java.lang.SecurityManager
is new.
java.lang.Object
The security manager is a class that allows applications to implement a security policy. It allows an application to determine, before performing a possibly unsafe or sensitive operation, what the operation is and whether it is being attempted in a security context that allows the operation to be performed. The application can allow or disallow the operation.
The SecurityManager class contains many methods with names that begin with the word check. These methods are called by various methods in the Java libraries before those methods perform certain potentially sensitive operations. The invocation of such a check method typically looks like this:
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkXXX(argument, . . . );
}
The security manager is thereby given an opportunity to prevent completion of the operation by throwing an exception. A security manager routine simply returns if the operation is permitted, but throws a SecurityException if the operation is not permitted. The only exception to this convention is checkTopLevelWindow, which returns a boolean value.
The current security manager is set by the setSecurityManager method in class System. The current security manager is obtained by the getSecurityManager method.
The special method checkPermission(java.security.Permission) determines whether an access request indicated by a specified permission should be granted or denied. The default implementation calls
AccessController.checkPermission(perm);
If a requested access is allowed, checkPermission returns quietly. If denied, a SecurityException is thrown.
As of Java 2 SDK v1.2, the default implementation of each of the other check methods in SecurityManager is to call the SecurityManager checkPermission method to determine if the calling thread has permission to perform the requested operation.
Note that the checkPermission method with just a single permission argument always performs security checks within the context of the currently executing thread. Sometimes a security check that should be made within a given context will actually need to be done from within a different context (for example, from within a worker thread). The getSecurityContext method and the checkPermission method that includes a context argument are provided for this situation. The getSecurityContext method returns a "snapshot" of the current calling context. (The default implementation returns an AccessControlContext object.) A sample call is the following:
Object context = null; SecurityManager sm = System.getSecurityManager(); if (sm != null) context = sm.getSecurityContext();
The checkPermission method that takes a context object in addition to a permission makes access decisions based on that context, rather than on that of the current execution thread. Code within a different context can thus call that method, passing the permission and the previously-saved context object. A sample call, using the SecurityManager sm obtained as in the previous example, is the following:
if (sm != null) sm.checkPermission(permission, context);
Permissions fall into these categories: File, Socket, Net, Security, Runtime, Property, AWT, Reflect, and Serializable. The classes managing these various permission categories are java.io.FilePermission, java.net.SocketPermission, java.net.NetPermission, java.security.SecurityPermission, java.lang.RuntimePermission, java.util.PropertyPermission, java.awt.AWTPermission, java.lang.reflect.ReflectPermission, and java.io.SerializablePermission.
All but the first two (FilePermission and SocketPermission) are subclasses of java.security.BasicPermission, which itself is an abstract subclass of the top-level class for permissions, which is java.security.Permission. BasicPermission defines the functionality needed for all permissions that contain a name that follows the hierarchical property naming convention (for example, "exitVM", "setFactory", "queuePrintJob", etc). An asterisk may appear at the end of the name, following a ".", or by itself, to signify a wildcard match. For example: "a.*" or "*" is valid, "*a" or "a*b" is not valid.
FilePermission and SocketPermission are subclasses of the top-level class for permissions (java.security.Permission). Classes like these that have a more complicated name syntax than that used by BasicPermission subclass directly from Permission rather than from BasicPermission. For example, for a java.io.FilePermission object, the permission name is the path name of a file (or directory).
Some of the permission classes have an "actions" list that tells the actions that are permitted for the object. For example, for a java.io.FilePermission object, the actions list (such as "read, write") specifies which actions are granted for the specified file (or for files in the specified directory).
Other permission classes are for "named" permissions - ones that contain a name but no actions list; you either have the named permission or you don't.
Note: There is also a java.security.AllPermission permission that implies all permissions. It exists to simplify the work of system administrators who might need to perform multiple tasks that require all (or numerous) permissions.
See Permissions in the Java 2 SDK for permission-related information. This document includes, for example, a table listing the various SecurityManager check methods and the permission(s) the default implementation of each such method requires. It also contains a table of all the version 1.2 methods that require permissions, and for each such method tells which permission it requires.
