A secure and formally verified linux KVM hypervisor
Journal
Proceedings - IEEE Symposium on Security and Privacy
Journal Volume
2021-May
Pages
1782-1799
Date Issued
2021
Author(s)
Abstract
Commodity hypervisors are widely deployed to support virtual machines (VMs) on multiprocessor hardware. Their growing complexity poses a security risk. To enable formal verification over such a large codebase, we introduce microverification, a new approach that decomposes a commodity hypervisor into a small core and a set of untrusted services so that we can prove security properties of the entire hypervisor by verifying the core alone. To verify the multiprocessor hypervisor core, we introduce security-preserving layers to modularize the proof without hiding information leakage so we can prove each layer of the implementation refines its specification, and the top layer specification is refined by all layers of the core implementation. To verify commodity hypervisor features that require dynamically changing information flow, we introduce data oracles to mask intentional information flow. We can then prove noninterference at the top layer specification and guarantee the resulting security properties hold for the entire hypervisor implementation. Using microverification, we retrofitted the Linux KVM hypervisor with only modest modifications to its codebase. Using Coq, we proved that the hypervisor protects the confidentiality and integrity of VM data, while retaining KVM's functionality and performance. Our work is the first machine-checked security proof for a commodity multiprocessor hypervisor. ? 2021 IEEE.
Subjects
Linux
Multiprocessing systems
Specifications
Theorem proving
Hiding informations
Hypervisors
Information flows
Multi-processor hardware
New approaches
Security proofs
Security properties
Security risks
Virtual machine
Type
conference paper