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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> | |
5a0e3ad6 | 15 | #include <linux/slab.h> |
f3389805 PM |
16 | |
17 | #include <linux/netfilter/xt_statistic.h> | |
18 | #include <linux/netfilter/x_tables.h> | |
19 | ||
acc738fe | 20 | struct xt_statistic_priv { |
fabf3a85 ED |
21 | atomic_t count; |
22 | } ____cacheline_aligned_in_smp; | |
acc738fe | 23 | |
f3389805 PM |
24 | MODULE_LICENSE("GPL"); |
25 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); | |
2ae15b64 | 26 | MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)"); |
f3389805 PM |
27 | MODULE_ALIAS("ipt_statistic"); |
28 | MODULE_ALIAS("ip6t_statistic"); | |
29 | ||
1d93a9cb | 30 | static bool |
62fc8051 | 31 | statistic_mt(const struct sk_buff *skb, struct xt_action_param *par) |
f3389805 | 32 | { |
acc738fe | 33 | const struct xt_statistic_info *info = par->matchinfo; |
1d93a9cb | 34 | bool ret = info->flags & XT_STATISTIC_INVERT; |
fabf3a85 | 35 | int nval, oval; |
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: | |
fabf3a85 ED |
43 | do { |
44 | oval = atomic_read(&info->master->count); | |
45 | nval = (oval == info->u.nth.every) ? 0 : oval + 1; | |
46 | } while (atomic_cmpxchg(&info->master->count, oval, nval) != oval); | |
47 | if (nval == 0) | |
1d93a9cb | 48 | ret = !ret; |
f3389805 PM |
49 | break; |
50 | } | |
51 | ||
52 | return ret; | |
53 | } | |
54 | ||
b0f38452 | 55 | static int 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) | |
bd414ee6 | 61 | return -EINVAL; |
acc738fe JE |
62 | |
63 | info->master = kzalloc(sizeof(*info->master), GFP_KERNEL); | |
85bc3f38 | 64 | if (info->master == NULL) |
4a5a5c73 | 65 | return -ENOMEM; |
fabf3a85 | 66 | atomic_set(&info->master->count, info->u.nth.count); |
acc738fe | 67 | |
bd414ee6 | 68 | return 0; |
f3389805 PM |
69 | } |
70 | ||
acc738fe JE |
71 | static void statistic_mt_destroy(const struct xt_mtdtor_param *par) |
72 | { | |
73 | const struct xt_statistic_info *info = par->matchinfo; | |
74 | ||
75 | kfree(info->master); | |
76 | } | |
77 | ||
55b69e91 JE |
78 | static struct xt_match xt_statistic_mt_reg __read_mostly = { |
79 | .name = "statistic", | |
80 | .revision = 0, | |
81 | .family = NFPROTO_UNSPEC, | |
82 | .match = statistic_mt, | |
83 | .checkentry = statistic_mt_check, | |
acc738fe | 84 | .destroy = statistic_mt_destroy, |
55b69e91 JE |
85 | .matchsize = sizeof(struct xt_statistic_info), |
86 | .me = THIS_MODULE, | |
f3389805 PM |
87 | }; |
88 | ||
d3c5ee6d | 89 | static int __init statistic_mt_init(void) |
f3389805 | 90 | { |
55b69e91 | 91 | return xt_register_match(&xt_statistic_mt_reg); |
f3389805 PM |
92 | } |
93 | ||
d3c5ee6d | 94 | static void __exit statistic_mt_exit(void) |
f3389805 | 95 | { |
55b69e91 | 96 | xt_unregister_match(&xt_statistic_mt_reg); |
f3389805 PM |
97 | } |
98 | ||
d3c5ee6d JE |
99 | module_init(statistic_mt_init); |
100 | module_exit(statistic_mt_exit); |