linux-kernel - Re: [PATCH] tpm: Add major

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Message-ID: <20191025184522.5txabdikcrn2dgvj@cantor>
Date:   Fri, 25 Oct 2019 11:45:22 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>
Cc:     linux-kernel@...r.kernel.org,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, linux-integrity@...r.kernel.org
Subject: Re: [PATCH] tpm: Add major_version sysfs file

On Fri Oct 25 19, Mimi Zohar wrote:
>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@...ux.intel.com>
>> Cc: Peter Huewe <peterhuewe@....de>
>> Cc: Jason Gunthorpe <jgg@...pe.ca>
>> Cc: linux-integrity@...r.kernel.org
>> Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com>
>
>thanks!
>
>Reviewed-by: Mimi Zohar <zohar@...ux.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?
>
>

Yes, there should be an entry added to
Documentation/ABI/stable/sysfs-class-tpm.
I will fix that up and the TCG not being uppercase in a v2.

Should Documentation/ABI/stable/sysfs-class-tpm updated in
some way to reflect that those are all links under device
now and not actually there.

>> ---
>>  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;
>>  }
>