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

[Nayna <nayna-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

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-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> ---
>   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 ?

struct cap_out {
   u32 cap_id;
   union cap_data {
      struct tpml_pcr_selection assignedPCR;
      struct tpml_tagged_tpm_property tpmProperties;
      struct tpml_handle handles;
   }
}

And then the calling function, map union to the cap_data expected as per 
id, and parse it.

Thanks & Regards,
   - Nayna


>   {
>   	struct tpm2_cmd cmd;
>   	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(property_id);
> -	cmd.params.get_tpm_pt_in.property_cnt = cpu_to_be32(1);
> +	cmd.header.in = tpm2_getcap_header;
> +	cmd.params.getcap_in.cap_id = cpu_to_be32(cap_id);
> +	cmd.params.getcap_in.property_id = cpu_to_be32(property_id);
> +	cmd.params.getcap_in.property_cnt = cpu_to_be32(1);
>
>   	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd), 0, desc);
>   	if (!rc)
> -		*value = be32_to_cpu(cmd.params.get_tpm_pt_out.value);
> +		*value = be32_to_cpu(cmd.params.getcap_out.value);
>
>   	return rc;
>   }
> -EXPORT_SYMBOL_GPL(tpm2_get_tpm_pt);
> +EXPORT_SYMBOL_GPL(tpm2_getcap_cmd);
>
>   #define TPM2_STARTUP_IN_SIZE \
>   	(sizeof(struct tpm_input_header) + \
> @@ -978,10 +976,10 @@ int tpm2_probe(struct tpm_chip *chip)
>   	struct tpm2_cmd cmd;
>   	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);
> +	cmd.header.in = tpm2_getcap_header;
> +	cmd.params.getcap_in.cap_id = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES);
> +	cmd.params.getcap_in.property_id = cpu_to_be32(TPM2_PT_FAMILY_INDICATOR);
> +	cmd.params.getcap_in.property_cnt = cpu_to_be32(1);
>
>   	rc = tpm_transmit_cmd(chip, &cmd, sizeof(cmd),  0, NULL);
>   	if (rc <  0)
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index e3bf31b..792ccd1 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -528,7 +528,8 @@ static int tpm_tis_gen_interrupt(struct tpm_chip *chip)
>   	cap_t cap;
>
>   	if (chip->flags & TPM_CHIP_FLAG_TPM2)
> -		return tpm2_get_tpm_pt(chip, 0x100, &cap2, desc);
> +		return tpm2_getcap_cmd(chip, TPM2_CAP_TPM_PROPERTIES,
> +				       TPM2_PT_FAMILY_INDICATOR, &cap2, desc);
>   	else
>   		return tpm_getcap(chip, TPM_CAP_PROP_TIS_TIMEOUT, &cap, desc);
>   }
>


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