using Cancan to get company_a not to see company_b

I have created MVC for Product and there three companies that can enter data for their products. each companies have their own users who can enter product information. I want to use Cancan in a way that the company_a and company_b cannot see each other products listing nor can be able to delete or edit; however, I want company_c be able to see all product listing. Admin should be able to see all and edit/delete all.