For more information about SecurityManager changes made in the Java 2 SDK and advice regarding porting of 1.1-style security managers, see the security documentation .
| Field Summary | |
|---|---|
| protected boolean |
inCheck
Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead. |
| Constructor Summary | |
|---|---|
|
SecurityManager
() Constructs a new SecurityManager. |
|
| Method Summary | |
|---|---|
| void |
checkAccept
(
String
host, int port) Throws a SecurityException if the calling thread is not permitted to accept a socket connection from the specified host and port number. |
| void |
checkAccess
(
Thread
t) Throws a SecurityException if the calling thread is not allowed to modify the thread argument. |
| void |
checkAccess
(
ThreadGroup
g) Throws a SecurityException if the calling thread is not allowed to modify the thread group argument. |
| void |
checkAwtEventQueueAccess
() Throws a SecurityException if the calling thread is not allowed to access the AWT event queue. |
| void |
checkConnect
(
String
host, int port) Throws a SecurityException if the calling thread is not allowed to open a socket connection to the specified host and port number. |
| void |
checkConnect
(
String
host, int port,
Object
context) Throws a SecurityException if the specified security context is not allowed to open a socket connection to the specified host and port number. |
| void |
checkCreateClassLoader
() Throws a SecurityException if the calling thread is not allowed to create a new class loader. |
| void |
checkDelete
(
String
file) Throws a SecurityException if the calling thread is not allowed to delete the specified file. |
| void |
checkExec
(
String
cmd) Throws a SecurityException if the calling thread is not allowed to create a subprocess. |
| void |
checkExit
(int status) Throws a SecurityException if the calling thread is not allowed to cause the Java Virtual Machine to halt with the specified status code. |
| void |
checkLink
(
String
lib) Throws a SecurityException if the calling thread is not allowed to dynamic link the library code specified by the string argument file. |
| void |
checkListen
(int port) Throws a SecurityException if the calling thread is not allowed to wait for a connection request on the specified local port number. |
| void |
checkMemberAccess
(
Class
clazz, int which) Throws a SecurityException if the calling thread is not allowed to access members. |
| void |
checkMulticast
(
InetAddress
maddr) Throws a SecurityException if the calling thread is not allowed to use (join/leave/send/receive) IP multicast. |
| void |
checkMulticast
(
InetAddress
maddr, byte ttl) Deprecated. Use #checkPermission(java.security.Permission) instead |
| void |
checkPackageAccess
(
String
pkg) Throws a SecurityException if the calling thread is not allowed to access the package specified by the argument. |
| void |
checkPackageDefinition
(
String
pkg) Throws a SecurityException if the calling thread is not allowed to define classes in the package specified by the argument. |
| void |
checkPermission
(
Permission
perm) Throws a SecurityException if the requested access, specified by the given permission, is not permitted based on the security policy currently in effect. |
| void |
checkPermission
(
Permission
perm,
Object
context) Throws a SecurityException if the specified security context is denied access to the resource specified by the given permission. |
| void |
checkPrintJobAccess
() Throws a SecurityException if the calling thread is not allowed to initiate a print job request. |
| void |
checkPropertiesAccess
() Throws a SecurityException if the calling thread is not allowed to access or modify the system properties. |
| void |
checkPropertyAccess
(
String
key) Throws a SecurityException if the calling thread is not allowed to access the system property with the specified key name. |
| void |
checkRead
(java.io.FileDescriptor fd)
Throws a SecurityException if the calling thread is not allowed to read from the specified file descriptor. |
| void |
checkRead
(
String
file) Throws a SecurityException if the calling thread is not allowed to read the file specified by the string argument. |
| void |
checkRead
(
String
file,
Object
context) Throws a SecurityException if the specified security context is not allowed to read the file specified by the string argument. |
| void |
checkSecurityAccess
(
String
target) Determines whether the permission with the specified permission target name should be granted or denied. |
| void |
checkSetFactory
() Throws a SecurityException if the calling thread is not allowed to set the socket factory used by ServerSocket or Socket, or the stream handler factory used by URL. |
| void |
checkSystemClipboardAccess
() Throws a SecurityException if the calling thread is not allowed to access the system clipboard. |
| boolean |
checkTopLevelWindow
(
Object
window) Returns false if the calling thread is not trusted to bring up the top-level window indicated by the window argument. |
| void |
checkWrite
(java.io.FileDescriptor fd)
Throws a SecurityException if the calling thread is not allowed to write to the specified file descriptor. |
| void |
checkWrite
(
String
