[PATCH 075/102] ipv6: don't accept multicast traffic with scope 0

[Luis Henriques]

3.5.7.10 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hannes Frederic Sowa <hannes at stressinduktion.org>

commit 20314092c1b41894d8c181bf9aa6f022be2416aa upstream.

v2:
a) moved before multicast source address check
b) changed comment to netdev style

Cc: Erik Hugne <erik.hugne at ericsson.com>
Cc: YOSHIFUJI Hideaki <yoshfuji at linux-ipv6.org>
Acked-by: YOSHIFUJI Hideaki <yoshfuji at linux-ipv6.org>
Signed-off-by: Hannes Frederic Sowa <hannes at stressinduktion.org>
Acked-by: YOSHIFUJI Hideaki <yoshfuji at linux-ipv6.org>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/ipv6/ip6_input.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 61dfb1d..311eac7 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -111,6 +111,15 @@ int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt
 	    ipv6_addr_loopback(&hdr->daddr))
 		goto err;
 
+	/* RFC4291 2.7
+	 * Nodes must not originate a packet to a multicast address whose scope
+	 * field contains the reserved value 0; if such a packet is received, it
+	 * must be silently dropped.
+	 */
+	if (ipv6_addr_is_multicast(&hdr->daddr) &&
+	    IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
+		goto err;
+
 	/*
 	 * RFC4291 2.7
 	 * Multicast addresses must not be used as source addresses in IPv6
-- 
1.8.1.2