[v3] tpm: Add upgrade/reduced mode support for TPM1.2 modules

[PATCH v3] tpm: Add upgrade/reduced mode support for TPM1.2 modules

Posted by Stefan Mahnke-Hartmann 3 years, 10 months ago

In case a TPM in failure mode is detected, the TPM should be accessible
through a transparent communication channel for analysing purposes (e.g.
TPM_GetTestResult) or a field upgrade. Since a TPM in failure mode has
similar reduced functionality as in field upgrade mode, the flag
TPM_CHIP_FLAG_FIRMWARE_UPGRADE is also valid.

As described in TCG TPM Main Part1 Design Principles, Revision 116,
chapter 9.2.1. the TPM also allows an update function in case a TPM is
in failure mode.

If the TPM in failure mode is detected, the function tpm1_auto_startup()
sets TPM_CHIP_FLAG_FIRMWARE_UPGRADE flag, which is used later during
driver initialization/deinitialization to disable functionality which
makes no sense or will fail in the current TPM state. The following
functionality is affected:
 * Do not register TPM as a hwrng
 * Do not get pcr allocation
 * Do not register sysfs entries which provide information impossible to
   obtain in limited mode

Signed-off-by: Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@infineon.com>
---
Changelog:
 * v3:
   * Change kernel messages

 drivers/char/tpm/tpm.h      | 1 +
 drivers/char/tpm/tpm1-cmd.c | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 2163c6ee0d36..24ee4e1cc452 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -55,6 +55,7 @@ enum tpm_addr {
 #define TPM_WARN_DOING_SELFTEST 0x802
 #define TPM_ERR_DEACTIVATED     0x6
 #define TPM_ERR_DISABLED        0x7
+#define TPM_ERR_FAILEDSELFTEST  0x1C
 #define TPM_ERR_INVALID_POSTINIT 38
 
 #define TPM_TAG_RQU_COMMAND 193
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index f7dc986fa4a0..cf64c7385105 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -709,7 +709,12 @@ int tpm1_auto_startup(struct tpm_chip *chip)
 	if (rc)
 		goto out;
 	rc = tpm1_do_selftest(chip);
-	if (rc) {
+	if (rc == TPM_ERR_FAILEDSELFTEST) {
+		dev_warn(&chip->dev, "TPM self test failed, switching to the firmware upgrade mode\n");
+		/* A TPM in this state possibly allows or needs a firmware upgrade */
+		chip->flags |= TPM_CHIP_FLAG_FIRMWARE_UPGRADE;
+		return 0;
+	} else if (rc) {
 		dev_err(&chip->dev, "TPM self test failed\n");
 		goto out;
 	}
-- 
2.25.1

Re: [PATCH v3] tpm: Add upgrade/reduced mode support for TPM1.2 modules

Posted by Jarkko Sakkinen 3 years, 10 months ago

On Fri, Jun 03, 2022 at 10:41:58AM +0200, Stefan Mahnke-Hartmann wrote:
> In case a TPM in failure mode is detected, the TPM should be accessible
> through a transparent communication channel for analysing purposes (e.g.
> TPM_GetTestResult) or a field upgrade. Since a TPM in failure mode has
> similar reduced functionality as in field upgrade mode, the flag
> TPM_CHIP_FLAG_FIRMWARE_UPGRADE is also valid.
> 
> As described in TCG TPM Main Part1 Design Principles, Revision 116,
> chapter 9.2.1. the TPM also allows an update function in case a TPM is
> in failure mode.
> 
> If the TPM in failure mode is detected, the function tpm1_auto_startup()
> sets TPM_CHIP_FLAG_FIRMWARE_UPGRADE flag, which is used later during
> driver initialization/deinitialization to disable functionality which
> makes no sense or will fail in the current TPM state. The following
> functionality is affected:
>  * Do not register TPM as a hwrng
>  * Do not get pcr allocation
>  * Do not register sysfs entries which provide information impossible to
>    obtain in limited mode
> 
> Signed-off-by: Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@infineon.com>
> ---
> Changelog:
>  * v3:
>    * Change kernel messages
> 
>  drivers/char/tpm/tpm.h      | 1 +
>  drivers/char/tpm/tpm1-cmd.c | 7 ++++++-
>  2 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index 2163c6ee0d36..24ee4e1cc452 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -55,6 +55,7 @@ enum tpm_addr {
>  #define TPM_WARN_DOING_SELFTEST 0x802
>  #define TPM_ERR_DEACTIVATED     0x6
>  #define TPM_ERR_DISABLED        0x7
> +#define TPM_ERR_FAILEDSELFTEST  0x1C
>  #define TPM_ERR_INVALID_POSTINIT 38
>  
>  #define TPM_TAG_RQU_COMMAND 193
> diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
> index f7dc986fa4a0..cf64c7385105 100644
> --- a/drivers/char/tpm/tpm1-cmd.c
> +++ b/drivers/char/tpm/tpm1-cmd.c
> @@ -709,7 +709,12 @@ int tpm1_auto_startup(struct tpm_chip *chip)
>  	if (rc)
>  		goto out;
>  	rc = tpm1_do_selftest(chip);
> -	if (rc) {
> +	if (rc == TPM_ERR_FAILEDSELFTEST) {
> +		dev_warn(&chip->dev, "TPM self test failed, switching to the firmware upgrade mode\n");
> +		/* A TPM in this state possibly allows or needs a firmware upgrade */
> +		chip->flags |= TPM_CHIP_FLAG_FIRMWARE_UPGRADE;
> +		return 0;
> +	} else if (rc) {
>  		dev_err(&chip->dev, "TPM self test failed\n");
>  		goto out;
>  	}
> -- 
> 2.25.1
> 

