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/net/netfilter/xt_string.c

http://github.com/mirrors/linux
C | 93 lines | 73 code | 14 blank | 6 comment | 8 complexity | 848cc5b82611d5706f383569197ddd9a MD5 | raw file
 1// SPDX-License-Identifier: GPL-2.0-only
 2/* String matching match for iptables
 3 *
 4 * (C) 2005 Pablo Neira Ayuso <pablo@eurodev.net>
 5 */
 6
 7#include <linux/gfp.h>
 8#include <linux/init.h>
 9#include <linux/module.h>
10#include <linux/kernel.h>
11#include <linux/skbuff.h>
12#include <linux/netfilter/x_tables.h>
13#include <linux/netfilter/xt_string.h>
14#include <linux/textsearch.h>
15
16MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");
17MODULE_DESCRIPTION("Xtables: string-based matching");
18MODULE_LICENSE("GPL");
19MODULE_ALIAS("ipt_string");
20MODULE_ALIAS("ip6t_string");
21MODULE_ALIAS("ebt_string");
22
23static bool
24string_mt(const struct sk_buff *skb, struct xt_action_param *par)
25{
26	const struct xt_string_info *conf = par->matchinfo;
27	bool invert;
28
29	invert = conf->u.v1.flags & XT_STRING_FLAG_INVERT;
30
31	return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
32			     conf->to_offset, conf->config)
33			     != UINT_MAX) ^ invert;
34}
35
36#define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))
37
38static int string_mt_check(const struct xt_mtchk_param *par)
39{
40	struct xt_string_info *conf = par->matchinfo;
41	struct ts_config *ts_conf;
42	int flags = TS_AUTOLOAD;
43
44	/* Damn, can't handle this case properly with iptables... */
45	if (conf->from_offset > conf->to_offset)
46		return -EINVAL;
47	if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
48		return -EINVAL;
49	if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
50		return -EINVAL;
51	if (conf->u.v1.flags &
52	    ~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT))
53		return -EINVAL;
54	if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
55		flags |= TS_IGNORECASE;
56	ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
57				     GFP_KERNEL, flags);
58	if (IS_ERR(ts_conf))
59		return PTR_ERR(ts_conf);
60
61	conf->config = ts_conf;
62	return 0;
63}
64
65static void string_mt_destroy(const struct xt_mtdtor_param *par)
66{
67	textsearch_destroy(STRING_TEXT_PRIV(par->matchinfo)->config);
68}
69
70static struct xt_match xt_string_mt_reg __read_mostly = {
71	.name       = "string",
72	.revision   = 1,
73	.family     = NFPROTO_UNSPEC,
74	.checkentry = string_mt_check,
75	.match      = string_mt,
76	.destroy    = string_mt_destroy,
77	.matchsize  = sizeof(struct xt_string_info),
78	.usersize   = offsetof(struct xt_string_info, config),
79	.me         = THIS_MODULE,
80};
81
82static int __init string_mt_init(void)
83{
84	return xt_register_match(&xt_string_mt_reg);
85}
86
87static void __exit string_mt_exit(void)
88{
89	xt_unregister_match(&xt_string_mt_reg);
90}
91
92module_init(string_mt_init);
93module_exit(string_mt_exit);