android_system_sepolicy/private/isolated_app.te

###
### Services with isolatedProcess=true in their manifest.
###
### This file defines the rules for isolated apps. An "isolated
### app" is an APP with UID between AID_ISOLATED_START (99000)
### and AID_ISOLATED_END (99999).
###

typeattribute isolated_app coredomain;

app_domain(isolated_app)

# Access already open app data files received over Binder or local socket IPC.
allow isolated_app { app_data_file privapp_data_file }:file { append read write getattr lock map };

allow isolated_app activity_service:service_manager find;
allow isolated_app display_service:service_manager find;
allow isolated_app webviewupdate_service:service_manager find;

# Google Breakpad (crash reporter for Chrome) relies on ptrace
# functionality. Without the ability to ptrace, the crash reporter
# tool is broken.
# b/20150694
# https://code.google.com/p/chromium/issues/detail?id=475270
allow isolated_app self:process ptrace;

# b/32896414: Allow accessing sdcard file descriptors passed to isolated_apps
# by other processes. Open should never be allowed, and is blocked by
# neverallow rules below.
# media_rw_data_file is included for sdcardfs, and can be removed if sdcardfs
# is modified to change the secontext when accessing the lower filesystem.
allow isolated_app { sdcard_type media_rw_data_file }:file { read write append getattr lock map };

# For webviews, isolated_app processes can be forked from the webview_zygote
# in addition to the zygote. Allow access to resources inherited from the
# webview_zygote process. These rules are specialized copies of the ones in app.te.
# Inherit FDs from the webview_zygote.
allow isolated_app webview_zygote:fd use;
# Notify webview_zygote of child death.
allow isolated_app webview_zygote:process sigchld;
# Inherit logd write socket.
allow isolated_app webview_zygote:unix_dgram_socket write;
# Read system properties managed by webview_zygote.
allow isolated_app webview_zygote_tmpfs:file read;

# TODO (b/63631799) fix this access
# suppress denials to /data/local/tmp
dontaudit isolated_app shell_data_file:dir search;

# Write app-specific trace data to the Perfetto traced damon. This requires
# connecting to its producer socket and obtaining a (per-process) tmpfs fd.
allow isolated_app traced:fd use;
allow isolated_app traced_tmpfs:file { read write getattr map };
unix_socket_connect(isolated_app, traced_producer, traced)

#####
##### Neverallow
#####

# Isolated apps should not directly open app data files themselves.
neverallow isolated_app { app_data_file privapp_data_file }:file open;

# Only allow appending to /data/anr/traces.txt (b/27853304, b/18340553)
# TODO: are there situations where isolated_apps write to this file?
# TODO: should we tighten these restrictions further?
neverallow isolated_app anr_data_file:file ~{ open append };
neverallow isolated_app anr_data_file:dir ~search;

# Isolated apps must not be permitted to use HwBinder
neverallow isolated_app hwbinder_device:chr_file *;
neverallow isolated_app *:hwservice_manager *;

# Isolated apps must not be permitted to use VndBinder
neverallow isolated_app vndbinder_device:chr_file *;

# Isolated apps must not be permitted to perform actions on Binder and VndBinder service_manager
# except the find actions for services whitelisted below.
neverallow isolated_app *:service_manager ~find;

# b/17487348
# Isolated apps can only access three services,
# activity_service, display_service and webviewupdate_service.
neverallow isolated_app {
    service_manager_type
    -activity_service
    -display_service
    -webviewupdate_service
}:service_manager find;

# Isolated apps shouldn't be able to access the driver directly.
neverallow isolated_app gpu_device:chr_file { rw_file_perms execute };

# Do not allow isolated_app access to /cache
neverallow isolated_app cache_file:dir ~{ r_dir_perms };
neverallow isolated_app cache_file:file ~{ read getattr };

# Do not allow isolated_app to access external storage, except for files passed
# via file descriptors (b/32896414).
neverallow isolated_app { storage_file mnt_user_file sdcard_type }:dir ~getattr;
neverallow isolated_app { storage_file mnt_user_file }:file_class_set *;
neverallow isolated_app sdcard_type:{ devfile_class_set lnk_file sock_file fifo_file } *;
neverallow isolated_app sdcard_type:file ~{ read write append getattr lock map };

# Do not allow USB access
neverallow isolated_app { usb_device usbaccessory_device }:chr_file *;

# Restrict the webview_zygote control socket.
neverallow isolated_app webview_zygote:sock_file write;

# Limit the /sys files which isolated_app can access. This is important
# for controlling isolated_app attack surface.
neverallow isolated_app {
  sysfs_type
  -sysfs_devices_system_cpu
  -sysfs_usb # TODO: check with audio team if needed for isolated_app (b/28417852)
}:file no_rw_file_perms;

# No creation of sockets families other than AF_UNIX sockets.
# List taken from system/sepolicy/public/global_macros - socket_class_set
# excluding unix_stream_socket and unix_dgram_socket.
# Many of these are socket families which have never and will never
# be compiled into the Android kernel.
neverallow isolated_app self:{
  socket tcp_socket udp_socket rawip_socket netlink_socket packet_socket
  key_socket appletalk_socket netlink_route_socket
  netlink_tcpdiag_socket netlink_nflog_socket netlink_xfrm_socket
  netlink_selinux_socket netlink_audit_socket netlink_dnrt_socket
  netlink_kobject_uevent_socket tun_socket netlink_iscsi_socket
  netlink_fib_lookup_socket netlink_connector_socket netlink_netfilter_socket
  netlink_generic_socket netlink_scsitransport_socket netlink_rdma_socket
  netlink_crypto_socket sctp_socket icmp_socket ax25_socket ipx_socket
  netrom_socket atmpvc_socket x25_socket rose_socket decnet_socket atmsvc_socket
  rds_socket irda_socket pppox_socket llc_socket can_socket tipc_socket
  bluetooth_socket iucv_socket rxrpc_socket isdn_socket phonet_socket
  ieee802154_socket caif_socket alg_socket nfc_socket vsock_socket kcm_socket
  qipcrtr_socket smc_socket xdp_socket
} create;