netfilter: nft_flow_offload: Unmask upper DSCP bits in nft_flow_route()

Unmask the upper DSCP bits when calling nf_route() which eventually
calls 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/netfilter/nft_flow_offload.c

@@ -9,6 +9,7 @@
 #include <linux/netfilter/nf_conntrack_common.h>
 #include <linux/netfilter/nf_tables.h>
 #include <net/ip.h> /* for ipv4 options. */
+#include <net/inet_dscp.h>
 #include <net/netfilter/nf_tables.h>
 #include <net/netfilter/nf_tables_core.h>
 #include <net/netfilter/nf_conntrack_core.h>
@@ -235,7 +236,7 @@ static int nft_flow_route(const struct nft_pktinfo *pkt,
 		fl.u.ip4.saddr = ct->tuplehash[!dir].tuple.src.u3.ip;
 		fl.u.ip4.flowi4_oif = nft_in(pkt)->ifindex;
 		fl.u.ip4.flowi4_iif = this_dst->dev->ifindex;
-		fl.u.ip4.flowi4_tos = RT_TOS(ip_hdr(pkt->skb)->tos);
+		fl.u.ip4.flowi4_tos = ip_hdr(pkt->skb)->tos & INET_DSCP_MASK;
 		fl.u.ip4.flowi4_mark = pkt->skb->mark;
 		fl.u.ip4.flowi4_flags = FLOWI_FLAG_ANYSRC;
 		break;