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###
### neverallow rules for untrusted app domains
###
# Receive or send uevent messages.
neverallow { untrusted_app ephemeral_app isolated_app } domain:netlink_kobject_uevent_socket *;
# Receive or send generic netlink messages
neverallow { untrusted_app ephemeral_app isolated_app } domain:netlink_socket *;
# Too much leaky information in debugfs. It's a security
# best practice to ensure these files aren't readable.
neverallow { untrusted_app ephemeral_app isolated_app } debugfs_type:file read;
# Do not allow untrusted apps to register services.
# Only trusted components of Android should be registering
# services.
neverallow { untrusted_app ephemeral_app isolated_app } service_manager_type:service_manager add;
# Do not allow untrusted apps to connect to the property service
# or set properties. b/10243159
neverallow { untrusted_app ephemeral_app isolated_app } property_socket:sock_file write;
neverallow { untrusted_app ephemeral_app isolated_app } init:unix_stream_socket connectto;
neverallow { untrusted_app ephemeral_app isolated_app } property_type:property_service set;
# 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 { untrusted_app ephemeral_app isolated_app } 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 { untrusted_app ephemeral_app isolated_app } file_type:file link;
# Do not allow untrusted apps to access network MAC address file
neverallow { untrusted_app ephemeral_app isolated_app } sysfs_mac_address: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 { untrusted_app ephemeral_app isolated_app } domain:{ rawip_socket tcp_socket udp_socket } ioctl priv_sock_ioctls;
neverallow { untrusted_app ephemeral_app isolated_app } *:{ netlink_route_socket netlink_selinux_socket } ioctl;
neverallow { untrusted_app ephemeral_app isolated_app } *:{
socket netlink_socket packet_socket key_socket appletalk_socket
netlink_firewall_socket netlink_tcpdiag_socket netlink_nflog_socket
netlink_xfrm_socket netlink_audit_socket netlink_ip6fw_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
} *;
# Do not allow untrusted apps access to /cache
neverallow { untrusted_app ephemeral_app isolated_app } { cache_file cache_recovery_file }:dir ~{ r_dir_perms };
neverallow { untrusted_app ephemeral_app isolated_app } { 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 { untrusted_app ephemeral_app isolated_app } {
fs_type
-fuse # sdcard
-sdcardfs # sdcard
-vfat
file_type
-app_data_file # The apps sandbox itself
-media_rw_data_file # Internal storage. Known that apps can
# leave artfacts here after uninstall.
-user_profile_data_file # Access to profile files
-user_profile_foreign_dex_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 };
# Do not allow untrusted apps to directly open tun_device
neverallow { untrusted_app ephemeral_app isolated_app } tun_device:chr_file open;
# Only allow appending to /data/anr/traces.txt (b/27853304, b/18340553)
neverallow { untrusted_app ephemeral_app isolated_app } anr_data_file:file ~{ open append };
neverallow { untrusted_app ephemeral_app isolated_app } anr_data_file:dir ~search;
# Avoid reads from generically labeled /proc files
# Create a more specific label if needed
neverallow { untrusted_app ephemeral_app isolated_app } proc:file { no_rw_file_perms no_x_file_perms };