linux-kernel - Re: [PATCH] tpm: add vendor flag to command code validation

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Message-ID: <Y+WUqcNTc8t0KIyD@kernel.org>
Date:   Fri, 10 Feb 2023 02:49:45 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Julien Gomes <julien@...sta.com>
Cc:     linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org,
        jgg@...pe.ca, peterhuewe@....de
Subject: Re: [PATCH] tpm: add vendor flag to command code validation

On Wed, Feb 08, 2023 at 11:58:36AM -0800, Julien Gomes wrote:
> Some TPM 2.0 devices have support for additional commands which are not
> part of the TPM 2.0 specifications.
> These commands are identified with bit 29 of the 32 bits command codes.
> Contrarily to other fields of the TPMA_CC spec structure used to list
> available commands, the Vendor flag also has to be present in the
> command code itself (TPM_CC) when called.
> 
> Add this flag to tpm_find_cc() mask to prevent blocking vendor command
> codes that can actually be supported by the underlying TPM device.
> 
> Signed-off-by: Julien Gomes <julien@...sta.com>
> ---
>  drivers/char/tpm/tpm2-cmd.c | 4 +++-
>  include/linux/tpm.h         | 1 +
>  2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index 65d03867e114..93545be190a5 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -777,10 +777,12 @@ int tpm2_auto_startup(struct tpm_chip *chip)
>  
>  int tpm2_find_cc(struct tpm_chip *chip, u32 cc)
>  {
> +	u32 cc_mask;
>  	int i;
>  
> +	cc_mask = 1 << TPM2_CC_ATTR_VENDOR | GENMASK(15, 0);
>  	for (i = 0; i < chip->nr_commands; i++)
> -		if (cc == (chip->cc_attrs_tbl[i] & GENMASK(15, 0)))
> +		if (cc == (chip->cc_attrs_tbl[i] & cc_mask))
>  			return i;
>  
>  	return -1;
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index dfeb25a0362d..4dc97b9f65fb 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -265,6 +265,7 @@ enum tpm2_startup_types {
>  enum tpm2_cc_attrs {
>  	TPM2_CC_ATTR_CHANDLES	= 25,
>  	TPM2_CC_ATTR_RHANDLE	= 28,
> +	TPM2_CC_ATTR_VENDOR	= 29,
>  };
>  
>  #define TPM_VID_INTEL    0x8086
> -- 
> 2.39.1
> 

Just checking: did you run testing/selftests/tpm2?

BR, Jarkko