From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Date: Wed, 16 Sep 2020 19:52:14 +0000 Subject: Re: [PATCH v11 3/5] security: keys: trusted: fix TPM2 authorizations Message-Id: <1600285934.7475.19.camel@HansenPartnership.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable List-Id: References: <20200912172643.9063-1-James.Bottomley@HansenPartnership.com> <20200912172643.9063-4-James.Bottomley@HansenPartnership.com> <20200915090950.GB3612@linux.intel.com> In-Reply-To: <20200915090950.GB3612@linux.intel.com> To: Jarkko Sakkinen Cc: linux-integrity@vger.kernel.org, Mimi Zohar , David Woodhouse , keyrings@vger.kernel.org, David Howells On Tue, 2020-09-15 at 12:09 +0300, Jarkko Sakkinen wrote: > On Sat, Sep 12, 2020 at 10:26:41AM -0700, 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=F572d396fae9206628714fb2ce00f72e94f2258f" > >=20 > > after we will accept both the old hex sha1 form as well as a new > > directly supplied password: > >=20 > > keyctl add trusted kmk "new 32 blobauth=3Dhello keyhandle=81000001" > >=20 > > 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. > >=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 > > Fixes: 0fe5480303a1 ("keys, trusted: seal/unseal with TPM 2.0 > > chips") > > Signed-off-by: James Bottomley > > > > Reviewed-by: Jarkko Sakkinen >=20 > I created a key: >=20 > $ sudo ./tpm2-root-key > 0x80000000 > $ sudo ./tpm2-list-handles > 0x80000000 > $ keyctl add trusted kmk "new 32 blobauth=3Dhello keyhandle=3D0x80000000" > Well, you're getting that because the command isn't complete ... you need a keyring specifier at the end, like @u. However, even with that there's a bug in the code that would cause this to return EINVAL: the blobauth handler has a return 0 where it should have a break ... I think that happened as a result of the v6 rework which split up the if ... else if ... else chain. The result is the processing of options terminates at blobauth, so if it's last, as I've been testing with, everything is fine. If it's first as you specify, none of the options following the blobauth get processed. I'll fix this up and add an @u to the commit message. James 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=-8.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 67D78C433E2 for ; Wed, 16 Sep 2020 19:52:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 02AF421582 for ; Wed, 16 Sep 2020 19:52:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="LpGstKQB"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="LpGstKQB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727864AbgIPTw3 (ORCPT ); Wed, 16 Sep 2020 15:52:29 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:55536 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727745AbgIPTwU (ORCPT ); Wed, 16 Sep 2020 15:52:20 -0400 Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 400A08EE7B7; Wed, 16 Sep 2020 12:52:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1600285936; bh=CM5FFtoiUXeFDS04HDTOcYoUbEJiATN117O4vHwx2oo=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=LpGstKQBeDnpBUf59CwzaJlszBaCFr1PtqY/G//bx/zEUnl02pqVCM+6heHLIjvbU gTcvpn+Bg9XqtKD8FFvpEXUt+j1zszj3lkFa2o3sFMFfWHGLLo6hRvNRpkk2eee1EZ PSsRr3XDJuiSaGSgpflN+UVQB9EleUirRGmlmtsA= Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id YvCNN2sTluOY; Wed, 16 Sep 2020 12:52:16 -0700 (PDT) Received: from [153.66.254.174] (c-73-35-198-56.hsd1.wa.comcast.net [73.35.198.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id ACA828EE792; Wed, 16 Sep 2020 12:52:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1600285936; bh=CM5FFtoiUXeFDS04HDTOcYoUbEJiATN117O4vHwx2oo=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=LpGstKQBeDnpBUf59CwzaJlszBaCFr1PtqY/G//bx/zEUnl02pqVCM+6heHLIjvbU gTcvpn+Bg9XqtKD8FFvpEXUt+j1zszj3lkFa2o3sFMFfWHGLLo6hRvNRpkk2eee1EZ PSsRr3XDJuiSaGSgpflN+UVQB9EleUirRGmlmtsA= Message-ID: <1600285934.7475.19.camel@HansenPartnership.com> Subject: Re: [PATCH v11 3/5] security: keys: trusted: fix TPM2 authorizations From: James Bottomley To: Jarkko Sakkinen Cc: linux-integrity@vger.kernel.org, Mimi Zohar , David Woodhouse , keyrings@vger.kernel.org, David Howells Date: Wed, 16 Sep 2020 12:52:14 -0700 In-Reply-To: <20200915090950.GB3612@linux.intel.com> References: <20200912172643.9063-1-James.Bottomley@HansenPartnership.com> <20200912172643.9063-4-James.Bottomley@HansenPartnership.com> <20200915090950.GB3612@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 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 Tue, 2020-09-15 at 12:09 +0300, Jarkko Sakkinen wrote: > On Sat, Sep 12, 2020 at 10:26:41AM -0700, 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. > > > > Fixes: 0fe5480303a1 ("keys, trusted: seal/unseal with TPM 2.0 > > chips") > > Signed-off-by: James Bottomley > > > > Reviewed-by: Jarkko Sakkinen > > I created a key: > > $ sudo ./tpm2-root-key > 0x80000000 > $ sudo ./tpm2-list-handles > 0x80000000 > $ keyctl add trusted kmk "new 32 blobauth=hello keyhandle=0x80000000" > Well, you're getting that because the command isn't complete ... you need a keyring specifier at the end, like @u. However, even with that there's a bug in the code that would cause this to return EINVAL: the blobauth handler has a return 0 where it should have a break ... I think that happened as a result of the v6 rework which split up the if ... else if ... else chain. The result is the processing of options terminates at blobauth, so if it's last, as I've been testing with, everything is fine. If it's first as you specify, none of the options following the blobauth get processed. I'll fix this up and add an @u to the commit message. James