alt Hacker NewsRight - I trust workerd in the context of Cloudflare because I know it has a team of people who's job it is to keep it secure who are on-call 24/7.
The problem I have is that I'm just one person and I don't want to be on call 24/7 ready to react to sandbox escapes, so I'm hoping I can find a solution that someone else built where they are willing to say "this is safe: you can feed in a string of untrusted JavaScript and we are confident it won't break out again".
I think I might be able to get there via WebAssembly (e.g. with QuickJS or MicroQuickJS compiled to WASM) because the whole point of WebAssembly is to solve this one problem.
> But if you're not literally accepting code directly from anonymous internet users then the risk may be a lot lower
That's the problem: this is exactly what I want to be able to do!
I want to build extension systems for my own apps such that users can run their own code or paste in code written by other people and have it execute safely. Similar to Shopify Functions: https://shopify.dev/docs/apps/build/functions
I think the value unlocked by this kind of extension mechanism is ready to skyrocket, because users can use LLMs to help write that code for them.
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> the whole point of WebAssembly is to solve this one problem.
For Wasm to be a secure sandbox, you have to assume a bug-free compiler/interpreter, which, alas, none of them really are. It's a somewhat easier problem than building a bug-free JavaScript runtime, but not by as much as you might expect, sadly.
> I want to build extension systems for my own apps such that users can run their own code or paste in code written by other people and have it execute safely. Similar to Shopify Functions: https://shopify.dev/docs/apps/build/functions
Ah, this is exactly the Workers for Platforms use case: https://developers.cloudflare.com/cloudflare-for-platforms/w...
And indeed, Shopify uses it: https://shopify.engineering/how-we-built-oxygen
(There's also the upcoming Dynamic Worker Loader API: https://developers.cloudflare.com/workers/runtime-apis/bindi...)
But it sounds like you really do want to self-host? I don't blame you, but that does make it tough. I'm not sure there's any such thing as a secure sandbox that doesn't require some level of monitoring and daily maintenance, sadly. (But admittedly I may be biased.)
You need more than a simple sandbox for what you describe. You also need to avoid infinite loops or other constructs from causing a DoS or similar, and if you are doing this with the intention of interacting with some other parts of a system then you need to think about how that interaction works and whether there is a way to execute something outside of that sandbox.
Even if you go with something backed by a full time team there is still going to be a chance you have to deal with a security issue in a hurry, maybe in the run up to Christmas. That is just going to come with the territory and if you don’t want to deal with that then you probably need to think about whether you really need a sandbox that can execute untrusted code.
I worked on a sandbox of Hermes that compiles the engine to wasm, and then converts the wasm to C (like Mozilla's RLBox). It exposes the same C++ API as Hermes so it is pretty convenient to drop in, and should be fairly secure.
It hasn't been updated in some time, but it should still be working, and can probably be brought up to date with some small effort: https://github.com/facebook/hermes/tree/static_h/API/hermes_...
EDIT: Reading some of your other comments, I should point out that this is more like a component of a possible solution. It does not attempt to prevent resource exhaustion or crashes due to corrupted internal state.
Wait, why not just actually use the Cloudflare Sandboxes product then? Is it too costly or something? Or you need to be able to run without a connection to their cloud?
There's also JCO for creating JS based WebAssembly components. It's based on StarlingMonkey which I believe is slightly faster than QuickJS under web assembly. https://github.com/bytecodealliance/jco
Benchmark numbers for request isolated JS hello world / React page rendering:
Numbers taken from our upcoming TinyKVM paper. Benchmark setup code for JCO/wasmtime is here: https://github.com/libriscv/kvmserver/tree/main/examples/was...(I suspect even if we are able to get TinyKVM into a state you'd feel comfortable with in the future it would still be an awkward fit for Datasette since nested virtualisation is not exposed on AWS EC2.)