platform_system_sepolicy/private/ephemeral_app.te
Thiébaud Weksteen 9ec532752d Add fusefs_type for FUSE filesystems
Any FUSE filesystem will receive the 'fuse' type when mounted. It is
possible to change this behaviour by specifying the "context=" or
"fscontext=" option in mount().

Because 'fuse' has historically been used only for the emulated storage,
it also received the 'sdcard_type' attribute. Replace the 'sdcard_type'
attribute from 'fuse' with the new 'fusefs_type'. This attribute can be
attached on derived types (such as app_fusefs).

This change:
- Remove the neverallow restriction on this new type. This means any
  custom FUSE implementation can be mounted/unmounted (if the correct
  allow rule is added). See domain.te.
- Change the attribute of 'fuse' from 'sdcard_type' to 'fusefs_type'.
  See file.te.
- Modify all references to 'sdcard_type' to explicitly include 'fuse'
  for compatibility reason.

Bug: 177481425
Bug: 190804537
Test: Build and boot aosp_cf_x86_64_phone-userdebug
Change-Id: Id4e410a049f72647accd4c3cf43eaa55e94c318f
2021-06-28 13:18:46 +02:00

95 lines
3.7 KiB
Text

###
### Ephemeral apps.
###
### This file defines the security policy for apps with the ephemeral
### feature.
###
### The ephemeral_app domain is a reduced permissions sandbox allowing
### ephemeral applications to be safely installed and run. Non ephemeral
### applications may also opt-in to ephemeral to take advantage of the
### additional security features.
###
### PackageManager flags an app as ephemeral at install time.
typeattribute ephemeral_app coredomain;
net_domain(ephemeral_app)
app_domain(ephemeral_app)
# Allow ephemeral apps to read/write files in visible storage if provided fds
allow ephemeral_app { sdcard_type fuse media_rw_data_file }:file {read write getattr ioctl lock append};
# Some apps ship with shared libraries and binaries that they write out
# to their sandbox directory and then execute.
allow ephemeral_app privapp_data_file:file { r_file_perms execute };
allow ephemeral_app app_data_file:file { r_file_perms execute };
# Follow priv-app symlinks. This is used for dynamite functionality.
allow ephemeral_app privapp_data_file:lnk_file r_file_perms;
# Allow the renderscript compiler to be run.
domain_auto_trans(ephemeral_app, rs_exec, rs)
# Allow loading and deleting shared libraries created by trusted system
# components within an application home directory.
allow ephemeral_app app_exec_data_file:file { r_file_perms execute unlink };
# services
allow ephemeral_app audioserver_service:service_manager find;
allow ephemeral_app cameraserver_service:service_manager find;
allow ephemeral_app mediaserver_service:service_manager find;
allow ephemeral_app mediaextractor_service:service_manager find;
allow ephemeral_app mediametrics_service:service_manager find;
allow ephemeral_app mediadrmserver_service:service_manager find;
allow ephemeral_app drmserver_service:service_manager find;
allow ephemeral_app radio_service:service_manager find;
allow ephemeral_app ephemeral_app_api_service:service_manager find;
# Write app-specific trace data to the Perfetto traced damon. This requires
# connecting to its producer socket and obtaining a (per-process) tmpfs fd.
perfetto_producer(ephemeral_app)
# Allow profiling if the app opts in by being marked profileable/debuggable.
can_profile_heap(ephemeral_app)
can_profile_perf(ephemeral_app)
# allow ephemeral apps to use UDP sockets provided by the system server but not
# modify them other than to connect
allow ephemeral_app system_server:udp_socket {
connect getattr read recvfrom sendto write getopt setopt };
allow ephemeral_app ashmem_device:chr_file rw_file_perms;
###
### neverallow rules
###
neverallow ephemeral_app { app_data_file privapp_data_file }:file execute_no_trans;
# Receive or send uevent messages.
neverallow ephemeral_app domain:netlink_kobject_uevent_socket *;
# Receive or send generic netlink messages
neverallow ephemeral_app domain:netlink_socket *;
# Too much leaky information in debugfs. It's a security
# best practice to ensure these files aren't readable.
neverallow ephemeral_app debugfs:file read;
# execute gpu_device
neverallow ephemeral_app gpu_device:chr_file execute;
# access files in /sys with the default sysfs label
neverallow ephemeral_app sysfs:file *;
# Avoid reads from generically labeled /proc files
# Create a more specific label if needed
neverallow ephemeral_app proc:file { no_rw_file_perms no_x_file_perms };
# Directly access external storage
neverallow ephemeral_app { sdcard_type fuse media_rw_data_file }:file {open create};
neverallow ephemeral_app { sdcard_type fuse media_rw_data_file }:dir search;
# Avoid reads to proc_net, it contains too much device wide information about
# ongoing connections.
neverallow ephemeral_app proc_net:file no_rw_file_perms;