From: Kees Cook <kees@outflux.net>
To: Nick Bowler <nbowler@elliptictech.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Linux 3.6
Date: Wed, 3 Oct 2012 13:05:15 -0700 [thread overview]
Message-ID: <20121003200515.GZ9092@outflux.net> (raw)
In-Reply-To: <20121003194614.GA2893@elliptictech.com>
Hi Nick,
3.6 introduced link restrictions:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=800179c9b8a1e796e441674776d11cd4c05d61d7
It sounds like you've got symlinks in a world-writable directory, and
you're following those symlinks across mis-matched uids. You can either
have the symlinks be owned by the directory owner, or you can turn off
symlink restrictions in sysctl:
# echo 0 > /proc/sys/fs/protected_symlinks
-Kees
On Wed, Oct 03, 2012 at 03:46:14PM -0400, Nick Bowler wrote:
> On 2012-09-30 17:38 -0700, Linus Torvalds wrote:
> > So here it is, 3.6 final. Sure, I'd have been happier with even fewer
> > changes, but that just never happens. And holding off the release
> > until people get too bored to send me the small stuff just makes the
> > next merge window more painful.
>
> Just upgraded to 3.6 from 3.5, and now some of my kernel build scripts
> are throwing "permission denied" errors. Apparently symlinks are
> broken somehow?
>
> # id
> uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel),11(floppy),20(dialout),26(tape),27(video)
>
> # ls -l /scratch_space/linux
> drwxr-xr-x 24 nbowler eng 4096 2012-10-03 13:41 /scratch_space/linux
>
> # readlink /scratch_space/linux-2.6
> linux
>
> # cd /scratch_space/linux
> # pwd
> /scratch_space/linux
>
> # cd /scratch_space/linux-2.6
> cd: permission denied: /scratch_space/linux-2.6
>
> WTF? 3.5 is fine. I will try to bisect this later, but I figured I'd
> throw this out there now in case anyone has any ideas...
>
> Cheers,
> --
> Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)
>
> --
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--
Kees Cook @outflux.net
next prev parent reply other threads:[~2012-10-03 20:05 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-01 0:38 Linux 3.6 Linus Torvalds
2012-10-03 19:46 ` Nick Bowler
2012-10-03 20:05 ` Kees Cook [this message]
2012-10-03 20:29 ` Linus Torvalds
2012-10-03 20:41 ` Theodore Ts'o
2012-10-03 20:49 ` Kees Cook
2012-10-03 20:54 ` Linus Torvalds
2012-10-03 20:58 ` Kees Cook
2012-10-03 21:05 ` Alan Cox
2012-10-03 21:04 ` Kees Cook
2012-10-04 13:35 ` Nick Bowler
2012-10-04 15:49 ` Kees Cook
2012-10-04 16:03 ` Nick Bowler
2012-10-04 16:14 ` Kees Cook
2012-10-04 17:16 ` Nick Bowler
2012-10-04 21:30 ` Stefan Richter
2012-10-09 18:51 ` Nick Bowler
2012-10-03 20:49 ` Alan Cox
2012-10-03 22:23 ` Matthias Schniedermeyer
2012-10-03 23:58 ` Theodore Ts'o
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