Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
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 matchsize,
50 unsigned int hook_mask)
51{
52 struct xt_string_info *conf = matchinfo;
53 struct ts_config *ts_conf;
54
55 /* Damn, can't handle this case properly with iptables... */
56 if (conf->from_offset > conf->to_offset)
57 return 0;
58 if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
59 return 0;
60 if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
61 return 0;
62 ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
63 GFP_KERNEL, TS_AUTOLOAD);
64 if (IS_ERR(ts_conf))
65 return 0;
66
67 conf->config = ts_conf;
68
69 return 1;
70}
71
72static void destroy(const struct xt_match *match, void *matchinfo,
73 unsigned int matchsize)
74{
75 textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
76}
77
78static struct xt_match string_match = {
79 .name = "string",
80 .match = match,
81 .matchsize = sizeof(struct xt_string_info),
82 .checkentry = checkentry,
83 .destroy = destroy,
84 .family = AF_INET,
85 .me = THIS_MODULE
86};
87static struct xt_match string6_match = {
88 .name = "string",
89 .match = match,
90 .matchsize = sizeof(struct xt_string_info),
91 .checkentry = checkentry,
92 .destroy = destroy,
93 .family = AF_INET6,
94 .me = THIS_MODULE
95};
96
97static int __init xt_string_init(void)
98{
99 int ret;
100
101 ret = xt_register_match(&string_match);
102 if (ret)
103 return ret;
104 ret = xt_register_match(&string6_match);
105 if (ret)
106 xt_unregister_match(&string_match);
107
108 return ret;
109}
110
111static void __exit xt_string_fini(void)
112{
113 xt_unregister_match(&string_match);
114 xt_unregister_match(&string6_match);
115}
116
117module_init(xt_string_init);
118module_exit(xt_string_fini);