LLVM CFI Support for Rust

Abstract

We’re pleased to share that we’ve worked with the Rust community to add support for LLVM CFI and cross-language LLVM CFI (and LLVM KCFI and cross-language LLVM KCFI) to the Rust compiler as part of our work in the Rust Exploit Mitigations Project Group. This is the first implementation of cross-language, fine-grained, forward-edge control flow protection for mixed-language binaries that we know of. As the industry continues to explore Rust adoption, cross-language attacks in mixed-language binaries (also known as “mixed binaries”), and critically the absence of support for forward-edge control flow protection in the Rust compiler, are a major security concern when gradually migrating from C and C++ to Rust, and when C or C++ and Rust-compiled code share the same virtual address space.