Firefox is mostly written in C and C++. These languages are notoriously difficult to use safely, since any mistake can lead to complete compromise of the program.

The team has thus far had 2 strategies for securing the codebase, breaking code into multiple sandboxed processes with reduced privileges and rewriting code in a safe language like Rust.

today, we’re adding a third approach to our arsenal. RLBox, a new sandboxing technology developed by researchers at the University of California, San Diego, the University of Texas, Austin, and Stanford University, allows us to quickly and efficiently convert existing Firefox components to run inside a WebAssembly sandbox.

This strikes me as a bonkers idea and kinda brilliant.

The core implementation idea behind wasm sandboxing is that you can compile C/C++ into wasm code, and then you can compile that wasm code into native code for the machine your program actually runs on.

Click through to read more about how they’re pulling this off.