Need to restrict some things to users

I have an ecommerce wordpress site that is close to completion. I have some functionality issues.

In a nutshell:

Sellers can register to sell items on the site. Once admin approves them, they can upload products. Now the problem is, once a seller registers and is approved, they have access to the entire media library of all the other sellers’ images. Is there a way to restrict them to only be able to see/use images uploaded by themselves?