From: Steffen Nurpmeso <steffen@sdaoden.eu>
Subject: Re: openat(2) is mostly useless, sadly
To: "Theo de Raadt" <deraadt@openbsd.org>
Cc: "H. Hartzer" <h@hartzer.sh>, tech@openbsd.org
Date: Fri, 30 May 2025 23:03:25 +0200

Theo de Raadt wrote in
 <13341.1748637162@cvs.openbsd.org>:
 |Steffen Nurpmeso <steffen@sdaoden.eu> wrote:
 |> H. Hartzer wrote in
 |>  <DA9P8IWDKRGV.SLD91CZNP0WP@hartzer.sh>:
 |>|Theo de Raadt wrote:
 |>|> instead of requiring a programmer to put a flag on every system call \
 |>|> acting
 |>|> upon the object.  Two operational flags are added, O_BELOW and F_BELOW.
 |>  ...
 |>|I wanted to point out that the language can be confusing of "above",
 |>|"below", etc. Now it may be that this is named as appropriately as it
 |>|can be, but while I was reading my instinct was that "below" meant a
 |>|child directory, rather than a parent. I think there may be some
 |>|confusion over the semantics.
 |>|
 |>|O_BELOW also sounds somewhat like it allows below, but not only below.
 |>|Maybe O_ONLYBELOW? Another possibility might be something like O_CHROOT,
 |>|which is a familiar and similar term, though might add other confusion.
 |>|
 |>|I think that ascend/descend might be somewhat more intuitive terms.
 |>|Perhaps O_DESCEND, or O_ONLYDESCEND.
 |> 
 |> How about "beneath" as Linux landlock uses?
 |
 |How about I use some other flag which already exists, and has different
 |semantics.  Like how about O_EXCL??
 |
 |/sarc
 |
 |You see, O_BENEATH already exists elsewhere, and is not compatible.
 |https://reviews.freebsd.org/D2808

..it was O_RESOLVE_BENEATH.  Do not believe i have this highly
non-portable stuff present, it was only in the back of my mind.

 |We are at the stage where people want to change the names of things,
 |but I don't know of one person who has compiled a kernel with the diffs.

I would not use ENOTTY for F_BELOW on !DIR, maybe ENOTDIR is
better.  Maybe also for vn_open, i do not know.
Testing, sorry.  I have not built OpenBSD from source for about
fourteen years, i think.
But the idea is great.

 --End of <13341.1748637162@cvs.openbsd.org>

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)