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

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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>
This commit is contained in:
Stefan Mahnke-Hartmann 2022-06-03 10:41:58 +02:00 committed by Jarkko Sakkinen
parent 200e340f21
commit 5e3a3f27cb
2 changed files with 7 additions and 1 deletions
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1
drivers/char/tpm/tpm.h
View File

@ -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

7
drivers/char/tpm/tpm1-cmd.c
View File

@ -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;
}