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=-2.2 required=3.0 tests=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 D786CC4360D for ; Wed, 25 Sep 2019 12:34:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B79BB21655 for ; Wed, 25 Sep 2019 12:34:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729470AbfIYMeG (ORCPT ); Wed, 25 Sep 2019 08:34:06 -0400 Received: from mga01.intel.com ([192.55.52.88]:51738 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726369AbfIYMeG (ORCPT ); Wed, 25 Sep 2019 08:34:06 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Sep 2019 05:34:05 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,548,1559545200"; d="scan'208";a="364310624" Received: from kmakows-mobl.ger.corp.intel.com (HELO localhost) ([10.249.39.225]) by orsmga005.jf.intel.com with ESMTP; 25 Sep 2019 05:34:02 -0700 Date: Wed, 25 Sep 2019 15:34:01 +0300 From: Jarkko Sakkinen To: James Bottomley Cc: linux-integrity@vger.kernel.org, linux-crypto@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [PATCH v6 02/12] tpm-buf: add handling for TPM2B types Message-ID: <20190925123401.GA24028@linux.intel.com> References: <1568031408.6613.29.camel@HansenPartnership.com> <1568031515.6613.31.camel@HansenPartnership.com> <20190920141826.GC9578@linux.intel.com> <1569323560.24519.6.camel@HansenPartnership.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1569323560.24519.6.camel@HansenPartnership.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Tue, Sep 24, 2019 at 07:12:40AM -0400, James Bottomley wrote: > I thought about that. The main problem is that most of the > construct/append functions use the header, and these are the functions > most useful to the TPM2B operation. > > The other thing that argues against this is that the TPM2B case would > save nothing if we eliminated the header, because we allocate a page > for all the data regardless. It would be way more clean. There is absolutely nothing TPM2B specific. > > and also it makes sense to have a separate length field in the > > struct to keep the code sane given that sometimes the buffer does not > > store the length. > > I'm really not sure about that one. The header length has to be filled > in for the non-TPM2B case but right at the moment we have no finish > function for the buf where it could be, so we'd end up having to > maintain two lengths in every update operation on non-TPM2B buffers. > That seems inefficient and the only slight efficiency we get in the > TPM2B case is not having to do the big endian conversion from the > header which doesn't seem to be worth the added complexity. It would be way more clean and an insignificant concern when it comes to performance. I don't see any problem updating two lengths. /Jarkko