Linux as distributed by kernel.org contains non-Free Software.  The
goal of this project is to maintain and publish versions of the Linux
kernel that can meet the needs of users who seek freedom, and that can
be easily adopted by 100% Free GNU/Linux distros, as well as by their
users, by distros that want to enable their users to choose freedom,
and users of those that don't.

Please see http://fsfla.org/selibre/linux-libre for more information.