file) Throws a SecurityException if the calling thread is not allowed to write to the file specified by the string argument. |
| protected int |
classDepth
(
String
name) Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead. |
| protected int |
classLoaderDepth
() Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead. |
| protected ClassLoader |
currentClassLoader
() Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead. |
| protected Class |
currentLoadedClass
() Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead. |
| protected Class [] |
getClassContext
() Returns the current execution stack as an array of classes. |
| boolean |
getInCheck
() Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead. |
| Object |
getSecurityContext
() Creates an object that encapsulates the current execution environment. |
| ThreadGroup |
getThreadGroup
() Returns the thread group into which to instantiate any new thread being created at the time this is being called. |
| protected boolean |
inClass
(
String
name) Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead. |
| protected boolean |
inClassLoader
() Deprecated. This type of security checking is not recommended. It is recommended that the checkPermission call be used instead. |
| Methods inherited from class java.lang. Object |
|---|
| clone , equals , finalize , getClass , hashCode , notify , notifyAll , toString , wait , wait , wait |
| Field Detail |
|---|
protected boolean inCheck
| Constructor Detail |
|---|
public SecurityManager()
If there is a security manager already installed, this method first calls the security manager's checkPermission method with the RuntimePermission("createSecurityManager") permission to ensure the calling thread has permission to create a new security manager. This may result in throwing a SecurityException.
| Method Detail |
|---|
public boolean getInCheck()
protected Class[] getClassContext()
The length of the array is the number of methods on the execution stack. The element at index 0 is the class of the currently executing method, the element at index 1 is the class of that method's caller, and so on.
protected ClassLoader currentClassLoader()
This method will return null in the following three cases:
protected Class currentLoadedClass()
This method will return null in the following three cases:
protected int classDepth(String name)
protected int classLoaderDepth()
This method will return -1 in the following three cases:
protected boolean inClass(String name)
protected boolean inClassLoader()
public Object getSecurityContext()
The default implementation of this method is to return an AccessControlContext object.
public void checkPermission(Permission perm)
This method calls AccessController.checkPermission with the given permission.
public void checkPermission(Permission perm,
Object context)
If context is an instance of AccessControlContext then the AccessControlContext.checkPermission method is invoked with the specified permission.
If context is not an instance of AccessControlContext then a SecurityException is thrown.
public void checkCreateClassLoader()
This method calls checkPermission with the RuntimePermission("createClassLoader") permission.
If you override this method, then you should make a call to super.checkCreateClassLoader at the point the overridden method would normally throw an exception.
public void checkAccess(Thread t)
This method is invoked for the current security manager by the stop, suspend, resume, setPriority, setName, and setDaemon methods of class Thread.
If the thread argument is a system thread (belongs to the thread group with a null parent) then this method calls checkPermission with the RuntimePermission("modifyThread") permission. If the thread argument is not a system thread, this method just returns silently.
Applications that want a stricter policy should override this method. If this method is overridden, the method that overrides it should additionally check to see if the calling thread has the RuntimePermission("modifyThread") permission, and if so, return silently. This is to ensure that code granted that permission (such as the SDK itself) is allowed to manipulate any thread.
If this method is overridden, then super.checkAccess should be called by the first statement in the overridden method, or the equivalent security check should be placed in the overridden method.
public void checkAccess(ThreadGroup g)
This method is invoked for the current security manager when a new child thread or child thread group is created, and by the setDaemon, setMaxPriority, stop, suspend, resume, and destroy methods of class ThreadGroup.
If the thread group argument is the system thread group ( has a null parent) then this method calls checkPermission with the RuntimePermission("modifyThreadGroup") permission. If the thread group argument is not the system thread group, this method just returns silently.
Applications that want a stricter policy should override this method. If this method is overridden, the method that overrides it should additionally check to see if the calling thread has the RuntimePermission("modifyThreadGroup") permission, and if so, return silently. This is to ensure that code granted that permission (such as the SDK itself) is allowed to manipulate any thread.
