platform_system_sepolicy/public/app.te

###
### Domain for all zygote spawned apps
###
### This file is the base policy for all zygote spawned apps.
### Other policy files, such as isolated_app.te, untrusted_app.te, etc
### extend from this policy. Only policies which should apply to ALL
### zygote spawned apps should be added here.
###
type appdomain_tmpfs, file_type;

###
### Neverallow rules
###
### These are things that Android apps should NEVER be able to do
###

# Superuser capabilities.
# bluetooth requires net_admin and wake_alarm. network stack app requires net_admin.
neverallow { appdomain -bluetooth -network_stack } self:capability_class_set *;

# Block device access.
neverallow appdomain dev_type:blk_file { read write };

# Note: Try expanding list of app domains in the future.
neverallow { untrusted_app isolated_app shell } graphics_device:chr_file { read write };

neverallow { appdomain -nfc } nfc_device:chr_file
    { read write };
neverallow { appdomain -bluetooth } hci_attach_dev:chr_file
    { read write };
neverallow appdomain tee_device:chr_file { read write };

# Privileged netlink socket interfaces.
neverallow { appdomain -network_stack }
    domain:{
        netlink_tcpdiag_socket
        netlink_nflog_socket
        netlink_xfrm_socket
        netlink_audit_socket
        netlink_dnrt_socket
    } *;

# These messages are broadcast messages from the kernel to userspace.
# Do not allow the writing of netlink messages, which has been a source
# of rooting vulns in the past.
neverallow { appdomain -network_stack }
    domain:netlink_kobject_uevent_socket { write append };

# Sockets under /dev/socket that are not specifically typed.
neverallow appdomain socket_device:sock_file write;

# Unix domain sockets.
neverallow appdomain adbd_socket:sock_file write;
neverallow { appdomain -radio } rild_socket:sock_file write;

# ptrace access to non-app domains.
neverallow appdomain { domain -appdomain }:process ptrace;

# The Android security model guarantees the confidentiality and integrity
# of application data and execution state. Ptrace bypasses those
# confidentiality guarantees. Disallow ptrace access from system components
# to apps. Crash_dump is excluded, as it needs ptrace access to
# produce stack traces.  llkd is excluded, as it needs ptrace access to
# inspect stack traces for live lock conditions.

neverallow {
  domain
  -appdomain
  -crash_dump
  userdebug_or_eng(`-llkd')
} appdomain:process ptrace;

# Read or write access to /proc/pid entries for any non-app domain.
# A different form of hidepid=2 like protections
neverallow appdomain { domain -appdomain }:file no_w_file_perms;
neverallow { appdomain -shell } { domain -appdomain }:file no_rw_file_perms;

# signal access to non-app domains.
# sigchld allowed for parent death notification.
# signull allowed for kill(pid, 0) existence test.
# All others prohibited.
# -perfetto is to allow shell (which is an appdomain) to kill perfetto
# (see private/shell.te).
neverallow appdomain { domain -appdomain -perfetto }:process
    { sigkill sigstop signal };

# Write to rootfs.
neverallow appdomain rootfs:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };

# Write to /system.
neverallow appdomain system_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };

# Write to entrypoint executables.
neverallow appdomain exec_type:file
    { create write setattr relabelfrom relabelto append unlink link rename };

# Write to system-owned parts of /data.
# This is the default type for anything under /data not otherwise
# specified in file_contexts.  Define a different type for portions
# that should be writable by apps.
neverallow appdomain system_data_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };

