The uses of role hierarchies in access control

Abstract

The value of role-based access control (RBAC) is now well recognised. One aspect of it is the ability to make access decisions based upon the position of a role in a hierarchy. It is now recognised that there are some problems associated with this, because of the risk that these decisions may conflict with the control principles that are applied within an organisation. The aim of this paper is to identify the possible uses of role hierarchies in simplifying access rules, while remaining within the constraints of organisational control principles. We use the concept of authority state, i.e., the set of fixed and variable policies and rules in the system which influence the Reference Monitor's access decisions. We then consider the uses of role hierarchies in two separate contexts: first, within a static view of the authority state, where role hierarchies may be used by an access control decision facility; and second, as constraints upon permissible changes to the authority state. We conclude that role hierarchies have some possible uses within the static view, but that they are more important as a means of constraining the permissible changes to the authority state. We make proposals for further research on the place of role hierarchies in controlling change.