linux-kernel - [PATCH v10 15/20] tpm: Ensure tpm is in known state at startup

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Message-Id: <20240826223835.3928819-16-ross.philipson@oracle.com>
Date: Mon, 26 Aug 2024 15:38:30 -0700
From: Ross Philipson <ross.philipson@...cle.com>
To: linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-integrity@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-crypto@...r.kernel.org, kexec@...ts.infradead.org,
        linux-efi@...r.kernel.org, iommu@...ts.linux-foundation.org
Cc: ross.philipson@...cle.com, dpsmith@...rtussolutions.com,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
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        trenchboot-devel@...glegroups.com
Subject: [PATCH v10 15/20] tpm: Ensure tpm is in known state at startup

From: "Daniel P. Smith" <dpsmith@...rtussolutions.com>

When tis_tis_core initializes, it assumes all localities are closed. There
are cases when this may not be the case. This commit addresses this by
ensuring all localities are closed before initializing begins.

Signed-off-by: Daniel P. Smith <dpsmith@...rtussolutions.com>
Signed-off-by: Ross Philipson <ross.philipson@...cle.com>
---
 drivers/char/tpm/tpm_tis_core.c | 11 ++++++++++-
 include/linux/tpm.h             |  6 ++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index a6967f312837..22ebf679ea69 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -1107,7 +1107,7 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 	u32 intmask;
 	u32 clkrun_val;
 	u8 rid;
-	int rc, probe;
+	int rc, probe, i;
 	struct tpm_chip *chip;
 
 	chip = tpmm_chip_alloc(dev, &tpm_tis);
@@ -1169,6 +1169,15 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 		goto out_err;
 	}
 
+	/*
+	 * There are environments, for example, those that comply with the TCG D-RTM
+	 * specification that requires the TPM to be left in Locality 2.
+	 */
+	for (i = 0; i <= TPM_MAX_LOCALITY; i++) {
+		if (check_locality(chip, i))
+			tpm_tis_relinquish_locality(chip, i);
+	}
+
 	/* Take control of the TPM's interrupt hardware and shut it off */
 	rc = tpm_tis_read32(priv, TPM_INT_ENABLE(priv->locality), &intmask);
 	if (rc < 0)
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index e93ee8d936a9..98f2c7c1c52e 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -147,6 +147,12 @@ struct tpm_chip_seqops {
  */
 #define TPM2_MAX_CONTEXT_SIZE 4096
 
+/*
+ * The maximum locality (0 - 4) for a TPM, as defined in section 3.2 of the
+ * Client Platform Profile Specification.
+ */
+#define TPM_MAX_LOCALITY		4
+
 struct tpm_chip {
 	struct device dev;
 	struct device devs;
-- 
2.39.3