[PATCH 1/2] tpm: Fix buffer access in tpm2_get_tpm_pt()

[PATCH 1/2] tpm: Fix buffer access in tpm2_get_tpm_pt()

[Stefan Mahnke-Hartmann]

Under certain conditions uninitialized memory will be accessed.
As described by TCG Trusted Platform Module Library Specification,
rev. 1.59 (Part 3: Commands), if a TPM2_GetCapability is received,
requesting a capability, the TPM in Field Upgrade mode may return a
zero length list.
Check the property count in tpm2_get_tpm_pt().

Fixes: 2ab3241161b3 ("tpm: migrate tpm2_get_tpm_pt() to use struct tpm_buf")
Cc: stable@vger.kernel.org
Signed-off-by: Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@infineon.com>
---
 drivers/char/tpm/tpm2-cmd.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 4704fa553098..e62a644ce26b 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -400,7 +400,10 @@ ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
 	if (!rc) {
 		out = (struct tpm2_get_cap_out *)
 			&buf.data[TPM_HEADER_SIZE];
-		*value = be32_to_cpu(out->value);
+		if (be32_to_cpu(out->property_cnt) > 0)
+			*value = be32_to_cpu(out->value);
+		else
+			rc = -ENODATA;
 	}
 	tpm_buf_destroy(&buf);
 	return rc;
-- 
2.25.1

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

[Stefan Mahnke-Hartmann]

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 <stefan.mahnke-hartmann@infineon.com>
---
 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;
 
 out:
 	if (rc == TPM2_RC_UPGRADE) {
-- 
2.25.1

Re: [PATCH 1/2] tpm: Fix buffer access in tpm2_get_tpm_pt()

[Jarkko Sakkinen]

On Fri, May 06, 2022 at 02:31:46PM +0200, Stefan Mahnke-Hartmann wrote:
> Under certain conditions uninitialized memory will be accessed.
> As described by TCG Trusted Platform Module Library Specification,
> rev. 1.59 (Part 3: Commands), if a TPM2_GetCapability is received,
> requesting a capability, the TPM in Field Upgrade mode may return a
                                      ~~~~~~~~~~~~~~~~~~

Looks like random picks for casing: two words with upper case letter and
one with lowe case.

> zero length list.
> Check the property count in tpm2_get_tpm_pt().
> 
> Fixes: 2ab3241161b3 ("tpm: migrate tpm2_get_tpm_pt() to use struct tpm_buf")
> Cc: stable@vger.kernel.org
> Signed-off-by: Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@infineon.com>

Which section is this in that specification documented?

I looked into section 30.2 but could not find the part that documents this
behaviour, i.e. returning success in FW upgrade mode. Why it wouldn't just
return TPM_RC_UPGRADE?

BR, Jarkko

 

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

[Jarkko Sakkinen]

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 <stefan.mahnke-hartmann@infineon.com>
> ---
>  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

Re: [PATCH 1/2] tpm: Fix buffer access in tpm2_get_tpm_pt()

[Stefan Mahnke-Hartmann]

On 07.05.22 21:43, Jarkko Sakkinen wrote:
> On Fri, May 06, 2022 at 02:31:46PM +0200, Stefan Mahnke-Hartmann wrote:
>> Under certain conditions uninitialized memory will be accessed.
>> As described by TCG Trusted Platform Module Library Specification,
>> rev. 1.59 (Part 3: Commands), if a TPM2_GetCapability is received,
>> requesting a capability, the TPM in Field Upgrade mode may return a
>                                       ~~~~~~~~~~~~~~~~~~
>
> Looks like random picks for casing: two words with upper case letter and
> one with lowe case.

In the TCG specification it is unfortunately also inconsistent.
I will change it to lower case then.

>
>> zero length list.
>> Check the property count in tpm2_get_tpm_pt().
>>
>> Fixes: 2ab3241161b3 ("tpm: migrate tpm2_get_tpm_pt() to use struct tpm_buf")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@infineon.com>
>
> Which section is this in that specification documented?

It is described in the TCG Trusted Platform Module Library Specification,
rev. 1.59 (Part 3: Commands) in Chapter 30.2.1, Example 3. This example
describes the behavior in failure mode, but it may occur in other
circumstances, such as field upgrade mode.

>
> I looked into section 30.2 but could not find the part that documents this
> behaviour, i.e. returning success in FW upgrade mode. Why it wouldn't just
> return TPM_RC_UPGRADE?

Since some computer system failed booting up in case the TPM returned
anything else than SUCCESS, therefore Infineon decided to return SUCCESS
when TPM is in field upgrade mode.

BR, Stefan

>
> BR, Jarkko
>
>  

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

[Stefan Mahnke-Hartmann]

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 <stefan.mahnke-hartmann@infineon.com>
>> ---
>>  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

Re: [PATCH 1/2] tpm: Fix buffer access in tpm2_get_tpm_pt()

[Jarkko Sakkinen]

On Mon, May 09, 2022 at 01:48:09PM +0200, Stefan Mahnke-Hartmann wrote:
> On 07.05.22 21:43, Jarkko Sakkinen wrote:
> > On Fri, May 06, 2022 at 02:31:46PM +0200, Stefan Mahnke-Hartmann wrote:
> >> Under certain conditions uninitialized memory will be accessed.
> >> As described by TCG Trusted Platform Module Library Specification,
> >> rev. 1.59 (Part 3: Commands), if a TPM2_GetCapability is received,
> >> requesting a capability, the TPM in Field Upgrade mode may return a
> >                                       ~~~~~~~~~~~~~~~~~~
> >
> > Looks like random picks for casing: two words with upper case letter and
> > one with lowe case.
> 
> In the TCG specification it is unfortunately also inconsistent.
> I will change it to lower case then.
> 
> >
> >> zero length list.
> >> Check the property count in tpm2_get_tpm_pt().
> >>
> >> Fixes: 2ab3241161b3 ("tpm: migrate tpm2_get_tpm_pt() to use struct tpm_buf")
> >> Cc: stable@vger.kernel.org
> >> Signed-off-by: Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@infineon.com>
> >
> > Which section is this in that specification documented?
> 
> It is described in the TCG Trusted Platform Module Library Specification,
> rev. 1.59 (Part 3: Commands) in Chapter 30.2.1, Example 3. This example
> describes the behavior in failure mode, but it may occur in other
> circumstances, such as field upgrade mode.
> 
> >
> > I looked into section 30.2 but could not find the part that documents this
> > behaviour, i.e. returning success in FW upgrade mode. Why it wouldn't just
> > return TPM_RC_UPGRADE?
> 
> Since some computer system failed booting up in case the TPM returned
> anything else than SUCCESS, therefore Infineon decided to return SUCCESS
> when TPM is in field upgrade mode.

OK, fair enough. This would be a place for inline comment though, given
that it is not obvious by intuition.

BR, Jarkko

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

[Jarkko Sakkinen]

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 <stefan.mahnke-hartmann@infineon.com>
> >> ---
> >>  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?

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

BR, Jarkko