public/mediaextractor.te

# mediaextractor - multimedia daemon
type mediaextractor, domain;
type mediaextractor_exec, exec_type, file_type;

typeattribute mediaextractor mlstrustedsubject;

binder_use(mediaextractor)
binder_call(mediaextractor, binderservicedomain)
binder_call(mediaextractor, appdomain)
binder_service(mediaextractor)

add_service(mediaextractor, mediaextractor_service)
allow mediaextractor mediametrics_service:service_manager find;
allow mediaextractor hidl_token_hwservice:hwservice_manager find;

allow mediaextractor system_server:fd use;

hal_client_domain(mediaextractor, hal_cas)

r_dir_file(mediaextractor, cgroup)
allow mediaextractor proc_meminfo:file r_file_perms;

crash_dump_fallback(mediaextractor)

# Suppress denials from sdcardfs (b/67454004)
dontaudit mediaextractor sdcardfs:file read;

# allow mediaextractor read permissions for file sources
allow mediaextractor media_rw_data_file:file { getattr read };
allow mediaextractor app_data_file:file { getattr read };

# Read resources from open apk files passed over Binder
allow mediaextractor apk_data_file:file { read getattr };
allow mediaextractor asec_apk_file:file { read getattr };
allow mediaextractor ringtone_file:file { read getattr };

# scan extractor library directory to dynamically load extractors
allow mediaextractor system_file:dir { read open };

userdebug_or_eng(`
  # Allow extractor to add update service.
  add_service(mediaextractor, mediaextractor_update_service)

  # Allow extractor to load media extractor plugins from update apk.
  allow mediaextractor apk_data_file:dir search;
  allow mediaextractor apk_data_file:file { execute open };
')

###
### neverallow rules
###

# mediaextractor should never execute any executable without a
# domain transition
neverallow mediaextractor { file_type fs_type }:file execute_no_trans;

# The goal of the mediaserver split is to place media processing code into
# restrictive sandboxes with limited responsibilities and thus limited
# permissions. Example: Audioserver is only responsible for controlling audio
# hardware and processing audio content. Cameraserver does the same for camera
# hardware/content. Etc.
#
# Media processing code is inherently risky and thus should have limited
# permissions and be isolated from the rest of the system and network.
# Lengthier explanation here:
# https://android-developers.googleblog.com/2016/05/hardening-media-stack.html
neverallow mediaextractor domain:{ tcp_socket udp_socket rawip_socket } *;

# mediaextractor should not be opening /data files directly. Any files
# it touches (with a few exceptions) need to be passed to it via a file
# descriptor opened outside the process.
neverallow mediaextractor {
  data_file_type
  -zoneinfo_data_file # time zone data from /data/misc/zoneinfo
  userdebug_or_eng(`-apk_data_file') # for loading media extractor plugins
}:file open;