From: Al Viro <viro@ZenIV.linux.org.uk>
To: Kees Cook <kees.cook@canonical.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org,
Randy Dunlap <rdunlap@xenotime.net>,
Andrew Morton <akpm@linux-foundation.org>,
Jiri Kosina <jkosina@suse.cz>,
Dave Young <hidave.darkstar@gmail.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
James Morris <jmorris@namei.org>, Eric Paris <eparis@redhat.com>,
David Howells <dhowells@redhat.com>, Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Tim Gardner <tim.gardner@canonical.com>,
"Serge E. Hallyn" <serue@us.ibm.com>
Subject: Re: [PATCH v2] fs: block cross-uid sticky symlinks
Date: Mon, 31 May 2010 20:52:30 +0100 [thread overview]
Message-ID: <20100531195230.GS31073@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20100531190754.GF4098@outflux.net>
On Mon, May 31, 2010 at 12:07:54PM -0700, Kees Cook wrote:
> IIRC, screen, when setuid, allows users to share screen sessions (following
> some system-defined ACLs) but it does it via the /tmp directory trees it
> creates. Per-user /tmp would break this (but yes, it's solvable using some
> kind of /var/lib/screen which maybe even already exists).
screen(1) does *not* put directories in /tmp these days, TYVM.
al@duke:~/linux/trees/vfs-next$ ls -l /var/run/screen/
total 1
drwx------ 2 al al 1024 May 20 21:50 S-al
That's lenny/x86_64; I can't be arsed to install ubuntu, but in case you
have a really ancient screen(1), pulling one from debian -stable would
suffice. IIRC, -oldstable would work as well, actually, but I could be
wrong on that.
In any case, the suggested "improvement" breaks realistic use cases, AFAICS.
In particular,
cd /tmp
tar jxf foo-2.42.orig.tar.bz2
<...>
tar jxf foo-gtk-wank-wank-wank-2.69.orig.tar.bz2
<...>
ln -s foo-gtk-wank-wank-wank-2.69/docs/GNOME/design/ crap
<...>
lpr crap/taste-is-optional.ps
lpr crap/why-options-are-wrong.ps
is going to break with that, isn't it?
next prev parent reply other threads:[~2010-05-31 19:52 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-31 3:04 [PATCH v2] fs: block cross-uid sticky symlinks Kees Cook
2010-05-31 3:50 ` Eric W. Biederman
2010-05-31 4:12 ` Kees Cook
2010-05-31 3:54 ` Eric Paris
2010-05-31 4:23 ` Kees Cook
2010-05-31 10:23 ` Alan Cox
2010-05-31 17:50 ` Kees Cook
2010-05-31 18:09 ` Alan Cox
2010-05-31 19:07 ` Kees Cook
2010-05-31 19:52 ` Al Viro [this message]
2010-05-31 22:00 ` Kees Cook
2010-05-31 19:27 ` Al Viro
2010-05-31 10:35 ` Christoph Hellwig
2010-05-31 17:57 ` Kees Cook
2010-05-31 23:09 ` James Morris
2010-06-01 3:24 ` Kees Cook
2010-06-01 7:55 ` Christoph Hellwig
2010-06-01 11:55 ` Eric Paris
2010-06-01 14:52 ` Kees Cook
2010-06-01 15:34 ` Eric Paris
2010-06-01 17:31 ` tytso
2010-06-01 15:00 ` Kees Cook
2010-05-31 10:47 ` tytso
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