1 /*
2  *  ebtable_nat
3  *
4  *	Authors:
5  *	Bart De Schuymer <bdschuym@pandora.be>
6  *
7  *  April, 2002
8  *
9  */
10 
11 #include <linux/netfilter_bridge/ebtables.h>
12 #include <linux/module.h>
13 
14 #define NAT_VALID_HOOKS ((1 << NF_BR_PRE_ROUTING) | (1 << NF_BR_LOCAL_OUT) | \
15    (1 << NF_BR_POST_ROUTING))
16 
17 static struct ebt_entries initial_chains[] =
18 {
19 	{
20 		.name	= "PREROUTING",
21 		.policy	= EBT_ACCEPT,
22 	},
23 	{
24 		.name	= "OUTPUT",
25 		.policy	= EBT_ACCEPT,
26 	},
27 	{
28 		.name	= "POSTROUTING",
29 		.policy	= EBT_ACCEPT,
30 	}
31 };
32 
33 static struct ebt_replace_kernel initial_table =
34 {
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 struct ebt_table frame_nat =
54 {
55 	.name		= "nat",
56 	.table		= &initial_table,
57 	.valid_hooks	= NAT_VALID_HOOKS,
58 	.check		= check,
59 	.me		= THIS_MODULE,
60 };
61 
62 static unsigned int
63 ebt_nat_in(unsigned int hook, struct sk_buff *skb, const struct net_device *in
64    , const struct net_device *out, int (*okfn)(struct sk_buff *))
65 {
66 	return ebt_do_table(hook, skb, in, out, dev_net(in)->xt.frame_nat);
67 }
68 
69 static unsigned int
70 ebt_nat_out(unsigned int hook, struct sk_buff *skb, const struct net_device *in
71    , const struct net_device *out, int (*okfn)(struct sk_buff *))
72 {
73 	return ebt_do_table(hook, skb, in, out, dev_net(out)->xt.frame_nat);
74 }
75 
76 static struct nf_hook_ops ebt_ops_nat[] __read_mostly = {
77 	{
78 		.hook		= ebt_nat_out,
79 		.owner		= THIS_MODULE,
80 		.pf		= NFPROTO_BRIDGE,
81 		.hooknum	= NF_BR_LOCAL_OUT,
82 		.priority	= NF_BR_PRI_NAT_DST_OTHER,
83 	},
84 	{
85 		.hook		= ebt_nat_out,
86 		.owner		= THIS_MODULE,
87 		.pf		= NFPROTO_BRIDGE,
88 		.hooknum	= NF_BR_POST_ROUTING,
89 		.priority	= NF_BR_PRI_NAT_SRC,
90 	},
91 	{
92 		.hook		= ebt_nat_in,
93 		.owner		= THIS_MODULE,
94 		.pf		= NFPROTO_BRIDGE,
95 		.hooknum	= NF_BR_PRE_ROUTING,
96 		.priority	= NF_BR_PRI_NAT_DST_BRIDGED,
97 	},
98 };
99 
100 static int __net_init frame_nat_net_init(struct net *net)
101 {
102 	net->xt.frame_nat = ebt_register_table(net, &frame_nat);
103 	return PTR_RET(net->xt.frame_nat);
104 }
105 
106 static void __net_exit frame_nat_net_exit(struct net *net)
107 {
108 	ebt_unregister_table(net, net->xt.frame_nat);
109 }
110 
111 static struct pernet_operations frame_nat_net_ops = {
112 	.init = frame_nat_net_init,
113 	.exit = frame_nat_net_exit,
114 };
115 
116 static int __init ebtable_nat_init(void)
117 {
118 	int ret;
119 
120 	ret = register_pernet_subsys(&frame_nat_net_ops);
121 	if (ret < 0)
122 		return ret;
123 	ret = nf_register_hooks(ebt_ops_nat, ARRAY_SIZE(ebt_ops_nat));
124 	if (ret < 0)
125 		unregister_pernet_subsys(&frame_nat_net_ops);
126 	return ret;
127 }
128 
129 static void __exit ebtable_nat_fini(void)
130 {
131 	nf_unregister_hooks(ebt_ops_nat, ARRAY_SIZE(ebt_ops_nat));
132 	unregister_pernet_subsys(&frame_nat_net_ops);
133 }
134 
135 module_init(ebtable_nat_init);
136 module_exit(ebtable_nat_fini);
137 MODULE_LICENSE("GPL");
138