java.lang
Class SecurityManager

java.lang.Object
  java.lang.SecurityManager

Direct Known Subclasses:

mSecurityManager

public abstract class SecurityManager

extends Object

SecurityManager is a class you can extend to create your own Java security policy. By default, there is no SecurityManager installed, which means that all things are permitted to all people. The security manager, if set, is consulted before doing anything with potentially dangerous results, and throws a SecurityException if the action is forbidden.

A typical check is as follows, just before the dangerous operation:

 SecurityManager sm = System.getSecurityManager();
 if (sm != null)
   sm.checkABC(argument, ...);
 

Note that this is thread-safe, by caching the security manager in a local variable rather than risking a NullPointerException if the mangager is changed between the check for null and before the permission check.

Field Summary

protected boolean

inCheck Tells whether or not the SecurityManager is currently performing a security check.

Constructor Summary

protected

SecurityManager() Construct a new security manager.

Method Summary

void	checkAccept(String host, int port) Check if the current thread is allowed to accept a connection from a particular host on a particular port.
void	checkAccess(Thread t) Check if the current thread is allowed to modify another Thread.
void	checkAccess(ThreadGroup g) Check if the current thread is allowed to modify a ThreadGroup.
void	checkConnect(String host, int port) Check if the current thread is allowed to connect to a given host on a given port.
void	checkConnect(String host, int port, Object securityContext) Check if the current thread is allowed to connect to a given host on a given port, using the given security context.
void	checkCreateClassLoader() Check if the current thread is allowed to create a ClassLoader.
void	checkDelete(String filename) Check if the current thread is allowed to delete the given file.
void	checkExec(String program) Check if the current thread is allowed to execute the given program.
void	checkExit(int status) Check if the current thread is allowed to exit the JVM with the given status.
void	checkLink(String filename) Check if the current thread is allowed to link in the given native library.
void	checkListen(int port) Check if the current thread is allowed to listen to a specific port for data.
void	checkMemberAccess(Class c, int memberType) Check if the current thread is allowed to get certain types of Methods, Fields and Constructors from a Class object.
void	checkPackageAccess(String packageName) Check if the current thread is allowed to access the specified package at all.
void	checkPackageDefinition(String packageName) Check if the current thread is allowed to define a class into the specified package.
void	checkPrintJobAccess() Check if the current thread is allowed to create a print job.
void	checkPropertiesAccess() Check if the current thread is allowed to read or write all the system properties at once.
void	checkPropertyAccess(String key) Check if the current thread is allowed to read a particular system property (writes are checked directly via checkPermission).
void	checkRead(String filename) Check if the current thread is allowed to read the given file.
void	checkRead(String filename, Object context) Check if the current thread is allowed to read the given file.
void	checkSecurityAccess(String action) Test whether a particular security action may be taken.
void	checkSetFactory() Check if the current thread is allowed to set the current socket factory.
void	checkSystemClipboardAccess() Check if the current thread is allowed to use the system clipboard.
boolean	checkTopLevelWindow(Object window) Check if the current thread is allowed to create a top-level window.
void	checkWrite(String filename) Check if the current thread is allowed to write the given file.
protected int	classDepth(String className) Get the depth of a particular class on the execution stack.
protected int	classLoaderDepth() Deprecated. use #checkPermission(Permission) instead
protected ClassLoader	currentClassLoader() Find the ClassLoader of the first non-system class on the execution stack.
protected Class	currentLoadedClass() Find the first non-system class on the execution stack.
protected Class[]	getClassContext() Get a list of all the classes currently executing methods on the Java stack.
boolean	getInCheck() Tells whether or not the SecurityManager is currently performing a security check.
Object	getSecurityContext() Get an implementation-dependent Object that contains enough information about the current environment to be able to perform standard security checks later.
protected boolean	inClass(String className) Tell whether the specified class is on the execution stack.
protected boolean	inClassLoader() Deprecated. use #checkPermission(Permission) instead

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, toString

Field Detail

inCheck

protected boolean inCheck

Tells whether or not the SecurityManager is currently performing a security check.

Constructor Detail

SecurityManager

protected SecurityManager()

Construct a new security manager.

