xfrm: Convert struct xfrm_dst_lookup_params -> tos to dscp_t.

Add type annotation to the "tos" field of struct xfrm_dst_lookup_params,
to ensure that the ECN bits aren't mistakenly taken into account when
doing route lookups. Rename that field (tos -> dscp) to make that
change explicit.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

Author: Guillaume Nault

include/net/xfrm.h

@@ -19,6 +19,7 @@
 
 #include <net/sock.h>
 #include <net/dst.h>
+#include <net/inet_dscp.h>
 #include <net/ip.h>
 #include <net/route.h>
 #include <net/ipv6.h>
@@ -354,7 +355,7 @@ void xfrm_if_unregister_cb(void);
 
 struct xfrm_dst_lookup_params {
 	struct net *net;
-	int tos;
+	dscp_t dscp;
 	int oif;
 	xfrm_address_t *saddr;
 	xfrm_address_t *daddr;

net/ipv4/xfrm4_policy.c

@@ -14,6 +14,7 @@
 #include <linux/inetdevice.h>
 #include <net/dst.h>
 #include <net/xfrm.h>
+#include <net/inet_dscp.h>
 #include <net/ip.h>
 #include <net/l3mdev.h>
 
@@ -24,7 +25,7 @@ static struct dst_entry *__xfrm4_dst_lookup(struct flowi4 *fl4,
 
 	memset(fl4, 0, sizeof(*fl4));
 	fl4->daddr = params->daddr->a4;
-	fl4->flowi4_tos = params->tos;
+	fl4->flowi4_tos = inet_dscp_to_dsfield(params->dscp);
 	fl4->flowi4_l3mdev = l3mdev_master_ifindex_by_index(params->net,
 							    params->oif);
 	fl4->flowi4_mark = params->mark;

net/xfrm/xfrm_policy.c

@@ -312,7 +312,7 @@ static inline struct dst_entry *xfrm_dst_lookup(struct xfrm_state *x,
 	params.net = net;
 	params.saddr = saddr;
 	params.daddr = daddr;
-	params.tos = inet_dscp_to_dsfield(dscp);
+	params.dscp = dscp;
 	params.oif = oif;
 	params.mark = mark;
 	params.ipproto = x->id.proto;