ipv4: ip_tunnel: Unmask upper DSCP bits in ip_tunnel_bind_dev()

[ Upstream commit e7191e51 ]

Unmask the upper DSCP bits when initializing an IPv4 flow key via
ip_tunnel_init_flow() before passing it to ip_route_output_key() so that
in the future we could perform the FIB lookup according to the full DSCP
value.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: b5a7b661 ("net: Fix netns for ip_tunnel_init_flow()")
Signed-off-by: Sasha Levin <sashal@kernel.org>

net/ipv4/ip_tunnel.c

@@ -293,7 +293,7 @@ static int ip_tunnel_bind_dev(struct net_device *dev)
 
 		ip_tunnel_init_flow(&fl4, iph->protocol, iph->daddr,
 				    iph->saddr, tunnel->parms.o_key,
-				    RT_TOS(iph->tos), dev_net(dev),
+				    iph->tos & INET_DSCP_MASK, dev_net(dev),
 				    tunnel->parms.link, tunnel->fwmark, 0, 0);
 		rt = ip_route_output_key(tunnel->net, &fl4);