Language Abstractions for Hardware-based Control-Flow Integrity Monitoring

Control-Flow Integrity (CFI) is a software protection mechanism that detects a class of code reuse attacks by identifying anomalous control-flows within an executing program. Hardware-based CFI has the promise of the security benefits of CFI without the performance overhead and complexity of software-based CFI: generally speaking, hardware-based monitors are more difficult to bypass, offer lower performance overheads than software-based monitors, and, furthermore, hardware-based CFI can be performed without the necessity of altering application binaries or instrumenting language compilers. Although hardware-based CFI is an active area of research and there is a growing literature describing CFI strategies at a high-level, there is, to the authors' best knowledge, no work on languages specially tailored to the specification and implementation of CFI monitors. This article presents a proof-of-concept domain-specific language with built-in abstractions for expressing control-flow constraints along with a compiler that targets the functional hardware description language ReWire. While the case study is small, it indicates, we argue, an approach to rapid-prototyping hardware-based monitors enforcing CFI that is quick, flexible, and extensible as well as being amenable to formal verification.