linux-kernel - Re: [PATCH v2 2/4] tpm_tis: Move CRC check to generic send routine

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Date:   Wed, 07 Jun 2023 00:10:28 +0300
From:   "Jarkko Sakkinen" <jarkko@...nel.org>
To:     "Alexander Steffen" <Alexander.Steffen@...ineon.com>,
        <linux-integrity@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] tpm_tis: Move CRC check to generic send routine

On Mon Jun 5, 2023 at 8:59 PM EEST, Alexander Steffen wrote:
> The CRC functionality is initialized before tpm_tis_core, so it can be used
> on all code paths within the module. Therefore, move the CRC check to the
> generic send routine, that also contains all other checks for successful
> command transmission, so that all those checks are in one place.
>
> Also, this ensures that tpm_tis_ready is called when a CRC failure is
> detected, to clear the invalid data from the TPM, which did not happen
> previously.
>
> Signed-off-by: Alexander Steffen <Alexander.Steffen@...ineon.com>
> ---
>  drivers/char/tpm/tpm_tis_core.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index aaaa136044ae..5ddaf24518be 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -466,6 +466,12 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
>  		goto out_err;
>  	}
>  
> +	rc = tpm_tis_verify_crc(priv, len, buf);
> +	if (rc < 0) {
> +		dev_err(&chip->dev, "CRC mismatch for command.\n");
> +		goto out_err;
> +	}
> +
>  	return 0;
>  
>  out_err:
> @@ -510,12 +516,6 @@ static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
>  	if (rc < 0)
>  		return rc;
>  
> -	rc = tpm_tis_verify_crc(priv, len, buf);
> -	if (rc < 0) {
> -		dev_err(&chip->dev, "CRC mismatch for command.\n");
> -		return rc;
> -	}
> -
>  	/* go and do it */
>  	rc = tpm_tis_write8(priv, TPM_STS(priv->locality), TPM_STS_GO);
>  	if (rc < 0)
> -- 
> 2.34.1

Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>

BR, Jarkko