platform_system_sepolicy/private/domain.te

# Transition to crash_dump when /system/bin/crash_dump* is executed.
# This occurs when the process crashes.
# We do not apply this to the su domain to avoid interfering with
# tests (b/114136122)
domain_auto_trans({ domain userdebug_or_eng(`-su') }, crash_dump_exec, crash_dump);
allow domain crash_dump:process sigchld;

# Allow every process to check the heapprofd.enable properties to determine
# whether to load the heap profiling library. This does not necessarily enable
# heap profiling, as initialization will fail if it does not have the
# necessary SELinux permissions.
get_prop(domain, heapprofd_prop);
# Allow heap profiling on debug builds.
userdebug_or_eng(`can_profile_heap_userdebug_or_eng({
  domain
  -bpfloader
  -init
  -kernel
  -keystore
  -llkd
  -logd
  -logpersist
  -recovery
  -recovery_persist
  -recovery_refresh
  -ueventd
  -vendor_init
  -vold
})')

# Path resolution access in cgroups.
allow domain cgroup:dir search;
allow { domain -appdomain -rs } cgroup:dir w_dir_perms;
allow { domain -appdomain -rs } cgroup:file w_file_perms;

allow domain cgroup_rc_file:dir search;
allow domain cgroup_rc_file:file r_file_perms;
allow domain task_profiles_file:file r_file_perms;
allow domain vendor_task_profiles_file:file r_file_perms;

# Allow all domains to read sys.use_memfd to determine
# if memfd support can be used if device supports it
get_prop(domain, use_memfd_prop);

# For now, everyone can access core property files
# Device specific properties are not granted by default
not_compatible_property(`
    get_prop(domain, core_property_type)
    get_prop(domain, exported_dalvik_prop)
    get_prop(domain, exported_ffs_prop)
    get_prop(domain, exported_system_radio_prop)
    get_prop(domain, exported2_config_prop)
    get_prop(domain, exported2_radio_prop)
    get_prop(domain, exported2_system_prop)
    get_prop(domain, exported2_vold_prop)
    get_prop(domain, exported3_default_prop)
    get_prop(domain, exported3_radio_prop)
    get_prop(domain, exported3_system_prop)
    get_prop(domain, vendor_default_prop)
')
compatible_property_only(`
    get_prop({coredomain appdomain shell}, core_property_type)
    get_prop({coredomain appdomain shell}, exported_dalvik_prop)
    get_prop({coredomain appdomain shell}, exported_ffs_prop)
    get_prop({coredomain appdomain shell}, exported_system_radio_prop)
    get_prop({coredomain appdomain shell}, exported2_config_prop)
    get_prop({coredomain appdomain shell}, exported2_radio_prop)
    get_prop({coredomain appdomain shell}, exported2_system_prop)
    get_prop({coredomain appdomain shell}, exported2_vold_prop)
    get_prop({coredomain appdomain shell}, exported3_default_prop)
    get_prop({coredomain appdomain shell}, exported3_radio_prop)
    get_prop({coredomain appdomain shell}, exported3_system_prop)
    get_prop({domain -coredomain -appdomain}, vendor_default_prop)
')

# Allow access to fsverity keyring.
allow domain kernel:key search;
# Allow access to keys in the fsverity keyring that were installed at boot.
allow domain fsverity_init:key search;
# For testing purposes, allow access to keys installed with su.
userdebug_or_eng(`
  allow domain su:key search;
')

# Limit ability to ptrace or read sensitive /proc/pid files of processes
# with other UIDs to these whitelisted domains.
neverallow {
  domain
  -vold
  userdebug_or_eng(`-llkd')
  -dumpstate
  userdebug_or_eng(`-incidentd')
  -storaged
  -system_server
  userdebug_or_eng(`-perfprofd')
} self:global_capability_class_set sys_ptrace;

# Limit ability to generate hardware unique device ID attestations to priv_apps
neverallow { domain -priv_app } *:keystore_key gen_unique_id;

neverallow {
  domain
  -init
  -vendor_init
  userdebug_or_eng(`-domain')
} debugfs_tracing_debug:file no_rw_file_perms;

# System_server owns dropbox data, and init creates/restorecons the directory
# Disallow direct access by other processes.
neverallow { domain -init -system_server } dropbox_data_file:dir *;
neverallow { domain -init -system_server } dropbox_data_file:file ~{ getattr read };

###
# Services should respect app sandboxes
neverallow {
  domain
  -appdomain
  -installd # creation of sandbox
} { privapp_data_file app_data_file }:dir_file_class_set { create unlink };

# Only the following processes should be directly accessing private app
# directories.
neverallow {
  domain
  -adbd
  -appdomain
  -app_zygote
  -dexoptanalyzer
  -installd
  userdebug_or_eng(`-perfprofd')
  -profman
  -rs # spawned by appdomain, so carryover the exception above
  -runas
  -system_server
  -viewcompiler
} { privapp_data_file app_data_file }:dir *;

