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Fix TPM 1.2 resume

PATCH In review Jarkko Sakkinen 2 participants 5 messages May 2, 2023 – May 10, 2023

Subsystems (3)
Stable branch Keys-trusted TPM device driver
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Jarkko Sakkinen

author maintainer
#0 lore raw

v2 cover Fix TPM 1.2 resume

During TPM 1.2 resume, the first PCR read operation used inside tpm1_do_selftest() fails. Fix the bugs preventing resume from working.

v2:
* Added Jerry's reviewed-by's.
* Rebased to 865fdb08197e ("Merge tag 'input-for-v6.4-rc0' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input").
* Mirrored patches to linux-next.

Cc Vlastimil Babka <[email protected]>
Cc Jason A. Donenfeld <[email protected]>
Cc Jason Gunthorpe <[email protected]>
Cc Jerry Snitselaar <[email protected]>
Link https://lore.kernel.org/linux-integrity/CS6UJMSTVA4L.FRQ5VL1I1EF4@suppilovahvero/T/#m236d62184229cc035605143fde10933bcde60065 open here

Jarkko Sakkinen (2):
tpm_tis: Use tpm_chip_{start,stop} decoration inside tpm_tis_resume
tpm: Prevent hwrng from activating during resume

 drivers/char/tpm/tpm-chip.c      |  4 +++
 drivers/char/tpm/tpm-interface.c | 10 ++++++++
 drivers/char/tpm/tpm_tis_core.c  | 43 ++++++++++++++------------------
 include/linux/tpm.h              |  1 +
 4 files changed, 34 insertions(+), 24 deletions(-)
Signature · 1 line
2.39.2
author maintainer
#1 lore raw

PATCH v2 1/2 tpm_tis: Use tpm_chip_{start,stop} decoration inside tpm_tis_resume

Before sending a TPM command, CLKRUN protocol must be disabled. This is not done in the case of tpm1_do_selftest() call site inside tpm_tis_resume().

Address this by decorating the calls with tpm_chip_{start,stop}, which should be always used to arm and disarm the TPM chip for transmission.

Finally, move the call to the main TPM driver callback as the last step because it should arm the chip by itself, if it needs that type of functionality.

Cc [email protected]
Reported-by Jason A. Donenfeld <[email protected]>
Closes https://lore.kernel.org/linux-integrity/CS68AWILHXS4.3M36M1EKZLUMS@suppilovahvero/ open here
Fixes a3fbfae82b4c ("tpm: take TPM chip power gating out of tpm_transmit()")
Reviewed-by Jerry Snitselaar <[email protected]>
Signed-off-by Jarkko Sakkinen <[email protected]>
---
 drivers/char/tpm/tpm_tis_core.c | 43 +++++++++++++++------------------
 1 file changed, 19 insertions(+), 24 deletions(-)
drivers/char/tpm/tpm_tis_core.c +19 -24
index 02945d53fcef..558144fa707a 100644
@@ -1209,25 +1209,20 @@ static void tpm_tis_reenable_interrupts(struct tpm_chip *chip)
 	u32 intmask;
 	int rc;
 
-	if (chip->ops->clk_enable != NULL)
-		chip->ops->clk_enable(chip, true);
-
-	/* reenable interrupts that device may have lost or
-	 * BIOS/firmware may have disabled
+	/*
+	 * Re-enable interrupts that device may have lost or BIOS/firmware may
+	 * have disabled.
 	 */
 	rc = tpm_tis_write8(priv, TPM_INT_VECTOR(priv->locality), priv->irq);
-	if (rc < 0)
-		goto out;
+	if (rc < 0) {
+		dev_err(&chip->dev, "Setting IRQ failed.\n");
+		return;
+	}
 
 	intmask = priv->int_mask | TPM_GLOBAL_INT_ENABLE;
-
-	tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
-
-out:
-	if (chip->ops->clk_enable != NULL)
-		chip->ops->clk_enable(chip, false);
-
-	return;
+	rc = tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
+	if (rc < 0)
+		dev_err(&chip->dev, "Enabling interrupts failed.\n");
 }
 
 int tpm_tis_resume(struct device *dev)

@@ -1235,27 +1230,27 @@ int tpm_tis_resume(struct device *dev)
 	struct tpm_chip *chip = dev_get_drvdata(dev);
 	int ret;
 
-	ret = tpm_tis_request_locality(chip, 0);
-	if (ret < 0)
+	ret = tpm_chip_start(chip);
+	if (ret)
 		return ret;
 
 	if (chip->flags & TPM_CHIP_FLAG_IRQ)
 		tpm_tis_reenable_interrupts(chip);
 
-	ret = tpm_pm_resume(dev);
-	if (ret)
-		goto out;
-
 	/*
 	 * TPM 1.2 requires self-test on resume. This function actually returns
 	 * an error code but for unknown reason it isn't handled.
 	 */
 	if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
 		tpm1_do_selftest(chip);
-out:
-	tpm_tis_relinquish_locality(chip, 0);
 
-	return ret;
+	tpm_chip_stop(chip);
+
+	ret = tpm_pm_resume(dev);
+	if (ret)
+		return ret;
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(tpm_tis_resume);
 #endif
Signature · 1 line
2.39.2
author maintainer
#2 lore raw

PATCH v2 2/2 tpm: Prevent hwrng from activating during resume

In reply to Jarkko Sakkinen

Set TPM_CHIP_FLAG_SUSPENDED in tpm_pm_suspend() and reset in tpm_pm_resume(). While the flag is set, tpm_hwrng() gives back zero bytes. This prevents hwrng from racing during resume.

