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
check(const struct ebt_table_info * info,unsigned int valid_hooks)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
ebt_nat_hook(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)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
frame_nat_table_init(struct net * net)88 static int frame_nat_table_init(struct net *net)
89 {
90 return ebt_register_table(net, &frame_nat, ebt_ops_nat);
91 }
92
frame_nat_net_pre_exit(struct net * net)93 static void __net_exit frame_nat_net_pre_exit(struct net *net)
94 {
95 ebt_unregister_table_pre_exit(net, "nat");
96 }
97
frame_nat_net_exit(struct net * net)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 .exit = frame_nat_net_exit,
105 .pre_exit = frame_nat_net_pre_exit,
106 };
107
ebtable_nat_init(void)108 static int __init ebtable_nat_init(void)
109 {
110 int ret = ebt_register_template(&frame_nat, frame_nat_table_init);
111
112 if (ret)
113 return ret;
114
115 ret = register_pernet_subsys(&frame_nat_net_ops);
116 if (ret) {
117 ebt_unregister_template(&frame_nat);
118 return ret;
119 }
120
121 return ret;
122 }
123
ebtable_nat_fini(void)124 static void __exit ebtable_nat_fini(void)
125 {
126 unregister_pernet_subsys(&frame_nat_net_ops);
127 ebt_unregister_template(&frame_nat);
128 }
129
130 module_init(ebtable_nat_init);
131 module_exit(ebtable_nat_fini);
132 MODULE_LICENSE("GPL");
133
