1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  ebtable_nat
4  *
5  *	Authors:
6  *	Bart De Schuymer <bdschuym@pandora.be>
7  *
8  *  April, 2002
9  *
10  */
11 
12 #include <linux/netfilter_bridge/ebtables.h>
13 #include <uapi/linux/netfilter_bridge.h>
14 #include <linux/module.h>
15 
16 #define NAT_VALID_HOOKS ((1 << NF_BR_PRE_ROUTING) | (1 << NF_BR_LOCAL_OUT) | \
17 			 (1 << NF_BR_POST_ROUTING))
18 
19 static struct ebt_entries initial_chains[] = {
20 	{
21 		.name	= "PREROUTING",
22 		.policy	= EBT_ACCEPT,
23 	},
24 	{
25 		.name	= "OUTPUT",
26 		.policy	= EBT_ACCEPT,
27 	},
28 	{
29 		.name	= "POSTROUTING",
30 		.policy	= EBT_ACCEPT,
31 	}
32 };
33 
34 static struct ebt_replace_kernel initial_table = {
35 	.name		= "nat",
36 	.valid_hooks	= NAT_VALID_HOOKS,
37 	.entries_size	= 3 * sizeof(struct ebt_entries),
38 	.hook_entry	= {
39 		[NF_BR_PRE_ROUTING]	= &initial_chains[0],
40 		[NF_BR_LOCAL_OUT]	= &initial_chains[1],
41 		[NF_BR_POST_ROUTING]	= &initial_chains[2],
42 	},
43 	.entries	= (char *)initial_chains,
44 };
45 
46 static const struct ebt_table frame_nat = {
47 	.name		= "nat",
48 	.table		= &initial_table,
49 	.valid_hooks	= NAT_VALID_HOOKS,
50 	.me		= THIS_MODULE,
51 };
52 
53 static const struct nf_hook_ops ebt_ops_nat[] = {
54 	{
55 		.hook		= ebt_do_table,
56 		.pf		= NFPROTO_BRIDGE,
57 		.hooknum	= NF_BR_LOCAL_OUT,
58 		.priority	= NF_BR_PRI_NAT_DST_OTHER,
59 	},
60 	{
61 		.hook		= ebt_do_table,
62 		.pf		= NFPROTO_BRIDGE,
63 		.hooknum	= NF_BR_POST_ROUTING,
64 		.priority	= NF_BR_PRI_NAT_SRC,
65 	},
66 	{
67 		.hook		= ebt_do_table,
68 		.pf		= NFPROTO_BRIDGE,
69 		.hooknum	= NF_BR_PRE_ROUTING,
70 		.priority	= NF_BR_PRI_NAT_DST_BRIDGED,
71 	},
72 };
73 
74 static int frame_nat_table_init(struct net *net)
75 {
76 	return ebt_register_table(net, &frame_nat, ebt_ops_nat);
77 }
78 
79 static void __net_exit frame_nat_net_pre_exit(struct net *net)
80 {
81 	ebt_unregister_table_pre_exit(net, "nat");
82 }
83 
84 static void __net_exit frame_nat_net_exit(struct net *net)
85 {
86 	ebt_unregister_table(net, "nat");
87 }
88 
89 static struct pernet_operations frame_nat_net_ops = {
90 	.exit = frame_nat_net_exit,
91 	.pre_exit = frame_nat_net_pre_exit,
92 };
93 
94 static int __init ebtable_nat_init(void)
95 {
96 	int ret = ebt_register_template(&frame_nat, frame_nat_table_init);
97 
98 	if (ret)
99 		return ret;
100 
101 	ret = register_pernet_subsys(&frame_nat_net_ops);
102 	if (ret) {
103 		ebt_unregister_template(&frame_nat);
104 		return ret;
105 	}
106 
107 	return ret;
108 }
109 
110 static void __exit ebtable_nat_fini(void)
111 {
112 	unregister_pernet_subsys(&frame_nat_net_ops);
113 	ebt_unregister_template(&frame_nat);
114 }
115 
116 module_init(ebtable_nat_init);
117 module_exit(ebtable_nat_fini);
118 MODULE_LICENSE("GPL");
119