This is done by use of the "Access by Company" provisions in the Access settings. This is done on the CM side (right click project, select "Project Access") and then you must modify within each user.
This can't be set in the Administration module for either user or Template.
A couple notes/cautions:
1. This is not enforced in every log--see the help documentation on the Project Access screen.
2. I'm not sure if the "Distribution" section enables access or not--typically it's just the To and From
3. This is set by USER and PROJECT--so if you have many users/many projects it will represent some work to get set.
The Access by Company feature varies with version of Contract Management.
For full details, see Note 1277125.1 - Access by Company - Access Details by Document Type
The Access by Company feature is expanded in Contract Management 14.
Beginning in Contract Management 14, 'Access by Company' is not enforced for only the following two modules:
-- Cost Worksheets