/lib/udev/rules.d/45-dlm.rules is in libdlm3 3.1.7-0ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | KERNEL=="dlm-control|dlm-monitor|dlm_default", MODE="0666", SYMLINK+="misc/%k"
KERNEL=="dlm_*", MODE="0660", SYMLINK+="misc/%k"
|