netfilter: flowtable: Add FLOW_OFFLOAD_XMIT_UNSPEC xmit type

It could be xmit type was not set and would default to FLOW_OFFLOAD_XMIT_NEIGH
and in this type the gc expect to have a route info.
Fix that by adding FLOW_OFFLOAD_XMIT_UNSPEC which defaults to 0.

Fixes: 8b9229d1 ("netfilter: flowtable: dst_check() from garbage collector path")
Signed-off-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_flow_table.h

@@ -92,7 +92,8 @@ enum flow_offload_tuple_dir {
 #define FLOW_OFFLOAD_DIR_MAX	IP_CT_DIR_MAX
 
 enum flow_offload_xmit_type {
-	FLOW_OFFLOAD_XMIT_NEIGH		= 0,
+	FLOW_OFFLOAD_XMIT_UNSPEC	= 0,
+	FLOW_OFFLOAD_XMIT_NEIGH,
 	FLOW_OFFLOAD_XMIT_XFRM,
 	FLOW_OFFLOAD_XMIT_DIRECT,
 };

net/netfilter/nf_flow_table_core.c

@@ -130,6 +130,9 @@ static int flow_offload_fill_route(struct flow_offload *flow,
 		flow_tuple->dst_cache = dst;
 		flow_tuple->dst_cookie = flow_offload_dst_cookie(flow_tuple);
 		break;
+	default:
+		WARN_ON_ONCE(1);
+		break;
 	}
 	flow_tuple->xmit_type = route->tuple[dir].xmit_type;