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7567662b PNA |
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> | |
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14 | #include <linux/netfilter/x_tables.h> |
15 | #include <linux/netfilter/xt_string.h> | |
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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"); | |
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21 | MODULE_ALIAS("ipt_string"); |
22 | MODULE_ALIAS("ip6t_string"); | |
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23 | |
24 | static int match(const struct sk_buff *skb, | |
25 | const struct net_device *in, | |
26 | const struct net_device *out, | |
c4986734 | 27 | const struct xt_match *match, |
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28 | const void *matchinfo, |
29 | int offset, | |
2e4e6a17 | 30 | unsigned int protoff, |
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31 | int *hotdrop) |
32 | { | |
3e72b2fe | 33 | const struct xt_string_info *conf = matchinfo; |
7567662b | 34 | struct ts_state state; |
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35 | |
36 | memset(&state, 0, sizeof(struct ts_state)); | |
37 | ||
38 | return (skb_find_text((struct sk_buff *)skb, conf->from_offset, | |
39 | conf->to_offset, conf->config, &state) | |
40 | != UINT_MAX) && !conf->invert; | |
41 | } | |
42 | ||
2e4e6a17 | 43 | #define STRING_TEXT_PRIV(m) ((struct xt_string_info *) m) |
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44 | |
45 | static int checkentry(const char *tablename, | |
2e4e6a17 | 46 | const void *ip, |
c4986734 | 47 | const struct xt_match *match, |
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48 | void *matchinfo, |
49 | unsigned int matchsize, | |
50 | unsigned int hook_mask) | |
51 | { | |
2e4e6a17 | 52 | struct xt_string_info *conf = matchinfo; |
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53 | struct ts_config *ts_conf; |
54 | ||
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55 | /* Damn, can't handle this case properly with iptables... */ |
56 | if (conf->from_offset > conf->to_offset) | |
57 | return 0; | |
58 | ||
59 | ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen, | |
60 | GFP_KERNEL, TS_AUTOLOAD); | |
61 | if (IS_ERR(ts_conf)) | |
62 | return 0; | |
63 | ||
64 | conf->config = ts_conf; | |
65 | ||
66 | return 1; | |
67 | } | |
68 | ||
c4986734 PM |
69 | static void destroy(const struct xt_match *match, void *matchinfo, |
70 | unsigned int matchsize) | |
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71 | { |
72 | textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config); | |
73 | } | |
74 | ||
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75 | static struct xt_match string_match = { |
76 | .name = "string", | |
77 | .match = match, | |
5d04bff0 | 78 | .matchsize = sizeof(struct xt_string_info), |
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79 | .checkentry = checkentry, |
80 | .destroy = destroy, | |
a45049c5 | 81 | .family = AF_INET, |
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82 | .me = THIS_MODULE |
83 | }; | |
84 | static struct xt_match string6_match = { | |
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85 | .name = "string", |
86 | .match = match, | |
5d04bff0 | 87 | .matchsize = sizeof(struct xt_string_info), |
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88 | .checkentry = checkentry, |
89 | .destroy = destroy, | |
a45049c5 | 90 | .family = AF_INET6, |
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91 | .me = THIS_MODULE |
92 | }; | |
93 | ||
65b4b4e8 | 94 | static int __init xt_string_init(void) |
7567662b | 95 | { |
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96 | int ret; |
97 | ||
a45049c5 | 98 | ret = xt_register_match(&string_match); |
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99 | if (ret) |
100 | return ret; | |
a45049c5 | 101 | ret = xt_register_match(&string6_match); |
2e4e6a17 | 102 | if (ret) |
a45049c5 | 103 | xt_unregister_match(&string_match); |
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104 | |
105 | return ret; | |
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106 | } |
107 | ||
65b4b4e8 | 108 | static void __exit xt_string_fini(void) |
7567662b | 109 | { |
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110 | xt_unregister_match(&string_match); |
111 | xt_unregister_match(&string6_match); | |
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112 | } |
113 | ||
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114 | module_init(xt_string_init); |
115 | module_exit(xt_string_fini); |