libpam-systemd 215-5ubuntu2 (amd64 binary) in ubuntu vivid

 systemd is a replacement for sysvinit. It is dependency-based and
 able to read the LSB init script headers in addition to parsing rcN.d
 links as hints.
 .
 It also provides process supervision using cgroups and the ability to
 not only depend on other init script being started, but also
 availability of a given mount point or dbus service.
 .
 This package contains the PAM module which registers user sessions in
 the systemd control group hierarchy.
 .
 If in doubt, do install this package.
 .
 Packages that depend on logind functionality need to depend on libpam-systemd.