Information Leakage as a Scheduling Resource

Abstract : High-security processes have to load confidential information into shared resources as part of their operation. This confidential information may be leaked (directly or indirectly) to low-security processes via the shared resource. This paper considers leakage from high-security to low-security processes from the perspective of scheduling. The workflow model is here extended to support preemption, security levels, and leakage. Formalization of leakage properties is then built upon this extended model, allowing formal reasoning about the security of schedulers. Several heuristics are presented in the form of compositional preprocessors and postprocessors as part of a more general scheduling approach. The effectiveness of such heuristics are evaluated experimentally, showing them to achieve significantly better schedulability than the state of the art. Modeling of leakage from cache attacks is presented as a case study.