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Documents authored by Dockins, Robert

Document
Invited Talk
DOI: 10.4230/LIPIcs.ITP.2026.1
Nitro Isolation Engine: Formally Verifying a Production Hypervisor (Invited Talk)

Authors: Hanno Becker, Nathan Chong, Robert Dockins, Jim Grundy, Jason Hu, Ike Mulder, Dominic P. Mulligan, Paul Mure, Bryan Parno, Lawrence C. Paulson, and Konrad Slind

Published in: LIPIcs, Volume 382, 17th International Conference on Interactive Theorem Proving (ITP 2026)

Abstract
Cloud computing relies on hypervisors to enforce isolation between co-tenanted virtual machines. Hypervisors are therefore critical security infrastructure, and assurance of their correctness is paramount. Traditional engineering techniques - code review, testing, fuzzing - provide strong assurance but cannot exhaustively verify that isolation holds across all possible execution paths. Formal verification extends and complements these approaches by establishing mathematical guarantees about system behaviour. This talk presents our experience applying interactive theorem proving to verify a production hypervisor component: the Nitro Isolation Engine. This is a trusted, minimalist computing base written in Rust, enforcing isolation between virtual machines on AWS Graviton5 EC2 instances. Designed for verification from inception, we have specified the intended behaviour of this component and verified correctness in the Isabelle/HOL interactive theorem prover, producing approximately 330,000 lines of machine-checked models and proofs, and establishing three key classes of property: 1) Functional correctness: The system behaves as specified for all operations including virtual machine creation, memory mapping, and abort handling. Our total verification approach additionally establishes memory-safety, termination, and absence of runtime errors. 2) Confidentiality: A noninterference-style property demonstrates that guest virtual machine state remains hidden from an expansive definition of observer monitoring system actions, formalised as indistinguishability preservation up to permitted declassification flows. 3) Integrity: Guest virtual machine private state is unaffected by operations on distinct virtual machines. Currently, our proof coverage extends to verification of the core virtual machine-management hypercalls, guest power management, various utility hypercalls, and a subset of data, instruction, and asynchronous abort handling, and will continue to expand to cover more functionality including PCI device management and virtual GIC (Generic Interrupt Controller) handling. The talk will discuss the verification approach, key proof techniques, and challenges in applying formal methods to production systems. Note that this work builds on decades of academic research across interactive theorem proving, formal specification, separation logic and its automation, and programming language semantics.
Cite as

Hanno Becker, Nathan Chong, Robert Dockins, Jim Grundy, Jason Hu, Ike Mulder, Dominic P. Mulligan, Paul Mure, Bryan Parno, Lawrence C. Paulson, and Konrad Slind. Nitro Isolation Engine: Formally Verifying a Production Hypervisor (Invited Talk). In 17th International Conference on Interactive Theorem Proving (ITP 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 382, pp. 1:1-1:2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{becker_et_al:LIPIcs.ITP.2026.1,
  author =	{Becker, Hanno and Chong, Nathan and Dockins, Robert and Grundy, Jim and Hu, Jason and Mulder, Ike and Mulligan, Dominic P. and Mure, Paul and Parno, Bryan and Paulson, Lawrence C. and Slind, Konrad},
  title =	{{Nitro Isolation Engine: Formally Verifying a Production Hypervisor}},
  booktitle =	{17th International Conference on Interactive Theorem Proving (ITP 2026)},
  pages =	{1:1--1:2},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-436-9},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{382},
  editor =	{Komendantskaya, Ekaterina and Nipkow, Tobias},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITP.2026.1},
  URN =		{urn:nbn:de:0030-drops-269757},
  doi =		{10.4230/LIPIcs.ITP.2026.1},
  annote =	{Keywords: Isabelle/HOL, Rust, verification, separation logic, hypervisors}
}
Document
DOI: 10.4230/DagSemProc.10351.3
A Theory of Termination via Indirection

Authors: Robert Dockins and Aquinas Hobor

Published in: Dagstuhl Seminar Proceedings, Volume 10351, Modelling, Controlling and Reasoning About State (2010)

Abstract
Step-indexed models provide approximations to a class of domain equations and can prove type safety, partial correctness, and program equivalence; however, a common misconception is that they are inapplicable to liveness problems. We disprove this by applying step-indexing to develop the first Hoare logic of total correctness for a language with function pointers and semantic assertions. In fact, from a liveness perspective, our logic is stronger: we verify explicit time resource bounds. We apply our logic to examples containing nontrivial "higher-order" uses of function pointers and we prove soundness with respect to a standard operational semantics. Our core technique is very compact and may be applicable to other liveness problems. Our results are machine checked in Coq.
Cite as

Robert Dockins and Aquinas Hobor. A Theory of Termination via Indirection. In Modelling, Controlling and Reasoning About State. Dagstuhl Seminar Proceedings, Volume 10351, pp. 1-12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{dockins_et_al:DagSemProc.10351.3,
  author =	{Dockins, Robert and Hobor, Aquinas},
  title =	{{A Theory of Termination via Indirection}},
  booktitle =	{Modelling, Controlling and Reasoning About State},
  pages =	{1--12},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2010},
  volume =	{10351},
  editor =	{Amal Ahmed and Nick Benton and Lars Birkedal and Martin Hofmann},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.10351.3},
  URN =		{urn:nbn:de:0030-drops-28050},
  doi =		{10.4230/DagSemProc.10351.3},
  annote =	{Keywords: Step-indexed Models, Termination}
}
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