[PATCH v8 0/2] tpm2: Make TPM2 logs accessible for non-UEFI firmware

[PATCH v8 0/2] tpm2: Make TPM2 logs accessible for non-UEFI firmware

[Stefan Berger]

From: Stefan Berger <stefanb@linux.ibm.com>

This series of patches adds an optional extensions for the TPM2 ACPI table
with additional fields found in the TPM2 TCG ACPI specification (reference
is in the patch) that allow access to the log's address and its size. We
then modify the code that so far only enables access to a TPM 1.2's log for
a TPM2 as well. This then enables access to the TPM2's log on non-UEFI
system that for example run SeaBIOS.

   Stefan

v7->v8:
 - Added empty line.

v6->v7:
 - Added empty lines and R-b.

v5->v6:
 - Moved extensions of TPM2 table into acpi_tpm2_phy.

v4->v5:
 - Added R-bs and A-bs.

v3->v4:
  - Repost as one series

v2->v3:
  - Split the series into two separate patches
  - Added comments to ACPI table fields
  - Added check for null pointer to log area and zero log size

v1->v2:
  - Repost of the series


Stefan Berger (2):
  acpi: Extend TPM2 ACPI table with missing log fields
  tpm: Add support for event log pointer found in TPM2 ACPI table

 drivers/char/tpm/eventlog/acpi.c | 63 +++++++++++++++++++++-----------
 include/acpi/actbl3.h            |  7 ++++
 2 files changed, 49 insertions(+), 21 deletions(-)

-- 
2.26.2

[PATCH v8 1/2] acpi: Extend TPM2 ACPI table with missing log fields

[Stefan Berger]

From: Stefan Berger <stefanb@linux.ibm.com>

Recent extensions of the TPM2 ACPI table added 3 more fields
including 12 bytes of start method specific parameters and Log Area
Minimum Length (u32) and Log Area Start Address (u64). So, we define
a new structure acpi_tpm2_phy that holds these optional new fields.
The new fields allow non-UEFI systems to access the TPM2's log.

The specification that has the new fields is the following:
  TCG ACPI Specification
  Family "1.2" and "2.0"
  Version 1.2, Revision 8

https://trustedcomputinggroup.org/wp-content/uploads/TCG_ACPIGeneralSpecification_v1.20_r8.pdf

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 include/acpi/actbl3.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/acpi/actbl3.h b/include/acpi/actbl3.h
index b0b163b9efc6..bdcac69fa6bd 100644
--- a/include/acpi/actbl3.h
+++ b/include/acpi/actbl3.h
@@ -415,6 +415,13 @@ struct acpi_table_tpm2 {
 	/* Platform-specific data follows */
 };
 
+/* Optional trailer for revision 4 holding platform-specific data */
+struct acpi_tpm2_phy {
+	u8  start_method_specific[12];
+	u32 log_area_minimum_length;
+	u64 log_area_start_address;
+};
+
 /* Values for start_method above */
 
 #define ACPI_TPM2_NOT_ALLOWED                       0
-- 
2.26.2

[PATCH v8 2/2] tpm: Add support for event log pointer found in TPM2 ACPI table

[Stefan Berger]

From: Stefan Berger <stefanb@linux.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@linux.ibm.com>
---
 drivers/char/tpm/eventlog/acpi.c | 63 +++++++++++++++++++++-----------
 1 file changed, 42 insertions(+), 21 deletions(-)

diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c
index 63ada5e53f13..51312c460335 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 +61,44 @@ 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;
+		}
+
+		format = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
 	}
 	if (!len) {
 		dev_warn(&chip->dev, "%s: TCPA log area empty\n", __func__);
@@ -98,7 +119,7 @@ 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

Re: [PATCH v8 2/2] tpm: Add support for event log pointer found in TPM2 ACPI table

[Jarkko Sakkinen]

On Fri, Jun 26, 2020 at 11:39:48AM -0400, Stefan Berger wrote:
> From: Stefan Berger <stefanb@linux.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@linux.ibm.com>
> ---
>  drivers/char/tpm/eventlog/acpi.c | 63 +++++++++++++++++++++-----------
>  1 file changed, 42 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c
> index 63ada5e53f13..51312c460335 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;

This is a rather cryptic variable name. Should be either 'phy' or
'tpm2_phy' (I don't care that much which one). Did not spot this
earlier.

/Jarkko