+/* ISATAP (RFC4214) - check source address */
+static int
+isatap_srcok(struct sk_buff *skb, struct iphdr *iph, struct net_device *dev)
+{
+ struct neighbour *neigh;
+ struct dst_entry *dst;
+ struct rt6_info *rt;
+ struct flowi fl;
+ struct in6_addr *addr6;
+ struct in6_addr rtr;
+ struct ipv6hdr *iph6;
+ int ok = 0;
+
+ /* from onlink default router */
+ ipv6_addr_set(&rtr, htonl(0xFE800000), 0, 0, 0);
+ ipv6_isatap_eui64(rtr.s6_addr + 8, iph->saddr);
+ if ((rt = rt6_get_dflt_router(&rtr, dev))) {
+ dst_release(&rt->u.dst);
+ return 1;
+ }
+
+ iph6 = ipv6_hdr(skb);
+ memset(&fl, 0, sizeof(fl));
+ fl.proto = iph6->nexthdr;
+ ipv6_addr_copy(&fl.fl6_dst, &iph6->saddr);
+ fl.oif = dev->ifindex;
+ security_skb_classify_flow(skb, &fl);
+
+ dst = ip6_route_output(NULL, &fl);
+ if (!dst->error && (dst->dev == dev) && (neigh = dst->neighbour)) {
+
+ addr6 = (struct in6_addr*)&neigh->primary_key;
+
+ /* from correct previous hop */
+ if (ipv6_addr_is_isatap(addr6) &&
+ (addr6->s6_addr32[3] == iph->saddr))
+ ok = 1;
+ }
+ dst_release(dst);
+ return ok;
+}
+