Jconsole well known file is not secure in a relationship

Tsuna's blog: IOException: well-known file is not secure

jconsole well known file is not secure in a relationship

seven of the most popular NoSQL databases Xun (Brian) Wu, Sudarshan Kadambi, consists of , nodes, million relationships, and 3 million properties. adjusting the following line in the /etc/security/immobilier-haute-garonne.info file: * - nofile Graphite outbound JMX (not enabled by default) Backups. This is probably due to the file in /tmp used to communicate with the process having different permissions than the one the jstack gets. The file in question is. shares the vCloud Director database and an NFS file share (not shown). .. public network, including requests to JMX (port ) must be rejected by the firewall. provide a certificate signed by a well-known certificate authority (CA) for authentication, could potentially establish peering relationships.

The inclusion of supporting management services helps you build more powerful management solutions. Agent services are often themselves MBeans, which allow the agent and their functionality to be controlled through the MBean server. The JMX specification defines the following agent services: A dynamic class loading MLet management applet service: This allows for the retrieval and instantiation of new classes and native libraries from an arbitrary network location.

These observe an MBean attribute's numerical or string value, and can notify other objects of several types of changes in the target. These provide a scheduling mechanism based on a one-time alarm-clock notification or on a repeated, periodic notification. This service defines associations between MBeans and enforces consistency on the relationships.

Any JMX-compliant implementation will provide all of these agent services. However, JBoss does not rely on any of these standard agent services. The JBoss ClassLoader Architecture JBoss employs a class loading architecture that facilitates sharing of classes across deployment units and hot deployment of services and applications.

Before discussing the JBoss specific class loading model, we need to understand the nature of Java's type system and how class loaders fit in. Class Loading and Types in Java Class loading is a fundamental part of all server architectures. Arbitrary services and their supporting classes must be loaded into the server framework. This can be problematic due to the strongly typed nature of Java. Most developers know that the type of a class in Java is a function of the fully qualified name of the class.

However the type is also a function of the java. ClassLoader that is used to define that class. This additional qualification of type is necessary to ensure that environments in which classes may be loaded from arbitrary locations would be type-safe.

However, in a dynamic environment like an application server, and especially JBoss with its support for hot deployment are that class cast exceptions, linkage errors and illegal access errors can show up in ways not seen in more static class loading contexts.

Let's take a look at the meaning of each of these exceptions and how they can happen. ClassCastException results whenever an attempt is made to cast an instance to an incompatible type.

This trivial case is not what we are interested in however. Consider the case of a JAR being loaded by different class loaders. Although the classes loaded through each class loader are identical in terms of the bytecode, they are completely different types as viewed by the Java type system. ExObj class" ; Debug. InvocationTargetException [java] at sun. ClassCastException [java] at org. At line 55 of ExCCEc.

The ExObj passed in is the one loaded and created in lines via ucl0. The exception results when the ExCtx. To understand why this fails consider the debugging output from the chap2-ex0c. This is the class used to create the instance passed to the ExCtx. So even though the ExObj classes are the same in terms of actual bytecode since it comes from the same j0. Hence, attempting to cast an instance of ExObj from one scope to the other results in the ClassCastException.

This type of error is common when redeploying an application to which other applications are holding references to classes from the redeployed application. If you are redeploying an application, all dependent applications must flush their class references. Typically this requires that the dependent applications themselves be redeployed. An alternate means of allowing independent deployments to interact in the presence of redeployment would be to isolate the deployments by configuring the EJB layer to use the standard call-by-value semantics rather than the call-by-reference JBoss will default to for components collocated in the same VM.

IllegalAccessException - Doing what you should not A java. IllegalAccessException is thrown when one attempts to access a method or member that visibility qualifiers do not allow. Typical examples are attempting to access private or protected methods or instance variables. Another common example is accessing package protected methods or members from a class that appears to be in the correct package, but is really not due to caller and callee classes being loaded by different class loaders.

We will run this example to demonstrate how the IllegalAccessException can occur and then look at the specific issue with the example. Run the example using the following command: ExIAEd can not access a member of class org.

