistic_mt, | |
68 | .checkentry = statistic_mt_check, | |
69 | .matchsize = sizeof(struct xt_statistic_info), | |
70 | .me = THIS_MODULE, | |
f3389805 PM |
71 | }; |
72 | ||
d3c5ee6d | 73 | static int __init statistic_mt_init(void) |
f3389805 | 74 | { |
55b69e91 | 75 | return xt_register_match(&xt_statistic_mt_reg); |
f3389805 PM |
76 | } |
77 | ||
d3c5ee6d | 78 | static void __exit statistic_mt_exit(void) |
f3389805 | 79 | { |
55b69e91 | 80 | xt_unregister_match(&xt_statistic_mt_reg); |
f3389805 PM |
81 | } |
82 | ||
d3c5ee6d JE |
83 | module_init(statistic_mt_init); |
84 | module_exit(statistic_mt_exit); |