linux-kernel - [RFC PATCH 3/4] tpm, tpm_tis: allow to set locality to a different value

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Message-ID: <20241102152226.2593598-4-jarkko@kernel.org>
Date: Sat,  2 Nov 2024 17:22:20 +0200
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Peter Huewe <peterhuewe@....de>,
	Jarkko Sakkinen <jarkko@...nel.org>,
	Jason Gunthorpe <jgg@...pe.ca>
Cc: x86@...nel.org,
	"Daniel P. Smith" <dpsmith@...rtussolutions.com>,
	Ross Philipson <ross.philipson@...cle.com>,
	Ard Biesheuvel <ardb@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-integrity@...r.kernel.org (open list:TPM DEVICE DRIVER),
	linux-kernel@...r.kernel.org (open list),
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Stefan Berger <stefanb@...ux.ibm.com>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: [RFC PATCH 3/4] tpm, tpm_tis: allow to set locality to a different value

From: Ross Philipson <ross.philipson@...cle.com>

DRTM needs to be able to set the locality used by kernel. Provide
a one-shot function tpm_chip_set_locality() for the purpose.

Signed-off-by: Ross Philipson <ross.philipson@...cle.com>
Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
---
 drivers/char/tpm/tpm-chip.c     | 33 ++++++++++++++++++++++++++++++++-
 drivers/char/tpm/tpm_tis_core.c |  2 ++
 include/linux/tpm.h             |  4 ++++
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 7df7abaf3e52..ac200514c4d7 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -44,7 +44,7 @@ static int tpm_request_locality(struct tpm_chip *chip)
 	if (!chip->ops->request_locality)
 		return 0;
 
-	rc = chip->ops->request_locality(chip, 0);
+	rc = chip->ops->request_locality(chip, chip->kernel_locality);
 	if (rc < 0)
 		return rc;
 
@@ -374,6 +374,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
 	}
 
 	chip->locality = -1;
+	chip->kernel_locality = 0;
 	return chip;
 
 out:
@@ -689,3 +690,33 @@ void tpm_chip_unregister(struct tpm_chip *chip)
 	tpm_del_char_device(chip);
 }
 EXPORT_SYMBOL_GPL(tpm_chip_unregister);
+
+/**
+ * tpm_chip_set_locality() - Set the TPM locality kernel uses
+ * @chip:	&tpm_chip instance
+ * @locality:   new locality
+ *
+ * This a one-shot function. Returns zero or POSIX error on failure.
+ */
+int tpm_chip_set_locality(struct tpm_chip *chip, u8 locality)
+{
+	int ret;
+
+	if (locality < 0 || locality >= TPM_MAX_LOCALITY)
+		return -EINVAL;
+
+	ret = tpm_try_get_ops(chip);
+	if (ret)
+		return ret;
+
+	if (!(chip->flags & TPM_CHIP_FLAG_SET_LOCALITY_ENABLED)) {
+		tpm_put_ops(chip);
+		return -EINVAL;
+	}
+
+	chip->kernel_locality = locality;
+	chip->flags &= ~TPM_CHIP_FLAG_SET_LOCALITY_ENABLED;
+	tpm_put_ops(chip);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tpm_chip_set_locality);
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index c86100ad743a..b85677eccc86 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -1114,6 +1114,8 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 	if (IS_ERR(chip))
 		return PTR_ERR(chip);
 
+	chip->flags |= TPM_CHIP_FLAG_SET_LOCALITY_ENABLED;
+
 #ifdef CONFIG_ACPI
 	chip->acpi_dev_handle = acpi_dev_handle;
 #endif
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 0708f744c803..af88161c1316 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -207,6 +207,8 @@ struct tpm_chip {
 
 	/* active locality */
 	int locality;
+	/* the locality used by kernel */
+	u8 kernel_locality;
 
 #ifdef CONFIG_TCG_TPM2_HMAC
 	/* details for communication security via sessions */
@@ -354,6 +356,7 @@ enum tpm_chip_flags {
 	TPM_CHIP_FLAG_SUSPENDED			= BIT(8),
 	TPM_CHIP_FLAG_HWRNG_DISABLED		= BIT(9),
 	TPM_CHIP_FLAG_DISABLE			= BIT(10),
+	TPM_CHIP_FLAG_SET_LOCALITY_ENABLED	= BIT(11),
 };
 
 #define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)
@@ -446,6 +449,7 @@ static inline u32 tpm2_rc_value(u32 rc)
 extern int tpm_is_tpm2(struct tpm_chip *chip);
 extern __must_check int tpm_try_get_ops(struct tpm_chip *chip);
 extern void tpm_put_ops(struct tpm_chip *chip);
+int tpm_chip_set_locality(struct tpm_chip *chip, u8 locality);
 extern ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
 				size_t min_rsp_body_length, const char *desc);
 extern int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
-- 
2.47.0