linux-kernel - Re: [PATCH v3 7/8] ima: Calculate and extend PCR with digests in ima_template

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Date:   Mon, 02 Mar 2020 23:03:42 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Roberto Sassu <roberto.sassu@...wei.com>,
        James.Bottomley@...senPartnership.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 7/8] ima: Calculate and extend PCR with digests in
 ima_template_entry

On Mon, 2020-02-10 at 11:04 +0100, Roberto Sassu wrote:

> @@ -219,6 +214,8 @@ int ima_restore_measurement_entry(struct ima_template_entry *entry)
>  
>  int __init ima_init_digests(void)
>  {
> +	u16 digest_size;
> +	u16 crypto_id;
>  	int i;
>  
>  	if (!ima_tpm_chip)
> @@ -229,8 +226,17 @@ int __init ima_init_digests(void)
>  	if (!digests)
>  		return -ENOMEM;
>  
> -	for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++)
> +	for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) {
>  		digests[i].alg_id = ima_tpm_chip->allocated_banks[i].alg_id;
> +		digest_size = ima_tpm_chip->allocated_banks[i].digest_size;
> +		crypto_id = ima_tpm_chip->allocated_banks[i].crypto_id;
> +
> +		/* for unmapped TPM algorithms digest is still a padded SHA1 */
> +		if (crypto_id == HASH_ALGO__LAST)
> +			digest_size = SHA1_DIGEST_SIZE;
> +
> +		memset(digests[i].digest, 0xff, digest_size);

Shouldn't the memset here be of the actual digest size even for
unmapped TPM algorithms.

> +	}
>  
>  	return 0;
>  }