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Class java.lang.SecurityManager

java.lang.Object | +----java.lang.SecurityManager
public abstract class SecurityManager
extends Object
The security manager is an abstract 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 the operation is being performed by a class created via a class loader rather than installed locally. Classes loaded via a class loader (especially if they have been downloaded over a network) may be less trustworthy than classes from files installed locally. 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 default implementation of each of the checkXXX methods is to assume that the caller does not have permission to perform the requested operation.

See Also:
ClassLoader, SecurityException, checkTopLevelWindow, getSecurityManager, setSecurityManager

Variable Index

o inCheck
This field is true if there is a security check in progress; false otherwise.

Constructor Index

o SecurityManager()
Constructs a new SecurityManager.

Method Index

o checkAccept(String, int)
Throws a SecurityException if the calling thread is not permitted to accept a socket connection from the specified host and port number.
o checkAccess(Thread)
Throws a SecurityException if the calling thread is not allowed to modify the thread argument.
o checkAccess(ThreadGroup)
Throws a SecurityException if the calling thread is not allowed to modify the thread group argument.
o checkAwtEventQueueAccess()
Tests if a client can get access to the AWT event queue.
o checkConnect(String, int)
Throws a SecurityException if the calling thread is not allowed to open a socket connection to the specified host and port number.
o checkConnect(String, int, Object)
Throws a SecurityException if the specified security context is not allowed to open a socket connection to the specified host and port number.
o checkCreateClassLoader()
Throws a SecurityException if the calling thread is not allowed to create a new class loader.
o checkDelete(String)
Throws a SecurityException if the calling thread is not allowed to delete the specified file.
o checkExec(String)
Throws a SecurityException if the calling thread is not allowed to create a subprocss.
o checkExit(int)
Throws a SecurityException if the calling thread is not allowed to cause the Java Virtual Machine to halt with the specified status code.
o checkLink(String)
Throws a SecurityException if the calling thread is not allowed to dynamic link the library code specified by the string argument file.
o checkListen(int)
Throws a SecurityException if the calling thread is not allowed to wait for a connection request on the specified local port number.
o checkMemberAccess(Class, int)
Tests if a client is allowed to access members.
o checkMulticast(InetAddress)
Tests if current execution context is allowed to use (join/leave/send/receive) IP multicast.
o checkMulticast(InetAddress, byte)
Tests to see if current execution context is allowed to use (join/leave/send/receive) IP multicast.
o checkPackageAccess(String)
Throws a SecurityException if the calling thread is not allowed to access the package specified by the argument.
o checkPackageDefinition(String)
Throws a SecurityException if the calling thread is not allowed to define classes in the package specified by the argument.
o checkPrintJobAccess()
Tests if a client can initiate a print job request.
o checkPropertiesAccess()
Throws a SecurityException if the calling thread is not allowed to access or modify the system properties.
o checkPropertyAccess(String)
Throws a SecurityException if the calling thread is not allowed to access the system property with the specified key name.
o checkRead(FileDescriptor)
Throws a SecurityException if the calling thread is not allowed to read from the specified file descriptor.
o checkRead(String)
Throws a SecurityException if the calling thread is not allowed to read the file specified by the string argument.
o checkRead(String, Object)
Throws a SecurityException if the specified security context is not allowed to read the file specified by the string argument.
o checkSecurityAccess(String)
Tests access to certain operations for a security API action.
o 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.
o checkSystemClipboardAccess()
Tests if a client can get access to the system clipboard.
o checkTopLevelWindow(Object)
Returns false if the calling thread is not trusted to bring up the top-level window indicated by the window argument.
o checkWrite(FileDescriptor)
Throws a SecurityException if the calling thread is not allowed to write to the specified file descriptor.
o checkWrite(String)
Throws a SecurityException if the calling thread is not allowed to write to the file specified by the string argument.
o classDepth(String)
Returns the stack depth of the specified class.
o classLoaderDepth()
Returns the stack depth of the most recently executing method from a class defined using a class loader.
o currentClassLoader()
Returns an object describing the most recent class loader executing on the stack.
o currentLoadedClass()
Returns the current Class with a ClassLoader on the execution stack.
o getClassContext()
Returns the current execution stack as an array of classes.
o getInCheck()
Tests if there is a security check in progress.
o getSecurityContext()
Creates an object that encapsulates the current execution environment.
o getThreadGroup()
Returns the thread group into which to instantiate any new thread being created at the time this is being called.
o inClass(String)
Tests if the specified String is in this Class.
o inClassLoader()
Tests if the current ClassLoader is equal to null.

