projects/linux·blob master · refs

175 lines · 4.7 KiB

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 <[email protected]>
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 <[email protected]>");
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_hooks(const struct xt_mtchk_param *par)
95{
96 const struct xt_physdev_info *info = par->matchinfo;
97
98 if (info->bitmask & (XT_PHYSDEV_OP_OUT | XT_PHYSDEV_OP_ISOUT) &&
99 (!(info->bitmask & XT_PHYSDEV_OP_BRIDGED) ||
100 info->invert & XT_PHYSDEV_OP_BRIDGED) &&
101 par->hook_mask & (1 << NF_INET_LOCAL_OUT)) {
102 pr_info_ratelimited("--physdev-out and --physdev-is-out only supported in the FORWARD and POSTROUTING chains with bridged traffic\n");
103 return -EINVAL;
104 }
105
106 return 0;
107}
108
109static int physdev_mt_check(const struct xt_mtchk_param *par)
110{
111 const struct xt_physdev_info *info = par->matchinfo;
112 static bool brnf_probed __read_mostly;
113
114 if (!(info->bitmask & XT_PHYSDEV_OP_MASK) ||
115 info->bitmask & ~XT_PHYSDEV_OP_MASK)
116 return -EINVAL;
117
118#define X(memb) strnlen(info->memb, sizeof(info->memb)) >= sizeof(info->memb)
119 if (info->bitmask & XT_PHYSDEV_OP_IN) {
120 if (info->physindev[0] == '\0')
121 return -EINVAL;
122 if (X(physindev))
123 return -ENAMETOOLONG;
124 }
125
126 if (info->bitmask & XT_PHYSDEV_OP_OUT) {
127 if (info->physoutdev[0] == '\0')
128 return -EINVAL;
129
130 if (X(physoutdev))
131 return -ENAMETOOLONG;
132 }
133#undef X
134
135 if (!brnf_probed) {
136 brnf_probed = true;
137 request_module("br_netfilter");
138 }
139
140 return 0;
141}
142
143static struct xt_match physdev_mt_reg[] __read_mostly = {
144 {
145 .name = "physdev",
146 .family = NFPROTO_IPV4,
147 .check_hooks = physdev_mt_check_hooks,
148 .checkentry = physdev_mt_check,
149 .match = physdev_mt,
150 .matchsize = sizeof(struct xt_physdev_info),
151 .me = THIS_MODULE,
152 },
153 {
154 .name = "physdev",
155 .family = NFPROTO_IPV6,
156 .check_hooks = physdev_mt_check_hooks,
157 .checkentry = physdev_mt_check,
158 .match = physdev_mt,
159 .matchsize = sizeof(struct xt_physdev_info),
160 .me = THIS_MODULE,
161 },
162};
163
164static int __init physdev_mt_init(void)
165{
166 return xt_register_matches(physdev_mt_reg, ARRAY_SIZE(physdev_mt_reg));
167}
168
169static void __exit physdev_mt_exit(void)
170{
171 xt_unregister_matches(physdev_mt_reg, ARRAY_SIZE(physdev_mt_reg));
172}
173
174module_init(physdev_mt_init);
175module_exit(physdev_mt_exit);