/usr/src/linux-source-4.13.0.tar.bz2 is in linux-source-4.13.0 4.13.0-25.29~16.04.2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/src/linux-source-4.13.0/linux-source-4.13.0.tar.bz2
/usr/src/linux-source-4.13.0/linux-source-4.13.0.tar.bz2