linux-kernel - Re: [PATCH v9 6/6] tpm: pass an array of tpm_extend_digest structures to tpm_pcr

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Message-ID: <20190201133949.GE17861@linux.intel.com>
Date:   Fri, 1 Feb 2019 15:39:49 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Roberto Sassu <roberto.sassu@...wei.com>
Cc:     zohar@...ux.ibm.com, david.safford@...com, monty.wiseman@...com,
        matthewgarrett@...gle.com, linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, keyrings@...r.kernel.org,
        linux-kernel@...r.kernel.org, silviu.vlasceanu@...wei.com
Subject: Re: [PATCH v9 6/6] tpm: pass an array of tpm_extend_digest
 structures to tpm_pcr_extend()

On Fri, Feb 01, 2019 at 11:06:41AM +0100, Roberto Sassu wrote:
> Currently, tpm_pcr_extend() accepts as an input only a SHA1 digest.
> 
> This patch replaces the hash parameter of tpm_pcr_extend() with an array of
> tpm_digest structures, so that the caller can provide a digest for each PCR
> bank currently allocated in the TPM.
> 
> tpm_pcr_extend() will not extend banks for which no digest was provided,
> as it happened before this patch, but instead it requires that callers
> provide the full set of digests. Since the number of digests will always be
> chip->nr_allocated_banks, the count parameter has been removed.
> 
> Due to the API change, ima_pcr_extend() and pcrlock() have been modified.
> Since the number of allocated banks is not known in advance, the memory for
> the digests must be dynamically allocated. To avoid performance degradation
> and to avoid that a PCR extend is not done due to lack of memory, the array
> of tpm_digest structures is allocated by the users of the TPM driver at
> initialization time.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>

/Jarkko