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
33 memset(&state, 0, sizeof(struct ts_state));
34
35 return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
36 conf->to_offset, conf->config, &state)
37 != UINT_MAX) ^ conf->invert;
38}
39
40#define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))
41
42static bool
43string_mt_check(const char *tablename, const void *ip,
44 const struct xt_match *match, void *matchinfo,
45 unsigned int hook_mask)
46{
47 struct xt_string_info *conf = matchinfo;
48 struct ts_config *ts_conf;
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 ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
58 GFP_KERNEL, TS_AUTOLOAD);
59 if (IS_ERR(ts_conf))
60 return false;
61
62 conf->config = ts_conf;
63
64 return true;
65}
66
67static void string_mt_destroy(const struct xt_match *match, void *matchinfo)
68{
69 textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
70}
71
72static struct xt_match string_mt_reg[] __read_mostly = {
73 {
74 .name = "string",
75 .family = AF_INET,
76 .checkentry = string_mt_check,
77 .match = string_mt,
78 .destroy = string_mt_destroy,
79 .matchsize = sizeof(struct xt_string_info),
80 .me = THIS_MODULE
81 },
82 {
83 .name = "string",
84 .family = AF_INET6,
85 .checkentry = string_mt_check,
86 .match = string_mt,
87 .destroy = string_mt_destroy,
88 .matchsize = sizeof(struct xt_string_info),
89 .me = THIS_MODULE
90 },
91};
92
93static int __init string_mt_init(void)
94{
95 return xt_register_matches(string_mt_reg, ARRAY_SIZE(string_mt_reg));
96}
97
98static void __exit string_mt_exit(void)
99{
100 xt_unregister_matches(string_mt_reg, ARRAY_SIZE(string_mt_reg));
101}
102
103module_init(string_mt_init);
104module_exit(string_mt_exit);