/* 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 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) { textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config); } static struct xt_match xt_string_match[] = { { .name = "string", .family = AF_INET, .checkentry = checkentry, .match = match, .destroy = destroy, .matchsize = sizeof(struct xt_string_info), .me = THIS_MODULE }, { .name = "string", .family = AF_INET6, .checkentry = checkentry, .match = match, .destroy = destroy, .matchsize = sizeof(struct xt_string_info), .me = THIS_MODULE }, }; static int __init xt_string_init(void) { return xt_register_matches(xt_string_match, ARRAY_SIZE(xt_string_match)); } static void __exit xt_string_fini(void) { xt_unregister_matches(xt_string_match, ARRAY_SIZE(xt_string_match)); } module_init(xt_string_init); module_exit(xt_string_fini);