From 1c4a154e5253687c51123956dfcee9e9dfa8542d Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Tue, 26 Mar 2013 08:13:34 +0000 Subject: [PATCH] ipv6: don't accept node local multicast traffic from the wire Erik Hugne's errata proposal (Errata ID: 3480) to RFC4291 has been verified: http://www.rfc-editor.org/errata_search.php?eid=3480 We have to check for pkt_type and loopback flag because either the packets are allowed to travel over the loopback interface (in which case pkt_type is PACKET_HOST and IFF_LOOPBACK flag is set) or they travel over a non-loopback interface back to us (in which case PACKET_TYPE is PACKET_LOOPBACK and IFF_LOOPBACK flag is not set). Cc: Erik Hugne Cc: YOSHIFUJI Hideaki Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/ipv6/ip6_input.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c index e33fe0ab2568..2bab2aa59745 100644 --- a/net/ipv6/ip6_input.c +++ b/net/ipv6/ip6_input.c @@ -118,6 +118,18 @@ int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt ipv6_addr_loopback(&hdr->daddr)) goto err; + /* RFC4291 Errata ID: 3480 + * Interface-Local scope spans only a single interface on a + * node and is useful only for loopback transmission of + * multicast. Packets with interface-local scope received + * from another node must be discarded. + */ + if (!(skb->pkt_type == PACKET_LOOPBACK || + dev->flags & IFF_LOOPBACK) && + ipv6_addr_is_multicast(&hdr->daddr) && + IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1) + 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 -- 2.39.5