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Commit | Line | Data |
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7567662b | 1 | /* String matching match for iptables |
601e68e1 | 2 | * |
7567662b PNA |
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> | |
2e4e6a17 HW |
14 | #include <linux/netfilter/x_tables.h> |
15 | #include <linux/netfilter/xt_string.h> | |
7567662b PNA |
16 | #include <linux/textsearch.h> |
17 | ||
18 | MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>"); | |
2ae15b64 | 19 | MODULE_DESCRIPTION("Xtables: string-based matching"); |
7567662b | 20 | MODULE_LICENSE("GPL"); |
2e4e6a17 HW |
21 | MODULE_ALIAS("ipt_string"); |
22 | MODULE_ALIAS("ip6t_string"); | |
7567662b | 23 | |
d3c5ee6d | 24 | static bool |
f7108a20 | 25 | string_mt(const struct sk_buff *skb, const struct xt_match_param *par) |
7567662b | 26 | { |
f7108a20 | 27 | const struct xt_string_info *conf = par->matchinfo; |
7567662b | 28 | struct ts_state state; |
4ad3f261 | 29 | int invert; |
7567662b PNA |
30 | |
31 | memset(&state, 0, sizeof(struct ts_state)); | |
32 | ||
f7108a20 | 33 | invert = (par->match->revision == 0 ? conf->u.v0.invert : |
4ad3f261 JP |
34 | conf->u.v1.flags & XT_STRING_FLAG_INVERT); |
35 | ||
601e68e1 YH |
36 | return (skb_find_text((struct sk_buff *)skb, conf->from_offset, |
37 | conf->to_offset, conf->config, &state) | |
4ad3f261 | 38 | != UINT_MAX) ^ invert; |
7567662b PNA |
39 | } |
40 | ||
e79ec50b | 41 | #define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m)) |
7567662b | 42 | |
b0f38452 | 43 | static int string_mt_check(const struct xt_mtchk_param *par) |
7567662b | 44 | { |
9b4fce7a | 45 | struct xt_string_info *conf = par->matchinfo; |
7567662b | 46 | struct ts_config *ts_conf; |
4ad3f261 | 47 | int flags = TS_AUTOLOAD; |
7567662b | 48 | |
7567662b PNA |
49 | /* Damn, can't handle this case properly with iptables... */ |
50 | if (conf->from_offset > conf->to_offset) | |
ccb79bdc | 51 | return false; |
3ab72088 | 52 | if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0') |
ccb79bdc | 53 | return false; |
3ab72088 | 54 | if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE) |
ccb79bdc | 55 | return false; |
9b4fce7a | 56 | if (par->match->revision == 1) { |
4ad3f261 JP |
57 | if (conf->u.v1.flags & |
58 | ~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT)) | |
59 | return false; | |
60 | if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE) | |
61 | flags |= TS_IGNORECASE; | |
62 | } | |
7567662b | 63 | ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen, |
4ad3f261 | 64 | GFP_KERNEL, flags); |
7567662b | 65 | if (IS_ERR(ts_conf)) |
ccb79bdc | 66 | return false; |
7567662b PNA |
67 | |
68 | conf->config = ts_conf; | |
69 | ||
ccb79bdc | 70 | return true; |
7567662b PNA |
71 | } |
72 | ||
6be3d859 | 73 | static void string_mt_destroy(const struct xt_mtdtor_param *par) |
7567662b | 74 | { |
6be3d859 | 75 | textsearch_destroy(STRING_TEXT_PRIV(par->matchinfo)->config); |
7567662b PNA |
76 | } |
77 | ||
55b69e91 | 78 | static struct xt_match xt_string_mt_reg[] __read_mostly = { |
4470bbc7 PM |
79 | { |
80 | .name = "string", | |
4ad3f261 | 81 | .revision = 0, |
55b69e91 | 82 | .family = NFPROTO_UNSPEC, |
4ad3f261 JP |
83 | .checkentry = string_mt_check, |
84 | .match = string_mt, | |
85 | .destroy = string_mt_destroy, | |
86 | .matchsize = sizeof(struct xt_string_info), | |
87 | .me = THIS_MODULE | |
88 | }, | |
89 | { | |
90 | .name = "string", | |
91 | .revision = 1, | |
55b69e91 | 92 | .family = NFPROTO_UNSPEC, |
d3c5ee6d JE |
93 | .checkentry = string_mt_check, |
94 | .match = string_mt, | |
95 | .destroy = string_mt_destroy, | |
4470bbc7 PM |
96 | .matchsize = sizeof(struct xt_string_info), |
97 | .me = THIS_MODULE | |
98 | }, | |
7567662b PNA |
99 | }; |
100 | ||
d3c5ee6d | 101 | static int __init string_mt_init(void) |
7567662b | 102 | { |
55b69e91 JE |
103 | return xt_register_matches(xt_string_mt_reg, |
104 | ARRAY_SIZE(xt_string_mt_reg)); | |
7567662b PNA |
105 | } |
106 | ||
d3c5ee6d | 107 | static void __exit string_mt_exit(void) |
7567662b | 108 | { |
55b69e91 | 109 | xt_unregister_matches(xt_string_mt_reg, ARRAY_SIZE(xt_string_mt_reg)); |
7567662b PNA |
110 | } |
111 | ||
d3c5ee6d JE |
112 | module_init(string_mt_init); |
113 | module_exit(string_mt_exit); |