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Device-agnostic Firmware Execution is Possible: A Concolic Execution Approach for Peripheral Emulation
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Network verification often requires analyzing properties across different spaces (header space, failure space, or their product) under different failure models (deterministic and/or probabilistic). Existing verifiers efficiently cover the header or failure space, but not both, and efficiently reason about deterministic or probabilistic failures, but not both. Consequently, no single verifier can support all analyses that require different space coverage and failure models. This paper introduces Symbolic Router Execution (SRE), a general and scalable verification engine that supports various analyses. SRE symbolically executes the network model to discover what we call packet failure equivalence classes (PFECs), each of which characterises a unique forwarding behavior across the product space of headers and failures. SRE enables various optimizations during the symbolic execution, while remaining agnostic of the failure model, so it scales to the product space in a general way. By using BDDs to encode symbolic headers and failures, various analyses reduce to graph algorithms (e.g., shortest-path) on the BDDs. Our evaluation using real and synthetic topologies show SRE achieves better or comparable performance when checking reachability, mining specifications, etc. compared to state-of-the-art methods.more » « less
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null (Ed.)Faceted execution is a linguistic paradigm for dynamic information-flow control with the distinguishing feature that program values may be faceted. Such values represent multiple versions or facets at once, for different security labels. This enables policy-agnostic programming: a paradigm permitting expressive privacy policies to be declared, independent of program logic. Although faceted execution prevents information leakage at runtime, it does not guarantee the absence of failure due to policy violations. By contrast with static mechanisms (such as security type systems), dynamic information-flow control permits arbitrarily expressive and dynamic privacy policies but imposes significant runtime overhead and delays discovery of any possible violations. In this paper, we present the two different abstract interpretations for faceted execution in the presence of first-class policies. We first present an abstraction which allows one to reason statically about the shape of facets at each program point. This abstraction is useful for statically proving the absence of runtime errors and eliminating runtime checks related to facets. Reasoning statically about the contents of faceted values, however, is complicated by the presence of first-class security labels, especially because abstract labels may conflate more than one runtime label. To address these issues, we also develop a more precise abstraction that relies on an analysis tracking singleton heap abstractions. We present an implementation of our coarse abstraction in Racket and demonstrate its performance on several sample programs. We conclude by showing how our precise domain can be used to verify information-flow properties.more » « less
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3427228.3427280
