Scaling Up Proactive Enforcement

Abstract Runtime enforcers receive events from a system and output commands ensuring the system’s policy compliance. Proactive enforcers extend traditional (reactive) enforcers by emitting commands at any time, rather only as a response to system actions. However, proactive enforcers have so far lacked support for many useful policy features. This, along with the existing tools’ poor performance, hinders their adoption. We present a performance-optimized, proactive enforcement algorithm for a rich policy language: metric first-order temporal logic with function applications, aggregations, and bindings. We have implemented this algorithm in EnfGuard , the first proactive enforcer tool that supports the above constructs. We evaluated our tool using a novel set of six benchmarks containing both real-world and synthetic policies and logs, demonstrating that it enforces realistic policies out-of-the-box and achieves the necessary performance to be used in real-time systems.