WASM sandboxes don't do much to guarantee the soundness of your program. It can hose your memory all it wants, it can just only do so within the confines of the sandbox.
Using a sandbox also limits what you can do with a system. With stuff like SECCOMP you have to methodically define policies for all its interactions. Like you're dealing with two systems. It's very bureaucratic and the reason we do it, is because we don't trust our programs to behave.
With Fil-C you get a different approach. The language and runtime offer a stronger level of assurance your program can only behave, so you can trust it more to have unfettered access to the actual system. You also have the choice to use Fil-C with a sandbox like SECCOMP as described in the blog post, since your Fil-C binaries are just normal executables that can access powerful Linux APIs like prctl. It took Linux twenty years to invent that interface, so you'll probably have to wait ten years to get something comparable from WASI.
> It can hose your memory all it wants, it can just only do so within the confines of the sandbox.
True, although as I understand it the WASI component model at least allows multiple fine-grained sandboxes, so it's somewhere in-between per-object capabilities and one big sandbox for your entire program. I haven't actually used it yet so I might be wrong about that.
> so you'll probably have to wait ten years to get something comparable from WASI
I think for many WASI use cases the capability control would be done by the host program itself, so you don't need OS-level support for it. E.g. with Wasmtime I do
WASI is basically CORBA, and DCOM, PDO for newer generations.
Or if you prefer the bytecode based evolution of them, RMI and .NET Remoting.
I don't see it going that far.
The WebAssembly development experience on the browser mostly still sucks, especially the debugging part, and on the server it is another yet another bytecode.
Finally, there is hardly any benefit over OS processes, talking over JSON-RPC (aka how REST gets mostly used), GraphQL, gRPC, or plain traditional OS IPC.
You've named half of the weasel security technologies of the last three decades. The nice thing about SECCOMP BPF is it's so difficult to use that you get the comfort of knowing that only a very enlightened person could have written your security policy. Hell is being subjected to restrictions defined by people with less imagination than you.
WASM sacrifices guest security & performance in order to provide mediocre host sandboxing, though. It might be a useful tradeoff sometimes, but proper process-based sandboxing is so much stronger and lets the guest also have full security & performance.
How is process-based sandboxing stronger? Also the performance penalty is not only due to sandboxing (I doubt it's even mostly due to it). Likely more significant is the portability.
Because the guarantees themselves are stronger, process isolation is something we have decades of experience with, it goes wrong every now and then but those are rare instances whereas what amounts to application level isolation is much weaker in terms the guarantees it that it provides and the maturity level of the code. That suggests that if you base your isolation scheme on processes rather than 'just' sandboxing that you will come out ahead and even with all other things the same you'd have one more layer in your stack of swiss cheese slices. A VM would offer another layer of protection on top of that, one with yet stronger guarantees.
process-based sandboxing has hardware support and thus stronger defenses against things like spectre. So far every CPU on the market has only elected to address spectre as it relates to crossing ring or process boundaries. Nobody has added hardware spectre defenses for in-process sandboxing. Also, process-based sandboxing allows the guest to also have a full suite of security protections like ASLR. If you are doing sandboxing for defense in depth, reducing the security of what's inside the guest in turn reduces the security of your entire chain.
And I didn't say the performance penalty was because of sandboxing (although in the case of WASM there is cost as it's doing software enforcement of things that otherwise are "for free" in hardware), but just that WASM has a performance cost compared to native. If you are using WASM just for sandboxing, you still then pay a performance cost for portability you didn't need.
No because the host can present the same interface on every platform. I do think that WASI is waaay to much "let's just copy POSIX and screw other platforms", but it does work pretty well even on Windows.
Using a sandbox also limits what you can do with a system. With stuff like SECCOMP you have to methodically define policies for all its interactions. Like you're dealing with two systems. It's very bureaucratic and the reason we do it, is because we don't trust our programs to behave.
With Fil-C you get a different approach. The language and runtime offer a stronger level of assurance your program can only behave, so you can trust it more to have unfettered access to the actual system. You also have the choice to use Fil-C with a sandbox like SECCOMP as described in the blog post, since your Fil-C binaries are just normal executables that can access powerful Linux APIs like prctl. It took Linux twenty years to invent that interface, so you'll probably have to wait ten years to get something comparable from WASI.