Compartmentalization is a form of defensive software design in which an application is broken down into isolated but communicating components. Retrofitting compartmentalization into existing applications is often thought to be expensive from the engineering effort and performance overhead points of view. Still, recent years have seen proposals of compartmentalization methods with promises of low engineering efforts and reduced performance impact. ARM Morello combines a modern ARM processor with an implementation of Capability Hardware Enhanced RISC Instructions (CHERI) aiming to provide efficient and secure compartmentalization. Past works exploring CHERI-based compartmentalization were restricted to emulated/FPGA prototypes. In this paper, we explore possible compartmentalization schemes with CHERI on the Morello chip. We propose two approaches representing different trade-offs in terms of engineering effort, security, scalability, and performance impact. We describe and implement these approaches on a prototype OS running bare metal on the Morello chip, compartmentalize two popular applications, and investigate the performance overheads. Furthermore, we show that compartmentalization can be achieved with an engineering cost that can be quite low if one is willing to trade off on scalability and security, and that performance overheads are similar to other intra-address space isolation mechanisms.

翻译：隔离是一种防御性软件设计形式，它将应用程序分解为相互隔离但可通信的组件。从工程工作量与性能开销的角度来看，将隔离机制改造到现有应用程序中通常被认为是昂贵的。尽管如此，近年仍出现了一些隔离方法提案，声称具有低工程工作量与较低性能影响。ARM Morello结合了现代ARM处理器与能力硬件增强RISC指令集（CHERI）的实现，旨在提供高效且安全的隔离。以往探索基于CHERI的隔离机制的工作受限于模拟/FPGA原型。本文在Morello芯片上探索了使用CHERI的可行隔离方案，提出了两种方法，在工程工作量、安全性、可扩展性与性能影响方面体现了不同的权衡取舍。我们在Morello芯片上裸机运行的原型操作系统中描述并实现了这些方法，对两个流行应用程序进行了隔离，并研究了性能开销。此外，我们表明，如果愿意在可扩展性与安全性上做出权衡，隔离机制可以以相当低的工程成本实现，且性能开销与其他地址空间内隔离机制相似。