/etc/ is in policykit-1 0.105-18+deb9u1.
This file is owned by root:root, with mode 0o755.
..
/etc/polkit-1/localauthority.conf.d/
/etc/dbus-1/
/etc/dbus-1/system.d/
/etc/dbus-1/system.d/org.freedesktop.PolicyKit1.conf
/etc/pam.d/
/etc/pam.d/polkit-1
/etc/polkit-1/
/etc/polkit-1/localauthority/
/etc/polkit-1/localauthority/10-vendor.d/
/etc/polkit-1/localauthority/20-org.d/
/etc/polkit-1/localauthority/30-site.d/
/etc/polkit-1/localauthority/50-local.d/
/etc/polkit-1/localauthority/90-mandatory.d/
/etc/polkit-1/localauthority.conf.d/50-localauthority.conf
/etc/polkit-1/localauthority.conf.d/51-debian-sudo.conf
/etc/polkit-1/nullbackend.conf.d/
/etc/polkit-1/nullbackend.conf.d/50-nullbackend.conf