linux-kernel - [PATCH 1/2 v2] tpm: provide a way to override the chip returned durations

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Date:   Tue, 27 Aug 2019 17:46:20 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     linux-integrity@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Peter Huewe <peterhuewe@....de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        Alexey Klimov <aklimov@...hat.com>
Subject: [PATCH 1/2 v2] tpm: provide a way to override the chip returned durations

Patch adds method ->update_durations to override returned
durations in case TPM chip misbehaves for TPM 1.2 drivers.

Cc: Peter Huewe <peterhuewe@....de>
Cc: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc: Jason Gunthorpe <jgg@...pe.ca>
Signed-off-by: Alexey Klimov <aklimov@...hat.com>
Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com>
---
v2: newline cleanup as requested by Jarkko

 drivers/char/tpm/tpm1-cmd.c | 15 +++++++++++++++
 include/linux/tpm.h         |  2 ++
 2 files changed, 17 insertions(+)

diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index 149e953ca369..ca7158fa6e6c 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -343,6 +343,7 @@ int tpm1_get_timeouts(struct tpm_chip *chip)
 {
 	cap_t cap;
 	unsigned long timeout_old[4], timeout_chip[4], timeout_eff[4];
+	unsigned long durations[3];
 	ssize_t rc;
 
 	rc = tpm1_getcap(chip, TPM_CAP_PROP_TIS_TIMEOUT, &cap, NULL,
@@ -427,6 +428,20 @@ int tpm1_get_timeouts(struct tpm_chip *chip)
 		usecs_to_jiffies(be32_to_cpu(cap.duration.tpm_long));
 	chip->duration[TPM_LONG_LONG] = 0; /* not used under 1.2 */
 
+	/*
+	 * Provide the ability for vendor overrides of duration values in case
+	 * of misreporting.
+	 */
+	if (chip->ops->update_durations)
+		chip->ops->update_durations(chip, durations);
+
+	if (chip->duration_adjusted) {
+		dev_info(&chip->dev, HW_ERR "Adjusting reported durations.");
+		chip->duration[TPM_SHORT] = durations[0];
+		chip->duration[TPM_MEDIUM] = durations[1];
+		chip->duration[TPM_LONG] = durations[2];
+	}
+
 	/* The Broadcom BCM0102 chipset in a Dell Latitude D820 gets the above
 	 * value wrong and apparently reports msecs rather than usecs. So we
 	 * fix up the resulting too-small TPM_SHORT value to make things work.
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 53c0ea9ec9df..bb1d1ac7081d 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -67,6 +67,8 @@ struct tpm_class_ops {
 	u8 (*status) (struct tpm_chip *chip);
 	void (*update_timeouts)(struct tpm_chip *chip,
 				unsigned long *timeout_cap);
+	void (*update_durations)(struct tpm_chip *chip,
+				 unsigned long *duration_cap);
 	int (*go_idle)(struct tpm_chip *chip);
 	int (*cmd_ready)(struct tpm_chip *chip);
 	int (*request_locality)(struct tpm_chip *chip, int loc);
-- 
2.21.0