summaryrefslogtreecommitdiff
path: root/net/bridge/netfilter/ebt_arp.c
diff options
context:
space:
mode:
Diffstat (limited to 'net/bridge/netfilter/ebt_arp.c')
-rw-r--r--net/bridge/netfilter/ebt_arp.c140
1 files changed, 140 insertions, 0 deletions
diff --git a/net/bridge/netfilter/ebt_arp.c b/net/bridge/netfilter/ebt_arp.c
new file mode 100644
index 00000000000..b94c48cb6e4
--- /dev/null
+++ b/net/bridge/netfilter/ebt_arp.c
@@ -0,0 +1,140 @@
+/*
+ * ebt_arp
+ *
+ * Authors:
+ * Bart De Schuymer <bdschuym@pandora.be>
+ * Tim Gardner <timg@tpi.com>
+ *
+ * April, 2002
+ *
+ */
+
+#include <linux/netfilter_bridge/ebtables.h>
+#include <linux/netfilter_bridge/ebt_arp.h>
+#include <linux/if_arp.h>
+#include <linux/if_ether.h>
+#include <linux/module.h>
+
+static int ebt_filter_arp(const struct sk_buff *skb, const struct net_device *in,
+ const struct net_device *out, const void *data, unsigned int datalen)
+{
+ struct ebt_arp_info *info = (struct ebt_arp_info *)data;
+ struct arphdr _arph, *ah;
+
+ ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
+ if (ah == NULL)
+ return EBT_NOMATCH;
+ if (info->bitmask & EBT_ARP_OPCODE && FWINV(info->opcode !=
+ ah->ar_op, EBT_ARP_OPCODE))
+ return EBT_NOMATCH;
+ if (info->bitmask & EBT_ARP_HTYPE && FWINV(info->htype !=
+ ah->ar_hrd, EBT_ARP_HTYPE))
+ return EBT_NOMATCH;
+ if (info->bitmask & EBT_ARP_PTYPE && FWINV(info->ptype !=
+ ah->ar_pro, EBT_ARP_PTYPE))
+ return EBT_NOMATCH;
+
+ if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP)) {
+ uint32_t _addr, *ap;
+
+ /* IPv4 addresses are always 4 bytes */
+ if (ah->ar_pln != sizeof(uint32_t))
+ return EBT_NOMATCH;
+ if (info->bitmask & EBT_ARP_SRC_IP) {
+ ap = skb_header_pointer(skb, sizeof(struct arphdr) +
+ ah->ar_hln, sizeof(_addr),
+ &_addr);
+ if (ap == NULL)
+ return EBT_NOMATCH;
+ if (FWINV(info->saddr != (*ap & info->smsk),
+ EBT_ARP_SRC_IP))
+ return EBT_NOMATCH;
+ }
+
+ if (info->bitmask & EBT_ARP_DST_IP) {
+ ap = skb_header_pointer(skb, sizeof(struct arphdr) +
+ 2*ah->ar_hln+sizeof(uint32_t),
+ sizeof(_addr), &_addr);
+ if (ap == NULL)
+ return EBT_NOMATCH;
+ if (FWINV(info->daddr != (*ap & info->dmsk),
+ EBT_ARP_DST_IP))
+ return EBT_NOMATCH;
+ }
+ }
+
+ if (info->bitmask & (EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC)) {
+ unsigned char _mac[ETH_ALEN], *mp;
+ uint8_t verdict, i;
+
+ /* MAC addresses are 6 bytes */
+ if (ah->ar_hln != ETH_ALEN)
+ return EBT_NOMATCH;
+ if (info->bitmask & EBT_ARP_SRC_MAC) {
+ mp = skb_header_pointer(skb, sizeof(struct arphdr),
+ sizeof(_mac), &_mac);
+ if (mp == NULL)
+ return EBT_NOMATCH;
+ verdict = 0;
+ for (i = 0; i < 6; i++)
+ verdict |= (mp[i] ^ info->smaddr[i]) &
+ info->smmsk[i];
+ if (FWINV(verdict != 0, EBT_ARP_SRC_MAC))
+ return EBT_NOMATCH;
+ }
+
+ if (info->bitmask & EBT_ARP_DST_MAC) {
+ mp = skb_header_pointer(skb, sizeof(struct arphdr) +
+ ah->ar_hln + ah->ar_pln,
+ sizeof(_mac), &_mac);
+ if (mp == NULL)
+ return EBT_NOMATCH;
+ verdict = 0;
+ for (i = 0; i < 6; i++)
+ verdict |= (mp[i] ^ info->dmaddr[i]) &
+ info->dmmsk[i];
+ if (FWINV(verdict != 0, EBT_ARP_DST_MAC))
+ return EBT_NOMATCH;
+ }
+ }
+
+ return EBT_MATCH;
+}
+
+static int ebt_arp_check(const char *tablename, unsigned int hookmask,
+ const struct ebt_entry *e, void *data, unsigned int datalen)
+{
+ struct ebt_arp_info *info = (struct ebt_arp_info *)data;
+
+ if (datalen != EBT_ALIGN(sizeof(struct ebt_arp_info)))
+ return -EINVAL;
+ if ((e->ethproto != htons(ETH_P_ARP) &&
+ e->ethproto != htons(ETH_P_RARP)) ||
+ e->invflags & EBT_IPROTO)
+ return -EINVAL;
+ if (info->bitmask & ~EBT_ARP_MASK || info->invflags & ~EBT_ARP_MASK)
+ return -EINVAL;
+ return 0;
+}
+
+static struct ebt_match filter_arp =
+{
+ .name = EBT_ARP_MATCH,
+ .match = ebt_filter_arp,
+ .check = ebt_arp_check,
+ .me = THIS_MODULE,
+};
+
+static int __init init(void)
+{
+ return ebt_register_match(&filter_arp);
+}
+
+static void __exit fini(void)
+{
+ ebt_unregister_match(&filter_arp);
+}
+
+module_init(init);
+module_exit(fini);
+MODULE_LICENSE("GPL");