Cc [email protected]
Fixes 6e592a065d51 ("tpm: Move Linux RNG connection to hwrng")
Reviewed-by Jerry Snitselaar <[email protected]>
Signed-off-by Jarkko Sakkinen <[email protected]>
---
 drivers/char/tpm/tpm-chip.c      |  4 ++++
 drivers/char/tpm/tpm-interface.c | 10 ++++++++++
 include/linux/tpm.h              |  1 +
 3 files changed, 15 insertions(+)
drivers/char/tpm/tpm-chip.c +4 -0
index c10a4aa97373..cd48033b804a 100644
@@ -571,6 +571,10 @@ static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
 {
 	struct tpm_chip *chip = container_of(rng, struct tpm_chip, hwrng);
 
+	/* Give back zero bytes, as TPM chip has not yet fully resumed: */
+	if (chip->flags & TPM_CHIP_FLAG_SUSPENDED)
+		return 0;
+
 	return tpm_get_random(chip, data, max);
 }
drivers/char/tpm/tpm-interface.c +10 -0
index 4463d0018290..586ca10b0d72 100644
@@ -412,6 +412,8 @@ int tpm_pm_suspend(struct device *dev)
 	}
 
 suspended:
+	chip->flags |= TPM_CHIP_FLAG_SUSPENDED;
+
 	if (rc)
 		dev_err(dev, "Ignoring error %d while suspending\n", rc);
 	return 0;

@@ -429,6 +431,14 @@ int tpm_pm_resume(struct device *dev)
 	if (chip == NULL)
 		return -ENODEV;
 
+	chip->flags &= ~TPM_CHIP_FLAG_SUSPENDED;
+
+	/*
+	 * Guarantee that SUSPENDED is written last, so that hwrng does not
+	 * activate before the chip has been fully resumed.
+	 */
+	wmb();
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tpm_pm_resume);
include/linux/tpm.h +1 -0
index 77693389c3f9..6a1e8f157255 100644
@@ -282,6 +282,7 @@ enum tpm_chip_flags {
 	TPM_CHIP_FLAG_ALWAYS_POWERED		= BIT(5),
 	TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED	= BIT(6),
 	TPM_CHIP_FLAG_FIRMWARE_UPGRADE		= BIT(7),
+	TPM_CHIP_FLAG_SUSPENDED			= BIT(8),
 };
 
 #define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)
Signature · 1 line
2.39.2
#3 lore raw
In reply to Jarkko Sakkinen
Quoted 2 lines · Jarkko Sakkinen

During TPM 1.2 resume, the first PCR read operation used inside tpm1_do_selftest() fails. Fix the bugs preventing resume from working.

Thanks for fixing this, unfortunately I can no longer test the fix as I've got a new laptop since when I was hitting the bug on the older one.

Vlastimil

Quoted 21 lines

v2:
* Added Jerry's reviewed-by's.
* Rebased to 865fdb08197e ("Merge tag 'input-for-v6.4-rc0' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input").
* Mirrored patches to linux-next.

Cc Vlastimil Babka <[email protected]>
Cc Jason A. Donenfeld <[email protected]>
Cc Jason Gunthorpe <[email protected]>
Cc Jerry Snitselaar <[email protected]>
Link https://lore.kernel.org/linux-integrity/CS6UJMSTVA4L.FRQ5VL1I1EF4@suppilovahvero/T/#m236d62184229cc035605143fde10933bcde60065 open here

Jarkko Sakkinen (2):
tpm_tis: Use tpm_chip_{start,stop} decoration inside tpm_tis_resume
tpm: Prevent hwrng from activating during resume

 drivers/char/tpm/tpm-chip.c      |  4 +++
 drivers/char/tpm/tpm-interface.c | 10 ++++++++
 drivers/char/tpm/tpm_tis_core.c  | 43 ++++++++++++++------------------
 include/linux/tpm.h              |  1 +
 4 files changed, 34 insertions(+), 24 deletions(-)
author maintainer
#4 lore raw
Quoted 6 lines · Vlastimil Babka
Quoted 2 lines · Jarkko Sakkinen

During TPM 1.2 resume, the first PCR read operation used inside tpm1_do_selftest() fails. Fix the bugs preventing resume from working.

Thanks for fixing this, unfortunately I can no longer test the fix as I've got a new laptop since when I was hitting the bug on the older one.

I don't think these fixed make things worse, and I could reproduce the bug locally, so I'll put them to my PR :-)

BR, Jarkko