Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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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 struct xt_match *match,
28 const void *matchinfo,
29 int offset,
30 unsigned int protoff,
31 int *hotdrop)
32{
33 const struct xt_string_info *conf = matchinfo;
34 struct ts_state state;
35
36 memset(&state, 0, sizeof(struct ts_state));
37
38 return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
39 conf->to_offset, conf->config, &state)
40 != UINT_MAX) ^ conf->invert;
41}
42
43#define STRING_TEXT_PRIV(m) ((struct xt_string_info *) m)
44
45static int checkentry(const char *tablename,
46 const void *ip,
47 const struct xt_match *match,
48 void *matchinfo,
49 unsigned int hook_mask)
50{
51 struct xt_string_info *conf = matchinfo;
52 struct ts_config *ts_conf;
53
54 /* Damn, can't handle this case properly with iptables... */
55 if (conf->from_offset > conf->to_offset)
56 return 0;
57 if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
58 return 0;
59 if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
60 return 0;
61 ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
62 GFP_KERNEL, TS_AUTOLOAD);
63 if (IS_ERR(ts_conf))
64 return 0;
65
66 conf->config = ts_conf;
67
68 return 1;
69}
70
71static void destroy(const struct xt_match *match, void *matchinfo)
72{
73 textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
74}
75
76static struct xt_match xt_string_match[] = {
77 {
78 .name = "string",
79 .family = AF_INET,
80 .checkentry = checkentry,
81 .match = match,
82 .destroy = destroy,
83 .matchsize = sizeof(struct xt_string_info),
84 .me = THIS_MODULE
85 },
86 {
87 .name = "string",
88 .family = AF_INET6,
89 .checkentry = checkentry,
90 .match = match,
91 .destroy = destroy,
92 .matchsize = sizeof(struct xt_string_info),
93 .me = THIS_MODULE
94 },
95};
96
97static int __init xt_string_init(void)
98{
99 return xt_register_matches(xt_string_match, ARRAY_SIZE(xt_string_match));
100}
101
102static void __exit xt_string_fini(void)
103{
104 xt_unregister_matches(xt_string_match, ARRAY_SIZE(xt_string_match));
105}
106
107module_init(xt_string_init);
108module_exit(xt_string_fini);