linux-kernel - Re: [PATCH] efi/tpm: Differentiate missing and invalid final event log table.

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Date:   Fri, 9 Jul 2021 19:38:46 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Michal Suchanek <msuchanek@...e.de>
Cc:     linux-integrity@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Loïc Yhuel <loic.yhuel@...il.com>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        Matthew Garrett <mjg59@...gle.com>, linux-efi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] efi/tpm: Differentiate missing and invalid final event
 log table.

On Thu, Jul 08, 2021 at 11:46:54AM +0200, Michal Suchanek wrote:
> Missing TPM final event log table is not a firmware bug.
> 
> Clearly if providing event log in the old format makes the final event
> log invalid it should not be provided at least in that case.
> 
> Fixes: b4f1874c6216 ("tpm: check event log version before reading final events")
> Signed-off-by: Michal Suchanek <msuchanek@...e.de>
> ---
>  drivers/firmware/efi/tpm.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c
> index c1955d320fec..8f665678e9e3 100644
> --- a/drivers/firmware/efi/tpm.c
> +++ b/drivers/firmware/efi/tpm.c
> @@ -62,9 +62,11 @@ int __init efi_tpm_eventlog_init(void)
>  	tbl_size = sizeof(*log_tbl) + log_tbl->size;
>  	memblock_reserve(efi.tpm_log, tbl_size);
>  
> -	if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR ||
> -	    log_tbl->version != EFI_TCG2_EVENT_LOG_FORMAT_TCG_2) {
> -		pr_warn(FW_BUG "TPM Final Events table missing or invalid\n");
> +	if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR) {
> +		pr_info("TPM Final Events table not present\n");
> +		goto out;
> +	} else if (log_tbl->version != EFI_TCG2_EVENT_LOG_FORMAT_TCG_2) {
> +		pr_warn(FW_BUG "TPM Final Events table invalid\n");
>  		goto out;
>  	}
>  
> -- 
> 2.26.2
> 
> 

Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>

/Jarkko