[PATCH AUTOSEL 4.19 106/146] tpm: suppress transmit cmd error logs when TPM 1.2 is disabled/deactivated

Sasha Levin
2018-10-31T23:45:12Z

From: Javier Martinez Canillas <javierm@redhat.com>

[ Upstream commit 0d6d0d62d9505a9816716aa484ebd0b04c795063 ]

For TPM 1.2 chips the system setup utility allows to set the TPM device in
one of the following states:

* Active: Security chip is functional
* Inactive: Security chip is visible, but is not functional
* Disabled: Security chip is hidden and is not functional

When choosing the "Inactive" state, the TPM 1.2 device is enumerated and
registered, but sending TPM commands fail with either TPM_DEACTIVATED or
TPM_DISABLED depending if the firmware deactivated or disabled the TPM.

Since these TPM 1.2 error codes don't have special treatment, inactivating
the TPM leads to a very noisy kernel log buffer that shows messages like
the following:

tpm_tis 00:05: 1.2 TPM (device-id 0x0, rev-id 78)
tpm tpm0: A TPM error (6) occurred attempting to read a pcr value
tpm tpm0: TPM is disabled/deactivated (0x6)
tpm tpm0: A TPM error (6) occurred attempting get random
tpm tpm0: A TPM error (6) occurred attempting to read a pcr value
ima: No TPM chip found, activating TPM-bypass! (rc=6)
tpm tpm0: A TPM error (6) occurred attempting get random
tpm tpm0: A TPM error (6) occurred attempting get random
tpm tpm0: A TPM error (6) occurred attempting get random
tpm tpm0: A TPM error (6) occurred attempting get random

Let's just suppress error log messages for the TPM_{DEACTIVATED,DISABLED}
return codes, since this is expected when the TPM 1.2 is set to Inactive.

In that case the kernel log is cleaner and less confusing for users, i.e:

tpm_tis 00:05: 1.2 TPM (device-id 0x0, rev-id 78)
tpm tpm0: TPM is disabled/deactivated (0x6)
ima: No TPM chip found, activating TPM-bypass! (rc=6)

Reported-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/char/tpm/tpm-interface.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 1a803b0cf980..9f61106502a9 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -663,7 +663,8 @@ ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_space *space,
return len;

err = be32_to_cpu(header->return_code);
- if (err != 0 && desc)
+ if (err != 0 && err != TPM_ERR_DISABLED && err != TPM_ERR_DEACTIVATED
+ && desc)
dev_err(&chip->dev, "A TPM error (%d) occurred %s\n", err,
desc);
if (err)
--
2.17.1