Allow appdomain sepolicy search access to /mnt/media_rw
untrusted apps were already granted this policy and we now extend it
to all apps. This allows FileManager apps with the
MANAGE_EXTERNAL_STORAGE permisssion to access USB OTG volumes mounted
on /mnt/media_rw/<vol>.
This permission access in the framework is implemented by granting
those apps the external_storage gid. And at the same time USB volumes
will be mounted on /mnt/media_rw/<vol> with the external_storage gid.
There is no concern of interferring with FUSE on USB volumes because
they are not FUSE mounted.
For sdcards (non-USB) volumes mounted on /mnt/media_rw/<vol>, those
volumes are mounted with the media_rw gid, so even though they are
FUSE mounted on /storage/<vol>, arbitrary apps cannot access the
/mnt/media_rw path since only the FUSE daemon is granted the media_rw
gid.
Test: Manual
Bug: 182732333
Change-Id: I70a3eb1f60f32d051f44253b0db2c7b852d79ba1
diff --git a/private/app.te b/private/app.te
index 0c81515..126f11f 100644
--- a/private/app.te
+++ b/private/app.te
@@ -34,6 +34,9 @@
# Apps should not be reading vendor-defined properties.
dontaudit appdomain vendor_default_prop:file read;
+# Access to /mnt/media_rw/<vol> (limited by DAC to apps with external_storage gid)
+allow appdomain mnt_media_rw_file:dir search;
+
neverallow appdomain system_server:udp_socket {
accept append bind create ioctl listen lock name_bind
relabelfrom relabelto setattr shutdown };
diff --git a/private/system_app.te b/private/system_app.te
index 58322b8..48d5f9d 100644
--- a/private/system_app.te
+++ b/private/system_app.te
@@ -21,9 +21,6 @@
allow system_app misc_user_data_file:dir create_dir_perms;
allow system_app misc_user_data_file:file create_file_perms;
-# Access to vold-mounted storage for measuring free space
-allow system_app mnt_media_rw_file:dir search;
-
# Access to apex files stored on /data (b/136063500)
# Needed so that Settings can access NOTICE files inside apex
# files located in the assets/ directory.
diff --git a/private/untrusted_app_all.te b/private/untrusted_app_all.te
index d57939b..6064c14 100644
--- a/private/untrusted_app_all.te
+++ b/private/untrusted_app_all.te
@@ -84,10 +84,6 @@
allow untrusted_app_all media_rw_data_file:dir create_dir_perms;
allow untrusted_app_all media_rw_data_file:file create_file_perms;
-# Traverse into /mnt/media_rw for bypassing FUSE daemon
-# TODO: narrow this to just MediaProvider
-allow untrusted_app_all mnt_media_rw_file:dir search;
-
# allow cts to query all services
allow untrusted_app_all servicemanager:service_manager list;