Best part is the fix:
https://github.com/sudo-project/sudo/commit/b5d2010b6514ff45...
Time to delete sudo.
https://github.com/sudo-project/sudo/commit/b5d2010b6514ff45...
Time to delete sudo.
We should have standardized a C API to safely read/write buffers from files, networks, etc. decades ago. But here we are in 2020 manually moving pointers around - and what a surprise that we're finding "whoops, another off-by-one error, you know how it goes."
No one should be writing new code to read/write bytes. This should be settled. It's like a carpenter building their own nail gun each time they want to build a house.
AFAICT, the only real changes are in (new) line 411, resetting the cp variable after the loop, and line 416, ignoring write errors. The former is probably the relevant one.
This is a small enough diff that I wouldn't complain if given this to review - but I probably also would've reverted the style changes (and would give myself at least 50/50 odds of splitting the changelist in two)
Perhaps I've just been too broken by 1000+ LOC diffs that intersperse multiple behavior changes and style and refactoring and ...
The prefix/postfix change does something to the reader. It's a distraction trying to figure out if that change was intended, whether the author knows it has no effect, or whether I'm wrong about the change having no effect.
I appreciate the author doing the hard work of fixing this, especially with the code in full view of the public, but if I were an official reviewer I'd ask to get all the unnecessary changes removed.
https://github.com/sudo-project/sudo is just a mirror.
Maybe I'm missing something, but wasn't that a pointless change? The value of the expression was unused, so post- and pre- are equivalent.
When I was a pentester, out of more than 50 projects I was on, I always found at least a medium-severity bug (a bug which could allow an attacker to pwn the app using nothing but a web browser). Guess how many of those codebases were written in C? Zero.
The smugness is endemic to people outside of security. I was smug too. There are comments I wrote that I cringe at, looking back. Pentesting changes your perspective on things.
C isn't going away. Yes, let's make it safer (by pentesting). No, it's not a mortal sin to write C. I'll find ways to exploit your webapp regardless of the language.
So, based on those two comments, you have zero data (anecdotal or other) comparing the rate of bugs in C programs versus other languages since you didn't test any C programs.
Code security is not about eliminating bugs but about lowering the rate they show up at since things always get through and money/time is finite. Pen testing doesn't catch everything and many projects that have been tested still yield bugs. There's also a limit to how much money can be spent on testing so using it find (and document, review, etc.) low hanging bugs due to using C means you're more likely to miss a deeper bug.
Or in other words, spending the same effort to pen test a safe language will leave fewer bugs left over than spending it to pen test an unsafe language. So using an unsafe language is still worse.
"An API should be easy to use correctly and hard to use incorrectly"
The dumbest link in the chain is always the guy writing the code, not the programming language, and not the machine executing it. So things should be designed in a way that makes it as hard as possible for programmers to make errors.
e: video is here for those who are interested https://www.youtube.com/watch?v=5tg1ONG18H8
Think about how often you blindly inserted a USB A or B (mini-B, micro-B) plug the wrong way first and had to try again. Why is the wrong way even possible? USB C's plug fixes this.
A huge improvement to railway safety was the invention of Mechanical Interlocking. It was made essentially impossible to set signals in some inherently unsafe ways. When you tried to give a Clear signal to the Express, through a junction a late running Coal Train is already crossing, the huge metal lever you're trying to move to do that won't budge because all your controls are connected via elaborate mechanical interlocking to prevent this mistake. The signal remains at Danger, the Express stops, tragedy is averted.
To be honest this isn't really an issue once you notice that the logo side of the USB connector indicates up. I suspect this is mostly an issue because USB connectors have only a tiny self-alignment range (<1 mm), which leads to the "USB exists in a 4D state" meme.
Don't write code in unsafe languages unless you have to (almost never for new code). Period. You will have some problems either way, but you will have fewer problems in a memory safe language.
Pen testing is not even remotely a good mitigation to depend on against the dangers of a language like C. Its fine to do for defense in depth and to find problems not related to memory safety, but it's no substitute for making a more sensible language choice.
