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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 | ||
acc738fe JE |
19 | struct xt_statistic_priv { |
20 | uint32_t count; | |
21 | }; | |
22 | ||
f3389805 PM |
23 | MODULE_LICENSE("GPL"); |
24 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); | |
2ae15b64 | 25 | MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)"); |
f3389805 PM |
26 | MODULE_ALIAS("ipt_statistic"); |
27 | MODULE_ALIAS("ip6t_statistic"); | |
28 | ||
29 | static DEFINE_SPINLOCK(nth_lock); | |
30 | ||
1d93a9cb | 31 | static bool |
f7108a20 | 32 | statistic_mt(const struct sk_buff *skb, const struct xt_match_param *par) |
f3389805 | 33 | { |
acc738fe | 34 | const struct xt_statistic_info *info = par->matchinfo; |
1d93a9cb | 35 | bool ret = info->flags & XT_STATISTIC_INVERT; |
f3389805 PM |
36 | |
37 | switch (info->mode) { | |
38 | case XT_STATISTIC_MODE_RANDOM: | |
39 | if ((net_random() & 0x7FFFFFFF) < info->u.random.probability) | |
1d93a9cb | 40 | ret = !ret; |
f3389805 PM |
41 | break; |
42 | case XT_STATISTIC_MODE_NTH: | |
f3389805 | 43 | spin_lock_bh(&nth_lock); |
acc738fe JE |
44 | if (info->master->count++ == info->u.nth.every) { |
45 | info->master->count = 0; | |
1d93a9cb | 46 | ret = !ret; |
f3389805 PM |
47 | } |
48 | spin_unlock_bh(&nth_lock); | |
49 | break; | |
50 | } | |
51 | ||
52 | return ret; | |
53 | } | |
54 | ||
9b4fce7a | 55 | static bool statistic_mt_check(const struct xt_mtchk_param *par) |
f3389805 | 56 | { |
9b4fce7a | 57 | struct xt_statistic_info *info = par->matchinfo; |
f3389805 PM |
58 | |
59 | if (info->mode > XT_STATISTIC_MODE_MAX || | |
60 | info->flags & ~XT_STATISTIC_MASK) | |
ccb79bdc | 61 | return false; |
acc738fe JE |
62 | |
63 | info->master = kzalloc(sizeof(*info->master), GFP_KERNEL); | |
64 | if (info->master == NULL) { | |
65 | printk(KERN_ERR KBUILD_MODNAME ": Out of memory\n"); | |
66 | return false; | |
67 | } | |
68 | info->master->count = info->u.nth.count; | |
69 | ||
ccb79bdc | 70 | return true; |
f3389805 PM |
71 | } |
72 | ||
acc738fe JE |
73 | static void statistic_mt_destroy(const struct xt_mtdtor_param *par) |
74 | { | |
75 | const struct xt_statistic_info *info = par->matchinfo; | |
76 | ||
77 | kfree(info->master); | |
78 | } | |
79 | ||
55b69e91 JE |
80 | static struct xt_match xt_statistic_mt_reg __read_mostly = { |
81 | .name = "statistic", | |
82 | .revision = 0, | |
83 | .family = NFPROTO_UNSPEC, | |
84 | .match = statistic_mt, | |
85 | .checkentry = statistic_mt_check, | |
acc738fe | 86 | .destroy = statistic_mt_destroy, |
55b69e91 JE |
87 | .matchsize = sizeof(struct xt_statistic_info), |
88 | .me = THIS_MODULE, | |
f3389805 PM |
89 | }; |
90 | ||
d3c5ee6d | 91 | static int __init statistic_mt_init(void) |
f3389805 | 92 | { |
55b69e91 | 93 | return xt_register_match(&xt_statistic_mt_reg); |
f3389805 PM |
94 | } |
95 | ||
d3c5ee6d | 96 | static void __exit statistic_mt_exit(void) |
f3389805 | 97 | { |
55b69e91 | 98 | xt_unregister_match(&xt_statistic_mt_reg); |
f3389805 PM |
99 | } |
100 | ||
d3c5ee6d JE |
101 | module_init(statistic_mt_init); |
102 | module_exit(statistic_mt_exit); |