I think this looks good now, thanks for patience:

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko

Re: [PATCH v3] tpm: Add upgrade/reduced mode support for TPM1.2 modules

Posted by Jarkko Sakkinen 3 years, 10 months ago

On Tue, Jun 07, 2022 at 12:49:11PM +0300, Jarkko Sakkinen wrote:
> On Fri, Jun 03, 2022 at 10:41:58AM +0200, Stefan Mahnke-Hartmann wrote:
> > In case a TPM in failure mode is detected, the TPM should be accessible
> > through a transparent communication channel for analysing purposes (e.g.
> > TPM_GetTestResult) or a field upgrade. Since a TPM in failure mode has
> > similar reduced functionality as in field upgrade mode, the flag
> > TPM_CHIP_FLAG_FIRMWARE_UPGRADE is also valid.
> > 
> > As described in TCG TPM Main Part1 Design Principles, Revision 116,
> > chapter 9.2.1. the TPM also allows an update function in case a TPM is
> > in failure mode.
> > 
> > If the TPM in failure mode is detected, the function tpm1_auto_startup()
> > sets TPM_CHIP_FLAG_FIRMWARE_UPGRADE flag, which is used later during
> > driver initialization/deinitialization to disable functionality which
> > makes no sense or will fail in the current TPM state. The following
> > functionality is affected:
> >  * Do not register TPM as a hwrng
> >  * Do not get pcr allocation
> >  * Do not register sysfs entries which provide information impossible to
> >    obtain in limited mode
> > 
> > Signed-off-by: Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@infineon.com>
> > ---
> > Changelog:
> >  * v3:
> >    * Change kernel messages
> > 
> >  drivers/char/tpm/tpm.h      | 1 +
> >  drivers/char/tpm/tpm1-cmd.c | 7 ++++++-
> >  2 files changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> > index 2163c6ee0d36..24ee4e1cc452 100644
> > --- a/drivers/char/tpm/tpm.h
> > +++ b/drivers/char/tpm/tpm.h
> > @@ -55,6 +55,7 @@ enum tpm_addr {
> >  #define TPM_WARN_DOING_SELFTEST 0x802
> >  #define TPM_ERR_DEACTIVATED     0x6
> >  #define TPM_ERR_DISABLED        0x7
> > +#define TPM_ERR_FAILEDSELFTEST  0x1C
> >  #define TPM_ERR_INVALID_POSTINIT 38
> >  
> >  #define TPM_TAG_RQU_COMMAND 193
> > diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
> > index f7dc986fa4a0..cf64c7385105 100644
> > --- a/drivers/char/tpm/tpm1-cmd.c
> > +++ b/drivers/char/tpm/tpm1-cmd.c
> > @@ -709,7 +709,12 @@ int tpm1_auto_startup(struct tpm_chip *chip)
> >  	if (rc)
> >  		goto out;
> >  	rc = tpm1_do_selftest(chip);
> > -	if (rc) {
> > +	if (rc == TPM_ERR_FAILEDSELFTEST) {
> > +		dev_warn(&chip->dev, "TPM self test failed, switching to the firmware upgrade mode\n");
> > +		/* A TPM in this state possibly allows or needs a firmware upgrade */
> > +		chip->flags |= TPM_CHIP_FLAG_FIRMWARE_UPGRADE;
> > +		return 0;
> > +	} else if (rc) {
> >  		dev_err(&chip->dev, "TPM self test failed\n");
> >  		goto out;
> >  	}
> > -- 
> > 2.25.1
> > 
> 
> I think this looks good now, thanks for patience:
> 
> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

applied

BR, Jarkko