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This paper introduces PRISM, a novel TEE architecture that utilizes prismatic capabilities to create lightweight userspace enclaves while overcoming the limitations of traditional CHERI-based TEEs, such as expensive capability revocation and domain transitions. By binding enclave identifiers to physical memory access controls, PRISM achieves efficient ownership establishment and supports remote attestation, significantly enhancing memory safety and operational efficiency. The experimental results indicate that PRISM incurs only moderate overhead (≤ 15%) compared to Intel SGX, marking a substantial advancement in TEE performance and usability.
PRISM achieves efficient enclave isolation with only 15% overhead, outperforming traditional Intel SGX while enhancing memory safety and remote attestation capabilities.
Trusted execution environments (TEEs) protect sensitive code and data from external interference, but lack inherent memory safety. CHERI can enforce spatial memory safety at the object level. Attempts to establish a TEE using CHERI primitives suffer from (1) expensive capability revocation operations, (2) need to rely on the host operating system (OS) to support provenance tracking and physical memory protection, (3) expensive domain transitions, and (4) lack of support for remote attestation. We introduce prismatic capabilities and present PRISM, a TEE architecture for CHERI leveraging prismatic capabilities to create userspace enclaves while addressing these challenges. PRISM binds enclave'hues'(identifiers) in prismatic capabilities to physical memory access controls, enables O(1) ownership establishment without memory sweeps, and supports efficient domain transitions that atomically activate and deactivate prismatic capabilities. Additionally, PRISM enables remote attestation of its enclaves. We demonstrate that execution of userspace enclaves in PRISM incurs only moderate overhead (<= 15%), a significant improvement over the same workloads under Intel SGX
