Section: New Results
Virtual machine (VM)
Participant : Bertil Folliot.
Our research interest are in computer systems, particularly operating systems and virtual machines. We focus on resource management, isolation and concurrency management in virtual machines. Since September 2008, we started with Gilles Muller a new complementary research theme on dynamic patches of operating systems.
Virtual machines
Isolation in OSGi: The OSGi framework is a Java-based, centralized, component oriented platform. It is being widely adopted as an execution environment for the development of extensible applications. However, current Java Virtual Machines are unable to isolate components from each other's. By modifying shared variables or allocating too much memory, a malicious component can freeze the complete platform. I work on I-JVM, a Java Virtual Machines that provides a lightweight approach to isolation while preserving the compatibility with legacy OSGi applications. Our evaluation of I-JVM shows that it solves the 15 known OSGi vulnerabilities due to the Java Virtual Machine with an overhead below 20% . I-JVM has been presented in DSN 2009.
VMKit: Managed Runtime Environments (MREs), such as the JVM and the CLI, form an attractive environment for program execution, by providing portability and safety, via the use of a bytecode language and automatic memory management, as well as good performance, via just-in-time (JIT) compilation. Nevertheless, developing such a fully featured MRE, including features such as a garbage collector and JIT compiler, is a herculean task. As a result, new languages cannot easily take advantage of the benefits of MREs, and it is difficult to experiment with extensions of existing MRE based languages. VMKit is a first attempt to build a common substrate that eases the development of high-level MREs. We have successfully used VMKit to build two MREs: a Java Virtual Machine (J3) and a Common Language Runtime (N3). VMKit has performance comparable to the well established open source MREs Cacao, Apache Harmony and Mono. VMKit is freely distributed under the LLVM licence with the LLVM framework developed by the University of Illinois at Urbana-Champaign and now maintained by Apple. Nicolas Geoffray has defended his PhD thesis in September on the subject.
Semantic patches
Open source infrastructure software, such as the Linux operating system, Web browsers and n-tier servers, has become a well-recognized solution for implementing critical functions of modern life. Furthermore, companies and local governments are finding that the use of open source software reduces costs and allows them to pool their resources to build and maintain infrastructure software in critical niche areas. Nevertheless, the increasing reliance on open source infrastructure software introduces new demands in terms of security and safety. In principle, infrastructure software contains security features that protect against data loss, data corruption, and inadvertent transmission of data to third parties. In practice, however, these security features are compromised by a simple fact: software contains bugs.
We are developing a comprehensive solution to the problem of finding bugs in API usage in open source infrastructure software based on our experience in using the Coccinelle code matching and transformation tool, and our interactions with the Linux community. Coccinelle targets the problem of documenting and automating collateral evolutions in C code, specifically Linux code. A collateral evolution is a change that is needed in the clients of an API when the API changes in some way that affects its interface. Coccinelle provides a language for expressing collateral evolutions by means of Semantic Patches, and a transformation tool for performing them automatically. Recently, we have begun using Coccinelle to generate traditional patches for improving the safety of Linux. Some Linux developers have also begun to use the tool. Over 170 of these patches developed using Coccinelle have been integrated into the mainline Linux kernel, and more have been accepted by Linux maintainers and are pending integration. Our current work is to build on the results of Coccinelle by designing libraries of semantic patches to identify API protocols and detect violations in their usage. One of the novelty of this work is to explore how to develop these semantic patches in collaborative manner with the community of Linux open-source developers as a target. In this context, we will investigate the usage of the Telex framework for supporting collaborative developments.
