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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 8CE2CC43140 for ; Wed, 20 Jun 2018 22:30:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2878E20652 for ; Wed, 20 Jun 2018 22:30:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=tobin.cc header.i=@tobin.cc header.b="e9089IAn"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="IUpEq+GH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2878E20652 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=tobin.cc Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933773AbeFTWaW (ORCPT ); Wed, 20 Jun 2018 18:30:22 -0400 Received: from out2-smtp.messagingengine.com ([66.111.4.26]:37235 "EHLO out2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933528AbeFTWaV (ORCPT ); Wed, 20 Jun 2018 18:30:21 -0400 Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by mailout.nyi.internal (Postfix) with ESMTP id 5EBC221D7B; Wed, 20 Jun 2018 18:30:18 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute5.internal (MEProxy); Wed, 20 Jun 2018 18:30:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tobin.cc; h=cc :content-type:date:from:in-reply-to:message-id:mime-version :references:subject:to:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; bh=6NOdBvEcCWNnlMA4wBVywo3zt39RPJlVj3Sh6y0Dklg=; b=e9089IAn 5RAuoPRKEOQ559UVV3i6YOqxiu8yuDwbEJVZ6T4S+vkM3XkzwyzK/+8mwGM2buDG yfetH1wMSVMoIO4x4X5wf+IuYYKOFhxGIrj9GlwnaoU1s7nUHmj1xs9uGQJrpArH Yb4Nt49ALQSn0urNGigyPQU8FCl5h4bsAYT1YV+VrYr/0OSGan4fGQxfYMH8oatF 1pXGA93OgKJjG8piu+3iqQj59iutn94hrJDLLmb9ytjYgiOhB3n49r5RIlWJuIxH xxVaE6yGoWeP9Kfkab5IbP3HOaeLiGaXbCDfJFMZPNyN3DNVjc3Hg45mhHhPhKeB qtlqCKZX935mAA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-sender :x-me-sender:x-sasl-enc; s=fm3; bh=6NOdBvEcCWNnlMA4wBVywo3zt39RP JlVj3Sh6y0Dklg=; b=IUpEq+GHO8yuDLokBLpKf/bTuddyCYOgvIlAlUFZDh3mh kVQa6o/QvKAIOfdYlYNM6pjyIpdV2Ymi8zLXH33RgAN/In5po3AgNH2mwWRRpfir 7E21ibPn1buW7ivR2jglxXbQXw2+Scmudgt+ruAI1qNVvtjxb6m0nIYCDO6AQ7k4 mYIcnRfh705BGIHiJlepgpntq9navvshYD92Yd5FuONUclYVrn2aRNOxxv5Mfnw/ Hbp5gqqC6A0qrcPqY73GeGT7+3xVSEOIyLTuxhdVq14iFvM5RsRMMQ77DG1myW69 ZqpTYZ2zZrgEW8uhud8va2oIg3k3UbVCFZ1t1YIEQ== X-ME-Proxy: X-ME-Sender: Received: from localhost (124-171-16-226.dyn.iinet.net.au [124.171.16.226]) by mail.messagingengine.com (Postfix) with ESMTPA id 69F13E4445; Wed, 20 Jun 2018 18:30:17 -0400 (EDT) Date: Thu, 21 Jun 2018 08:30:14 +1000 From: "Tobin C. Harding" To: Randy Dunlap Cc: Theodore Ts'o , Linus Torvalds , Steven Rostedt , Kees Cook , Anna-Maria Gleixner , Andrew Morton , Greg Kroah-Hartman , Arnd Bergmann , Andy Shevchenko , linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 4/4] vsprintf: Add command line option debug_boot_weak_hash Message-ID: <20180620223014.GE11671@eros> References: <20180620042046.30806-1-me@tobin.cc> <20180620042046.30806-5-me@tobin.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Mailer: Mutt 1.9.4 (2018-02-28) User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 20, 2018 at 09:09:49AM -0700, Randy Dunlap wrote: > On 06/19/2018 09:20 PM, Tobin C. Harding wrote: > > Currently printing [hashed] pointers requires enough entropy to be > > available. Early in the boot sequence this may not be the case > > resulting in a dummy string '(____ptrval____)' being printed. This > > makes debugging the early boot sequence difficult. We can relax the > > requirement to use cryptographically secure hashing during debugging. > > This enables debugging while keeping development/production kernel > > behaviour the same. > > > > If new command line option debug_boot_weak_hash is enabled use > > cryptographically insecure hashing and hash pointer value immediately. > > > > Signed-off-by: Tobin C. Harding > > Reviewed-by: Steven Rostedt (VMware) > > --- > > Documentation/admin-guide/kernel-parameters.txt | 9 +++++++++ > > lib/vsprintf.c | 17 +++++++++++++++++ > > 2 files changed, 26 insertions(+) > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > > index 638342d0a095..a116fc0366b0 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -748,6 +748,15 @@ > > > > debug [KNL] Enable kernel debugging (events log level). > > > > + debug_boot_weak_hash > > + [KNL] Enable printing pointers early in the boot > > + sequence. If enabled, we use a weak hash instead of > > + siphash to hash pointers. Use this option if you need > > + to see pointer values during early boot (i.e you are > > maybe: > to see hashed pointer values > i.e., not raw pointers. You cannot see 'raw pointers' anyways? > > > + seeing instances of '(___ptrval___)'). > > + Cryptographically insecure, please do not use on > > + production kernels. thanks for the review, I don't quiet see how to use your suggestion to make the text clearer. If you still feel this change is needed perhaps you could write so I understand i.e 'Use this option if ...' thanks, Tobin.