At the core of every Linux system is the Linux kernel. Any malicious code that is able to damage or take control of a system also has repercussions that affect the Linux kernel. So, it only makes clear to users that having a secure kernel is also an important part of the equation. Fortunately, the Linux kernel is secure and has a number of security features and programs. The man behind all this is James Morris, the maintainer of the Linux kernel security subsystem. There is even a separate Linux repository for this that can be accessed at http://git.kernel.org/?p=linux/kernel/git/jmorris/linux-security.git;a=summary. Also, by inspecting http://kernsec.org/wiki/index.php/Main_Page, which is the main page of the Linux kernel security subsystem, you can see the exact projects that are managed inside this subsystem and maybe lend a hand to them if you're interested.
There is also a workgroup that provides security enhancements and verifications to the Linux kernel to make sure...