Is the money I earn from designing my own logo, outside of office work, permissible for me or for the office?

If an employee designs a logo for the institution during working hours and using its tools, he is not permitted to take payment for it except with the permission of the one who owns that authority in the institution, because his benefit during that time is owned by the institution. However, if the design was done outside working hours and with his own tools, there is no harm in it, and the payment is his. And if it was done outside working hours but using the institution's tools, the payment for the design is his, but he must compensate the institution for the use of its tools, unless it permits him to do so.