xt_state.c revision c49867347404c46f137a261643ed4fce4376f324 
1/* Kernel module to match connection tracking information. */
2
3/* (C) 1999-2001 Paul `Rusty' Russell
4 * (C) 2002-2005 Netfilter Core Team <coreteam@netfilter.org>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <linux/module.h>
12#include <linux/skbuff.h>
13#include <net/netfilter/nf_conntrack_compat.h>
14#include <linux/netfilter/x_tables.h>
15#include <linux/netfilter/xt_state.h>
16
17MODULE_LICENSE("GPL");
18MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
19MODULE_DESCRIPTION("ip[6]_tables connection tracking state match module");
20MODULE_ALIAS("ipt_state");
21MODULE_ALIAS("ip6t_state");
22
23static int
24match(const struct sk_buff *skb,
25      const struct net_device *in,
26      const struct net_device *out,
27      const struct xt_match *match,
28      const void *matchinfo,
29      int offset,
30      unsigned int protoff,
31      int *hotdrop)
32{
33	const struct xt_state_info *sinfo = matchinfo;
34	enum ip_conntrack_info ctinfo;
35	unsigned int statebit;
36
37	if (nf_ct_is_untracked(skb))
38		statebit = XT_STATE_UNTRACKED;
39	else if (!nf_ct_get_ctinfo(skb, &ctinfo))
40		statebit = XT_STATE_INVALID;
41	else
42		statebit = XT_STATE_BIT(ctinfo);
43
44	return (sinfo->statemask & statebit);
45}
46
47static struct xt_match state_match = {
48	.name		= "state",
49	.match		= match,
50	.matchsize	= sizeof(struct xt_state_info),
51	.me		= THIS_MODULE,
52};
53
54static struct xt_match state6_match = {
55	.name		= "state",
56	.match		= match,
57	.matchsize	= sizeof(struct xt_state_info),
58	.me		= THIS_MODULE,
59};
60
61static int __init init(void)
62{
63	int ret;
64
65	need_conntrack();
66
67	ret = xt_register_match(AF_INET, &state_match);
68	if (ret < 0)
69		return ret;
70
71	ret = xt_register_match(AF_INET6, &state6_match);
72	if (ret < 0)
73		xt_unregister_match(AF_INET,&state_match);
74
75	return ret;
76}
77
78static void __exit fini(void)
79{
80	xt_unregister_match(AF_INET, &state_match);
81	xt_unregister_match(AF_INET6, &state6_match);
82}
83
84module_init(init);
85module_exit(fini);
86