From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f70.google.com (mail-pa0-f70.google.com [209.85.220.70]) by kanga.kvack.org (Postfix) with ESMTP id 20A9E6B025F for ; Tue, 26 Jul 2016 17:06:33 -0400 (EDT) Received: by mail-pa0-f70.google.com with SMTP id pp5so1951184pac.3 for ; Tue, 26 Jul 2016 14:06:33 -0700 (PDT) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTP id gc6si2368423pab.18.2016.07.26.14.06.32 for ; Tue, 26 Jul 2016 14:06:32 -0700 (PDT) From: "Roberts, William C" Subject: RE: [PATCH] [RFC] Introduce mmap randomization Date: Tue, 26 Jul 2016 21:06:30 +0000 Message-ID: <476DC76E7D1DF2438D32BFADF679FC5601260068@ORSMSX103.amr.corp.intel.com> References: <1469557346-5534-1-git-send-email-william.c.roberts@intel.com> <1469557346-5534-2-git-send-email-william.c.roberts@intel.com> <20160726200309.GJ4541@io.lakedaemon.net> <476DC76E7D1DF2438D32BFADF679FC560125F29C@ORSMSX103.amr.corp.intel.com> <20160726205944.GM4541@io.lakedaemon.net> In-Reply-To: <20160726205944.GM4541@io.lakedaemon.net> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Jason Cooper Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "kernel-hardening@lists.openwall.com" , "akpm@linux-foundation.org" , "keescook@chromium.org" , "gregkh@linuxfoundation.org" , "nnk@google.com" , "jeffv@google.com" , "salyzyn@android.com" , "dcashman@android.com" > -----Original Message----- > From: owner-linux-mm@kvack.org [mailto:owner-linux-mm@kvack.org] On > Behalf Of Jason Cooper > Sent: Tuesday, July 26, 2016 2:00 PM > To: Roberts, William C > Cc: linux-mm@kvack.org; linux-kernel@vger.kernel.org; kernel- > hardening@lists.openwall.com; akpm@linux-foundation.org; > keescook@chromium.org; gregkh@linuxfoundation.org; nnk@google.com; > jeffv@google.com; salyzyn@android.com; dcashman@android.com > Subject: Re: [PATCH] [RFC] Introduce mmap randomization >=20 > Hi William, >=20 > On Tue, Jul 26, 2016 at 08:13:23PM +0000, Roberts, William C wrote: > > > > From: Jason Cooper [mailto:jason@lakedaemon.net] On Tue, Jul 26, > > > > 2016 at 11:22:26AM -0700, william.c.roberts@intel.com wrote: > > > > > Performance Measurements: > > > > > Using strace with -T option and filtering for mmap on the > > > > > program ls shows a slowdown of approximate 3.7% > > > > > > > > I think it would be helpful to show the effect on the resulting obj= ect code. > > > > > > Do you mean the maps of the process? I have some captures for > > > whoopsie on my Ubuntu system I can share. >=20 > No, I mean changes to mm/mmap.o. Sure I can post the objdump of that, do you just want a diff of old vs new? >=20 > > > One thing I didn't make clear in my commit message is why this is > > > good. Right now, if you know An address within in a process, you > > > know all offsets done with mmap(). For instance, an offset To libX > > > can yield libY by adding/subtracting an offset. This is meant to > > > make rops a bit harder, or In general any mapping offset mmore diffic= ult to > find/guess. >=20 > Are you able to quantify how many bits of entropy you're imposing on the > attacker? Is this a chair in the hallway or a significant increase in th= e chances of > crashing the program before finding the desired address? I'd likely need to take a small sample of programs and examine them, especi= ally considering That as gaps are harder to find, it forces the randomization down and rando= mization can Be directly altered with length on mmap(), versus randomize_addr() which di= dn't have this restriction but OOM'd do to fragmented easier. >=20 > thx, >=20 > Jason. >=20 > -- > 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/ . > Don't email: email@kvack.org -- 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/ . Don't email: email@kvack.org