[IPv6] route: Fix prohibit and blackhole routing decision

Lookups resolving to ip6_blk_hole_entry must result in silently
discarding the packets whereas an ip6_pkt_prohibit_entry is
supposed to cause an ICMPV6_ADM_PROHIBITED message to be sent.

Thanks to Kim Nordlund <kim.nordlund@nokia.com> for noticing
this bug.
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -94,6 +94,9 @@ static int		 ip6_dst_gc(void);
 
 static int		ip6_pkt_discard(struct sk_buff *skb);
 static int		ip6_pkt_discard_out(struct sk_buff *skb);
+static int		ip6_pkt_prohibit(struct sk_buff *skb);
+static int		ip6_pkt_prohibit_out(struct sk_buff *skb);
+static int		ip6_pkt_blk_hole(struct sk_buff *skb);
 static void		ip6_link_failure(struct sk_buff *skb);
 static void		ip6_rt_update_pmtu(struct dst_entry *dst, u32 mtu);
 
@@ -150,8 +153,8 @@ struct rt6_info ip6_prohibit_entry = {
 			.obsolete	= -1,
 			.error		= -EACCES,
 			.metrics	= { [RTAX_HOPLIMIT - 1] = 255, },
-			.input		= ip6_pkt_discard,
-			.output		= ip6_pkt_discard_out,
+			.input		= ip6_pkt_prohibit,
+			.output		= ip6_pkt_prohibit_out,
 			.ops		= &ip6_dst_ops,
 			.path		= (struct dst_entry*)&ip6_prohibit_entry,
 		}
@@ -170,8 +173,8 @@ struct rt6_info ip6_blk_hole_entry = {
 			.obsolete	= -1,
 			.error		= -EINVAL,
 			.metrics	= { [RTAX_HOPLIMIT - 1] = 255, },
-			.input		= ip6_pkt_discard,
-			.output		= ip6_pkt_discard_out,
+			.input		= ip6_pkt_blk_hole,
+			.output		= ip6_pkt_blk_hole,
 			.ops		= &ip6_dst_ops,
 			.path		= (struct dst_entry*)&ip6_blk_hole_entry,
 		}
@@ -1742,24 +1745,46 @@ int ipv6_route_ioctl(unsigned int cmd, void __user *arg)
  *	Drop the packet on the floor
  */
 
-static int ip6_pkt_discard(struct sk_buff *skb)
+static inline int ip6_pkt_drop(struct sk_buff *skb, int code)
 {
 	int type = ipv6_addr_type(&skb->nh.ipv6h->daddr);
 	if (type == IPV6_ADDR_ANY || type == IPV6_ADDR_RESERVED)
 		IP6_INC_STATS(IPSTATS_MIB_INADDRERRORS);
 
 	IP6_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
-	icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_NOROUTE, 0, skb->dev);
+	icmpv6_send(skb, ICMPV6_DEST_UNREACH, code, 0, skb->dev);
 	kfree_skb(skb);
 	return 0;
 }
 
+static int ip6_pkt_discard(struct sk_buff *skb)
+{
+	return ip6_pkt_drop(skb, ICMPV6_NOROUTE);
+}
+
 static int ip6_pkt_discard_out(struct sk_buff *skb)
 {
 	skb->dev = skb->dst->dev;
 	return ip6_pkt_discard(skb);
 }
 
+static int ip6_pkt_prohibit(struct sk_buff *skb)
+{
+	return ip6_pkt_drop(skb, ICMPV6_ADM_PROHIBITED);
+}
+
+static int ip6_pkt_prohibit_out(struct sk_buff *skb)
+{
+	skb->dev = skb->dst->dev;
+	return ip6_pkt_prohibit(skb);
+}
+
+static int ip6_pkt_blk_hole(struct sk_buff *skb)
+{
+	kfree_skb(skb);
+	return 0;
+}
+
 /*
  *	Allocate a dst for local (unicast / anycast) address.
  */