Let’s say I have an existing application written in Java which I wish to add scripting support to. This is fairly trivial with Groovy (and just as trivial in .Net with any of the Iron range of dynamic languages).
As trivial as adding the support is, it raises a whole host of questions about script execution and security – and how to implement that security.
Has anyone come across any interesting articles/papers or have any insights into this that they’d like to share? In particular I’d be very interested in architectural things like execution contexts, script authentication, script signing and things along those lines… you know, the kind of stuff that prevents users from running arbitrary scripts they just happened to download which managed to screw up their entire application, whilst still allowing scripts to be useful and flexible.
Quick Edit
I’ve mentioned signing and authentication as different entities because I see them as different aspects of security.
For example, as the developer/supplier of the application I distribute a signed script. This script is legitimately ‘data destructive’ by design. Such as it’s nature, it should only be run by administrators and therefore the vast majority of users/system processes should not be able to run it. This being the case it seems to me that some sort of security/authentication context is required based on the actions the script performs and who is running that script.
You may have a look at the documentation on security: http://groovy.codehaus.org/Security Basically, you can use the usual Java Security Manager.
And beyond this, there’s a sample application showing how you can introspect the code by analyzing its AST (Abstract Syntax Tree) at compile-time, so that you can allow / disallow certain code constructs, etc. Here’s an example of an arithmetic shell showing this in action: http://svn.groovy.codehaus.org/browse/groovy/trunk/groovy/groovy-core/src/examples/groovyShell