If this method is overridden, then super.checkAccess should be called by the first statement in the overridden method, or the equivalent security check should be placed in the overridden method.
public void checkExit(int status)
This method is invoked for the current security manager by the exit method of class Runtime. A status of 0 indicates success; other values indicate various errors.
This method calls checkPermission with the RuntimePermission("exitVM") permission.
If you override this method, then you should make a call to super.checkExit at the point the overridden method would normally throw an exception.
public void checkExec(String cmd)
This method is invoked for the current security manager by the exec methods of class Runtime.
This method calls checkPermission with the FilePermission(cmd,"execute") permission if cmd is an absolute path, otherwise it calls checkPermission with FilePermission("<<ALL FILES>>","execute").
If you override this method, then you should make a call to super.checkExec at the point the overridden method would normally throw an exception.
public void checkLink(String lib)
This method is invoked for the current security manager by methods load and loadLibrary of class Runtime.
This method calls checkPermission with the RuntimePermission("loadLibrary."+lib) permission.
If you override this method, then you should make a call to super.checkLink at the point the overridden method would normally throw an exception.
public void checkRead(FileDescriptorfd)
This method calls checkPermission with the RuntimePermission("readFileDescriptor") permission.
If you override this method, then you should make a call to super.checkRead at the point the overridden method would normally throw an exception.
FileDescriptor,
checkPermission
public void checkRead(String file)
This method calls checkPermission with the FilePermission(file,"read") permission.
If you override this method, then you should make a call to super.checkRead at the point the overridden method would normally throw an exception.
public void checkRead(String file,
Object context)
If context is an instance of AccessControlContext then the AccessControlContext.checkPermission method will be invoked with the FilePermission(file,"read") permission.
If context is not an instance of AccessControlContext then a SecurityException is thrown.
If you override this method, then you should make a call to super.checkRead at the point the overridden method would normally throw an exception.
public void checkWrite(FileDescriptorfd)
This method calls checkPermission with the RuntimePermission("writeFileDescriptor") permission.
If you override this method, then you should make a call to super.checkWrite at the point the overridden method would normally throw an exception.
FileDescriptor,
checkPermission
public void checkWrite(String file)
This method calls checkPermission with the FilePermission(file,"write") permission.
If you override this method, then you should make a call to super.checkWrite at the point the overridden method would normally throw an exception.
public void checkDelete(String file)
This method is invoked for the current security manager by the delete method of class File.
This method calls checkPermission with the FilePermission(file,"delete") permission.
If you override this method, then you should make a call to super.checkDelete at the point the overridden method would normally throw an exception.
public void checkConnect(String host,
int port)
A port number of -1 indicates that the calling method is attempting to determine the IP address of the specified host name.
This method calls checkPermission with the SocketPermission(host+":"+port,"connect") permission if the port is not equal to -1. If the port is equal to -1, then it calls checkPermission with the SocketPermission(host,"resolve") permission.
If you override this method, then you should make a call to super.checkConnect at the point the overridden method would normally throw an exception.
public void checkConnect(String host,
int port,
Object context)
A port number of -1 indicates that the calling method is attempting to determine the IP address of the specified host name.
If context is not an instance of AccessControlContext then a SecurityException is thrown.
Otherwise, the port number is checked. If it is not equal to -1, the context's checkPermission method is called with a SocketPermission(host+":"+port,"connect") permission. If the port is equal to -1, then the context's checkPermission method is called with a SocketPermission(host,"resolve") permission.
If you override this method, then you should make a call to super.checkConnect at the point the overridden method would normally throw an exception.
public void checkListen(int port)
If port is not 0, this method calls checkPermission with the SocketPermission("localhost:"+port,"listen"). If port is zero, this method calls checkPermission with SocketPermission("localhost:1024-","listen").
If you override this method, then you should make a call to super.checkListen at the point the overridden method would normally throw an exception.
public void checkAccept(String host,
int port)
This method is invoked for the current security manager by the accept method of class ServerSocket.
This method calls checkPermission with the SocketPermission(host+":"+port,"accept") permission.
