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From: Mimi Zohar <zohar@linux.vnet.ibm.com>
To: Ken Goldman <kgold@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	tpmdd-devel@lists.sourceforge.net, keyrings@vger.kernel.org,
	linux-ima-devel@lists.sourceforge.net
Subject: Re: [tpmdd-devel] [Linux-ima-devel] [PATCH v3 0/6] Updated API for TPM 2.0 PCR extend
Date: Wed, 05 Jul 2017 12:06:42 -0400	[thread overview]
Message-ID: <1499270802.3059.101.camel@linux.vnet.ibm.com> (raw)
In-Reply-To: <55cf0a07-bee8-a034-4d40-6232bc0eefb8@linux.vnet.ibm.com>

On Wed, 2017-07-05 at 11:18 -0400, Ken Goldman wrote:
> On 6/28/2017 1:28 PM, Jarkko Sakkinen wrote:
>  > On Mon, Jun 26, 2017 at 08:33:59AM -0400, Mimi Zohar wrote:
>  >> On Sat, 2017-06-24 at 11:03 +0200, Jarkko Sakkinen wrote:
>  >>> On Wed, Jun 21, 2017 at 04:29:35PM +0200, Roberto Sassu wrote:

>  >>> There's absolutely no need to pass digest size like you do BTW as 
> it >>> is defined by the standard.
>  >>
>  >> For algorithms known to the crypto subsystem, that is fine, but for
>  >> the unknown TPM crypto algorithms, we would need to somehow query the
>  >> TPM for the digest sizes to create the mapping.
>  >>
>  >> Mimi
>  >
>  > There's a TPM command to query TPM algorithms.
> 
> This is true - one getcap to determine the number of algorithms, then a 
> pcr read, then parse the response structures and match the algorithms to 
> sizes.
> 
> Alternatively, could you create a table mapping the algorithm to the 
> size?  There are currently 8 approved algorithms, meaning the table is 
> 32 bytes, probably less code than the queries.
> 
> As for an algorithm appearing in the TPM that's not in the table, it 
> takes a year or more for a new algorithm to appear.  Is that enough time 
> to patch the device driver?
> 
> FYI, the 8 algorithms are:
> 
> sha1, sha256, sha384, sha512, sm3-256, sha3-256, sha3-384, sha3-512.
> 
> I am only aware of sha1, sha256, and sm3-256 being used in production 
> hardware TPMs.

New devices aren't being shipped with the most recent kernels.  So
even if the upstream kernel supports the newer crypto algorithms, that
doesn't imply that it is available.

A safer method would be to query the TPM for the digest sizes.

Mimi

      reply	other threads:[~2017-07-05 16:06 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-21 14:29 [PATCH v3 0/6] Updated API for TPM 2.0 PCR extend Roberto Sassu
2017-06-21 14:29 ` [PATCH v3 4/6] tpm: replace TPM algorithms IDs with tpm_pcr_bank_info structs in tpm_chip Roberto Sassu
2017-06-23 10:32   ` Jarkko Sakkinen
2017-06-21 14:29 ` [PATCH v3 5/6] tpm: introduce tpm_get_pcr_banks_info() Roberto Sassu
2017-06-23 10:35   ` Jarkko Sakkinen
2017-06-21 14:29 ` [PATCH v3 6/6] tpm: pass multiple digests to tpm_pcr_extend() Roberto Sassu
     [not found]   ` <20170621142941.32674-7-roberto.sassu-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2017-06-23 10:37     ` Jarkko Sakkinen
     [not found] ` <20170621142941.32674-1-roberto.sassu-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2017-06-21 14:29   ` [PATCH v3 1/6] tpm: use tpm_buf functions to perform a PCR read Roberto Sassu
2017-06-22 10:14     ` [tpmdd-devel] " Jarkko Sakkinen
     [not found]       ` <20170622101404.blfpqcryrbe35ha4-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-06-22 11:54         ` Roberto Sassu
2017-06-23 10:56           ` [tpmdd-devel] " Jarkko Sakkinen
2017-06-21 14:29   ` [PATCH v3 2/6] tpm: use tpm2_pcr_read_tpm_buf() in tpm2_do_selftest() Roberto Sassu
2017-06-23  9:55     ` [tpmdd-devel] " Jarkko Sakkinen
2017-06-23 10:22       ` Roberto Sassu
2017-06-21 14:29   ` [PATCH v3 3/6] tpm: introduce tpm_pcr_bank_info structure with digest_size from TPM Roberto Sassu
2017-06-23 10:26     ` Jarkko Sakkinen
     [not found]       ` <20170623102606.3xkuqbslr3g3o22s-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-06-23 11:25         ` Roberto Sassu
     [not found]     ` <20170621142941.32674-4-roberto.sassu-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2017-06-27 15:24       ` Mimi Zohar
2017-06-24  9:03   ` [PATCH v3 0/6] Updated API for TPM 2.0 PCR extend Jarkko Sakkinen
     [not found]     ` <20170624090325.kbqhwkrx5qvtxveg-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-06-26  6:58       ` Roberto Sassu
2017-06-26  7:21       ` Roberto Sassu
2017-06-28 17:10         ` Jarkko Sakkinen
2017-06-26 12:33     ` [Linux-ima-devel] " Mimi Zohar
2017-06-26 14:56       ` Roberto Sassu
2017-06-26 17:12         ` Mimi Zohar
2017-06-28 17:28       ` Jarkko Sakkinen
2017-06-28 22:28         ` Mimi Zohar
2017-07-05 15:18         ` [tpmdd-devel] " Ken Goldman
2017-07-05 16:06           ` Mimi Zohar [this message]

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