Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967478AbeAOMzz (ORCPT + 1 other); Mon, 15 Jan 2018 07:55:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:42216 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966049AbeAOMwe (ORCPT ); Mon, 15 Jan 2018 07:52:34 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D741E21795 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Date: Mon, 15 Jan 2018 07:52:31 -0500 From: Steven Rostedt To: Dan Aloni Cc: Sergey Senozhatsky , linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, Petr Mladek , Linus Torvalds , Peter Zijlstra , Andrew Morton , Kees Cook Subject: Re: [PATCHv2 5/7] printk: allow kmsg to be encrypted using public key encryption Message-ID: <20180115075231.0d435fec@gandalf.local.home> In-Reply-To: <20180114080108.GA69022@gmail.com> References: <20180113213441.52047-1-dan@kernelim.com> <20180113213441.52047-6-dan@kernelim.com> <20180114014801.GC1701@tigerII.localdomain> <20180114080108.GA69022@gmail.com> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Sun, 14 Jan 2018 10:01:08 +0200 Dan Aloni wrote: > On Sun, Jan 14, 2018 at 10:48:01AM +0900, Sergey Senozhatsky wrote: > > Ccing Kees, Peter, Andrew, Steven > > > > On (01/13/18 23:34), Dan Aloni wrote: > > > This commit enables the kernel to encrypt the free-form text that > > > is generated by printk() before it is brought up to `dmesg` in > > > userspace. > > > > > > The encryption is made using one of the trusted public keys which > > > are kept built-in inside the kernel. These keys are presently > > > also used for verifying kernel modules and userspace-supplied > > > firmwares. > > > > OK, this is the first time I'm receiving it, yet it's v2 already. > > I'm Cc-ed on only this particular patch, not the entire patch set; > > so it's hard to tell what else is being touched and why, so I'm > > going to start with the basic questions. > > Sorry, here the link to cover letter: > > https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1585442.html > > I guess --cc-cover && --to-cover should be default. > > > are you fixing the real problem? that's because you see unhashed > > kernel pointers in dmesg or is there anything else? > > In brief, the problem is that any information leak has the potential > to make exploitation easier. The changes include documentation for > the feature, where more details are provided. > I'm very skeptical that such an approach has much benefit. From the email referenced above: > I am not sure that desktop and power users would like to have their > kernel message encrypted, but there are scenarios such as in mobile > devices, where only the developers, makers of devices, may actually > benefit from access to kernel prints messages, and the users may be > more protected from exploits. Do you have any backing from makers of such devices? I'd like to hear from Google's Android team or whoever that would turn this feature on. I would be hard pressed to add such a feature if it's never used. -- Steve