Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 1 | /* String matching match for iptables |
| 2 | * |
| 3 | * (C) 2005 Pablo Neira Ayuso <pablo@eurodev.net> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License version 2 as |
| 7 | * published by the Free Software Foundation. |
| 8 | */ |
| 9 | |
| 10 | #include <linux/init.h> |
| 11 | #include <linux/module.h> |
| 12 | #include <linux/kernel.h> |
| 13 | #include <linux/skbuff.h> |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 14 | #include <linux/netfilter/x_tables.h> |
| 15 | #include <linux/netfilter/xt_string.h> |
Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 16 | #include <linux/textsearch.h> |
| 17 | |
| 18 | MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>"); |
| 19 | MODULE_DESCRIPTION("IP tables string match module"); |
| 20 | MODULE_LICENSE("GPL"); |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 21 | MODULE_ALIAS("ipt_string"); |
| 22 | MODULE_ALIAS("ip6t_string"); |
Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 23 | |
| 24 | static int match(const struct sk_buff *skb, |
| 25 | const struct net_device *in, |
| 26 | const struct net_device *out, |
| 27 | const void *matchinfo, |
| 28 | int offset, |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 29 | unsigned int protoff, |
Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 30 | int *hotdrop) |
| 31 | { |
| 32 | struct ts_state state; |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 33 | struct xt_string_info *conf = (struct xt_string_info *) matchinfo; |
Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 34 | |
| 35 | memset(&state, 0, sizeof(struct ts_state)); |
| 36 | |
| 37 | return (skb_find_text((struct sk_buff *)skb, conf->from_offset, |
| 38 | conf->to_offset, conf->config, &state) |
| 39 | != UINT_MAX) && !conf->invert; |
| 40 | } |
| 41 | |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 42 | #define STRING_TEXT_PRIV(m) ((struct xt_string_info *) m) |
Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 43 | |
| 44 | static int checkentry(const char *tablename, |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 45 | const void *ip, |
Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 46 | void *matchinfo, |
| 47 | unsigned int matchsize, |
| 48 | unsigned int hook_mask) |
| 49 | { |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 50 | struct xt_string_info *conf = matchinfo; |
Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 51 | struct ts_config *ts_conf; |
| 52 | |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 53 | if (matchsize != XT_ALIGN(sizeof(struct xt_string_info))) |
Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 54 | return 0; |
| 55 | |
| 56 | /* Damn, can't handle this case properly with iptables... */ |
| 57 | if (conf->from_offset > conf->to_offset) |
| 58 | return 0; |
| 59 | |
| 60 | ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen, |
| 61 | GFP_KERNEL, TS_AUTOLOAD); |
| 62 | if (IS_ERR(ts_conf)) |
| 63 | return 0; |
| 64 | |
| 65 | conf->config = ts_conf; |
| 66 | |
| 67 | return 1; |
| 68 | } |
| 69 | |
| 70 | static void destroy(void *matchinfo, unsigned int matchsize) |
| 71 | { |
| 72 | textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config); |
| 73 | } |
| 74 | |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 75 | static struct xt_match string_match = { |
| 76 | .name = "string", |
| 77 | .match = match, |
| 78 | .checkentry = checkentry, |
| 79 | .destroy = destroy, |
| 80 | .me = THIS_MODULE |
| 81 | }; |
| 82 | static struct xt_match string6_match = { |
Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 83 | .name = "string", |
| 84 | .match = match, |
| 85 | .checkentry = checkentry, |
| 86 | .destroy = destroy, |
| 87 | .me = THIS_MODULE |
| 88 | }; |
| 89 | |
| 90 | static int __init init(void) |
| 91 | { |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 92 | int ret; |
| 93 | |
| 94 | ret = xt_register_match(AF_INET, &string_match); |
| 95 | if (ret) |
| 96 | return ret; |
| 97 | ret = xt_register_match(AF_INET6, &string6_match); |
| 98 | if (ret) |
| 99 | xt_unregister_match(AF_INET, &string_match); |
| 100 | |
| 101 | return ret; |
Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 102 | } |
| 103 | |
| 104 | static void __exit fini(void) |
| 105 | { |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 106 | xt_unregister_match(AF_INET, &string_match); |
| 107 | xt_unregister_match(AF_INET6, &string6_match); |
Pablo Neira Ayuso | 7567662 | 2005-08-21 23:30:34 -0700 | [diff] [blame] | 108 | } |
| 109 | |
| 110 | module_init(init); |
| 111 | module_exit(fini); |