blob: 12357c79d6c8c5a0959c4ef789e4068cb38fc58a [file] [log] [blame]
###
### neverallow rules for untrusted app domains
###
define(`all_untrusted_apps',`{
ephemeral_app
isolated_app
mediaprovider
mediaprovider_app
untrusted_app
untrusted_app_25
untrusted_app_27
untrusted_app_29
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. Disallow untrusted apps from reading this property.
neverallow { all_untrusted_apps } 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_net: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
} *;
# Disallow sending RTM_GETLINK messages on netlink sockets.
neverallow {
all_untrusted_apps
-untrusted_app_25
-untrusted_app_27
-untrusted_app_29
} domain:netlink_route_socket { bind nlmsg_readpriv };
# 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 except mediaprovider_app should be touching /dev/fuse
neverallow { all_untrusted_apps -mediaprovider_app } 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 ~{ FIOCLEX FIONCLEX TUNGETIFF };
# 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_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 };
# /proc/filesystems is accessible to mediaprovider_app only since it handles
# external storage
neverallow { all_untrusted_apps - mediaprovider_app } proc_filesystems: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 the protected HwBinder
# services.
# The two main reasons for this are:
# 1. Protected HwBinder servers do not perform client authentication because HIDL
# currently does not expose caller UID information and, even if it did, those
# 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.
neverallow all_untrusted_apps protected_hwservice:hwservice_manager find;
neverallow all_untrusted_apps {
vendor_service
}:service_manager find;
# SELinux is not an API for untrusted apps to use
neverallow all_untrusted_apps selinuxfs:file no_rw_file_perms;
# 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 *;
# /mnt/sdcard symlink was supposed to have been removed in Gingerbread. Apps
# must not use it.
neverallow {
all_untrusted_apps
-untrusted_app_25
-untrusted_app_27
} mnt_sdcard_file:lnk_file *;
# Only privileged apps may find the incident service
neverallow all_untrusted_apps incident_service:service_manager find;