# Write to various other parts of /data.
neverallow appdomain drm_data_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };
neverallow { appdomain -platform_app }
    apk_data_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };
neverallow { appdomain -platform_app }
    apk_tmp_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };
neverallow { appdomain -platform_app }
    apk_private_data_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };
neverallow { appdomain -platform_app }
    apk_private_tmp_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };
neverallow { appdomain -shell }
    shell_data_file:dir_file_class_set
    { create setattr relabelfrom relabelto append unlink link rename };
neverallow { appdomain -bluetooth }
    bluetooth_data_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };
neverallow { domain -credstore -init } credstore_data_file:dir_file_class_set *;
neverallow appdomain
    keystore_data_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };
neverallow appdomain
    systemkeys_data_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };
neverallow appdomain
    wifi_data_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };
neverallow appdomain
    dhcp_data_file:dir_file_class_set
    { create write setattr relabelfrom relabelto append unlink link rename };

# access tmp apk files
neverallow { appdomain -untrusted_app_all -platform_app -priv_app }
    { apk_tmp_file apk_private_tmp_file }:dir_file_class_set *;

neverallow untrusted_app_all { apk_tmp_file apk_private_tmp_file }:{ devfile_class_set dir fifo_file lnk_file sock_file } *;
neverallow untrusted_app_all { apk_tmp_file apk_private_tmp_file }:file ~{ getattr read };

# Access to factory files.
neverallow appdomain efs_file:dir_file_class_set write;
neverallow { appdomain -shell } efs_file:dir_file_class_set read;

# Write to various pseudo file systems.
neverallow { appdomain -bluetooth -nfc }
    sysfs:dir_file_class_set write;
neverallow appdomain
    proc:dir_file_class_set write;

# Access to syslog(2) or /proc/kmsg.
neverallow appdomain kernel:system { syslog_read syslog_mod syslog_console };

# SELinux is not an API for apps to use
neverallow { appdomain -shell } *:security { compute_av check_context };
neverallow { appdomain -shell } *:netlink_selinux_socket *;

# Ability to perform any filesystem operation other than statfs(2).
# i.e. no mount(2), unmount(2), etc.
neverallow appdomain fs_type:filesystem ~getattr;

# prevent creation/manipulation of globally readable symlinks
neverallow appdomain {
  apk_data_file
  cache_file
  cache_recovery_file
  dev_type
  rootfs
  system_file
  tmpfs
}:lnk_file no_w_file_perms;

# Applications should use the activity model for receiving events
neverallow {
  appdomain
  -shell # bugreport
} input_device:chr_file ~getattr;

# Do not allow access to Bluetooth-related system properties except for a few allowed domains.
# neverallow rules for access to Bluetooth-related data files are above.
neverallow {
  appdomain
  -bluetooth
  -system_app
} { bluetooth_audio_hal_prop bluetooth_a2dp_offload_prop bluetooth_prop exported_bluetooth_prop }:file create_file_perms;

# allow system_app to access Nfc-related system properties.
set_prop(system_app, nfc_prop)

# allow system_app to access radio_config system properties.
set_prop(system_app, radio_control_prop)

# Apps cannot access proc_uid_time_in_state
neverallow appdomain proc_uid_time_in_state:file *;

# Apps cannot access proc_uid_concurrent_active_time
neverallow appdomain proc_uid_concurrent_active_time:file *;

# Apps cannot access proc_uid_concurrent_policy_time
neverallow appdomain proc_uid_concurrent_policy_time:file *;

# Apps cannot access proc_uid_cpupower
neverallow appdomain proc_uid_cpupower:file *;

# Apps may not read /proc/net/{tcp,tcp6,udp,udp6}. These files leak information across the
# application boundary. VPN apps may use the ConnectivityManager.getConnectionOwnerUid() API to
# perform UID lookups.
neverallow { appdomain -shell } proc_net_tcp_udp:file *;

# Apps cannot access bootstrap files. The bootstrap files are only for
# extremely early processes (like init, etc.) which are started before
# the runtime APEX is activated and Bionic libs are provided from there.
# If app process accesses (or even load/execute) the bootstrap files,
# it might cause problems such as ODR violation, etc.
neverallow appdomain system_bootstrap_lib_file:file
    { open read write append execute execute_no_trans map };
neverallow appdomain system_bootstrap_lib_file:dir
    { open read getattr search };