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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 2F6CCC2B9F4 for ; Mon, 28 Jun 2021 09:32:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0E6AD61C59 for ; Mon, 28 Jun 2021 09:32:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232315AbhF1Jes (ORCPT ); Mon, 28 Jun 2021 05:34:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:34710 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232152AbhF1Jer (ORCPT ); Mon, 28 Jun 2021 05:34:47 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 968D5619C5; Mon, 28 Jun 2021 09:32:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1624872742; bh=lsamg+PxzeY+uZhhCSlp8N3GB8mjamZ+vBUc2M5/IYQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UyJ9GaPwLeevhfj1fFwQA3wbu0RqZcRtqjK2xyU8GUAuPRE2DQ0WerR6AvwzpJaZs 4FvFkl0XcIQDnn9boKYDXPBNRul/IT0PuqxAXR53l+yfYs9QBQgZWHwL1GB64S2JWB MCn4MTwXS/iybIsQIU+StErstpj64CMUH/GH/RXA= Date: Mon, 28 Jun 2021 11:32:18 +0200 From: Greg KH To: Roberto Sassu Cc: "zohar@linux.ibm.com" , "linux-integrity@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [RFC][PATCH 03/12] digest_lists: Basic definitions Message-ID: References: <20210625165614.2284243-1-roberto.sassu@huawei.com> <20210625165614.2284243-4-roberto.sassu@huawei.com> <860717cce60f47abb3c9dc3c1bd32ab7@huawei.com> <4acc7e8f15834b83b310b9e2ff9ba3d2@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4acc7e8f15834b83b310b9e2ff9ba3d2@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Mon, Jun 28, 2021 at 09:27:05AM +0000, Roberto Sassu wrote: > > From: Greg KH [mailto:gregkh@linuxfoundation.org] > > Sent: Monday, June 28, 2021 10:46 AM > > On Mon, Jun 28, 2021 at 08:30:32AM +0000, Roberto Sassu wrote: > > > > > +struct compact_list_hdr { > > > > > + __u8 version; > > > > > > > > You should never need a version, that way lies madness. > > > > > > We wanted to have a way to switch to a new format, if necessary. > > > > Then just add a new ioctl if you need that in the future, no need to try > > to cram it into this one. > > Given that digest lists are generated elsewhere, it would be still > unclear when the ioctl() would be issued. Maybe the kernel needs > to parse both v1 and v2 digest lists (I expect that v1 cannot be easily > converted to v2, if they are signed). > > It would be also unpractical if digest lists are loaded at kernel > initialization time (I didn't send the patch yet). Then that is up to your api design, I do not know. But note that "version" fields almost always never work, so be careful about assuming that this will solve any future issues. > > > > > + __le16 type; > > > > > + __le16 modifiers; > > > > > + __le16 algo; > > > > > + __le32 count; > > > > > + __le32 datalen; > > > > > > > > Why are user/kernel apis specified in little endian format? Why would > > > > that matter? Shouldn't they just be "native" endian? > > > > > > I thought this would make it clear that the kernel always expects the > > > digest lists to be in little endian. > > > > Why would a big endian system expect the data from userspace to be in > > little endian? Shouldn't this always just be "native" endian given that > > this is not something that is being sent to hardware? > > The digest list might come from a system with different endianness. Ok, I have no idea what digests really are used for then. So stick with little endian and be sure to properly convert within the kernel as needed. thanks, greg k-h