# Only apps should be modifying app data. installd is exempted for
# restorecon and package install/uninstall.
neverallow {
  domain
  -appdomain
  -installd
  -rs # spawned by appdomain, so carryover the exception above
} { privapp_data_file app_data_file }:dir ~r_dir_perms;

neverallow {
  domain
  -appdomain
  -app_zygote
  -installd
  userdebug_or_eng(`-perfprofd')
  -rs # spawned by appdomain, so carryover the exception above
} { privapp_data_file app_data_file }:file_class_set open;

neverallow {
  domain
  -appdomain
  -installd # creation of sandbox
} { privapp_data_file app_data_file }:dir_file_class_set { create unlink };

neverallow {
  domain
  -installd
} { privapp_data_file app_data_file }:dir_file_class_set { relabelfrom relabelto };

# The staging directory contains APEX and APK files. It is important to ensure
# that these files cannot be accessed by other domains to ensure that the files
# do not change between system_server staging the files and apexd processing
# the files.
neverallow { domain -init -system_server -apexd -installd} staging_data_file:dir *;
neverallow { domain -init -system_server -apexd -kernel -installd } staging_data_file:file *;
neverallow { domain -init -system_server -installd} staging_data_file:dir no_w_dir_perms;
# apexd needs the link and unlink permissions, so list every `no_w_file_perms`
# except for `link` and `unlink`.
neverallow { domain -init -system_server } staging_data_file:file
  { append create relabelfrom rename setattr write no_x_file_perms };

neverallow {
    domain
    -appdomain # for oemfs
    -bootanim # for oemfs
    -recovery # for /tmp/update_binary in tmpfs
} { fs_type -rootfs }:file execute;

#
# Assert that, to the extent possible, we're not loading executable content from
# outside the rootfs or /system partition except for a few whitelisted domains.
# Executable files loaded from /data is a persistence vector
# we want to avoid. See
# https://bugs.chromium.org/p/project-zero/issues/detail?id=955 for example.
#
neverallow {
    domain
    -appdomain
    with_asan(`-asan_extract')
    -shell
    userdebug_or_eng(`-su')
    -system_server_startup # for memfd backed executable regions
    -app_zygote
    -webview_zygote
    -zygote
    userdebug_or_eng(`-mediaextractor')
    userdebug_or_eng(`-mediaswcodec')
} {
    file_type
    -system_file_type
    -system_lib_file
    -system_linker_exec
    -vendor_file_type
    -exec_type
    -postinstall_file
}:file execute;

# Only init is allowed to write cgroup.rc file
neverallow {
  domain
  -init
  -vendor_init
} cgroup_rc_file:file no_w_file_perms;

# Only authorized processes should be writing to files in /data/dalvik-cache
neverallow {
  domain
  -init # TODO: limit init to relabelfrom for files
  -zygote
  -installd
  -postinstall_dexopt
  -cppreopts
  -dex2oat
  -otapreopt_slot
  -art_apex_postinstall
  -art_apex_boot_integrity
} dalvikcache_data_file:file no_w_file_perms;

neverallow {
  domain
  -init
  -installd
  -postinstall_dexopt
  -cppreopts
  -dex2oat
  -zygote
  -otapreopt_slot
  -art_apex_boot_integrity
  -art_apex_postinstall
} dalvikcache_data_file:dir no_w_dir_perms;

# Minimize dac_override and dac_read_search.
# Instead of granting them it is usually better to add the domain to
# a Unix group or change the permissions of a file.
define(`dac_override_allowed', `{
  dnsmasq
  dumpstate
  init
  installd
  install_recovery
  userdebug_or_eng(`llkd')
  lmkd
  netd
  perfprofd
  postinstall_dexopt
  recovery
  rss_hwm_reset
  sdcardd
  tee
  ueventd
  uncrypt
  vendor_init
  vold
  vold_prepare_subdirs
  zygote
}')
neverallow ~dac_override_allowed self:global_capability_class_set dac_override;
# Since the kernel checks dac_read_search before dac_override, domains that
# have dac_override should also have dac_read_search to eliminate spurious
# denials.  Some domains have dac_read_search without having dac_override, so
# this list should be a superset of the one above.
neverallow ~{
  dac_override_allowed
  traced_probes
  userdebug_or_eng(`heapprofd')
} self:global_capability_class_set dac_read_search;

# Limit what domains can mount filesystems or change their mount flags.
# sdcard_type / vfat is exempt as a larger set of domains need
# this capability, including device-specific domains.
neverallow {
    domain
    -apexd
    recovery_only(`userdebug_or_eng(`-fastbootd')')
    -init
    -kernel
    -otapreopt_chroot
    -recovery
    -update_engine
    -vold
    -zygote
} { fs_type -sdcard_type }:filesystem { mount remount relabelfrom relabelto };

# Limit raw I/O to these whitelisted domains. Do not apply to debug builds.
neverallow {
  domain
  userdebug_or_eng(`-domain')
  -kernel
  -gsid
  -init
  -recovery
  -ueventd
  -healthd
  -uncrypt
  -tee
  -hal_bootctl_server
} self:global_capability_class_set sys_rawio;