ipv4: udp_tunnel: Unmask upper DSCP bits in udp_tunnel_dst_lookup()

Unmask the upper DSCP bits when calling ip_route_output_key() so that in
the future it could perform the FIB lookup according to the full DSCP
value.

Note that callers of udp_tunnel_dst_lookup() pass the entire DS field in
the 'tos' argument.
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/udp_tunnel_core.c

@@ -6,6 +6,7 @@
 #include <net/dst_metadata.h>
 #include <net/udp.h>
 #include <net/udp_tunnel.h>
+#include <net/inet_dscp.h>
 
 int udp_sock_create4(struct net *net, struct udp_port_cfg *cfg,
 		     struct socket **sockp)
@@ -232,7 +233,7 @@ struct rtable *udp_tunnel_dst_lookup(struct sk_buff *skb,
 	fl4.saddr = key->u.ipv4.src;
 	fl4.fl4_dport = dport;
 	fl4.fl4_sport = sport;
-	fl4.flowi4_tos = RT_TOS(tos);
+	fl4.flowi4_tos = tos & INET_DSCP_MASK;
 	fl4.flowi4_flags = key->flow_flags;
 
 	rt = ip_route_output_key(net, &fl4);