Commit 5e3a3f27 authored Jun 03, 2022 by Stefan Mahnke-Hartmann Committed by Jarkko Sakkinen Aug 03, 2022

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



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

parent 200e340f

drivers/char/tpm/tpm.h

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -55,6 +55,7 @@ enum tpm_addr {
	#define TPM_WARN_DOING_SELFTEST 0x802		#define TPM_WARN_DOING_SELFTEST 0x802
	#define TPM_ERR_DEACTIVATED 0x6		#define TPM_ERR_DEACTIVATED 0x6
	#define TPM_ERR_DISABLED 0x7		#define TPM_ERR_DISABLED 0x7
			#define TPM_ERR_FAILEDSELFTEST 0x1C
	#define TPM_ERR_INVALID_POSTINIT 38		#define TPM_ERR_INVALID_POSTINIT 38

	#define TPM_TAG_RQU_COMMAND 193		#define TPM_TAG_RQU_COMMAND 193

drivers/char/tpm/tpm1-cmd.c

+6 −1

Original line number	Original line	Diff line number	Diff line
	@@ -709,7 +709,12 @@ int tpm1_auto_startup(struct tpm_chip *chip)
	if (rc)		if (rc)
	goto out;		goto out;
	rc = tpm1_do_selftest(chip);		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");		dev_err(&chip->dev, "TPM self test failed\n");
	goto out;		goto out;
	}		}