论文标题
D-Box：嵌入式应用程序的DMA隔间化
D-Box: DMA-enabled Compartmentalization for Embedded Applications
论文作者
论文摘要
嵌入式和图像互联网（IoT）设备在许多域中的采用率都在增加。这些设备的安全性非常重要，因为它们通常用于控制关键的基础设施，医疗设备和车辆。隔离微控制器（MCU）资源以提高其安全性的现有解决方案面临着重大挑战，例如无法可用，内存保护单元（MPU）限制和显着缺乏直接内存访问（DMA）支持。然而，DMA对嵌入式应用程序的功率和性能要求至关重要。在本文中，我们提出了D-Box，这是一种系统的方法，可以使用实时操作系统（RTOS）启用嵌入式应用程序的隔室化解决方案的安全DMA操作。 D-box定义了参考体系结构和工作流程，以整体保护DMA操作。它提供了实用的方法来硬化内核并定义基于功能的安全策略，以简化具有强大安全性能的DMA操作。我们在流行的Freertos-MPU（F-MPU）上为Cortex-M3/M4实现了D-box原型。与标准F-MPU相比，D-box过程和更严格的安全模型启用了DMA操作，但它暴露了41倍的ROP（返回定向编程）小工具。 D-box仅增加了2％的处理器开销，同时将外围操作基准的功耗降低了18.2％。在可编程逻辑控制器（PLC）应用程序的实际案例研究中测试并确认了D-box的安全性和性能。
Embedded and Internet-of-Things (IoT) devices have seen an increase in adoption in many domains. The security of these devices is of great importance as they are often used to control critical infrastructure, medical devices, and vehicles. Existing solutions to isolate microcontroller (MCU) resources in order to increase their security face significant challenges such as specific hardware unavailability, Memory Protection Unit (MPU) limitations and a significant lack of Direct Memory Access (DMA) support. Nevertheless, DMA is fundamental for the power and performance requirements of embedded applications. In this paper, we present D-Box, a systematic approach to enable secure DMA operations for compartmentalization solutions of embedded applications using real-time operating systems (RTOS). D-Box defines a reference architecture and a workflow to protect DMA operations holistically. It provides practical methods to harden the kernel and define capability-based security policies for easy definition of DMA operations with strong security properties. We implemented a D-Box prototype for the Cortex-M3/M4 on top of the popular FreeRTOS-MPU (F-MPU). The D-Box procedures and a stricter security model enabled DMA operations, yet it exposed 41 times less ROP (return-orienting-programming) gadgets when compared with the standard F-MPU. D-Box adds only a 2% processor overhead while reducing the power consumption of peripheral operation benchmarks by 18.2%. The security properties and performance of D-Box were tested and confirmed on a real-world case study of a Programmable Logic Controller (PLC) application.
