1/*
2 * Xtables module to match the process control group.
3 *
4 * Might be used to implement individual "per-application" firewall
5 * policies in contrast to global policies based on control groups.
6 * Matching is based upon processes tagged to net_cls' classid marker.
7 *
8 * (C) 2013 Daniel Borkmann <dborkman@redhat.com>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14
15#include <linux/skbuff.h>
16#include <linux/module.h>
17#include <linux/netfilter/x_tables.h>
18#include <linux/netfilter/xt_cgroup.h>
19#include <net/sock.h>
20
21MODULE_LICENSE("GPL");
22MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
23MODULE_DESCRIPTION("Xtables: process control group matching");
24MODULE_ALIAS("ipt_cgroup");
25MODULE_ALIAS("ip6t_cgroup");
26
27static int cgroup_mt_check(const struct xt_mtchk_param *par)
28{
29	struct xt_cgroup_info *info = par->matchinfo;
30
31	if (info->invert & ~1)
32		return -EINVAL;
33
34	return 0;
35}
36
37static bool
38cgroup_mt(const struct sk_buff *skb, struct xt_action_param *par)
39{
40	const struct xt_cgroup_info *info = par->matchinfo;
41
42	if (skb->sk == NULL || !sk_fullsock(skb->sk))
43		return false;
44
45	return (info->id == skb->sk->sk_classid) ^ info->invert;
46}
47
48static struct xt_match cgroup_mt_reg __read_mostly = {
49	.name       = "cgroup",
50	.revision   = 0,
51	.family     = NFPROTO_UNSPEC,
52	.checkentry = cgroup_mt_check,
53	.match      = cgroup_mt,
54	.matchsize  = sizeof(struct xt_cgroup_info),
55	.me         = THIS_MODULE,
56	.hooks      = (1 << NF_INET_LOCAL_OUT) |
57		      (1 << NF_INET_POST_ROUTING) |
58		      (1 << NF_INET_LOCAL_IN),
59};
60
61static int __init cgroup_mt_init(void)
62{
63	return xt_register_match(&cgroup_mt_reg);
64}
65
66static void __exit cgroup_mt_exit(void)
67{
68	xt_unregister_match(&cgroup_mt_reg);
69}
70
71module_init(cgroup_mt_init);
72module_exit(cgroup_mt_exit);
73