PKRU-safe: automatically locking down the heap between safe and unsafe languages

After more than twenty-five years of research, memory safety violations remain one of the major causes of security vulnerabilities in real-world software. Memory-safe languages, like Rust, have demonstrated that compiler technology can assist developers in writing efficient low-level code without the risk of memory corruption. However, many memory-safe languages still have to interface with unsafe code to some extent, which opens up the possibility for attackers to exploit memory-corruption vulnerabilities in the unsafe part of the system and subvert the safety guarantees provided by the memory-safe language.

In this paper, we present PKRU-Safe, an automated method for enforcing the principle of least privilege on unsafe components in mixed-language environments. PKRU-Safe ensures that unsafe (external) code cannot corrupt or otherwise abuse memory used exclusively by the safe-language components. Our approach is automated using traditional compiler infrastructure to limit memory accesses for developer-designated components efficiently. PKRU-Safe does not require any modifications to the program's original data flows or execution model. It can be adopted by projects containing legacy code with minimal