Protect dropbox service data with selinux

Create a new label for /data/system/dropbox, and neverallow direct
access to anything other than init and system_server.

While all apps may write to the dropbox service, only apps with
android.permission.READ_LOGS, a signature|privileged|development
permission, may read them. Grant access to priv_app, system_app,
and platform_app, and neverallow access to all untrusted_apps.

Bug: 31681871
Test: atest CtsStatsdHostTestCases
Test: atest DropBoxTest
Test: atest ErrorsTests
Change-Id: Ice302b74b13c4d66e07b069c1cdac55954d9f5df

private/app_neverallows.te

@@ -258,3 +258,8 @@ full_treble_only(`
 
 # Untrusted apps are not allowed to find mediaextractor update service.
 neverallow all_untrusted_apps mediaextractor_update_service:service_manager find;
+
+# Untrusted apps are not allowed to use the signature|privileged|development
+# android.permission.READ_LOGS permission, so they may not read dropbox files.
+# Access to the the dropbox directory is covered by a neverallow for domain.
+neverallow all_untrusted_apps dropbox_data_file:file *;

private/compat/26.0/26.0.cil

@@ -641,6 +641,7 @@
 (typeattributeset system_block_device_26_0 (system_block_device))
 (typeattributeset system_data_file_26_0
   ( system_data_file
+    dropbox_data_file
     vendor_data_file))
 (typeattributeset system_file_26_0 (system_file))
 (typeattributeset systemkeys_data_file_26_0 (systemkeys_data_file))

private/compat/27.0/27.0.cil

@@ -1359,6 +1359,7 @@
 (typeattributeset system_block_device_27_0 (system_block_device))
 (typeattributeset system_data_file_27_0
   ( system_data_file
+    dropbox_data_file
     vendor_data_file))
 (typeattributeset system_file_27_0 (system_file))
 (typeattributeset systemkeys_data_file_27_0 (systemkeys_data_file))

private/domain.te

@@ -116,3 +116,8 @@ full_treble_only(`
     -init
   }{ usbfs binfmt_miscfs }:file no_rw_file_perms;
 ')
+
+# System_server owns dropbox data, and init creates/restorecons the directory
+# Disallow direct access by other processes.
+neverallow { domain -init -system_server } dropbox_data_file:dir *;
+neverallow { domain -init -system_server } dropbox_data_file:file ~{ getattr read };

private/file_contexts

@@ -432,6 +432,7 @@
 /data/misc/perfprofd(/.*)?      u:object_r:perfprofd_data_file:s0
 /data/misc/update_engine(/.*)?  u:object_r:update_engine_data_file:s0
 /data/misc/update_engine_log(/.*)?  u:object_r:update_engine_log_data_file:s0
+/data/system/dropbox(/.*)?      u:object_r:dropbox_data_file:s0
 /data/system/heapdump(/.*)?     u:object_r:heapdump_data_file:s0
 /data/misc/trace(/.*)?          u:object_r:method_trace_data_file:s0
 /data/misc/wmtrace(/.*)?        u:object_r:wm_trace_data_file:s0

private/platform_app.te

@@ -27,6 +27,9 @@ allow platform_app asec_apk_file:file create_file_perms;
 allow platform_app media_rw_data_file:dir create_dir_perms;
 allow platform_app media_rw_data_file:file create_file_perms;
 
+# Read access to FDs from the DropboxManagerService.
+allow platform_app dropbox_data_file:file { getattr read };
+
 # Write to /cache.
 allow platform_app cache_file:dir create_dir_perms;
 allow platform_app cache_file:file create_file_perms;

private/priv_app.te

@@ -53,6 +53,9 @@ allow priv_app ota_package_file:file create_file_perms;
 allow priv_app media_rw_data_file:dir create_dir_perms;
 allow priv_app media_rw_data_file:file create_file_perms;
 
+# Read access to FDs from the DropboxManagerService.
+allow priv_app dropbox_data_file:file { getattr read };
+
 # Used by Finsky / Android "Verify Apps" functionality when
 # running "adb install foo.apk".
 allow priv_app shell_data_file:file r_file_perms;

private/system_app.te

@@ -24,6 +24,9 @@ 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;
 
+# Read access to FDs from the DropboxManagerService.
+allow system_app dropbox_data_file:file { getattr read };
+
 # Read wallpaper file.
 allow system_app wallpaper_file:file r_file_perms;
 

private/system_server.te

@@ -391,6 +391,10 @@ userdebug_or_eng(`
 allow system_server backup_data_file:dir create_dir_perms;
 allow system_server backup_data_file:file create_file_perms;
 
+# Write to /data/system/dropbox
+allow system_server dropbox_data_file:dir create_dir_perms;
+allow system_server dropbox_data_file:file create_file_perms;
+
 # Write to /data/system/heapdump
 allow system_server heapdump_data_file:dir rw_dir_perms;
 allow system_server heapdump_data_file:file create_file_perms;

public/file.te

@@ -202,6 +202,8 @@ type shell_data_file, file_type, data_file_type, core_data_file_type, mlstrusted
 type property_data_file, file_type, data_file_type, core_data_file_type;
 # /data/bootchart
 type bootchart_data_file, file_type, data_file_type, core_data_file_type;
+# /data/system/dropbox
+type dropbox_data_file, file_type, data_file_type, core_data_file_type;
 # /data/system/heapdump
 type heapdump_data_file, file_type, data_file_type, core_data_file_type, mlstrustedobject;
 # /data/nativetest

public/init.te

@@ -164,11 +164,11 @@ allow init {
 allow init {
   file_type
   -app_data_file
-  -runtime_event_log_tags_file
   -exec_type
   -keystore_data_file
   -misc_logd_file
   -nativetest_data_file
+  -runtime_event_log_tags_file
   -shell_data_file
   -system_app_data_file
   -system_file