am a8e073cd: Create boot_block_device and allow install_recovery read access

* commit 'a8e073cd':
  Create boot_block_device and allow install_recovery read access

device.te

@@ -76,6 +76,9 @@ type system_block_device, dev_type;
 # Recovery block device.
 type recovery_block_device, dev_type;
 
+# boot block device.
+type boot_block_device, dev_type;
+
 # Userdata block device mounted on /data.
 type userdata_block_device, dev_type;
 

install_recovery.te

@@ -13,8 +13,9 @@ allow install_recovery shell_exec:file rx_file_perms;
 # Execute /system/bin/applypatch
 allow install_recovery system_file:file rx_file_perms;
 
-# Update the recovery block device
+# Update the recovery block device based off a diff of the boot block device
 allow install_recovery block_device:dir search;
+allow install_recovery boot_block_device:blk_file r_file_perms;
 allow install_recovery recovery_block_device:blk_file rw_file_perms;
 
 # Create and delete /cache/saved.file