From: Vasiliy Kulikov <segoon@openwall.com>
To: Tejun Heo <tj@kernel.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
containers@lists.osdl.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, Nathan Lynch <ntl@pobox.com>,
kernel-hardening@lists.openwall.com,
Oren Laadan <orenl@cs.columbia.edu>,
Daniel Lezcano <dlezcano@fr.ibm.com>,
Glauber Costa <glommer@parallels.com>,
James Bottomley <jbottomley@parallels.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Al Viro <viro@ZenIV.linux.org.uk>,
Pavel Emelyanov <xemul@parallels.com>
Subject: Re: [patch 2/2] fs, proc: Introduce the /proc/<pid>/map_files/ directory v6
Date: Tue, 6 Sep 2011 21:29:52 +0400 [thread overview]
Message-ID: <20110906172952.GA28055@albatros> (raw)
In-Reply-To: <20110906165144.GJ18425@mtj.dyndns.org>
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
WARNING: multiple messages have this Message-ID (diff)
From: Vasiliy Kulikov <segoon@openwall.com>
To: Tejun Heo <tj@kernel.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
containers@lists.osdl.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, Nathan Lynch <ntl@pobox.com>,
kernel-hardening@lists.openwall.com,
Oren Laadan <orenl@cs.columbia.edu>,
Daniel Lezcano <dlezcano@fr.ibm.com>,
Glauber Costa <glommer@parallels.com>,
James Bottomley <jbottomley@parallels.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Al Viro <viro@ZenIV.linux.org.uk>,
Pavel Emelyanov <xemul@parallels.com>
Subject: [kernel-hardening] Re: [patch 2/2] fs, proc: Introduce the /proc/<pid>/map_files/ directory v6
Date: Tue, 6 Sep 2011 21:29:52 +0400 [thread overview]
Message-ID: <20110906172952.GA28055@albatros> (raw)
In-Reply-To: <20110906165144.GJ18425@mtj.dyndns.org>
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
next prev parent reply other threads:[~2011-09-06 17:29 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-31 7:58 [patch 0/2] Introduce /proc/pid/map_files v6 Cyrill Gorcunov
2011-08-31 7:58 ` [patch 1/2] fs, proc: Make proc_get_link to use dentry instead of inode Cyrill Gorcunov
2011-08-31 7:58 ` [patch 2/2] fs, proc: Introduce the /proc/<pid>/map_files/ directory v6 Cyrill Gorcunov
2011-08-31 9:06 ` Vasiliy Kulikov
2011-08-31 10:12 ` Cyrill Gorcunov
2011-08-31 11:26 ` Cyrill Gorcunov
2011-08-31 14:04 ` Kirill A. Shutemov
2011-08-31 14:09 ` Cyrill Gorcunov
2011-08-31 14:26 ` Cyrill Gorcunov
2011-08-31 22:10 ` Andrew Morton
2011-09-01 3:07 ` Kyle Moffett
2011-09-01 3:07 ` Kyle Moffett
2011-09-01 7:58 ` Pavel Emelyanov
2011-09-01 11:50 ` Tejun Heo
2011-09-01 12:13 ` Pavel Emelyanov
2011-09-01 17:13 ` Tejun Heo
2011-09-02 19:15 ` Matt Helsley
2011-09-02 0:09 ` Matt Helsley
2011-09-01 8:05 ` Cyrill Gorcunov
2011-09-02 16:37 ` Vasiliy Kulikov
2011-09-02 16:37 ` [kernel-hardening] " Vasiliy Kulikov
2011-09-05 18:53 ` Vasiliy Kulikov
2011-09-05 18:53 ` [kernel-hardening] " Vasiliy Kulikov
2011-09-05 19:20 ` Cyrill Gorcunov
2011-09-05 19:20 ` [kernel-hardening] " Cyrill Gorcunov
2011-09-05 19:49 ` Vasiliy Kulikov
2011-09-05 19:49 ` [kernel-hardening] " Vasiliy Kulikov
2011-09-05 20:36 ` Cyrill Gorcunov
2011-09-05 20:36 ` [kernel-hardening] " Cyrill Gorcunov
2011-09-06 10:15 ` Vasiliy Kulikov
2011-09-06 10:15 ` [kernel-hardening] " Vasiliy Kulikov
2011-09-06 16:51 ` Tejun Heo
2011-09-06 16:51 ` [kernel-hardening] " Tejun Heo
2011-09-06 17:29 ` Vasiliy Kulikov [this message]
2011-09-06 17:29 ` Vasiliy Kulikov
2011-09-06 17:33 ` Tejun Heo
2011-09-06 17:33 ` [kernel-hardening] " Tejun Heo
2011-09-06 18:15 ` Cyrill Gorcunov
2011-09-06 18:15 ` [kernel-hardening] " Cyrill Gorcunov
[not found] ` <20110906173341.GM18425-9pTldWuhBndy/B6EtB590w@public.gmane.org>
2011-09-07 11:23 ` Vasiliy Kulikov
2011-09-07 11:23 ` [kernel-hardening] " Vasiliy Kulikov
2011-09-07 21:53 ` Cyrill Gorcunov
2011-09-07 21:53 ` [kernel-hardening] " Cyrill Gorcunov
2011-09-07 22:13 ` Andrew Morton
2011-09-07 22:13 ` Andrew Morton
2011-09-07 22:13 ` [kernel-hardening] " Andrew Morton
2011-09-07 22:42 ` Cyrill Gorcunov
2011-09-07 22:42 ` [kernel-hardening] " Cyrill Gorcunov
2011-09-07 22:53 ` Andrew Morton
2011-09-07 22:53 ` Andrew Morton
2011-09-07 22:53 ` [kernel-hardening] " Andrew Morton
2011-09-08 5:48 ` Cyrill Gorcunov
2011-09-08 5:48 ` [kernel-hardening] " Cyrill Gorcunov
2011-09-08 5:50 ` Cyrill Gorcunov
2011-09-08 5:50 ` [kernel-hardening] " Cyrill Gorcunov
2011-09-08 6:04 ` Cyrill Gorcunov
2011-09-08 6:04 ` [kernel-hardening] " Cyrill Gorcunov
2011-09-08 23:52 ` Andrew Morton
2011-09-08 23:52 ` Andrew Morton
2011-09-08 23:52 ` [kernel-hardening] " Andrew Morton
2011-09-09 0:24 ` Pavel Emelyanov
2011-09-09 0:24 ` [kernel-hardening] " Pavel Emelyanov
2011-09-09 5:48 ` Cyrill Gorcunov
2011-09-09 5:48 ` [kernel-hardening] " Cyrill Gorcunov
2011-09-09 6:00 ` Andrew Morton
2011-09-09 6:00 ` [kernel-hardening] " Andrew Morton
2011-09-09 6:22 ` Cyrill Gorcunov
2011-09-09 6:22 ` [kernel-hardening] " Cyrill Gorcunov
2011-09-10 13:21 ` Vasiliy Kulikov
2011-09-10 13:49 ` Cyrill Gorcunov
2011-09-01 10:46 ` Cyrill Gorcunov
2011-09-01 22:49 ` Andrew Morton
2011-09-01 23:04 ` Tejun Heo
2011-09-02 5:54 ` Cyrill Gorcunov
2011-09-02 5:53 ` Cyrill Gorcunov
2011-08-31 22:50 ` Andrew Morton
2011-09-02 1:54 ` Nicholas Miell
2011-09-02 1:58 ` Tejun Heo
2011-09-02 2:04 ` Nicholas Miell
2011-09-02 2:29 ` Tejun Heo
2011-09-02 8:07 ` Kirill A. Shutemov
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