platform_system_sepolicy/private/app_zygote.te

typeattribute app_zygote coredomain;

######
###### Policy below is different from regular zygote-spawned apps
######

# The app_zygote needs to be able to transition domains.
typeattribute app_zygote mlstrustedsubject;

# Allow access to temporary files, which is normally permitted through
# a domain macro.
tmpfs_domain(app_zygote);

# Set the UID/GID of the process.
# This will be further limited to a range of isolated UIDs with seccomp.
allow app_zygote self:global_capability_class_set { setgid setuid };
# Drop capabilities from bounding set.
allow app_zygote self:global_capability_class_set setpcap;
# Switch SELinux context to isolated app domain.
allow app_zygote self:process setcurrent;
allow app_zygote isolated_app:process dyntransition;

# For JIT
allow app_zygote self:process execmem;

# Allow app_zygote to stat the files that it opens. It must
# be able to inspect them so that it can reopen them on fork
# if necessary: b/30963384.
allow app_zygote debugfs_trace_marker:file getattr;

# get system_server process group
allow app_zygote system_server:process getpgid;

# Interaction between the app_zygote and its children.
allow app_zygote isolated_app:process setpgid;

# TODO (b/63631799) fix this access
dontaudit app_zygote mnt_expand_file:dir getattr;

# Get seapp_contexts
allow app_zygote seapp_contexts_file:file r_file_perms;
# Check validity of SELinux context before use.
selinux_check_context(app_zygote)
# Check SELinux permissions.
selinux_check_access(app_zygote)

######
###### Policy below is shared with regular zygote-spawned apps
######

# Child of zygote.
allow app_zygote zygote:fd use;
allow app_zygote zygote:process sigchld;

# For ART (read /data/dalvik-cache).
r_dir_file(app_zygote, dalvikcache_data_file);
allow app_zygote dalvikcache_data_file:file execute;

# Allow reading/executing installed binaries to enable preloading
# application data
allow app_zygote apk_data_file:dir r_dir_perms;
allow app_zygote apk_data_file:file { r_file_perms execute };

# /oem accesses.
allow app_zygote oemfs:dir search;

# Allow app_zygote access to /vendor/overlay
r_dir_file(app_zygote, vendor_overlay_file)

allow app_zygote system_data_file:lnk_file r_file_perms;
allow app_zygote system_data_file:file { getattr read map };

# Send unsolicited message to system_server
unix_socket_send(app_zygote, system_unsolzygote, system_server)

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

# Only permit transition to isolated_app.
neverallow app_zygote { domain -isolated_app }:process dyntransition;

# Only setcon() transitions, no exec() based transitions, except for crash_dump.
neverallow app_zygote { domain -crash_dump }:process transition;

# Must not exec() a program without changing domains.
# Having said that, exec() above is not allowed.
neverallow app_zygote *:file execute_no_trans;

# The only way to enter this domain is for the zygote to fork a new
# app_zygote child.
neverallow { domain -zygote } app_zygote:process dyntransition;

# Disallow write access to properties.
neverallow app_zygote property_socket:sock_file write;
neverallow app_zygote property_type:property_service set;

# Should not have any access to non-app data files.
neverallow app_zygote {
    bluetooth_data_file
    nfc_data_file
    radio_data_file
    shell_data_file
}:file { rwx_file_perms };

neverallow app_zygote {
    service_manager_type
    -activity_service
    -webviewupdate_service
}:service_manager find;

# Isolated apps should not be able to access the driver directly.
neverallow app_zygote gpu_device:chr_file { rwx_file_perms };

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

# Do not allow most socket access. This is socket_class_set, excluding unix_dgram_socket,
# unix_stream_socket, and netlink_selinux_socket.
neverallow app_zygote domain:{
  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_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
} *;

# Only allow app_zygote to talk to the logd socket, and su/heapprofd on eng/userdebug
# This is because cap_setuid/cap_setgid allow to forge uid/gid in SCM_CREDENTIALS.
# Think twice before changing.
neverallow app_zygote {
  domain
  -app_zygote
  -logd
  -system_server
  userdebug_or_eng(`-su')
  userdebug_or_eng(`-heapprofd')
}:unix_dgram_socket *;

neverallow app_zygote {
  domain
  -app_zygote
  userdebug_or_eng(`-su')
  userdebug_or_eng(`-heapprofd')
}:unix_stream_socket *;

# Never allow ptrace
neverallow app_zygote *:process ptrace;

# Do not allow access to Bluetooth-related system properties.
# neverallow rules for Bluetooth-related data files are listed above.
neverallow app_zygote {
  bluetooth_a2dp_offload_prop
  bluetooth_audio_hal_prop
  bluetooth_prop
  exported_bluetooth_prop
}:file create_file_perms;