SystemD

afm-system-daemon is used to:

  • Manage users and user sessions.
  • Setup applications and services (CGroups, namespaces, autostart, permissions).
  • Use of libsystemd for its programs (event management, D-Bus interface).
Domain Object Recommendations
Platform-SystemD-1 Security model Use Namespaces for containerization.
Platform-SystemD-2 Security model Use CGroups to organise processes.

See systemd integration and user management for more information.

Benefits

  • Removal of one privileged process: afm-user-daemon
  • Access and use of high level features:

    • Socket activation.
    • Management of users and integration of PAM.
    • Dependency resolution to services.
    • Cgroups and resource control.
    • Namespaces containerization.
    • Autostart of required API.
    • Permissions and security settings.
    • Network management.

CGroups

Control Groups offer a lot of features, with the most useful ones you can control: Memory usage, how much CPU time is allocated, how much device I/O is allowed or which devices can be accessed. SystemD uses CGroups to organise processes (each service is a CGroups, and all processes started by that service use that CGroups). By default, SystemD automatically creates a hierarchy of slice, scope and service units to provide a unified structure for the CGroups tree. With the systemctl command, you can further modify this structure by creating custom slices. Currently, in AGL, there are 2 slices (user.slice and system.slice).

Namespaces

User side

There are several ways of authenticating users (Key Radio Frequency, Phone, Gesture, …). Each authentication provides dynamic allocation of uids to authenticated users. Uids is used to ensure privacy of users and SMACK for applications privacy.

First, the user initiates authentication with PAM activation. PAM Standard offers highly configurable authentication with modular design like face recognition, Voice identification or with a password. Then users should access identity services with services and applications.