efi_loader: Fix EFI_VARIABLE_APPEND_WRITE hash check

According to UEFI v2.10 spec section 8.2.6, if a caller invokes the
SetVariables() service, it will produce a digest from hash(VariableName,
VendorGuid, Attributes, TimeStamp, DataNew_variable_content), then the
firmware that implements the SetVariable() service will compare the
digest with the result of applying the signer’s public key to the
signature. For EFI variable append write, efitools sign-efi-sig-list has
an option "-a" to add EFI_VARIABLE_APPEND_WRITE attr, and u-boot will
drop this attribute in efi_set_variable_int(). So if a caller uses
"sign-efi-sig-list -a" to create the authenticated variable, this append
write will fail in the u-boot due to "hash check failed".

This patch resumes writing the EFI_VARIABLE_APPEND_WRITE attr to ensure
that the hash check is correct. And also update the "test_efi_secboot"
test case to compliance with the change.

Signed-off-by: Weizhao Ouyang <o451686892@gmail.com>

test/py/tests/test_efi_secboot/test_authvar.py

@@ -183,7 +183,7 @@ class TestEfiAuthVar(object):
             assert 'db:' in ''.join(output)
 
             output = u_boot_console.run_command_list([
-                'fatload host 0:1 4000000 db1.auth',
+                'fatload host 0:1 4000000 db2.auth',
                 'setenv -e -nv -bs -rt -a -i 4000000:$filesize db'])
             assert 'Failed to set EFI variable' in ''.join(output)
 
@@ -197,7 +197,7 @@ class TestEfiAuthVar(object):
         with u_boot_console.log.section('Test Case 3c'):
             # Test Case 3c, update with correct signature
             output = u_boot_console.run_command_list([
-                'fatload host 0:1 4000000 db1.auth',
+                'fatload host 0:1 4000000 db2.auth',
                 'setenv -e -nv -bs -rt -at -a -i 4000000:$filesize db',
                 'printenv -e -n -guid d719b2cb-3d3a-4596-a3bc-dad00e67656f db'])
             assert 'Failed to set EFI variable' not in ''.join(output)