Nolan Chou

Sometimes we forgot change our file to a available name. So the plugin can help you auto change your upload file. 
I will add a filetype option of setting in next version. 
And a rename popup before the file upload if you change setting in future, default value is post_name.

wp_upload_rename

Change upload filename to random characters / random numbers / date / other by yourself.

Sajjad Hossain

This plugin allows you to restrict your site users from uploading files of certain types and control the maximum file upload size. Administrator can select the file types and file upload limit by user role. This plugin restricts users from uploading unwanted files using the WordPress media uploader.
It is very simple to use. You will be able give permissions role wise. To restore WordPress’s default selection, just deactivate the plugin.
Any issue? Please let me know (http://sajjadhossain.com/contact-me/).

WP Upload Restriction

This plugin allows you to control upload of files based on file types and sizes.

wp_upload_rename vs WP Upload Restriction