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(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 93 static int broute_table_init(struct net *net) 94 { 95 return ebt_register_table(net, &broute_table, &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, "broute"); 101 } 102 103 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 }; 112 113 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 } 128 129 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 MODULE_DESCRIPTION("Force packets to be routed instead of bridged"); 139