/usr/lib/x86_64-linux-gnu/libdlm.so.3 is in libdlm3 4.0.7-1ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libdlm.so.3.0
/usr/lib/x86_64-linux-gnu/libdlm.so.3.0