On 01/19/2017 04:17 PM, Jarkko Sakkinen wrote:
> On Wed, Jan 18, 2017 at 07:19:06PM +0530, Nayna wrote:
>>
>>
>> On 01/18/2017 07:15 PM, Jarkko Sakkinen wrote:
>>> On Wed, Jan 18, 2017 at 03:44:49AM -0500, Nayna Jain wrote:
>>>> This patch implements the TPM 2.0 capability TPM_CAP_PCRS to
>>>> retrieve the active PCR banks from the TPM. This is needed
>>>> to enable extending all active banks as recommended by TPM 2.0
>>>> TCG Specification.
>>>>
>>>> Signed-off-by: Nayna Jain <na...@linux.vnet.ibm.com>
>>>> ---
>>>> drivers/char/tpm/tpm.h | 4 ++++
>>>> drivers/char/tpm/tpm2-cmd.c | 57
>>>> +++++++++++++++++++++++++++++++++++++++++++++
>>>> 2 files changed, 61 insertions(+)
>>>>
>>>> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
>>>> index 1ae9768..dddd573 100644
>>>> --- a/drivers/char/tpm/tpm.h
>>>> +++ b/drivers/char/tpm/tpm.h
>>>> @@ -127,6 +127,7 @@ enum tpm2_permanent_handles {
>>>> };
>>>>
>>>> enum tpm2_capabilities {
>>>> + TPM2_CAP_PCRS = 5,
>>>> TPM2_CAP_TPM_PROPERTIES = 6,
>>>> };
>>>>
>>>> @@ -187,6 +188,8 @@ struct tpm_chip {
>>>>
>>>> const struct attribute_group *groups[3];
>>>> unsigned int groups_cnt;
>>>> +
>>>> + u16 active_banks[7];
>>>> #ifdef CONFIG_ACPI
>>>> acpi_handle acpi_dev_handle;
>>>> char ppi_version[TPM_PPI_VERSION_LEN + 1];
>>>> @@ -545,4 +548,5 @@ int tpm2_auto_startup(struct tpm_chip *chip);
>>>> void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type);
>>>> unsigned long tpm2_calc_ordinal_duration(struct tpm_chip *chip, u32
>>>> ordinal);
>>>> int tpm2_probe(struct tpm_chip *chip);
>>>> +ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip);
>>>> #endif
>>>> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
>>>> index 6eda239..75a7546 100644
>>>> --- a/drivers/char/tpm/tpm2-cmd.c
>>>> +++ b/drivers/char/tpm/tpm2-cmd.c
>>>> @@ -998,3 +998,60 @@ int tpm2_auto_startup(struct tpm_chip *chip)
>>>> rc = -ENODEV;
>>>> return rc;
>>>> }
>>>> +
>>>> +struct tpm2_pcr_selection {
>>>> + __be16 hash_alg;
>>>> + u8 size_of_select;
>>>> + u8 pcr_select[3];
>>>> +} __packed;
>>>> +
>>>> +/**
>>>> + * tpm2_get_pcr_allocation() - get TPM active PCR banks.
>>>> + *
>>>> + * @chip: TPM chip to use.
>>>> + *
>>>> + * Return: Same as with tpm_transmit_cmd.
>>>> + */
>>>> +ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
>>>> +{
>>>> + struct tpm2_pcr_selection pcr_selection;
>>>> + struct tpm_buf buf;
>>>> + void *marker;
>>>> + unsigned int count = 0;
>>>
>>> You shouldn't initialize 'count'.
>>
>> It is initialized for reason below:
>>
>>>
>>>> + int rc;
>>>> + int i;
>>>> +
>>>> + rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
>>>> + if (rc)
>>>> + return rc;
>>>> +
>>>> + tpm_buf_append_u32(&buf, TPM2_CAP_PCRS);
>>>> + tpm_buf_append_u32(&buf, 0);
>>>> + tpm_buf_append_u32(&buf, 1);
>>>> +
>>>> + rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, 0,
>>>> + "get tpm pcr allocation");
>>>> + if (rc < 0)
>>>> + goto out;
>>
>> if tpm_transmit_cmd()fails, it jumps to out:
>> where count is used in if(..).
>
> Why the out label is placed there and not after?
Since tpm2_get_pcr_allocation() returns from here as failure,
chip->active_banks doesn't get anytime initialized.
By placing it there, for failure, chip->active_bank[0] is initialized to 0.
Then its later use like in tpm_pcr_extend(), it loops on this array till
there is a value "0"(considered as invalid) or reaches max size of array.
>
>>
>> Thanks & Regards,
>> - Nayna
>>
>>>> +
>>>> + count = be32_to_cpup(
>>>> + (__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
>>>> +
>>>> + if (count > ARRAY_SIZE(chip->active_banks))
>>>> + return -ENODEV;
>
> Hey, here's a regression (didn't notice it last time). You
> nee to call tpm_buf_destroy().
Oh!! Yes, Thanks !!. I will fix this with:
rc = -ENODEV;
goto out;
Thanks & Regards
- Nayna
>
>
>>>> +
>>>> + marker = &buf.data[TPM_HEADER_SIZE + 9];
>>>> + for (i = 0; i < count; i++) {
>>>> + memcpy(&pcr_selection, marker, sizeof(pcr_selection));
>>>> + chip->active_banks[i] = be16_to_cpu(pcr_selection.hash_alg);
>>>> + marker = marker + sizeof(struct tpm2_pcr_selection);
>>>> + }
>>>> +
>>>> +out:
>>>> + if (count < ARRAY_SIZE(chip->active_banks))
>>>> + chip->active_banks[count] = 0;
>>>> +
>>>> + tpm_buf_destroy(&buf);
>>>> +
>>>> + return rc;
>>>> +}
>>>> --
>>>> 2.5.0
>>>
>>> Otherwise,
>>>
>>> Reviewed-by: Jarkko Sakkinen <jarkko.sakk...@linux.intel.com>
>>>
>>> /Jarkko
>>>
>>
>
> /Jarkko
>
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