Add /dev/socket/uncrypt.

system_server used to communicate with uncrypt via files (e.g.
/cache/recovery/command and /cache/recovery/uncrypt_status). Since A/B
devices may not have /cache partitions anymore, we switch to communicate
via /dev/socket/uncrypt to allow things like factory reset to keep
working.

Bug: 27176738
Change-Id: I73b6d6f1ecdf16fd4f3600b5e524da06f35b5bca

file.te

@@ -206,6 +206,7 @@ type rild_socket, file_type;
 type rild_debug_socket, file_type;
 type system_wpa_socket, file_type;
 type system_ndebug_socket, file_type;
+type uncrypt_socket, file_type;
 type vold_socket, file_type;
 type wpa_socket, file_type;
 type zygote_socket, file_type;

file_contexts

@@ -116,6 +116,7 @@
 /dev/socket/racoon	u:object_r:racoon_socket:s0
 /dev/socket/rild	u:object_r:rild_socket:s0
 /dev/socket/rild-debug	u:object_r:rild_debug_socket:s0
+/dev/socket/uncrypt	u:object_r:uncrypt_socket:s0
 /dev/socket/vold	u:object_r:vold_socket:s0
 /dev/socket/wpa_eth[0-9] u:object_r:wpa_socket:s0
 /dev/socket/wpa_wlan[0-9] u:object_r:wpa_socket:s0

system_server.te

@@ -125,6 +125,7 @@ unix_socket_connect(system_server, zygote, zygote)
 unix_socket_connect(system_server, gps, gpsd)
 unix_socket_connect(system_server, racoon, racoon)
 unix_socket_send(system_server, wpa, wpa)
+unix_socket_connect(system_server, uncrypt, uncrypt)
 
 # Communicate over a socket created by surfaceflinger.
 allow system_server surfaceflinger:unix_stream_socket { read write setopt };

uncrypt.te

@@ -16,10 +16,11 @@ userdebug_or_eng(`
 
 # Read /cache/recovery/command
 # Read /cache/recovery/uncrypt_file
-# Write to pipe file /cache/recovery/uncrypt_status
 allow uncrypt cache_recovery_file:dir rw_dir_perms;
 allow uncrypt cache_recovery_file:file create_file_perms;
-allow uncrypt cache_recovery_file:fifo_file w_file_perms;
+
+# Write to /dev/socket/uncrypt
+unix_socket_connect(uncrypt, uncrypt, uncrypt)
 
 # Set a property to reboot the device.
 set_prop(uncrypt, powerctl_prop)