On Dec 15, 2007, at 5:54 AM, Rob Austin wrote:
Hi,
I am currently looking at the extent to which AspectJ can be used to
enhance object security.
A good application, but I wouldn't just rely on AJ to solve it! ;)
If I write a pointcut that allows me to trap all calls to the public
methods of my objects outside of the package it resides on, I can
monitor these calls and make sure they are legal, or at least
acceptable,and through reflection I can tell which objects are
calling these methods.
Yes
But I understand that its possible (even though I wouldn't have a
clue how to do it) for one object to call a public method of
another object loaded in the same JVM through introspecting the
classloader. In other words there would be no matches on the
pointcuts at compile time and the advices would not expect to be
applied. So, what would happen at runtime if one object "illegally"
called another's method? Is there any further runtime checking which
would allow the advice to be matched?
It's true that using reflection would "bypass" the pointcut. This is
true because the reflection calls will refer to the classes and
methods by name (as a string), so the invocations will be "invisible"
to AJ. However, if you want to prevent all reflection calls, you could
write a pointcut that looks for anyone calling the reflection API and
raise an exception. In fact, for this task and your original plan, you
can write an aspect that will detect these calls at compile time!
aspect NoReflectionForYou {
pointcut allReflectionCalls(): call(*
java.lang.reflect..*.*(..));
declare error: allReflectionCalls(): "No reflection for you!!";
}
You can also use declare error to prevent calls to objects in package
A from the within objects in package B, for example.
If you don't want to prevent all reflection calls from your code, but
only those to "sensitive" areas, you could write an aspect that
advices specific reflection calls, e.g., calls to the Method class,
and look at the method name to pick out the ones you want to prevent.
Hope this helps.
dean
Apologies if this question is full of hypotheticals (I know that 2
java programs would normally be launched in seprate JVMs!).
Thanks
Rob
_______________________________________________
aspectj-users mailing list
[email protected]
https://dev.eclipse.org/mailman/listinfo/aspectj-users
Dean Wampler, Ph.D.
dean at objectmentor.com
http://www.objectmentor.com
See also:
http://www.aspectprogramming.com AOP advocacy site
http://aquarium.rubyforge.org AOP for Ruby
http://www.contract4j.org Design by Contract for Java5
_______________________________________________
aspectj-users mailing list
[email protected]
https://dev.eclipse.org/mailman/listinfo/aspectj-users
