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Tal Garfinkel

Publications and source records attributed to Tal Garfinkel.

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ARM MTE Performance in Practice (Extended Version)

We present the first comprehensive analysis of ARM MTE hardware performance on four different microarchitectures: ARM Big (A7x), Little (A5x), and Performance (Cortex-X) cores on the Google Pixel 8 and Pixel 9, and on Ampere Computing's AmpereOne CPU core. We also include preliminary analysis of MTE on Apple's M5 chip. We investigate performance in MTE's primary application -- probabilistic memory safety -- on both SPEC CPU benchmarks and in server workloads such as RocksDB, Nginx, PostgreSQL, and Memcached. While MTE often exhibits modest overheads, we also see performance slowdowns up to 6.64x on certain benchmarks. We identify the microarchitectural cause of these overheads and where they can be addressed in future processors. We then analyze MTE's performance for more specialized security applications such as memory tracing, time-of-check time-of-use prevention, sandboxing, and CFI. In some of these cases, MTE offers significant advantages today, while the benefits for other cases are negligible or will depend on future hardware. Finally, we explore where prior work characterizing MTE performance has either been incomplete or incorrect due to methodological or experimental errors.

cs.CR

Retrofitting Fine Grain Isolation in the Firefox Renderer (Extended Version)

Firefox and other major browsers rely on dozens of third-party libraries to render audio, video, images, and other content. These libraries are a frequent source of vulnerabilities. To mitigate this threat, we are migrating Firefox to an architecture that isolates these libraries in lightweight sandboxes, dramatically reducing the impact of a compromise. Retrofitting isolation can be labor-intensive, very prone to security bugs, and requires critical attention to performance. To help, we developed RLBox, a framework that minimizes the burden of converting Firefox to securely and efficiently use untrusted code. To enable this, RLBox employs static information flow enforcement, and lightweight dynamic checks, expressed directly in the C++ type system. RLBox supports efficient sandboxing through either software-based-fault isolation or multi-core process isolation. Performance overheads are modest and transient, and have only minor impact on page latency. We demonstrate this by sandboxing performance-sensitive image decoding libraries ( libjpeg and libpng ), video decoding libraries ( libtheora and libvpx ), the libvorbis audio decoding library, and the zlib decompression library. RLBox, using a WebAssembly sandbox, has been integrated into production Firefox to sandbox the libGraphite font shaping library.

cs.CR

Gobi: WebAssembly as a Practical Path to Library Sandboxing

Software based fault isolation (SFI) is a powerful approach to reduce the impact of security vulnerabilities in large C/C++ applications like Firefox and Apache. Unfortunately, practical SFI tools have not been broadly available. Developing SFI toolchains are a significant engineering challenge. Only in recent years have browser vendors invested in building production quality SFI tools like Native Client (NaCl) to sandbox code. Further, without committed support, these tools are not viable, e.g. NaCl has been discontinued, orphaning projects that relied on it. WebAssembly (Wasm) offers a promising solution---it can support high performance sandboxing and has been embraced by all major browser vendors---thus seems to have a viable future. However, Wasm presently only offers a solution for sandboxing mobile code. Providing SFI for native application, such as C/C++ libraries requires additional steps. To reconcile the different worlds of Wasm on the browser and native platforms, we present Gobi. Gobi is a system of compiler changes and runtime support that can sandbox normal C/C++ libraries with Wasm---allowing them to be compiled and linked into native applications. Gobi has been tested on libjpeg, libpng, and zlib. Based on our experience developing Gobi, we conclude with a call to arms to the Wasm community and SFI research community to make Wasm based module sandboxing a first class use case and describe how this can significantly benefit both communities. Addendum: This short paper was originally written in January of 2019. Since then, the implementation and design of Gobi has evolved substantially as some of the issues raised in this paper have been addressed by the Wasm community. Nevertheless, several challenges still remain. We have thus left the paper largely intact and only provide a brief update on the state of Wasm tooling as of November 2019 in the last section.

cs.CR