ebtable_nat.c

  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, &frame_nat, 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, "nat");
 82}
 83
 84static void __net_exit frame_nat_net_exit(struct net *net)
 85{
 86	ebt_unregister_table(net, "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(&frame_nat, 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(&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(&frame_nat);
114}
115
116module_init(ebtable_nat_init);
117module_exit(ebtable_nat_fini);
118MODULE_LICENSE("GPL");
119MODULE_DESCRIPTION("ebtables legacy stateless nat table");