Comment by olivierduval | Hacker News Reader

Comment by olivierduval | Hacker News Reader

> Most crates I use - like human-size or serde don't need any special capabilities to work. So we don't need to worry so much about their authors "turning evil" and adding malicious code to our software

well... :-(

Actually, it's obvious that some authors might "turn evil" dumbly, by abusing some kind of priviledged permissions. By chance, these kinds of supply-chain risks are "easily" identified because

1) the permissions are an "easy" risk indicator, so you can priorize either to pin the version library (after validating it) or validate the new version

2) not so many libraries will use these permissions so you "have time" to focus on them

3) in these libraries, the permissions will tell you what system call/bad effects is possible, so will allow you to narrow even more the scope of investigation

So, IMHO, permissions are not really the end of all but only a tiny step.

The real problem is "how can human-size be used to subvert the program ?" For example: what is happening if the returned size "forget" or "add" 100 bytes to files bigger than 1 KB ? As a remininder, STUXNET was about some speed a tiny bit faster than planned and shown...

Author here. Even if the permission system needs to be explicitly enabled and most people don't enable it, that would still have the effect of adding an early warning system for the entire rust ecosystem.

> The real problem is "how can human-size be used to subvert the program ?" For example: what is happening if the returned size "forget" or "add" 100 bytes to files bigger than 1 KB ? As a remininder, STUXNET was about some speed a tiny bit faster than planned and shown...

I read this argument in a similar vein to the argument against rust's unsafe blocks. "Look, C code will always need some amount of unsafe. So why bother sandboxing it?"

But in practice, having explicit unsafe blocks has been a massive win for safety in the language. You can opt out of it at any time - but most people never need to!

A 90% solution doesn't solve the problem entirely. But it does solve 90% of the problem. And thats pretty bloody good if you ask me! Sure - my safe rust decompression library could still maliciously inject code in files that it decompresses. But having checks like this would still reduce the security surface area by a huge amount.

Less implicit trust in random crate authors is a good thing. I don't want thousands of crate authors to be allowed to execute totally arbitrary code on my machine! The current situation is ridiculous.

Is there a known ratio of crates that use unsafe to ones that don't? It feels like most nontrivial crates would often need some unsafe. But a system like this might create a scenario where crates offload some of their unsafe code into separate crates so they need updating less frequently (Much like the blah-sys versus blah crates).

> It feels like most nontrivial crates would often need some unsafe

As a frequent contributor to a number of crates, this isn‘t really true. Also, most popular crates actively deny use of unsafe.

I suppose this depends on your definition of "nontrivial", but I don't think most would, unless you count the fact that some stuff in std is implemented with unsafe under the hood. The only times I've ever needed to use unsafe Rust code in 5~ years of writing it professionally was for interfacing with a vendor-specific C library, and that was only for the wrapper around it; the rest of the code didn't need to use unsafe.

Yes I'm probably biased towards seeing more unsafe as a deal with a lot of wrapper libs (crates which in turn have -sys crates and so on). Looking at the dependency graph, if I use 10 deps directly and 5 have unsafe then that might be 50% of the direct dependencies, but probably just a small fraction of the total including transitive.

I think that you can delete files from safe code, but safe as it won't crash or deadlock (but may panic or trigger bugs on unsafe code).

It'd be good to track capabilities needed by libraries, so similarly to unsafe code, risky portions needing careful review are constrained and highlighted in some way.

Reply on news.ycombinator.com