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path: root/main/linux-grsec/0002-gre-fix-hard-header-destination-address-checking.patch
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From 9082391046940c410eac3bad065c8701998b5cab Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timo=20Ter=C3=A4s?= <timo.teras@iki.fi>
Date: Wed, 3 Mar 2010 04:01:13 +0000
Subject: [PATCH 02/18] 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>
(cherry picked from commit 6d55cb91a0020ac0d78edcad61efd6c8cf5785a3)
---
 net/ipv4/ip_gre.c |    7 ++-----
 1 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 1433338..ac88ce5 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1137,12 +1137,9 @@ 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;
-- 
1.7.0.2