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/gfp.h>
11#include <linux/init.h>
12#include <linux/module.h>
13#include <linux/kernel.h>
14#include <linux/skbuff.h>
15#include <linux/netfilter/x_tables.h>
16#include <linux/netfilter/xt_string.h>
17#include <linux/textsearch.h>
18
19MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");
20MODULE_DESCRIPTION("Xtables: string-based matching");
21MODULE_LICENSE("GPL");
22MODULE_ALIAS("ipt_string");
23MODULE_ALIAS("ip6t_string");
24
25static bool
26string_mt(const struct sk_buff *skb, const struct xt_match_param *par)
27{
28 const struct xt_string_info *conf = par->matchinfo;
29 struct ts_state state;
30 int invert;
31
32 memset(&state, 0, sizeof(struct ts_state));
33
34 invert = (par->match->revision == 0 ? conf->u.v0.invert :
35 conf->u.v1.flags & XT_STRING_FLAG_INVERT);
36
37 return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
38 conf->to_offset, conf->config, &state)
39 != UINT_MAX) ^ invert;
40}
41
42#define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))
43
44static bool string_mt_check(const struct xt_mtchk_param *par)
45{
46 struct xt_string_info *conf = par->matchinfo;
47 struct ts_config *ts_conf;
48 int flags = TS_AUTOLOAD;
49
50 /* Damn, can't handle this case properly with iptables... */
51 if (conf->from_offset > conf->to_offset)
52 return false;
53 if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
54 return false;
55 if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
56 return false;
57 if (par->match->revision == 1) {
58 if (conf->u.v1.flags &
59 ~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT))
60 return false;
61 if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
62 flags |= TS_IGNORECASE;
63 }
64 ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
65 GFP_KERNEL, flags);
66 if (IS_ERR(ts_conf))
67 return false;
68
69 conf->config = ts_conf;
70
71 return true;
72}
73
74static void string_mt_destroy(const struct xt_mtdtor_param *par)
75{
76 textsearch_destroy(STRING_TEXT_PRIV(par->matchinfo)->config);
77}
78
79static struct xt_match xt_string_mt_reg[] __read_mostly = {
80 {
81 .name = "string",
82 .revision = 0,
83 .family = NFPROTO_UNSPEC,
84 .checkentry = string_mt_check,
85 .match = string_mt,
86 .destroy = string_mt_destroy,
87 .matchsize = sizeof(struct xt_string_info),
88 .me = THIS_MODULE
89 },
90 {
91 .name = "string",
92 .revision = 1,
93 .family = NFPROTO_UNSPEC,
94 .checkentry = string_mt_check,
95 .match = string_mt,
96 .destroy = string_mt_destroy,
97 .matchsize = sizeof(struct xt_string_info),
98 .me = THIS_MODULE
99 },
100};
101
102static int __init string_mt_init(void)
103{
104 return xt_register_matches(xt_string_mt_reg,
105 ARRAY_SIZE(xt_string_mt_reg));
106}
107
108static void __exit string_mt_exit(void)
109{
110 xt_unregister_matches(xt_string_mt_reg, ARRAY_SIZE(xt_string_mt_reg));
111}
112
113module_init(string_mt_init);
114module_exit(string_mt_exit);