A big part of why people make a big deal of C is that there are lots of code bases that have been under a lot of scrutiny from security minded code reviewers and pentesters and still keep on yielding more vulnerabilities. Ie it's hard to make C safe even when you really try and are a good programmer.
In contrast IME most pentesters in the biz work on code bases that have seen much less scrutiny and are often in-house and/or "enterprise" apps whose code was written by people who are probably more domain experts than generally good programmers or security-aware developers...
Perhaps you were a good pentester. More likely the code you attacked was rubbish.
I worked on a relatively important Internet-facing web application for about a decade, it was pen tested by a variety of outfits both when it was owned by a small start-up and when it was owned by a huge corporation.
Good design meant that we never saw any pen tester come anywhere close to "pwn the app" in either its public UI or the APIs which were (by my insistence) publicly accessible rather than wasting our time chasing endless "please change the allowed IP ranges" requests through layers of bureaucracy.
My experience was pen testers would bang on the predictable places, try obvious things, maybe trigger some alarms which I then had to pause - and get nowhere. We'd get back a report that said things like if I put in this nonsense email address I get a different error message than this other nonsense email address. OK, that's nice we'll put it on the backlog, did you find any actual security problems? No.
I'd say that using a memory safe language (Java) helped make that happen, IMNSHO as a very good C programmer for whom writing it in Java was not my first choice (nor was C).
In comparison, so much modern javascript is written by junior developers - often without a lot of oversight. Junior developers can't "see" security vulnerabilities yet because they haven't learned to look for them. So I'm not surprised there's lots of critical vulnerabilities in modern software. Many coding bootcamps don't bother to teach any security engineering or best practices, and doing consulting work I've (often by chance) caught a disastrous amount of awful code people have tried to push to production simply because they didn't know any better. A lot of it is really simple stuff - guessable database IDs used as session tokens. JSON objects passed from the browser directly into mongodb. Authentication checks accidentally missing from certain admin dashboard APIs. Passwords and credit card information stored in plaintext, handrolled crypto, and so on.
Given the choice between C code and Rust code written by someone who's been programming for 30 years I expect the rust code would be safer. But if I'm asked to choose between C code written by an experienced engineer and javascript code written by a junior engineer, it wouldn't surprise me if it turned out that the C code was on average still more secure.
(Not that 20 years of experience makes you a decent secure C programmer, but that's a different argument)
What experiences have given you that opinion?
I don't remember too many specifics (it was a while ago) other than being brought onboard and having to introduce the tech lead to the "static" keyword.
Is it so wrong to recommend a solution that will kill a good chunk of the problems right at the door?
And FYI, you are being pretty smug here as well. The fact that people criticised unrelated parts of the PR in addition to the relevant parts shouldn't give you a free license to dismiss the bigger criticism.
Perhaps it's meant to match a style guide that recommends preferring postfix operators? Or perhaps it's editing shrapnel from an earlier version of the changelist, that maybe used the result of that statement?
The amount of anti-education authoritarian fearmongering in these discussions is disturbing. Then again, given how much everything seems to be rapidly moving in the direction of dystopian corporatocracy, perhaps that's not so surprising.
There's already a few comments about how "safer" languages don't really solve anything. They just push the problems up higher in the stack of abstractions... and when that time comes, what are the chances the "security" fearmongerers will just start blaming something else? It's fundamentally a problem of competence, and doing everything you can to make the world a prison in pursuit of that "perfect security" is really not a good idea. There's no replacement for intelligence.
Also let's not forget that C exploits go back to the 80's, when most of us where doing full application in Assembly.
Supposedly we knew our pointers pretty well.
I'm not sure this statement adds anything to your argument. "Exploits go back as far as the language was in common use" doesn't really mean anything.
I'm sure Ada has had exploits, especially around its early lifetime. But its a language that's supposed to be safe.
Yes. Exactly. Exploits having existed for a long time isn't interesting or relevant.
I offered no defence of C. Just that the point wasn't relevant to the argument, one way or the other.
