Towards practical enforcement theories

Abstract

Runtime enforcement is a common mechanism for ensuring that program executions adhere to constraints specified by a security policy. It is based on two simple ideas: the enforcement mechanism should leave good executions without changes and make sure that the bad ones got amended. From the theory side, a number of papers [6,10,12] provide the precise characterization of good executions that can be captured by a security policy and thus enforced by a specific mechanism. Unfortunately, those theories do not distinguish what happens when an execution is actually bad (the practical case). The theory only says that the outcome of enforcement mechanism should be "good" but not how far should the bad execution be changed. If we consider a real-life example of a drug dispensation process in a hospital the notion of security automata or even edit automata would stop all requests by all doctors on all drugs and all dispensation protocols, as soon as a doctor forgot to insert the research protocol number. In this paper we explore a set of policies called iterative properties that revises the notion of good traces in terms of repeated iterations. We start discussing how an enforcement mechanism can actually deal with bad executions (and not just only the good ones). © Springer-Verlag 2009.