ExCtx with modifiers "" [java] at sun. At line 48 of ExIAEd. The pkgUseValue method has package protected access and even though both the invoking class ExIAEd and the ExCtx class whose method is being invoked reside in the org. This can be seen by looking at the debugging output from the chap2-ex0d. The ExIAEd class is seen to have been loaded via the default application class loader instance sun.

Because the classes are loaded by different class loaders, access to the package protected method is seen to be a security violation. So, not only is type a function of both the fully qualified class name and class loader, the package scope is as well. An example of how this can happen in practice is to include the same classes in two different SAR deployments. If classes in the deployment have a package protected relationship, users of the SAR service may end up loading one class from SAR class loading at one point, and then load another class from the second SAR at a later time.

If the two classes in question have a protected access relationship an IllegalAccessError will result. The solution is to either include the classes in a separate jar that is referenced by the SARs, or to combine the SARs into a single deployment. LinkageErrors - Making Sure You Are Who You Say You Are Loading constraints validate type expectations in the context of class loader scopes to ensure that a class X is consistently the same class when multiple class loaders are involved.

This is important because Java allows for user defined class loaders. Linkage errors are essentially an extension of the class cast exception that is enforced by the VM when classes are loaded and used. To understand what loading constraints are and how they ensure type-safety we will first introduce the nomenclature of the Liang and Bracha paper along with an example from this paper. There are two type of class loaders, initiating and defining. An initiating class loader is one that a ClassLoader.

A defining class loader is the loader that calls one of the ClassLoader.

jconsole well known file is not secure in a relationship

In the latter case, there is still a defining class loader, it's just not important what the identity of the defining class loader is. The only time the initiating loader is relevant is when a loading constraint is being validated.

Since Delegated is defined by L2, L2 will be used to initiate loading of Spoofed in the context of the Delegated. Java addresses this problem by generating loader constraints to validate type consistency when the types being used are coming from different defining class loaders.

It does not matter if L1 or L2, or even some other class loader defines Spoofed. All that matters is that there is only one Spoofed class defined regardless of whether L1 or L2 was used to initiate the loading.

jconsole well known file is not secure in a relationship

If L1 or L2 have already defined separate versions of Spoofed when this check is made a LinkageError will be generated immediately. Otherwise, the constraint will be recorded and when Delegated. Now let's take a look at how a LinkageError can occur with a concrete example. A concrete example of a LinkageError package org.

This class loader implementation overrides the default parent delegation model to allow the ucl0 and ucl1 instances to both load the ExObj2 class and then setup a delegation relationship from ucl0 to ucl1. At lines 30 and At line 45 of ExLE. At this point both the ucl0 and ucl1 class loaders have defined the ExObj2 class.

A delegation relationship from ucl0 to ucl1 is then setup at line 51 via the ucl0. Finally, at line 54 of ExLE. Because we have loaded ExObj2 using both ucl0 and ucl1 prior to setting up the delegation relationship, the constraint will be violated and should generate a LinkageError when run.

Debugging Class Loading Issues Debugging class loading issues comes down to finding out where a class was loaded from. Debug class of the book examples. The first is that every Class object knows its defining ClassLoader and this is available via the getClassLoader method.

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The defines the scope in which the Class type is known as we have just seen in the previous sections on class cast exceptions, illegal access exceptions and linkage errors. From the ClassLoader you can view the hierarchy of class loaders that make up the parent delegation chain. The defining ClassLoader of a Class cannot tell you from what location that Class was loaded. To determine this you must obtain the java.

ProtectionDomain and then the java. Note that not every Class has a CoPdeSource. If a class is loaded by the bootstrap class loader then its CodeSource will be null. This will be the case for all classes in the java. Beyond that it may be useful to view the details of classes being loaded into the JBoss server.

Although it may not be meaningful if you have not looked at the class loading code, it is vital information needed for submitting bug reports or questions regarding class loading problems. Inside the JBoss Class Loading Architecture Now that we have the role of class loaders in the Java type system defined, let's take a look at the JBoss class loading architecture. The core JBoss class loading components The central component is the org.

