2022-05-09 01:25:11

by Jarkko Sakkinen

[permalink] [raw]
Subject: Re: [PATCH 2/2] tpm: Add Field Upgrade mode support for Infineon TPM2 modules

On Fri, May 06, 2022 at 02:31:48PM +0200, Stefan Mahnke-Hartmann wrote:
> TPM2_GetCapability with a capability that has the property type value
> of TPM_PT_TOTAL_COMMANDS returns a zero length list, when an Infineon
> TPM2 is in Field Upgrade mode.
> Since an Infineon TPM2.0 in Field Upgrade mode returns RC_SUCCESS on
> TPM2_Startup, the Field Upgrade mode has to be detected by
> TPM2_GetCapability.
>
> Signed-off-by: Stefan Mahnke-Hartmann <[email protected]>
> ---
> drivers/char/tpm/tpm2-cmd.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index e62a644ce26b..659130e2936e 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -746,6 +746,12 @@ int tpm2_auto_startup(struct tpm_chip *chip)
> }
>
> rc = tpm2_get_cc_attrs_tbl(chip);
> + /*
> + * Infineon TPM in Field Upgrade mode will return no data for the number
> + * of supported commands.
> + */
> + if (rc == -ENODATA)
> + rc = TPM2_RC_UPGRADE;

Injecting hardware error codes like this is not considered a great idea.

>
> out:
> if (rc == TPM2_RC_UPGRADE) {
> --
> 2.25.1
>

BR, Jarkko


2022-05-09 12:48:25

by Stefan Mahnke-Hartmann

[permalink] [raw]
Subject: Re: [PATCH 2/2] tpm: Add Field Upgrade mode support for Infineon TPM2 modules

On 07.05.22 21:43, Jarkko Sakkinen wrote:
> On Fri, May 06, 2022 at 02:31:48PM +0200, Stefan Mahnke-Hartmann wrote:
>> TPM2_GetCapability with a capability that has the property type value
>> of TPM_PT_TOTAL_COMMANDS returns a zero length list, when an Infineon
>> TPM2 is in Field Upgrade mode.
>> Since an Infineon TPM2.0 in Field Upgrade mode returns RC_SUCCESS on
>> TPM2_Startup, the Field Upgrade mode has to be detected by
>> TPM2_GetCapability.
>>
>> Signed-off-by: Stefan Mahnke-Hartmann <[email protected]>
>> ---
>> drivers/char/tpm/tpm2-cmd.c | 6 ++++++
>> 1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
>> index e62a644ce26b..659130e2936e 100644
>> --- a/drivers/char/tpm/tpm2-cmd.c
>> +++ b/drivers/char/tpm/tpm2-cmd.c
>> @@ -746,6 +746,12 @@ int tpm2_auto_startup(struct tpm_chip *chip)
>> }
>>
>> rc = tpm2_get_cc_attrs_tbl(chip);
>> + /*
>> + * Infineon TPM in Field Upgrade mode will return no data for the number
>> + * of supported commands.
>> + */
>> + if (rc == -ENODATA)
>> + rc = TPM2_RC_UPGRADE;
>
> Injecting hardware error codes like this is not considered a great idea.

Resetting the error code was to avoid code duplication, while following the
same rationale as Mårten's patch. I can also add the -ENODATA to the if clause
below or duplicate the code block (similar to Mårten's). Do you have a better
suggestion?

>
>>
>> out:
>> if (rc == TPM2_RC_UPGRADE) {
>> --
>> 2.25.1
>>
>
> BR, Jarkko


2022-05-11 20:33:13

by Jarkko Sakkinen

[permalink] [raw]
Subject: Re: [PATCH 2/2] tpm: Add Field Upgrade mode support for Infineon TPM2 modules

On Mon, May 09, 2022 at 02:50:18PM +0200, Stefan Mahnke-Hartmann wrote:
> On 07.05.22 21:43, Jarkko Sakkinen wrote:
> > On Fri, May 06, 2022 at 02:31:48PM +0200, Stefan Mahnke-Hartmann wrote:
> >> TPM2_GetCapability with a capability that has the property type value
> >> of TPM_PT_TOTAL_COMMANDS returns a zero length list, when an Infineon
> >> TPM2 is in Field Upgrade mode.
> >> Since an Infineon TPM2.0 in Field Upgrade mode returns RC_SUCCESS on
> >> TPM2_Startup, the Field Upgrade mode has to be detected by
> >> TPM2_GetCapability.
> >>
> >> Signed-off-by: Stefan Mahnke-Hartmann <[email protected]>
> >> ---
> >> drivers/char/tpm/tpm2-cmd.c | 6 ++++++
> >> 1 file changed, 6 insertions(+)
> >>
> >> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> >> index e62a644ce26b..659130e2936e 100644
> >> --- a/drivers/char/tpm/tpm2-cmd.c
> >> +++ b/drivers/char/tpm/tpm2-cmd.c
> >> @@ -746,6 +746,12 @@ int tpm2_auto_startup(struct tpm_chip *chip)
> >> }
> >>
> >> rc = tpm2_get_cc_attrs_tbl(chip);
> >> + /*
> >> + * Infineon TPM in Field Upgrade mode will return no data for the number
> >> + * of supported commands.
> >> + */
> >> + if (rc == -ENODATA)
> >> + rc = TPM2_RC_UPGRADE;
> >
> > Injecting hardware error codes like this is not considered a great idea.
>
> Resetting the error code was to avoid code duplication, while following the
> same rationale as M?rten's patch. I can also add the -ENODATA to the if clause
> below or duplicate the code block (similar to M?rten's). Do you have a better
> suggestion?

I'd do that instead. It documents better the conditions.

BR, Jarkko