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From "lionel gomez (JIRA)" <>
Subject [jira] Created: (HIVEMIND-192) Using tapestry 4.0 with java 2 security enabled prevents the application from starting on several application servers (solution proposed)
Date Wed, 15 Nov 2006 02:19:39 GMT
Using tapestry 4.0 with java 2 security enabled prevents the application from starting on several
application servers (solution proposed)

                 Key: HIVEMIND-192
             Project: HiveMind
          Issue Type: Bug
    Affects Versions: 1.1
         Environment: java version 1.4.1_07 , apache tomcat server, 5.0  IBM Websphere server
            Reporter: lionel gomez

problem: Using tapestry 4.0 with java 2 security enabled on several application servers prevents
the application from starting 

The SecurityManager do security checks for sensitive operation based on context of the current
execution thread and its execution stack. The AccessControlContext obtains a stack of ProtectionDomains
of all objects in the execution stack and checks if all these ProtectionDomain have all the
permision required to perform the operation. 

Tapestry/Hivemind uses javassist library to create enhaced pages and components using bytecode
manipulation and generates a ctClass object, then use HivemindPool wich ends up in a call
to ClassPool.toClass(CtClass). 
Javassist uses reflection to make a call to ClassLoader.defineClass(String name, byte[] b,
int off, int len) wich generates an object with a default ProtectionDomain. So pages and componentes
will have the default ProtectionDomain. 

copied from java API: 
This method assigns a default ProtectionDomain to the newly defined class. The ProtectionDomain
is effectively granted the same set of permissions returned when Policy.getPolicy().getPermissions(new
CodeSource(null, null)) is invoked. 

When the AccessControlContext do the security checks on the ProtectionDomain of these enhaced
classes it fails to find the required permisions, because they dont have any permision (or
protectiondomain is null cant remember for sure any way fails to find required permisions).

The solution is to instead use the method ClassLoader.defineClass(String name, byte[] b, int
off, int len, ProtectionDomain protectionDomain) this way we can assign a ProtectionDomain
that has the defined permisions in the policy. 

So this is really a javassist problem not a Tapestry/Hivemind problem. 

But fixing this in javassist is not easy. The ctClass class deal with bytecode manipulation
only, and the ProtectionDomain is a responsability of the ClassLoader. Should javassist also
take over the ClassLoader responsibility of assigning ProtectionDomains and get the assigned
permisions from policy. What ProtectionDomain should a new set of bytecode have if made with
makeClass() ? 

Until javassist solves this in another realease and this realease is included in another tapestry
release, a solution is to modify the class HivemindPool. We have used this and work fine.
it works without modifying javassist. 

Proposed Solution: 
1. Modifyng the HivemindClassPool class to assign the ProtectionDomain of the classloader
or the HivemindClassPool to all the enhanced classes. 
2. Rebuild the hivemind.jar 
3. Modify the security policy file that grants the required permision for the application.
(start by granting all permisions to test and then replace with the fine grained ones) 

This makes all enhaced class to have a ProtectionDomain with permisions granted on the policy
file. Non enhaced classes will still have the fine grained permisions specified in the policy
file, but enhaced class will have the same permision granted to the HivemindClassPool. 

In file org.apache.hivemind.service.impl.HiveMindClassPool replace the following : 

 public Class toClass(CtClass ctClass) throws CannotCompileException 
       return ctClass.toClass(_loader); 

with the following: 
It uses the other method of ClassLoader and pass the ProtectionDomain of the HivemindClassPool.

 public Class toClass(CtClass ctClass) throws CannotCompileException 
return toClass(ctClass, _loader); 

    public Class toClass(CtClass ct, ClassLoader loader) 
    throws CannotCompileException 
    try { 
        byte[] b = ct.toBytecode(); 
        Class cl = Class.forName("java.lang.ClassLoader"); 
        java.lang.reflect.Method method = 
                            new Class[] { String.class, byte[].class, 
                                          int.class, int.class, ProtectionDomain.class });

        Object[] args = new Object[] { ct.getName(), b, new Integer(0), 
                                       new Integer(b.length), this.getClass().getProtectionDomain()};

        Class clazz = (Class)method.invoke(loader, args); 
        return clazz; 
    catch (RuntimeException e) { 
        throw e; 
    catch (java.lang.reflect.InvocationTargetException e) { 
        throw new CannotCompileException(e.getTargetException()); 
    catch (Exception e) { 
        throw new CannotCompileException(e); 

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