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
15 MODULE_LICENSE("GPL");
16 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
17 MODULE_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 static int __net_init iptable_filter_table_init(struct net *net);
23
24 static const struct xt_table packet_filter = {
25 .name = "filter",
26 .valid_hooks = FILTER_VALID_HOOKS,
27 .me = THIS_MODULE,
28 .af = NFPROTO_IPV4,
29 .priority = NF_IP_PRI_FILTER,
30 .table_init = iptable_filter_table_init,
31 };
32
33 static unsigned int
iptable_filter_hook(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)34 iptable_filter_hook(void *priv, struct sk_buff *skb,
35 const struct nf_hook_state *state)
36 {
37 return ipt_do_table(skb, state, state->net->ipv4.iptable_filter);
38 }
39
40 static struct nf_hook_ops *filter_ops __read_mostly;
41
42 /* Default to forward because I got too much mail already. */
43 static bool forward __read_mostly = true;
44 module_param(forward, bool, 0000);
45
iptable_filter_table_init(struct net * net)46 static int __net_init iptable_filter_table_init(struct net *net)
47 {
48 struct ipt_replace *repl;
49 int err;
50
51 if (net->ipv4.iptable_filter)
52 return 0;
53
54 repl = ipt_alloc_initial_table(&packet_filter);
55 if (repl == NULL)
56 return -ENOMEM;
57 /* Entry 1 is the FORWARD hook */
58 ((struct ipt_standard *)repl->entries)[1].target.verdict =
59 forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;
60
61 err = ipt_register_table(net, &packet_filter, repl, filter_ops,
62 &net->ipv4.iptable_filter);
63 kfree(repl);
64 return err;
65 }
66
iptable_filter_net_init(struct net * net)67 static int __net_init iptable_filter_net_init(struct net *net)
68 {
69 if (net == &init_net || !forward)
70 return iptable_filter_table_init(net);
71
72 return 0;
73 }
74
iptable_filter_net_pre_exit(struct net * net)75 static void __net_exit iptable_filter_net_pre_exit(struct net *net)
76 {
77 if (net->ipv4.iptable_filter)
78 ipt_unregister_table_pre_exit(net, net->ipv4.iptable_filter,
79 filter_ops);
80 }
81
iptable_filter_net_exit(struct net * net)82 static void __net_exit iptable_filter_net_exit(struct net *net)
83 {
84 if (!net->ipv4.iptable_filter)
85 return;
86 ipt_unregister_table_exit(net, net->ipv4.iptable_filter);
87 net->ipv4.iptable_filter = NULL;
88 }
89
90 static struct pernet_operations iptable_filter_net_ops = {
91 .init = iptable_filter_net_init,
92 .pre_exit = iptable_filter_net_pre_exit,
93 .exit = iptable_filter_net_exit,
94 };
95
iptable_filter_init(void)96 static int __init iptable_filter_init(void)
97 {
98 int ret;
99
100 filter_ops = xt_hook_ops_alloc(&packet_filter, iptable_filter_hook);
101 if (IS_ERR(filter_ops))
102 return PTR_ERR(filter_ops);
103
104 ret = register_pernet_subsys(&iptable_filter_net_ops);
105 if (ret < 0)
106 kfree(filter_ops);
107
108 return ret;
109 }
110
iptable_filter_fini(void)111 static void __exit iptable_filter_fini(void)
112 {
113 unregister_pernet_subsys(&iptable_filter_net_ops);
114 kfree(filter_ops);
115 }
116
117 module_init(iptable_filter_init);
118 module_exit(iptable_filter_fini);
119