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