blob: 23e1fd2b49c25c8cb60081f0e252810789e88885 [file] [log] [blame]
###
### neverallow rules for untrusted app domains
###
define(`all_untrusted_apps',`{
ephemeral_app
isolated_app
mediaprovider
untrusted_app
untrusted_app_25
untrusted_app_27
untrusted_app_all
}')
# Receive or send uevent messages.
neverallow all_untrusted_apps domain:netlink_kobject_uevent_socket *;
# Receive or send generic netlink messages
neverallow all_untrusted_apps domain:netlink_socket *;
# Too much leaky information in debugfs. It's a security
# best practice to ensure these files aren't readable.
neverallow all_untrusted_apps { debugfs_type -debugfs_kcov }:file read;
neverallow {all_untrusted_apps userdebug_or_eng(`-domain')} debugfs_type:{ file lnk_file } read;
# Do not allow untrusted apps to register services.
# Only trusted components of Android should be registering
# services.
neverallow all_untrusted_apps service_manager_type:service_manager add;
# Do not allow untrusted apps to use VendorBinder
neverallow all_untrusted_apps vndbinder_device:chr_file *;
neverallow all_untrusted_apps vndservice_manager_type:service_manager *;
# Do not allow untrusted apps to connect to the property service
# or set properties. b/10243159
neverallow { all_untrusted_apps -mediaprovider } property_socket:sock_file write;
neverallow { all_untrusted_apps -mediaprovider } init:unix_stream_socket connectto;
neverallow { all_untrusted_apps -mediaprovider } property_type:property_service set;
# net.dns properties are not a public API. Temporarily exempt pre-Oreo apps,
# but otherwise disallow untrusted apps from reading this property.
neverallow { all_untrusted_apps -untrusted_app_25 } net_dns_prop:file read;
# Shared libraries created by trusted components within an app home
# directory can be dlopen()ed. To maintain the W^X property, these files
# must never be writable to the app.
neverallow all_untrusted_apps app_exec_data_file:file
{ append create link relabelfrom relabelto rename setattr write };
# Block calling execve() on files in an apps home directory.
# This is a W^X violation (loading executable code from a writable
# home directory). For compatibility, allow for targetApi <= 28.
# b/112357170
neverallow {
all_untrusted_apps
-untrusted_app_25
-untrusted_app_27
-runas_app
} { app_data_file privapp_data_file }:file execute_no_trans;
# Do not allow untrusted apps to invoke dex2oat. This was historically required
# by ART for compiling secondary dex files but has been removed in Q.
# Exempt legacy apps (targetApi<=28) for compatibility.
neverallow {
all_untrusted_apps
-untrusted_app_25
-untrusted_app_27
} dex2oat_exec:file no_x_file_perms;
# Do not allow untrusted apps 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 an untrusted app is allowed fork permission to itself.
neverallow all_untrusted_apps mlstrustedsubject:process fork;
# Do not allow untrusted apps to hard link to any files.
# In particular, if an 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 apps never have this
# capability.
neverallow all_untrusted_apps file_type:file link;
# Do not allow untrusted apps to access network MAC address file
neverallow all_untrusted_apps sysfs_mac_address:file no_rw_file_perms;
# Do not allow any write access to files in /sys
neverallow all_untrusted_apps sysfs_type:file { no_w_file_perms no_x_file_perms };
# Apps may never access the default sysfs label.
neverallow all_untrusted_apps sysfs:file no_rw_file_perms;
# Restrict socket ioctls. Either 1. disallow privileged ioctls, 2. disallow the
# ioctl permission, or 3. disallow the socket class.
neverallowxperm all_untrusted_apps domain:{ icmp_socket rawip_socket tcp_socket udp_socket } ioctl priv_sock_ioctls;
neverallow all_untrusted_apps *:{ netlink_route_socket netlink_selinux_socket } ioctl;
neverallow all_untrusted_apps *:{
socket netlink_socket packet_socket key_socket appletalk_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
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
} *;
# Do not allow untrusted apps access to /cache
neverallow { all_untrusted_apps -mediaprovider } { cache_file cache_recovery_file }:dir ~{ r_dir_perms };
neverallow { all_untrusted_apps -mediaprovider } { cache_file cache_recovery_file }:file ~{ read getattr };
