xt_state.c revision bd414ee605ff3ac5fcd79f57269a897879ee4cde 
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.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 bool
24state_mt(const struct sk_buff *skb, const struct xt_match_param *par)
25{
26	const struct xt_state_info *sinfo = par->matchinfo;
27	enum ip_conntrack_info ctinfo;
28	unsigned int statebit;
29
30	if (nf_ct_is_untracked(skb))
31		statebit = XT_STATE_UNTRACKED;
32	else if (!nf_ct_get(skb, &ctinfo))
33		statebit = XT_STATE_INVALID;
34	else
35		statebit = XT_STATE_BIT(ctinfo);
36
37	return (sinfo->statemask & statebit);
38}
39
40static int state_mt_check(const struct xt_mtchk_param *par)
41{
42	if (nf_ct_l3proto_try_module_get(par->family) < 0) {
43		pr_info("cannot load conntrack support for proto=%u\n",
44			par->family);
45		return -EINVAL;
46	}
47	return 0;
48}
49
50static void state_mt_destroy(const struct xt_mtdtor_param *par)
51{
52	nf_ct_l3proto_module_put(par->family);
53}
54
55static struct xt_match state_mt_reg[] __read_mostly = {
56	{
57		.name		= "state",
58		.family		= NFPROTO_IPV4,
59		.checkentry	= state_mt_check,
60		.match		= state_mt,
61		.destroy	= state_mt_destroy,
62		.matchsize	= sizeof(struct xt_state_info),
63		.me		= THIS_MODULE,
64	},
65	{
66		.name		= "state",
67		.family		= NFPROTO_IPV6,
68		.checkentry	= state_mt_check,
69		.match		= state_mt,
70		.destroy	= state_mt_destroy,
71		.matchsize	= sizeof(struct xt_state_info),
72		.me		= THIS_MODULE,
73	},
74};
75
76static int __init state_mt_init(void)
77{
78	return xt_register_matches(state_mt_reg, ARRAY_SIZE(state_mt_reg));
79}
80
81static void __exit state_mt_exit(void)
82{
83	xt_unregister_matches(state_mt_reg, ARRAY_SIZE(state_mt_reg));
84}
85
86module_init(state_mt_init);
87module_exit(state_mt_exit);
88