5 * Bart De Schuymer <bdschuym@pandora.be>
6 * Tim Gardner <timg@tpi.com>
12 #include <linux/netfilter_bridge/ebtables.h>
13 #include <linux/netfilter_bridge/ebt_arp.h>
14 #include <linux/if_arp.h>
15 #include <linux/if_ether.h>
16 #include <linux/module.h>
18 static int ebt_filter_arp(const struct sk_buff *skb, const struct net_device *in,
19 const struct net_device *out, const void *data, unsigned int datalen)
21 struct ebt_arp_info *info = (struct ebt_arp_info *)data;
22 struct arphdr _arph, *ah;
24 ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
27 if (info->bitmask & EBT_ARP_OPCODE && FWINV(info->opcode !=
28 ah->ar_op, EBT_ARP_OPCODE))
30 if (info->bitmask & EBT_ARP_HTYPE && FWINV(info->htype !=
31 ah->ar_hrd, EBT_ARP_HTYPE))
33 if (info->bitmask & EBT_ARP_PTYPE && FWINV(info->ptype !=
34 ah->ar_pro, EBT_ARP_PTYPE))
37 if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP)) {
38 __be32 saddr, daddr, *sap, *dap;
40 if (ah->ar_pln != sizeof(__be32) || ah->ar_pro != htons(ETH_P_IP))
42 sap = skb_header_pointer(skb, sizeof(struct arphdr) +
43 ah->ar_hln, sizeof(saddr),
47 dap = skb_header_pointer(skb, sizeof(struct arphdr) +
48 2*ah->ar_hln+sizeof(saddr),
49 sizeof(daddr), &daddr);
52 if (info->bitmask & EBT_ARP_SRC_IP &&
53 FWINV(info->saddr != (*sap & info->smsk), EBT_ARP_SRC_IP))
55 if (info->bitmask & EBT_ARP_DST_IP &&
56 FWINV(info->daddr != (*dap & info->dmsk), EBT_ARP_DST_IP))
58 if (info->bitmask & EBT_ARP_GRAT &&
59 FWINV(*dap != *sap, EBT_ARP_GRAT))
63 if (info->bitmask & (EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC)) {
64 unsigned char _mac[ETH_ALEN], *mp;
67 if (ah->ar_hln != ETH_ALEN || ah->ar_hrd != htons(ARPHRD_ETHER))
69 if (info->bitmask & EBT_ARP_SRC_MAC) {
70 mp = skb_header_pointer(skb, sizeof(struct arphdr),
75 for (i = 0; i < 6; i++)
76 verdict |= (mp[i] ^ info->smaddr[i]) &
78 if (FWINV(verdict != 0, EBT_ARP_SRC_MAC))
82 if (info->bitmask & EBT_ARP_DST_MAC) {
83 mp = skb_header_pointer(skb, sizeof(struct arphdr) +
84 ah->ar_hln + ah->ar_pln,
89 for (i = 0; i < 6; i++)
90 verdict |= (mp[i] ^ info->dmaddr[i]) &
92 if (FWINV(verdict != 0, EBT_ARP_DST_MAC))
100 static int ebt_arp_check(const char *tablename, unsigned int hookmask,
101 const struct ebt_entry *e, void *data, unsigned int datalen)
103 struct ebt_arp_info *info = (struct ebt_arp_info *)data;
105 if (datalen != EBT_ALIGN(sizeof(struct ebt_arp_info)))
107 if ((e->ethproto != htons(ETH_P_ARP) &&
108 e->ethproto != htons(ETH_P_RARP)) ||
109 e->invflags & EBT_IPROTO)
111 if (info->bitmask & ~EBT_ARP_MASK || info->invflags & ~EBT_ARP_MASK)
116 static struct ebt_match filter_arp =
118 .name = EBT_ARP_MATCH,
119 .match = ebt_filter_arp,
120 .check = ebt_arp_check,
124 static int __init ebt_arp_init(void)
126 return ebt_register_match(&filter_arp);
129 static void __exit ebt_arp_fini(void)
131 ebt_unregister_match(&filter_arp);
134 module_init(ebt_arp_init);
135 module_exit(ebt_arp_fini);
136 MODULE_LICENSE("GPL");