Best approach to sandboxing Nashorn

A. Sundararajan sundararajan.athijegannathan at
Mon Sep 16 21:18:19 PDT 2013

I forgot to add. Nashorn does not contain any builtin module system. 
But, if a module system is pure JS + Java, it must be possible to run on 

Nashorn supports "load" (loads scripts from URL, File, resources) and 
"loadWithNewGlobal" (loads script but into a fresh global scope) 
primitives in addition to the good old 'eval'. So, it should be possible 
for any module system to be implemented on top of nashorn in pure JS or 
perhaps with a bit of Java code.


On Tuesday 17 September 2013 09:40 AM, A. Sundararajan wrote:
> Hi,
> * Nashorn already filters classes - only public classes of 
> non-sensitive packages (packages listed in package.access security 
> property aka 'sensitive'). Package access check is done from a 
> no-permissions context. i.e., whatever package that can be accessed 
> from a no-permissions class are only allowed.
> * Nashorn filters Java reflective and jsr292 access - unless script 
> has RuntimePermission("nashorn.JavaReflection"), the script wont be 
> able to do reflection.
> * The above two require running with SecurityManager enabled. Under no 
> security manager, the above filtering won't apply.
> * You could remove global Java.type function and Packages object (+ 
> com,edu,java,javafx,javax,org,JavaImporter) in global scope and/or 
> replace those with whatever filtering functions that you implement. 
> Because, these are the only entry points to Java access from script, 
> customizing these functions => filtering Java access from scripts.
> * There is an undocumented option (right now used only to run test262 
> tests) "--no-java" of nashorn shell that does the above for you. i.e., 
> Nashorn won't initialize Java hooks in global scope.
> * JSR223 does not provide any standards based hook to pass a custom 
> class loader. This may have to be addressed in a (possible) future 
> update of jsr223.
> Hope this helps,
> -Sundar
> On Tuesday 17 September 2013 09:17 AM, Rod Nim wrote:
>> Hi Nashorn team!
>> Are there any recommendations for the best way to restrict the 
>> classes that Nashorn scripts can create to a whitelist? Or is the 
>> approach the same as any JSR223 engine (custom classloader on the 
>> ScriptEngineManager constructor)?
>> I'm also wondering if you have any tips on managing script .js 
>> dependencies; like RequireJS, npm etc?
>> Thanks in advance!
>> Rod

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