libmalcontent: Add a SessionLimits interface for time-limited sessions

This is another extension interface on accountsservice which stores
information about time and usage limits on the user session. Currently,
only a ‘daily schedule’ limit (or no limit) is supported, but additional
types and combinations of limits can be supported in future.

The daily schedule limit allows using the computer between a certain
start time and end time each day (the same each day). The user will be
kicked out of their session when the end time is reached, if they
haven’t already logged out.

This includes the getters for the new data, polkit rules for accessing
it, and some documentation. Changes to `malcontent-client` to support
session limits, setters, and unit tests will all follow.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

accounts-service/com.endlessm.ParentalControls.SessionLimits.xml

@@ -0,0 +1,50 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN"
+ "http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
+<node>
+  <interface name="com.endlessm.ParentalControls.SessionLimits">
+
+    <annotation name="org.freedesktop.Accounts.VendorExtension" value="true"/>
+
+    <annotation name="org.freedesktop.Accounts.Authentication.ChangeOwn"
+      value="com.endlessm.ParentalControls.SessionLimits.ChangeOwn"/>
+    <annotation name="org.freedesktop.Accounts.Authentication.ReadOwn"
+      value="com.endlessm.ParentalControls.SessionLimits.ReadOwn"/>
+    <annotation name="org.freedesktop.Accounts.Authentication.ChangeAny"
+      value="com.endlessm.ParentalControls.SessionLimits.ChangeAny"/>
+    <annotation name="org.freedesktop.Accounts.Authentication.ReadAny"
+      value="com.endlessm.ParentalControls.SessionLimits.ReadAny"/>
+
+    <!--
+      LimitType:
+
+      The type of session limit applied to the user, as an enumerated type.
+      Currently, the following values are supported, but more values may be
+      added in future.
+       - `0`: No filter enabled. The user is not limited in the times or
+         durations of their sessions.
+       - `1`: Daily schedule. The user is limited to using the computer between
+         a fixed start and end time each day, as set in the `DailySchedule`
+         property.
+    -->
+    <property name="LimitType" type="u" access="readwrite">
+      <annotation name="org.freedesktop.Accounts.DefaultValue" value="0"/>
+    </property>
+
+    <!--
+      DailySchedule:
+
+      A daily schedule to limit the user’s computer use. This is a two-tuple of
+      a start time and an end time, both given as the number of seconds since
+      midnight. The end time must be greater than the start time, and must be
+      ≤ 86400 (the number of seconds in a day). There is no handling of leap
+      seconds.
+
+      This property will be used if `LimitType` is set to `1`, but it must be
+      set to a valid value regardless.
+    -->
+    <property name="DailySchedule" type="(uu)" access="readwrite">
+      <annotation name="org.freedesktop.Accounts.DefaultValue" value="(0, 86400)"/>
+    </property>
+  </interface>
+</node>

accounts-service/com.endlessm.ParentalControls.policy.in

@@ -39,4 +39,44 @@
       <allow_active>auth_admin_keep</allow_active>
     </defaults>
   </action>
-</policyconfig>
+
+  <action id="com.endlessm.ParentalControls.SessionLimits.ChangeOwn">
+    <description>Change your own session limits</description>
+    <message>Authentication is required to change your session limits.</message>
+    <defaults>
+      <allow_any>auth_admin_keep</allow_any>
+      <allow_inactive>auth_admin_keep</allow_inactive>
+      <allow_active>auth_admin_keep</allow_active>
+    </defaults>
+  </action>
+
+  <action id="com.endlessm.ParentalControls.SessionLimits.ReadOwn">
+    <description>Read your own session limits</description>
+    <message>Authentication is required to read your session limits.</message>
+    <defaults>
+      <allow_any>yes</allow_any>
+      <allow_inactive>yes</allow_inactive>
+      <allow_active>yes</allow_active>
+    </defaults>
+  </action>
+
+  <action id="com.endlessm.ParentalControls.SessionLimits.ChangeAny">
+    <description>Change another user’s session limits</description>
+    <message>Authentication is required to change another user’s session limits.</message>
+    <defaults>
+      <allow_any>auth_admin_keep</allow_any>
+      <allow_inactive>auth_admin_keep</allow_inactive>
+      <allow_active>auth_admin_keep</allow_active>
+    </defaults>
+  </action>
+
+  <action id="com.endlessm.ParentalControls.SessionLimits.ReadAny">
+    <description>Read another user’s session limits</description>
+    <message>Authentication is required to read another user’s session limits.</message>
+    <defaults>
+      <allow_any>auth_admin_keep</allow_any>
+      <allow_inactive>auth_admin_keep</allow_inactive>
+      <allow_active>auth_admin_keep</allow_active>
+    </defaults>
+  </action>
+</policyconfig>

accounts-service/com.endlessm.ParentalControls.rules

@@ -23,7 +23,9 @@ polkit.addRule(function(action, subject) {
     /* Allow administrators to read parental controls (for any account) without
      * needing an additional polkit authorisation dialogue. */
     if ((action.id == "com.endlessm.ParentalControls.AppFilter.ReadOwn" ||
-         action.id == "com.endlessm.ParentalControls.AppFilter.ReadAny") &&
+         action.id == "com.endlessm.ParentalControls.AppFilter.ReadAny" ||
+         action.id == "com.endlessm.ParentalControls.SessionLimits.ReadOwn" ||
+         action.id == "com.endlessm.ParentalControls.SessionLimits.ReadAny") &&
         subject.active && subject.local &&
         subject.isInGroup("sudo")) {
             return polkit.Result.YES;

accounts-service/meson.build

@@ -6,11 +6,19 @@ i18n.merge_file('com.endlessm.ParentalControls.policy',
   install_dir: polkitpolicydir,
 )
 
-install_data('com.endlessm.ParentalControls.AppFilter.xml',
-  install_dir: dbusinterfacesdir)
-meson.add_install_script(meson_make_symlink,
-  join_paths(dbusinterfacesdir, 'com.endlessm.ParentalControls.AppFilter.xml'),
-  join_paths(accountsserviceinterfacesdir, 'com.endlessm.ParentalControls.AppFilter.xml'))
+dbus_interfaces = [
+  'com.endlessm.ParentalControls.AppFilter',
+  'com.endlessm.ParentalControls.SessionLimits',
+]
+
+foreach dbus_interface: dbus_interfaces
+  filename = dbus_interface + '.xml'
+  install_data(filename,
+    install_dir: dbusinterfacesdir)
+  meson.add_install_script(meson_make_symlink,
+    join_paths(dbusinterfacesdir, filename),
+    join_paths(accountsserviceinterfacesdir, filename))
+endforeach
 
 install_data('com.endlessm.ParentalControls.rules',
   install_dir: join_paths(get_option('datadir'), 'polkit-1', 'rules.d'))