1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
4 *
5 * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
6 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
7 */
8
9#include <linux/module.h>
10#include <linux/moduleparam.h>
11#include <linux/netfilter_ipv4/ip_tables.h>
12#include <linux/slab.h>
13#include <net/ip.h>
14
15MODULE_LICENSE("GPL");
16MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
17MODULE_DESCRIPTION("iptables filter table");
18
19#define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \
20			    (1 << NF_INET_FORWARD) | \
21			    (1 << NF_INET_LOCAL_OUT))
22
23static const struct xt_table packet_filter = {
24	.name		= "filter",
25	.valid_hooks	= FILTER_VALID_HOOKS,
26	.me		= THIS_MODULE,
27	.af		= NFPROTO_IPV4,
28	.priority	= NF_IP_PRI_FILTER,
29};
30
31static struct nf_hook_ops *filter_ops __read_mostly;
32
33/* Default to forward because I got too much mail already. */
34static bool forward __read_mostly = true;
35module_param(forward, bool, 0000);
36
37static int iptable_filter_table_init(struct net *net)
38{
39	struct ipt_replace *repl;
40	int err;
41
42	repl = ipt_alloc_initial_table(&packet_filter);
43	if (repl == NULL)
44		return -ENOMEM;
45	/* Entry 1 is the FORWARD hook */
46	((struct ipt_standard *)repl->entries)[1].target.verdict =
47		forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;
48
49	err = ipt_register_table(net, &packet_filter, repl, filter_ops);
50	kfree(repl);
51	return err;
52}
53
54static int __net_init iptable_filter_net_init(struct net *net)
55{
56	if (!forward)
57		return iptable_filter_table_init(net);
58
59	return 0;
60}
61
62static void __net_exit iptable_filter_net_pre_exit(struct net *net)
63{
64	ipt_unregister_table_pre_exit(net, "filter");
65}
66
67static void __net_exit iptable_filter_net_exit(struct net *net)
68{
69	ipt_unregister_table_exit(net, "filter");
70}
71
72static struct pernet_operations iptable_filter_net_ops = {
73	.init = iptable_filter_net_init,
74	.pre_exit = iptable_filter_net_pre_exit,
75	.exit = iptable_filter_net_exit,
76};
77
78static int __init iptable_filter_init(void)
79{
80	int ret = xt_register_template(&packet_filter,
81				       iptable_filter_table_init);
82
83	if (ret < 0)
84		return ret;
85
86	filter_ops = xt_hook_ops_alloc(&packet_filter, ipt_do_table);
87	if (IS_ERR(filter_ops)) {
88		xt_unregister_template(&packet_filter);
89		return PTR_ERR(filter_ops);
90	}
91
92	ret = register_pernet_subsys(&iptable_filter_net_ops);
93	if (ret < 0) {
94		xt_unregister_template(&packet_filter);
95		kfree(filter_ops);
96		return ret;
97	}
98
99	return 0;
100}
101
102static void __exit iptable_filter_fini(void)
103{
104	unregister_pernet_subsys(&iptable_filter_net_ops);
105	xt_unregister_template(&packet_filter);
106	kfree(filter_ops);
107}
108
109module_init(iptable_filter_init);
110module_exit(iptable_filter_fini);
111