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=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 40372C4743C for ; Wed, 23 Jun 2021 08:50:37 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C4E3561166 for ; Wed, 23 Jun 2021 08:50:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C4E3561166 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:59748 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lvyah-00030B-Nv for qemu-devel@archiver.kernel.org; Wed, 23 Jun 2021 04:50:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40768) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lvyZu-0002Fv-9k for qemu-devel@nongnu.org; Wed, 23 Jun 2021 04:49:46 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:35830) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lvyZs-00082O-BO for qemu-devel@nongnu.org; Wed, 23 Jun 2021 04:49:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1624438181; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=O7Vzl1/2AMszRF0+cE018vQFKxwR1EsoIapE9ZIhpAE=; b=DXrKL/rxQl6nGSdL8nqtFAYxYe/LLls0y822ZJRnDKanA+Wgoi7Ey5D8Hl0SPEiSJpgt+Y HOLKR9NCMIco4a82Mc0kqvVqy2DYFVmCPER7Wr1vEvJ4lIp4kbUm2pzSj54jOHceL+g7Cv A6sEAp21MhfvhSxUJqnz7pmuT8xVwgI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-270-ToSDKFP3MsuQpK4Wyw68dg-1; Wed, 23 Jun 2021 04:49:28 -0400 X-MC-Unique: ToSDKFP3MsuQpK4Wyw68dg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DB338102C8CB; Wed, 23 Jun 2021 08:49:16 +0000 (UTC) Received: from redhat.com (ovpn-114-176.ams2.redhat.com [10.36.114.176]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A413860854; Wed, 23 Jun 2021 08:49:12 +0000 (UTC) Date: Wed, 23 Jun 2021 09:49:09 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Dov Murik Subject: Re: [PATCH v2 1/2] sev/i386: Introduce sev_add_kernel_loader_hashes for measured linux boot Message-ID: References: <20210621190553.1763020-1-dovmurik@linux.ibm.com> <20210621190553.1763020-2-dovmurik@linux.ibm.com> <36ff1adc-79c5-5526-2212-0aa28283fd75@linux.ibm.com> MIME-Version: 1.0 In-Reply-To: <36ff1adc-79c5-5526-2212-0aa28283fd75@linux.ibm.com> User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.223, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Tom Lendacky , Ashish Kalra , Brijesh Singh , Eduardo Habkost , "Michael S. Tsirkin" , Connor Kuehl , Laszlo Ersek , James Bottomley , Richard Henderson , qemu-devel@nongnu.org, "Dr. David Alan Gilbert" , Tobin Feldman-Fitzthum , Jim Cadden , Paolo Bonzini , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jun 23, 2021 at 11:41:56AM +0300, Dov Murik wrote: > Hi Connor, > > +cc: Daniel > > On 23/06/2021 0:15, Connor Kuehl wrote: > > On 6/21/21 2:05 PM, Dov Murik wrote: > >> +static void fill_sev_hash_table_entry(SevHashTableEntry *e, const uint8_t *guid, > >> + const uint8_t *hash, size_t hash_len) > >> +{ > >> + memcpy(e->guid, guid, sizeof(e->guid)); > >> + e->len = sizeof(*e); > >> + memcpy(e->hash, hash, hash_len); > > > > Should this memcpy be constrained to MIN(sizeof(e->hash), hash_len)? Or > > perhaps an assert statement since I see below that this function's > > caller sets this to HASH_SIZE which is currently == sizeof(e->hash). > > > > Actually, the assert statement would be easier to debug if the input > > to this function is ever unexpected, especially since it avoids an > > outcome where the input is silently truncated; which is a pitfall that > > that the memcpy clamping would fall into. > > I agree. I'll change it to: > > assert(hash_len == sizeof(e->hash)); > memcpy(e->hash, hash, sizeof(e->hash)); > > This way also the memcpy length is known at compile-time. > > > > Related: I wondered if I could replace HASH_SIZE in: > > > /* hard code sha256 digest size */ > #define HASH_SIZE 32 > > typedef struct QEMU_PACKED SevHashTableEntry { > QemuUUID guid; > uint16_t len; > uint8_t hash[HASH_SIZE]; > } SevHashTableEntry; > > > with some SHA256-related constant from crypto/hash.h, but I only found > the qcrypto_hash_digest_len(QCRYPTO_HASH_ALG_SHA256) function which > doesn't work for setting sizes of arrays at compile-time. > > Daniel: do you know what would be the proper way? We don't have any public constants right now - they're just hardcoded in hash.c struct. We could define public constants, and use those in the struct instead, as well as in other callers. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|