linux-kernel - Re: [PATCH v2] tpm2: add longer timeout for verify signature command

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Message-ID: <YKaQxV4wzZ/UYrdu@kernel.org>
Date:   Thu, 20 May 2021 19:39:33 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     amirmizi6@...il.com
Cc:     Eyal.Cohen@...oton.com, peterhuewe@....de, jgg@...pe.ca,
        linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org,
        Dan.Morav@...oton.com, oren.tanami@...oton.com,
        shmulik.hager@...oton.com, amir.mizinski@...oton.com
Subject: Re: [PATCH v2] tpm2: add longer timeout for verify signature command

On Wed, May 19, 2021 at 05:00:59PM +0300, amirmizi6@...il.com wrote:
> From: Amir Mizinski <amirmizi6@...il.com>
> 
> While running a TPM2_CC_VERIFY_SIGNATURE(0x177) operation with RSA 3070-bit

The hexcode for the TPM command is absoulutely irrelevant detail.

AFAIK, 3070-bit does not exist. It's 3072-bit.

> keys the TPM driver fails with the following error:

Empty line here.

> "kernel: [ 2416.187522] tpm tpm0: Operation Timed out"
> 
> Since a) the TPM PC Client specification does not specify a number for

Remove "a)".
> verify signature operation timeout, and b) the duration of

Remove "b)".

> TPM2_CC_VERIFY_SIGNATURE with RSA 3070-bit keys exceeds the current timeout
> of TPM_LONG (2 seconds), it is preferable to pick the longest timeout
> possible.

Empty line here.

> Therefore, set the duration for TPM2_CC_VERIFY_SIGNATUE to TPM_LONG_LONG
> (5 minutes).
> 
Add here:

Link: https://trustedcomputinggroup.org/resource/pc-client-specific-platform-firmware-profile-specification/

> Signed-off-by: Amir Mizinski <amirmizi6@...il.com>


> ---
>  drivers/char/tpm/tpm2-cmd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index 7603295..e71154b 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -87,7 +87,7 @@ static u8 tpm2_ordinal_duration_index(u32 ordinal)
>  		return TPM_MEDIUM;
>  
>  	case TPM2_CC_VERIFY_SIGNATURE:        /* 177 */
> -		return TPM_LONG;
> +		return TPM_LONG_LONG;
>  
>  	case TPM2_CC_PCR_EXTEND:              /* 182 */
>  		return TPM_MEDIUM;
> -- 
> 2.7.4
> 
> 

/Jarkko