From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B2BDC433DB for ; Thu, 4 Feb 2021 22:52:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CDA9264FAC for ; Thu, 4 Feb 2021 22:52:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229823AbhBDWwV (ORCPT ); Thu, 4 Feb 2021 17:52:21 -0500 Received: from jabberwock.ucw.cz ([46.255.230.98]:40230 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229771AbhBDWwT (ORCPT ); Thu, 4 Feb 2021 17:52:19 -0500 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 6B3AC1C0B77; Thu, 4 Feb 2021 23:51:37 +0100 (CET) Date: Thu, 4 Feb 2021 23:51:36 +0100 From: Pavel Machek To: Kees Cook Cc: Timur Tabi , Steven Rostedt , Petr Mladek , Sergey Senozhatsky , linux-kernel@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, roman.fietze@magna.com, john.ogness@linutronix.de, akinobu.mita@gmail.com Subject: Re: [PATCH] lib/vsprintf: make-printk-non-secret printks all addresses as unhashed Message-ID: <20210204225136.GC13103@amd> References: <20210202201846.716915-1-timur@kernel.org> <20210204204835.GA7529@amd> <20210204155423.2864bf4f@gandalf.local.home> <20210204214944.GA13103@amd> <873d7e08-7a70-a1a3-f486-882d1d515965@kernel.org> <20210204221143.GB13103@amd> <202102041415.D9093ED6@keescook> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="lCAWRPmW1mITcIfM" Content-Disposition: inline In-Reply-To: <202102041415.D9093ED6@keescook> User-Agent: Mutt/1.5.23 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --lCAWRPmW1mITcIfM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu 2021-02-04 14:17:13, Kees Cook wrote: > On Thu, Feb 04, 2021 at 11:11:43PM +0100, Pavel Machek wrote: > > On Thu 2021-02-04 15:59:21, Timur Tabi wrote: > > > On 2/4/21 3:49 PM, Pavel Machek wrote: > > > >This machine is insecure. Yet I don't see ascii-art *** all around.. > > > > > > > >"Kernel memory addresses are exposed, which is bad for security." > > >=20 > > > I'll use whatever wording everyone can agree on, but I really don't s= ee much > > > difference between "which may compromise security on your system" and= "which > > > is bad for security". "may compromise" doesn't see any more alarmist= than > > > "bad". Frankly, "bad" is a very generic term. > >=20 > > Well, I agree that "bad" is vague.... but original wording is simply > > untrue, as printing addresses decreases robustness but can't introduce > > security problem on its own. > >=20 > > Being alarmist is not my complaint; being untrue is. >=20 > It's just semantics. Printing addresses DOES weaken the security of a > system, especially when we know attackers have and do use stuff from dmesg > to tune their attacks. How about "reduces the security of your system"? "reduces" sounds okay to me. You should not have attackers on your system. That reduces your security. You should not have users reading dmesg. Again that reduces your security. You should not have bugs in your kernel. That reduces your security. But you really can't have attackers patching your kernel. That compromises your security completely. Best regards, Pavel --=20 http://www.livejournal.com/~pavelmachek --lCAWRPmW1mITcIfM Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAmAcengACgkQMOfwapXb+vLwIQCggID0EEu00qFUtoLk+ZKgVWU4 lFEAnilwNvaSM1ZHIQg883HlE7F3ptDc =FGY9 -----END PGP SIGNATURE----- --lCAWRPmW1mITcIfM--