Add the ability to write shell files to the untrusted_app domain.

Bug: 10290009
Change-Id: Ic794299261672b36a2b630893b65ab176c3eee6b
(cherry picked from commit eaa4e844e4c8549c9b4808a1272876a6995ca5a7)

untrusted_app.te

@@ -44,5 +44,8 @@ allow untrusted_app devpts:chr_file rw_file_perms;
 # running "adb install foo.apk".
 # TODO: Long term, we don't want apps probing into shell data files.
 # Figure out a way to remove these rules.
-allow untrusted_app shell_data_file:file r_file_perms;
+# XXX Adding writing to shell_data_file to fix 10290009; this needs a real fix,
+# as allowing apps to write shell data files is a significant possible security
+# vuln
+allow untrusted_app shell_data_file:file rw_file_perms;
 allow untrusted_app shell_data_file:dir r_dir_perms;