From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Vasiliy Kulikov <segoon@openwall.com>
Cc: 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>,
Tejun Heo <tj@kernel.org>, 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 00:36:27 +0400 [thread overview]
Message-ID: <20110905203627.GL761@sun> (raw)
In-Reply-To: <20110905194908.GA2690@albatros>
On Mon, Sep 05, 2011 at 11:49:08PM +0400, Vasiliy Kulikov wrote:
...
>
> Actually, it can be speed up by introducing the same ptrace check. If
> ptrace check fails, then just drop the dentry, otherwise continue to use
> it. Then each revalidate would trigger ptrace check instead of full
> drop-lookup-alloc cycle. If one process actively looks into
> map_files/ or fd/, it will not become significantly slower. However, it
> will trigger 2 capable() fail alerts in ptrace_may_access() instead of
> one :)
Hmm, at least it's better than trashing dcache I think.
>
> But I still see one very nasty issue - one may trigger this ptrace check,
> trigger d_drop() and then look at /proc/slabinfo at "dentry" row. If
> the number has changed, then the interested dentry existed before the
> revalidate call. This infoleak is tricky to fix without any race.
>
> Probably it's time to close /proc/slabinfo infoleak?
>
Actually I miss to see how exactly this infoleak can be used by attacker
or whoever. So, Vasiliy, what the security issue there?
Cyrill
next prev parent reply other threads:[~2011-09-05 20:36 UTC|newest]
Thread overview: 54+ 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 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
2011-09-05 18:53 ` Vasiliy Kulikov
2011-09-05 19:20 ` Cyrill Gorcunov
2011-09-05 19:49 ` Vasiliy Kulikov
2011-09-05 20:36 ` Cyrill Gorcunov [this message]
2011-09-06 10:15 ` Vasiliy Kulikov
2011-09-06 16:51 ` Tejun Heo
2011-09-06 17:29 ` Vasiliy Kulikov
2011-09-06 17:33 ` Tejun Heo
2011-09-06 18:15 ` Cyrill Gorcunov
[not found] ` <20110906173341.GM18425-9pTldWuhBndy/B6EtB590w@public.gmane.org>
2011-09-07 11:23 ` Vasiliy Kulikov
2011-09-07 21:53 ` Cyrill Gorcunov
2011-09-07 22:13 ` Andrew Morton
2011-09-07 22:42 ` Cyrill Gorcunov
2011-09-07 22:53 ` Andrew Morton
2011-09-08 5:48 ` Cyrill Gorcunov
2011-09-08 5:50 ` Cyrill Gorcunov
2011-09-08 6:04 ` Cyrill Gorcunov
2011-09-08 23:52 ` Andrew Morton
2011-09-09 0:24 ` Pavel Emelyanov
2011-09-09 5:48 ` Cyrill Gorcunov
2011-09-09 6:00 ` Andrew Morton
2011-09-09 6:22 ` Cyrill Gorcunov
2011-09-10 13:21 ` [kernel-hardening] " 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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