RFR JDK-8233527: Update Lookup::hasPrivateAccess and Lookup::defineClass spec w.r.t. full power lookup

[Mandy Chung]

On 11/13/19 6:10 AM, Johannes Kuhn wrote:
> On 11.11.2019 22:23, Mandy Chung wrote:
>> This is a follow-up of JDK-8226916. Lookup::hasPrivateAccess intends 
>> to test if this lookup is a full-power lookup; that is created by the 
>> original caller class calling MethodHandles::lookup. The current 
>> specification for Lookup::hasPrivateAccess returns true if the lookup 
>> modes contain PRIVATE but it does not check MODULE bit.
>>
>> This patch also clarifies the capabilities w.r.t PRIVATE access and 
>> full-power access. The security permission check is performed if the 
>> Lookup is not a full power lookup and therefore Lookup::defineClass 
>> spec should be updated to perform security permission check if the 
>> security manager is present and this lookup refuses access, 
>> consistent with other Lookup operations.
>>
>> http://cr.openjdk.java.net/~mchung/jdk14/8233527/webrev.02/
>> http://cr.openjdk.java.net/~mchung/jdk14/8233527/specdiff/
>>
>> CSR: https://bugs.openjdk.java.net/browse/JDK-8233726
>>
>> thanks
>> Mandy
>
> Thank you for all those changes. It fixed two of my reported bugs 
> (JDK-8209005, JDK-8209078).

Thanks for filing these good reports.   JDK-8173978 resolved the issues 
reported by JDK-8209005 and JDK-8209078.

> It also makes my suggested workaround for JDK-8230636 not longer 
> possible. Thanks for picking that up too.
>
> I just have a question about the requirement of 
> MethodHandles.privateLookupIn: As it requires that the originating 
> lookup has both PRIVATE and MODULE access, it sounds a lot like full 
> privilege access. Should this be reworded?
>

The two bullets about the caller lookup object must have MODULE and 
PRIVATE are important explanation for it to require such access.

Maybe I can add a bullet to say "The caller lookup object must have full 
privilege access" and then move those two bullets as sub-bullets under it.

What do you think?

> Also, with the current specification, I don't see a way to abuse 
> jdk.unsupported's privileged access into java.base (which IMHO caused 
> the entire rework).

Thanks for looking at this.

Mandy