linux-kernel - Re: [PATCH v7 2/2] tpm: Add support for event log pointer found in TPM2 ACPI table

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Date:   Fri, 26 Jun 2020 16:27:06 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Stefan Berger <stefanb@...ux.vnet.ibm.com>
Cc:     linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, linux-security-module@...r.kernel.org,
        Stefan Berger <stefanb@...ux.ibm.com>
Subject: Re: [PATCH v7 2/2] tpm: Add support for event log pointer found in
 TPM2 ACPI table

On Thu, Jun 25, 2020 at 05:50:00PM -0400, Stefan Berger wrote:
> From: Stefan Berger <stefanb@...ux.ibm.com>
> 
> In case a TPM2 is attached, search for a TPM2 ACPI table when trying
> to get the event log from ACPI. If one is found, use it to get the
> start and length of the log area. This allows non-UEFI systems, such
> as SeaBIOS, to pass an event log when using a TPM2.
> 
> Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
> ---
>  drivers/char/tpm/eventlog/acpi.c | 62 +++++++++++++++++++++-----------
>  1 file changed, 41 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c
> index 63ada5e53f13..e2258cfa6cb1 100644
> --- a/drivers/char/tpm/eventlog/acpi.c
> +++ b/drivers/char/tpm/eventlog/acpi.c
> @@ -49,9 +49,9 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
>  	void __iomem *virt;
>  	u64 len, start;
>  	struct tpm_bios_log *log;
> -
> -	if (chip->flags & TPM_CHIP_FLAG_TPM2)
> -		return -ENODEV;
> +	struct acpi_table_tpm2 *tbl;
> +	struct acpi_tpm2_phy *t2phy;
> +	int format;
>  
>  	log = &chip->log;
>  
> @@ -61,23 +61,43 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
>  	if (!chip->acpi_dev_handle)
>  		return -ENODEV;
>  
> -	/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
> -	status = acpi_get_table(ACPI_SIG_TCPA, 1,
> -				(struct acpi_table_header **)&buff);
> -
> -	if (ACPI_FAILURE(status))
> -		return -ENODEV;
> -
> -	switch(buff->platform_class) {
> -	case BIOS_SERVER:
> -		len = buff->server.log_max_len;
> -		start = buff->server.log_start_addr;
> -		break;
> -	case BIOS_CLIENT:
> -	default:
> -		len = buff->client.log_max_len;
> -		start = buff->client.log_start_addr;
> -		break;
> +	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
> +		status = acpi_get_table("TPM2", 1,
> +					(struct acpi_table_header **)&tbl);
> +		if (ACPI_FAILURE(status))
> +			return -ENODEV;
> +
> +		if (tbl->header.length <
> +				sizeof(*tbl) + sizeof(struct acpi_tpm2_phy))
> +			return -ENODEV;
> +
> +		t2phy = (void *)tbl + sizeof(*tbl);
> +		len = t2phy->log_area_minimum_length;
> +
> +		start = t2phy->log_area_start_address;
> +		if (!start || !len)
> +			return -ENODEV;
> +
> +		format = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2;
> +	} else {
> +		/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
> +		status = acpi_get_table(ACPI_SIG_TCPA, 1,
> +					(struct acpi_table_header **)&buff);
> +		if (ACPI_FAILURE(status))
> +			return -ENODEV;
> +
> +		switch (buff->platform_class) {
> +		case BIOS_SERVER:
> +			len = buff->server.log_max_len;
> +			start = buff->server.log_start_addr;
> +			break;
> +		case BIOS_CLIENT:
> +		default:
> +			len = buff->client.log_max_len;
> +			start = buff->client.log_start_addr;
> +			break;
> +		}

Empty line as in the first branch after the conditional statement.

> +		format = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
>  	}
>  	if (!len) {
>  		dev_warn(&chip->dev, "%s: TCPA log area empty\n", __func__);
> @@ -98,7 +118,7 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
>  	memcpy_fromio(log->bios_event_log, virt, len);
>  
>  	acpi_os_unmap_iomem(virt, len);
> -	return EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
> +	return format;
>  
>  err:
>  	kfree(log->bios_event_log);
> -- 
> 2.26.2
> 

/Jarkko