Suppress "Failed to open <..>\revocations.efi" when file does not exist

Attempting to call loadimage on revocations.efi when it isn't present
should results in error messages being printed to the console on at
least some firmware:

	Failed to open \EFI\distro\revocations.efi - Not Found
	Failed to load image ...: Not Found

Of course this is going to be the normal case on nearly all systems, at
least to begin with. Since we are about to loop through the directory
entries anyway, we can just make two passes, first looking for
revocations.efi and then looking for shim_certificate.efi. This will
still ensure that any revocations in revocations.efi are picked up
before shim_certificate.efi is loaded without resulting in any noise on
the console.

Signed-off-by: Jan Setje-Eilers <Jan.SetjeEilers@oracle.com>

1 files changed, 40 insertions, 10 deletions

diff --git a/shim.c b/shim.c
index a0379721..d800f675 100644
--- a/shim.c
+++ b/shim.c
@@ -1549,6 +1549,7 @@ load_unbundled_trust(EFI_HANDLE image_handle)
 	EFI_FILE_IO_INTERFACE *drive;
 	UINTN buffersize = 0;
 	void *buffer = NULL;
+	BOOLEAN search_revocations = TRUE;
 
 	efi_status = gBS->HandleProtocol(image_handle, &EFI_LOADED_IMAGE_GUID,
 					 (void **)&li);
@@ -1584,13 +1585,6 @@ load_unbundled_trust(EFI_HANDLE image_handle)
 	if (!secure_mode())
 		goto done;
 
-	/*
-	 * In the event that there are unprocessed revocation additions, they
-	 * could be intended to ban any *new* trust anchors we find here.
-	 * With that in mind, we always want to do a pass of loading
-	 * revocations before we try to add anything new to our allowlist.
-	 */
-	load_revocations_file(image_handle, PathName);
 
 	while (true) {
 		UINTN old = buffersize;
@@ -1625,10 +1619,46 @@ load_unbundled_trust(EFI_HANDLE image_handle)
 		}
 
 		info = (EFI_FILE_INFO *)buffer;
-		if (buffersize == 0 || !info)
-			goto done;
+		if (buffersize == 0 || !info) {
+			if (search_revocations) {
+				search_revocations = FALSE;
+				efi_status = root->Open(root, &dir, PathName,
+							EFI_FILE_MODE_READ, 0);
+				if (EFI_ERROR(efi_status)) {
+					perror(L"Failed to open %s - %r\n",
+					       PathName, efi_status);
+					goto done;
+				}
+				continue;
+			} else {
+				goto done;
+			}
+		}
+
+		/*
+		 * In the event that there are unprocessed revocation
+		 * additions, they could be intended to ban any *new* trust
+		 * anchors we find here. With that in mind, we always want to
+		 * do a pass of loading revocations before we try to add
+		 * anything new to our allowlist. This is done by making two
+		 * passes over the directory, first to search for the
+		 * revocations.efi file then to search for shim_certificate.efi
+		 */
+		if (search_revocations &&
+		    StrCaseCmp(info->FileName, L"revocations.efi") == 0) {
+			load_revocations_file(image_handle, PathName);
+			search_revocations = FALSE;
+			efi_status = root->Open(root, &dir, PathName,
+						EFI_FILE_MODE_READ, 0);
+			if (EFI_ERROR(efi_status)) {
+				perror(L"Failed to open %s - %r\n",
+				       PathName, efi_status);
+				goto done;
+			}
+		}
 
-		if (StrCaseCmp(info->FileName, L"shim_certificate.efi") == 0) {
+		if (!search_revocations &&
+		    StrCaseCmp(info->FileName, L"shim_certificate.efi") == 0) {
 			load_cert_file(image_handle, info->FileName, PathName);
 		}
 	}