From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Sakkinen Date: Mon, 06 Jan 2020 21:48:07 +0000 Subject: Re: [PATCH v4 3/9] security: keys: trusted fix tpm2 authorizations Message-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable List-Id: References: <20191230173802.8731-1-James.Bottomley@HansenPartnership.com> <20191230173802.8731-4-James.Bottomley@HansenPartnership.com> In-Reply-To: To: James Bottomley , linux-integrity@vger.kernel.org Cc: Mimi Zohar , David Woodhouse , keyrings@vger.kernel.org On Mon, 2020-01-06 at 23:45 +0200, Jarkko Sakkinen wrote: > On Mon, 2019-12-30 at 09:37 -0800, James Bottomley wrote: > > In TPM 1.2 an authorization was a 20 byte number. The spec actually > > recommended you to hash variable length passwords and use the sha1 > > hash as the authorization. Because the spec doesn't require this > > hashing, the current authorization for trusted keys is a 40 digit hex > > number. For TPM 2.0 the spec allows the passing in of variable length > > passwords and passphrases directly, so we should allow that in trusted > > keys for ease of use. Update the 'blobauth' parameter to take this > > into account, so we can now use plain text passwords for the keys. > >=20 > > so before > >=20 > > keyctl add trusted kmk "new 32 blobauth=F572d396fae9206628714fb2ce00f72= e94f2258f" > >=20 > > after: > >=20 > > keyctl add trusted kmk "new 32 blobauth=3Dhello keyhandle=81000001" > >=20 > > Note this is both and enhancement and a potential bug fix. The TPM > > 2.0 spec requires us to strip leading zeros, meaning empyty > > authorization is a zero length HMAC whereas we're currently passing in > > 20 bytes of zeros. A lot of TPMs simply accept this as OK, but the > > Microsoft TPM emulator rejects it with TPM_RC_BAD_AUTH, so this patch > > makes the Microsoft TPM emulator work with trusted keys. >=20 > Even if for good reasons, you should be explicit when you make an API > change that is not backwards compatible. Also you have illformed abbrevation in your short summary. Should be TPM2, not tpm2. /Jarkko 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=-0.8 required=3.0 tests=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 2EF4AC33C8C for ; Mon, 6 Jan 2020 21:48:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 020F3207FF for ; Mon, 6 Jan 2020 21:48:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726713AbgAFVsL (ORCPT ); Mon, 6 Jan 2020 16:48:11 -0500 Received: from mga06.intel.com ([134.134.136.31]:22927 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726695AbgAFVsL (ORCPT ); Mon, 6 Jan 2020 16:48:11 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Jan 2020 13:48:10 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,403,1571727600"; d="scan'208";a="215324277" Received: from ryanchev-mobl.ger.corp.intel.com ([10.252.23.147]) by orsmga008.jf.intel.com with ESMTP; 06 Jan 2020 13:48:08 -0800 Message-ID: Subject: Re: [PATCH v4 3/9] security: keys: trusted fix tpm2 authorizations From: Jarkko Sakkinen To: James Bottomley , linux-integrity@vger.kernel.org Cc: Mimi Zohar , David Woodhouse , keyrings@vger.kernel.org Date: Mon, 06 Jan 2020 23:48:07 +0200 In-Reply-To: References: <20191230173802.8731-1-James.Bottomley@HansenPartnership.com> <20191230173802.8731-4-James.Bottomley@HansenPartnership.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.1-2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Mon, 2020-01-06 at 23:45 +0200, Jarkko Sakkinen wrote: > On Mon, 2019-12-30 at 09:37 -0800, James Bottomley wrote: > > In TPM 1.2 an authorization was a 20 byte number. The spec actually > > recommended you to hash variable length passwords and use the sha1 > > hash as the authorization. Because the spec doesn't require this > > hashing, the current authorization for trusted keys is a 40 digit hex > > number. For TPM 2.0 the spec allows the passing in of variable length > > passwords and passphrases directly, so we should allow that in trusted > > keys for ease of use. Update the 'blobauth' parameter to take this > > into account, so we can now use plain text passwords for the keys. > > > > so before > > > > keyctl add trusted kmk "new 32 blobauth=f572d396fae9206628714fb2ce00f72e94f2258f" > > > > after: > > > > keyctl add trusted kmk "new 32 blobauth=hello keyhandle=81000001" > > > > Note this is both and enhancement and a potential bug fix. The TPM > > 2.0 spec requires us to strip leading zeros, meaning empyty > > authorization is a zero length HMAC whereas we're currently passing in > > 20 bytes of zeros. A lot of TPMs simply accept this as OK, but the > > Microsoft TPM emulator rejects it with TPM_RC_BAD_AUTH, so this patch > > makes the Microsoft TPM emulator work with trusted keys. > > Even if for good reasons, you should be explicit when you make an API > change that is not backwards compatible. Also you have illformed abbrevation in your short summary. Should be TPM2, not tpm2. /Jarkko