MicroTEE: Designing TEE OS Based on the Microkernel Architecture

Abstract

ARM TrustZone technology is widely used to provide Trusted Execution Environments (TEE) for mobile devices. However, most TEE OSes are implemented as monolithic kernels. In such designs, device drivers, kernel services and kernel modules all run in the kernel, which results in large size of the kernel. It is difficult to guarantee that all components of the kernel have no security vulnerabilities in the monolithic kernel architecture, such as the integer overflow vulnerability in Qualcomm QSEE TrustZone and the TZDriver vulnerability in HUAWEI Hisilicon TEE architecture. This paper presents MicroTEE, a TEE OS based on the microkernel architecture. In MicroTEE, the microkernel provides strong isolation for TEE OS's basic services, such as crypto service and platform key management service. The kernel is only responsible for providing core services such as address space management, thread management, and inter-process communication. Other fundamental services, such as crypto service and platform key management service are implemented as applications at the user layer. Crypto Services and Key Management are used to provide Trusted Applications (TAs) with sensitive information encryption, data signing, and platform attestation functions. Our design avoids the compromise of the whole TEE OS if only one kernel service is vulnerable. A monitor has also been added to perform the switch between the secure world and the normal world. Finally, we implemented a MicroTEE prototype on the Freescale i.MX6Q Sabre Lite development board and tested its performance. Evaluation results show that the performance of cryptographic operations in MicroTEE is better than it in Linux when the size of data is small.

Overview of System-Level Security Technologies based on ARM TrustZone

“…In contrast, the other isolated security world performs a small, trusted and secure operating system, as well as some advanced security management tasks developed by Trusted Application (TA). Within the TEE there can be TrustZonebased operating systems such as Qualcomm's QSEE [3], the open-source OPTEE [4], etc. that provide security services for security-sensitive applications.…”

Quick Boot of Trusted Execution Environment With Hardware Accelerators

“…HyperMI presents virtual machine protection, featuring security against compromised hypervisors by isolating guests in a secure execution environment [14]. MicroTEE designs a TEE on a microkernel software architecture with the necessary services for the application layer [15]. Ladjel et al evaluate the use of TEE-based computing for personal data in a large number of participants [16].…”