6e893ec1fe
/data/local/tmp is an attacker controlled location which system_apps
should not be depending on. system_apps should only depend on files in
their home directory and files passed to them by file descriptor. To
support this best practice, neverallow access to /data/local/tmp. This
adds a compile time assertion and CTS test to assert that this rule is
never present.
This is conceptually a tightening of already defined neverallow rules in
domain.te. The existing neverallow assertions exclude appdomain, which
is too broad:
neverallow {
domain
-adbd
-appdomain
-dumpstate
-init
-installd
-simpleperf_app_runner
-system_server # why?
userdebug_or_eng(`-uncrypt')
} shell_data_file:dir { open search };
# Same as above for /data/local/tmp files. We allow shell files
# to be passed around by file descriptor, but not directly opened.
neverallow {
domain
-adbd
-appdomain
-dumpstate
-installd
userdebug_or_eng(`-uncrypt')
} shell_data_file:file open;
Test: compiles
Change-Id: Ib7178e2b9d5a41c03837a535f7db5eaf10319aac
158 lines
4.6 KiB
Text
158 lines
4.6 KiB
Text
###
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### Apps that run with the system UID, e.g. com.android.system.ui,
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### com.android.settings. These are not as privileged as the system
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### server.
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###
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typeattribute system_app coredomain;
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app_domain(system_app)
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net_domain(system_app)
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binder_service(system_app)
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# android.ui and system.ui
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allow system_app rootfs:dir getattr;
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# Read and write /data/data subdirectory.
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allow system_app system_app_data_file:dir create_dir_perms;
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allow system_app system_app_data_file:{ file lnk_file } create_file_perms;
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# Read and write to /data/misc/user.
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allow system_app misc_user_data_file:dir create_dir_perms;
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allow system_app misc_user_data_file:file create_file_perms;
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# Access to vold-mounted storage for measuring free space
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allow system_app mnt_media_rw_file:dir search;
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# Access to apex files stored on /data (b/136063500)
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# Needed so that Settings can access NOTICE files inside apex
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# files located in the assets/ directory.
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allow system_app apex_data_file:dir search;
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allow system_app staging_data_file:file r_file_perms;
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# Read wallpaper file.
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allow system_app wallpaper_file:file r_file_perms;
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# Read icon file.
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allow system_app icon_file:file r_file_perms;
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# Write to properties
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set_prop(system_app, bluetooth_a2dp_offload_prop)
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set_prop(system_app, bluetooth_audio_hal_prop)
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set_prop(system_app, bluetooth_prop)
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set_prop(system_app, debug_prop)
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set_prop(system_app, system_prop)
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set_prop(system_app, exported_bluetooth_prop)
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set_prop(system_app, exported_system_prop)
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set_prop(system_app, exported2_system_prop)
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set_prop(system_app, exported3_system_prop)
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set_prop(system_app, logd_prop)
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set_prop(system_app, net_radio_prop)
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set_prop(system_app, system_radio_prop)
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set_prop(system_app, exported_system_radio_prop)
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set_prop(system_app, log_tag_prop)
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userdebug_or_eng(`set_prop(system_app, logpersistd_logging_prop)')
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auditallow system_app net_radio_prop:property_service set;
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auditallow system_app system_radio_prop:property_service set;
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auditallow system_app exported_system_radio_prop:property_service set;
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# Allow Settings to enable Dynamic System Update
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set_prop(system_app, dynamic_system_prop)
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# ctl interface
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set_prop(system_app, ctl_default_prop)
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set_prop(system_app, ctl_bugreport_prop)
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# Create /data/anr/traces.txt.
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allow system_app anr_data_file:dir ra_dir_perms;
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allow system_app anr_data_file:file create_file_perms;
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# Settings need to access app name and icon from asec
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allow system_app asec_apk_file:file r_file_perms;
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# Allow system apps (like Settings) to interact with statsd
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binder_call(system_app, statsd)
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# Allow system apps to interact with incidentd
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binder_call(system_app, incidentd)
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# Allow system apps to interact with gpuservice
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binder_call(system_app, gpuservice)
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allow system_app servicemanager:service_manager list;
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# TODO: scope this down? Too broad?
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allow system_app {
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service_manager_type
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-apex_service
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-dnsresolver_service
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-dumpstate_service
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-installd_service
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-iorapd_service
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-lpdump_service
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-netd_service
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-system_suspend_control_service
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-virtual_touchpad_service
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-vold_service
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-vr_hwc_service
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}:service_manager find;
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# suppress denials for services system_app should not be accessing.
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dontaudit system_app {
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dnsresolver_service
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dumpstate_service
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installd_service
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iorapd_service
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netd_service
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virtual_touchpad_service
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vold_service
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vr_hwc_service
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}:service_manager find;
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allow system_app keystore:keystore_key {
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get_state
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get
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insert
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delete
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exist
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list
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reset
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password
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lock
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unlock
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is_empty
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sign
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verify
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grant
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duplicate
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clear_uid
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user_changed
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};
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# settings app reads /proc/version
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allow system_app {
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proc_version
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}:file r_file_perms;
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# Settings app writes to /dev/stune/foreground/tasks.
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allow system_app cgroup:file w_file_perms;
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control_logd(system_app)
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read_runtime_log_tags(system_app)
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get_prop(system_app, device_logging_prop)
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# allow system apps to use UDP sockets provided by the system server but not
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# modify them other than to connect
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allow system_app system_server:udp_socket {
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connect getattr read recvfrom sendto write getopt setopt };
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###
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### Neverallow rules
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###
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# app domains which access /dev/fuse should not run as system_app
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neverallow system_app fuse_device:chr_file *;
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# Apps which run as UID=system should not rely on any attacker controlled
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# filesystem locations, such as /data/local/tmp. For /data/local/tmp, we
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# allow writes to files passed by file descriptor to support dumpstate and
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# bug reports, but not reads.
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neverallow system_app shell_data_file:dir { no_w_dir_perms open search read };
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neverallow system_app shell_data_file:file { open read ioctl lock };
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