net: fib_rules: Add flow label selector attributes

Add new FIB rule attributes which will allow user space to match on the
IPv6 flow label with a mask. Temporarily set the type of the attributes
to 'NLA_REJECT' while support is being added in the IPv6 code.

Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

include/uapi/linux/fib_rules.h

@@ -68,6 +68,8 @@ enum {
 	FRA_SPORT_RANGE, /* sport */
 	FRA_DPORT_RANGE, /* dport */
 	FRA_DSCP,	/* dscp */
+	FRA_FLOWLABEL,	/* flowlabel */
+	FRA_FLOWLABEL_MASK,	/* flowlabel mask */
 	__FRA_MAX
 };