Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932643Ab1CDWKl (ORCPT ); Fri, 4 Mar 2011 17:10:41 -0500 Received: from mail-yw0-f46.google.com ([209.85.213.46]:62733 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932606Ab1CDWKk convert rfc822-to-8bit (ORCPT ); Fri, 4 Mar 2011 17:10:40 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=EJOjzUAw50Gk1FRc6JSAM81jlj4dWvLayi/MJzWp8ROiMjwAaR5EYH78LfAfX/LYxQ 2sFzASznOzpFozxnnjqNrhusHCtretGdvTgFBBVnU+TioA/mmHJuJyt9iPYZCxdmmpc0 YOO1elWYutA34l7/M2S1IKzf5BWVCnMHOsxF0= MIME-Version: 1.0 In-Reply-To: <1299275042.2071.1422.camel@dan> References: <1299174652.2071.12.camel@dan> <1299185882.3062.233.camel@calx> <1299186986.2071.90.camel@dan> <1299188667.3062.259.camel@calx> <1299191400.2071.203.camel@dan> <2DD7330B-2FED-4E58-A76D-93794A877A00@mit.edu> <1299260164.8493.4071.camel@nimitz> <1299262495.3062.298.camel@calx> <1299270709.3062.313.camel@calx> <1299271377.2071.1406.camel@dan> <1299272907.2071.1415.camel@dan> <1299275042.2071.1422.camel@dan> Date: Sat, 5 Mar 2011 00:10:39 +0200 X-Google-Sender-Auth: nzBvSwX9Uh_1DJY03-k7IdLi0Ps Message-ID: Subject: Re: [PATCH] Make /proc/slabinfo 0400 From: Pekka Enberg To: Dan Rosenberg Cc: Matt Mackall , Linus Torvalds , Dave Hansen , Theodore Tso , cl@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1263 Lines: 31 Hi Dan, On Fri, Mar 4, 2011 at 11:44 PM, Dan Rosenberg wrote: > This is a good point, and one that I've come to accept as a result of > having this conversation. ?Consider the patch dropped, unless there are > other reasons I've missed. ?I still think it's worth brainstorming > techniques for hardening the kernel heap in ways that don't create > performance impact, but I admit that the presence or absence of this > debugging information isn't a crucial factor in successful exploitation. I can think of four things that will make things harder for the attacker (in the order of least theoretical performance impact): (1) disable slub merging (2) pin down random objects in the slab during setup (i.e. don't allow them to be allocated) (3) randomize the initial freelist (4) randomize padding between objects in a slab AFAICT, all of them will make brute force attacks using the kernel heap as an attack vector harder but won't prevent them. Pekka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/