flow: Extend flow informations with xfrm interface id.

Add a new flowi_xfrm structure with informations needed to do
a xfrm lookup. At the moment it keeps the informations about
the new xfrm interface id needed to lookup xfrm interfaces
that are introduced with a followup patch. We need this new
lookup key as other possible keys, like the ifindex is
already part of the xfrm selector and used as a key to
enforce the output device after the transformation in the
policy/state lookup.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Shannon Nelson <shannon.nelson@oracle.com>
Acked-by: Benedict Wong <benedictwong@google.com>
Tested-by: Benedict Wong <benedictwong@google.com>
Tested-by: Antony Antony <antony@phenome.org>
Reviewed-by: Eyal Birger <eyal.birger@gmail.com>

include/net/flow.h

@@ -26,6 +26,10 @@ struct flowi_tunnel {
 	__be64			tun_id;
 };
 
+struct flowi_xfrm {
+	__u32			if_id;
+};
+
 struct flowi_common {
 	int	flowic_oif;
 	int	flowic_iif;
@@ -39,6 +43,7 @@ struct flowi_common {
 #define FLOWI_FLAG_SKIP_NH_OIF		0x04
 	__u32	flowic_secid;
 	struct flowi_tunnel flowic_tun_key;
+	struct flowi_xfrm xfrm;
 	kuid_t  flowic_uid;
 };
 
@@ -78,6 +83,7 @@ struct flowi4 {
 #define flowi4_secid		__fl_common.flowic_secid
 #define flowi4_tun_key		__fl_common.flowic_tun_key
 #define flowi4_uid		__fl_common.flowic_uid
+#define flowi4_xfrm		__fl_common.xfrm
 
 	/* (saddr,daddr) must be grouped, same order as in IP header */
 	__be32			saddr;
@@ -109,6 +115,7 @@ static inline void flowi4_init_output(struct flowi4 *fl4, int oif,
 	fl4->flowi4_flags = flags;
 	fl4->flowi4_secid = 0;
 	fl4->flowi4_tun_key.tun_id = 0;
+	fl4->flowi4_xfrm.if_id = 0;
 	fl4->flowi4_uid = uid;
 	fl4->daddr = daddr;
 	fl4->saddr = saddr;
@@ -138,6 +145,7 @@ struct flowi6 {
 #define flowi6_secid		__fl_common.flowic_secid
 #define flowi6_tun_key		__fl_common.flowic_tun_key
 #define flowi6_uid		__fl_common.flowic_uid
+#define flowi6_xfrm		__fl_common.xfrm
 	struct in6_addr		daddr;
 	struct in6_addr		saddr;
 	/* Note: flowi6_tos is encoded in flowlabel, too. */
@@ -185,6 +193,7 @@ struct flowi {
 #define flowi_secid	u.__fl_common.flowic_secid
 #define flowi_tun_key	u.__fl_common.flowic_tun_key
 #define flowi_uid	u.__fl_common.flowic_uid
+#define flowi_xfrm	u.__fl_common.xfrm
 } __attribute__((__aligned__(BITS_PER_LONG/8)));
 
 static inline struct flowi *flowi4_to_flowi(struct flowi4 *fl4)