### ### 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 }; # 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; # 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 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; # Traverse into /mnt/media_rw for bypassing FUSE daemon # TODO: narrow this to just MediaProvider allow untrusted_app mnt_media_rw_file:dir search; # allow cts to query all services allow untrusted_app servicemanager:service_manager list; allow untrusted_app audioserver_service:service_manager find; allow untrusted_app cameraserver_service:service_manager find; allow untrusted_app drmserver_service:service_manager find; allow untrusted_app mediaserver_service:service_manager find; allow untrusted_app mediaextractor_service:service_manager find; allow untrusted_app mediacodec_service:service_manager find; allow untrusted_app mediadrmserver_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 app_api_service:service_manager find; # Allow GMS core to access perfprofd output, which is stored # in /data/misc/perfprofd/. GMS core will need to list all # data stored in that directory to process them one by one. userdebug_or_eng(` allow untrusted_app perfprofd_data_file:file r_file_perms; allow untrusted_app perfprofd_data_file:dir r_dir_perms; ') # gdbserver for ndk-gdb ptrace attaches to app process. allow untrusted_app self:process ptrace; # Programs routinely attempt to scan through /system, looking # for files. Suppress the denials when they occur. dontaudit untrusted_app exec_type:file getattr; # TODO: switch to meminfo service allow untrusted_app proc_meminfo:file r_file_perms; # access /proc/net/xt_qtguid/stats r_dir_file(untrusted_app, proc_net) # Cts: HwRngTest allow untrusted_app sysfs_hwrandom:dir search; allow untrusted_app sysfs_hwrandom: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_type: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; # Do not allow untrusted_app to access network MAC address file neverallow untrusted_app sysfs_mac_address:file no_rw_file_perms; # do not allow privileged socket ioctl commands neverallowxperm untrusted_app domain:{ rawip_socket tcp_socket udp_socket } ioctl priv_sock_ioctls; # Do not allow untrusted_app access to /cache neverallow untrusted_app { cache_file cache_recovery_file }:dir ~{ r_dir_perms }; neverallow untrusted_app { cache_file cache_recovery_file }:file ~{ read getattr }; # Do not allow untrusted_app to set system properties. neverallow untrusted_app property_socket:sock_file write; neverallow untrusted_app property_type:property_service set; # Do not allow untrusted_app to create/unlink files outside of its sandbox, # internal storage or sdcard. # World accessible data locations allow application to fill the device # with unaccounted for data. This data will not get removed during # application un-installation. neverallow untrusted_app { fs_type -fuse # sdcard file_type -app_data_file # The apps sandbox itself -media_rw_data_file # Internal storage. Known that apps can # leave artfacts here after uninstall. -user_profile_data_file # Access to profile files -user_profile_foreign_dex_data_file # Access to profile files userdebug_or_eng(` -method_trace_data_file # only on ro.debuggable=1 -coredump_file # userdebug/eng only ') }:dir_file_class_set { create unlink }; # Do not allow untrusted_app to directly open tun_device neverallow untrusted_app tun_device:chr_file open;