ebt_802_3.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * 802_3
 4 *
 5 * Author:
 6 * Chris Vitale csv@bluetail.com
 7 *
 8 * May 2003
 9 *
10 */
11#include <linux/module.h>
12#include <linux/netfilter/x_tables.h>
13#include <linux/netfilter_bridge/ebtables.h>
14#include <linux/skbuff.h>
15#include <uapi/linux/netfilter_bridge/ebt_802_3.h>
16
17static struct ebt_802_3_hdr *ebt_802_3_hdr(const struct sk_buff *skb)
18{
19	return (struct ebt_802_3_hdr *)skb_mac_header(skb);
20}
21
22static bool
23ebt_802_3_mt(const struct sk_buff *skb, struct xt_action_param *par)
24{
25	const struct ebt_802_3_info *info = par->matchinfo;
26	const struct ebt_802_3_hdr *hdr = ebt_802_3_hdr(skb);
27	__be16 type = hdr->llc.ui.ctrl & IS_UI ? hdr->llc.ui.type : hdr->llc.ni.type;
28
29	if (info->bitmask & EBT_802_3_SAP) {
30		if (NF_INVF(info, EBT_802_3_SAP, info->sap != hdr->llc.ui.ssap))
31			return false;
32		if (NF_INVF(info, EBT_802_3_SAP, info->sap != hdr->llc.ui.dsap))
33			return false;
34	}
35
36	if (info->bitmask & EBT_802_3_TYPE) {
37		if (!(hdr->llc.ui.dsap == CHECK_TYPE && hdr->llc.ui.ssap == CHECK_TYPE))
38			return false;
39		if (NF_INVF(info, EBT_802_3_TYPE, info->type != type))
40			return false;
41	}
42
43	return true;
44}
45
46static int ebt_802_3_mt_check(const struct xt_mtchk_param *par)
47{
48	const struct ebt_802_3_info *info = par->matchinfo;
49
50	if (info->bitmask & ~EBT_802_3_MASK || info->invflags & ~EBT_802_3_MASK)
51		return -EINVAL;
52
53	return 0;
54}
55
56static struct xt_match ebt_802_3_mt_reg __read_mostly = {
57	.name		= "802_3",
58	.revision	= 0,
59	.family		= NFPROTO_BRIDGE,
60	.match		= ebt_802_3_mt,
61	.checkentry	= ebt_802_3_mt_check,
62	.matchsize	= sizeof(struct ebt_802_3_info),
63	.me		= THIS_MODULE,
64};
65
66static int __init ebt_802_3_init(void)
67{
68	return xt_register_match(&ebt_802_3_mt_reg);
69}
70
71static void __exit ebt_802_3_fini(void)
72{
73	xt_unregister_match(&ebt_802_3_mt_reg);
74}
75
76module_init(ebt_802_3_init);
77module_exit(ebt_802_3_fini);
78MODULE_DESCRIPTION("Ebtables: DSAP/SSAP field and SNAP type matching");
79MODULE_LICENSE("GPL");