Automatic Transformation of Bit-Level C Code to Support Multiple Equivalent Data Layouts

Nita, Marius; Grossman, Dan

doi:10.1007/978-3-540-78791-4_6

Cited by 6 publications

(3 citation statements)

References 18 publications

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“…Because of this dynamically-checked, physical subtyping, pointer-to-pointer casts can be treated as the identity. Similar ideas arise in other formalizations of low-level language semantics [24,25].…”

Section: The Llvm Flattened Values and Memory Accessessupporting

confidence: 63%

Formalizing the LLVM intermediate representation for verified program transformations

Zhao

Nagarakatte

Martin

et al. 2012

Proceedings of the 39th Annual ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages

117

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This paper presents Vellvm (verified LLVM), a framework for reasoning about programs expressed in LLVM's intermediate representation and transformations that operate on it. Vellvm provides a mechanized formal semantics of LLVM's intermediate representation, its type system, and properties of its SSA form. The framework is built using the Coq interactive theorem prover. It includes multiple operational semantics and proves relations among them to facilitate different reasoning styles and proof techniques. To validate Vellvm's design, we extract an interpreter from the Coq formal semantics that can execute programs from LLVM test suite and thus be compared against LLVM reference implementations. To demonstrate Vellvm's practicality, we formalize and verify a previously proposed transformation that hardens C programs against spatial memory safety violations. Vellvm's tools allow us to extract a new, verified implementation of the transformation pass that plugs into the real LLVM infrastructure; its performance is competitive with the nonverified, ad-hoc original. Disciplines Computer SciencesComments Zhao, J., Nagarakatte, S., Martin, M., & Zdancewic, S., Formalizing the LLVM Intermediate Representation for Verified Program Transformations, 39th ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages, Jan. 2012, doi: 10.1145/2103656.2103709 © 1994, 1995, 1998, 2002, 2009 by ACM, Inc. Permission to copy and distribute this document is hereby granted provided that this notice is retained on all copies, that copies are not altered, and that ACM is credited when the material is used to form other copyright policies. To validate Vellvm's design, we extract an interpreter from the Coq formal semantics that can execute programs from LLVM test suite and thus be compared against LLVM reference implementations. To demonstrate Vellvm's practicality, we formalize and verify a previously proposed transformation that hardens C programs against spatial memory safety violations. Vellvm's tools allow us to extract a new, verified implementation of the transformation pass that plugs into the real LLVM infrastructure; its performance is competitive with the non-verified, ad-hoc original.

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Section: The Llvm Flattened Values and Memory Accessessupporting

confidence: 63%

Formalizing the LLVM intermediate representation for verified program transformations

Zhao

Nagarakatte

Martin

et al. 2012

Proceedings of the 39th Annual ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages

117

View full text Add to dashboard Cite

show abstract

“…This includes techniques for adapter specification [46], for component adaptation using formal specifications of components [39], [42], [43], [60], [5]. Component adaptation has also been performed at the Java bytecode level [30], as well as the C bitcode level [40]. Behavior sampling [44] is a similar area of research for finding equivalence over a small set of input samples.…”

Section: Component Adaptationmentioning

confidence: 99%

Finding Substitutable Binary Code By Synthesizing Adapters

Sharma

Hietala

McCamant

2021

IIEEE Trans. Software Eng.

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Independently developed codebases typically contain many segments of code that perform same or closely related operations (semantic clones). Finding functionally equivalent segments enables applications like replacing a segment by a more efficient or more secure alternative. Such related segments often have different interfaces, so some glue code (an adapter) is needed to replace one with the other. We present an algorithm that searches for replaceable code segments at the function level by attempting to synthesize an adapter between them from some family of adapters; it terminates if it finds no possible adapter. We implement our technique using (1) concrete adapter enumeration based on Intel's Pin framework (2) binary symbolic execution, and explore the relation between size of adapter search space and total search time. We present examples of applying adapter synthesis for improving security and efficiency of binary functions, deobfuscating binary functions, and switching between binary implementations of RC4. We present two large-scale evaluations, (1) we run adapter synthesis on more than 13,000 function pairs from the Linux C library, (2) using more than 61,000 fragments of binary code extracted from a ARM image built for the iPod Nano 2g device and known functions from the VLC media player, we evaluate our adapter synthesis implementation on more than a million synthesis tasks . Our results confirm that several instances of adaptably equivalent binary functions exist in real-world code, and suggest that adapter synthesis can be applied for reverse engineering and for constructing cleaner, less buggy, more efficient programs.

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“…In our own prior work [17], we designed a small extension to the C language that allows programmers to eliminate subsets of the program that are used to handle alternative data layouts (e.g., little-vs. big-endian) by using a declarative mapping language to specify how one layout relates to another. Then, the alternatives are automatically generated.…”

Section: Related Workmentioning

confidence: 99%

Using twinning to adapt programs to alternative APIs

Nita

Notkin

2010

Proceedings of the 32nd ACM/IEEE International Conference on Software Engineering - Volume 1

Self Cite

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We describe twinning and its applications to adapting programs to alternative APIs. Twinning is a simple technique that allows programmers to specify a class of program changes, in the form of a mapping, without modifying the target program directly. Using twinning, programmers can specify changes that transition a program from using one API to using an alternative API.We describe two related mapping-based source-to-source transformations. The first applies the mapping to a program, producing a copy with the changes applied. The second generates a new API that abstracts the changes specified in the mapping. Using this API, programmers can invoke either the old (replaced) code or the new (replacement) code through a single interface.Managing program variants usually involves heavyweight tasks that can prevent the program from compiling for extended periods of time, as well as simultaneous maintenance of multiple implementations, which can make it easy to forget to add features or to fix bugs symmetrically. Our main contribution is to show that, at least in some common cases, the heavyweight work can be reduced and symmetric maintenance can be at least encouraged, and often enforced.

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Automatic Transformation of Bit-Level C Code to Support Multiple Equivalent Data Layouts

Cited by 6 publications

References 18 publications

Formalizing the LLVM intermediate representation for verified program transformations

Formalizing the LLVM intermediate representation for verified program transformations

Finding Substitutable Binary Code By Synthesizing Adapters

Using twinning to adapt programs to alternative APIs

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