We consider the problem of developing an abstract meta-model of access control in terms of which policies for protecting a principal's private information may be specified. Our concern is with developing the formal foundations of our conceptual model. For both the specific access control models and privacy policies, which may be defined in terms of the meta-model, we adopt a combining approach: we combine access control concepts to form the meta-model and we use a fibred logic for the formal foundations. Our approach enables data subjects to specify flexibly what access controls they wish to apply on their personal data and it provides a formal foundation for policies that are defined in terms of the meta-model.