| /* 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 xt_match_param *par) |
| { |
| const struct xt_string_info *conf = par->matchinfo; |
| struct ts_state state; |
| int invert; |
| |
| memset(&state, 0, sizeof(struct ts_state)); |
| |
| invert = (par->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 struct xt_mtchk_param *par) |
| { |
| struct xt_string_info *conf = par->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 (par->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); |