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：隔离化是一种防御性软件设计形式，其中应用程序被分解为相互隔离但可通信的组件。从工程投入和性能开销的角度来看，将隔离化改造引入现有应用程序通常被认为代价高昂。然而，近年来出现了一些隔离化方法，声称具有低工程投入和降低性能影响的特点。ARM Morello将现代ARM处理器与能力硬件增强RISC指令（CHERI）实现相结合，旨在提供高效且安全的隔离化。以往基于CHERI的隔离化研究仅限于仿真/FPGA原型。本文在Morello芯片上探索了使用CHERI的可能隔离化方案。我们提出了两种代表不同权衡（涉及工程投入、安全性、可扩展性和性能影响）的方法。我们在Morello芯片上运行裸机的原型操作系统上描述并实现了这些方法，对两个流行应用程序进行隔离化，并研究了性能开销。此外，我们表明，如果愿意在可扩展性和安全性上做出权衡，则可以用相当低的工程成本实现隔离化，且性能开销与其他地址空间内隔离机制相似。