polkitd

polkitd, short for PolicyKit daemon, is the central daemon of the PolicyKit (polkit) framework on Linux systems. It runs as a background system service and provides a D-Bus API that allows applications to request elevated privileges in a controlled, policy-driven manner. The daemon’s primary role is to decide whether a given action requested by a user or process should be allowed, denied, or require authentication via an agent.

polkitd enforces policies by receiving authorization requests over D-Bus (interface org.freedesktop.PolicyKit1). It analyzes the requesting user identity, the action being requested, and the current authentication context, and then returns an authorization decision. Policy data is defined as XML action descriptions in /usr/share/polkit-1/actions, while rules and local configuration are provided in /etc/polkit-1/rules.d and /etc/polkit-1/localauthority.conf.d. For actions that require user credentials, polkitd delegates prompts to an authentication agent (for example, a graphical Polkit authentication prompt) rather than prompting directly.

polkitd is used by many desktop environments and system services to implement privilege elevation in a consistent manner, without requiring full root login. It is typically launched by the init system (for example, systemd) as polkit.service and runs on the system bus; some components may interact with the session bus as needed. Administrators can adjust policy files to fine-tune which users or groups may perform specific actions.