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Message-Id: <582D998C.40605@linux.vnet.ibm.com>
Date: Thu, 17 Nov 2016 17:20:36 +0530
From: Nayna <nayna@...ux.vnet.ibm.com>
To: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc: Peter Huewe <peterhuewe@....de>,
"moderated list:TPM DEVICE DRIVER"
<tpmdd-devel@...ts.sourceforge.net>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [tpmdd-devel] [PATCH RFC 2/2] tpm: refactor tpm2_get_tpm_pt to
tpm2_getcap_cmd
On 11/12/2016 05:32 AM, 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@...ux.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.
I agree with the idea of not using union.
I tested this for capability TPM2_CAP_PCRS. It seems TPM2_CAP_PCRS
capability always returns full PCR allocation, and more_data as 0, So, I
think the idea of looping over based on more_data may not work for this
capability.
I was thinking in place of having u32 *value returning actual value, can
we have it as void *value, where getcap_cmd will memcpy its out
parameter content after subcap_id to value, and then calling function
typecast to expected type and use it.
Please let me know if I am missing something in using this function.
Thanks & Regards,
- Nayna
>
> /Jarkko
>
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