tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/* iptables module to match on related connections */
2/*
3 * (C) 2001 Martin Josefsson <gandalf@wlug.westbo.se>
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/module.h>
11#include <linux/skbuff.h>
12#include <linux/netfilter.h>
13#include <net/netfilter/nf_conntrack.h>
14#include <net/netfilter/nf_conntrack_core.h>
15#include <net/netfilter/nf_conntrack_helper.h>
16#include <linux/netfilter/x_tables.h>
17#include <linux/netfilter/xt_helper.h>
18
19MODULE_LICENSE("GPL");
20MODULE_AUTHOR("Martin Josefsson <gandalf@netfilter.org>");
21MODULE_DESCRIPTION("iptables helper match module");
22MODULE_ALIAS("ipt_helper");
23MODULE_ALIAS("ip6t_helper");
24
25
26static bool
27match(const struct sk_buff *skb,
28 const struct net_device *in,
29 const struct net_device *out,
30 const struct xt_match *match,
31 const void *matchinfo,
32 int offset,
33 unsigned int protoff,
34 bool *hotdrop)
35{
36 const struct xt_helper_info *info = matchinfo;
37 const struct nf_conn *ct;
38 const struct nf_conn_help *master_help;
39 const struct nf_conntrack_helper *helper;
40 enum ip_conntrack_info ctinfo;
41 bool ret = info->invert;
42
43 ct = nf_ct_get(skb, &ctinfo);
44 if (!ct || !ct->master)
45 return ret;
46
47 master_help = nfct_help(ct->master);
48 if (!master_help)
49 return ret;
50
51 /* rcu_read_lock()ed by nf_hook_slow */
52 helper = rcu_dereference(master_help->helper);
53 if (!helper)
54 return ret;
55
56 if (info->name[0] == '\0')
57 ret = !ret;
58 else
59 ret ^= !strncmp(master_help->helper->name, info->name,
60 strlen(master_help->helper->name));
61 return ret;
62}
63
64static bool check(const char *tablename,
65 const void *inf,
66 const struct xt_match *match,
67 void *matchinfo,
68 unsigned int hook_mask)
69{
70 struct xt_helper_info *info = matchinfo;
71
72 if (nf_ct_l3proto_try_module_get(match->family) < 0) {
73 printk(KERN_WARNING "can't load conntrack support for "
74 "proto=%d\n", match->family);
75 return false;
76 }
77 info->name[29] = '\0';
78 return true;
79}
80
81static void
82destroy(const struct xt_match *match, void *matchinfo)
83{
84 nf_ct_l3proto_module_put(match->family);
85}
86
87static struct xt_match xt_helper_match[] __read_mostly = {
88 {
89 .name = "helper",
90 .family = AF_INET,
91 .checkentry = check,
92 .match = match,
93 .destroy = destroy,
94 .matchsize = sizeof(struct xt_helper_info),
95 .me = THIS_MODULE,
96 },
97 {
98 .name = "helper",
99 .family = AF_INET6,
100 .checkentry = check,
101 .match = match,
102 .destroy = destroy,
103 .matchsize = sizeof(struct xt_helper_info),
104 .me = THIS_MODULE,
105 },
106};
107
108static int __init xt_helper_init(void)
109{
110 return xt_register_matches(xt_helper_match,
111 ARRAY_SIZE(xt_helper_match));
112}
113
114static void __exit xt_helper_fini(void)
115{
116 xt_unregister_matches(xt_helper_match, ARRAY_SIZE(xt_helper_match));
117}
118
119module_init(xt_helper_init);
120module_exit(xt_helper_fini);
121