Throws:

SecurityException - if permission is denied

Method Detail

getInCheck

public boolean getInCheck()

Tells whether or not the SecurityManager is currently performing a security check.

Returns:

true if the SecurityManager is in a security check

See Also:

inCheck

getClassContext

protected final Class[] getClassContext()

Get a list of all the classes currently executing methods on the Java stack. getClassContext()[0] is the currently executing method (ie. the class that CALLED getClassContext, not SecurityManager).

Returns:

an array of classes on the Java execution stack

currentClassLoader

protected ClassLoader currentClassLoader()

Find the ClassLoader of the first non-system class on the execution stack.

Returns:

the most recent non-system ClassLoader on the execution stack

currentLoadedClass

protected Class currentLoadedClass()

Find the first non-system class on the execution stack. A non-system class is one whose ClassLoader is not equal to ClassLoader#getSystemClassLoader() or its ancestors.

Returns:

the most recent non-system Class on the execution stack

classDepth

protected int classDepth(String className)

Get the depth of a particular class on the execution stack.

Parameters:

className - the fully-qualified name to search for

Returns:

the index of the class on the stack, or -1

classLoaderDepth

protected int classLoaderDepth()

Deprecated. use #checkPermission(Permission) instead

Get the depth on the execution stack of the most recent non-system class. A non-system class is one whose ClassLoader is not equal to ClassLoader#getSystemClassLoader() or its ancestors. This will return -1 in three cases:

All methods on the stack are from system classes

All methods on the stack up to the first "privileged" caller, as created by AccessController.doPrivileged(PrivilegedAction), are from system classes

A check of java.security.AllPermission succeeds.

Returns:

the index of the most recent non-system Class on the stack

inClass

protected boolean inClass(String className)

Tell whether the specified class is on the execution stack.

Parameters:

className - the fully-qualified name of the class to find

Returns:

whether the specified class is on the execution stack

inClassLoader

protected boolean inClassLoader()

Deprecated. use #checkPermission(Permission) instead

Tell whether there is a class loaded with an explicit ClassLoader on the stack.

Returns:

whether a class with an explicit ClassLoader is on the stack

getSecurityContext

public Object getSecurityContext()

Get an implementation-dependent Object that contains enough information about the current environment to be able to perform standard security checks later. This is used by trusted methods that need to verify that their callers have sufficient access to perform certain operations.

Currently the only methods that use this are checkRead() and checkConnect(). The default implementation returns an AccessControlContext.

Returns:

a security context

See Also:

checkConnect(String, int, Object), checkRead(String, Object), AccessControlContext, AccessController#getContext()

checkCreateClassLoader

public void checkCreateClassLoader()

Check if the current thread is allowed to create a ClassLoader. This method is called from ClassLoader.ClassLoader(), and checks RuntimePermission("createClassLoader"). If you override this, you should call super.checkCreateClassLoader() rather than throwing an exception.

Throws:

SecurityException - if permission is denied

See Also:

ClassLoader.ClassLoader()

checkAccess

public void checkAccess(Thread t)

Check if the current thread is allowed to modify another Thread. This is called by Thread.stop(), suspend(), resume(), interrupt(), destroy(), setPriority(), setName(), and setDaemon(). The default implementation checks RuntimePermission("modifyThread") on system threads (ie. threads in ThreadGroup with a null parent), and returns silently on other threads.

If you override this, you must do two things. First, call super.checkAccess(t), to make sure you are not relaxing requirements. Second, if the calling thread has RuntimePermission("modifyThread"), return silently, so that core classes (the Classpath library!) can modify any thread.

Parameters:

t - the other Thread to check

Throws:

SecurityException - if permission is denied

NullPointerException - if t is null

See Also:

Thread#stop(), Thread#suspend(), Thread#resume(), Thread#setPriority(int), Thread#setName(String), Thread#setDaemon(boolean)

checkAccess

public void checkAccess(ThreadGroup g)

Check if the current thread is allowed to modify a ThreadGroup. This is called by Thread.Thread() (to add a thread to the ThreadGroup), ThreadGroup.ThreadGroup() (to add this ThreadGroup to a parent), ThreadGroup.stop(), suspend(), resume(), interrupt(), destroy(), setDaemon(), and setMaxPriority(). The default implementation checks RuntimePermission("modifyThread") on the system group (ie. the one with a null parent), and returns silently on other groups.

