Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Stefan Berger <stefanb@linux.vnet.ibm.com>
To:     linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
        jarkko.sakkinen@linux.intel.com, linux-acpi@vger.kernel.org,
        linux-security-module@vger.kernel.org
Cc:     Stefan Berger <stefanb@linux.ibm.com>
Subject: [PATCH v7 2/2] tpm: Add support for event log pointer found in TPM2 ACPI table
Date:   Thu, 25 Jun 2020 17:50:00 -0400
Message-Id: <20200625215000.2052086-3-stefanb@linux.vnet.ibm.com>
In-Reply-To: <20200625215000.2052086-1-stefanb@linux.vnet.ibm.com>
References: <20200625215000.2052086-1-stefanb@linux.vnet.ibm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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 | 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;
+		}
+		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