From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 56D7D9000BD for ; Mon, 19 Sep 2011 14:21:18 -0400 (EDT) Received: by ewy25 with SMTP id 25so1197414ewy.14 for ; Mon, 19 Sep 2011 11:21:15 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1316455395.16137.160.camel@nimitz> References: <20110910164134.GA2442@albatros> <20110914192744.GC4529@outflux.net> <20110918170512.GA2351@albatros> <20110919144657.GA5928@albatros> <20110919155718.GB16272@albatros> <20110919161837.GA2232@albatros> <20110919173539.GA3751@albatros> <1316455395.16137.160.camel@nimitz> Date: Mon, 19 Sep 2011 21:21:15 +0300 Message-ID: Subject: Re: [kernel-hardening] Re: [RFC PATCH 2/2] mm: restrict access to /proc/slabinfo From: Pekka Enberg Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Vasiliy Kulikov , Andrew Morton , kernel-hardening@lists.openwall.com, Kees Cook , Cyrill Gorcunov , Al Viro , Christoph Lameter , Matt Mackall , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dan Rosenberg , Theodore Tso , Alan Cox , Jesper Juhl , Linus Torvalds On Mon, 2011-09-19 at 20:51 +0300, Pekka Enberg wrote: >> How is the attacker able to identify that we kmalloc()'d from ecryptfs o= r >> VFS based on non-root /proc/slabinfo when the slab allocator itself does >> not have that sort of information if you mix up the allocations? Isn't t= his >> much stronger protection especially if you combine that with /proc/slabi= nfo >> restriction? On Mon, Sep 19, 2011 at 9:03 PM, Dave Hansen wrot= e: > Mixing it up just adds noise. =A0It makes the attack somewhat more > difficult, but it still leaves open the possibility that the attacker > can filter out the noise somehow. So that would mean the attacker has somewhat fine-grained control over kernel memory allocations, no? Can they use /proc/meminfo to deduce the same kind of information? Should we close that down too? Pekka -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org