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("Xtables: Related connection matching");
22MODULE_ALIAS("ipt_helper");
23MODULE_ALIAS("ip6t_helper");
24
25
26static bool
27helper_mt(const struct sk_buff *skb, const struct xt_match_param *par)
28{
29 const struct xt_helper_info *info = par->matchinfo;
30 const struct nf_conn *ct;
31 const struct nf_conn_help *master_help;
32 const struct nf_conntrack_helper *helper;
33 enum ip_conntrack_info ctinfo;
34 bool ret = info->invert;
35
36 ct = nf_ct_get(skb, &ctinfo);
37 if (!ct || !ct->master)
38 return ret;
39
40 master_help = nfct_help(ct->master);
41 if (!master_help)
42 return ret;
43
44 /* rcu_read_lock()ed by nf_hook_slow */
45 helper = rcu_dereference(master_help->helper);
46 if (!helper)
47 return ret;
48
49 if (info->name[0] == '\0')
50 ret = !ret;
51 else
52 ret ^= !strncmp(helper->name, info->name,
53 strlen(helper->name));
54 return ret;
55}
56
57static bool helper_mt_check(const struct xt_mtchk_param *par)
58{
59 struct xt_helper_info *info = par->matchinfo;
60
61 if (nf_ct_l3proto_try_module_get(par->family) < 0) {
62 printk(KERN_WARNING "can't load conntrack support for "
63 "proto=%u\n", par->family);
64 return false;
65 }
66 info->name[29] = '\0';
67 return true;
68}
69
70static void helper_mt_destroy(const struct xt_mtdtor_param *par)
71{
72 nf_ct_l3proto_module_put(par->family);
73}
74
75static struct xt_match helper_mt_reg __read_mostly = {
76 .name = "helper",
77 .revision = 0,
78 .family = NFPROTO_UNSPEC,
79 .checkentry = helper_mt_check,
80 .match = helper_mt,
81 .destroy = helper_mt_destroy,
82 .matchsize = sizeof(struct xt_helper_info),
83 .me = THIS_MODULE,
84};
85
86static int __init helper_mt_init(void)
87{
88 return xt_register_match(&helper_mt_reg);
89}
90
91static void __exit helper_mt_exit(void)
92{
93 xt_unregister_match(&helper_mt_reg);
94}
95
96module_init(helper_mt_init);
97module_exit(helper_mt_exit);