Section: Research Program

Efficient Formally Secure Compilers to a Tagged Architecture

Severe low-level vulnerabilities abound in today’s computer systems, allowing cyber-attackers to remotely gain full control. This happens in big part because our programming languages, compilers, and architectures were designed in an era of scarce hardware resources and too often trade off security for efficiency. The semantics of mainstream low-level languages like C is inherently insecure, and even for safer languages, establishing security with respect to a high-level semantics does not guarantee the absence of low-level attacks. Secure compilation using the coarse-grained protection mechanisms provided by mainstream hardware architectures would be too inefficient for most practical scenarios.

We aim to leverage emerging hardware capabilities for fine-grained protection to build the first, efficient secure compilation chains for realistic low-level programming languages (the C language, and Low* a safe subset of C embedded in F* for verification [71]). These compilation chains will provide a secure semantics for all programs and will ensure that high-level abstractions cannot be violated even when interacting with untrusted low-level code. To achieve this level of security without sacrificing efficiency, our secure compilation chains target a tagged architecture [50], which associates a metadata tag to each word and efficiently propagates and checks tags according to software-defined rules. We hope to experimentally evaluate and carefully optimize the efficiency of our secure compilation chains on realistic workloads and standard benchmark suites. We are also using property-based testing and formal verification to provide high confidence that our compilation chains are indeed secure. Formally, we are constructing machine-checked proofs of a new security criterion we call robustly safe compilation, which is defined as the preservation of safety properties even against an adversarial context [46], [47]. This strong criterion complements compiler correctness and ensures that no machine-code attacker can do more harm to securely compiled components than a component already could with respect to a secure source-level semantics.