src VS freebsd-src

The OpenBSD project released 7.4 of their OS on 16 Oct 2023 as their 55th release 💫

Well since https://www.openbsd.org/ still says

> Only two remote holes in the default install, in a heck of a long time!

I'm assuming not, but I could always be mistaken.

> building a cat from scratch

> That would be an interesting project.

Here is the source code of the OpenBSD implementation of cat:

> https://github.com/openbsd/src/blob/master/bin/cat/cat.c

and here of the GNU coreutils implementation:

> https://github.com/coreutils/coreutils/blob/master/src/cat.c

Thus: I don't think building a cat from scratch or creating a tutorial about that topic is particularly hard (even though the HN audience would likely be interested in it). :-)

> I don't know how they define `MAX`, but I'm guessing it's a typical "a>b?a:b"

Indeed: https://github.com/openbsd/src/blob/master/sys/sys/param.h#L...

> Then `SYS_kbind` seems to be a signed int.

It's an untyped #define: https://github.com/openbsd/src/blob/master/sys/sys/syscall.h...

I believe your whole analysis is correct, that running an elf file with an openbsd.syscalls entry with .sysno > INT_MAX will allow an out-of-bounds write.

I can reproduce it. And this is the commit that causes the issue: https://github.com/openbsd/src/commit/d21788ce70be80e9c4ed0c52c149e01147c4a823

This doesn’t really change your conclusion, but I think that’s the wrong file. This is the real doas afaict: https://github.com/openbsd/src/blob/master/usr.bin/doas/doas...

Still just a tidy 1072 lines in that folder though.

I spent 5 minutes staring at your file trying to understand how on earth it does the things in the man page, but of course it doesn’t.

OpenBSD developers are making serious effort to kill off indirect syscalls, the base system is completely clean, take a look at the work Andrew Fresh did to adapt Perl. He write a complete syscall "dispatcher" or emulator for the Perl syscall function so that it calls the libc stubs.

https://github.com/openbsd/src/commit/312e26c80be876012ae979...

The ports tree is also being cleansed of syscall(2) usage, until they're all gone.

msyscall, pinsyscall, recent mandatory IBT/BTI, xonly. OpenBSD is making waves, but people aren't really seeing them yet.

Actually, I got it wrong, too many vulnerabilities in flight. They did fix it: https://github.com/openbsd/src/commit/375ccafb2eb77de6cf240e...

2023-06-26: https://github.com/freebsd/freebsd-src/commit/ee0aa1ce12b3caea34477a31e9d2111a329e33b9 to main (tagged release/14.0.0).

It's not yet in FreeBSD base so if you want to test it you'll have to use the patch from the PR: https://github.com/freebsd/freebsd-src/pull/881

Lots of great work by many people. But I bet this guy and his optimizations to the vfs and locking has made a significant impact.

https://github.com/freebsd/freebsd-src/commits?author=mjguzi...

and then there were deep concerns about the stability of same, so vfs.zfs.bclone_enabled = 0 was left in-place

https://github.com/freebsd/freebsd-src/commit/068913e4ba3dd9...

Well there are some examples:

https://github.com/freebsd/freebsd-src/tree/main/share/examp...

But yeah that pf.conf could be expanded allot, but there are many source to cobble a conf together. My conf is massive but 99.9% commented out so i have my "template" for nearly everything, from mail to web to blacklistd etc.

The BSD version is sort of very recent, for what it's worth -- FreeBSD imported a not fully functional version in 2017 and has seen more work on it in 2022: https://github.com/freebsd/freebsd-src/commits/main/usr.bin/... , but the default version shipped is still GNU diff3: https://man.freebsd.org/cgi/man.cgi?query=diff3&apropos=0&se... .