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From: Christian Brauner <christian.brauner@ubuntu.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Jann Horn <jannh@google.com>, Kees Cook <keescook@chromium.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Eric Biggers <ebiggers3@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-security-module <linux-security-module@vger.kernel.org>,
	Linux API <linux-api@vger.kernel.org>,
	kernel list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/4] exec: Change uselib(2) IS_SREG() failure to EACCES
Date: Tue, 19 May 2020 10:11:34 +0200	[thread overview]
Message-ID: <20200519081134.voejjt77b3qjf22h@wittgenstein> (raw)
In-Reply-To: <87blmk3ig4.fsf@x220.int.ebiederm.org>

On Mon, May 18, 2020 at 06:57:15PM -0500, Eric W. Biederman wrote:
> Christian Brauner <christian.brauner@ubuntu.com> writes:
> 
> > On Mon, May 18, 2020 at 04:43:20PM +0200, Jann Horn wrote:
> >> On Mon, May 18, 2020 at 3:03 PM Christian Brauner
> >> <christian.brauner@ubuntu.com> wrote:
> >> > Also - gulp (puts on flame proof suit) - may I suggest we check if there
> >> > are any distros out there that still set CONFIG_USELIB=y
> >> 
> >> Debian seems to have it enabled on x86...
> >> 
> >> https://salsa.debian.org/kernel-team/linux/-/blob/master/debian/config/kernelarch-x86/config#L1896
> >> 
> >> A random Ubuntu 19.10 VM I have here has it enabled, too.
> >
> > I wonder if there's any program - apart from _ancient_ glibc out there
> > that actually use it...
> > I looked at uselib in codsearch but the results were quite unspecific
> > but I didn't look too close.
> 
> So the thing to do is to have a polite word with people who build Ubuntu
> and Debian kernels and get them to disable the kernel .config.

Yeah, I think that's a sane thing to do.
I filed a bug for Ubuntu to start a discussion. I can't see an obvious
reason why not.

> 
> A quick look suggets it is already disabled in RHEL8.  It cannot be
> disabled in RHEL7.
> 
> Then in a few years we can come back and discuss removing the uselib
> system call, base on no distributions having it enabled.
> 
> If it was only libc4 and libc5 that used the uselib system call then it
> can probably be removed after enough time.
> 
> We can probably reorganize the code before the point it is clearly safe
> to drop support for USELIB to keep it off to the side so USELIB does not
> have any ongoing mainteance costs.
> 
> For this patchset I think we need to assume uselib will need to be
> maintained for a bit longer.

Yeah, agreed. It doesn't matter as long as we have a plan for the future
to remove it. I don't think keeping this cruft around forever should be
the only outlook.

Christian

  reply	other threads:[~2020-05-19  8:12 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-18  5:54 [PATCH 0/4] Relocate execve() sanity checks Kees Cook
2020-05-18  5:54 ` [PATCH 1/4] exec: Change uselib(2) IS_SREG() failure to EACCES Kees Cook
2020-05-18 13:02   ` Christian Brauner
2020-05-18 14:43     ` Jann Horn
2020-05-18 14:46       ` Christian Brauner
2020-05-18 23:57         ` Eric W. Biederman
2020-05-19  8:11           ` Christian Brauner [this message]
2020-05-19  8:37           ` Andreas Schwab
2020-05-19 11:56             ` Eric W. Biederman
2020-05-19 12:12               ` Andreas Schwab
2020-05-19 12:28                 ` Eric W. Biederman
2020-05-19 13:29                   ` Christian Brauner
2020-05-19 14:49                     ` Eric W. Biederman
2020-05-19 13:13               ` Christian Brauner
2020-05-19 14:32                 ` Geert Uytterhoeven
2020-05-19 14:47                   ` Christian Brauner
2020-05-18  5:54 ` [PATCH 2/4] exec: Relocate S_ISREG() check Kees Cook
     [not found]   ` <20200525091420.GI12456@shao2-debian>
2020-06-04 22:45     ` [exec] 166d03c9ec: ltp.execveat02.fail Kees Cook
2020-06-05  2:57     ` Kees Cook
2020-05-18  5:54 ` [PATCH 3/4] exec: Relocate path_noexec() check Kees Cook
2020-05-18  5:54 ` [PATCH 4/4] fs: Include FMODE_EXEC when converting flags to f_mode Kees Cook
2020-05-19 15:06 ` [PATCH 0/4] Relocate execve() sanity checks Eric W. Biederman
2020-05-19 16:26   ` Kees Cook
2020-05-19 17:41     ` Eric W. Biederman
2020-05-19 17:56       ` Kees Cook
2020-05-19 18:42         ` Eric W. Biederman
2020-05-19 21:17           ` Kees Cook
2020-05-19 22:58             ` John Johansen

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