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java.lang

Class SecurityManager

java.lang.Object
|
+--java.lang.SecurityManager


public 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 in 1.1, 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.

The special method checkPermission is a catchall, and the default implementation calls AccessController.checkPermission. In fact, all the other methods default to calling checkPermission.

Sometimes, the security check needs to happen from a different context, such as when called from a worker thread. In such cases, use getSecurityContext to take a snapshot that can be passed to the worker thread:

 Object context = null;
 SecurityManager sm = System.getSecurityManager();
 if (sm != null)
   context = sm.getSecurityContext(); // defaults to an AccessControlContext
 // now, in worker thread
 if (sm != null)
   sm.checkPermission(permission, context);
 

 

Permissions fall into these categories: File, Socket, Net, Security, Runtime, Property, AWT, Reflect, and Serializable. Each of these permissions have a property naming convention, that follows a hierarchical naming convention, to make it easy to grant or deny several permissions at once. Some permissions also take a list of permitted actions, such as "read" or "write", to fine-tune control even more. The permission java.security.AllPermission grants all permissions.

The default methods in this class deny all things to all people. You must explicitly grant permission for anything you want to be legal when subclassing this class.

Since:Authors:See Also:

Field Summary

booleaninCheck

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

Constructor Summary

SecurityManager()

Construct a new security manager.

Method Summary

voidcheckAccept(java.lang.String host, int port)

Check if the current thread is allowed to accept a connection from a particular host on a particular port.
voidcheckAccess(java.lang.Thread t)

Check if the current thread is allowed to modify another Thread.
voidcheckAccess(java.lang.ThreadGroup g)

Check if the current thread is allowed to modify a ThreadGroup.
voidcheckAwtEventQueueAccess()

Check if the current thread is allowed to use the AWT event queue.
voidcheckConnect(java.lang.String host, int port)

Check if the current thread is allowed to connect to a given host on a given port.
voidcheckConnect(java.lang.String host, int port, java.lang.Object securityContext)

Check if the current thread is allowed to connect to a given host on a given port, using the given security context.
voidcheckCreateClassLoader()

Check if the current thread is allowed to create a ClassLoader.
voidcheckDelete(java.lang.String filename)

Check if the current thread is allowed to delete the given file.
voidcheckExec(java.lang.String program)

Check if the current thread is allowed to execute the given program.
voidcheckExit(int status)

Check if the current thread is allowed to exit the JVM with the given status.
voidcheckLink(java.lang.String filename)

Check if the current thread is allowed to link in the given native library.
voidcheckListen(int port)

Check if the current thread is allowed to listen to a specific port for data.
voidcheckMemberAccess(java.lang.Class c, int memberType)

Check if the current thread is allowed to get certain types of Methods, Fields and Constructors from a Class object.
voidcheckMulticast(java.net.InetAddress addr)

Check if the current thread is allowed to read and write multicast to a particular address.
voidcheckMulticast(java.net.InetAddress addr, byte ttl)

Check if the current thread is allowed to read and write multicast to a particular address with a particular ttl (time-to-live) value.
voidcheckPackageAccess(java.lang.String packageName)

Check if the current thread is allowed to access the specified package at all.
voidcheckPackageDefinition(java.lang.String packageName)

Check if the current thread is allowed to define a class into the specified package.
voidcheckPermission(java.security.Permission perm)

Check if the current thread is allowed to perform an operation that requires the specified Permission.
voidcheckPermission(java.security.Permission perm, java.lang.Object context)

Check if the current thread is allowed to perform an operation that requires the specified Permission.
voidcheckPrintJobAccess()

Check if the current thread is allowed to create a print job.
voidcheckPropertiesAccess()

Check if the current thread is allowed to read or write all the system properties at once.
voidcheckPropertyAccess(java.lang.String key)

Check if the current thread is allowed to read a particular system property (writes are checked directly via checkPermission).
voidcheckRead(java.io.FileDescriptor desc)

Check if the current thread is allowed to read the given file using the FileDescriptor.
voidcheckRead(java.lang.String filename)

Check if the current thread is allowed to read the given file.
voidcheckRead(java.lang.String filename, java.lang.Object context)

Check if the current thread is allowed to read the given file.
voidcheckSecurityAccess(java.lang.String action)

Test whether a particular security action may be taken.
voidcheckSetFactory()

Check if the current thread is allowed to set the current socket factory.
voidcheckSystemClipboardAccess()

Check if the current thread is allowed to use the system clipboard.
booleancheckTopLevelWindow(java.lang.Object window)

