efi_loader: implement UninstallProtocolInterface

Without the patch efi_uninstall_protocol_interface always returns an
error.

With the patch protocols without interface can be uninstalled.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>

lib/efi_loader/efi_boottime.c

@@ -371,8 +371,44 @@ static efi_status_t EFIAPI efi_reinstall_protocol_interface(void *handle,
 static efi_status_t EFIAPI efi_uninstall_protocol_interface(void *handle,
 			efi_guid_t *protocol, void *protocol_interface)
 {
+	struct list_head *lhandle;
+	int i;
+	efi_status_t r = EFI_NOT_FOUND;
+
 	EFI_ENTRY("%p, %p, %p", handle, protocol, protocol_interface);
-	return EFI_EXIT(EFI_NOT_FOUND);
+
+	if (!handle || !protocol) {
+		r = EFI_INVALID_PARAMETER;
+		goto out;
+	}
+
+	list_for_each(lhandle, &efi_obj_list) {
+		struct efi_object *efiobj;
+		efiobj = list_entry(lhandle, struct efi_object, link);
+
+		if (efiobj->handle != handle)
+			continue;
+
+		for (i = 0; i < ARRAY_SIZE(efiobj->protocols); i++) {
+			struct efi_handler *handler = &efiobj->protocols[i];
+			const efi_guid_t *hprotocol = handler->guid;
+
+			if (!hprotocol)
+				continue;
+			if (!guidcmp(hprotocol, protocol)) {
+				if (handler->protocol_interface) {
+					r = EFI_ACCESS_DENIED;
+				} else {
+					handler->guid = 0;
+					r = EFI_SUCCESS;
+				}
+				goto out;
+			}
+		}
+	}
+
+out:
+	return EFI_EXIT(r);
 }
 
 static efi_status_t EFIAPI efi_register_protocol_notify(efi_guid_t *protocol,
@@ -813,7 +849,7 @@ static efi_status_t EFIAPI efi_open_protocol(
 			struct efi_handler *handler = &efiobj->protocols[i];
 			const efi_guid_t *hprotocol = handler->guid;
 			if (!hprotocol)
-				break;
+				continue;
 			if (!guidcmp(hprotocol, protocol)) {
 				if (attributes !=
 				    EFI_OPEN_PROTOCOL_TEST_PROTOCOL) {