src VS OpenVi

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...

The behavior of the traditional vi is much different than vim and other clones. Nvi was a actually a re-implementation of the traditional vi for 4BSD (to be clean of AT&T code) and thus was originally intended to be bug-for-bug compatible, but breaking away where the original vi behavior was nonsensical or terrible.

For vim, `set compatible` or `set cp` is close, but still not traditional vi by any means.

A multibyte variant of the tradition vi is maintained - https://github.com/n-t-roff/heirloom-ex-vi/.

Nvi (now on version 1.8x) is also maintained - https://repo.or.cz/nvi.git

Nvi2 is yet another fork of Nvi, https://github.com/lichray/nvi2

Despite the very similar names, all of these editors have a variety of different features, and are structured very differently.

Nvi has a concept of a front-end and a back-end (which uses the BDB database). OpenVi uses the OpenBSD version of Berkeley DB which derives from 1.85. Nvi (1.8x) provides a minimal version of code also derived from that release intended from use with Nvi, and (IIRC) also provides support for using Db3/4/5. Similar situation for Nvi2.

Nvi 1.8 has been structured where a third library layer has been added, which doesn't exist in OpenBSD's vi or OpenVi. There is scripting support (Tcl, Perl, etc.) and GUI code in the other various forks ... all of these support various different options as well.

I should probably make a matrix of these, but you can get an idea by looking at the settable options implemented in each of the variants (as they historically include a comment to document from where the option originated):

OpenVi: https://github.com/johnsonjh/OpenVi/blob/22c2a7022e31d91e09e...

OpenBSD vi: https://github.com/openbsd/src/blob/master/usr.bin/vi/common...

Nvi2: https://github.com/lichray/nvi2/blob/5fcdc13656500a8c5b4c073...

Nvi1: https://repo.or.cz/nvi.git/blob/HEAD:/common/options.c#l52

OpenVi: Portable OpenBSD vi for Unix systems\ (22 comments)