Comment by josephg | Hacker News Reader

Comment by josephg | Hacker News Reader

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> Suggesting a tabula rasa rewrite of NSS would more likely be met with genuine concern for your mental well-being, than by incredulity or skepticism.

In my experience, porting code more or less directly from one language to another is faster and easier than people assume. Its certainly way faster than I assumed. I hand ported chipmunk2d to javascript a few years ago. Its ~30k LOC and it took me about a month to get my JS port working correctly & cleaned up. I spend up throughout the process. By the end I had a bunch of little regexes and things which took care of most of the grunt work.

If we assume that rate (about 1kloc / person-day) then porting boringssl (at 356kloc[1]) to rust would take about one man-year (though maybe much less). This is probably well worth doing. If we removed one heartbleed-style bug from the source code on net as a result, it would be a massive boon.

(But it would probably be much more expensive than that because the new code would need to be re-audited.)

[1] https://www.openhub.net/p/boringssl/analyses/latest/language...

> In my experience, porting code more or less directly from one language to another is faster and easier than people assume.

That's often true right up to the point where you have to be keenly aware of and exceptionally careful with details such as underlying memory management functionality or how comparisons are performed. With this in mind, cryptographic code is likely a pathological case for porting. It would be very easy to accidentally introduce an exploitable bug by missing, for example, that something intentionally reads from uninitialized memory.

On top of the re-audit being expensive.

> for example, that something intentionally reads from uninitialized memory.

Sounds terrible. This should never happen in any program, so any behavior relying on it is already broken.

I'm way more concerned by memory safety issues than cryptographic issues. Frankly, history has shown that cryptographic bugs are far easier to shake out and manage than memory safety bugs.

> Frankly, history has shown that cryptographic bugs are far easier to shake out and manage than memory safety bugs.

and yet, we had the debian/ubuntu openssl bug of 2008... due to someone not wanting to intentionally read from uninitialized memory. Really, it kind of proved the opposite. Valgrind and other tools can tell you about memory safety bugs. Understanding that the fix would result in a crypto bug was harder.

OpenSSL's use of uninitialized memory to seed entropy was always a terrible idea. The PRNG was fundamentally flawed to begin with.

> Really, it kind of proved the opposite.

Not really. Exploited bugs in cryptographic protocols are extremely rare. Exploited memory safety bugs are extremely common.

> Valgrind and other tools can tell you about memory safety bugs.

Not really.

> Understanding that the fix would result in a crypto bug was harder.

Like I said, OpenSSL's PRNG was brutally flawed already and could have been broken on a ton of machines already without anyone knowing it. A compiler update, an OS update, or just unluckiness could have just as easily broken the PRNG.

Building memory unsafety into the prng was the issue.

Memory safety issues are exploited orders of magnitude more often than crypto bugs.

edit: Also, memory safety bugs typically have higher impact than crypto bugs. An attacker who can read arbitrary memory of a service doesn't need a crypto bug, they can just extract the private key, or take over the system.

Crypto bugs are bad. Memory safety bugs are way, way worse.

Genuinely curious what the use case(s) of reading from uninitialized are. Performance?

It was used as a source of randomness. Someone blindly fixing a "bug" as reported by a linter famously resulted in a major vulnerability in Debian: https://www.debian.org/security/2008/dsa-1571

This is incorrect.

If they had simply removed the offending line (or, indeed, set a preprocessor flag that was provided explicitly for that purpose) it would have been fine. The problem was that they also removed a similar looking line that was the path providing actual randomness.

If a programs reads from uninitialised memory, I hope for its sake that it does not do it in C/C++. Setting aside that uninitialised memory is a hopelessly broken RNG seed, or the fact that the OS might zero out the pages it gives you before you can read your "uninitialised" zeroes…

Reading uninitialised memory in C/C++ is Undefined Behaviour, plain and simple. That means Nasal Demons, up to and including arbitrary code execution vulnerabilities if you're unlucky enough.

> In my experience, porting code more or less directly from one language to another is faster and easier than people assume

Converting code to Rust while keeping the logic one-to-one wouldn't work. Rust isn't ensuring memory safety by just adding some runtime checks where C/C++ aren't. It (the borrow checker) relies on static analysis that effectively tells you that the way you wrote the code is unsound and needs to be redesigned.

Sounds like a feature of the porting process. Not a bug. And I’d like to think that BoringSSL would be designed well enough internally to make that less of an issue.

I agree that this might slow down the process of porting the code though. I wonder how much by?

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