java.security

Class Policy


public abstract class Policy
extends Object

This is an abstract class for representing the system security policy for a Java application environment (specifying which permissions are available for code from various sources). That is, the security policy is represented by a Policy subclass providing an implementation of the abstract methods in this Policy class.

There is only one Policy object in effect at any given time.

The source location for the policy information utilized by the Policy object is up to the Policy implementation. The policy configuration may be stored, for example, as a flat ASCII file, as a serialized binary file of the Policy class, or as a database.

The currently-installed Policy object can be obtained by calling the getPolicy() method, and it can be changed by a call to the setPolicy() method (by code with permission to reset the Policy).

The refresh() method causes the policy object to refresh / reload its current configuration.

This is implementation-dependent. For example, if the policy object stores its policy in configuration files, calling refresh() will cause it to re-read the configuration policy files. The refreshed policy may not have an effect on classes in a particular ProtectionDomain. This is dependent on the Policy provider's implementation of the implies() method and the PermissionCollection caching strategy.

The default Policy implementation can be changed by setting the value of the "policy.provider" security property (in the Java security properties file) to the fully qualified name of the desired Policy implementation class. The Java security properties file is located in the file named <JAVA_HOME>/lib/security/java.security , where <JAVA_HOME> refers to the directory where the SDK was installed.

IMPLEMENTATION NOTE: This implementation attempts to read the System property named policy.provider to find the concrete implementation of the Policy. If/when this fails, it falls back to a default implementation, which allows everything.

Since:
1.2
See Also:
CodeSource, PermissionCollection, SecureClassLoader

Constructor Summary

Policy()
Constructs a new Policy object.

Method Summary

abstract PermissionCollection
getPermissions(CodeSource codesource)
Evaluates the global policy and returns a PermissionCollection object specifying the set of permissions allowed for code from the specified code source.
PermissionCollection
getPermissions(ProtectionDomain domain)
Evaluates the global policy and returns a PermissionCollection object specifying the set of permissions allowed given the characteristics of the protection domain.
static Policy
getPolicy()
Returns the installed Policy object.
boolean
implies(ProtectionDomain domain, Permission permission)
Evaluates the global policy for the permissions granted to the ProtectionDomain and tests whether the permission is granted.
abstract void
refresh()
Refreshes/reloads the policy configuration.
static void
setPolicy(Policy policy)
Sets the system-wide Policy object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Policy

public Policy()
Constructs a new Policy object.

Method Details

getPermissions

public abstract PermissionCollection getPermissions(CodeSource codesource)
Evaluates the global policy and returns a PermissionCollection object specifying the set of permissions allowed for code from the specified code source.
Parameters:
codesource - the CodeSource associated with the caller. This encapsulates the original location of the code (where the code came from) and the public key(s) of its signer.
Returns:
the set of permissions allowed for code from codesource according to the policy. The returned set of permissions must be a new mutable instance and it must support heterogeneous Permission types.

getPermissions

public PermissionCollection getPermissions(ProtectionDomain domain)
Evaluates the global policy and returns a PermissionCollection object specifying the set of permissions allowed given the characteristics of the protection domain.
Parameters:
domain - the ProtectionDomain associated with the caller.
Returns:
the set of permissions allowed for the domain according to the policy. The returned set of permissions must be a new mutable instance and it must support heterogeneous Permission types.
Since:
1.4

getPolicy

public static Policy getPolicy()
Returns the installed Policy object. This value should not be cached, as it may be changed by a call to setPolicy(). This method first calls SecurityManager.checkPermission(Permission) with a SecurityPermission("getPolicy") permission to ensure it's ok to get the Policy object.
Returns:
the installed Policy.
Throws:
SecurityException - if a security manager exists and its checkPermission() method doesn't allow getting the Policy object.

implies

public boolean implies(ProtectionDomain domain,
                       Permission permission)
Evaluates the global policy for the permissions granted to the ProtectionDomain and tests whether the permission is granted.
Parameters:
domain - the ProtectionDomain to test.
permission - the Permission object to be tested for implication.
Returns:
true if permission is a proper subset of a permission granted to this ProtectionDomain.
Since:
1.4

refresh

public abstract void refresh()
Refreshes/reloads the policy configuration. The behavior of this method depends on the implementation. For example, calling refresh on a file-based policy will cause the file to be re-read.

setPolicy

public static void setPolicy(Policy policy)
Sets the system-wide Policy object. This method first calls SecurityManager.checkPermission(Permission) with a SecurityPermission("setPolicy") permission to ensure it's ok to set the Policy.
Parameters:
policy - the new system Policy object.
Throws:
SecurityException - if a security manager exists and its checkPermission() method doesn't allow setting the Policy.

Policy.java --- Policy Manager Class Copyright (C) 1999, 2003, 2004 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.