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 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 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(priv, skb, &state); 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 }; 100 101 static int broute_table_init(struct net *net) 102 { 103 return ebt_register_table(net, &broute_table, &ebt_ops_broute); 104 } 105 106 static void __net_exit broute_net_pre_exit(struct net *net) 107 { 108 ebt_unregister_table_pre_exit(net, "broute"); 109 } 110 111 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 }; 120 121 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 } 136 137 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