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
ebt_dnat_tg(struct sk_buff * skb,const struct xt_action_param * par)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
ebt_dnat_tg_check(const struct xt_tgchk_param * par)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
ebt_dnat_init(void)93 static int __init ebt_dnat_init(void)
94 {
95 return xt_register_target(&ebt_dnat_tg_reg);
96 }
97
ebt_dnat_fini(void)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