If you override this, you must do two things. First, call super.checkAccess(t), to make sure you are not relaxing requirements. Second, if the calling thread has RuntimePermission("modifyThreadGroup"), return silently, so that core classes (the Classpath library!) can modify any thread.

Parameters:

g - the ThreadGroup to check

Throws:

SecurityException - if permission is denied

NullPointerException - if g is null

See Also:

Thread#Thread(), ThreadGroup#ThreadGroup(), ThreadGroup#stop(), ThreadGroup#suspend(), ThreadGroup#resume(), ThreadGroup#interrupt(), ThreadGroup#setDaemon(boolean), ThreadGroup#setMaxPriority(int)

checkExit

public void checkExit(int status)

Check if the current thread is allowed to exit the JVM with the given status. This method is called from Runtime.exit() and Runtime.halt(). The default implementation checks RuntimePermission("exitVM"). If you override this, call super.checkExit rather than throwing an exception.

Parameters:

status - the status to exit with

Throws:

SecurityException - if permission is denied

See Also:

Runtime.exit(int), Runtime.halt(int)

checkExec

public void checkExec(String program)

Check if the current thread is allowed to execute the given program. This method is called from Runtime.exec(). If the name is an absolute path, the default implementation checks FilePermission(program, "execute"), otherwise it checks FilePermission("<<ALL FILES>>", "execute"). If you override this, call super.checkExec rather than throwing an exception.

Parameters:

program - the name of the program to exec

Throws:

SecurityException - if permission is denied

NullPointerException - if program is null

See Also:

Runtime.exec(String[], String[], File)

checkLink

public void checkLink(String filename)

Check if the current thread is allowed to link in the given native library. This method is called from Runtime.load() (and hence, by loadLibrary() as well). The default implementation checks RuntimePermission("loadLibrary." + filename). If you override this, call super.checkLink rather than throwing an exception.

Parameters:

filename - the full name of the library to load

Throws:

SecurityException - if permission is denied

NullPointerException - if filename is null

See Also:

Runtime.load(String)

checkRead

public void checkRead(String filename)

Check if the current thread is allowed to read the given file. This method is called from FileInputStream.FileInputStream(), RandomAccessFile.RandomAccessFile(), File.exists(), canRead(), isFile(), isDirectory(), lastModified(), length() and list(). The default implementation checks FilePermission(filename, "read"). If you override this, call super.checkRead rather than throwing an exception.

Parameters:

filename - the full name of the file to access

Throws:

SecurityException - if permission is denied

NullPointerException - if filename is null

See Also:

File, FileInputStream#FileInputStream(String), RandomAccessFile#RandomAccessFile(String)

checkRead

public void checkRead(String filename,
                      Object context)

Check if the current thread is allowed to read the given file. using the given security context. The context must be a result of a previous call to getSecurityContext(). The default implementation checks AccessControlContext.checkPermission(new FilePermission(filename, "read")). If you override this, call super.checkRead rather than throwing an exception.

Parameters:

filename - the full name of the file to access

context - the context to determine access for

Throws:

SecurityException - if permission is denied, or if context is not an AccessControlContext

NullPointerException - if filename is null

See Also:

getSecurityContext(), AccessControlContext#checkPermission(Permission)

checkWrite

public void checkWrite(String filename)

Check if the current thread is allowed to write the given file. This method is called from FileOutputStream.FileOutputStream(), RandomAccessFile.RandomAccessFile(), File.canWrite(), mkdir(), and renameTo(). The default implementation checks FilePermission(filename, "write"). If you override this, call super.checkWrite rather than throwing an exception.

