VeriWasm: SFI safety for native-compiled Wasm

This repository contains all the code and data necessary for building VeriWasm and reproducing the results presented in our NDSS'21 paper Доверя́й, но проверя́й: SFI safety for native-compiled Wasm.

Abstract

WebAssembly (Wasm) is a platform-independent bytecode that offers both good performance and runtime isolation. To implement isolation, the compiler inserts safety checks when it compiles Wasm to native machine code. While this approach is cheap, it also requires trust in the compiler's correctness—trust that the compiler has inserted each necessary check, correctly formed, in each proper place. Unfortunately, subtle bugs in the Wasm compiler can break—and have broken—isolation guarantees. To address this problem, we propose verifying memory isolation of Wasm binaries post-compilation. We implement this approach in VeriWasm, a static offline verifier for native x86-64 binaries compiled from Wasm; we prove the verifier's soundness, and find that it can detect bugs with no false positives. Finally, we describe our deployment of VeriWasm at Fastly.

Build VeriWasm

You first need to install several dependencies:

Once you have these, you can build VeriWasm:

bash git submodule update --init --recursive cargo build --release

Run VeriWasm

To run VeriWasm on your own binaries, you just need to point it to the module you want to check:

bash cargo run --release -- -i <input path>

Usage:

``` VeriWasm 0.1.0 Validates safety of native Wasm code

USAGE: veriwasm [FLAGS] [OPTIONS] -i

FLAGS: -h, --help Prints help information -q, --quiet
-V, --version Prints version information

OPTIONS: -j, --jobs Number of parallel threads (default 1) -i path to native Wasm module to validate -o, --output Path to output stats file ```

Reproducing evaluation results

This repo contains all the infrastructure necessary for reproducing the results described in the paper. Once you build VeriWasm you can run our tests and and performance benchmarks.

Running the evaluation suite

To verify all the binaries described in the paper, except the SPEC CPU 2006 binaries (they are proprietary) and the Fastly production binaries, run:

bash git clone https://github.com/PLSysSec/veriwasm_public_data.git cd veriwasm_public_data && sh setup.sh && sh build_negative_tests.sh && cd .. cargo test --release

To get get the performance statistics for the binaries, run:

bash make compute_stats python3 graph_stats.py stats/*

Fuzzing VeriWasm

To fuzz VeriWasm, you'll need to install cmake and then build the fuzzers (and the tooling they rely on):

bash make build_fuzzers

Then, either run the Csmith-based fuzzer:

bash cd veriwasm_fuzzing make csmith_fuzz

or the Wasm-based fuzzer:

bash cd veriwasm_fuzzing make wasm_fuzz

By default, make will use four cores; you may want to change this.

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