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Date: Mon, 11 Mar 2024 12:05:11 -0700
From: enh <enh@...gle.com>
To: sjf5462@....edu
Cc: Florian Weimer <fweimer@...hat.com>, Andreas Schwab <schwab@...e.de>,
Alejandro Colomar <alx@...nel.org>, Thorsten Glaser <tg@...bsd.de>, Rich Felker <dalias@...c.org>,
musl@...ts.openwall.com, NRK <nrk@...root.org>,
Guillem Jover <guillem@...rons.org>, libc-alpha@...rceware.org,
libbsd@...ts.freedesktop.org, "Serge E. Hallyn" <serge@...lyn.com>,
Iker Pedrosa <ipedrosa@...hat.com>, Christian Brauner <christian@...uner.io>
Subject: Re: Re: Tweaking the program name for <err.h> functions
Android's libc actually does do this for everything except for
first-stage `init`, the one process that doesn't have a /dev/null
equivalent available yet:
https://android.googlesource.com/platform/bionic/+/master/libc/bionic/libc_init_common.cpp#358
On Mon, Mar 11, 2024 at 11:49 AM Skyler Ferrante (RIT Student)
<sjf5462@....edu> wrote:
>
> Hi Florian,
>
> > it's not running SUID (in AT_SECURE mode)
>
> I see. I didn't realize that it had different behavior for setuid/not
> setuid. That makes sense though, sorry for the confusion.
>
> Skyler
>
>
> On Mon, Mar 11, 2024 at 2:23 PM Florian Weimer <fweimer@...hat.com> wrote:
> >
> > * Skyler Ferrante:
> >
> > > Hmm, maybe I'm missing something, but it seems you can close(fd) for
> > > the standard fds and then call execve, and the new process image will
> > > have no fd 0,1,2. I've tried this on a default Ubuntu 22.04 system.
> > > This seems to affect shadow-utils and other setuid/setgid binaries.
> > >
> > > Here is a repo I built for testing,
> > > https://github.com/skyler-ferrante/fd_omission/. What is the correct
> > > glibc behavior? Am I misunderstanding something?
> >
> > If you run it under strace, it's not running SUID (in AT_SECURE mode).
> > I'm not saying we don't have bugs (although we do have some end-to-end
> > AT_SECURE tests in the testsuite, but probably not for this legacy
> > behavior), just that this approach to testing is questionable.
> >
> > Thanks,
> > Florian
> >
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