Variables

o inCheck protected boolean inCheck
This field is true if there is a security check in progress; false otherwise.

Constructors

o SecurityManager protected SecurityManager()
Constructs a new SecurityManager. An application is not allowed to create a new security manager if there is already a current security manager.

Throws: SecurityException
if a security manager already exists.
See Also:
getSecurityManager

Methods

o getInCheck public boolean getInCheck()
Tests if there is a security check in progress.

Returns:
the value of the inCheck field. This field should contain true if a security check is in progress; false otherwise.
See Also:
inCheck
o getClassContext protected native Class[] getClassContext()
Returns the current execution stack as an array of classes.

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.

Returns:
the execution stack.
o currentClassLoader protected native ClassLoader currentClassLoader()
Returns an object describing the most recent class loader executing on the stack.

Returns:
the class loader of the most recent occurrence on the stack of a method from a class defined using a class loader; returns null if there is no occurrence on the stack of a method from a class defined using a class loader.
o currentLoadedClass protected Class currentLoadedClass()
Returns the current Class with a ClassLoader on the execution stack.

o classDepth protected native int classDepth(String name)
Returns the stack depth of the specified class.

Parameters:
name - the fully qualified name of the class to search for.
Returns:
the depth on the stack frame of the first occurrence of a method from a class with the specified name; -1 if such a frame cannot be found.
o classLoaderDepth protected native int classLoaderDepth()
Returns the stack depth of the most recently executing method from a class defined using a class loader.

Returns:
the depth on the stack frame of the most recent occurrence of a method from a class defined using a class loader; returns -1 if there is no occurrence of a method from a class defined using a class loader.
o inClass protected boolean inClass(String name)
Tests if the specified String is in this Class.

Parameters:
name - the fully qualified name of the class.
Returns:
true if a method from a class with the specified name is on the execution stack; false otherwise.
o inClassLoader protected boolean inClassLoader()
Tests if the current ClassLoader is equal to null.

Returns:
true if a method from a class defined using a class loader is on the execution stack.
o getSecurityContext public Object getSecurityContext()
Creates an object that encapsulates the current execution environment. The result of this method is used by the three-argument checkConnect method and by the two-argument checkRead method.

These methods are needed because a trusted method may be called on to read a file or open a socket on behalf of another method. The trusted method needs to determine if the other (possibly untrusted) method would be allowed to perform the operation on its own.

Returns:
an implementation-dependent object that encapsulates sufficient information about the current execution environment to perform some security checks later.
See Also:
checkConnect, checkRead
o checkCreateClassLoader public void checkCreateClassLoader()
Throws a SecurityException if the calling thread is not allowed to create a new class loader.

The checkCreateClassLoader method for class SecurityManager always throws a SecurityException.

Throws: SecurityException
if the caller does not have permission to create a new class loader.
See Also:
ClassLoader
o checkAccess public void checkAccess(Thread g)
Throws a SecurityException if the calling thread is not allowed to modify the thread argument.

This method is invoked for the current security manager by the stop, suspend, resume, setPriority, setName, and setDaemon methods of class Thread.

The checkAccess method for class SecurityManager always throws a SecurityException.

Parameters:
g - the thread to be checked.
Throws: SecurityException
if the caller does not have permission to modify the thread.
See Also:
getSecurityManager, resume, setDaemon, setName, setPriority, stop, suspend
o checkAccess public void checkAccess(ThreadGroup g)
Throws a SecurityException if the calling thread is not allowed to modify the thread group argument.

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.

The checkAccess method for class SecurityManager always throws a SecurityException.

Parameters:
g - the thread group to be checked.
Throws: SecurityException
if the caller does not have permission to modify the thread group.
See Also:
getSecurityManager, destroy, resume, setDaemon, setMaxPriority, stop, suspend
o checkExit public 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.

