Merge "app.te: prevent locks of files on /system" am: cc45b87c am: 6fcbd0f5

am: acc1701f

Change-Id: I7b732b74d4495c9b6aede9530e7944b5b3e07584

private/app.te

@@ -87,11 +87,12 @@ allow appdomain oemfs:file rx_file_perms;
 
 # Execute the shell or other system executables.
 allow { appdomain -ephemeral_app -untrusted_v2_app } shell_exec:file rx_file_perms;
-allow { appdomain -ephemeral_app -untrusted_v2_app } system_file:file rx_file_perms;
+allow { appdomain -ephemeral_app -untrusted_v2_app } system_file:file x_file_perms;
 allow { appdomain -ephemeral_app -untrusted_v2_app } toolbox_exec:file rx_file_perms;
 
 # Renderscript needs the ability to read directories on /system
-r_dir_file(appdomain, system_file)
+allow appdomain system_file:dir r_dir_perms;
+allow appdomain system_file:lnk_file { getattr open read };
 
 # Execute dex2oat when apps call dexclassloader
 allow appdomain dex2oat_exec:file rx_file_perms;

private/app_neverallows.te

@@ -100,3 +100,7 @@ neverallow all_untrusted_apps proc:file { no_rw_file_perms no_x_file_perms };
 
 # Do not allow untrusted apps access to preloads data files
 neverallow all_untrusted_apps preloads_data_file:file no_rw_file_perms;
+
+# Locking of files on /system could lead to denial of service attacks
+# against privileged system components
+neverallow all_untrusted_apps system_file:file lock;