[PATCH] tpm: Add check for Failure mode for TPM2 modules

* [PATCH] tpm: Add check for Failure mode for TPM2 modules
@ 2022-04-25 10:25 Mårten Lindahl
  2022-04-25 14:03 ` Jarkko Sakkinen
  0 siblings, 1 reply; 9+ messages in thread
From: Mårten Lindahl @ 2022-04-25 10:25 UTC (permalink / raw)
  To: Peter Huewe, Jarkko Sakkinen
  Cc: Jason Gunthorpe, linux-integrity, kernel, Mårten Lindahl

In commit 0aa698787aa2 ("tpm: Add Upgrade/Reduced mode support for
TPM2 modules") it was said that:

"If the TPM is in Failure mode, it will successfully respond to both
tpm2_do_selftest() and tpm2_startup() calls. Although, will fail to
answer to tpm2_get_cc_attrs_tbl(). Use this fact to conclude that TPM
is in Failure mode."

But a check was never added in the commit when calling
tpm2_get_cc_attrs_tbl() to conclude that the TPM is in Failure mode.
This commit corrects this by adding a check.

Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
---
 drivers/char/tpm/tpm2-cmd.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 4704fa553098..9da433521a0b 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -743,6 +743,11 @@ int tpm2_auto_startup(struct tpm_chip *chip)
 	}
 
 	rc = tpm2_get_cc_attrs_tbl(chip);
+	if (rc < 0 && rc != -ENOMEM) {
+		dev_info(&chip->dev, "TPM in field failure mode, requires firmware upgrade\n");
+		chip->flags |= TPM_CHIP_FLAG_FIRMWARE_UPGRADE;
+		rc = 0;
+	}
 
 out:
 	if (rc == TPM2_RC_UPGRADE) {
-- 
2.30.2


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