My old and somewhat related PoC project for screen casts, but still working. Just checked (debian wheezy with stock kernel 3.2.0-4-amd64). It requires building and loading simple kernel module, though.
Apparently nowadays debugfs is owner-only rw, so you have to change it or start it as root.
Look for the top-right corner to see the effect while you're typing or clicking something.
P.S. Funny thing is that I don't know why I wrote >>Kprobe dependency can be easily removed by writing own input handler and it will be done in future<< back then, because when I evaluated this statement year or so ago, it didn't look that easy, and there would be more code in the end, I suppose.
Apparently nowadays debugfs is owner-only rw, so you have to change it or start it as root.
https://github.com/przemoc/kaos
Look for the top-right corner to see the effect while you're typing or clicking something.
P.S. Funny thing is that I don't know why I wrote >>Kprobe dependency can be easily removed by writing own input handler and it will be done in future<< back then, because when I evaluated this statement year or so ago, it didn't look that easy, and there would be more code in the end, I suppose.