Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
1/* String matching match for iptables
2 *
3 * (C) 2005 Pablo Neira Ayuso <pablo@eurodev.net>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9
10#include <linux/init.h>
11#include <linux/module.h>
12#include <linux/kernel.h>
13#include <linux/skbuff.h>
14#include <linux/netfilter/x_tables.h>
15#include <linux/netfilter/xt_string.h>
16#include <linux/textsearch.h>
17
18MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");
19MODULE_DESCRIPTION("IP tables string match module");
20MODULE_LICENSE("GPL");
21MODULE_ALIAS("ipt_string");
22MODULE_ALIAS("ip6t_string");
23
24static int match(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 struct ts_state state;
33 struct xt_string_info *conf = (struct xt_string_info *) matchinfo;
34
35 memset(&state, 0, sizeof(struct ts_state));
36
37 return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
38 conf->to_offset, conf->config, &state)
39 != UINT_MAX) && !conf->invert;
40}
41
42#define STRING_TEXT_PRIV(m) ((struct xt_string_info *) m)
43
44static int checkentry(const char *tablename,
45 const void *ip,
46 void *matchinfo,
47 unsigned int matchsize,
48 unsigned int hook_mask)
49{
50 struct xt_string_info *conf = matchinfo;
51 struct ts_config *ts_conf;
52
53 if (matchsize != XT_ALIGN(sizeof(struct xt_string_info)))
54 return 0;
55
56 /* Damn, can't handle this case properly with iptables... */
57 if (conf->from_offset > conf->to_offset)
58 return 0;
59
60 ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
61 GFP_KERNEL, TS_AUTOLOAD);
62 if (IS_ERR(ts_conf))
63 return 0;
64
65 conf->config = ts_conf;
66
67 return 1;
68}
69
70static void destroy(void *matchinfo, unsigned int matchsize)
71{
72 textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
73}
74
75static struct xt_match string_match = {
76 .name = "string",
77 .match = match,
78 .checkentry = checkentry,
79 .destroy = destroy,
80 .me = THIS_MODULE
81};
82static struct xt_match string6_match = {
83 .name = "string",
84 .match = match,
85 .checkentry = checkentry,
86 .destroy = destroy,
87 .me = THIS_MODULE
88};
89
90static int __init init(void)
91{
92 int ret;
93
94 ret = xt_register_match(AF_INET, &string_match);
95 if (ret)
96 return ret;
97 ret = xt_register_match(AF_INET6, &string6_match);
98 if (ret)
99 xt_unregister_match(AF_INET, &string_match);
100
101 return ret;
102}
103
104static void __exit fini(void)
105{
106 xt_unregister_match(AF_INET, &string_match);
107 xt_unregister_match(AF_INET6, &string6_match);
108}
109
110module_init(init);
111module_exit(fini);