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.

The checkExit method for class SecurityManager always throws a SecurityException.

Parameters:
status - the exit status.
Throws: SecurityException
if the caller does not have permission to halt the Java Virtual Machine with the specified status.
See Also:
exit, getSecurityManager
o checkExec public void checkExec(String cmd)
Throws a SecurityException if the calling thread is not allowed to create a subprocss.

This method is invoked for the current security manager by the exec methods of class Runtime.

The checkExec method for class SecurityManager always throws a SecurityException.

Parameters:
cmd - the specified system command.
Throws: SecurityException
if the caller does not have permission to create a subprocess.
See Also:
exec, exec, exec, exec, getSecurityManager
o checkLink public 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. The argument is either a simple library name or a complete filename.

This method is invoked for the current security manager by methods load and loadLibrary of class Runtime.

The checkLink method for class SecurityManager always throws a SecurityException.

Parameters:
lib - the name of the library.
Throws: SecurityException
if the caller does not have permission to dynamically link the library.
See Also:
load, loadLibrary, getSecurityManager
o checkRead public void checkRead(FileDescriptor fd)
Throws a SecurityException if the calling thread is not allowed to read from the specified file descriptor.

The checkRead method for class SecurityManager always throws a SecurityException.

Parameters:
fd - the system-dependent file descriptor.
Throws: SecurityException
if the caller does not have permission to access the specified file descriptor.
See Also:
FileDescriptor
o checkRead public void checkRead(String file)
Throws a SecurityException if the calling thread is not allowed to read the file specified by the string argument.

The checkRead method for class SecurityManager always throws a SecurityException.

Parameters:
file - the system-dependent file name.
Throws: SecurityException
if the caller does not have permission to access the specified file.
o checkRead public 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. The context must be a security context returned by a previous call to getSecurityContext.

The checkRead method for class SecurityManager always throws a SecurityException.

Parameters:
file - the system-dependent filename.
context - a system-dependent security context.
Throws: SecurityException
if the specified security context does not have permission to read the specified file.
See Also:
getSecurityContext
o checkWrite public void checkWrite(FileDescriptor fd)
Throws a SecurityException if the calling thread is not allowed to write to the specified file descriptor.

The checkWrite method for class SecurityManager always throws a SecurityException.

Parameters:
fd - the system-dependent file descriptor.
Throws: SecurityException
if the caller does not have permission to access the specified file descriptor.
See Also:
FileDescriptor
o checkWrite public void checkWrite(String file)
Throws a SecurityException if the calling thread is not allowed to write to the file specified by the string argument.

The checkWrite method for class SecurityManager always throws a SecurityException.

Parameters:
file - the system-dependent filename.
Throws: SecurityException
if the caller does not have permission to access the specified file.
o checkDelete public void checkDelete(String file)
Throws a SecurityException if the calling thread is not allowed to delete the specified file.

This method is invoked for the current security manager by the delete method of class File.

The checkDelete method for class SecurityManager always throws a SecurityException.

Parameters:
file - the system-dependent filename.
Throws: SecurityException
if the caller does not have permission to delete the file.
See Also:
delete, getSecurityManager
o checkConnect public 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.

A port number of -1 indicates that the calling method is attempting to determine the IP address of the specified host name.

The checkConnect method for class SecurityManager always throws a SecurityException.

Parameters:
host - the host name port to connect to.
port - the protocol port to connect to.
Throws: SecurityException
if the caller does not have permission to open a socket connection to the specified host and port.
o checkConnect public 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.

A port number of -1 indicates that the calling method is attempting to determine the IP address of the specified host name.

The checkConnect method for class SecurityManager always throws a SecurityException.

Parameters:
host - the host name port to connect to.
port - the protocol port to connect to.
context - a system-dependent security context.
Throws: SecurityException
if the specified security context does not have permission to open a socket connection to the specified host and port.
See Also:
getSecurityContext
o checkListen public 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.

The checkListen method for class SecurityManager always throws a SecurityException.

Parameters:
port - the local port.
Throws: SecurityException
if the caller does not have permission to listen on the specified port.
o checkAccept public 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.

