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@xxxxxxxxxxxx>
---
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
