FC-TEE: Lightweight Trusted Execution Environment for Low-Cost UAV Flight Control Systems

Unmanned Aerial Vehicle (UAV) flight control systems are increasingly exposed to software-level security threats. However, existing Trusted Execution Environment (TEE) technologies that can effectively defend against software attacks are difficult to deploy on the low-cost UAVs due to: (1) the lack of onboard security hardware, (2) limited Memory Protection Unit (MPU) resources, and (3) strict real-time requirements. To address these issues, we design FC-TEE, a lightweight TEE framework tailored for low-cost UAV platforms, which integrates fine-grained memory isolation and a multi-level task scheduling strategy. By analyzing the flight control code and control principles, we provide three key attributes (task priority, maximum invocation frequency, and required argument types) of flight control tasks and classify these tasks into two categories (privileged tasks and common tasks) based on the attributes. Then, we run the privileged tasks in FC-TEE to achieve memory isolation from common tasks, protecting the privileged tasks from software attacks. Meanwhile, we design multi-level task scheduling based on the task priority and categories to ensure the real-time requirements of the flight control system. Compared with existing UAV protection solutions such as MINION and TrustZone-based RT-TEE, the average additional execution overhead introduced by FC-TEE only is 2.7%. We prototype FC-TEE on a real quadrotor platform and validate its effectiveness through task-level performance and security evaluations.