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
check(const struct ebt_table_info * info,unsigned int valid_hooks)39 static int check(const struct ebt_table_info *info, unsigned int valid_hooks)
40 {
41 if (valid_hooks & ~(1 << NF_BR_BROUTING))
42 return -EINVAL;
43 return 0;
44 }
45
46 static const struct ebt_table broute_table = {
47 .name = "broute",
48 .table = &initial_table,
49 .valid_hooks = 1 << NF_BR_BROUTING,
50 .check = check,
51 .me = THIS_MODULE,
52 };
53
ebt_broute(void * priv,struct sk_buff * skb,const struct nf_hook_state * s)54 static unsigned int ebt_broute(void *priv, struct sk_buff *skb,
55 const struct nf_hook_state *s)
56 {
57 struct net_bridge_port *p = br_port_get_rcu(skb->dev);
58 struct nf_hook_state state;
59 unsigned char *dest;
60 int ret;
61
62 if (!p || p->state != BR_STATE_FORWARDING)
63 return NF_ACCEPT;
64
65 nf_hook_state_init(&state, NF_BR_BROUTING,
66 NFPROTO_BRIDGE, s->in, NULL, NULL,
67 s->net, NULL);
68
69 ret = ebt_do_table(skb, &state, state.net->xt.broute_table);
70
71 if (ret != NF_DROP)
72 return ret;
73
74 /* DROP in ebtables -t broute means that the
75 * skb should be routed, not bridged.
76 * This is awkward, but can't be changed for compatibility
77 * reasons.
78 *
79 * We map DROP to ACCEPT and set the ->br_netfilter_broute flag.
80 */
81 BR_INPUT_SKB_CB(skb)->br_netfilter_broute = 1;
82
83 /* undo PACKET_HOST mangling done in br_input in case the dst
84 * address matches the logical bridge but not the port.
85 */
86 dest = eth_hdr(skb)->h_dest;
87 if (skb->pkt_type == PACKET_HOST &&
88 !ether_addr_equal(skb->dev->dev_addr, dest) &&
89 ether_addr_equal(p->br->dev->dev_addr, dest))
90 skb->pkt_type = PACKET_OTHERHOST;
91
92 return NF_ACCEPT;
93 }
94
95 static const struct nf_hook_ops ebt_ops_broute = {
96 .hook = ebt_broute,
97 .pf = NFPROTO_BRIDGE,
98 .hooknum = NF_BR_PRE_ROUTING,
99 .priority = NF_BR_PRI_FIRST,
100 };
101
broute_net_init(struct net * net)102 static int __net_init broute_net_init(struct net *net)
103 {
104 return ebt_register_table(net, &broute_table, &ebt_ops_broute,
105 &net->xt.broute_table);
106 }
107
broute_net_exit(struct net * net)108 static void __net_exit broute_net_exit(struct net *net)
109 {
110 ebt_unregister_table(net, net->xt.broute_table, &ebt_ops_broute);
111 }
112
113 static struct pernet_operations broute_net_ops = {
114 .init = broute_net_init,
115 .exit = broute_net_exit,
116 };
117
ebtable_broute_init(void)118 static int __init ebtable_broute_init(void)
119 {
120 return register_pernet_subsys(&broute_net_ops);
121 }
122
ebtable_broute_fini(void)123 static void __exit ebtable_broute_fini(void)
124 {
125 unregister_pernet_subsys(&broute_net_ops);
126 }
127
128 module_init(ebtable_broute_init);
129 module_exit(ebtable_broute_fini);
130 MODULE_LICENSE("GPL");
131