Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753141Ab2JCUFT (ORCPT ); Wed, 3 Oct 2012 16:05:19 -0400 Received: from smtp.outflux.net ([198.145.64.163]:51922 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752698Ab2JCUFS (ORCPT ); Wed, 3 Oct 2012 16:05:18 -0400 Date: Wed, 3 Oct 2012 13:05:15 -0700 From: Kees Cook To: Nick Bowler Cc: Linus Torvalds , Linux Kernel Mailing List Subject: Re: Linux 3.6 Message-ID: <20121003200515.GZ9092@outflux.net> References: <20121003194614.GA2893@elliptictech.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121003194614.GA2893@elliptictech.com> Organization: Outflux X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2247 Lines: 61 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/) > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Kees Cook @outflux.net -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/