Finding the answer to this question should assist you to discover answers to many of the other questions you've had.
While I've done my best to answer as many of your questions as I can, time is limited and I haven't had time to answer all of them or rebutt or confirm all arguments / assumptions. Sometimes the right questions are more important than answers. Regards, Peter. Sent from my Samsung device. Include original message ---- Original message ---- From: Peter <j...@zeus.net.au> Sent: 15/02/2017 12:58:55 pm To: dev@river.apache.org <dev@river.apache.org> Subject: Re: OSGi NP Complete Was: OSGi - deserialization remote invocation strategy The PreferredClassLoader will attempt to download the jar file in order to get the preferred list. DownloadPermission should be called DefineClassPermission, I don't think it will prevent download of the jar per say. Why must the bootstrap proxy be loaded by the codebase ClassLoader? Regards, Peter. Sent from my Samsung device. Include original message ---- Original message ---- From: Michał Kłeczek <mic...@kleczek.org> Sent: 15/02/2017 06:20:37 am To: dev@river.apache.org Subject: Re: OSGi NP Complete Was: OSGi - deserialization remote invocation strategy So I've given it some thought and the only explanation I can come up with is: 1. To create an instance of the bootstrap proxy you need the codebase annotation. 2. Codebase annotation is needed because you want the bootstrap proxy's class to be defined in the proper codebase ClassLoader 3. Since you do not want to allow any code downloads before placing constraints on the bootstrap proxy - it has to be a dynamic proxy. That way its class can be defined by the codebase loader and yet no code is downloaded So the overall sequence is as follows: 1. Get the codebase annotation and create the codebase loader 2. Create an instance of a dynamic proxy of a class defined by the codebase loader 3. IMPORTANT - before creating the proxy instance DO NOT grant any download permissions - that way we are sure the proxy does not triggers any code download and execution due to it implementing some foreign interfaces 4. Once the proxy is instantiated - grant its ClassLoader download permissions 5. Place the constraints on the proxy 6. Invoke a remote method on the proxy I understand the whole thing is to make sure the bootstrap proxy is defined by the codebase ClassLoader - and the ClassLoader is needed to be able to dynamically grant download permissions. What I DO NOT understand is - why the download permissions are needed at all? Since the bootstrap proxy's code MUST be local code - why not simply have its class defined by the context ClassLoader? Since downloading code is done only after authentication anyway - I don't see the reason to use DownloadPermissions at all. The only thing that comes to mind is that it is to make sure the service is not able to download code from a codebase different than its own. Which is OK but redundant. The reasoning is: Since the code of the service proxy is already trusted (we have established trust before downloading it) - we can simply place the constraints on the service proxy that instructs it to only download code meeting certain criteria. Am I correct in my thinking? Thanks, Michal Michał Kłeczek wrote: > Let me dig some deeper. Comments inline. > > Peter wrote: >> Yes the dynamic proxy's are 100% local code. Remember dynamic >> proxy's don't have codebase s. :) > Of course they do - look at PreferredClassProvider - the dynamic proxy > class is defined by the codebase loader! > > Being a dynamic proxy does not mean there is no codebase. >> >> AtomicMarshalInputStream performs a special input validation on >> java.lang.reflect.Proxy thus ensuring the InvocationHandler is also >> trusted. If the InvocationHandler doesn't pass the test the proxy's >> never created. > Why does it only verify dynamic proxies? Doesn't it verify normal > objects? >> >> The dynamic proxy's put you in direct contact with the service >> provider using only local code with input validation constrained over >> secure connections (as configured with constraints in force). >> >> I think I've given you enough info now to investigate further. > Ok - so your "token" is the same thing as my SmartProxyWrapper. Let's > call it a "bootstrap proxy", ok? > > 1. What interface this bootstrap proxy implements? > 2. Why do you think it has to be a dynamic proxy (ie. an instance of a > subclass of java.lang.Proxy)? > 3. What and when are DownloadPermissions required? How do they add to > the overall security? > I understand the security of service proxies is enforced by the > constraints placed on the bootstrap proxy. > So where is the place for DownloadPermissions? > > 4. Finally - how is the lookup service proxy verified? Does it also > provide the bootstrap proxy? > If so - what special role does it play in the architecture? > The bootstrap proxy does not have to be provided by the lookup > service, does it? > > If it is verified differently - why and how? > > Thanks, > Michal
