Time Protection

Timing channels enable data leakage that threatens the security of computer systems, from cloud platforms to smartphones and browsers executing untrusted third-party code. Preventing unauthorised information flow is a core duty of the operating system, however, present OSes are unable to prevent timing channels. We argue that OSes must provide time protection, the temporal equivalent of the established memory protection, for isolating security domains. We examine the requirements of time protection, present a design and its implementation in the seL4 microkernel, and evaluate efficacy and cost on x86 and Arm processors.