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
19static 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
34static 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
46static 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
53static 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
74static int frame_nat_table_init(struct net *net)
75{
76 return ebt_register_table(net, table: &frame_nat, ops: ebt_ops_nat);
77}
78
79static void __net_exit frame_nat_net_pre_exit(struct net *net)
80{
81 ebt_unregister_table_pre_exit(net, tablename: "nat");
82}
83
84static void __net_exit frame_nat_net_exit(struct net *net)
85{
86 ebt_unregister_table(net, tablename: "nat");
87}
88
89static struct pernet_operations frame_nat_net_ops = {
90 .exit = frame_nat_net_exit,
91 .pre_exit = frame_nat_net_pre_exit,
92};
93
94static int __init ebtable_nat_init(void)
95{
96 int ret = ebt_register_template(t: &frame_nat, table_init: 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(t: &frame_nat);
104 return ret;
105 }
106
107 return ret;
108}
109
110static void __exit ebtable_nat_fini(void)
111{
112 unregister_pernet_subsys(&frame_nat_net_ops);
113 ebt_unregister_template(t: &frame_nat);
114}
115
116module_init(ebtable_nat_init);
117module_exit(ebtable_nat_fini);
118MODULE_LICENSE("GPL");
119MODULE_DESCRIPTION("ebtables legacy stateless nat table");
120

source code of linux/net/bridge/netfilter/ebtable_nat.c