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/* String matching match for iptables
*
* (C) 2005 Pablo Neira Ayuso <pablo@eurodev.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_string.h>
#include <linux/textsearch.h>
MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");
MODULE_DESCRIPTION("IP tables string match module");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_string");
MODULE_ALIAS("ip6t_string");
static int match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const struct xt_match *match,
const void *matchinfo,
int offset,
unsigned int protoff,
int *hotdrop)
{
const struct xt_string_info *conf = matchinfo;
struct ts_state state;
memset(&state, 0, sizeof(struct ts_state));
return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
conf->to_offset, conf->config, &state)
!= UINT_MAX) ^ conf->invert;
}
#define STRING_TEXT_PRIV(m) ((struct xt_string_info *) m)
static int checkentry(const char *tablename,
const void *ip,
const struct xt_match *match,
void *matchinfo,
unsigned int matchsize,
unsigned int hook_mask)
{
struct xt_string_info *conf = matchinfo;
struct ts_config *ts_conf;
/* Damn, can't handle this case properly with iptables... */
if (conf->from_offset > conf->to_offset)
return 0;
if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
return 0;
if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
return 0;
ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
GFP_KERNEL, TS_AUTOLOAD);
if (IS_ERR(ts_conf))
return 0;
conf->config = ts_conf;
return 1;
}
static void destroy(const struct xt_match *match, void *matchinfo,
unsigned int matchsize)
{
textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
}
static struct xt_match string_match = {
.name = "string",
.match = match,
.matchsize = sizeof(struct xt_string_info),
.checkentry = checkentry,
.destroy = destroy,
.family = AF_INET,
.me = THIS_MODULE
};
static struct xt_match string6_match = {
.name = "string",
.match = match,
.matchsize = sizeof(struct xt_string_info),
.checkentry = checkentry,
.destroy = destroy,
.family = AF_INET6,
.me = THIS_MODULE
};
static int __init xt_string_init(void)
{
int ret;
ret = xt_register_match(&string_match);
if (ret)
return ret;
ret = xt_register_match(&string6_match);
if (ret)
xt_unregister_match(&string_match);
return ret;
}
static void __exit xt_string_fini(void)
{
xt_unregister_match(&string_match);
xt_unregister_match(&string6_match);
}
module_init(xt_string_init);
module_exit(xt_string_fini);
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