Date: Tue, 6 Sep 2011 21:29:52 +0400 From: Vasiliy Kulikov <segoon@...nwall.com> To: Tejun Heo <tj@...nel.org> Cc: Cyrill Gorcunov <gorcunov@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, "Kirill A. Shutemov" <kirill@...temov.name>, containers@...ts.osdl.org, linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, Nathan Lynch <ntl@...ox.com>, kernel-hardening@...ts.openwall.com, Oren Laadan <orenl@...columbia.edu>, Daniel Lezcano <dlezcano@...ibm.com>, Glauber Costa <glommer@...allels.com>, James Bottomley <jbottomley@...allels.com>, Alexey Dobriyan <adobriyan@...il.com>, Al Viro <viro@...IV.linux.org.uk>, Pavel Emelyanov <xemul@...allels.com> Subject: Re: [patch 2/2] fs, proc: Introduce the /proc/<pid>/map_files/ directory v6 Hi Tejun, On Wed, Sep 07, 2011 at 01:51 +0900, Tejun Heo wrote: > On Tue, Sep 06, 2011 at 02:15:18PM +0400, Vasiliy Kulikov wrote: > > c) If dentry is lazily dropped on each access attempt (or each illegal > > access) then PID2 can: > > > > i) read dentry line of /proc/slabinfo > > ii) call link(2) against /proc/PID/fd, which invalidates the > > specific dentry > > iii) re-read dentry line of /proc/slabinfo. If it has decreased by > > one, the dentry existed before (ii). > > If we really worry about this, probably the right thing to do is > hiding slabinfo from mortal UIDs instead of worrying about what > exactly are freed or not from each user. I agree with you. I don't think that showing system-global debug information to all users by default is the right thing. But some people doesn't agree with this point of view: http://thread.gmane.org/gmane.linux.kernel/1108378 -- Vasiliy Kulikov http://www.openwall.com - bringing security into open computing environments
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