A long time ago I published a basic example showing the skeleton of how an upload script for CKEditor should look like. Since the release of the imagepaste plugin I've received some requests to fill and explain all the details, and some people buy that plugin even before testing the free version and then they find that they don't know how to upload files.
So now I'm publishing that script with the missing part, a simple call to
move_uploaded_file($_FILES["upload"]["tmp_name"], $basePath . $name);
I've adjusted it a little so that the path to the upload folder and matching URL can be configured more easily, but it's still a very basic script. It doesn't perform any check on the uploaded files, you must take care of integrating it with your CMS (after all, that's something impossible for me to know how you're doing that part) and verify that the upload folder has the right permissions.
You can use it with CKEditor to enable the Upload tab in the Image and Link dialogs, and that way the user will be able to upload files (but not browse the existing ones). If you add the free version of the image paste plugin, then the user will be able to paste images from their clipboard into CKEditor, and the content will not be that huge mess of base64 encoded data, but a simple URL to your server with all the performance benefits that it means.
At this point, you can opt to buy the full version of the image paste plugin if you want to provide even more options for the users:
- Drag and drop from the computer for every modern browser
- Pasting images from the clipboard in Chrome (besides the basic pasting available in the free version for Firefox)
- Copy and paste a file from your computer in Firefox
- Two buttons to quickly upload a file or image for every browser. There's no way to make uploads simpler than this, other plugins still require the user to open a dialog, click browse, upload, etc... that's a huge mess and a big waste of time. Here you click and the file picker launches automatically, select the file that you want and then it's uploaded and inserted in a single step.
Back to this upload script:
I've published it at GitHub so if other people wants to provide some suggestions for better compatibility or they take the time to improve it I will try to keep it updated, but I don't really want to spend too much time on it because if by a miracle it would be a success (in fact, I wouldn't like to see too many people using this because it's really basic) then attackers would love to exploit all the weakness that it has. Please, read the documentation, all the comments and try your best to secure it as much as you can. If you download it from GitHub, you can remove those extra .git* files that it has added automatically as well as the readme and the docs when you have read them.
You only need the upload.php file and to improve a little the security by obscurity you can opt to rename it anyway that you want, just put that same name and path in the configuration of your CKEditor.
The best option would be for you to take this script as a full example and then add your customizations, your own security options, make it unique so that a simple bot can't find and use it.
This is the link to download the current version from GitHub.