Merge branch 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus
[linux-2.6] / net / netfilter / xt_string.c
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>
14 #include <linux/netfilter/x_tables.h>
15 #include <linux/netfilter/xt_string.h>
16 #include <linux/textsearch.h>
17
18 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");
19 MODULE_DESCRIPTION("Xtables: string-based matching");
20 MODULE_LICENSE("GPL");
21 MODULE_ALIAS("ipt_string");
22 MODULE_ALIAS("ip6t_string");
23
24 static bool
25 string_mt(const struct sk_buff *skb, const struct net_device *in,
26           const struct net_device *out, const struct xt_match *match,
27           const void *matchinfo, int offset, unsigned int protoff,
28           bool *hotdrop)
29 {
30         const struct xt_string_info *conf = matchinfo;
31         struct ts_state state;
32         int invert;
33
34         memset(&state, 0, sizeof(struct ts_state));
35
36         invert = (match->revision == 0 ? conf->u.v0.invert :
37                                     conf->u.v1.flags & XT_STRING_FLAG_INVERT);
38
39         return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
40                              conf->to_offset, conf->config, &state)
41                              != UINT_MAX) ^ invert;
42 }
43
44 #define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))
45
46 static bool
47 string_mt_check(const char *tablename, const void *ip,
48                 const struct xt_match *match, void *matchinfo,
49                 unsigned int hook_mask)
50 {
51         struct xt_string_info *conf = matchinfo;
52         struct ts_config *ts_conf;
53         int flags = TS_AUTOLOAD;
54
55         /* Damn, can't handle this case properly with iptables... */
56         if (conf->from_offset > conf->to_offset)
57                 return false;
58         if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
59                 return false;
60         if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
61                 return false;
62         if (match->revision == 1) {
63                 if (conf->u.v1.flags &
64                     ~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT))
65                         return false;
66                 if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
67                         flags |= TS_IGNORECASE;
68         }
69         ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
70                                      GFP_KERNEL, flags);
71         if (IS_ERR(ts_conf))
72                 return false;
73
74         conf->config = ts_conf;
75
76         return true;
77 }
78
79 static void string_mt_destroy(const struct xt_match *match, void *matchinfo)
80 {
81         textsearch_destroy(STRING_TEXT_PRIV(matchinfo)->config);
82 }
83
84 static struct xt_match string_mt_reg[] __read_mostly = {
85         {
86                 .name           = "string",
87                 .revision       = 0,
88                 .family         = AF_INET,
89                 .checkentry     = string_mt_check,
90                 .match          = string_mt,
91                 .destroy        = string_mt_destroy,
92                 .matchsize      = sizeof(struct xt_string_info),
93                 .me             = THIS_MODULE
94         },
95         {
96                 .name           = "string",
97                 .revision       = 1,
98                 .family         = AF_INET,
99                 .checkentry     = string_mt_check,
100                 .match          = string_mt,
101                 .destroy        = string_mt_destroy,
102                 .matchsize      = sizeof(struct xt_string_info),
103                 .me             = THIS_MODULE
104         },
105         {
106                 .name           = "string",
107                 .revision       = 0,
108                 .family         = AF_INET6,
109                 .checkentry     = string_mt_check,
110                 .match          = string_mt,
111                 .destroy        = string_mt_destroy,
112                 .matchsize      = sizeof(struct xt_string_info),
113                 .me             = THIS_MODULE
114         },
115         {
116                 .name           = "string",
117                 .revision       = 1,
118                 .family         = AF_INET6,
119                 .checkentry     = string_mt_check,
120                 .match          = string_mt,
121                 .destroy        = string_mt_destroy,
122                 .matchsize      = sizeof(struct xt_string_info),
123                 .me             = THIS_MODULE
124         },
125 };
126
127 static int __init string_mt_init(void)
128 {
129         return xt_register_matches(string_mt_reg, ARRAY_SIZE(string_mt_reg));
130 }
131
132 static void __exit string_mt_exit(void)
133 {
134         xt_unregister_matches(string_mt_reg, ARRAY_SIZE(string_mt_reg));
135 }
136
137 module_init(string_mt_init);
138 module_exit(string_mt_exit);