1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* String matching match for iptables |
3 | * |
4 | * (C) 2005 Pablo Neira Ayuso <pablo@eurodev.net> |
5 | */ |
6 | |
7 | #include <linux/gfp.h> |
8 | #include <linux/init.h> |
9 | #include <linux/module.h> |
10 | #include <linux/kernel.h> |
11 | #include <linux/skbuff.h> |
12 | #include <linux/netfilter/x_tables.h> |
13 | #include <linux/netfilter/xt_string.h> |
14 | #include <linux/textsearch.h> |
15 | |
16 | MODULE_AUTHOR("Pablo Neira Ayuso <pablo@eurodev.net>" ); |
17 | MODULE_DESCRIPTION("Xtables: string-based matching" ); |
18 | MODULE_LICENSE("GPL" ); |
19 | MODULE_ALIAS("ipt_string" ); |
20 | MODULE_ALIAS("ip6t_string" ); |
21 | MODULE_ALIAS("ebt_string" ); |
22 | |
23 | static bool |
24 | string_mt(const struct sk_buff *skb, struct xt_action_param *par) |
25 | { |
26 | const struct xt_string_info *conf = par->matchinfo; |
27 | bool invert; |
28 | |
29 | invert = conf->u.v1.flags & XT_STRING_FLAG_INVERT; |
30 | |
31 | return (skb_find_text(skb: (struct sk_buff *)skb, from: conf->from_offset, |
32 | to: conf->to_offset, config: conf->config) |
33 | != UINT_MAX) ^ invert; |
34 | } |
35 | |
36 | #define STRING_TEXT_PRIV(m) ((struct xt_string_info *)(m)) |
37 | |
38 | static int string_mt_check(const struct xt_mtchk_param *par) |
39 | { |
40 | struct xt_string_info *conf = par->matchinfo; |
41 | struct ts_config *ts_conf; |
42 | int flags = TS_AUTOLOAD; |
43 | |
44 | /* Damn, can't handle this case properly with iptables... */ |
45 | if (conf->from_offset > conf->to_offset) |
46 | return -EINVAL; |
47 | if (conf->algo[XT_STRING_MAX_ALGO_NAME_SIZE - 1] != '\0') |
48 | return -EINVAL; |
49 | if (conf->patlen > XT_STRING_MAX_PATTERN_SIZE) |
50 | return -EINVAL; |
51 | if (conf->u.v1.flags & |
52 | ~(XT_STRING_FLAG_IGNORECASE | XT_STRING_FLAG_INVERT)) |
53 | return -EINVAL; |
54 | if (conf->u.v1.flags & XT_STRING_FLAG_IGNORECASE) |
55 | flags |= TS_IGNORECASE; |
56 | ts_conf = textsearch_prepare(conf->algo, conf->pattern, conf->patlen, |
57 | GFP_KERNEL, flags); |
58 | if (IS_ERR(ptr: ts_conf)) |
59 | return PTR_ERR(ptr: ts_conf); |
60 | |
61 | conf->config = ts_conf; |
62 | return 0; |
63 | } |
64 | |
65 | static void string_mt_destroy(const struct xt_mtdtor_param *par) |
66 | { |
67 | textsearch_destroy(STRING_TEXT_PRIV(par->matchinfo)->config); |
68 | } |
69 | |
70 | static struct xt_match xt_string_mt_reg __read_mostly = { |
71 | .name = "string" , |
72 | .revision = 1, |
73 | .family = NFPROTO_UNSPEC, |
74 | .checkentry = string_mt_check, |
75 | .match = string_mt, |
76 | .destroy = string_mt_destroy, |
77 | .matchsize = sizeof(struct xt_string_info), |
78 | .usersize = offsetof(struct xt_string_info, config), |
79 | .me = THIS_MODULE, |
80 | }; |
81 | |
82 | static int __init string_mt_init(void) |
83 | { |
84 | return xt_register_match(target: &xt_string_mt_reg); |
85 | } |
86 | |
87 | static void __exit string_mt_exit(void) |
88 | { |
89 | xt_unregister_match(target: &xt_string_mt_reg); |
90 | } |
91 | |
92 | module_init(string_mt_init); |
93 | module_exit(string_mt_exit); |
94 | |