This is an extension of the standard java. URLClassLoader that overrides the standard parent delegation model to use a shared repository of classes and resources.

jconsole well known file is not secure in a relationship

This shared repository is the org. Deployers use the top-level deployment's UCL as a shared class loader and all deployment archives are assigned to this class loader. When a UCL is asked to load a class, it first looks to the repository cache it is associated with to see if the class has already been loaded. Only if the class does not exist in the repository will it be loaded into the repository by the UCL. This means the UCLs form a single flat class loader namespace. The complete sequence of steps that occur when a UnfiedClassLoader3.

If the class is found in the cache it is returned. Else, ask the UnfiedClassLoader3 if it can load the class. If the class is found it is placed into the repository classes cache and returned. Else, the repository is queried for all UCLs that are capable of providing the class based on the repository package name to UCL map.

This allows for a quick determination of which UCLs are capable of loading the class. If a UCL is found that can load the class it is returned, else a java. This is an MBean that contains operations to display class and package information.

The getPackageClassLoaders operation returns a set of class loaders that have been indexed to contain classes or resources for the given package name. The package name must have a trailing period. If you type in the package name org. It is the class loader that owns all of the JARs in the lib directory of the server configuration e.

The view the information for a given class, use the displayClassInfo operation, passing in the fully qualified name of the class to view. For example, if we use org. HtmlAdaptorServlet which is from the package we just looked at, the following description is displayed: The information is a dump of the information for the Class instance in the loader repository if one has been loaded, followed by the class loaders that are seen to have the class file available.

If a class is seen to have more than one class loader associated with it, then there is the potential for class loading related errors. Scoping Classes If you need to deploy multiple versions of an application you need to use deployment based scoping.

jconsole well known file is not secure in a relationship

With deployment based scoping, each deployment creates its own class loader repository in the form of a HeirarchicalLoaderRepository3 that looks first to the UnifiedClassLoader3 instances of the deployment units included in the EAR before delegating to the default UnifiedLoaderRepository3. The Complete Class Loading Model The previous discussion of the core class loading components introduced the custom UnifiedClassLoader3 and UnifiedLoaderRepository3 classes that form a shared class loading space.

The complete class loading picture must also include the parent class loader used by UnifiedClassLoader3s as well as class loaders introduced for scoping and other specialty class loading purposes. A complete class loader view The following points apply to this figure: The System ClassLoaders node refers to either the thread context class loader TCL of the VM main thread or of the thread of the application that is loading the JBoss server if it is embedded.

All URLs referenced via the jboss. These are path specifications relative to the libraryURL defined by the jboss. If there is no jboss. The default is crimson. Oswego concurrency classes JAR, concurrent. The Server node represent a collection of UCLs created by the org. The default implementation creates UCLs for the patchDir entries as well as the server conf directory. This is a flat namespace and there should not be multiple instances of a class in different deployment JARs.

If there are, only the first loaded will be used and the results may not be as expected. Use this mechanism if you need to deploy multiple versions of a class in a given JBoss server. If the WebService is configured to allow system level classes to be loaded, all classes in the UnifiedLoaderRepository3 as well as the system classpath are available via HTTP.

If the servlet 2. Further, JMX aims to provide integration with the large number of existing management standards. The three levels are: The Relationship between the components of the JMX architecture 2. Instrumentation Level The instrumentation level defines the requirements for implementing JMX manageable resources. A JMX manageable resource can be virtually anything, including applications, service components, devices, and so on.

The manageable resource exposes a Java object or wrapper that describes its manageable features, which makes the resource instrumented so that it can be managed by JMX-compliant applications. The user provides the instrumentation of a given resource using one or more managed beans, or MBeans. There are four varieties of MBean implementations: The instrumentation level also specifies a notification mechanism.

The purpose of the notification mechanism is to allow MBeans to communicate changes with their environment. This is similar to the JavaBean property change notification mechanism, and can be used for attribute change notifications, state change notifications, and so on. Agent Level The agent level defines the requirements for implementing agents. Agents are responsible for controlling and exposing the managed resources that are registered with the agent. By default, management agents are located on the same hosts as their resources.

