FlexOS: Easy Specialization of OS Safety Properties

Modern operating systems are tightly coupled to a specific isolation approach and safety mechanism. At design time, the isolation strategy is set in stone and rarely revisited later, due to prohibitive costs. This lack of flexibility hurts specialization, makes it hard to leverage new software/hardware isolation technologies, and makes the OS less resilient to attacks targeting the isolation mechanism. To address these issues we have developed FlexOS, a novel libOS approach that decouples isolation properties from the OS design. Depending on the configuration, the same FlexOS code can mimic a microkernel with multiple address-spaces, a single-address-space OS with Intel MPK compartments, or many other OS isolation approaches.

In this paper, we summarize the current state of FlexOS and present two main research avenues that we aim to explore next: automated porting to make OS safety property specialization really easy, and support for CHERI hardware capabilities to better showcase FlexOS’ potential.