hw/uefi: add var-service-pkcs7-stub.c

pkcs7 stub which is used in case gnutls is not available.

It throws EFI_WRITE_PROTECTED errors unconditionally, so all
authenticated variables are readonly for the guest.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-ID: <20250225163031.1409078-13-kraxel@redhat.com>

hw/uefi/var-service-pkcs7-stub.c

@@ -0,0 +1,16 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * uefi vars device - pkcs7 stubs
+ */
+#include "qemu/osdep.h"
+#include "system/dma.h"
+
+#include "hw/uefi/var-service.h"
+
+efi_status uefi_vars_check_pkcs7_2(uefi_variable *siglist,
+                                   void **digest, uint32_t *digest_size,
+                                   mm_variable_access *va, void *data)
+{
+    return EFI_WRITE_PROTECTED;
+}