[PATCH 4/5] efi_loader: add ExitBootServices() measurement

[Masahisa Kojima]

TCG PC Client PFP spec requires to measure
"Exit Boot Services Invocation" if ExitBootServices() is invoked.
Depending upon the return code from the ExitBootServices() call,
"Exit Boot Services Returned with Success" or "Exit Boot Services
Returned with Failure" is also measured.

Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
---
 include/efi_loader.h          |  1 +
 lib/efi_loader/efi_boottime.c |  5 +++
 lib/efi_loader/efi_tcg2.c     | 70 +++++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+)

diff --git a/include/efi_loader.h b/include/efi_loader.h
index 281ffff30f..e9bd1aac08 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -407,6 +407,7 @@ efi_status_t efi_run_image(void *source_buffer, efi_uintn_t source_size);
 efi_status_t efi_init_variables(void);
 /* Notify ExitBootServices() is called */
 void efi_variables_boot_exit_notify(void);
+efi_status_t efi_tcg2_notify_exit_boot_services_failed(void);
 /* Measure efi application invocation */
 efi_status_t EFIAPI efi_tcg2_measure_efi_app_invocation(void);
 /* Measure efi application exit */
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 2914800c56..6e07ef65bc 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -2181,6 +2181,11 @@ static efi_status_t EFIAPI efi_exit_boot_services(efi_handle_t image_handle,
 	efi_set_watchdog(0);
 	WATCHDOG_RESET();
 out:
+	if (ret != EFI_SUCCESS) {
+		if (IS_ENABLED(CONFIG_EFI_TCG2_PROTOCOL))
+			efi_tcg2_notify_exit_boot_services_failed();
+	}
+
 	return EFI_EXIT(ret);
 }
 
diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c
index 6e903e3cb3..823abd8217 100644
--- a/lib/efi_loader/efi_tcg2.c
+++ b/lib/efi_loader/efi_tcg2.c
@@ -1506,6 +1506,67 @@ efi_status_t EFIAPI efi_tcg2_measure_efi_app_exit(void)
 	return ret;
 }
 
+/**
+ * efi_tcg2_notify_exit_boot_services() - ExitBootService callback
+ *
+ * @event:	callback event
+ * @context:	callback context
+ */
+static void EFIAPI
+efi_tcg2_notify_exit_boot_services(struct efi_event *event, void *context)
+{
+	efi_status_t ret;
+	struct udevice *dev;
+
+	EFI_ENTRY("%p, %p", event, context);
+
+	ret = platform_get_tpm2_device(&dev);
+	if (ret != EFI_SUCCESS)
+		goto out;
+
+	ret = tcg2_measure_event(dev, 5, EV_EFI_ACTION,
+				 strlen(EFI_EXIT_BOOT_SERVICES_INVOCATION),
+				 (u8 *)EFI_EXIT_BOOT_SERVICES_INVOCATION);
+	if (ret != EFI_SUCCESS)
+		goto out;
+
+	ret = tcg2_measure_event(dev, 5, EV_EFI_ACTION,
+				 strlen(EFI_EXIT_BOOT_SERVICES_SUCCEEDED),
+				 (u8 *)EFI_EXIT_BOOT_SERVICES_SUCCEEDED);
+
+out:
+	EFI_EXIT(ret);
+}
+
+/**
+ * efi_tcg2_notify_exit_boot_services_failed()
+ *  - notify ExitBootServices() is failed
+ *
+ * Return:	status code
+ */
+efi_status_t efi_tcg2_notify_exit_boot_services_failed(void)
+{
+	struct udevice *dev;
+	efi_status_t ret;
+
+	ret = platform_get_tpm2_device(&dev);
+	if (ret != EFI_SUCCESS)
+		goto out;
+
+	ret = tcg2_measure_event(dev, 5, EV_EFI_ACTION,
+				 sizeof(EFI_EXIT_BOOT_SERVICES_INVOCATION),
+				 (u8 *)EFI_EXIT_BOOT_SERVICES_INVOCATION);
+	if (ret != EFI_SUCCESS)
+		goto out;
+
+	ret = tcg2_measure_event(dev, 5, EV_EFI_ACTION,
+				 sizeof(EFI_EXIT_BOOT_SERVICES_FAILED),
+				 (u8 *)EFI_EXIT_BOOT_SERVICES_FAILED);
+
+out:
+	return ret;
+}
+
 /**
  * tcg2_measure_secure_boot_variable() - measure secure boot variables
  *
@@ -1556,6 +1617,7 @@ efi_status_t efi_tcg2_register(void)
 {
 	efi_status_t ret = EFI_SUCCESS;
 	struct udevice *dev;
+	struct efi_event *event;
 
 	ret = platform_get_tpm2_device(&dev);
 	if (ret != EFI_SUCCESS) {
@@ -1580,6 +1642,14 @@ efi_status_t efi_tcg2_register(void)
 		goto fail;
 	}
 
+	ret = efi_create_event(EVT_SIGNAL_EXIT_BOOT_SERVICES, TPL_CALLBACK,
+			       efi_tcg2_notify_exit_boot_services, NULL,
+			       NULL, &event);
+	if (ret != EFI_SUCCESS) {
+		tcg2_uninit();
+		goto fail;
+	}
+
 	ret = tcg2_measure_secure_boot_variable(dev);
 	if (ret != EFI_SUCCESS) {
 		tcg2_uninit();
-- 
2.17.1