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Chapter 4. Displaying the system security classification

As an administrator of deployments where the user must be aware of the security classification of the system, you can set up a notification of the security classification. This can be either a permanent banner or a temporary notification, and it can appear on login screen, in the GNOME session, and on the lock screen.

4.1. Enabling system security classification banners

You can create a permanent classification banner to state the overall security classification level of the system. This is useful for deployments where the user must always be aware of the security classification level of the system that they are logged into.

The permanent classification banner can appear within the running session, the lock screen, and login screen, and customize its background color, its font, and its position within the screen.

This procedure creates a red banner with a white text placed on both the top and bottom of the login screen.

Procedure

  1. Install the gnome-shell-extension-classification-banner package:

    # dnf install gnome-shell-extension-classification-banner
  2. Create the 99-class-banner file at either of the following locations:

    • To configure a notification at the login screen, create /etc/dconf/db/gdm.d/99-class-banner.
    • To configure a notification in the user session, create /etc/dconf/db/local.d/99-class-banner.
  3. Enter the following configuration in the created file:

    [org/gnome/shell]
    enabled-extensions=['classification-banner@gnome-shell-extensions.gcampax.github.com']
    
    [org/gnome/shell/extensions/classification-banner]
    background-color='rgba(200,16,46,0.75)'
    message='TOP SECRET'
    top-banner=true
    bottom-banner=true
    system-info=true
    color='rgb(255,255,255)'
    Warning

    This configuration overrides similar configuration files that also enable an extension, such as Notifying of the system security classification.

    To enable multiple extensions, specify all of them in the enabled-extensions list. For example:

    enabled-extensions=['heads-up-display@gnome-shell-extensions.gcampax.github.com', 'classification-banner@gnome-shell-extensions.gcampax.github.com']
  4. Update the dconf database:

    # dconf update
  5. Reboot the system.

Troubleshooting

  • If the classification banners are not displayed for an existing user, log in as the user and enable the Classification banner extension using the Extensions application.

4.2. Notifying of the system security classification

You can set up a notification that contains a predefined message in an overlay banner. This is useful for deployments where the user is required to read the security classification of the system before logging in.

Depending on your configuration, the notification can appear at the login screen, after logging in, on the lock screen, or after a longer time with no user activity. You can always dismiss the notification when it appears.

Procedure

  1. Install the gnome-shell-extension-heads-up-display package:

    # dnf install gnome-shell-extension-heads-up-display
  2. Create the 99-hud-message file at either of the following locations:

    • To configure a notification at the login screen, create /etc/dconf/db/gdm.d/99-hud-message.
    • To configure a notification in the user session, create /etc/dconf/db/local.d/99-hud-message.
  3. Enter the following configuration in the created file:

    [org/gnome/shell]
    enabled-extensions=['heads-up-display@gnome-shell-extensions.gcampax.github.com']
    
    [org/gnome/shell/extensions/heads-up-display]
    message-heading="Security classification title"
    message-body="Security classification description"
    # The following options control when the notification appears:
    show-when-locked=true
    show-when-unlocking=true
    show-when-unlocked=true

    Replace the following values with text that describes the security classification of your system:

    Security classification title
    A short heading that identifies the security classification.
    Security classification description
    A longer message that provides additional details, such as references to various guidelines.
    Warning

    This configuration overrides similar configuration files that also enable an extension, such as Enabling system security classification banners.

    To enable multiple extensions, specify all of them in the enabled-extensions list. For example:

    enabled-extensions=['heads-up-display@gnome-shell-extensions.gcampax.github.com', 'classification-banner@gnome-shell-extensions.gcampax.github.com']
  4. Update the dconf database:

    # dconf update
  5. Reboot the system.

Troubleshooting

  • If the notifications are not displayed for an existing user, log in as the user and enable the Heads-up display message extension using the Extensions application.