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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#include <linux/slab.h>
16
17#include <linux/netfilter/xt_statistic.h>
18#include <linux/netfilter/x_tables.h>
19#include <linux/module.h>
20
21struct xt_statistic_priv {
22 atomic_t count;
23} ____cacheline_aligned_in_smp;
24
25MODULE_LICENSE("GPL");
26MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
27MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)");
28MODULE_ALIAS("ipt_statistic");
29MODULE_ALIAS("ip6t_statistic");
30
31static bool
32statistic_mt(const struct sk_buff *skb, struct xt_action_param *par)
33{
34 const struct xt_statistic_info *info = par->matchinfo;
35 bool ret = info->flags & XT_STATISTIC_INVERT;
36 int nval, oval;
37
38 switch (info->mode) {
39 case XT_STATISTIC_MODE_RANDOM:
40 if ((prandom_u32() & 0x7FFFFFFF) < info->u.random.probability)
41 ret = !ret;
42 break;
43 case XT_STATISTIC_MODE_NTH:
44 do {
45 oval = atomic_read(&info->master->count);
46 nval = (oval == info->u.nth.every) ? 0 : oval + 1;
47 } while (atomic_cmpxchg(&info->master->count, oval, nval) != oval);
48 if (nval == 0)
49 ret = !ret;
50 break;
51 }
52
53 return ret;
54}
55
56static int statistic_mt_check(const struct xt_mtchk_param *par)
57{
58 struct xt_statistic_info *info = par->matchinfo;
59
60 if (info->mode > XT_STATISTIC_MODE_MAX ||
61 info->flags & ~XT_STATISTIC_MASK)
62 return -EINVAL;
63
64 info->master = kzalloc(sizeof(*info->master), GFP_KERNEL);
65 if (info->master == NULL)
66 return -ENOMEM;
67 atomic_set(&info->master->count, info->u.nth.count);
68
69 return 0;
70}
71
72static void statistic_mt_destroy(const struct xt_mtdtor_param *par)
73{
74 const struct xt_statistic_info *info = par->matchinfo;
75
76 kfree(info->master);
77}
78
79static struct xt_match xt_statistic_mt_reg __read_mostly = {
80 .name = "statistic",
81 .revision = 0,
82 .family = NFPROTO_UNSPEC,
83 .match = statistic_mt,
84 .checkentry = statistic_mt_check,
85 .destroy = statistic_mt_destroy,
86 .matchsize = sizeof(struct xt_statistic_info),
87 .me = THIS_MODULE,
88};
89
90static int __init statistic_mt_init(void)
91{
92 return xt_register_match(&xt_statistic_mt_reg);
93}
94
95static void __exit statistic_mt_exit(void)
96{
97 xt_unregister_match(&xt_statistic_mt_reg);
98}
99
100module_init(statistic_mt_init);
101module_exit(statistic_mt_exit);
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#include <linux/slab.h>
16
17#include <linux/netfilter/xt_statistic.h>
18#include <linux/netfilter/x_tables.h>
19
20struct xt_statistic_priv {
21 atomic_t count;
22} ____cacheline_aligned_in_smp;
23
24MODULE_LICENSE("GPL");
25MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
26MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)");
27MODULE_ALIAS("ipt_statistic");
28MODULE_ALIAS("ip6t_statistic");
29
30static bool
31statistic_mt(const struct sk_buff *skb, struct xt_action_param *par)
32{
33 const struct xt_statistic_info *info = par->matchinfo;
34 bool ret = info->flags & XT_STATISTIC_INVERT;
35 int nval, oval;
36
37 switch (info->mode) {
38 case XT_STATISTIC_MODE_RANDOM:
39 if ((net_random() & 0x7FFFFFFF) < info->u.random.probability)
40 ret = !ret;
41 break;
42 case XT_STATISTIC_MODE_NTH:
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)
48 ret = !ret;
49 break;
50 }
51
52 return ret;
53}
54
55static int statistic_mt_check(const struct xt_mtchk_param *par)
56{
57 struct xt_statistic_info *info = par->matchinfo;
58
59 if (info->mode > XT_STATISTIC_MODE_MAX ||
60 info->flags & ~XT_STATISTIC_MASK)
61 return -EINVAL;
62
63 info->master = kzalloc(sizeof(*info->master), GFP_KERNEL);
64 if (info->master == NULL)
65 return -ENOMEM;
66 atomic_set(&info->master->count, info->u.nth.count);
67
68 return 0;
69}
70
71static 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
78static 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,
84 .destroy = statistic_mt_destroy,
85 .matchsize = sizeof(struct xt_statistic_info),
86 .me = THIS_MODULE,
87};
88
89static int __init statistic_mt_init(void)
90{
91 return xt_register_match(&xt_statistic_mt_reg);
92}
93
94static void __exit statistic_mt_exit(void)
95{
96 xt_unregister_match(&xt_statistic_mt_reg);
97}
98
99module_init(statistic_mt_init);
100module_exit(statistic_mt_exit);