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 int check(const struct ebt_table_info *info, unsigned int valid_hooks)
47 {
48 	if (valid_hooks & ~NAT_VALID_HOOKS)
49 		return -EINVAL;
50 	return 0;
51 }
52 
53 static const struct ebt_table frame_nat = {
54 	.name		= "nat",
55 	.table		= &initial_table,
56 	.valid_hooks	= NAT_VALID_HOOKS,
57 	.check		= check,
58 	.me		= THIS_MODULE,
59 };
60 
61 static unsigned int ebt_nat_hook(void *priv, struct sk_buff *skb,
62 				 const struct nf_hook_state *state)
63 {
64 	return ebt_do_table(skb, state, priv);
65 }
66 
67 static const struct nf_hook_ops ebt_ops_nat[] = {
68 	{
69 		.hook		= ebt_nat_hook,
70 		.pf		= NFPROTO_BRIDGE,
71 		.hooknum	= NF_BR_LOCAL_OUT,
72 		.priority	= NF_BR_PRI_NAT_DST_OTHER,
73 	},
74 	{
75 		.hook		= ebt_nat_hook,
76 		.pf		= NFPROTO_BRIDGE,
77 		.hooknum	= NF_BR_POST_ROUTING,
78 		.priority	= NF_BR_PRI_NAT_SRC,
79 	},
80 	{
81 		.hook		= ebt_nat_hook,
82 		.pf		= NFPROTO_BRIDGE,
83 		.hooknum	= NF_BR_PRE_ROUTING,
84 		.priority	= NF_BR_PRI_NAT_DST_BRIDGED,
85 	},
86 };
87 
88 static int __net_init frame_nat_net_init(struct net *net)
89 {
90 	return ebt_register_table(net, &frame_nat, ebt_ops_nat);
91 }
92 
93 static void __net_exit frame_nat_net_pre_exit(struct net *net)
94 {
95 	ebt_unregister_table_pre_exit(net, "nat");
96 }
97 
98 static void __net_exit frame_nat_net_exit(struct net *net)
99 {
100 	ebt_unregister_table(net, "nat");
101 }
102 
103 static struct pernet_operations frame_nat_net_ops = {
104 	.init = frame_nat_net_init,
105 	.exit = frame_nat_net_exit,
106 	.pre_exit = frame_nat_net_pre_exit,
107 };
108 
109 static int __init ebtable_nat_init(void)
110 {
111 	return register_pernet_subsys(&frame_nat_net_ops);
112 }
113 
114 static void __exit ebtable_nat_fini(void)
115 {
116 	unregister_pernet_subsys(&frame_nat_net_ops);
117 }
118 
119 module_init(ebtable_nat_init);
120 module_exit(ebtable_nat_fini);
121 MODULE_LICENSE("GPL");
122