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, priv);
70 if (ret != NF_DROP)
71 return ret;
72
73 /* DROP in ebtables -t broute means that the
74 * skb should be routed, not bridged.
75 * This is awkward, but can't be changed for compatibility
76 * reasons.
77 *
78 * We map DROP to ACCEPT and set the ->br_netfilter_broute flag.
79 */
80 BR_INPUT_SKB_CB(skb)->br_netfilter_broute = 1;
81
82 /* undo PACKET_HOST mangling done in br_input in case the dst
83 * address matches the logical bridge but not the port.
84 */
85 dest = eth_hdr(skb)->h_dest;
86 if (skb->pkt_type == PACKET_HOST &&
87 !ether_addr_equal(skb->dev->dev_addr, dest) &&
88 ether_addr_equal(p->br->dev->dev_addr, dest))
89 skb->pkt_type = PACKET_OTHERHOST;
90
91 return NF_ACCEPT;
92 }
93
94 static const struct nf_hook_ops ebt_ops_broute = {
95 .hook = ebt_broute,
96 .pf = NFPROTO_BRIDGE,
97 .hooknum = NF_BR_PRE_ROUTING,
98 .priority = NF_BR_PRI_FIRST,
99 };
100
broute_table_init(struct net * net)101 static int broute_table_init(struct net *net)
102 {
103 return ebt_register_table(net, &broute_table, &ebt_ops_broute);
104 }
105
broute_net_pre_exit(struct net * net)106 static void __net_exit broute_net_pre_exit(struct net *net)
107 {
108 ebt_unregister_table_pre_exit(net, "broute");
109 }
110
broute_net_exit(struct net * net)111 static void __net_exit broute_net_exit(struct net *net)
112 {
113 ebt_unregister_table(net, "broute");
114 }
115
116 static struct pernet_operations broute_net_ops = {
117 .exit = broute_net_exit,
118 .pre_exit = broute_net_pre_exit,
119 };
120
ebtable_broute_init(void)121 static int __init ebtable_broute_init(void)
122 {
123 int ret = ebt_register_template(&broute_table, broute_table_init);
124
125 if (ret)
126 return ret;
127
128 ret = register_pernet_subsys(&broute_net_ops);
129 if (ret) {
130 ebt_unregister_template(&broute_table);
131 return ret;
132 }
133
134 return 0;
135 }
136
ebtable_broute_fini(void)137 static void __exit ebtable_broute_fini(void)
138 {
139 unregister_pernet_subsys(&broute_net_ops);
140 ebt_unregister_template(&broute_table);
141 }
142
143 module_init(ebtable_broute_init);
144 module_exit(ebtable_broute_fini);
145 MODULE_LICENSE("GPL");
146
