[coderjames]

> In particular, our code to parse .deb, .ar, .tar, and the HTTP signature verification code would strongly benefit from memory safe languages

> Critical infrastructure still written in C - particularly code that parses data from untrusted sources - is technical debt that is only going to get worse over time.

But hasn't all that foundational code been stable and wrung out already over the last 30+ years? The .tar and .ar file formats are both from the 70s; what new benefits will users or developers gain from that thoroughly battle-tested code being thrown out and rewritten in a new language with a whole new set of compatibility issues and bugs?

[julian-klode]

I wish, but I get new security bugs in those components like every year or so, not all are tracked with security updates to be fair, some we say it's your own fault if you use the library to parse untrusted code.

After all the library wasn't designed around safety, we assumed the .debs you pass to it are trusted in some way - because you publish them to your repository or you are about to install them so they have root maintainer scripts anyway.

But as stuff like hosting sites and PPAs came up, we have operators publishing debs for untrusted users, and hence suddenly there was a security boundary of sorts and these bugs became problematic.

Of course memory safety here is only one concern, if you have say one process publishing repos for multiple users, panics can also cause a denial of service, but it's a step forward from potential code execution exploits.

I anticipate the rewrites to be 1 to 1 as close as possible to avoid introducing bugs, but then adding actual unit tests to them.

[RustSupremacist]

"The best laid plans of mice and men often go awry."

[jcranmer]

> But hasn't all that foundational code been stable and wrung out already over the last 30+ years?

Not necessarily. The "HTTP signature verification code" sounds like it's invoking cryptography, and the sense I've had from watching the people who maintain cryptographic libraries is that the "foundational code" is the sort of stuff you should run away screaming from. In general, it seems to me to be the cryptography folks who have beat the drum hardest for moving to Rust.

As for other kind of parsing code, the various archive file formats aren't exactly evolving, so there's little reason to update them. On the other hand, this is exactly the kind of space where there's critical infrastructure that has probably had very little investment in adversarial testing either in the past or present, and so it's not clear that their age has actually led to security-critical bugs being shaken out. Much as how OpenSSL had a trivially-exploitable, high criticality exploit for two years before anybody noticed.

[julian-klode]

Actual cryptography code, the best path is formally verified implementations of the crypto algorithms; with parsers for wrapper formats like OpenPGP or PKCS#7 implemented in a memory safe language.

You don't want the core cryptography implemented in Rust for Rust's sake when there's a formally verified Assembler version next to it. Formally verified _always_ beats anything else.

[jcranmer]

I should have clarified that I was primarily referring to the stuff dealing with all the wrapper formats (like PKIX certificate verification), not the core cryptographic algorithms themselves.

The core cryptographic algorithms, IMHO, should be written in a dedicated language for writing cryptographic algorithms so that they can get formally-verified constant-time assembly out of it without having to complain to us compiler writers that we keep figuring out how to deobfuscate their branches.

[oofbey]

Sure. But assembly implementations by definition are not portable. And I don’t know what it takes to write a formally verified library line this, but I bet it’s very expensive.

In contrast, a rust implementation can be compiled into many architectures easily, and use intrinsically safer than a C version.

Plus cryptography and PKI is constantly evolving. So it can’t benefit from the decades old trusted implementations.

[kelnos]

> Formally verified _always_ beats anything else.

Formally verified in an obscure language where it's difficult to find maintainers does not beat something written in a more "popular" language, even if it hasn't been formally verified (yet?).

And these days I would (unfortunately) consider assembly as an "obscure language".

(At any rate, I assume Rust versions of cryptographic primitives will still have some inline assembly to optimize for different platforms, or, at the very least, make use of compile intrinsics, which are safer than assembly, but still not fully safe.)

[steveklabnik]

With crypto, you really want to just write the assembly, due to timing issues that higher level languages simply cannot guarantee.

[julian-klode]

It's insanely complex, particularly you want _verified_ crypto. Last year (or two years ago?) I had to fix a tiny typo in OpenSSL's ARM assembly for example, it was breaking APT and Postgres left and right, but only got triggered on AWS :D

[AlotOfReading]

You don't want to write the whole thing in assembly, just the parts that need to be constant time. Even those are better written as called subroutines called from the main implementation.

Take BLAKE3 as an example. There's asm for the critical bits, but the structural parts that are going to be read most often are written in rust like the reference impl.

[steveklabnik]

Yes, for sure.

[tialaramex]

I would like a special purpose language to exist precisely for writing crytographic code where you always want the constant time algorithm. In this niche language "We found a 20% speed-up for Blemvich-Smith, oops, it actually isn't constant time on the Arrow Lake micro-code version 18 through 46" wouldn't even get into a nightly let alone be released for use.

It seems that for reasons I don't understand this idea isn't popular and people really like hand rolling assembly.

[AlotOfReading]

There's been plenty, like RobustIsoCrypt or FaCT:

https://github.com/PLSysSec/FaCT

They struggle to guarantee constant time for subroutines within a non-constant time application, which is how most people want to use cryptography.

[jcranmer]

I do think this is pretty much the one use case for a true "portable assembler", where it basically is assembly except the compiler will do the register allocation and instruction selection for you (so you don't have to deal with, e.g., the case that add32 y, x, 0xabcdef isn't an encodable instruction because the immediate is too large).

[sn9]

You can't avoid those with NASA Power of 10 sorts of restrictions?

[bgwalter]

If you mean GnuPG, that is what Snowden used. It could be better than new software that may have new bugs. Memory safety is a very small part of cryptographic safety.

(New cryptographic software can also be developed by all sorts of people. In this case I'm not familiar, but we do know that GnuPG worked for the highest profile case imaginable.)

[pclmulqdq]

GPG works great if you use it to encrypt and decrypt emails manually as the authors intended. The PGP/GPG algorithms were never intended for use in APIs or web interfaces.

Ironically, it was the urge not to roll your own cryptography that got people caught in GPG-related security vulnerabilities.

[ok123456]

There are none. This is a canonical employee trying to force Ubuntu's decisions (rust coretools) on the wider Debian community.

Additionally, the fact that this comes across as so abrasive and off-putting is on brand for online Rust evangelicalism.

[Denvercoder9]

> But hasn't all that foundational code been stable and wrung out already over the last 30+ years?

No: a little less than 5 years ago there was CVE-2020-27350, a memory safety bug in the tar/ar implementations.

[Arrowmaster]

But just this year there was CVE-2025-62518 in tokio-tar.

[hiccuphippo]

Every software is stable and wrung out until someone finds an exploit.

[blub]

Recently the rust coreutils had a bug and this essentially disabled auto-updates on Ubuntu. :)

Seeing this tone-deaf message from an Ubuntu employee would be funny if I didn’t actually use Ubuntu. Looks like I have to correct that…

[julian-klode]

Isn't it also funny that all of these things are done by the same person?

In all seriousness though, let me assure you that I plan to take a very considerate approach to Rust in APT. A significant benefit of doing Rust in APT rather than rewriting APT from scratch in Rust means that we can avoid redoing all our past mistakes because we can look at our own code and translate it directly.

[rpcope1]

Honestly having seen trainwreck after trainwreck after trainwreck come out of Canonical for the last decade, I'm sure I'm not the only one that has strong doubts about anyone associated being able to "avoid redoing past mistakes" or to make things not suck.

[RustSupremacist]

You have never been skilled at being considerate:

https://github.com/keepassxreboot/keepassxc/issues/10725#iss...

[chris_wot]

Christ that was handled badly.

[blub]

Seems reasonable. I wish you would have written that in your original message. Good luck…