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 .name = "PREROUTING",
20 .policy = EBT_ACCEPT,
21 },
22 {
23 .name = "OUTPUT",
24 .policy = EBT_ACCEPT,
25 },
26 {
27 .name = "POSTROUTING",
28 .policy = EBT_ACCEPT,
29 }
30 };
31
32 static struct ebt_replace_kernel initial_table = {
33 .name = "nat",
34 .valid_hooks = NAT_VALID_HOOKS,
35 .entries_size = 3 * sizeof(struct ebt_entries),
36 .hook_entry = {
37 [NF_BR_PRE_ROUTING] = &initial_chains[0],
38 [NF_BR_LOCAL_OUT] = &initial_chains[1],
39 [NF_BR_POST_ROUTING] = &initial_chains[2],
40 },
41 .entries = (char *)initial_chains,
42 };
43
check(const struct ebt_table_info * info,unsigned int valid_hooks)44 static int check(const struct ebt_table_info *info, unsigned int valid_hooks)
45 {
46 if (valid_hooks & ~NAT_VALID_HOOKS)
47 return -EINVAL;
48 return 0;
49 }
50
51 static struct ebt_table frame_nat = {
52 .name = "nat",
53 .table = &initial_table,
54 .valid_hooks = NAT_VALID_HOOKS,
55 .check = check,
56 .me = THIS_MODULE,
57 };
58
59 static unsigned int
ebt_nat_in(const struct nf_hook_ops * ops,struct sk_buff * skb,const struct net_device * in,const struct net_device * out,int (* okfn)(struct sk_buff *))60 ebt_nat_in(const struct nf_hook_ops *ops, struct sk_buff *skb,
61 const struct net_device *in, const struct net_device *out,
62 int (*okfn)(struct sk_buff *))
63 {
64 return ebt_do_table(ops->hooknum, skb, in, out,
65 dev_net(in)->xt.frame_nat);
66 }
67
68 static unsigned int
ebt_nat_out(const struct nf_hook_ops * ops,struct sk_buff * skb,const struct net_device * in,const struct net_device * out,int (* okfn)(struct sk_buff *))69 ebt_nat_out(const struct nf_hook_ops *ops, struct sk_buff *skb,
70 const struct net_device *in, const struct net_device *out,
71 int (*okfn)(struct sk_buff *))
72 {
73 return ebt_do_table(ops->hooknum, skb, in, out,
74 dev_net(out)->xt.frame_nat);
75 }
76
77 static struct nf_hook_ops ebt_ops_nat[] __read_mostly = {
78 {
79 .hook = ebt_nat_out,
80 .owner = THIS_MODULE,
81 .pf = NFPROTO_BRIDGE,
82 .hooknum = NF_BR_LOCAL_OUT,
83 .priority = NF_BR_PRI_NAT_DST_OTHER,
84 },
85 {
86 .hook = ebt_nat_out,
87 .owner = THIS_MODULE,
88 .pf = NFPROTO_BRIDGE,
89 .hooknum = NF_BR_POST_ROUTING,
90 .priority = NF_BR_PRI_NAT_SRC,
91 },
92 {
93 .hook = ebt_nat_in,
94 .owner = THIS_MODULE,
95 .pf = NFPROTO_BRIDGE,
96 .hooknum = NF_BR_PRE_ROUTING,
97 .priority = NF_BR_PRI_NAT_DST_BRIDGED,
98 },
99 };
100
frame_nat_net_init(struct net * net)101 static int __net_init frame_nat_net_init(struct net *net)
102 {
103 net->xt.frame_nat = ebt_register_table(net, &frame_nat);
104 return PTR_ERR_OR_ZERO(net->xt.frame_nat);
105 }
106
frame_nat_net_exit(struct net * net)107 static void __net_exit frame_nat_net_exit(struct net *net)
108 {
109 ebt_unregister_table(net, net->xt.frame_nat);
110 }
111
112 static struct pernet_operations frame_nat_net_ops = {
113 .init = frame_nat_net_init,
114 .exit = frame_nat_net_exit,
115 };
116
ebtable_nat_init(void)117 static int __init ebtable_nat_init(void)
118 {
119 int ret;
120
121 ret = register_pernet_subsys(&frame_nat_net_ops);
122 if (ret < 0)
123 return ret;
124 ret = nf_register_hooks(ebt_ops_nat, ARRAY_SIZE(ebt_ops_nat));
125 if (ret < 0)
126 unregister_pernet_subsys(&frame_nat_net_ops);
127 return ret;
128 }
129
ebtable_nat_fini(void)130 static void __exit ebtable_nat_fini(void)
131 {
132 nf_unregister_hooks(ebt_ops_nat, ARRAY_SIZE(ebt_ops_nat));
133 unregister_pernet_subsys(&frame_nat_net_ops);
134 }
135
136 module_init(ebtable_nat_init);
137 module_exit(ebtable_nat_fini);
138 MODULE_LICENSE("GPL");
139