TABLE OF CONTENTS Mandatory-access control (MAC) stands as a well-established model in computing security. Despite the fact that it lends itself well to military environments, it represents clearly distinguishing aspects in controlling information flow. Such information flow is foremost characterized as being deterministic. We begin with an introductory to the foundations of information flow. We describe the mathematical elements underpinning MAC as a latticebased information-flow model. Subsequently, we discuss the details of the Bell-LaPadula and the Biba models. The first one is based on the need to preserve confidentiality of information flow, while the second is concerned with maintaining integrity. We compare the two models and describe scenarios in which they can be combined. Finally, we introduce the Chinese-wall policy as an instance of the lattice-based information-flow policy applicable in commercial environments.
In a system governed by the mandatory-access-control model, user privileges are not resource-owner centric. In fact, no concept of ownership does exist in MAC, which is rather based on a policy that is driven by the sensitivity of the protected information. To access a MAC-protected object, one must hold the proper security clearance required by that object. The security label of a resource is matched up against the clearance of an attempting accessor. MAC policies fall under what is known as lattice-based access-control system. Information flow in these systems is formally determined by the mathematical structure of the underlying lattice that reflects it. We begin by reviewing the foundations behind the MAC model.
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