Re: [PATCH v4] tpm: Parse event log from TPM2 ACPI table

[Jerry Snitselaar]

On Fri Aug 30 19, Jordan Hand wrote:
> For systems with a TPM2 chip which use ACPI to expose event logs, retrieve the
> crypto-agile event log from the TPM2 ACPI table. The TPM2 table is defined
> in section 7.3 of the TCG ACPI Specification (see link).
>
> The TPM2 table is used by SeaBIOS in place of the TCPA table when the system's
> TPM is version 2.0 to denote (among other metadata) the location of the
> crypto-agile log.
>
> Link: https://trustedcomputinggroup.org/resource/tcg-acpi-specification/
> Signed-off-by: Jordan Hand <jorhand@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/char/tpm/eventlog/acpi.c | 60 ++++++++++++++++++++++----------
> 1 file changed, 41 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c
> index 63ada5e53f13..38a8bcec1dd5 100644
> --- a/drivers/char/tpm/eventlog/acpi.c
> +++ b/drivers/char/tpm/eventlog/acpi.c
> @@ -41,17 +41,23 @@ struct acpi_tcpa {
> 	};
> };
>
> +/* If an event log is present, the TPM2 ACPI table will contain the full
> + * trailer
> + */
> +
> /* read binary bios log */
> int tpm_read_log_acpi(struct tpm_chip *chip)
> {
> -	struct acpi_tcpa *buff;
> +	struct acpi_table_header *buff;
> +	struct acpi_tcpa *tcpa;
> +	struct acpi_tpm2_trailer *tpm2_trailer;
> 	acpi_status status;
> 	void __iomem *virt;
> 	u64 len, start;
> +	int log_type;
> 	struct tpm_bios_log *log;
> -
> -	if (chip->flags & TPM_CHIP_FLAG_TPM2)
> -		return -ENODEV;
> +	bool is_tpm2 = chip->flags & TPM_CHIP_FLAG_TPM2;
> +	acpi_string table_sig;
>
> 	log = &chip->log;
>
> @@ -61,26 +67,42 @@ 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);
> +	/* Find TCPA or TPM2 entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
> +	table_sig = is_tpm2 ? ACPI_SIG_TPM2 : ACPI_SIG_TCPA;
> +	status = acpi_get_table(table_sig, 1, &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 (!is_tpm2) {
> +		tcpa = (struct acpi_tcpa *)buff;
> +		switch (tcpa->platform_class) {
> +		case BIOS_SERVER:
> +			len = tcpa->server.log_max_len;
> +			start = tcpa->server.log_start_addr;
> +			break;
> +		case BIOS_CLIENT:
> +		default:
> +			len = tcpa->client.log_max_len;
> +			start = tcpa->client.log_start_addr;
> +			break;
> +		}
> +		log_type = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
> +	} else if (buff->length ==
> +		   sizeof(struct acpi_table_tpm2) +
> +		   sizeof(struct acpi_tpm2_trailer)) {
> +		tpm2_trailer = (struct acpi_tpm2_trailer *)buff;
> +
> +		len = tpm2_trailer.minimum_log_length;
> +		start = tpm2_trailer.log_address;

Are your builds not failing here? Both v3 and v4 have this.

> +		log_type = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2;
> +	} else {
> +		return -ENODEV;
> 	}
> +
> 	if (!len) {
> -		dev_warn(&chip->dev, "%s: TCPA log area empty\n", __func__);
> +		dev_warn(&chip->dev, "%s: %s log area empty\n",
> +			 __func__, table_sig);
> 		return -EIO;
> 	}
>
> @@ -98,7 +120,7 @@ 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 log_type;
>
> err:
> 	kfree(log->bios_event_log);
> --
> 2.20.1