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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: linux-integrity@vger.kernel.org, linux-crypto@vger.kernel.org,
	linux-security-module@vger.kernel.org
Subject: Re: [PATCH v6 02/12] tpm-buf: add handling for TPM2B types
Date: Wed, 25 Sep 2019 15:34:01 +0300
Message-ID: <20190925123401.GA24028@linux.intel.com> (raw)
In-Reply-To: <1569323560.24519.6.camel@HansenPartnership.com>

On Tue, Sep 24, 2019 at 07:12:40AM -0400, James Bottomley wrote:
> I thought about that.  The main problem is that most of the
> construct/append functions use the header, and these are the functions
> most useful to the TPM2B operation.
> 
> The other thing that argues against this is that the TPM2B case would
> save nothing if we eliminated the header, because we allocate a page
> for all the data regardless.

It would be way more clean. There is absolutely nothing TPM2B specific.

> >  and also it makes sense to have a separate length field in the
> > struct to keep the code sane given that sometimes the buffer does not
> > store the length.
> 
> I'm really not sure about that one.  The header length has to be filled
> in for the non-TPM2B case but right at the moment we have no finish
> function for the buf where it could be, so we'd end up having to
> maintain two lengths in every update operation on non-TPM2B buffers. 
> That seems inefficient and the only slight efficiency we get in the
> TPM2B case is not having to do the big endian conversion from the
> header which doesn't seem to be worth the added complexity.

It would be way more clean and an insignificant concern when it comes
to performance. I don't see any problem updating two lengths.

/Jarkko

  reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-09 12:16 [PATCH v6 00/12] add integrity and security to TPM2 transactions James Bottomley
2019-09-09 12:17 ` [PATCH v6 01/12] tpm-buf: move from static inlines to real functions James Bottomley
2019-09-20 14:06   ` Jarkko Sakkinen
2019-09-20 14:06     ` Jarkko Sakkinen
2019-09-20 15:53       ` James Bottomley
2019-09-09 12:18 ` [PATCH v6 02/12] tpm-buf: add handling for TPM2B types James Bottomley
2019-09-20 14:18   ` Jarkko Sakkinen
2019-09-24 11:12     ` James Bottomley
2019-09-25 12:34       ` Jarkko Sakkinen [this message]
2019-09-25 12:34         ` Jarkko Sakkinen
2019-09-09 12:19 ` [PATCH v6 03/12] tpm-buf: add cursor based functions for response parsing James Bottomley
2019-09-09 12:19 ` [PATCH v6 04/12] tpm2-space: export the context save and load commands James Bottomley
2019-09-09 12:20 ` [PATCH v6 05/12] tpm2-sessions: Add full HMAC and encrypt/decrypt session handling James Bottomley
2019-09-20 14:34   ` Jarkko Sakkinen
2019-09-20 14:35     ` Jarkko Sakkinen
2019-09-24 11:18       ` James Bottomley
2019-09-09 12:21 ` [PATCH v6 06/12] tpm-buf: add tpm_buf_parameters() James Bottomley
2019-09-09 12:22 ` [PATCH v6 07/12] tpm2: add hmac checks to tpm2_pcr_extend() James Bottomley
2019-09-09 12:22 ` [PATCH v6 08/12] tpm2: add session encryption protection to tpm2_get_random() James Bottomley
2019-09-09 12:23 ` [PATCH v6 09/12] trusted keys: Add session encryption protection to the seal/unseal path James Bottomley
2019-09-09 12:24 ` [PATCH v6 10/12] tpm: add the null key name as a tpm2 sysfs variable James Bottomley
2019-09-09 12:25 ` [PATCH v6 11/12] Documentation: add tpm-security.rst James Bottomley
2019-09-09 12:26 ` [PATCH v6 12/12] tpm2-sessions: NOT FOR COMMITTING add sessions testing James Bottomley
2019-09-10 16:21 ` [PATCH v6 00/12] add integrity and security to TPM2 transactions Jarkko Sakkinen
2019-09-10 16:29   ` James Bottomley
2019-09-11  8:42   ` Jarkko Sakkinen
2019-09-11  9:40     ` Jarkko Sakkinen

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