Parameters:

filename - the full name of the file to access

Throws:

SecurityException - if permission is denied

NullPointerException - if filename is null

See Also:

File, File#canWrite(), File#mkdir(), File#renameTo(), FileOutputStream#FileOutputStream(String), RandomAccessFile#RandomAccessFile(String)

checkDelete

public void checkDelete(String filename)

Check if the current thread is allowed to delete the given file. This method is called from File.delete(). The default implementation checks FilePermission(filename, "delete"). If you override this, call super.checkDelete rather than throwing an exception.

Parameters:

filename - the full name of the file to delete

Throws:

SecurityException - if permission is denied

NullPointerException - if filename is null

See Also:

File#delete()

checkConnect

public void checkConnect(String host,
                         int port)

Check if the current thread is allowed to connect to a given host on a given port. This method is called from Socket.Socket(). A port number of -1 indicates the caller is attempting to determine an IP address, so the default implementation checks SocketPermission(host, "resolve"). Otherwise, the default implementation checks SocketPermission(host + ":" + port, "connect"). If you override this, call super.checkConnect rather than throwing an exception.

Parameters:

host - the host to connect to

port - the port to connect on

Throws:

SecurityException - if permission is denied

NullPointerException - if host is null

See Also:

Socket#Socket()

checkConnect

public void checkConnect(String host,
                         int port,
                         Object securityContext)

Check if the current thread is allowed to connect to a given host on a given port, using the given security context. The context must be a result of a previous call to getSecurityContext. A port number of -1 indicates the caller is attempting to determine an IP address, so the default implementation checks AccessControlContext.checkPermission(new SocketPermission(host, "resolve")). Otherwise, the default implementation checks AccessControlContext.checkPermission(new SocketPermission(host + ":" + port, "connect")). If you override this, call super.checkConnect rather than throwing an exception.

Parameters:

host - the host to connect to

port - the port to connect on

Throws:

SecurityException - if permission is denied, or if context is not an AccessControlContext

NullPointerException - if host is null

See Also:

getSecurityContext(), AccessControlContext#checkPermission(Permission)

checkListen

public void checkListen(int port)

Check if the current thread is allowed to listen to a specific port for data. This method is called by ServerSocket.ServerSocket(). The default implementation checks SocketPermission("localhost:" + (port == 0 ? "1024-" : "" + port), "listen"). If you override this, call super.checkListen rather than throwing an exception.

Parameters:

port - the port to listen on

Throws:

SecurityException - if permission is denied

See Also:

ServerSocket#ServerSocket(int)

checkAccept

public void checkAccept(String host,
                        int port)

Check if the current thread is allowed to accept a connection from a particular host on a particular port. This method is called by ServerSocket.implAccept(). The default implementation checks SocketPermission(host + ":" + port, "accept"). If you override this, call super.checkAccept rather than throwing an exception.

Parameters:

host - the host which wishes to connect

port - the port the connection will be on

Throws:

SecurityException - if permission is denied

NullPointerException - if host is null

See Also:

ServerSocket#accept()

checkPropertiesAccess

public void checkPropertiesAccess()

Check if the current thread is allowed to read or write all the system properties at once. This method is called by System.getProperties() and setProperties(). The default implementation checks PropertyPermission("*", "read,write"). If you override this, call super.checkPropertiesAccess rather than throwing an exception.

Throws:

SecurityException - if permission is denied

See Also:

System#getProperties(), System#setProperties(Properties)

checkPropertyAccess

public void checkPropertyAccess(String key)

Check if the current thread is allowed to read a particular system property (writes are checked directly via checkPermission). This method is called by System.getProperty() and setProperty(). The default implementation checks PropertyPermission(key, "read"). If you override this, call super.checkPropertyAccess rather than throwing an exception.

Throws:

SecurityException - if permission is denied

NullPointerException - if key is null

IllegalArgumentException - if key is ""

See Also:

System.getProperty(String)

checkTopLevelWindow

public boolean checkTopLevelWindow(Object window)

Check if the current thread is allowed to create a top-level window. If it is not, the operation should still go through, but some sort of nonremovable warning should be placed on the window to show that it is untrusted. This method is called by Window.Window().

