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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 3F2B6C4BA12 for ; Wed, 26 Feb 2020 15:15:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1AA342467D for ; Wed, 26 Feb 2020 15:15:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727265AbgBZPPR (ORCPT ); Wed, 26 Feb 2020 10:15:17 -0500 Received: from mga01.intel.com ([192.55.52.88]:20755 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726148AbgBZPPR (ORCPT ); Wed, 26 Feb 2020 10:15:17 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Feb 2020 07:15:16 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,488,1574150400"; d="scan'208";a="384831657" Received: from avgorshk-mobl.ccr.corp.intel.com (HELO localhost) ([10.252.15.208]) by orsmga004.jf.intel.com with ESMTP; 26 Feb 2020 07:15:13 -0800 Date: Wed, 26 Feb 2020 17:15:12 +0200 From: Jarkko Sakkinen To: James Bottomley Cc: linux-integrity@vger.kernel.org, Mimi Zohar , David Woodhouse , keyrings@vger.kernel.org Subject: Re: [PATCH v5 3/6] security: keys: trusted fix tpm2 authorizations Message-ID: <20200226151512.GF3407@linux.intel.com> References: <20200130101812.6271-1-James.Bottomley@HansenPartnership.com> <20200130101812.6271-4-James.Bottomley@HansenPartnership.com> <20200225164850.GB15662@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200225164850.GB15662@linux.intel.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, Feb 25, 2020 at 06:48:50PM +0200, Jarkko Sakkinen wrote: > On Thu, Jan 30, 2020 at 11:18:09AM +0100, 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 we will accept both the old hex sha1 form as well as a new > > directly supplied password: > > > > keyctl add trusted kmk "new 32 blobauth=hello keyhandle=81000001" > > > > Since a sha1 hex code must be exactly 40 bytes long and a direct > > password must be 20 or less, we use the length as the discriminator > > for which form is input. > > > > 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. > > > > Signed-off-by: James Bottomley > > Should have a fixes tag. > > > --- > > include/keys/trusted-type.h | 1 + > > security/keys/trusted-keys/trusted_tpm1.c | 26 +++++++++++++++++++++----- > > security/keys/trusted-keys/trusted_tpm2.c | 10 ++++++---- > > 3 files changed, 28 insertions(+), 9 deletions(-) > > > > diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h > > index a94c03a61d8f..b2ed3481c6a0 100644 > > --- a/include/keys/trusted-type.h > > +++ b/include/keys/trusted-type.h > > @@ -30,6 +30,7 @@ struct trusted_key_options { > > uint16_t keytype; > > uint32_t keyhandle; > > unsigned char keyauth[TPM_DIGEST_SIZE]; > > + uint32_t blobauth_len; > > unsigned char blobauth[TPM_DIGEST_SIZE]; > > uint32_t pcrinfo_len; > > unsigned char pcrinfo[MAX_PCRINFO_SIZE]; > > diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c > > index d2c5ec1e040b..3f33d3f74d3c 100644 > > --- a/security/keys/trusted-keys/trusted_tpm1.c > > +++ b/security/keys/trusted-keys/trusted_tpm1.c > > @@ -781,12 +781,28 @@ static int getoptions(char *c, struct trusted_key_payload *pay, > > return -EINVAL; > > break; > > case Opt_blobauth: > > - if (strlen(args[0].from) != 2 * SHA1_DIGEST_SIZE) > > - return -EINVAL; > > - res = hex2bin(opt->blobauth, args[0].from, > > - SHA1_DIGEST_SIZE); > > - if (res < 0) > > + /* > > + * TPM 1.2 authorizations are sha1 hashes > > + * passed in as hex strings. TPM 2.0 > > + * authorizations are simple passwords > > + * (although it can take a hash as well) > > Justify to the 80 character line length. > > > + */ > > + opt->blobauth_len = strlen(args[0].from); > > + if (opt->blobauth_len == 2 * TPM_DIGEST_SIZE) { > > + res = hex2bin(opt->blobauth, args[0].from, > > + TPM_DIGEST_SIZE); > > + if (res < 0) > > + return -EINVAL; > > + > > + opt->blobauth_len = TPM_DIGEST_SIZE; > > + } else if (tpm2 && > > + opt->blobauth_len <= sizeof(opt->blobauth)) { > > + memcpy(opt->blobauth, args[0].from, > > + opt->blobauth_len); > > + } else { > > return -EINVAL; > > + } > > This starts to be unnecessarily complicated. > > This is what I would suggest: > > opt->blobauth_len = strlen(args[0].from); > if (opt->blobauth_len == 2 * TPM_DIGEST_SIZE) { > res = hex2bin(opt->blobauth, args[0].from, > TPM_DIGEST_SIZE); > if (res < 0) > return -EINVAL; > > opt->blobauth_len = TPM_DIGEST_SIZE; > return 0; > } > > if (tpm2 && opt->blobauth_len <= sizeof(opt->blobauth)) { > memcpy(opt->blobauth, args[0].from, > opt->blobauth_len); > return 0; > } > > return -EINVAL; > > Easier to see quickly "when happens what". > > /Jarkko And in short summary "TPM2" instead of tpm2. /Jarkko