StorageFilePermission

Sets the permissions set on files created in the storage directory.

StorageFilePermission= permission_setting

Note that:

It is important that the webserver has sufficient permissions to both write and remove directories.
Settting the permissions to 0666 (read and write to all) is a potential security risk.

The preferred setting is 0660 (full read and write to user and group). This requires apache to have the correct user/group access.