Re: [PATCH] tpm: Add major_version sysfs file

[Mimi Zohar <zohar@linux.ibm.com>]

On Fri, 2019-10-25 at 07:28 -0700, Jerry Snitselaar wrote:
> Easily determining what TCG version a tpm device implements
> has been a pain point for userspace for a long time, so
> add a sysfs file to report the tcg version of a tpm device.

Use "TCG" uppercase consistently.
 
> 
> Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> Cc: Peter Huewe <peterhuewe@gmx.de>
> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: linux-integrity@vger.kernel.org
> Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>

thanks!

Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>

FYI, on my system(s) the new file is accessible as
/sys/class/tpm/tpm0/version_major.  Does this need to be documented
anywhere?


> ---
>  drivers/char/tpm/tpm-sysfs.c | 34 +++++++++++++++++++++++++++-------
>  1 file changed, 27 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
> index edfa89160010..9372c2d6f0b3 100644
> --- a/drivers/char/tpm/tpm-sysfs.c
> +++ b/drivers/char/tpm/tpm-sysfs.c
> @@ -309,7 +309,17 @@ static ssize_t timeouts_show(struct device *dev, struct device_attribute *attr,
>  }
>  static DEVICE_ATTR_RO(timeouts);
>  
> -static struct attribute *tpm_dev_attrs[] = {
> +static ssize_t major_version_show(struct device *dev,
> +				  struct device_attribute *attr, char *buf)
> +{
> +	struct tpm_chip *chip = to_tpm_chip(dev);
> +
> +	return sprintf(buf, "%s\n", chip->flags & TPM_CHIP_FLAG_TPM2
> +		       ? "2.0" : "1.2");
> +}
> +static DEVICE_ATTR_RO(major_version);
> +
> +static struct attribute *tpm12_dev_attrs[] = {
>  	&dev_attr_pubek.attr,
>  	&dev_attr_pcrs.attr,
>  	&dev_attr_enabled.attr,
> @@ -320,18 +330,28 @@ static struct attribute *tpm_dev_attrs[] = {
>  	&dev_attr_cancel.attr,
>  	&dev_attr_durations.attr,
>  	&dev_attr_timeouts.attr,
> +	&dev_attr_major_version.attr,
>  	NULL,
>  };
>  
> -static const struct attribute_group tpm_dev_group = {
> -	.attrs = tpm_dev_attrs,
> +static struct attribute *tpm20_dev_attrs[] = {
> +	&dev_attr_major_version.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group tpm12_dev_group = {
> +	.attrs = tpm12_dev_attrs,
> +};
> +
> +static const struct attribute_group tpm20_dev_group = {
> +	.attrs = tpm20_dev_attrs,
>  };
>  
>  void tpm_sysfs_add_device(struct tpm_chip *chip)
>  {
> -	if (chip->flags & TPM_CHIP_FLAG_TPM2)
> -		return;
> -
>  	WARN_ON(chip->groups_cnt != 0);
> -	chip->groups[chip->groups_cnt++] = &tpm_dev_group;
> +	if (chip->flags & TPM_CHIP_FLAG_TPM2)
> +		chip->groups[chip->groups_cnt++] = &tpm20_dev_group;
> +	else
> +		chip->groups[chip->groups_cnt++] = &tpm12_dev_group;
>  }