[IB] Add checks to multicast attach and detach

Add checks so that we only allow multicast attach/detach with
a valid multicast GID and the correct QP type.
Signed-off-by: Jack Morgenstein <jackm@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/core/verbs.c

@@ -523,16 +523,22 @@ EXPORT_SYMBOL(ib_dealloc_fmr);
 
 int ib_attach_mcast(struct ib_qp *qp, union ib_gid *gid, u16 lid)
 {
-	return qp->device->attach_mcast ?
-		qp->device->attach_mcast(qp, gid, lid) :
-		-ENOSYS;
+	if (!qp->device->attach_mcast)
+		return -ENOSYS;
+	if (gid->raw[0] != 0xff || qp->qp_type != IB_QPT_UD)
+		return -EINVAL;
+
+	return qp->device->attach_mcast(qp, gid, lid);
 }
 EXPORT_SYMBOL(ib_attach_mcast);
 
 int ib_detach_mcast(struct ib_qp *qp, union ib_gid *gid, u16 lid)
 {
-	return qp->device->detach_mcast ?
-		qp->device->detach_mcast(qp, gid, lid) :
-		-ENOSYS;
+	if (!qp->device->detach_mcast)
+		return -ENOSYS;
+	if (gid->raw[0] != 0xff || qp->qp_type != IB_QPT_UD)
+		return -EINVAL;
+
+	return qp->device->detach_mcast(qp, gid, lid);
 }
 EXPORT_SYMBOL(ib_detach_mcast);