[PATCH v2 3/3] efi_loader: correctly handle no tpm device error

[Masahisa Kojima]

When the TCG2 protocol is installed in efi_tcg2_register(),
TPM2 device must be present.
tcg2_measure_pe_image() expects that TCP2 protocol is installed
and TPM device is available. If TCG2 Protocol is installed but
TPM device is not found, tcg2_measure_pe_image() returns
EFI_SECURITY_VIOLATION and efi_load_image() ends with failure.

The same error handling is applied to
efi_tcg2_measure_efi_app_invocation().

Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
---

Changes in v2:
- EFI_SECURITY_VIOLATION is returned in
  efi_tcg2_measure_efi_app_invocation()

 lib/efi_loader/efi_boottime.c     |  9 ++++++---
 lib/efi_loader/efi_image_loader.c | 13 ++++++++++---
 lib/efi_loader/efi_tcg2.c         |  4 ++--
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 8492b732f3..20b69699fe 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -3016,9 +3016,12 @@ efi_status_t EFIAPI efi_start_image(efi_handle_t image_handle,
 	if (IS_ENABLED(CONFIG_EFI_TCG2_PROTOCOL)) {
 		if (image_obj->image_type == IMAGE_SUBSYSTEM_EFI_APPLICATION) {
 			ret = efi_tcg2_measure_efi_app_invocation(image_obj);
-			if (ret != EFI_SUCCESS) {
-				log_warning("tcg2 measurement fails(0x%lx)\n",
-					    ret);
+			if (ret == EFI_SECURITY_VIOLATION) {
+				/*
+				 * TCG2 Protocol is installed but no TPM device found,
+				 * this is not expected.
+				 */
+				return EFI_EXIT(EFI_SECURITY_VIOLATION);
 			}
 		}
 	}
diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c
index eb95580538..773bd0677c 100644
--- a/lib/efi_loader/efi_image_loader.c
+++ b/lib/efi_loader/efi_image_loader.c
@@ -934,9 +934,16 @@ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
 
 #if CONFIG_IS_ENABLED(EFI_TCG2_PROTOCOL)
 	/* Measure an PE/COFF image */
-	if (tcg2_measure_pe_image(efi, efi_size, handle,
-				  loaded_image_info))
-		log_err("PE image measurement failed\n");
+	ret = tcg2_measure_pe_image(efi, efi_size, handle, loaded_image_info);
+	if (ret == EFI_SECURITY_VIOLATION) {
+		/*
+		 * TCG2 Protocol is installed but no TPM device found,
+		 * this is not expected.
+		 */
+		log_err("PE image measurement failed, no tpm device found\n");
+		goto err;
+	}
+
 #endif
 
 	/* Copy PE headers */
diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c
index 59bce85028..0ae07ef083 100644
--- a/lib/efi_loader/efi_tcg2.c
+++ b/lib/efi_loader/efi_tcg2.c
@@ -977,7 +977,7 @@ efi_status_t tcg2_measure_pe_image(void *efi, u64 efi_size,
 
 	ret = platform_get_tpm2_device(&dev);
 	if (ret != EFI_SUCCESS)
-		return ret;
+		return EFI_SECURITY_VIOLATION;
 
 	switch (handle->image_type) {
 	case IMAGE_SUBSYSTEM_EFI_APPLICATION:
@@ -2200,7 +2200,7 @@ efi_status_t efi_tcg2_measure_efi_app_invocation(struct efi_loaded_image_obj *ha
 
 	ret = platform_get_tpm2_device(&dev);
 	if (ret != EFI_SUCCESS)
-		return ret;
+		return EFI_SECURITY_VIOLATION;
 
 	ret = tcg2_measure_boot_variable(dev);
 	if (ret != EFI_SUCCESS)
-- 
2.17.1