From: Lennart Poettering <mzxreary@0pointer.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Ballard <dan@mindstab.net>,
Randy Dunlap <rdunlap@xenotime.net>, Ingo Molnar <mingo@elte.hu>,
Kay Sievers <kay.sievers@vrfy.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] kernel/sysctl.c: Add cap_last_cap to /proc/sys/kernel
Date: Thu, 20 Oct 2011 01:09:09 +0200 [thread overview]
Message-ID: <20111019230909.GB32295@tango.0pointer.de> (raw)
In-Reply-To: <20111017153936.c47a27ff.akpm@linux-foundation.org>
On Mon, 17.10.11 15:39, Andrew Morton (akpm@linux-foundation.org) wrote:
>
> On Sat, 15 Oct 2011 07:50:05 -0700
> Dan Ballard <dan@mindstab.net> wrote:
>
> > Userspace needs to know the highest valid capability of the running
> > kernel, which right now cannot reliably be retrieved from the header
> > files only. The fact that this value cannot be determined properly
> > right now creates various problems for libraries compiled on newer
> > header files which are run on older kernels. They assume
> > capabilities are available which actually aren't.
>
> Specfically, what libraries are we talking about here?
libcap-ng, for example. And we ran into the same problem with systemd too.
>
> > Now the capability is exported in /proc/sys/kernel/cap_last_cap.
>
> Ever the optimist: is there any way in which we can avoid 0444
> permissions on this?
Normal users should be able to query this value, and it's not a security
problem if they do. Hence 0444 appears to be the right setting to me.
Lennart
--
Lennart Poettering - Red Hat, Inc.
prev parent reply other threads:[~2011-10-19 23:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-12 22:56 [PATCH 1/1] added code to export CAP_LAST_CAP in /proc/sys/kernel modeled after ngroups_max Dan Ballard
2011-10-14 20:51 ` Andrew Morton
2011-10-15 14:50 ` [PATCH 1/1] kernel/sysctl.c: Add cap_last_cap to /proc/sys/kernel Dan Ballard
2011-10-17 22:39 ` Andrew Morton
2011-10-19 23:09 ` Lennart Poettering [this message]
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