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Date: Mon, 19 Sep 2011 12:51:10 -0500 (CDT)
From: Christoph Lameter <cl@...two.org>
To: Vasiliy Kulikov <segoon@...nwall.com>
cc: Pekka Enberg <penberg@...helsinki.fi>,
Andrew Morton <akpm@...ux-foundation.org>,
kernel-hardening@...ts.openwall.com, Kees Cook <kees@...ntu.com>,
Cyrill Gorcunov <gorcunov@...il.com>, Al Viro <viro@...iv.linux.org.uk>,
Christoph Lameter <cl@...ux-foundation.org>, Matt Mackall <mpm@...enic.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Dan Rosenberg <drosenberg@...curity.com>, Theodore Tso <tytso@....edu>,
Alan Cox <alan@...ux.intel.com>, Jesper Juhl <jj@...osbits.net>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: Re: [RFC PATCH 2/2] mm: restrict access to
/proc/slabinfo
On Mon, 19 Sep 2011, Vasiliy Kulikov wrote:
> > > kmalloc() is still visible in slabinfo as kmalloc-128 or so.
> >
> > Yes, but there's no way for users to know where the allocations came from
> > if you mix them up with other kmalloc-128 call-sites. That way the number
> > of private files will stay private to the user, no? Doesn't that give you even
> > better protection against the infoleak?
>
> No, what it gives us is an obscurity, not a protection. I'm sure it
> highly depends on the specific situation whether an attacker is able to
> identify whether the call is from e.g. ecryptfs or from VFS. Also the
> correlation between the number in slabinfo and the real private actions
> still exists.
IMHO a restriction of access to slab statistics is reasonable in a
hardened environment. Make it dependent on CONFIG_SECURITY or some such
thing?
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