1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *  ebtable_broute
4 *
5 *	Authors:
6 *	Bart De Schuymer <bdschuym@pandora.be>
7 *
8 *  April, 2002
9 *
10 *  This table lets you choose between routing and bridging for frames
11 *  entering on a bridge enslaved nic. This table is traversed before any
12 *  other ebtables table. See net/bridge/br_input.c.
13 */
14
15#include <linux/netfilter_bridge/ebtables.h>
16#include <linux/module.h>
17#include <linux/if_bridge.h>
18
19#include "../br_private.h"
20
21/* EBT_ACCEPT means the frame will be bridged
22 * EBT_DROP means the frame will be routed
23 */
24static struct ebt_entries initial_chain = {
25	.name		= "BROUTING",
26	.policy		= EBT_ACCEPT,
27};
28
29static struct ebt_replace_kernel initial_table = {
30	.name		= "broute",
31	.valid_hooks	= 1 << NF_BR_BROUTING,
32	.entries_size	= sizeof(struct ebt_entries),
33	.hook_entry	= {
34		[NF_BR_BROUTING]	= &initial_chain,
35	},
36	.entries	= (char *)&initial_chain,
37};
38
39static const struct ebt_table broute_table = {
40	.name		= "broute",
41	.table		= &initial_table,
42	.valid_hooks	= 1 << NF_BR_BROUTING,
43	.me		= THIS_MODULE,
44};
45
46static unsigned int ebt_broute(void *priv, struct sk_buff *skb,
47			       const struct nf_hook_state *s)
48{
49	struct net_bridge_port *p = br_port_get_rcu(skb->dev);
50	struct nf_hook_state state;
51	unsigned char *dest;
52	int ret;
53
54	if (!p || p->state != BR_STATE_FORWARDING)
55		return NF_ACCEPT;
56
57	nf_hook_state_init(&state, NF_BR_BROUTING,
58			   NFPROTO_BRIDGE, s->in, NULL, NULL,
59			   s->net, NULL);
60
61	ret = ebt_do_table(priv, skb, &state);
62	if (ret != NF_DROP)
63		return ret;
64
65	/* DROP in ebtables -t broute means that the
66	 * skb should be routed, not bridged.
67	 * This is awkward, but can't be changed for compatibility
68	 * reasons.
69	 *
70	 * We map DROP to ACCEPT and set the ->br_netfilter_broute flag.
71	 */
72	BR_INPUT_SKB_CB(skb)->br_netfilter_broute = 1;
73
74	/* undo PACKET_HOST mangling done in br_input in case the dst
75	 * address matches the logical bridge but not the port.
76	 */
77	dest = eth_hdr(skb)->h_dest;
78	if (skb->pkt_type == PACKET_HOST &&
79	    !ether_addr_equal(skb->dev->dev_addr, dest) &&
80	     ether_addr_equal(p->br->dev->dev_addr, dest))
81		skb->pkt_type = PACKET_OTHERHOST;
82
83	return NF_ACCEPT;
84}
85
86static const struct nf_hook_ops ebt_ops_broute = {
87	.hook		= ebt_broute,
88	.pf		= NFPROTO_BRIDGE,
89	.hooknum	= NF_BR_PRE_ROUTING,
90	.priority	= NF_BR_PRI_FIRST,
91};
92
93static int broute_table_init(struct net *net)
94{
95	return ebt_register_table(net, &broute_table, &ebt_ops_broute);
96}
97
98static void __net_exit broute_net_pre_exit(struct net *net)
99{
100	ebt_unregister_table_pre_exit(net, "broute");
101}
102
103static void __net_exit broute_net_exit(struct net *net)
104{
105	ebt_unregister_table(net, "broute");
106}
107
108static struct pernet_operations broute_net_ops = {
109	.exit = broute_net_exit,
110	.pre_exit = broute_net_pre_exit,
111};
112
113static int __init ebtable_broute_init(void)
114{
115	int ret = ebt_register_template(&broute_table, broute_table_init);
116
117	if (ret)
118		return ret;
119
120	ret = register_pernet_subsys(&broute_net_ops);
121	if (ret) {
122		ebt_unregister_template(&broute_table);
123		return ret;
124	}
125
126	return 0;
127}
128
129static void __exit ebtable_broute_fini(void)
130{
131	unregister_pernet_subsys(&broute_net_ops);
132	ebt_unregister_template(&broute_table);
133}
134
135module_init(ebtable_broute_init);
136module_exit(ebtable_broute_fini);
137MODULE_LICENSE("GPL");
138MODULE_DESCRIPTION("Force packets to be routed instead of bridged");
139