This method is invoked for the current security manager by the accept method of class ServerSocket.

The checkAccept method for class SecurityManager always throws a SecurityException.

Parameters:
host - the host name of the socket connection.
port - the port number of the socket connection.
Throws: SecurityException
if the caller does not have permission to accept the connection.
See Also:
getSecurityManager, accept
o checkMulticast public void checkMulticast(InetAddress maddr)
Tests if current execution context is allowed to use (join/leave/send/receive) IP multicast.

Parameters:
multicast - Internet group address to be used.
Throws: SecurityException
if a security error has occurred.
o checkMulticast public void checkMulticast(InetAddress maddr, byte ttl)
Tests to see if current execution context is allowed to use (join/leave/send/receive) IP multicast.

Parameters:
multicast - Internet group address to be used.
ttl - value in use, if it is multicast send.
Throws: SecurityException
if a security error has occurred.
o checkPropertiesAccess public void checkPropertiesAccess()
Throws a SecurityException if the calling thread is not allowed to access or modify the system properties.

This method is used by the getProperties and setProperties methods of class System.

The checkPropertiesAccess method for class SecurityManager always throws a SecurityException.

Throws: SecurityException
if the caller does not have permission to access or modify the system properties.
See Also:
getProperties, setProperties
o checkPropertyAccess public void checkPropertyAccess(String key)
Throws a SecurityException if the calling thread is not allowed to access the system property with the specified key name.

This method is used by the getProperty method of class System.

The checkPropertiesAccess method for class SecurityManager always throws a SecurityException.

Parameters:
key - a system property key.
Throws: SecurityException
if the caller does not have permission to access the specified system property.
See Also:
getProperty
o checkTopLevelWindow public 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. In this case, the caller can still decide to show the window, but the window should include some sort of visual warning. If the method returns true, then the window can be shown without any special restrictions.

See class Window for more information on trusted and untrusted windows.

The checkSetFactory method for class SecurityManager always returns false.

Parameters:
window - the new window that is being created.
Returns:
true if the caller is trusted to put up top-level windows; false otherwise.
Throws: SecurityException
if creation is disallowed entirely.
See Also:
Window
o checkPrintJobAccess public void checkPrintJobAccess()
Tests if a client can initiate a print job request.

o checkSystemClipboardAccess public void checkSystemClipboardAccess()
Tests if a client can get access to the system clipboard.

o checkAwtEventQueueAccess public void checkAwtEventQueueAccess()
Tests if a client can get access to the AWT event queue.

o checkPackageAccess public void checkPackageAccess(String pkg)
Throws a SecurityException if the calling thread is not allowed to access the package specified by the argument.

This method is used by the loadClass method of class loaders.

The checkPackageAccess method for class SecurityManager always throws a SecurityException.

Parameters:
pkg - the package name.
Throws: SecurityException
if the caller does not have permission to access the specified package.
See Also:
loadClass
o checkPackageDefinition public void checkPackageDefinition(String pkg)
Throws a SecurityException if the calling thread is not allowed to define classes in the package specified by the argument.

This method is used by the loadClass method of some class loaders.

The checkPackageDefinition method for class SecurityManager always throws a SecurityException.

Parameters:
pkg - the package name.
Throws: SecurityException
if the caller does not have permission to define classes in the specified package.
See Also:
loadClass
o checkSetFactory public 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.

The checkSetFactory method for class SecurityManager always throws a SecurityException.

Throws: SecurityException
if the caller does not have permission to specify a socket factory or a stream handler factory.
See Also:
setSocketFactory, setSocketImplFactory, setURLStreamHandlerFactory
o checkMemberAccess public void checkMemberAccess(Class clazz, int which)
Tests if a client is allowed to access members. If access is denied, throw a SecurityException. The default policy is to deny all accesses.

o checkSecurityAccess public void checkSecurityAccess(String action)
Tests access to certain operations for a security API action.

o getThreadGroup public ThreadGroup getThreadGroup()
Returns the thread group into which to instantiate any new thread being created at the time this is being called. By default, it returns the thread group of the current thread. This should be overriden by specific security manager to return the appropriate thread group.

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