If you override this method, then you should make a call to super.checkAccept at the point the overridden method would normally throw an exception.
public void checkMulticast(InetAddress maddr)
This method calls checkPermission with the java.net.SocketPermission(maddr.getHostAddress(), "accept,connect") permission.
If you override this method, then you should make a call to super.checkMulticast at the point the overridden method would normally throw an exception.
public void checkMulticast(InetAddress maddr,
byte ttl)
This method calls checkPermission with the java.net.SocketPermission(maddr.getHostAddress(), "accept,connect") permission.
If you override this method, then you should make a call to super.checkMulticast at the point the overridden method would normally throw an exception.
public void checkPropertiesAccess()
This method is used by the getProperties and setProperties methods of class System.
This method calls checkPermission with the PropertyPermission("*", "read,write") permission.
If you override this method, then you should make a call to super.checkPropertiesAccess at the point the overridden method would normally throw an exception.
public void checkPropertyAccess(String key)
This method is used by the getProperty method of class System.
This method calls checkPermission with the PropertyPermission(key, "read") permission.
If you override this method, then you should make a call to super.checkPropertyAccess at the point the overridden method would normally throw an exception.
public boolean checkTopLevelWindow(Object window)
See class Window for more information on trusted and untrusted windows.
This method calls checkPermission with the AWTPermission("showWindowWithoutWarningBanner") permission, and returns true if a SecurityException is not thrown, otherwise it returns false.
If you override this method, then you should make a call to super.checkTopLevelWindow at the point the overridden method would normally return false, and the value of super.checkTopLevelWindow should be returned.
public void checkPrintJobAccess()
This method calls checkPermission with the RuntimePermission("queuePrintJob") permission.
If you override this method, then you should make a call to super.checkPrintJobAccess at the point the overridden method would normally throw an exception.
public void checkSystemClipboardAccess()
This method calls checkPermission with the AWTPermission("accessClipboard") permission.
If you override this method, then you should make a call to super.checkSystemClipboardAccess at the point the overridden method would normally throw an exception.
public void checkAwtEventQueueAccess()
This method calls checkPermission with the AWTPermission("accessEventQueue") permission.
If you override this method, then you should make a call to super.checkAwtEventQueueAccess at the point the overridden method would normally throw an exception.
public void checkPackageAccess(String pkg)
This method is used by the loadClass method of class loaders.
This method first gets a list of restricted packages by obtaining a comma-separated list from a call to java.security.Security.getProperty("package.access"), and checks to see if pkg starts with or equals any of the restricted packages. If it does, then checkPermission gets called with the RuntimePermission("accessClassInPackage."+pkg) permission.
If this method is overridden, then super.checkPackageAccess should be called as the first line in the overridden method.
public void checkPackageDefinition(String pkg)
This method is used by the loadClass method of some class loaders.
This method first gets a list of restricted packages by obtaining a comma-separated list from a call to java.security.Security.getProperty("package.definition"), and checks to see if pkg starts with or equals any of the restricted packages. If it does, then checkPermission gets called with the RuntimePermission("defineClassInPackage."+pkg) permission.
If this method is overridden, then super.checkPackageDefinition should be called as the first line in the overridden method.
public void checkSetFactory()
This method calls checkPermission with the RuntimePermission("setFactory") permission.
If you override this method, then you should make a call to super.checkSetFactory at the point the overridden method would normally throw an exception.
public void checkMemberAccess(Class clazz,
int which)
The default policy is to allow access to PUBLIC members, as well as access to classes that have the same class loader as the caller. In all other cases, this method calls checkPermission with the RuntimePermission("accessDeclaredMembers") permission.
If this method is overridden, then a call to super.checkMemberAccess cannot be made, as the default implementation of checkMemberAccess relies on the code being checked being at a stack depth of 4.
public void checkSecurityAccess(String target)
If the requested permission is allowed, this method returns quietly. If denied, a SecurityException is raised.
This method creates a SecurityPermission object for the given permission target name and calls checkPermission with it.
See the documentation for SecurityPermission for a list of possible permission target names.
If you override this method, then you should make a call to super.checkSecurityAccess at the point the overridden method would normally throw an exception.
public ThreadGroup getThreadGroup()