1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
 4 *
 
 
 
 
 5 * Based on ipt_random and ipt_nth by Fabrice MARIE <fabrice@netfilter.org>.
 6 */
 7
 8#include <linux/init.h>
 9#include <linux/spinlock.h>
10#include <linux/skbuff.h>
11#include <linux/net.h>
12#include <linux/slab.h>
13
14#include <linux/netfilter/xt_statistic.h>
15#include <linux/netfilter/x_tables.h>
16#include <linux/module.h>
17
18struct xt_statistic_priv {
19	atomic_t count;
20} ____cacheline_aligned_in_smp;
21
22MODULE_LICENSE("GPL");
23MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
24MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)");
25MODULE_ALIAS("ipt_statistic");
26MODULE_ALIAS("ip6t_statistic");
27
28static bool
29statistic_mt(const struct sk_buff *skb, struct xt_action_param *par)
30{
31	const struct xt_statistic_info *info = par->matchinfo;
32	bool ret = info->flags & XT_STATISTIC_INVERT;
33	int nval, oval;
34
35	switch (info->mode) {
36	case XT_STATISTIC_MODE_RANDOM:
37		if ((prandom_u32() & 0x7FFFFFFF) < info->u.random.probability)
38			ret = !ret;
39		break;
40	case XT_STATISTIC_MODE_NTH:
41		do {
42			oval = atomic_read(&info->master->count);
43			nval = (oval == info->u.nth.every) ? 0 : oval + 1;
44		} while (atomic_cmpxchg(&info->master->count, oval, nval) != oval);
45		if (nval == 0)
46			ret = !ret;
47		break;
48	}
49
50	return ret;
51}
52
53static int statistic_mt_check(const struct xt_mtchk_param *par)
54{
55	struct xt_statistic_info *info = par->matchinfo;
56
57	if (info->mode > XT_STATISTIC_MODE_MAX ||
58	    info->flags & ~XT_STATISTIC_MASK)
59		return -EINVAL;
60
61	info->master = kzalloc(sizeof(*info->master), GFP_KERNEL);
62	if (info->master == NULL)
63		return -ENOMEM;
64	atomic_set(&info->master->count, info->u.nth.count);
65
66	return 0;
67}
68
69static void statistic_mt_destroy(const struct xt_mtdtor_param *par)
70{
71	const struct xt_statistic_info *info = par->matchinfo;
72
73	kfree(info->master);
74}
75
76static struct xt_match xt_statistic_mt_reg __read_mostly = {
77	.name       = "statistic",
78	.revision   = 0,
79	.family     = NFPROTO_UNSPEC,
80	.match      = statistic_mt,
81	.checkentry = statistic_mt_check,
82	.destroy    = statistic_mt_destroy,
83	.matchsize  = sizeof(struct xt_statistic_info),
84	.usersize   = offsetof(struct xt_statistic_info, master),
85	.me         = THIS_MODULE,
86};
87
88static int __init statistic_mt_init(void)
89{
90	return xt_register_match(&xt_statistic_mt_reg);
91}
92
93static void __exit statistic_mt_exit(void)
94{
95	xt_unregister_match(&xt_statistic_mt_reg);
96}
97
98module_init(statistic_mt_init);
99module_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);