1// SPDX-License-Identifier: GPL-2.0-only
2/* Kernel module to match the bridge port in and
3 * out device for IP packets coming into contact with a bridge. */
4
5/* (C) 2001-2003 Bart De Schuymer <bdschuym@pandora.be>
6 */
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/if.h>
10#include <linux/module.h>
11#include <linux/skbuff.h>
12#include <linux/netfilter_bridge.h>
13#include <linux/netfilter/x_tables.h>
14#include <uapi/linux/netfilter/xt_physdev.h>
15
16MODULE_LICENSE("GPL");
17MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
18MODULE_DESCRIPTION("Xtables: Bridge physical device match");
19MODULE_ALIAS("ipt_physdev");
20MODULE_ALIAS("ip6t_physdev");
21
22
23static bool
24physdev_mt(const struct sk_buff *skb, struct xt_action_param *par)
25{
26	const struct xt_physdev_info *info = par->matchinfo;
27	const struct net_device *physdev;
28	unsigned long ret;
29	const char *indev, *outdev;
30
31	/* Not a bridged IP packet or no info available yet:
32	 * LOCAL_OUT/mangle and LOCAL_OUT/nat don't know if
33	 * the destination device will be a bridge. */
34	if (!nf_bridge_info_exists(skb)) {
35		/* Return MATCH if the invert flags of the used options are on */
36		if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
37		    !(info->invert & XT_PHYSDEV_OP_BRIDGED))
38			return false;
39		if ((info->bitmask & XT_PHYSDEV_OP_ISIN) &&
40		    !(info->invert & XT_PHYSDEV_OP_ISIN))
41			return false;
42		if ((info->bitmask & XT_PHYSDEV_OP_ISOUT) &&
43		    !(info->invert & XT_PHYSDEV_OP_ISOUT))
44			return false;
45		if ((info->bitmask & XT_PHYSDEV_OP_IN) &&
46		    !(info->invert & XT_PHYSDEV_OP_IN))
47			return false;
48		if ((info->bitmask & XT_PHYSDEV_OP_OUT) &&
49		    !(info->invert & XT_PHYSDEV_OP_OUT))
50			return false;
51		return true;
52	}
53
54	physdev = nf_bridge_get_physoutdev(skb);
55	outdev = physdev ? physdev->name : NULL;
56
57	/* This only makes sense in the FORWARD and POSTROUTING chains */
58	if ((info->bitmask & XT_PHYSDEV_OP_BRIDGED) &&
59	    (!!outdev ^ !(info->invert & XT_PHYSDEV_OP_BRIDGED)))
60		return false;
61
62	physdev = nf_bridge_get_physindev(skb, xt_net(par));
63	indev = physdev ? physdev->name : NULL;
64
65	if ((info->bitmask & XT_PHYSDEV_OP_ISIN &&
66	    (!indev ^ !!(info->invert & XT_PHYSDEV_OP_ISIN))) ||
67	    (info->bitmask & XT_PHYSDEV_OP_ISOUT &&
68	    (!outdev ^ !!(info->invert & XT_PHYSDEV_OP_ISOUT))))
69		return false;
70
71	if (!(info->bitmask & XT_PHYSDEV_OP_IN))
72		goto match_outdev;
73
74	if (indev) {
75		ret = ifname_compare_aligned(indev, info->physindev,
76					     info->in_mask);
77
78		if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN))
79			return false;
80	}
81
82match_outdev:
83	if (!(info->bitmask & XT_PHYSDEV_OP_OUT))
84		return true;
85
86	if (!outdev)
87		return false;
88
89	ret = ifname_compare_aligned(outdev, info->physoutdev, info->out_mask);
90
91	return (!!ret ^ !(info->invert & XT_PHYSDEV_OP_OUT));
92}
93
94static int physdev_mt_check(const struct xt_mtchk_param *par)
95{
96	const struct xt_physdev_info *info = par->matchinfo;
97	static bool brnf_probed __read_mostly;
98
99	if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
100	    info->bitmask & ~XT_PHYSDEV_OP_MASK)
101		return -EINVAL;
102	if (info->bitmask & (XT_PHYSDEV_OP_OUT | XT_PHYSDEV_OP_ISOUT) &&
103	    (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
104	     info->invert & XT_PHYSDEV_OP_BRIDGED) &&
105	    par->hook_mask & (1 << NF_INET_LOCAL_OUT)) {
106		pr_info_ratelimited("--physdev-out and --physdev-is-out only supported in the FORWARD and POSTROUTING chains with bridged traffic\n");
107		return -EINVAL;
108	}
109
110	if (!brnf_probed) {
111		brnf_probed = true;
112		request_module("br_netfilter");
113	}
114
115	return 0;
116}
117
118static struct xt_match physdev_mt_reg __read_mostly = {
119	.name       = "physdev",
120	.revision   = 0,
121	.family     = NFPROTO_UNSPEC,
122	.checkentry = physdev_mt_check,
123	.match      = physdev_mt,
124	.matchsize  = sizeof(struct xt_physdev_info),
125	.me         = THIS_MODULE,
126};
127
128static int __init physdev_mt_init(void)
129{
130	return xt_register_match(&physdev_mt_reg);
131}
132
133static void __exit physdev_mt_exit(void)
134{
135	xt_unregister_match(&physdev_mt_reg);
136}
137
138module_init(physdev_mt_init);
139module_exit(physdev_mt_exit);
140