I really liked the old German university concept, the one before we just took over Bachelor/Master.
Throughout my CS studies, I was just collecting "tickets" (very hard to translate the actual word, "Schein"), which basically just attested that you have passed a course. They (often) had a grade on it, but it did not matter. Instead, once in the middle ("pre-diploma") and once at the very end of your time at university, you'd have oral exams. And those determined your grade. To attend them, you needed the right combination of "tickets".
The glaring downside of this system is that if you had a bad time in those few months of your very final exams, you could screw up your entire grade.
The upside of it, is that I was free (and encouraged) to pursue whatever I wanted, without each course risking to have an effect on my "GPA". I had way more tickets than I needed in the end, and still time and energy to pursue whatever else I wanted (playing with microcontrollers etc.).
I had a couple of classes in USA uni that worked quite similarly. The professor said we can take the quizzes if we want, and if we didn't then the later quizzes would constitute more of your grade. The ultimate play was to only take the final quiz.
> The ultimate play was to only take the final quiz.
This is how a lot of British undergrad courses ('modules') work. One giant exam at the very end determining everything; no quizzes, no problem sheets, no midterms.
Going for the pipe spray is a kinda weird technique, and I'm honestly surprised that it worked. Usually just the fact that you are able to spray over the allocation at all isn't enough, and you also have to worry about your sprayed data containing additional pointers or things that also have to be valid.
I probably would have gone for turning the UaF into an type confusion style attack: if you spray more sockets you'll end up with two files, the original and the new one, that have aliased sk members, but the vsock code will incorrectly cast the new one to a `vsock_sock`. From there you can probably find some other socket type that puts controllable data over some field that vsock treats as a pointer or vice versa, and use it as both a kaslr leak and data-only r/w primitive.
> I probably would have gone for turning the UaF into an type confusion style attack
I'm aware that Linux is nearly 40 years old at this point, and C is even decades older. But it is mind-boggling to me that we're still talking about UAFs and jumping from dangling pointers to get privileged executions in the 21st century.
This is an apples-oranges comparison, unless things have changed drastically since the last time I worked on L4 (about 10 years ago). L4 is very secure and easy to reason about. But that's because it doesn't really do anything. It makes a lot of sense as a platform to build a general purpose OS on, and as a bottom layer for what would otherwise be a unikernel. But you'd run a browser on top of something that itself runs on seL4, not on seL4 itself.
It's becoming more and more common to use non Linux based hypervisors to isolate workloads where security matters. Isolating applications within a given VM is not seen as important and therefore ditching Linux isn't really necessary. Applications can continue to be written against Linux APIs and we can create isolation domains separately. This is no longer just a server concept as even phones and cars are starting to employ this technique. It has high cost to RAM, but as RAM gets cheaper it's not as big of a deal.
The obvious question is why Linux is so widely used in the first place. I don't think "APIs" is enough to explain it. One obvious answer is the incredibly broad hardware support. Any alternative selected for use as the hypervisor is going to be at a serious disadvantage in that regard.
Counterargument: Linux is almost 35 years old (wow, time flies). Rust for Linux is a project started at the moment of biggest rust hype. It's understandable that the Linux maintainers are wary of introducing too much rust dependence, in case, for example, all the rust people leave in 5 years and current/old maintainers are stuck with it forever
There are a lot of entities involved that need to be able to work together. Creating a form fractures things and requires all partners to move to said fork. It's far easier to work upstream even with resistance. Anyone who has maintained a long standing Linux fork understands the costs of trying to rebase thousands of patches. There will never be enough of a migration to make it unnecessary to need to rebase.
> So I set off on a journey that would lower my GPA and occasionally leave me questioning my sanity
Amazing! Sacrificing GPA for projects is always a good time
I really liked the old German university concept, the one before we just took over Bachelor/Master.
Throughout my CS studies, I was just collecting "tickets" (very hard to translate the actual word, "Schein"), which basically just attested that you have passed a course. They (often) had a grade on it, but it did not matter. Instead, once in the middle ("pre-diploma") and once at the very end of your time at university, you'd have oral exams. And those determined your grade. To attend them, you needed the right combination of "tickets".
The glaring downside of this system is that if you had a bad time in those few months of your very final exams, you could screw up your entire grade.
The upside of it, is that I was free (and encouraged) to pursue whatever I wanted, without each course risking to have an effect on my "GPA". I had way more tickets than I needed in the end, and still time and energy to pursue whatever else I wanted (playing with microcontrollers etc.).
I had a couple of classes in USA uni that worked quite similarly. The professor said we can take the quizzes if we want, and if we didn't then the later quizzes would constitute more of your grade. The ultimate play was to only take the final quiz.
> The ultimate play was to only take the final quiz.
