8196830: publicLookup().findVirtual should not return method handle to AccessibleObject.setAccessible

[mandy chung]

This patch looks good.  It's unfortunate that setAccessible was not final
to begin with.  I agree that this fix is a good compromise with a simple
fix and low incompatibility.   Is there a CSR to review?

Mandy

On 2/19/18 8:57 AM, Alan Bateman wrote:
>  > AccessibleObject's setAccessible(boolean) is currently not caller > 
sensitive but the overrides in Method/Field/Constructor are. This > 
awkwardness stems from its constructor being protected and the method > 
not being final. It is thus possible to extend the class outside of > 
the java.lang.reflect package and override this method (at least one > 
popular library does this). Ideally the constructor should have been > 
package private and/or the method be final but it's not possible to > 
change this after 20 years. > > The consequence of the method in the 
base class not being caller > sensitive is that it's possible to use a 
minimally trusted lookup to > get a method handle to the method. Paul, 
Mandy and I chatted about > this one recently. We prototyped changes to 
the MH implementation to > special case this method and treat it "as if" 
it is caller sensitive. > This maximizes compatibility but has the 
downside that it makes it > harder to audit and somewhat fragile. In the 
end, we concluded it > would be simpler to add the @CS annotation to 
this method so that it > is treated consistently. The downside of this 
is that custom > AccessibleObject implementations need to override 
setAccessible if > they want to be invoked using method handles obtained 
from a > minimally trusted lookup. > > The proposed changes are simple. 
The removal of "checkMemberAccess" > from canBeCalledVirtual is just a 
clean-up because this method is no > longer needs special casing (it was 
degraded for Java SE 10 as > envisaged in JEP 176). It's not the goal 
here to improve the > performance of canBeCalledVirtual but there may be 
opportunities to > look at that with a separate issue: > 
http://cr.openjdk.java.net/~alanb/8196830/webrev/ > > -Alan