On Wed, Jan 13, 2021 at 03:26:33PM -0800, James Bottomley wrote:
> Create sysfs per hash groups with 24 PCR files in them one group,
> named pcr-<hash>, for each agile hash of the TPM. The files are
> plugged in to a PCR read function which is TPM version agnostic, so
> this works also for TPM 1.2 but the hash is only sha1 in that case.
>
> Note: the macros used to create the hashes emit spurious checkpatch
> warnings. Do not try to "fix" them as checkpatch recommends, otherwise
> they'll break.
>
> Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> Reviewed-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>
> Tested-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx>
>
> ---
>
> v2: fix TPM 1.2 legacy links failure
> v3: fix warn on and add note to tpm_algorithms
> v4: reword commit and add tested-by
> v5: algorithm spelling fix WARN->dev_err
> ---
> drivers/char/tpm/tpm-sysfs.c | 179 +++++++++++++++++++++++++++++++++++
> include/linux/tpm.h | 9 +-
> 2 files changed, 187 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
> index e2ff0b273a0f..63f03cfb8e6a 100644
> --- a/drivers/char/tpm/tpm-sysfs.c
> +++ b/drivers/char/tpm/tpm-sysfs.c
> @@ -337,11 +337,190 @@ static const struct attribute_group tpm2_dev_group = {
> .attrs = tpm2_dev_attrs,
> };
>
> +struct tpm_pcr_attr {
> + int alg_id;
> + int pcr;
> + struct device_attribute attr;
> +};
> +
> +#define to_tpm_pcr_attr(a) container_of(a, struct tpm_pcr_attr, attr)
> +
> +static ssize_t pcr_value_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct tpm_pcr_attr *ha = to_tpm_pcr_attr(attr);
> + struct tpm_chip *chip = to_tpm_chip(dev);
> + struct tpm_digest digest;
> + int i;
> + int digest_size = 0;
> + int rc;
> + char *str = buf;
> +
> + for (i = 0; i < chip->nr_allocated_banks; i++)
> + if (ha->alg_id == chip->allocated_banks[i].alg_id)
> + digest_size = chip->allocated_banks[i].digest_size;
> + /* should never happen */
> + if (!digest_size)
> + return -EINVAL;
> +
> + digest.alg_id = ha->alg_id;
> + rc = tpm_pcr_read(chip, ha->pcr, &digest);
> + if (rc)
> + return rc;
> + for (i = 0; i < digest_size; i++)
> + str += sprintf(str, "%02X", digest.digest[i]);
> + str += sprintf(str, "\n");
Please use sysfs_emit() and sysfs_emit_at() for new sysfs files.
> +/* ignore checkpatch warning about trailing ; in macro. */
> +#define PCR_ATTR(_alg, _hash, _pcr) \
> + static struct tpm_pcr_attr dev_attr_pcr_##_hash##_##_pcr = { \
> + .alg_id = _alg, \
> + .pcr = _pcr, \
> + .attr = { \
> + .attr = { \
> + .name = __stringify(_pcr), \
> + .mode = 0444 \
> + }, \
> + .show = pcr_value_show \
Can you use __ATTR_RO()? "open" coding the sysfs mode is frowned apon
these days.
thanks,
greg k-h
