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("Xtables: string-based matching");
20MODULE_LICENSE("GPL");
21MODULE_ALIAS("ipt_string");
22MODULE_ALIAS("ip6t_string");
23
24static bool
25string_mt(const struct sk_buff *skb, const struct net_device *in,
26 const struct net_device *out, const struct xt_match *match,
27 const void *matchinfo, int offset, unsigned int protoff,
28 bool *hotdrop)
29{
30 const struct xt_string_info *conf = matchinfo;
31 struct ts_state state;
32 int invert;
33
34 memset(&state, 0, sizeof(struct ts_state));
35
36 invert = (match->revision == 0 ? conf->u.v0.invert :
37 conf->u.v1.flags & XT_STRING_FLAG_INVERT);
38
39 return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
40 conf->to_offset, conf->config, &state)
41 != UINT_MAX) ^ invert;
42}
43
44#define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))
45
46static bool
47string_mt_check(const char *tablename, const void *ip,
48 const struct xt_match *match, void *matchinfo,
49 unsigned int hook_mask)
50{
51 struct xt_string_info *conf = matchinfo;
52 struct ts_config *ts_conf;
53 int flags = TS_AUTOLOAD;
54
55 /* Damn, can't handle this case properly with iptables... */
56 if (conf->from_offset > conf->to_offset)
57 return false;
58 if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
59 return false;
60 if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
61 return false;
62 if (match->revision == 1) {
63 if (conf->u.v1.flags &
64 ~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT))
65 return false;
66 if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
67 flags |= TS_IGNORECASE;
68 }
69 ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
70 GFP_KERNEL, flags);
71 if (IS_ERR(ts_conf))
72 return false;
73
74 conf->config = ts_conf;
75
76 return true;
77}
78
79static void string_mt_destroy(const struct xt_match *match, void *matchinfo)
80{
81 textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
82}
83
84static struct xt_match string_mt_reg[] __read_mostly = {
85 {
86 .name = "string",
87 .revision = 0,
88 .family = AF_INET,
89 .checkentry = string_mt_check,
90 .match = string_mt,
91 .destroy = string_mt_destroy,
92 .matchsize = sizeof(struct xt_string_info),
93 .me = THIS_MODULE
94 },
95 {
96 .name = "string",
97 .revision = 1,
98 .family = AF_INET,
99 .checkentry = string_mt_check,
100 .match = string_mt,
101 .destroy = string_mt_destroy,
102 .matchsize = sizeof(struct xt_string_info),
103 .me = THIS_MODULE
104 },
105 {
106 .name = "string",
107 .revision = 0,
108 .family = AF_INET6,
109 .checkentry = string_mt_check,
110 .match = string_mt,
111 .destroy = string_mt_destroy,
112 .matchsize = sizeof(struct xt_string_info),
113 .me = THIS_MODULE
114 },
115 {
116 .name = "string",
117 .revision = 1,
118 .family = AF_INET6,
119 .checkentry = string_mt_check,
120 .match = string_mt,
121 .destroy = string_mt_destroy,
122 .matchsize = sizeof(struct xt_string_info),
123 .me = THIS_MODULE
124 },
125};
126
127static int __init string_mt_init(void)
128{
129 return xt_register_matches(string_mt_reg, ARRAY_SIZE(string_mt_reg));
130}
131
132static void __exit string_mt_exit(void)
133{
134 xt_unregister_matches(string_mt_reg, ARRAY_SIZE(string_mt_reg));
135}
136
137module_init(string_mt_init);
138module_exit(string_mt_exit);