# Putting rickrolling in kernel space

Kernelroll is a linux kernel module for advanced rickrolling.

It works by patching the open() system call to open a specified music file
instead of other music files. Currently, it only checks if the file extension
"mp3" is present and calls the original open() with the supplied path
instead.

WARNING: There is probably a performance penalty and your kernel might crash
at a very inappropriate time and cause data loss! You are responsible for
the code you load into your kernel!

But most probably, it will be alright! ;)

# Installation

You need the address of sys_call_table in your kernel. Use

    $ grep sys_call_table /boot/System.map-3.0.0-1-amd64
    ffffffff81400300 R sys_call_table

on the respective System.map of your kernel to find out the address

Now fire up kernelroll.c and add yours:

    void **sys_call_table = (void **)0xffffffff81400300;

This will probably be simplified in the future, but as sys_call_table isn't
exported anymore in 2.6 kernels, we have to use some tricks.

Compile with:

    $ make

Load with:

    $ insmod kernelroll.ko rollfile=/path/to/rickroll.mp3

Fire up a music player of your choice, play a song and consider yourself
kernelrolled. ;)