[IPV6]: Disallow RH0 by default.

A security issue is emerging.  Disallow Routing Header Type 0 by default
as we have been doing for IPv4.
Note: We allow RH2 by default because it is harmless.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 28e0c65..6ed6a8c 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -362,10 +362,27 @@
 	struct inet6_skb_parm *opt = IP6CB(skb);
 	struct in6_addr *addr = NULL;
 	struct in6_addr daddr;
+	struct inet6_dev *idev;
 	int n, i;
-
 	struct ipv6_rt_hdr *hdr;
 	struct rt0_hdr *rthdr;
+	int accept_source_route = ipv6_devconf.accept_source_route;
+
+	if (accept_source_route < 0 ||
+	    ((idev = in6_dev_get(skb->dev)) == NULL)) {
+		kfree_skb(skb);
+		return -1;
+	}
+	if (idev->cnf.accept_source_route < 0) {
+		in6_dev_put(idev);
+		kfree_skb(skb);
+		return -1;
+	}
+
+	if (accept_source_route > idev->cnf.accept_source_route)
+		accept_source_route = idev->cnf.accept_source_route;
+
+	in6_dev_put(idev);
 
 	if (!pskb_may_pull(skb, (skb->h.raw-skb->data)+8) ||
 	    !pskb_may_pull(skb, (skb->h.raw-skb->data)+((skb->h.raw[1]+1)<<3))) {
@@ -377,6 +394,22 @@
 
 	hdr = (struct ipv6_rt_hdr *) skb->h.raw;
 
+	switch (hdr->type) {
+#ifdef CONFIG_IPV6_MIP6
+		break;
+#endif
+	case IPV6_SRCRT_TYPE_0:
+		if (accept_source_route <= 0)
+			break;
+		kfree_skb(skb);
+		return -1;
+	default:
+		IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
+				 IPSTATS_MIB_INHDRERRORS);
+		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->type) - skb->nh.raw);
+		return -1;
+	}
+
 	if (ipv6_addr_is_multicast(&skb->nh.ipv6h->daddr) ||
 	    skb->pkt_type != PACKET_HOST) {
 		IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
@@ -434,11 +467,6 @@
 		}
 		break;
 #endif
-	default:
-		IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
-				 IPSTATS_MIB_INHDRERRORS);
-		icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->type) - skb->nh.raw);
-		return -1;
 	}
 
 	/*