From: Vasiliy Kulikov <segoon@openwall.com>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Andrew Morton <akpm@linux-foundation.org>,
kernel-hardening@lists.openwall.com, Kees Cook <kees@ubuntu.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Christoph Lameter <cl@linux-foundation.org>,
Matt Mackall <mpm@selenic.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Dan Rosenberg <drosenberg@vsecurity.com>,
Theodore Tso <tytso@mit.edu>, Alan Cox <alan@linux.intel.com>,
Jesper Juhl <jj@chaosbits.net>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [kernel-hardening] Re: [RFC PATCH 2/2] mm: restrict access to /proc/slabinfo
Date: Mon, 19 Sep 2011 21:35:39 +0400 [thread overview]
Message-ID: <20110919173539.GA3751@albatros> (raw)
In-Reply-To: <CAOJsxLE2od0f+6cbL2hA_31CbrqS7AUofx5DT2L9fO_7gxH+PQ@mail.gmail.com>
On Mon, Sep 19, 2011 at 20:31 +0300, Pekka Enberg wrote:
> On Mon, Sep 19, 2011 at 7:18 PM, Vasiliy Kulikov <segoon@openwall.com> wrote:
> >> However, if the encryptfs and infoleaks really are serious enough to
> >> hide /proc/slabinfo, I think you should consider switching over to
> >> kmalloc() instead of kmem_cache_alloc() to make sure nobody can
> >> gain access to the information.
> >
> > 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.
Thanks,
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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next prev parent reply other threads:[~2011-09-19 17:36 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20110910164001.GA2342@albatros>
2011-09-10 16:41 ` [RFC PATCH 2/2] mm: restrict access to /proc/slabinfo Vasiliy Kulikov
2011-09-12 15:06 ` Cyrill Gorcunov
2011-09-13 6:28 ` Vasiliy Kulikov
2011-09-14 13:16 ` Vasiliy Kulikov
2011-09-14 15:18 ` Dave Hansen
2011-09-14 15:42 ` [kernel-hardening] " Vasiliy Kulikov
2011-09-14 15:48 ` Vasiliy Kulikov
2011-09-14 18:24 ` Dave Hansen
2011-09-14 18:41 ` Dave Hansen
2011-09-14 19:14 ` Vasiliy Kulikov
2011-09-14 19:27 ` Kees Cook
2011-09-18 17:05 ` [kernel-hardening] " Vasiliy Kulikov
2011-09-19 13:42 ` Christoph Lameter
2011-09-19 14:30 ` Pekka Enberg
2011-09-19 14:46 ` Vasiliy Kulikov
2011-09-19 15:13 ` Pekka Enberg
2011-09-19 15:57 ` Vasiliy Kulikov
2011-09-19 16:11 ` Pekka Enberg
2011-09-19 16:18 ` Vasiliy Kulikov
2011-09-19 17:31 ` Pekka Enberg
2011-09-19 17:35 ` Vasiliy Kulikov [this message]
2011-09-19 17:51 ` Christoph Lameter
2011-09-19 19:59 ` Valdis.Kletnieks
2011-09-19 20:02 ` Christoph Lameter
2011-09-19 20:36 ` Valdis.Kletnieks
2011-09-19 17:51 ` Pekka Enberg
2011-09-19 17:58 ` Vasiliy Kulikov
2011-09-19 18:46 ` Pekka Enberg
2011-09-19 18:55 ` Vasiliy Kulikov
2011-09-19 19:20 ` Pekka Enberg
2011-09-19 19:33 ` Pekka Enberg
2011-09-19 18:55 ` Linus Torvalds
2011-09-19 19:18 ` Pekka Enberg
2011-09-19 19:45 ` Pekka Enberg
2011-09-19 20:59 ` David Rientjes
2011-09-19 18:03 ` Dave Hansen
2011-09-19 18:21 ` Pekka Enberg
2011-09-19 19:45 ` Valdis.Kletnieks
2011-09-19 19:55 ` Alan Cox
2011-09-21 17:05 ` Vasiliy Kulikov
2011-09-22 2:20 ` Valdis.Kletnieks
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