[External] : Re: JEP411: Missing use-case: Monitoring / restricting libraries

[Peter Firmstone]

I had hoped by end of this discussion, that there would at least be an 
understanding of what OpenJDK is so hastily choosing to destroy.

Once it is gone, it will be irretrievable, it will never be possible to 
lock down the JVM so securely again.


On 21/05/2021 11:06 pm, Ron Pressler wrote:
>
>> On 21 May 2021, at 12:52, Peter Firmstone <peter.firmstone at zeus.net.au> wrote:
>>
>> It's quite clear this will be pushed through anyway,
>>
> No, not *anyway*, but given the fact that the community consists of millions of users, this
> proposal has been well-publicised,


I discovered the proposal on the 11th of the May on a mailing list I was 
subscribed to and I almost missed it.   Yes, it will be pushed through 
regardless, clearly the decision was made before publication.   Everyone 
saw applets coming, if the developers were serious about supporting 
applets, they would have designed a stripped down subset of Java, a JVM 
specifically suited that task which, didn't include things like XML or 
serialization.

Just think, Applets were killed because of their atrocious security.   
How ironic.


>> The granularity is not arbitrary, you said by class, which is incorrect.
>>
>> Granularity is by a combination of one or more of the following:
>>
>> 	• ProtectionDomain
>> 	• CodeSource
>> 	• Code signers
>> 	• ClassLoader
>> 	• Principals.
> What I said is correct. Assigning a ProtectionDomain to a class is possible, though not to a method
> (certainly not in code you can’t modify). In fact, ProtectionDomain is defined as “a set of classes,”
> i.e. class granularity. In particular, that is the granularity that instrumentation with doPrivileged
> aims to address, and that is one of the Security Manager’s most defining features.

It may be possible to assign a ProtectionDomain, to a single class, but 
that doesn't make your assertions correct, you should be quoting common 
use cases, I have never seen an example of assigning permissions to a 
single class, besides, it requires a dynamic policy to do that, and Java 
doesn't have one by default, so you can't use PolicyFile to assign it 
permissions.   Maybe you could use it to encapsulate ObjectInputStream 
with no permissions, then no one could grant it permissions, so that 
would be useful for Security.  It doesn't change class resolution or 
visibility. But OpenJDK didn't do that, why not?


What use case would there be to assign a ProtectionDomain to a method?

Just use a permission check in the method, or wrap a sensitive class 
with a decorator before publication:

http://svn.apache.org/viewvc/river/permission_delegates/src/main/java/org/apache/river/api/delegates/package.html?view=markup

But these are corner cases.

More useful cases are for isolation, such as JEE.


>
> Restricting access by principal at the application level does not require the Security Manager, so that
> part is irrelevant, and, in fact, not only Principal, but also Permission, and even CodeSource and
> ProtectionDomain are *not* being proposed for terminal deprecation or even deprecation by this JEP.


I guess your use case is a desktop application running in a single process?

What about a multi user server application running in a single 
process?   Now we have to spawn multiple processes for each user, that's 
hardly efficient or performant is it?


>
>> I would like to understand this pain that is being caused to a far greater number of people?   So far information has been scarce and it seems more of an excuse, as it's very light on detail.  I would guess it's the pain of having to update policy files and making sure tests pass with security enabled.
> The pain is that the high cost of maintaining the Security Manager comes at the expense of
> other security measures that, we believe, provide far more security value to the Java ecosystem
> as a whole.


Such as?


>> I think the results of locking down the JVM to principles of least privilege are totally worth it and a saleable commodity in the current global environment.
> I absolutely accept the principle of least privilege. I do not accept that the marginal cost/benefit
> of applying it at class granularity yields its best application.


I agree that there's little value for class granularity, but you are 
applying a corner case that although possible, is never applied in 
practice, and applying it with a broad brush, then using it as an 
argument against, please stop making this false assertion.   Just 
because you can do something, doesn't mean that you should.   Just 
because you can walk in front of a passing train, doesn't mean you 
should sir.

There is however a significant benefit for applying the principle of 
least privilege.

It can be assigned to Principal and Code signer granularity, that's 
actually quite coarse grained.  It's very flexible, unlike white listing 
Serializable classes.

>> Sure, theoretical things might, but there's no implementation in existence.  It has been quite affordable for me, so I wish to understand this pain, because I currently don't, I'm already using the latest encryption, static analysis, secure coding practices, validating input, sanitizing data etc.
> There are, though. Here are some: JFR, the module system, crypto protocols and ad-hoc mechanisms for
> specific vulnerable components (serialization, XML etc.). Maintaining the Security Manager comes at their
> expense -- some require urgent improvements like adding more events to JFR and closing down gaps in the
> module system’s defences -- and we believe investing in them has a better security ROI overall.

Don't be rude.  These are not alternatives, some are complementary, but 
not one provides the missing functionality.

And yuck, serialization, XML, vulnerable components should have been 
given un-privilged ProtectionDomains, so they couldn't do anything 
privileged while on the stack, like Perl Taint mode.   Or better yet 
alternative implementations created that practice data hygiene.

Java Serialization is a good example of good money thrown after bad, 
that has a far greater development cost.   Why did you (yes you OpenJDK) 
make Lambda's serializable?  Inner classes?  Yuck! Put it in a separate 
library, let people that use it download it, then the platform isn't 
made insecure for those who don't want it, this is a good use case for 
your new module system.

Once SecurityManager is gone, attackers will likely be able to bypass 
your feeble protections, such as whitelisting classes to be 
de-serialized; they only need to find a way to change a property prior 
to initialization, the first use of ObjectInputStream, which is quite 
easy if an application doesn't use it.  In future developers who don't 
use Java serialization will need to make sure it has been initialized so 
it can't be used as an attack vector, who will remember to do that?

>> Other techniques that are yet to be developed.   OpenJDK is deprecating SecurityManager prior to the implementation of it's replacement, a little more notice would have been nice.   I'm ready for you to deprecate Serialization, we saw that coming, but this is just completely unexpected out of left field.
> First, any deprecation proposal could be said to be unexpected until it is proposed. But that is why
> we have a deprecation policy that makes the process gradual and gives people time to adjust. Second, I
> don’t think this is "out of left field" at all. The writing on the wall was pretty clear when, after twenty-five
> years, few projects use the Security Manager and few libraries are properly instrumented for it, other platforms
> have decided not to adopt a similar model, and those few that have have already abandoned it some years ago.


Library's don't need to be instrumented for it, the Java platform is 
already and provides the necessary protection for network connections, 
file access and class loading for example.


- Peter.