### ### 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; # Traverse into /mnt/media_rw for bypassing FUSE daemon # TODO: narrow this to just MediaProvider allow untrusted_app mnt_media_rw_file:dir search; # 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 app_api_service:service_manager find; # TODO: remove this once priv-apps are no longer running in untrusted_app allow untrusted_app system_api_service:service_manager find; # TODO: remove and replace with specific package that accesses this allow untrusted_app persistent_data_block_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; # limit untrusted_apps access to MAC address ioctl # MAC address is SIOCGIFHWADDR 0x8927 # from include/uapi/linux/sockios.h # #define SIOCGIFHWADDR 0x8927 /* Get hardware address */ # Other general 0x89** ioctls should continue to be allowed. # 0x8B00 from wireless extensions driver and is used by chrome to # determine if wifi is present # from include/uapi/linux/wireless.h: # #define SIOCSIWCOMMIT 0x8B00 /* Commit pending changes to driver */ allow untrusted_app self:{ rawip_socket tcp_socket udp_socket } { 0x5411 0x5451 0x8900-0x8926 0x8928-0x89ff 0x8b00-0x8bff }; auditallow untrusted_app self:{ rawip_socket tcp_socket udp_socket } { 0x8b00-0x8bff }; # 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; ') # Programs routinely attempt to scan through /system, looking # for files. Suppress the denials when they occur. dontaudit untrusted_app exec_type:file getattr; ### ### 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;