Avoiding timing channels in fixed-priority schedulers

A practically feasible modification to fixed-priority schedulers allows to avoid timing channels despite threads having access to precise clocks. This modification is rather simple: we compute at admission time a static predicate that states whether a thread may possibly leak information; if such a thread blocks we switch to the idle thread instead. We describe the modified scheduler, provide a mechanical PVS-based proof of noninterference and show how common admission algorithms can be reused to give real-time guarantees for this modified scheduler. While providing similar isolation guarantees, our approach outperforms timepartitioning schedulers in terms of achieved real-time guarantees. Categories and Subject Descriptors D.4.6 [Software]: Operating SystemsSecurity and Protection[Information flow controls]; D.4.1 [Software]: Operating SystemsProcess Management[Scheduling] General Terms Security, Verification Keywords real-time, fixed-priority scheduling, security, information flow, ...

• Type: Conference
• Year: 2008
• Where: CCS
• Authors: Marcus Völp, Claude-Joachim Hamann, Hermann Härtig
• Keywords: Achieved Real-time Guarantees, CCS 2008, Modified Scheduler, Real-time Guarantees, Security Privacy