Re: [tpmdd-devel] [PATCH RFC 2/2] tpm: refactor tpm2_get_tpm_pt to tpm2_getcap_cmd

[Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>]

On Fri, Nov 11, 2016 at 04:02:43PM -0800, Jarkko Sakkinen wrote:
> On Fri, Nov 11, 2016 at 09:51:45AM +0530, Nayna wrote:
> > 
> > 
> > On 10/09/2016 03:44 PM, Jarkko Sakkinen wrote:
> > > Refactored tpm2_get_tpm_pt to tpm2_getcap_cmd, which means that it also
> > > takes capability ID as input. This is required to access
> > > TPM_CAP_HANDLES, which contains metadata needed for swapping transient
> > > data.
> > > 
> > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > > ---
> > >   drivers/char/tpm/tpm.h          |  6 +++-
> > >   drivers/char/tpm/tpm2-cmd.c     | 64 ++++++++++++++++++++---------------------
> > >   drivers/char/tpm/tpm_tis_core.c |  3 +-
> > >   3 files changed, 38 insertions(+), 35 deletions(-)
> > > 
> > > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> > > index 0fab6d5..8176f42 100644
> > > --- a/drivers/char/tpm/tpm.h
> > > +++ b/drivers/char/tpm/tpm.h
> > > @@ -85,6 +85,10 @@ enum tpm2_capabilities {
> > >   	TPM2_CAP_TPM_PROPERTIES = 6,
> > >   };
> > > 
> > > +enum tpm2_properties {
> > > +	TPM2_PT_FAMILY_INDICATOR	= 0x100,
> > > +};
> > > +
> > >   enum tpm2_startup_types {
> > >   	TPM2_SU_CLEAR	= 0x0000,
> > >   	TPM2_SU_STATE	= 0x0001,
> > > @@ -485,7 +489,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
> > >   int tpm2_unseal_trusted(struct tpm_chip *chip,
> > >   			struct trusted_key_payload *payload,
> > >   			struct trusted_key_options *options);
> > > -ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,
> > > +ssize_t tpm2_getcap_cmd(struct tpm_chip *chip, u32 cap_id, u32 property_id,
> > >   			u32 *value, const char *desc);
> > > 
> > >   int tpm2_auto_startup(struct tpm_chip *chip);
> > > diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> > > index 2900e18..fcf3d86 100644
> > > --- a/drivers/char/tpm/tpm2-cmd.c
> > > +++ b/drivers/char/tpm/tpm2-cmd.c
> > > @@ -111,13 +111,13 @@ struct tpm2_pcr_extend_in {
> > >   	u8				digest[TPM_DIGEST_SIZE];
> > >   } __packed;
> > > 
> > > -struct tpm2_get_tpm_pt_in {
> > > +struct tpm2_getcap_in {
> > >   	__be32	cap_id;
> > >   	__be32	property_id;
> > >   	__be32	property_cnt;
> > >   } __packed;
> > > 
> > > -struct tpm2_get_tpm_pt_out {
> > > +struct tpm2_getcap_out {
> > >   	u8	more_data;
> > >   	__be32	subcap_id;
> > >   	__be32	property_cnt;
> > > @@ -140,8 +140,8 @@ union tpm2_cmd_params {
> > >   	struct	tpm2_pcr_read_in	pcrread_in;
> > >   	struct	tpm2_pcr_read_out	pcrread_out;
> > >   	struct	tpm2_pcr_extend_in	pcrextend_in;
> > > -	struct	tpm2_get_tpm_pt_in	get_tpm_pt_in;
> > > -	struct	tpm2_get_tpm_pt_out	get_tpm_pt_out;
> > > +	struct	tpm2_getcap_in		getcap_in;
> > > +	struct	tpm2_getcap_out		getcap_out;
> > >   	struct	tpm2_get_random_in	getrandom_in;
> > >   	struct	tpm2_get_random_out	getrandom_out;
> > >   };
> > > @@ -435,16 +435,6 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *out, size_t max)
> > >   	return total ? total : -EIO;
> > >   }
> > > 
> > > -#define TPM2_GET_TPM_PT_IN_SIZE \
> > > -	(sizeof(struct tpm_input_header) + \
> > > -	 sizeof(struct tpm2_get_tpm_pt_in))
> > > -
> > > -static const struct tpm_input_header tpm2_get_tpm_pt_header = {
> > > -	.tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
> > > -	.length = cpu_to_be32(TPM2_GET_TPM_PT_IN_SIZE),
> > > -	.ordinal = cpu_to_be32(TPM2_CC_GET_CAPABILITY)
> > > -};
> > > -
> > >   /**
> > >    * Append TPMS_AUTH_COMMAND to the buffer. The buffer must be allocated with
> > >    * tpm_buf_alloc().
> > > @@ -750,35 +740,43 @@ out:
> > >   	return rc;
> > >   }
> > > 
> > > +#define TPM2_GETCAP_IN_SIZE \
> > > +	(sizeof(struct tpm_input_header) + sizeof(struct tpm2_getcap_in))
> > > +
> > > +static const struct tpm_input_header tpm2_getcap_header = {
> > > +	.tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
> > > +	.length = cpu_to_be32(TPM2_GETCAP_IN_SIZE),
> > > +	.ordinal = cpu_to_be32(TPM2_CC_GET_CAPABILITY)
> > > +};
> > > +
> > >   /**
> > > - * tpm2_get_tpm_pt() - get value of a TPM_CAP_TPM_PROPERTIES type property
> > > - * @chip:		TPM chip to use.
> > > - * @property_id:	property ID.
> > > - * @value:		output variable.
> > > + * tpm2_getcap_cmd() - execute a TPM2_GetCapability command
> > > + * @chip:		TPM chip to use
> > > + * @cap_id:		capability ID
> > > + * @property_id:	property ID
> > > + * @value:		value of the property
> > >    * @desc:		passed to tpm_transmit_cmd()
> > >    *
> > > - * 0 is returned when the operation is successful. If a negative number is
> > > - * returned it remarks a POSIX error code. If a positive number is returned
> > > - * it remarks a TPM error.
> > > + * Return: same as with tpm_transmit_cmd
> > >    */
> > > -ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
> > > -			const char *desc)
> > > +ssize_t tpm2_getcap_cmd(struct tpm_chip *chip, u32 cap_id, u32 property_id,
> > > +			u32 *value, const char *desc)
> > 
> > This function currently returns single value "u32 *value" as output data.
> > 
> > Some calling function expect list of values from capabilities output.
> > For eg., get_active_banks() use TPM_CAP_PCRS capability to retrieve list of
> > active banks. And this capability returns array of pcr selections(which is a
> > struct representing each active PCR bank)
> > 
> > I was thinking, can we define output parameter as struct of cap_id and union
> > of expected cap_data ?
> 
> Unless you have major concerns about performance, which I think are not
> relevant here, calling this in a loop is perfectly adequate and a lot of
> simpler than having a generic version (with moreData handling and
> everything).
> 
> I would rather see uses of struct cap_t to shrink than to expand. The
> same goes for other horrific unions that exist today in the driver.

If you are fine with this patch (give Reviewed-by) I can apply this
and add to my 4.10 pull request so that we have common baseline to
develop both event log and the resource manager.

This is a very low risk commit to take to 4.10 because it is only used
for interrupt generation in the TIS driver at the moment.

/Jarkko