linux-kernel - Re: [PATCH v4 2/4] tpm: migrate tpm2_probe() to use struct tpm

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Message-Id: <8c7f20fd-4b4f-0f25-35a4-eb1a615f1615@linux.vnet.ibm.com>
Date:   Fri, 18 May 2018 12:01:07 +0530
From:   Nayna Jain <nayna@...ux.vnet.ibm.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        linux-integrity@...r.kernel.org
Cc:     linux-security-module@...r.kernel.org,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/4] tpm: migrate tpm2_probe() to use struct tpm_buf



On 03/26/2018 05:44 PM, Jarkko Sakkinen wrote:
> In order to make struct tpm_buf the first class object for constructing TPM
> commands, migrate tpm2_probe() to use it.
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> Acked-by: Jay Freyensee <why2jjj.linux@...il.com>

Reviewed-by: Nayna Jain<nayna@...ux.vnet.ibm.com>
Tested-by: Nayna Jain<nayna@...ux.vnet.ibm.com>


Thanks & Regards,
     - Nayna

> ---
>   drivers/char/tpm/tpm2-cmd.c | 37 +++++++++++++++++++++----------------
>   1 file changed, 21 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index 7665661d9230..7bffd0fd1dca 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -844,30 +844,35 @@ static int tpm2_do_selftest(struct tpm_chip *chip)
>
>   /**
>    * tpm2_probe() - probe TPM 2.0
> - * @chip: TPM chip to use
> + * @chip: a TPM chip to probe
>    *
> - * Return: < 0 error and 0 on success.
> + * Return: 0 on success,
> + *         -errno otherwise
>    *
> - * Send idempotent TPM 2.0 command and see whether TPM 2.0 chip replied based on
> - * the reply tag.
> + * Send an idempotent TPM 2.0 command and see whether there is TPM2 chip in the
> + * other end based on the response tag. The flag TPM_CHIP_FLAG_TPM2 is set if
> + * this is the case.
>    */
>   int tpm2_probe(struct tpm_chip *chip)
>   {
> -	struct tpm2_cmd cmd;
> +	struct tpm_output_header *out;
> +	struct tpm_buf buf;
>   	int rc;
>
> -	cmd.header.in = tpm2_get_tpm_pt_header;
> -	cmd.params.get_tpm_pt_in.cap_id = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES);
> -	cmd.params.get_tpm_pt_in.property_id = cpu_to_be32(0x100);
> -	cmd.params.get_tpm_pt_in.property_cnt = cpu_to_be32(1);
> -
> -	rc = tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd), 0, 0, NULL);
> -	if (rc <  0)
> +	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
> +	if (rc)
>   		return rc;
> -
> -	if (be16_to_cpu(cmd.header.out.tag) == TPM2_ST_NO_SESSIONS)
> -		chip->flags |= TPM_CHIP_FLAG_TPM2;
> -
> +	tpm_buf_append_u32(&buf, TPM2_CAP_TPM_PROPERTIES);
> +	tpm_buf_append_u32(&buf, TPM_PT_TOTAL_COMMANDS);
> +	tpm_buf_append_u32(&buf, 1);
> +	rc = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE, 0, 0, NULL);
> +	/* We ignore TPM return codes on purpose. */
> +	if (rc >=  0) {
> +		out = (struct tpm_output_header *)buf.data;
> +		if (be16_to_cpu(out->tag) == TPM2_ST_NO_SESSIONS)
> +			chip->flags |= TPM_CHIP_FLAG_TPM2;
> +	}
> +	tpm_buf_destroy(&buf);
>   	return 0;
>   }
>   EXPORT_SYMBOL_GPL(tpm2_probe);