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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>"); | |
21 | MODULE_DESCRIPTION("xtables statistical match module"); | |
22 | MODULE_ALIAS("ipt_statistic"); | |
23 | MODULE_ALIAS("ip6t_statistic"); | |
24 | ||
25 | static DEFINE_SPINLOCK(nth_lock); | |
26 | ||
27 | static int | |
28 | match(const struct sk_buff *skb, | |
29 | const struct net_device *in, const struct net_device *out, | |
30 | const struct xt_match *match, const void *matchinfo, | |
cff533ac | 31 | int offset, unsigned int protoff, bool *hotdrop) |
f3389805 PM |
32 | { |
33 | struct xt_statistic_info *info = (struct xt_statistic_info *)matchinfo; | |
34 | int ret = info->flags & XT_STATISTIC_INVERT ? 1 : 0; | |
35 | ||
36 | switch (info->mode) { | |
37 | case XT_STATISTIC_MODE_RANDOM: | |
38 | if ((net_random() & 0x7FFFFFFF) < info->u.random.probability) | |
39 | ret ^= 1; | |
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 ^= 1; | |
47 | } | |
48 | spin_unlock_bh(&nth_lock); | |
49 | break; | |
50 | } | |
51 | ||
52 | return ret; | |
53 | } | |
54 | ||
55 | static int | |
56 | checkentry(const char *tablename, const void *entry, | |
57 | const struct xt_match *match, void *matchinfo, | |
efa74165 | 58 | unsigned int hook_mask) |
f3389805 PM |
59 | { |
60 | struct xt_statistic_info *info = (struct xt_statistic_info *)matchinfo; | |
61 | ||
62 | if (info->mode > XT_STATISTIC_MODE_MAX || | |
63 | info->flags & ~XT_STATISTIC_MASK) | |
64 | return 0; | |
65 | info->master = info; | |
66 | return 1; | |
67 | } | |
68 | ||
4470bbc7 PM |
69 | static struct xt_match xt_statistic_match[] = { |
70 | { | |
71 | .name = "statistic", | |
72 | .family = AF_INET, | |
73 | .checkentry = checkentry, | |
74 | .match = match, | |
75 | .matchsize = sizeof(struct xt_statistic_info), | |
76 | .me = THIS_MODULE, | |
77 | }, | |
78 | { | |
79 | .name = "statistic", | |
80 | .family = AF_INET6, | |
81 | .checkentry = checkentry, | |
82 | .match = match, | |
83 | .matchsize = sizeof(struct xt_statistic_info), | |
84 | .me = THIS_MODULE, | |
85 | }, | |
f3389805 PM |
86 | }; |
87 | ||
88 | static int __init xt_statistic_init(void) | |
89 | { | |
4470bbc7 PM |
90 | return xt_register_matches(xt_statistic_match, |
91 | ARRAY_SIZE(xt_statistic_match)); | |
f3389805 PM |
92 | } |
93 | ||
94 | static void __exit xt_statistic_fini(void) | |
95 | { | |
4470bbc7 PM |
96 | xt_unregister_matches(xt_statistic_match, |
97 | ARRAY_SIZE(xt_statistic_match)); | |
f3389805 PM |
98 | } |
99 | ||
100 | module_init(xt_statistic_init); | |
101 | module_exit(xt_statistic_fini); |