Rethinking Isolation Mechanisms for Datacenter Multitenancy

Authors: 

Varun Gandhi and James Mickens, Harvard University

Abstract: 

In theory, trusted execution environments like SGX are promising approaches for isolating datacenter tenants. In practice, the associated hardware primitives suffer from three major problems: side channels induced by microarchitectural co-tenancy; weak guarantees for post-load software integrity; and opaque hardware implementations which prevent third-party security auditing. We explain why these limitations are so problematic for datacenters, and then propose a new approach for trusted execution. This approach, called IME (Isolated Monitor Execution) provides SGX-style memory encryption, but strictly prevents microarchitectural co-tenancy of secure and insecure code. IME also uses a separate, microarchitecturally-isolated pipeline to run dynamic security checks on monitored code, enabling post-load monitoring for security invariants like CFI or type safety. Finally, an IME processor exports a machine-readable description of its microarchitectural implementation, allowing tenants to reason about the security properties of a particular IME instance.

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BibTeX
@inproceedings {254140,
author = {Varun Gandhi and James Mickens},
title = {Rethinking Isolation Mechanisms for Datacenter Multitenancy},
booktitle = {12th {USENIX} Workshop on Hot Topics in Cloud Computing (HotCloud 20)},
year = {2020},
url = {https://www.usenix.org/conference/hotcloud20/presentation/gandhi},
publisher = {{USENIX} Association},
month = jul,
}

Presentation Video