[PATCH v4 3/5] 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>
---
Changes in v4:
- remove unnecessary EFIAPI specifier

Changes in v2:
- use strlen instead of sizeof, event log for EV_EFI_ACTION string

  shall not include NUL terminator
 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 6f61e9faac..32cb8d0f1e 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -499,6 +499,7 @@ 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 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 13ab139222..b818cbb540 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -2182,6 +2182,11 @@ 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 ed71337780..8557fce1da 100644
--- a/lib/efi_loader/efi_tcg2.c
+++ b/lib/efi_loader/efi_tcg2.c
@@ -1506,6 +1506,67 @@ efi_status_t 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
+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,
+				 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_FAILED),
+				 (u8 *)EFI_EXIT_BOOT_SERVICES_FAILED);
+
+out:
+	return ret;
+}
+
 /**
  * tcg2_measure_secure_boot_variable() - measure secure boot variables
  *
@@ -1584,6 +1645,7 @@ 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) {
@@ -1608,6 +1670,14 @@ 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