ryao

55 ms·

751.
by ryao 2y ago
What's odd about this argument is that such bugs would be at risk of reintroduction in any other piece of software. They can be reintroduced into seL4 too. Just have an amendment to the specification adding a new feature say th
752.
by ryao 2y ago
How does “This issue was present in the specification against which seL4 was verified” not imply yes to that question?
753.
by ryao 2y ago
Thanks for the clarification.
754.
by ryao 2y ago
OSF/1 1.3 switched to Mach 3.0.
755.
by ryao 2y ago
That resulted in a memory corruption flaw in the C code. If you build a bridge to a specification and the bridge collapses, does saying that the specification was wrong in any way lessen the reality that the bridge failed?
756.
by ryao 2y ago
This issue appears to have affected all architectures. This issue was present in the specification against which seL4 was verified. You can say that there are no bugs by virtue of it following the specification, but if the specification was
757.
by ryao 2y ago
OSF/1 is the closest that microkernels ever came to being used in general purpose operating systems: https://en.wikipedia.org/wiki/OSF/1 The only still living variant is AIX. Some of the code is in the XNU ke
758.
by ryao 2y ago
NT and XNU never had microkernel origins - Cutler explicitly refuted this at a conference in the early 1990s Interestingly, the Tanenbaum–Torvalds debate had Tanenbaum claim otherwise at the very start: The alternative is a mic
759.
by ryao 2y ago
Being "formally proven" to be free of various flaws did not make seL4 immune to memory corruption flaws. Despite the formal proof, a memory corruption flaw was found a few years ago. The PRs for the commits fixing it and amending
760.
by ryao 2y ago
Nice use of Latin. mihi placet.
761.
by ryao 2y ago
I feel like the two of you are talking past each other as the other poster is talking about time sharing systems like UNIX while you are pointing at embedded applications that are OS optional and if there is any semblance of an OS, it is re
762.
by ryao 2y ago
seL4 having a proof of correctness does not mean all microkernels do. In fact, seL4 is the only microkernel that has a proof of correctness. If you build on top of it in the microkernel way, you quickly find that it is not performant. That
763.
by ryao 2y ago
Perhaps scp -p or sshfs would have worked. This is just a guess. I am not certain.
764.
by ryao 2y ago
Of all of the stories I have read here, this is the first to make me laugh. Congratulations. :)
765.
by ryao 2y ago
I have setup ssh remote forwards to a jump host in the past to allow remote access through a firewall. daemontools executes scripts exec’ing ssh. ExitOnForwardFailure and ServerAliveInterval are set client side with ClientAliveInterval and
766.
by ryao 2y ago
Presumably, the read shell builtin can be used to read files in /proc. As per the original article, you can get a static version over the network using only bash builtins and overwrite a file with execute permission to be able to execu
767.
by ryao 2y ago
> ASLR is not security through obscurity. I used to think this, but hearing about the AnC attack changed my mind. I have never heard of anyone claiming to mitigate it.
768.
by ryao 2y ago
The Solaris VFS is flexible enough for a filesystem to support this, but any filesystem that does violates POSIX according to a comment in ZFS. A check of the illumos UFS driver source code reveals that it violates POSIX by permitting root
769.
by ryao 2y ago
It is more nuanced than that. First, the Solaris 11.4 documentation says that this is not allowed: https://docs.oracle.com/cd/E88353_01/html/E72487/link-8.html The illumos man page is less clear: https:
770.
by ryao 2y ago
It is not the same thing, but recently, my pfsense router started acting weird where dns stopped working. I was bust so I rebooted it and it failed to boot. I ended up bringing a monitor and keyboard to see what went wrong and it turned out
771.
by ryao 2y ago
Gentoo used to include a static busybox binary for recovery purposes, but it was removed from the system set years ago. Now you are expected to use the initramfs for recovery and can install bust box yourself if you are concerned. In fairne
772.
by ryao 2y ago
Do you mean moving it? You cannot make a hard link for a directory. That is disallowed on Unix to prevent the creation of orphaned subtrees (i.e. ln a directory into itself and then rmdir the original link).
773.
by ryao 2y ago
The technical term is unlinked. The files in use by running processes are still anonymous files in the filesystem. They will not be garbage collected until the last program that mmap’ed them is gone. If you could find the inode number from
774.
by ryao 2y ago
I do not think things like the time command need to be compiled with such things. It is pointless, but your suggestion here is to do it anyway. Why bother? Assertions in release builds are a bad idea since they can be fairly expensive. It i
775.
by ryao 2y ago
If you can look up the base address via AnC, is considering it to be a protected key material really correct?
776.
by ryao 2y ago
You are not wrong, but how big of a caveat it is varies. On a client system, it is an incredibly low bar given client side scripting in web browsers (and end users’ tendency to execute random binaries they find on the internet). On a server
777.
by ryao 2y ago
With attacks such as AnC, your logic fails. They can figure out the locations and get plenty of stable gadgets. Any shuffling of a deck of cards by Alice is pointless if Bob can inspect the deck after she shuffles them. It makes ASLR not ve
778.
by ryao 2y ago
Except I do know what security by obscurity is and you are out of date on the subject. When you have attacks that make ASLR useless, then it is security by obscurity. Your thinking would have been correct 10 years ago. It is no longer corre
779.
by ryao 2y ago
The kernel address space is the same regardless of how many fork() calls have been done. I would assume the exploitation path for a worst case scenario would be involve chaining exploits to do: AnC on userspace, JavaScript engine injection
780.
by ryao 2y ago
I use non-standard SSH ports too. It does not improve theoretical security, but it does improve quality of life from generating smaller logs.

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