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System auditing is an essential tool for detecting malicious events and conducting forensic analysis. Although used extensively on general-purpose systems, auditing frameworks have not been designed with consideration for the unique constraints and properties of Real-Time Systems (RTS). System auditing could provide tremendous benefits for security-critical RTS. However, a naive deployment of auditing on RTS could violate the temporal requirements of the system while also rendering auditing incomplete and ineffectual. To ensure effective auditing that meets the computational needs of recording complete audit information while adhering to the temporal requirements of the RTS, it is essential to carefully integrate auditing into the real-time (RT) schedule. This work adapts the Linux Audit framework for use in RT Linux by leveraging the common properties of such systems, such as special purpose and predictability.Ellipsis, an efficient system for auditing RTS, is devised that learns the expected benign behaviors of the system and generates succinct descriptions of the expected activity. Evaluations using varied RT applications show thatEllipsisreduces the volume of audit records generated during benign activity by up to 97.55% while recording detailed logs for suspicious activities. Empirical analyses establish that the auditing infrastructure adheres to the properties of predictability and isolation that are important to RTS. Furthermore, the schedulability of RT tasksets under audit is comprehensively analyzed to enable the safe integration of auditing in RT task schedules. 

Information flow control is a canonical approach to access control in systems, allowing administrators to assure confidentiality and integrity through restricting the flow of data. Decentralized Information Flow Control (DIFC) harnesses application-layer semantics to allow more precise and accurate mediation of data. Unfortunately, past approaches to DIFC have depended on dedicated instrumentation efforts or developer buy-in. Thus, while DIFC has existed for decades, it has seen little-to-no adoption in commodity systems; the requirement for complete redesign or retrofitting of programs has proven too high a barrier. In this work, we make the surprising observation that developers have already unwittingly performed the instrumentation efforts required for DIFC — application event logging, a software development best practice used for telemetry and debugging, often contains the information needed to identify application-layer event processes that DIFC mediates. We present T-difc, a kernel-layer reference monitor framework that leverages the insights of application event logs to perform precise decentralized flow control. T-difc identifies and extracts these application events as they are created by monitoring application I/O to log files, then references an administrator-specified security policy to assign data labels and mediate the flow of data through the system. To our knowledge, T-difc is the first approach to DIFC that does not require developer support or custom instrumentation. In a survey of 15 popular open source applications, we demonstrate that T-difc works seamlessly on a variety of popular open source programs while imposing negligible runtime overhead on realistic policies and workloads. Thus, T-difc demonstrates a transparent and non-invasive path forward for the dissemination of decentralized information flow controls.