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, URIBL_BLOCKED,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 DD7CAC433ED for ; Thu, 29 Apr 2021 20:01:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B66D9613E7 for ; Thu, 29 Apr 2021 20:01:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236979AbhD2UB4 convert rfc822-to-8bit (ORCPT ); Thu, 29 Apr 2021 16:01:56 -0400 Received: from jabberwock.ucw.cz ([46.255.230.98]:51808 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237580AbhD2UAd (ORCPT ); Thu, 29 Apr 2021 16:00:33 -0400 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 339D01C0BA4; Thu, 29 Apr 2021 21:59:45 +0200 (CEST) Date: Thu, 29 Apr 2021 21:59:44 +0200 From: Pavel Machek To: "Rafael J. Wysocki" Cc: Eric Biggers , Chris von Recklinghausen , Ard Biesheuvel , Simo Sorce , Dexuan Cui , Linux PM , Linux Crypto Mailing List , Linux Kernel Mailing List Subject: Re: [PATCH v5 1/1] use crc32 instead of md5 for hibernation e820 integrity check Message-ID: <20210429195944.GB1067@bug> References: <20210408131506.17941-1-crecklin@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Hi! > > > > Suspend fails on a system in fips mode because md5 is used for the e820 > > > > integrity check and is not available. Use crc32 instead. > > > > > > > > This patch changes the integrity check algorithm from md5 to > > > > crc32. This integrity check is used only to verify accidental > > > > corruption of the hybernation data > > > > > > It isn't used for that. > > > > > > In fact, it is used to detect differences between the memory map used > > > before hibernation and the one made available by the BIOS during the > > > subsequent resume. And the check is there, because it is generally > > > unsafe to load the hibernation image into memory if the current memory > > > map doesn't match the one used when the image was created. > > > > So what types of "differences" are you trying to detect? If you need to detect > > differences caused by someone who maliciously made changes ("malicious" implies > > they may try to avoid detection), then you need to use a cryptographic hash > > function (or a cryptographic MAC if the hash value isn't stored separately). If > > you only need to detect non-malicious changes (normally these would be called > > "accidental" changes, but sure, it could be changes that are "intentionally" > > made provided that the other side can be trusted to not try to avoid > > detection...) > > That's the case here. md5 is fine for this purpose. crc32 may be too weak. I don't see why this needs changing. Maybe fips should understand that md5 has other uses than crypto? Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html