bpf: Unmask upper DSCP bits in __bpf_redirect_neigh_v4()

Unmask the upper DSCP bits when calling ip_route_output_flow() so that
in the future it 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>

net/core/filter.c

@@ -2372,7 +2372,7 @@ static int __bpf_redirect_neigh_v4(struct sk_buff *skb, struct net_device *dev,
 		struct flowi4 fl4 = {
 			.flowi4_flags = FLOWI_FLAG_ANYSRC,
 			.flowi4_mark  = skb->mark,
-			.flowi4_tos   = RT_TOS(ip4h->tos),
+			.flowi4_tos   = ip4h->tos & INET_DSCP_MASK,
 			.flowi4_oif   = dev->ifindex,
 			.flowi4_proto = ip4h->protocol,
 			.daddr	      = ip4h->daddr,