Hello!
I also wanted to accomplish this. I have found several ways. I am away from my current server ATM, so I cannot reference my current deployment, but in the past a secure way to add extensions was to navigate to the /plugins/cloud and modify the setup_utilities.php. At the very bottom of the file there is an array containing supported extensions. As long as the file extension you add to the array is formatted the same as all the existing types, and as long as the extension you’re adding is a valid MIME file-type WP_Cloud should transfer the file no problem. I have another method (Which I will upload later, when I can access my deployment) that will automatically allow all extensions except PHP files, which will cause problems when the server tries to transfer the file to the users Cloud folder.
Please note, the default Apache deployment will limit the max file transfer size for a client using the cloud to 2MB. If you’re hosting yourself you need to modify your PHP configuration ( /apache2/php.ini ) to allow file transfers over 2MB. It would also be a good idea to increase all the connection timeouts to a value that won’t interfere with users uploading from slow connections.
In addition to these changes, it would be a good idea to deploy some type of virus scanning. Users will be able to upload whatever they want. You don’t want to be a haven for nefarious deeds online. A strong privacy policy, some backup system using Unison, and some ClamAV anti-virus would be a good companion for your Cloud server deployment.
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