This collocation is not a requirement. The agent requirements make use of the instrumentation level to define a standard MBeanServer management agent, supporting services, and a communications connector. JBoss provides both an html adaptor as well as an RMI adaptor. A JMX agent does not need to know which resources it will serve. The agent does not need to know anything about the connectors or management applications that interact with the agent and its MBeans.

Distributed Services Level The JMX specification notes that a complete definition of the distributed services level is beyond the scope of the initial version of the JMX specification. The general purpose of this level is to define the interfaces required for implementing JMX management applications or managers. The following points highlight the intended functionality of the distributed services level as discussed in the current JMX specification.

Provide an interface for management applications to interact transparently with an agent and its JMX manageable resources through a connector Exposes a management view of a JMX agent and its MBeans by mapping their semantic meaning into the constructs of a data-rich protocol for example HTML or SNMP Distributes management information from high-level management platforms to numerous JMX agents Consolidates management information coming from numerous JMX agents into logical views that are relevant to the end user's business operations Provides security It is intended that the distributed services level components will allow for cooperative management of networks of agents and their resources.

These components can be expanded to provide a complete management application. JMX Component Overview This section offers an overview of the instrumentation and agent level components. The instrumentation level components include the following: MBeans standard, dynamic, open, and model MBeans Notification model elements The agent level components include: MBean server Agent services 2. The MBean for a resource exposes all necessary information and operations that a management application needs to control the resource.

The scope of the management interface of an MBean includes the following: Attribute values that may be accessed by name Operations or functions that may be invoked Notifications or events that may be emitted The constructors for the MBean's Java class JMX defines four types of MBeans to support different instrumentation needs: These use a simple JavaBean style naming convention and a statically defined management interface.

This is the most common type of MBean used by JBoss.

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These must implement the javax. DynamicMBean interface, and they expose their management interface at runtime when the component is instantiated for the greatest flexibility. JBoss makes use of Dynamic MBeans in circumstances where the components to be managed are not known until runtime.

These are an extension of dynamic MBeans. Open MBeans rely on basic, self-describing, user-friendly data types for universal manageability.

These are also an extension of dynamic MBeans. Model MBeans must implement the javax. Model MBeans simplify the instrumentation of resources by providing default behavior. We will present an example of a Standard and a Model MBean in the section that discusses extending JBoss with your own custom services.

Both the MBean server and MBeans can send notifications to provide information. The JMX specification defines the javax. The specification also defines the operations on the MBean server that allow for the registration of notification listeners.

Users can obtain a common metadata view of any of the four MBean types by querying the MBean server with which the MBeans are registered. The metadata classes cover an MBean's attributes, operations, notifications, and constructors. For each of these, the metadata includes a name, a description, and its particular characteristics.

For example, one characteristic of an attribute is whether it is readable, writable, or both. The metadata for an operation contains the signature of its parameter and return types. The different types of MBeans extend the metadata classes to be able to provide additional information as required. This common inheritance makes the standard information available regardless of the type of MBean.

A management application that knows how to access the extended information of a particular type of MBean is able to do so. MBean Server A key component of the agent level is the managed bean server. Its functionality is exposed through an instance of the javax. An MBean server is a registry for MBeans that makes the MBean management interface available for use by management applications. The MBean never directly exposes the MBean object itself; rather, its management interface is exposed through metadata and operations available in the MBean server interface.

This provides a loose coupling between management applications and the MBeans they manage. MBeans can be instantiated and registered with the MBeanServer by the following: Another MBean The agent itself A remote management application through the distributed services When you register an MBean, you must assign it a unique object name.

The object name then becomes the unique handle by which management applications identify the object on which to perform management operations. The operations available on MBeans through the MBean server include the following: Discovering the management interface of MBeans Reading and writing attribute values Invoking operations defined by MBeans Registering for notifications events Querying MBeans based on their object name or their attribute values Protocol adaptors and connectors are required to access the MBeanServer from outside the agent's JVM.

Each adaptor provides a view via its protocol of all MBeans registered in the MBean server the adaptor connects to. Later versions of the specification will address the need for remote access protocols in standard ways. A connector is an interface used by management applications to provide a common API for accessing the MBean server in a manner that is independent of the underlying communication protocol.

