Privileged permission allowlist

Privileged apps are system apps located in a priv-app directory on a system image partition. The partitions used for Android releases are:

Android 9 and higher: /system, /product, /vendor
Android 8.1 and lower: /system

Note: On this page, /etc/permissions/priv-app resolves to partition/etc/permissions/priv-app.

Historically, device manufacturers had little control over which signature | privileged permissions could be granted to privileged apps. Starting in Android 8.0, manufacturers can explicitly grant privileged permissions in the system configuration XML files in the /etc/permissions directory. As of Android 9, implementors can explicitly grant or deny all privileged permissions. If privileged permissions are not granted, the device won't boot.

The privapp-permissions.xml file can only grant or deny permissions for privileged apps on the same partition. For example, if an app on the /product partition requests privileged permissions, the request can only be granted or denied by a privapp-permissions.xml file on /product.

Note: Permissions defined by the core platform (the android package) and CarService (com.android.car.updatable) must be allowlisted. Privileged permissions defined by device manufacturers are automatically granted. Only list apps in the privapp-permissions.xml file that actually exist on the partition. When an app isn't on the partition, the entry is ignored. Privileged apps on the /vendor partition can only have privileged permissions whose protection level is set to vendorPrivileged.

Add an allowlist

Permission allowlists for apps can be listed in a single XML file or in multiple XML files located in the frameworks/base/etc/permissions directory:

/etc/permissions/privapp-permissions-OEM_NAME.xml
/etc/permissions/privapp-permissions-DEVICE_NAME.xml

No strict rule applies to how content is organized. Device implementers can determine content structure as long as all apps from /system/priv-app are allowlisted. For example, Google has developed a single allowlist for all privileged apps. We recommend the following organization:

Permissions for apps already included in the Android Open Source Project (AOSP) tree are listed in /etc/permissions/privapp-permissions-platform.xml.
For other apps, use files of the form, /etc/permissions/privapp-permissions-DEVICE_NAME.xml.

Customize an allowlist

AOSP includes an allowlist implementation that can be customized as needed.

If a permission must be denied, edit the XML to use a deny-permission tag instead of a permissiontag. For example:

<!-- This XML file declares which signature|privileged permissions to grant to
privileged apps that come with the platform -->

    <permissions>
      <privapp-permissions package="com.android.backupconfirm">
        <permission name="android.permission.BACKUP"/>
        <permission name="android.permission.CRYPT_KEEPER"/>
      </privapp-permissions>

      <privapp-permissions package="com.android.cellbroadcastreceiver">

        <!-- Don't allow the application to interact across users -->

        <deny-permission name="android.permission.INTERACT_ACROSS_USERS"/>
        <permission name="android.permission.MANAGE_USERS"/>
        <permission name="android.permission.MODIFY_PHONE_STATE"/>
        <permission name="android.permission.READ_PRIVILEGED_PHONE_STATE"/>
        <permission name="android.permission.RECEIVE_EMERGENCY_BROADCAST"/>
      </privapp-permissions>
    ...

Find missing permissions

To find missing permissions when starting a new device, enable transitional log mode:

ro.control_privapp_permissions=log

Violations are reported in the log file. Non-privileged permissions are granted. Doing so ensures the device remains in a working state while still providing the list of violations. The error message format is as follows:

PackageManager: Privileged permission {PERMISSION_NAME} for package {PACKAGE_NAME} - not in privapp-permissions allowlist

All violations must be addressed by adding the missing permissions to the appropriate allowlists. Note that in:

Android 9 and higher, violations of privileged permissions prevent the device from starting. Instead, you must explicitly allow or deny all privileged permissions.
Android 8.0 and lower, missing permissions are not granted to the affected apps despite being in the priv-app path.

Enforce an allowlist

After you create your allowlists, enable runtime enforcement by setting the build property ro.control_privapp_permissions=enforce.

Allowlisting is required only for permissions declared by apps with package="android". The ro.control_privapp_permissions property state must adhere to Section 9.1 Permissions in the Compatibility Definition Document (CDD).