1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  ebt_redirect
4  *
5  *	Authors:
6  *	Bart De Schuymer <bdschuym@pandora.be>
7  *
8  *  April, 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_redirect.h>
18 
19 static unsigned int
20 ebt_redirect_tg(struct sk_buff *skb, const struct xt_action_param *par)
21 {
22 	const struct ebt_redirect_info *info = par->targinfo;
23 
24 	if (skb_ensure_writable(skb, 0))
25 		return EBT_DROP;
26 
27 	if (xt_hooknum(par) != NF_BR_BROUTING)
28 		/* rcu_read_lock()ed by nf_hook_thresh */
29 		ether_addr_copy(eth_hdr(skb)->h_dest,
30 				br_port_get_rcu(xt_in(par))->br->dev->dev_addr);
31 	else
32 		ether_addr_copy(eth_hdr(skb)->h_dest, xt_in(par)->dev_addr);
33 	skb->pkt_type = PACKET_HOST;
34 	return info->target;
35 }
36 
37 static int ebt_redirect_tg_check(const struct xt_tgchk_param *par)
38 {
39 	const struct ebt_redirect_info *info = par->targinfo;
40 	unsigned int hook_mask;
41 
42 	if (BASE_CHAIN && info->target == EBT_RETURN)
43 		return -EINVAL;
44 
45 	hook_mask = par->hook_mask & ~(1 << NF_BR_NUMHOOKS);
46 	if ((strcmp(par->table, "nat") != 0 ||
47 	    hook_mask & ~(1 << NF_BR_PRE_ROUTING)) &&
48 	    (strcmp(par->table, "broute") != 0 ||
49 	    hook_mask & ~(1 << NF_BR_BROUTING)))
50 		return -EINVAL;
51 	if (ebt_invalid_target(info->target))
52 		return -EINVAL;
53 	return 0;
54 }
55 
56 static struct xt_target ebt_redirect_tg_reg __read_mostly = {
57 	.name		= "redirect",
58 	.revision	= 0,
59 	.family		= NFPROTO_BRIDGE,
60 	.hooks		= (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING) |
61 			  (1 << NF_BR_BROUTING),
62 	.target		= ebt_redirect_tg,
63 	.checkentry	= ebt_redirect_tg_check,
64 	.targetsize	= sizeof(struct ebt_redirect_info),
65 	.me		= THIS_MODULE,
66 };
67 
68 static int __init ebt_redirect_init(void)
69 {
70 	return xt_register_target(&ebt_redirect_tg_reg);
71 }
72 
73 static void __exit ebt_redirect_fini(void)
74 {
75 	xt_unregister_target(&ebt_redirect_tg_reg);
76 }
77 
78 module_init(ebt_redirect_init);
79 module_exit(ebt_redirect_fini);
80 MODULE_DESCRIPTION("Ebtables: Packet redirection to localhost");
81 MODULE_LICENSE("GPL");
82