Each connector type provides the same remote interface over a different protocol. This allows a remote management application to connect to an agent transparently through the network, regardless of the protocol. The specification of the remote management interface will be addressed in a future version of the JMX specification. Adaptors and connectors make all MBean server operations available to a remote management application.

For an agent to be manageable from outside of its JVM, it must include at least one protocol adaptor or connector. The inclusion of supporting management services helps you build more powerful management solutions.

Agent services are often themselves MBeans, which allow the agent and their functionality to be controlled through the MBean server. The JMX specification defines the following agent services: A dynamic class loading MLet management applet service: This allows for the retrieval and instantiation of new classes and native libraries from an arbitrary network location. These observe an MBean attribute's numerical or string value, and can notify other objects of several types of changes in the target.

These provide a scheduling mechanism based on a one-time alarm-clock notification or on a repeated, periodic notification. This service defines associations between MBeans and enforces consistency on the relationships. Any JMX-compliant implementation will provide all of these agent services.

However, JBoss does not rely on any of these standard agent services. Before discussing the JBoss specific class loading model, we need to understand the nature of Java's type system and how class loaders fit in. Class Loading and Types in Java Class loading is a fundamental part of all server architectures. Arbitrary services and their supporting classes must be loaded into the server framework.

This can be problematic due to the strongly typed nature of Java. Most developers know that the type of a class in Java is a function of the fully qualified name of the class. As of Java 1. ClassLoader that is used to define that class. This additional qualification of type was added to ensure that environments in which classes may be loaded from arbitrary locations would be type-safe. A paper entitled Java is not type-safe by Vijay Saraswat in demonstrated that Java was not type-safe as intended.

This could allow one to gain access to method and members of a class to which they should not have had access by fooling the Java VM into using an alternate implementation of a previously loaded class. Such circumvention of the type system was based on introducing class loaders that by-pass the normal delegation model.

A class loader uses a delegation model to search for classes and resources. Each instance of ClassLoader has an associated parent class loader that is either explicitly set when it is created, or assigned by the VM if no parent was specified. When called upon to find a class, a class loader will typically delegate the search for the class to its parent class loader before attempting to find the class or resource itself.

The VM has a root class loader, called the bootstrap class loader, does not have a parent but may serve as the parent of a ClassLoader instance. To address the type-safety issue, the type system was strengthened to include a class's defining ClassLoader in addition to the name of the class to fully define the type. The ramifications of this change in a dynamic environment like an application server, and especially JBoss with its support for hot deployment are that class cast exectiontions, linkage errors and illegal access errors can show up in ways not seen in more static class loading contexts.

Let's take a look at the meaning of each of these exceptions and how they can happen. ClassCastException results whenever an attempt is made to cast an instance to an incompatible type. This trivial case is not what we are interested in however. Consider the case of a JAR being loaded by differendt class loaders. Although the classes loaded through each class loader are identical in terms of the bytecode, they are completely different types as viewed by the Java type system.

jconsole well known file is not secure in a relationship

ExObj class" ; Debug. The ExObj and ExObj2 classes used in the examples package org. InvocationTargetException [java] at sun.

ClassCastException [java] at org. At line 55 of ExCCEc. The ExObj passed in is the one loaded and created in lines via ucl0. The exception results when the ExCtx. To understand why this fails consider the debugging output from the chap2-ex0c.

This is the class used to create the instance passed to the ExCtx. So even though the ExObj classes are the same in terms of actual bytecode since it comes from the same j0.

Hence, attempting to cast an instance of ExObj from one scope to the other results in the ClassCastException. This type of error is common when one redeploys an application to which other applications are holding references to classes from the redeployed application.

If you are redeploying an application, all dependent applications must flush their class references. Typically this requires that the dependent applications themselves be redeployed. An alternate means of allowing independent deployments to interact in the presence of redeployment would be to isolate the deployments by configuring the EJB layer to use the standard call-by-value semantics rather than the call-by-reference JBoss will default to for components collocated in the same VM.

IllegalAccessException - Doing what you should not A java. IllegalAccessException is thrown when one attempts to access a method or member that visibility qualifiers do not allow.