# Do not allow untrusted apps to create/unlink files outside of its sandbox,
# internal storage or sdcard.
# World accessible data locations allow application to fill the device
# with unaccounted for data. This data will not get removed during
# application un-installation.
neverallow { all_untrusted_apps -mediaprovider } {
fs_type
-sdcard_type
file_type
-app_data_file # The apps sandbox itself
-privapp_data_file
-app_exec_data_file # stored within the app sandbox directory
-media_rw_data_file # Internal storage. Known that apps can
# leave artfacts here after uninstall.
-user_profile_data_file # Access to profile files
userdebug_or_eng(`
-method_trace_data_file # only on ro.debuggable=1
-coredump_file # userdebug/eng only
')
}:dir_file_class_set { create unlink };
# No untrusted component should be touching /dev/fuse
neverallow all_untrusted_apps fuse_device:chr_file *;
# Do not allow untrusted apps to directly open the tun_device
neverallow all_untrusted_apps tun_device:chr_file open;
# The tun_device ioctls below are not allowed, to prove equivalence
# to the kernel patch at
# https://android.googlesource.com/kernel/common/+/11cee2be0c2062ba88f04eb51196506f870a3b5d%5E%21
neverallowxperm all_untrusted_apps tun_device:chr_file ioctl {
SIOCGIFHWADDR
SIOCSIFHWADDR
TUNATTACHFILTER
TUNDETACHFILTER
TUNGETFEATURES
TUNGETFILTER
TUNGETSNDBUF
TUNGETVNETHDRSZ
TUNSETDEBUG
TUNSETGROUP
TUNSETIFF
TUNSETLINK
TUNSETNOCSUM
TUNSETOFFLOAD
TUNSETOWNER
TUNSETPERSIST
TUNSETQUEUE
TUNSETSNDBUF
TUNSETTXFILTER
TUNSETVNETHDRSZ
};
# Only allow appending to /data/anr/traces.txt (b/27853304, b/18340553)
neverallow all_untrusted_apps anr_data_file:file ~{ open append };
neverallow all_untrusted_apps anr_data_file:dir ~search;
# Avoid reads from generically labeled /proc files
# Create a more specific label if needed
neverallow all_untrusted_apps {
proc
proc_asound
proc_filesystems
proc_kmsg
proc_loadavg
proc_mounts
proc_pagetypeinfo
proc_slabinfo
proc_stat
proc_swaps
proc_uptime
proc_version
proc_vmallocinfo
proc_vmstat
}:file { no_rw_file_perms no_x_file_perms };
# Avoid all access to kernel configuration
neverallow all_untrusted_apps config_gz:file { no_rw_file_perms no_x_file_perms };
# Do not allow untrusted apps access to preloads data files
neverallow all_untrusted_apps preloads_data_file:file no_rw_file_perms;
# Locking of files on /system could lead to denial of service attacks
# against privileged system components
neverallow all_untrusted_apps system_file:file lock;
# Do not permit untrusted apps to perform actions on HwBinder service_manager
# other than find actions for services listed below
neverallow all_untrusted_apps *:hwservice_manager ~find;
