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  */
24 static struct ebt_entries initial_chain = {
25 	.name		= "BROUTING",
26 	.policy		= EBT_ACCEPT,
27 };
28 
29 static 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 
39 static 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 
ebt_broute(void * priv,struct sk_buff * skb,const struct nf_hook_state * s)46 static 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 
86 static 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 
broute_table_init(struct net * net)93 static int broute_table_init(struct net *net)
94 {
95 	return ebt_register_table(net, &broute_table, &ebt_ops_broute);
96 }
97 
broute_net_pre_exit(struct net * net)98 static void __net_exit broute_net_pre_exit(struct net *net)
99 {
100 	ebt_unregister_table_pre_exit(net, "broute");
101 }
102 
broute_net_exit(struct net * net)103 static void __net_exit broute_net_exit(struct net *net)
104 {
105 	ebt_unregister_table(net, "broute");
106 }
107 
108 static struct pernet_operations broute_net_ops = {
109 	.exit = broute_net_exit,
110 	.pre_exit = broute_net_pre_exit,
111 };
112 
ebtable_broute_init(void)113 static 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 
ebtable_broute_fini(void)129 static void __exit ebtable_broute_fini(void)
130 {
131 	unregister_pernet_subsys(&broute_net_ops);
132 	ebt_unregister_template(&broute_table);
133 }
134 
135 module_init(ebtable_broute_init);
136 module_exit(ebtable_broute_fini);
137 MODULE_LICENSE("GPL");
138