>People who understand these essential basics, e.g. by starting with Asm, are going to be far less likely to make these sorts of mistakes and write less buggy code in general.
Userbinator's post continues and seems to paint the ecosystem as getting worse over time, as if it were much better in this area in the past. Pjmlp's point was that even the original C users who came from assembly, who were presumably more familiar with the essential basics of assembly and memory management, still pumped out vulnerable code as we see today. It doesn't seem like having a userbase made up of experienced assembly programmers is enough for C to be predictably safe.
Some pre-89 code won't even compile today without putting in considerable effort.
Morris worm was the first widely know C exploit, which still gives us about 30 years of exploits to look into.
Regarding how many exploits other languages have, for starters not memory corruption due to out of bounds access, integer overflow or implicit casts, as Algol derived system languages, since 1961 (8 years before C was even an idea), had checks for those kind of errors.
C only made it to fame, because original UNIX could not be sold and its source code tapes went from university to university.
Had it not been so, probably we would be using Bliss, PL/I, Mesa, PL/S, and not having arguments how good one needs to be to write code that doesn't allow for memory corruption errors.
Exploits being consistently discovered over a long time is, and does help your argument.
Here's one for how safe that was: alloca could not guarantee the pointer it handed you is either valid, or the size you requested.
POSIX.1 only came along in '88 (with our first definition of stdlib). Whilst IO had mostly stabilised by that point, there were still plenty of platforms that didn't use the Bells header (stdio.h).
Files, signals, floating point behaviour, process creation - none of that was standardised yet.
Most of what was defined by POSIX already existed on common platforms, like SunOS, before it was formally standardized. SunOS 4.0 even had mmap in early 1988! (See https://archive.org/stream/bitsavers_sunsunos4.erenceManual1... )
Understanding these concepts is not the problem. The problem is that even people who understand them very well regularly make mistakes when programming with them, and in C these mistakes have disastrous consequences.
> There's already a few comments about how "safer" languages don't really solve anything. They just push the problems up higher in the stack of abstractions...
The problems that exist higher in the stack of abstractions are present in C programs too. C just creates a lot of additional ways to subvert your program.
I used to have the attitude around vulnerable code of "The problem would be solved if everyone else was just better [like me]". I was desperately trying to prove myself. I'm good at finding and solving tricky bugs, including exploitable memory corruption issues. It felt nice having a thing that I was clearly superior to others in. I loved languages like C where I had a great knowledge of the footguns and I could save the day in. But then I got a good job, I no longer felt undervalued and needing to prove myself at all costs, and my attitude shifted.
I can't write the whole codebase myself or double-check everyone's work. This didn't really matter if I was just concerned with making myself look good, but if the thing I cared about was the product itself and stopping bugs (especially exploitable ones) from getting in to begin with, then it wasn't enough to drop in occasionally to save the day and chide others for not knowing enough about the specific footguns lying around. If there were a bunch of tools that were misused 2/3 of the times they were used in the company, then I could accomplish far more by finding and advocating for safer replacement tools than I could accomplish if I tried to double-check every time the old tool was used and endlessly reminded people that the flesh-magnetic hammer will seek out your thumb unless you know to use some specific swinging strategy.
>There's already a few comments about how "safer" languages don't really solve anything. They just push the problems up higher in the stack of abstractions
A program written in any general purpose language can have high-level bugs like forgetting to check the user's password when they sign in, but only languages with manual memory management make it easy to also have an exploitable memory corruption bug when handling the memory containing the user's password. Solving some kinds of issues is valuable because that can help reduce the count, likelihood, and severity of issues that do happen.
>The amount of anti-education authoritarian fearmongering in these discussions is disturbing. Then again, given how much everything seems to be rapidly moving in the direction of dystopian corporatocracy, perhaps that's not so surprising.
>... and when that time comes, what are the chances the "security" fearmongerers will just start blaming something else?
What possible ulterior motive do you think people advocating safer languages have? I really can't tell if this is parody. Do you think Mozilla made Rust as part of some bigger political narrative, rather than to just make it easier for them to write bug-free code?