An Embedded System I/O Isolation Technology for Raspberry Pi

Nowadays user’s data in devices is at high risk. To ensure security of program’s runtime environment, Trusted Computing and Trusted Execution Environment(TEE) are proposed, which construct trusted base at the hardware level. Hardware vendors implement hardware trusted base for their new products, Intel’s Software Guard eXtension(SGX) as an example. SGX lacks isolation for device I/O so there are many SGX-based mechanisms proposed that add protection for device I/O. However, all the above trusted mechanisms must be based on that the CPU has extensions for trusted computing, which means that lots of devices equipped with old chips and those embedded devices on other ISA like Arm and RISC-V have no possibility to support this trusted computing mechanism. Therefore, we proposes an I/O isolation technology for embedded devices and implements a trusted computing mechanism named XiRang(eXtended I/O Reliable Authentication Guard) for Raspberry Pi. Specifically, we do the following work. (1) Use an external trusted device as the physical trusted root for embedded devices, which made up for the lack of trusted computing extension of their chips. (2) On the premise of trusted hardware, XiRang realizes the trusted isolation of USB disk, uses trusted Linux container as the application runtime environment, and completes the trusted chain transfer from the external trusted device to the application. (3) Finally, we evaluate performance of XiRang.