xt_state.c revision 2e4e6a17af35be359cc8f1c924f8f198fbd478cc 
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 void *matchinfo,
28      int offset,
29      unsigned int protoff,
30      int *hotdrop)
31{
32	const struct xt_state_info *sinfo = matchinfo;
33	enum ip_conntrack_info ctinfo;
34	unsigned int statebit;
35
36	if (nf_ct_is_untracked(skb))
37		statebit = XT_STATE_UNTRACKED;
38	else if (!nf_ct_get_ctinfo(skb, &ctinfo))
39		statebit = XT_STATE_INVALID;
40	else
41		statebit = XT_STATE_BIT(ctinfo);
42
43	return (sinfo->statemask & statebit);
44}
45
46static int check(const char *tablename,
47		 const void *ip,
48		 void *matchinfo,
49		 unsigned int matchsize,
50		 unsigned int hook_mask)
51{
52	if (matchsize != XT_ALIGN(sizeof(struct xt_state_info)))
53		return 0;
54
55	return 1;
56}
57
58static struct xt_match state_match = {
59	.name		= "state",
60	.match		= &match,
61	.checkentry	= &check,
62	.me		= THIS_MODULE,
63};
64
65static struct xt_match state6_match = {
66	.name		= "state",
67	.match		= &match,
68	.checkentry	= &check,
69	.me		= THIS_MODULE,
70};
71
72static int __init init(void)
73{
74	int ret;
75
76	need_conntrack();
77
78	ret = xt_register_match(AF_INET, &state_match);
79	if (ret < 0)
80		return ret;
81
82	ret = xt_register_match(AF_INET6, &state6_match);
83	if (ret < 0)
84		xt_unregister_match(AF_INET,&state_match);
85
86	return ret;
87}
88
89static void __exit fini(void)
90{
91	xt_unregister_match(AF_INET, &state_match);
92	xt_unregister_match(AF_INET6, &state6_match);
93}
94
95module_init(init);
96module_exit(fini);
97