1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * ebt_dnat 4 * 5 * Authors: 6 * Bart De Schuymer <bdschuym@pandora.be> 7 * 8 * June, 2002 9 * 10 */ 11 #include <linux/module.h> 12 #include <net/sock.h> 13 #include "../br_private.h" 14 #include <linux/netfilter.h> 15 #include <linux/netfilter/x_tables.h> 16 #include <linux/netfilter_bridge/ebtables.h> 17 #include <linux/netfilter_bridge/ebt_nat.h> 18 19 static unsigned int 20 ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par) 21 { 22 const struct ebt_nat_info *info = par->targinfo; 23 24 if (skb_ensure_writable(skb, 0)) 25 return EBT_DROP; 26 27 ether_addr_copy(eth_hdr(skb)->h_dest, info->mac); 28 29 if (is_multicast_ether_addr(info->mac)) { 30 if (is_broadcast_ether_addr(info->mac)) 31 skb->pkt_type = PACKET_BROADCAST; 32 else 33 skb->pkt_type = PACKET_MULTICAST; 34 } else { 35 const struct net_device *dev; 36 37 switch (xt_hooknum(par)) { 38 case NF_BR_BROUTING: 39 dev = xt_in(par); 40 break; 41 case NF_BR_PRE_ROUTING: 42 dev = br_port_get_rcu(xt_in(par))->br->dev; 43 break; 44 default: 45 dev = NULL; 46 break; 47 } 48 49 if (!dev) /* NF_BR_LOCAL_OUT */ 50 return info->target; 51 52 if (ether_addr_equal(info->mac, dev->dev_addr)) 53 skb->pkt_type = PACKET_HOST; 54 else 55 skb->pkt_type = PACKET_OTHERHOST; 56 } 57 58 return info->target; 59 } 60 61 static int ebt_dnat_tg_check(const struct xt_tgchk_param *par) 62 { 63 const struct ebt_nat_info *info = par->targinfo; 64 unsigned int hook_mask; 65 66 if (BASE_CHAIN && info->target == EBT_RETURN) 67 return -EINVAL; 68 69 hook_mask = par->hook_mask & ~(1 << NF_BR_NUMHOOKS); 70 if ((strcmp(par->table, "nat") != 0 || 71 (hook_mask & ~((1 << NF_BR_PRE_ROUTING) | 72 (1 << NF_BR_LOCAL_OUT)))) && 73 (strcmp(par->table, "broute") != 0 || 74 hook_mask & ~(1 << NF_BR_BROUTING))) 75 return -EINVAL; 76 if (ebt_invalid_target(info->target)) 77 return -EINVAL; 78 return 0; 79 } 80 81 static struct xt_target ebt_dnat_tg_reg __read_mostly = { 82 .name = "dnat", 83 .revision = 0, 84 .family = NFPROTO_BRIDGE, 85 .hooks = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING) | 86 (1 << NF_BR_LOCAL_OUT) | (1 << NF_BR_BROUTING), 87 .target = ebt_dnat_tg, 88 .checkentry = ebt_dnat_tg_check, 89 .targetsize = sizeof(struct ebt_nat_info), 90 .me = THIS_MODULE, 91 }; 92 93 static int __init ebt_dnat_init(void) 94 { 95 return xt_register_target(&ebt_dnat_tg_reg); 96 } 97 98 static void __exit ebt_dnat_fini(void) 99 { 100 xt_unregister_target(&ebt_dnat_tg_reg); 101 } 102 103 module_init(ebt_dnat_init); 104 module_exit(ebt_dnat_fini); 105 MODULE_DESCRIPTION("Ebtables: Destination MAC address translation"); 106 MODULE_LICENSE("GPL"); 107