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, URIBL_BLOCKED,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 80FEEC35E04 for ; Tue, 25 Feb 2020 16:48:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F7372051A for ; Tue, 25 Feb 2020 16:48:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729193AbgBYQsy (ORCPT ); Tue, 25 Feb 2020 11:48:54 -0500 Received: from mga12.intel.com ([192.55.52.136]:47869 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728200AbgBYQsx (ORCPT ); Tue, 25 Feb 2020 11:48:53 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Feb 2020 08:48:53 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,484,1574150400"; d="scan'208";a="271377075" Received: from gbwalsh-mobl6.ger.corp.intel.com (HELO localhost) ([10.252.26.72]) by fmsmga002.fm.intel.com with ESMTP; 25 Feb 2020 08:48:51 -0800 Date: Tue, 25 Feb 2020 18:48:50 +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: <20200225164850.GB15662@linux.intel.com> References: <20200130101812.6271-1-James.Bottomley@HansenPartnership.com> <20200130101812.6271-4-James.Bottomley@HansenPartnership.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200130101812.6271-4-James.Bottomley@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 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