TimeDice: Schedulability-Preserving Priority Inversion for Mitigating Covert Timing Channels Between Real-time Partitions
TimeDice: Schedulability-Preserving Priority Inversion for Mitigating Covert Timing Channels Between Real-time Partitions
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DOI：
10.1109/dsn53405.2022.00052
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发表时间：
2022-06
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影响因子：
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通讯作者：
Man-Ki Yoon;Jung-Eun Kim;Richard M. Bradford;Zhong Shao
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文献类型：
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作者：
Man-Ki Yoon;Jung-Eun Kim;Richard M. Bradford;Zhong Shao
定时可预测性是在隐蔽定时信道上成功通信的前提条件。实时系统特别容易受到定时通道的影响，因为由于调度中的有限不确定性，实时应用很容易具有时间局部性。在本文中，我们证明了即使在严格实施时间分区之间的时间隔离的情况下，实时应用程序也可以产生隐藏的信息流。然后，我们介绍了一种在线算法，该算法将时间分区调度随机化，以减少时间分区的时间局部性，同时保证时间分区的可调度性，从而保证时间分区之间的时间隔离。我们还分析了随机化对实时任务响应性的影响。通过在一个基于Linux的实时操作系统上的实现，验证了分析和评估了调度开销以及对一个实验实时系统的影响。
Timing predictability is a precondition for successful communication over a covert timing channel. Real-time systems are particularly vulnerable to timing channels because real-time applications can easily have temporal locality due to limited uncertainty in schedules. In this paper, we show that real-time applications can create hidden information flow even when the temporal isolation among the time partitions is strictly enforced. We then introduce an online algorithm that randomizes time-partition schedules to reduce the temporal locality, while guaranteeing the schedulability of, and thus the temporal isolation among, time partitions. We also present an analysis of the cost of the randomization on the responsiveness of real-time tasks. From an implementation on a Linux-based real-time operating system, we validate the analysis and evaluate the scheduling overhead as well as the impact on an experimental real-time system.