This is how a lot of British undergrad courses ('modules') work. One giant exam at the very end determining everything; no quizzes, no problem sheets, no midterms.
Modules? We just had six massive exams at the end of three years!
Chicago used to be that way in the long ago times.
Would not be a surprise if AI brought this back.
As a teacher once told me.
"Never let school limit your education"
For those wondering this is a common paraphrase of Grant Allen and Mark Twain. Here we say "Never let school get in the way of a good education."
I learned a ton while at my university. Much of it was outside of my classwork.
Going for the pipe spray is a kinda weird technique, and I'm honestly surprised that it worked. Usually just the fact that you are able to spray over the allocation at all isn't enough, and you also have to worry about your sprayed data containing additional pointers or things that also have to be valid.
I probably would have gone for turning the UaF into an type confusion style attack: if you spray more sockets you'll end up with two files, the original and the new one, that have aliased sk members, but the vsock code will incorrectly cast the new one to a `vsock_sock`. From there you can probably find some other socket type that puts controllable data over some field that vsock treats as a pointer or vice versa, and use it as both a kaslr leak and data-only r/w primitive.
> I probably would have gone for turning the UaF into an type confusion style attack
I'm aware that Linux is nearly 40 years old at this point, and C is even decades older. But it is mind-boggling to me that we're still talking about UAFs and jumping from dangling pointers to get privileged executions in the 21st century.
(rewrite it in Rust)
"We’ve Got a Panic!"
Looks like we've got an encoding issue too.
The server is responding with
i.e. no charset field.The document itself also lacks a declared character set.
I'm confused. The page has a HTML5 doctype, and https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/... says that UTF-8 is the only valid encoding for HTML5 documents, yet Firefox interprets the page as Windows-1252 or such until I "Repair Text Encoding". https://webhint.io/docs/user-guide/hints/hint-meta-charset-u... says you're supposed to include a <meta charset="utf-8"> or optionally Content-Type header.
If you don't have a charset set, then you'll get the fallback for IE compatibility.
You should pretty much always use one.
I thought this was a joke at corrupting the data intentionally
I kind of want to trademark †so that ’ is not just mojibake.
Not sure Musk would let you trademark his kids name. /s
Good write-up. I liked your RSA tutorial too: https://hoefler.dev/content/RSA.pdf
The Linux Kernel has millions of LoCs. There'll always be bugs.
It's about time to look at a sane design, such as seL4[0].
https://sel4.systems/About/seL4-whitepaper.pdf
This is an apples-oranges comparison, unless things have changed drastically since the last time I worked on L4 (about 10 years ago). L4 is very secure and easy to reason about. But that's because it doesn't really do anything. It makes a lot of sense as a platform to build a general purpose OS on, and as a bottom layer for what would otherwise be a unikernel. But you'd run a browser on top of something that itself runs on seL4, not on seL4 itself.
It's becoming more and more common to use non Linux based hypervisors to isolate workloads where security matters. Isolating applications within a given VM is not seen as important and therefore ditching Linux isn't really necessary. Applications can continue to be written against Linux APIs and we can create isolation domains separately. This is no longer just a server concept as even phones and cars are starting to employ this technique. It has high cost to RAM, but as RAM gets cheaper it's not as big of a deal.
The obvious question is why Linux is so widely used in the first place. I don't think "APIs" is enough to explain it. One obvious answer is the incredibly broad hardware support. Any alternative selected for use as the hypervisor is going to be at a serious disadvantage in that regard.
don’t mind if you do guv.
Yay Rop Chains!
[stub for offtopicness]
Cool writeup, and you have exceptional taste in fonts.
I can't read the dark blue links on the black background
Engage reading mode and relax.
Victim blaming.
For the love of god please change the blue on black text to something more readable
The dark blue on black reads absolutely terribly
Try the Reader View feature of Firefox.
yet another "use-after-free" sploit
Rust for Linux, wen?
It's a damn shame the current maintainers are so hostile to its adoption that many of the original rust 4 linux folks have left the project.
Counterargument: Linux is almost 35 years old (wow, time flies). Rust for Linux is a project started at the moment of biggest rust hype. It's understandable that the Linux maintainers are wary of introducing too much rust dependence, in case, for example, all the rust people leave in 5 years and current/old maintainers are stuck with it forever
Did they start their own project ? Linux is free, just fork it.
There are a lot of entities involved that need to be able to work together. Creating a form fractures things and requires all partners to move to said fork. It's far easier to work upstream even with resistance. Anyone who has maintained a long standing Linux fork understands the costs of trying to rebase thousands of patches. There will never be enough of a migration to make it unnecessary to need to rebase.
The 'just' doesn't belong in front of 'fork'.
Rust, the new "I use Arch, BTW"