mailing list of musl libc
 help / color / mirror / code / Atom feed
From: Rich Felker <dalias@libc.org>
To: musl@lists.openwall.com
Subject: Re: [musl] [PATCH] accept4: don't fall back to accept if we got unknown flags
Date: Mon, 27 Feb 2023 17:38:23 -0500	[thread overview]
Message-ID: <20230227223822.GH4163@brightrain.aerifal.cx> (raw)
In-Reply-To: <20230227194654.61114-1-izbyshev@ispras.ru>

On Mon, Feb 27, 2023 at 10:46:54PM +0300, Alexey Izbyshev wrote:
> accept4 emulation via accept ignores unknown flags, so it can spuriously
> succeed instead of failing (or succeed without doing the action implied
> by an unknown flag if it's added in a future kernel). Worse, unknown
> flags trigger the fallback code even on modern kernels if the real
> accept4 syscall returns EINVAL, because this is indistinguishable from
> socketcall returning EINVAL due to lack of accept4 support. Fix this by
> always propagating the syscall attempt failure if unknown flags are
> present.
> 
> The behavior is still not ideal on old kernels lacking accept4 on arches
> with socketcall, where failing with ENOSYS instead of EINVAL returned by
> socketcall would be preferable, but at least modern kernels are now
> fine.

Can you clarify what you mean about ENOSYS vs EINVAL here? I'm not
following.

Rich

  reply	other threads:[~2023-02-27 22:38 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-27 19:46 Alexey Izbyshev
2023-02-27 22:38 ` Rich Felker [this message]
2023-02-27 23:42   ` Alexey Izbyshev
2023-02-27 23:51     ` Alexey Izbyshev
2023-02-27 23:53       ` Rich Felker
2023-02-28 17:21     ` Rich Felker
2023-02-28 17:25       ` Rich Felker
2023-02-28 20:15         ` Alexey Izbyshev
2023-02-28 20:51           ` Rich Felker

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20230227223822.GH4163@brightrain.aerifal.cx \
    --to=dalias@libc.org \
    --cc=musl@lists.openwall.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://git.vuxu.org/mirror/musl/

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).