1/* Kernel module to match MAC address parameters. */
2#include <linux/module.h>
3#include <linux/skbuff.h>
4#include <linux/if_ether.h>
5
6#include <linux/netfilter_ipv4/ipt_mac.h>
7#include <linux/netfilter_ipv4/ip_tables.h>
8
9static int
10match(const struct sk_buff *skb,
11      const struct net_device *in,
12      const struct net_device *out,
13      const void *matchinfo,
14      int offset,
15      const void *hdr,
16      u_int16_t datalen,
17      int *hotdrop)
18{
19    const struct ipt_mac_info *info = matchinfo;
20
21    /* Is mac pointer valid? */
22    return (skb->mac.raw >= skb->head
23	    && (skb->mac.raw + ETH_HLEN) <= skb->data
24	    /* If so, compare... */
25	    && ((memcmp(skb->mac.ethernet->h_source, info->srcaddr, ETH_ALEN)
26		== 0) ^ info->invert));
27}
28
29static int
30ipt_mac_checkentry(const char *tablename,
31		   const struct ipt_ip *ip,
32		   void *matchinfo,
33		   unsigned int matchsize,
34		   unsigned int hook_mask)
35{
36	/* FORWARD isn't always valid, but it's nice to be able to do --RR */
37	if (hook_mask
38	    & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_IN)
39		| (1 << NF_IP_FORWARD))) {
40		printk("ipt_mac: only valid for PRE_ROUTING, LOCAL_IN or FORWARD.\n");
41		return 0;
42	}
43
44	if (matchsize != IPT_ALIGN(sizeof(struct ipt_mac_info)))
45		return 0;
46
47	return 1;
48}
49
50static struct ipt_match mac_match
51= { { NULL, NULL }, "mac", &match, &ipt_mac_checkentry, NULL, THIS_MODULE };
52
53static int __init init(void)
54{
55	return ipt_register_match(&mac_match);
56}
57
58static void __exit fini(void)
59{
60	ipt_unregister_match(&mac_match);
61}
62
63module_init(init);
64module_exit(fini);
65MODULE_LICENSE("GPL");
66