Shahar Liberman enhanced the reliability and security of overlay-based storage layers in the containers/storage and containers/container-libs repositories by addressing critical permission-check issues. He improved the Exists() and Lexists() functions to use the AT_EACCESS flag with the faccessat system call, ensuring that existence checks accurately reflect effective user permissions, even when users possess capabilities but lack direct file permissions. Working in Go and leveraging deep knowledge of Linux internals and system programming, Shahar’s targeted bug fixes reduced permission-denied errors during layer creation and access, aligning permission semantics across repositories and contributing to more predictable, maintainable storage operations in multi-user environments.