linux-kernel - Re: [PATCH v3 4/5] tpm: retrieve digest size of unknown algorithms with PCR read

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Message-Id: <1541089389.4035.34.camel@linux.ibm.com>
Date:   Thu, 01 Nov 2018 12:23:09 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Roberto Sassu <roberto.sassu@...wei.com>,
        jarkko.sakkinen@...ux.intel.com
Cc:     linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, silviu.vlasceanu@...wei.com
Subject: Re: [PATCH v3 4/5] tpm: retrieve digest size of unknown algorithms
 with PCR read

On Thu, 2018-11-01 at 12:02 -0400, Mimi Zohar wrote:
> On Tue, 2018-10-30 at 16:47 +0100, Roberto Sassu wrote:

 
> > +static int tpm2_init_bank_info(struct tpm_chip *chip,
> > +			       struct tpm_bank_info *bank)
> > +{
> > +	struct tpm_digest digest = {.alg_id = bank->alg_id};
> > +	int i;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++) {
> > +		enum hash_algo crypto_algo = tpm2_hash_map[i].crypto_id;
> > +
> > +		if (bank->alg_id != tpm2_hash_map[i].tpm_id)
> > +			continue;
> > +
> > +		bank->digest_size = hash_digest_size[crypto_algo];
> > +		bank->crypto_id = crypto_algo;
> > +		return 0;
> > +	}
> > +
> > +	return tpm2_pcr_read(chip, 0, &digest, &bank->digest_size);

Somewhere there needs to be a check to verify that the returned digest
size is equal to or less than the maximum digest size defined in
tpm_digest structure.

Mimi