Allow system server and uncrypt to operate pipe file

System server and uncrypt need to communicate with a named pipe on the
/cache partition. It will be created and deleted by system server.

Bug: 20012567
Bug: 20949086
(cherry picked from commit 70c6dbf0)
Change-Id: I4ddc523c2a0f4218877dae8f8a9b7fcf3f786625

system_server.te

@@ -302,6 +302,7 @@ allow system_server system_ndebug_socket:sock_file create_file_perms;
 # Manage cache files.
 allow system_server cache_file:dir { relabelfrom create_dir_perms };
 allow system_server cache_file:file { relabelfrom create_file_perms };
+allow system_server cache_file:fifo_file create_file_perms;
 
 # Run system programs, e.g. dexopt.
 allow system_server system_file:file x_file_perms;

uncrypt.te

@@ -14,11 +14,12 @@ userdebug_or_eng(`
   r_dir_file(uncrypt, shell_data_file)
 ')
 
-# Create tmp file /cache/recovery/command.tmp
 # Read /cache/recovery/command
-# Rename /cache/recovery/command.tmp to /cache/recovery/command
+# Read /cache/recovery/uncrypt_file
+# Write to pipe file /cache/recovery/uncrypt_status
 allow uncrypt cache_file:dir rw_dir_perms;
 allow uncrypt cache_file:file create_file_perms;
+allow uncrypt cache_file:fifo_file w_file_perms;
 
 # Set a property to reboot the device.
 set_prop(uncrypt, powerctl_prop)