summaryrefslogtreecommitdiff
path: root/net/netfilter/xt_string.c
blob: 999a005dbd0cb5c73c0285f3241b03794f7a9418 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
/* String matching match for iptables
 *
 * (C) 2005 Pablo Neira Ayuso <pablo@eurodev.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_string.h>
#include <linux/textsearch.h>

MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");
MODULE_DESCRIPTION("IP tables string match module");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_string");
MODULE_ALIAS("ip6t_string");

static int match(const struct sk_buff *skb,
		 const struct net_device *in,
		 const struct net_device *out,
		 const struct xt_match *match,
		 const void *matchinfo,
		 int offset,
		 unsigned int protoff,
		 int *hotdrop)
{
	const struct xt_string_info *conf = matchinfo;
	struct ts_state state;

	memset(&state, 0, sizeof(struct ts_state));

	return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
			     conf->to_offset, conf->config, &state)
			     != UINT_MAX) ^ conf->invert;
}

#define STRING_TEXT_PRIV(m) ((struct xt_string_info *) m)

static int checkentry(const char *tablename,
		      const void *ip,
		      const struct xt_match *match,
		      void *matchinfo,
		      unsigned int hook_mask)
{
	struct xt_string_info *conf = matchinfo;
	struct ts_config *ts_conf;

	/* Damn, can't handle this case properly with iptables... */
	if (conf->from_offset > conf->to_offset)
		return 0;
	if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
		return 0;
	if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
		return 0;
	ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
				     GFP_KERNEL, TS_AUTOLOAD);
	if (IS_ERR(ts_conf))
		return 0;

	conf->config = ts_conf;

	return 1;
}

static void destroy(const struct xt_match *match, void *matchinfo)
{
	textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
}

static struct xt_match xt_string_match[] = {
	{
		.name 		= "string",
		.family		= AF_INET,
		.checkentry	= checkentry,
		.match 		= match,
		.destroy 	= destroy,
		.matchsize	= sizeof(struct xt_string_info),
		.me 		= THIS_MODULE
	},
	{
		.name 		= "string",
		.family		= AF_INET6,
		.checkentry	= checkentry,
		.match 		= match,
		.destroy 	= destroy,
		.matchsize	= sizeof(struct xt_string_info),
		.me 		= THIS_MODULE
	},
};

static int __init xt_string_init(void)
{
	return xt_register_matches(xt_string_match, ARRAY_SIZE(xt_string_match));
}

static void __exit xt_string_fini(void)
{
	xt_unregister_matches(xt_string_match, ARRAY_SIZE(xt_string_match));
}

module_init(xt_string_init);
module_exit(xt_string_fini);