linux-kernel - Re: [PATCH v9 14/19] tpm: Ensure tpm is in known state at startup

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Message-Id: <D1RIB8BHWRC5.3RRW0ZKV3KDVM@kernel.org>
Date: Tue, 04 Jun 2024 23:14:47 +0300
From: "Jarkko Sakkinen" <jarkko@...nel.org>
To: "Ross Philipson" <ross.philipson@...cle.com>,
 <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: <dpsmith@...rtussolutions.com>, <tglx@...utronix.de>,
 <mingo@...hat.com>, <bp@...en8.de>, <hpa@...or.com>,
 <dave.hansen@...ux.intel.com>, <ardb@...nel.org>, <mjg59@...f.ucam.org>,
 <James.Bottomley@...senpartnership.com>, <peterhuewe@....de>,
 <jgg@...pe.ca>, <luto@...capital.net>, <nivedita@...m.mit.edu>,
 <herbert@...dor.apana.org.au>, <davem@...emloft.net>, <corbet@....net>,
 <ebiederm@...ssion.com>, <dwmw2@...radead.org>, <baolu.lu@...ux.intel.com>,
 <kanth.ghatraju@...cle.com>, <andrew.cooper3@...rix.com>,
 <trenchboot-devel@...glegroups.com>
Subject: Re: [PATCH v9 14/19] tpm: Ensure tpm is in known state at startup

On Fri May 31, 2024 at 4:03 AM EEST, Ross Philipson wrote:
> From: "Daniel P. Smith" <dpsmith@...rtussolutions.com>
>
> When tis core initializes, it assumes all localities are closed. There

s/tis_core/tpm_tis_core/

> 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 7c1761bd6000..9fb53bb3e73f 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -1104,7 +1104,7 @@ 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);
> @@ -1166,6 +1166,15 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
>  		goto out_err;
>  	}
>  
> +	/*
> +	 * There are environments, like Intel TXT, that may leave a TPM

What else at this point than Intel TXT reflecting the state of the
mainline?

> +	 * locality open. Close all localities to start from a known state.
> +	 */
> +	for (i = 0; i <= TPM_MAX_LOCALITY; i++) {
> +		if (check_locality(chip, i))
> +			tpm_tis_relinquish_locality(chip, i);
> +	}

To be strict this should be enabled only for x86 platforms.

I.e. should be flagged.

> +
>  	/* 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 c17e4efbb2e5..363f7078c3a9 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;


BR, Jarkko