Parameters:

window - the window to create

Returns:

true if there is permission to show the window without warning

Throws:

NullPointerException - if window is null

See Also:

Window#Window(Frame)

checkPrintJobAccess

public void checkPrintJobAccess()

Check if the current thread is allowed to create a print job. This method is called by Toolkit.getPrintJob(). The default implementation checks RuntimePermission("queuePrintJob"). If you override this, call super.checkPrintJobAccess rather than throwing an exception.

Throws:

SecurityException - if permission is denied

Since:

1.1

See Also:

Toolkit#getPrintJob(Frame, String, Properties)

checkSystemClipboardAccess

public void checkSystemClipboardAccess()

Check if the current thread is allowed to use the system clipboard. This method is called by Toolkit.getSystemClipboard(). The default implementation checks AWTPermission("accessClipboard"). If you override this, call super.checkSystemClipboardAccess rather than throwing an exception.

Throws:

SecurityException - if permission is denied

Since:

1.1

See Also:

Toolkit#getSystemClipboard()

checkPackageAccess

public void checkPackageAccess(String packageName)

Check if the current thread is allowed to access the specified package at all. This method is called by ClassLoader.loadClass() in user-created ClassLoaders. The default implementation gets a list of all restricted packages, via Security.getProperty("package.access"). Then, if packageName starts with or equals any restricted package, it checks RuntimePermission("accessClassInPackage." + packageName). If you override this, you should call super.checkPackageAccess before doing anything else.

Parameters:

packageName - the package name to check access to

Throws:

SecurityException - if permission is denied

NullPointerException - if packageName is null

See Also:

ClassLoader.loadClass(String, boolean), Security#getProperty(String)

checkPackageDefinition

public void checkPackageDefinition(String packageName)

Check if the current thread is allowed to define a class into the specified package. This method is called by ClassLoader.loadClass() in user-created ClassLoaders. The default implementation gets a list of all restricted packages, via Security.getProperty("package.definition"). Then, if packageName starts with or equals any restricted package, it checks RuntimePermission("defineClassInPackage." + packageName). If you override this, you should call super.checkPackageDefinition before doing anything else.

Parameters:

packageName - the package name to check access to

Throws:

SecurityException - if permission is denied

NullPointerException - if packageName is null

See Also:

ClassLoader.loadClass(String, boolean), Security#getProperty(String)

checkSetFactory

public void checkSetFactory()

Check if the current thread is allowed to set the current socket factory. This method is called by Socket.setSocketImplFactory(), ServerSocket.setSocketFactory(), and URL.setURLStreamHandlerFactory(). The default implementation checks RuntimePermission("setFactory"). If you override this, call super.checkSetFactory rather than throwing an exception.

Throws:

SecurityException - if permission is denied

See Also:

Socket#setSocketImplFactory(SocketImplFactory), ServerSocket#setSocketFactory(SocketImplFactory), URL#setURLStreamHandlerFactory(URLStreamHandlerFactory)

checkMemberAccess

public void checkMemberAccess(Class c,
                              int memberType)

Check if the current thread is allowed to get certain types of Methods, Fields and Constructors from a Class object. This method is called by Class.getMethod[s](), Class.getField[s](), Class.getConstructor[s], Class.getDeclaredMethod[s](), Class.getDeclaredField[s](), and Class.getDeclaredConstructor[s](). The default implementation allows PUBLIC access, and access to classes defined by the same classloader as the code performing the reflection. Otherwise, it checks RuntimePermission("accessDeclaredMembers"). If you override this, do not call super.checkMemberAccess, as this would mess up the stack depth check that determines the ClassLoader requesting the access.

Parameters:

c - the Class to check

memberType - either DECLARED or PUBLIC

Throws:

SecurityException - if permission is denied, including when memberType is not DECLARED or PUBLIC

NullPointerException - if c is null

Since:

1.1

See Also:

Class, Member#DECLARED, Member#PUBLIC

checkSecurityAccess

public void checkSecurityAccess(String action)

Test whether a particular security action may be taken. The default implementation checks SecurityPermission(action). If you override this, call super.checkSecurityAccess rather than throwing an exception.

Parameters:

action - the desired action to take

Throws:

SecurityException - if permission is denied

NullPointerException - if action is null

IllegalArgumentException - if action is ""

Since:

1.1