| 1 | |
| 2 | |
| 3 | *
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| 4 | * (C) 2005 Pablo Neira Ayuso <[email protected]>
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| 5 |
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| 6 |
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| 7 | #include <linux/gfp.h>
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| 8 | #include <linux/init.h>
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| 9 | #include <linux/module.h>
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| 10 | #include <linux/kernel.h>
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| 11 | #include <linux/skbuff.h>
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| 12 | #include <linux/netfilter/x_tables.h>
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| 13 | #include <linux/netfilter/xt_string.h>
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| 14 | #include <linux/textsearch.h>
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| 15 |
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| 16 | MODULE_AUTHOR("Pablo Neira Ayuso <[email protected]>");
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| 17 | MODULE_DESCRIPTION("Xtables: string-based matching");
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| 18 | MODULE_LICENSE("GPL");
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| 19 | MODULE_ALIAS("ipt_string");
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| 20 | MODULE_ALIAS("ip6t_string");
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| 21 | MODULE_ALIAS("ebt_string");
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| 22 |
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| 23 | static bool
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| 24 | string_mt(const struct sk_buff *skb, struct xt_action_param *par)
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| 25 | {
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| 26 | const struct xt_string_info *conf = par->matchinfo;
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| 27 | bool invert;
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| 28 |
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| 29 | invert = conf->u.v1.flags & XT_STRING_FLAG_INVERT;
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| 30 |
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| 31 | return (skb_find_text((struct sk_buff *)skb, conf->from_offset,
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| 32 | conf->to_offset, conf->config)
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| 33 | != UINT_MAX) ^ invert;
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| 34 | }
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| 35 |
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| 36 | #define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m))
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| 37 |
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| 38 | static int string_mt_check(const struct xt_mtchk_param *par)
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| 39 | {
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| 40 | struct xt_string_info *conf = par->matchinfo;
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| 41 | struct ts_config *ts_conf;
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| 42 | int flags = TS_AUTOLOAD;
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| 43 |
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| 44 |
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| 45 | if (conf->from_offset > conf->to_offset)
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| 46 | return -EINVAL;
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| 47 | if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0')
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| 48 | return -EINVAL;
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| 49 | if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE)
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| 50 | return -EINVAL;
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| 51 | if (conf->u.v1.flags &
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| 52 | ~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT))
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| 53 | return -EINVAL;
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| 54 | if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE)
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| 55 | flags |= TS_IGNORECASE;
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| 56 | ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen,
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| 57 | GFP_KERNEL, flags);
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| 58 | if (IS_ERR(ts_conf))
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| 59 | return PTR_ERR(ts_conf);
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| 60 |
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| 61 | conf->config = ts_conf;
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| 62 | return 0;
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| 63 | }
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| 64 |
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| 65 | static void string_mt_destroy(const struct xt_mtdtor_param *par)
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| 66 | {
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| 67 | textsearch_destroy(STRING_TEXT_PRIV(par->matchinfo)->config);
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| 68 | }
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| 69 |
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| 70 | static struct xt_match xt_string_mt_reg __read_mostly = {
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| 71 | .name = "string",
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| 72 | .revision = 1,
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| 73 | .family = NFPROTO_UNSPEC,
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| 74 | .checkentry = string_mt_check,
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| 75 | .match = string_mt,
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| 76 | .destroy = string_mt_destroy,
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| 77 | .matchsize = sizeof(struct xt_string_info),
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| 78 | .usersize = offsetof(struct xt_string_info, config),
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| 79 | .me = THIS_MODULE,
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| 80 | };
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| 81 |
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| 82 | static int __init string_mt_init(void)
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| 83 | {
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| 84 | return xt_register_match(&xt_string_mt_reg);
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| 85 | }
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| 86 |
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| 87 | static void __exit string_mt_exit(void)
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| 88 | {
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| 89 | xt_unregister_match(&xt_string_mt_reg);
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| 90 | }
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| 91 |
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| 92 | module_init(string_mt_init);
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| 93 | module_exit(string_mt_exit);
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