Setting share/folder access based on computers

I have a situation with a share for which I am having no luck finding a solution. Here's what my users want for a certain share:

- A group of users should have read/write permissions to the share, no matter where they log in.

- All users should have read/write permissions to the share, but only if they're logged in from a certain group of computers.

Adding the computers to the NTFS permissions doesn't solve the problem.

The share is on a server running Windows Server 2008 R2, and it's on a domain with all the computers.

I can create GPOs if necessary.

Thanks!