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
16 MODULE_LICENSE("GPL");
17 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
18 MODULE_DESCRIPTION("Xtables: Bridge physical device match");
19 MODULE_ALIAS("ipt_physdev");
20 MODULE_ALIAS("ip6t_physdev");
21
22
23 static bool
physdev_mt(const struct sk_buff * skb,struct xt_action_param * par)24 physdev_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);
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
82 match_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
physdev_mt_check(const struct xt_mtchk_param * par)94 static 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
118 static 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
physdev_mt_init(void)128 static int __init physdev_mt_init(void)
129 {
130 return xt_register_match(&physdev_mt_reg);
131 }
132
physdev_mt_exit(void)133 static void __exit physdev_mt_exit(void)
134 {
135 xt_unregister_match(&physdev_mt_reg);
136 }
137
138 module_init(physdev_mt_init);
139 module_exit(physdev_mt_exit);
140