/etc/pam.d/chpasswd is in passwd 1:4.1.4.2+svn3283-3ubuntu5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | # The PAM configuration file for the Shadow 'chpasswd' service
#
@include common-password
|