Commit 6d55cb91 authored Mar 03, 2010 by Timo Teräs Committed by David S. Miller Mar 04, 2010

gre: fix hard header destination address checking

ipgre_header() can be called with zero daddr when the gre device is
configured as multipoint tunnel and still has the NOARP flag set (which is
typically cleared by the userspace arp daemon). If the NOARP packets are
not dropped, ipgre_tunnel_xmit() will take rt->rt_gateway (= NBMA IP) and
use that for route look up (and may lead to bogus xfrm acquires).

The multicast address check is removed as sending to multicast group should
be ok. In fact, if gre device has a multicast address as destination
ipgre_header is always called with multicast address.

Signed-off-by: Timo Teras <timo.teras@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent c839d30a

net/ipv4/ip_gre.c

+2 −5

Original line number	Diff line number	Diff line
		@@ -1144,12 +1144,9 @@ static int ipgre_header(struct sk_buff skb, struct net_device dev,

		if (saddr)
		memcpy(&iph->saddr, saddr, 4);

		if (daddr) {
		if (daddr)
		memcpy(&iph->daddr, daddr, 4);
		return t->hlen;
		}
		if (iph->daddr && !ipv4_is_multicast(iph->daddr))
		if (iph->daddr)
		return t->hlen;

		return -t->hlen;

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