Date: Tue, 4 Oct 2011 17:31:26 +0400 From: Vasiliy Kulikov <segoon@...nwall.com> To: Adrian Bunk <bunk@...sta.de> Cc: Guillaume Chazarain <guichaz@...il.com>, Linus Torvalds <torvalds@...ux-foundation.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Balbir Singh <bsingharora@...il.com>, kernel-hardening@...ts.openwall.com, Andrew Morton <akpm00@...il.com> Subject: Re: taskstats root only breaking iotop On Mon, Oct 03, 2011 at 15:31 +0300, Adrian Bunk wrote: > On Sun, Oct 02, 2011 at 02:54:57PM +0400, Vasiliy Kulikov wrote: > > (cc'ed kernel-hardening) > > > > On Sun, Oct 02, 2011 at 12:22 +0200, Guillaume Chazarain wrote: > > > On Sun, Oct 2, 2011 at 2:20 AM, Linus Torvalds > > > <torvalds@...ux-foundation.org> wrote: > > > > So I don't see why you ask for it. What could possibly be a valid use-case? > > > > > > Right, kbyte granularity is enough. > > > > It is not enough. In some border cases an attacker may still learn > > private information given the counters with _arbitrary_ granularity: > > > > http://www.openwall.com/lists/oss-security/2011/06/29/9 > > If you request a CVE for that, shouldn't there also be a CVE for > /proc/<pid>/cmdline being readable by all users? > > I'd expect "ps -ef" to be more likely to give private information to an > attacker than counters with kbyte granularity, or am I wrong on that? I agree that world-readable cmdline can be a privacy issue in some cases. I tried to push a patch introducing procfs mount option to restrict /proc/PID/ to PID owner to address the issue (as world-readable cmdline and other files are already used by plenty of programs and unconditionally breaking backward compatibility is not good, a configuration mechanism is needed), but it didn't receive positive feedback. A more detailed explanation from Solar Designer: http://www.openwall.com/lists/kernel-hardening/2011/06/20/5 Andrew Morton complained that it is too specific to our needs and one might want to define more fine granted procfs security model: http://www.openwall.com/lists/kernel-hardening/2011/06/21/3 I've tried to address it and defined per-file policy: http://www.openwall.com/lists/kernel-hardening/2011/08/10/12 No comments so far :( -- Vasiliy Kulikov http://www.openwall.com - bringing security into open computing environments
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