### ### Untrusted apps. ### ### This file defines the rules for untrusted apps. ### Apps are labeled based on mac_permissions.xml (maps signer and ### optionally package name to seinfo value) and seapp_contexts (maps UID ### and optionally seinfo value to domain for process and type for data ### directory). The untrusted_app domain is the default assignment in ### seapp_contexts for any app with UID between APP_AID (10000) ### and AID_ISOLATED_START (99000) if the app has no specific seinfo ### value as determined from mac_permissions.xml. In current AOSP, this ### domain is assigned to all non-system apps as well as to any system apps ### that are not signed by the platform key. To move ### a system app into a specific domain, add a signer entry for it to ### mac_permissions.xml and assign it one of the pre-existing seinfo values ### or define and use a new seinfo value in both mac_permissions.xml and ### seapp_contexts. ### ### untrusted_app includes all the appdomain rules, plus the ### additional following rules: ### type untrusted_app, domain; app_domain(untrusted_app) net_domain(untrusted_app) bluetooth_domain(untrusted_app) # Some apps ship with shared libraries and binaries that they write out # to their sandbox directory and then execute. allow untrusted_app app_data_file:file { rx_file_perms execmod }; allow untrusted_app tun_device:chr_file rw_file_perms; # ASEC allow untrusted_app asec_apk_file:file r_file_perms; # Execute libs in asec containers. allow untrusted_app asec_public_file:file { execute execmod }; # Allow the allocation and use of ptys # Used by: https://play.google.com/store/apps/details?id=jackpal.androidterm create_pty(untrusted_app) # Used by Finsky / Android "Verify Apps" functionality when # running "adb install foo.apk". # TODO: Long term, we don't want apps probing into shell data files. # Figure out a way to remove these rules. allow untrusted_app shell_data_file:file r_file_perms; allow untrusted_app shell_data_file:dir r_dir_perms; # b/18504118: Allow reads from /data/anr/traces.txt # TODO: We shouldn't be allowing all untrusted_apps to read # this file. This is only needed for the GMS feedback agent. # See also b/18340553. GMS runs as untrusted_app, and # it's too late to change the domain it runs in. # This line needs to be deleted. allow untrusted_app anr_data_file:file r_file_perms; # Read and write system app data files passed over Binder. # Motivating case was /data/data/com.android.settings/cache/*.jpg for # cropping or taking user photos. allow untrusted_app system_app_data_file:file { read write getattr }; # # Rules migrated from old app domains coalesced into untrusted_app. # This includes what used to be media_app, shared_app, and release_app. # # Access /dev/mtp_usb. allow untrusted_app mtp_device:chr_file rw_file_perms; # Access to /data/media. allow untrusted_app media_rw_data_file:dir create_dir_perms; allow untrusted_app media_rw_data_file:file create_file_perms; # Write to /cache. allow untrusted_app cache_file:dir create_dir_perms; allow untrusted_app cache_file:file create_file_perms; allow untrusted_app drmserver_service:service_manager find; allow untrusted_app mediaserver_service:service_manager find; allow untrusted_app nfc_service:service_manager find; allow untrusted_app radio_service:service_manager find; allow untrusted_app surfaceflinger_service:service_manager find; allow untrusted_app system_server_service:service_manager find; allow untrusted_app tmp_system_server_service:service_manager find; service_manager_local_audit_domain(untrusted_app) auditallow untrusted_app { tmp_system_server_service -accessibility_service -account_service -activity_service -appops_service -appwidget_service -assetatlas_service -audio_service -backup_service -battery_service -batterystats_service -bluetooth_manager_service -clipboard_service -connectivity_service -content_service -country_detector_service -default_android_service -device_policy_service -diskstats_service -display_service -dropbox_service -graphicsstats_service -healthd_service -imms_service -input_method_service -input_service -jobscheduler_service -launcherapps_service -location_service -lock_settings_service -media_router_service -media_session_service -meminfo_service -mount_service -netpolicy_service -netstats_service -network_management_service -network_score_service -notification_service -persistent_data_block_service -power_service -procstats_service -registry_service -rttmanager_service -search_service -sensorservice_service -statusbar_service -textservices_service -trust_service -uimode_service -usagestats_service -user_service -vibrator_service -voiceinteraction_service -wallpaper_service -webviewupdate_service -wifi_service -wifip2p_service }:service_manager find; # Allow verifier to access staged apks. allow untrusted_app { apk_tmp_file apk_private_tmp_file }:dir r_dir_perms; allow untrusted_app { apk_tmp_file apk_private_tmp_file }:file r_file_perms; ### ### neverallow rules ### # Receive or send uevent messages. neverallow untrusted_app domain:netlink_kobject_uevent_socket *; # Receive or send generic netlink messages neverallow untrusted_app domain:netlink_socket *; # Too much leaky information in debugfs. It's a security # best practice to ensure these files aren't readable. neverallow untrusted_app debugfs:file read; # Do not allow untrusted apps to register services. # Only trusted components of Android should be registering # services. neverallow untrusted_app service_manager_type:service_manager add; # Do not allow untrusted_apps to connect to the property service # or set properties. b/10243159 neverallow untrusted_app property_socket:sock_file write; neverallow untrusted_app init:unix_stream_socket connectto; neverallow untrusted_app property_type:property_service set; # Do not allow untrusted_app to be assigned mlstrustedsubject. # This would undermine the per-user isolation model being # enforced via levelFrom=user in seapp_contexts and the mls # constraints. As there is no direct way to specify a neverallow # on attribute assignment, this relies on the fact that fork # permission only makes sense within a domain (hence should # never be granted to any other domain within mlstrustedsubject) # and untrusted_app is allowed fork permission to itself. neverallow untrusted_app mlstrustedsubject:process fork; # Do not allow untrusted_app to hard link to any files. # In particular, if untrusted_app links to other app data # files, installd will not be able to guarantee the deletion # of the linked to file. Hard links also contribute to security # bugs, so we want to ensure untrusted_app never has this # capability. neverallow untrusted_app file_type:file link;