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10#include <linux/gfp.h>
11#include <linux/init.h>
12#include <linux/module.h>
13#include <linux/kernel.h>
14#include <linux/skbuff.h>
15#include <linux/netfilter/x_tables.h>
16#include <linux/netfilter/xt_string.h>
17#include <linux/textsearch.h>
18
19MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>");
20MODULE_DESCRIPTION("Xtables: string-based matching");
21MODULE_LICENSE("GPL");
22MODULE_ALIAS("ipt_string");
23MODULE_ALIAS("ip6t_string");
24
25static bool
26string_mt(const struct sk_buff *skb, struct xt_action_param *par)
27{
28 const struct xt_string_info *conf = par->matchinfo;
29 struct ts_state state;
30 bool invert;
31
32 memset(&state, 0, sizeof(struct ts_state));
33 invert = conf->u.v1.flags & XT_STRING_FLAG_INVERT;
34
35 return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
36 conf->to_offset, conf->config, &state)
37 != UINT_MAX) ^ invert;
38}
39
40#define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))
41
42static int string_mt_check(const struct xt_mtchk_param *par)
43{
44 struct xt_string_info *conf = par->matchinfo;
45 struct ts_config *ts_conf;
46 int flags = TS_AUTOLOAD;
47
48
49 if (conf->from_offset > conf->to_offset)
50 return -EINVAL;
51 if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
52 return -EINVAL;
53 if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
54 return -EINVAL;
55 if (conf->u.v1.flags &
56 ~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT))
57 return -EINVAL;
58 if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
59 flags |= TS_IGNORECASE;
60 ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
61 GFP_KERNEL, flags);
62 if (IS_ERR(ts_conf))
63 return PTR_ERR(ts_conf);
64
65 conf->config = ts_conf;
66 return 0;
67}
68
69static void string_mt_destroy(const struct xt_mtdtor_param *par)
70{
71 textsearch_destroy(STRING_TEXT_PRIV(par->matchinfo)->config);
72}
73
74static struct xt_match xt_string_mt_reg __read_mostly = {
75 .name = "string",
76 .revision = 1,
77 .family = NFPROTO_UNSPEC,
78 .checkentry = string_mt_check,
79 .match = string_mt,
80 .destroy = string_mt_destroy,
81 .matchsize = sizeof(struct xt_string_info),
82 .me = THIS_MODULE,
83};
84
85static int __init string_mt_init(void)
86{
87 return xt_register_match(&xt_string_mt_reg);
88}
89
90static void __exit string_mt_exit(void)
91{
92 xt_unregister_match(&xt_string_mt_reg);
93}
94
95module_init(string_mt_init);
96module_exit(string_mt_exit);
97