// SPDX-License-Identifier: GPL-2.0-only
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/* String matching match for iptables
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*
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* (C) 2005 Pablo Neira Ayuso <pablo@eurodev.net>
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*/
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#include <linux/gfp.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter/xt_string.h>
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#include <linux/textsearch.h>
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MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");
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MODULE_DESCRIPTION("Xtables: string-based matching");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("ipt_string");
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MODULE_ALIAS("ip6t_string");
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MODULE_ALIAS("ebt_string");
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static bool
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string_mt(const struct sk_buff *skb, struct xt_action_param *par)
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{
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const struct xt_string_info *conf = par->matchinfo;
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bool invert;
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invert = conf->u.v1.flags & XT_STRING_FLAG_INVERT;
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return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
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conf->to_offset, conf->config)
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!= UINT_MAX) ^ invert;
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}
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#define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))
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static int string_mt_check(const struct xt_mtchk_param *par)
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{
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struct xt_string_info *conf = par->matchinfo;
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struct ts_config *ts_conf;
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int flags = TS_AUTOLOAD;
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/* Damn, can't handle this case properly with iptables... */
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if (conf->from_offset > conf->to_offset)
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return -EINVAL;
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if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
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return -EINVAL;
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if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
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return -EINVAL;
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if (conf->u.v1.flags &
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~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT))
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return -EINVAL;
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if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
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flags |= TS_IGNORECASE;
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ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
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GFP_KERNEL, flags);
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if (IS_ERR(ts_conf))
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return PTR_ERR(ts_conf);
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conf->config = ts_conf;
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return 0;
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}
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static void string_mt_destroy(const struct xt_mtdtor_param *par)
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{
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textsearch_destroy(STRING_TEXT_PRIV(par->matchinfo)->config);
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}
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static struct xt_match xt_string_mt_reg __read_mostly = {
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.name = "string",
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.revision = 1,
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.family = NFPROTO_UNSPEC,
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.checkentry = string_mt_check,
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.match = string_mt,
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.destroy = string_mt_destroy,
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.matchsize = sizeof(struct xt_string_info),
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.usersize = offsetof(struct xt_string_info, config),
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.me = THIS_MODULE,
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};
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static int __init string_mt_init(void)
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{
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return xt_register_match(&xt_string_mt_reg);
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}
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static void __exit string_mt_exit(void)
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{
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xt_unregister_match(&xt_string_mt_reg);
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}
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module_init(string_mt_init);
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module_exit(string_mt_exit);
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