Would anyone know a way to restrict/allow by role the ability to add a rendering to a placeholder in the Experience Editor? This is for Sitecore 8.0.
If you want to restrict access to all renderings selected in the Allowed Controls field of a particular placeholder settings item, you can just restrict read access to the placeholder settings item.
If you are trying to be more selective, you may want to add your own processor for the
GetPlaceholderRenderings pipeline. You could use the rules engine to make it even more flexible similar to these projects:
If it is ok to not even display the rendering for that role, it can be sure done using Security Editor of Sitecore. We have done that and it works. But it is not an easy one to manage with conflicting roles and item rights inheritance. An experienced Sitecore Security can easily configure it though.
The logic is all renderings are Sitecore items and you can restrict access to any item by user/role permissions.