# Do not permit access from apps which host arbitrary code to HwBinder services,
# except those considered sufficiently safe for access from such apps.
# The two main reasons for this are:
# 1. HwBinder servers do not perform client authentication because HIDL
# currently does not expose caller UID information and, even if it did, many
# HwBinder services either operate at a level below that of apps (e.g., HALs)
# or must not rely on app identity for authorization. Thus, to be safe, the
# default assumption is that every HwBinder service treats all its clients as
# equally authorized to perform operations offered by the service.
# 2. HAL servers (a subset of HwBinder services) contain code with higher
# incidence rate of security issues than system/core components and have
# access to lower layes of the stack (all the way down to hardware) thus
# increasing opportunities for bypassing the Android security model.
#
# Safe services include:
# - same process services: because they by definition run in the process
# of the client and thus have the same access as the client domain in which
# the process runs
# - coredomain_hwservice: are considered safe because they do not pose risks
# associated with reason #2 above.
# - hal_configstore_ISurfaceFlingerConfigs: becuase it has specifically been
# designed for use by any domain.
# - hal_graphics_allocator_hwservice: because these operations are also offered
# by surfaceflinger Binder service, which apps are permitted to access
# - hal_omx_hwservice: because this is a HwBinder version of the mediacodec
# Binder service which apps were permitted to access.
# - hal_codec2_hwservice: because this is a newer version of hal_omx_hwservice.
neverallow all_untrusted_apps {
hwservice_manager_type
-same_process_hwservice
-coredomain_hwservice
-hal_codec2_hwservice
-hal_configstore_ISurfaceFlingerConfigs
-hal_graphics_allocator_hwservice
-hal_omx_hwservice
-hal_cas_hwservice
-hal_neuralnetworks_hwservice
-untrusted_app_visible_hwservice_violators
}:hwservice_manager find;
# Make sure that the following services are never accessible by untrusted_apps
neverallow all_untrusted_apps {
default_android_hwservice
hal_atrace_hwservice
hal_audio_hwservice
hal_authsecret_hwservice
hal_bluetooth_hwservice
hal_bootctl_hwservice
hal_camera_hwservice
hal_confirmationui_hwservice
hal_contexthub_hwservice
hal_drm_hwservice
hal_dumpstate_hwservice
hal_fingerprint_hwservice
hal_gatekeeper_hwservice
hal_gnss_hwservice
hal_graphics_composer_hwservice
hal_health_hwservice
hal_input_classifier_hwservice
hal_ir_hwservice
hal_keymaster_hwservice
hal_light_hwservice
hal_memtrack_hwservice
hal_nfc_hwservice
hal_oemlock_hwservice
hal_power_hwservice
hal_power_stats_hwservice
hal_secure_element_hwservice
hal_sensors_hwservice
hal_telephony_hwservice
hal_thermal_hwservice
hal_tv_cec_hwservice
hal_tv_input_hwservice
hal_usb_hwservice
hal_vibrator_hwservice
hal_vr_hwservice
hal_weaver_hwservice
hal_wifi_hwservice
hal_wifi_offload_hwservice
hal_wifi_supplicant_hwservice
hidl_base_hwservice
system_net_netd_hwservice
thermalcallback_hwservice
}:hwservice_manager find;
# HwBinder services offered by core components (as opposed to vendor components)
# are considered somewhat safer due to point #2 above.
neverallow all_untrusted_apps {
coredomain_hwservice
-same_process_hwservice
-fwk_bufferhub_hwservice # Designed for use by any domain
-hidl_allocator_hwservice # Designed for use by any domain
-hidl_manager_hwservice # Designed for use by any domain
-hidl_memory_hwservice # Designed for use by any domain
-hidl_token_hwservice # Designed for use by any domain
}:hwservice_manager find;
# SELinux is not an API for untrusted apps to use
neverallow all_untrusted_apps selinuxfs:file no_rw_file_perms;
# Restrict *Binder access from apps to HAL domains. We can only do this on full
# Treble devices where *Binder communications between apps and HALs are tightly
# restricted.
full_treble_only(`
neverallow all_untrusted_apps {
halserverdomain
-coredomain
-hal_cas_server
-hal_codec2_server
-hal_configstore_server
-hal_graphics_allocator_server
-hal_neuralnetworks_server
-hal_omx_server
-binder_in_vendor_violators # TODO(b/35870313): Remove once all violations are gone
-untrusted_app_visible_halserver_violators
}:binder { call transfer };
')
# Access to /proc/tty/drivers, to allow apps to determine if they
# are running in an emulated environment.
# b/33214085 b/33814662 b/33791054 b/33211769
# https://github.com/strazzere/anti-emulator/blob/master/AntiEmulator/src/diff/strazzere/anti/emulator/FindEmulator.java
# This will go away in a future Android release
neverallow { all_untrusted_apps -untrusted_app_25 } proc_tty_drivers:file r_file_perms;
neverallow all_untrusted_apps proc_tty_drivers:file ~r_file_perms;
# Untrusted apps are not allowed to use cgroups.
neverallow all_untrusted_apps cgroup:file *;
# Untrusted apps targetting >= Q are not allowed to open /dev/ashmem directly.
# They must use ASharedMemory NDK API instead.
neverallow {
all_untrusted_apps
-ephemeral_app
-untrusted_app_25
-untrusted_app_27
} ashmem_device:chr_file open;