ipv4: icmp: Unmask upper DSCP bits in icmp_reply()

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.
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/icmp.c

@@ -445,7 +445,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 	fl4.saddr = saddr;
 	fl4.flowi4_mark = mark;
 	fl4.flowi4_uid = sock_net_uid(net, NULL);
-	fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
+	fl4.flowi4_tos = ip_hdr(skb)->tos & INET_DSCP_MASK;
 	fl4.flowi4_proto = IPPROTO_ICMP;
 	fl4.flowi4_oif = l3mdev_master_ifindex(skb->dev);
 	security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));