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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("Xtables: string-based matching");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_string");
MODULE_ALIAS("ip6t_string");
static bool
string_mt(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,
bool *hotdrop)
{
const struct xt_string_info *conf = matchinfo;
struct ts_state state;
int invert;
memset(&state, 0, sizeof(struct ts_state));
invert = (match->revision == 0 ? conf->u.v0.invert :
conf->u.v1.flags & XT_STRING_FLAG_INVERT);
return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
conf->to_offset, conf->config, &state)
!= UINT_MAX) ^ invert;
}
#define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))
static bool
string_mt_check(const char *tablename, const void *ip,
const struct xt_match *match, void *matchinfo,
unsigned int hook_mask)
{
struct xt_string_info *conf = matchinfo;
struct ts_config *ts_conf;
int flags = TS_AUTOLOAD;
/* Damn, can't handle this case properly with iptables... */
if (conf->from_offset > conf->to_offset)
return false;
if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
return false;
if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
return false;
if (match->revision == 1) {
if (conf->u.v1.flags &
~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT))
return false;
if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
flags |= TS_IGNORECASE;
}
ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
GFP_KERNEL, flags);
if (IS_ERR(ts_conf))
return false;
conf->config = ts_conf;
return true;
}
static void string_mt_destroy(const struct xt_match *match, void *matchinfo)
{
textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
}
static struct xt_match xt_string_mt_reg[] __read_mostly = {
{
.name = "string",
.revision = 0,
.family = NFPROTO_UNSPEC,
.checkentry = string_mt_check,
.match = string_mt,
.destroy = string_mt_destroy,
.matchsize = sizeof(struct xt_string_info),
.me = THIS_MODULE
},
{
.name = "string",
.revision = 1,
.family = NFPROTO_UNSPEC,
.checkentry = string_mt_check,
.match = string_mt,
.destroy = string_mt_destroy,
.matchsize = sizeof(struct xt_string_info),
.me = THIS_MODULE
},
};
static int __init string_mt_init(void)
{
return xt_register_matches(xt_string_mt_reg,
ARRAY_SIZE(xt_string_mt_reg));
}
static void __exit string_mt_exit(void)
{
xt_unregister_matches(xt_string_mt_reg, ARRAY_SIZE(xt_string_mt_reg));
}
module_init(string_mt_init);
module_exit(string_mt_exit);
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