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 | |
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(dev: 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(p: &state, NF_BR_BROUTING, |
58 | pf: NFPROTO_BRIDGE, indev: s->in, NULL, NULL, |
59 | net: s->net, NULL); |
60 | |
61 | ret = ebt_do_table(priv, skb, state: &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(addr1: skb->dev->dev_addr, addr2: dest) && |
80 | ether_addr_equal(addr1: p->br->dev->dev_addr, addr2: 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 | |
93 | static int broute_table_init(struct net *net) |
94 | { |
95 | return ebt_register_table(net, table: &broute_table, ops: &ebt_ops_broute); |
96 | } |
97 | |
98 | static void __net_exit broute_net_pre_exit(struct net *net) |
99 | { |
100 | ebt_unregister_table_pre_exit(net, tablename: "broute" ); |
101 | } |
102 | |
103 | static void __net_exit broute_net_exit(struct net *net) |
104 | { |
105 | ebt_unregister_table(net, tablename: "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 | |
113 | static int __init ebtable_broute_init(void) |
114 | { |
115 | int ret = ebt_register_template(t: &broute_table, table_init: 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(t: &broute_table); |
123 | return ret; |
124 | } |
125 | |
126 | return 0; |
127 | } |
128 | |
129 | static void __exit ebtable_broute_fini(void) |
130 | { |
131 | unregister_pernet_subsys(&broute_net_ops); |
132 | ebt_unregister_template(t: &broute_table); |
133 | } |
134 | |
135 | module_init(ebtable_broute_init); |
136 | module_exit(ebtable_broute_fini); |
137 | MODULE_LICENSE("GPL" ); |
138 | MODULE_DESCRIPTION("Force packets to be routed instead of bridged" ); |
139 | |