net: fib_rules: Add port mask attributes

Add attributes that allow matching on source and destination ports with
a mask. Matching on the source port with a mask is needed in deployments
where users encode path information into certain bits of the UDP source
port.

Temporarily set the type of the attributes to 'NLA_REJECT' while support
is being added.

Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20250217134109.311176-2-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/uapi/linux/fib_rules.h

@@ -70,6 +70,8 @@ enum {
 	FRA_DSCP,	/* dscp */
 	FRA_FLOWLABEL,	/* flowlabel */
 	FRA_FLOWLABEL_MASK,	/* flowlabel mask */
+	FRA_SPORT_MASK,	/* sport mask */
+	FRA_DPORT_MASK,	/* dport mask */
 	__FRA_MAX
 };