Check if the current thread is allowed to create a top-level window.
voidcheckWrite(java.io.FileDescriptor desc)

Check if the current thread is allowed to write the given file using the FileDescriptor.
voidcheckWrite(java.lang.String filename)

Check if the current thread is allowed to write the given file.
intclassDepth(java.lang.String className)

Get the depth of a particular class on the execution stack.
intclassLoaderDepth()

Get the depth on the execution stack of the most recent non-system class.
java.lang.ClassLoadercurrentClassLoader()

Find the ClassLoader of the first non-system class on the execution stack.
java.lang.ClasscurrentLoadedClass()

Find the first non-system class on the execution stack.
java.lang.Class[]getClassContext()

Get a list of all the classes currently executing methods on the Java stack.
booleangetInCheck()

Tells whether or not the SecurityManager is currently performing a security check.
java.lang.ObjectgetSecurityContext()

Get an implementation-dependent Object that contains enough information about the current environment to be able to perform standard security checks later.
java.lang.ThreadGroupgetThreadGroup()

Get the ThreadGroup that a new Thread should belong to by default.
booleaninClass(java.lang.String className)

Tell whether the specified class is on the execution stack.
booleaninClassLoader()

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

Field Details

inCheck

protected boolean inCheck

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


Constructor Details

SecurityManager

public SecurityManager()

Construct a new security manager. There may be a security check, of RuntimePermission("createSecurityManager").

Throws:


Method Details

checkAccept

public void checkAccept(java.lang.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:

Throws:

See Also:


checkAccess

public void checkAccess(java.lang.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:

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checkAccess

public void checkAccess(java.lang.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:

Throws:

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checkAwtEventQueueAccess

public void checkAwtEventQueueAccess()

Check if the current thread is allowed to use the AWT event queue. This method is called by Toolkit.getSystemEventQueue(). The default implementation checks AWTPermission("accessEventQueue"). you override this, call super.checkAwtEventQueueAccess rather than throwing an exception.

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checkConnect

public void checkConnect(java.lang.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:

Throws:

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checkConnect

public void checkConnect(java.lang.String host, int port, java.lang.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:

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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.

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checkDelete

public void checkDelete(java.lang.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:

Throws:

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checkExec

public void checkExec(java.lang.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:

Throws:

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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:

Throws:

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checkLink

public void checkLink(java.lang.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:

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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:

Throws:

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checkMemberAccess

public void checkMemberAccess(java.lang.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.

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checkMulticast

public void checkMulticast(java.net.InetAddress addr)

Check if the current thread is allowed to read and write multicast to a particular address. The default implementation checks SocketPermission(addr.getHostAddress(), "accept,connect"). If you override this, call super.checkMulticast rather than throwing an exception.

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checkMulticast

public void checkMulticast(java.net.InetAddress addr, byte ttl)

Check if the current thread is allowed to read and write multicast to a particular address with a particular ttl (time-to-live) value. The default implementation ignores ttl, and checks SocketPermission(addr.getHostAddress(), "accept,connect"). If you override this, call super.checkMulticast rather than throwing an exception.

Since:Parameters:

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checkPackageAccess

public void checkPackageAccess(java.lang.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.

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checkPackageDefinition

public void checkPackageDefinition(java.lang.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:

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checkPermission

public void checkPermission(java.security.Permission perm)

Check if the current thread is allowed to perform an operation that requires the specified Permission. This defaults to AccessController.checkPermission.

Since:Parameters:

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checkPermission

public void checkPermission(java.security.Permission perm, java.lang.Object context)

Check if the current thread is allowed to perform an operation that requires the specified Permission. This is done in a context previously returned by getSecurityContext(). The default implementation expects context to be an AccessControlContext, and it calls AccessControlContext.checkPermission(perm).

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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.

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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.

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checkPropertyAccess

public void checkPropertyAccess(java.lang.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.

Parameters:

Throws:

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checkRead

public void checkRead(java.io.FileDescriptor desc)

Check if the current thread is allowed to read the given file using the FileDescriptor. This method is called from FileInputStream.FileInputStream(). The default implementation checks RuntimePermission("readFileDescriptor"). If you override this, call super.checkRead rather than throwing an exception.

Parameters:

Throws:

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checkRead

public void checkRead(java.lang.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:

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checkRead

public void checkRead(java.lang.String filename, java.lang.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:

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checkSecurityAccess

public void checkSecurityAccess(java.lang.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.

Since:Parameters:

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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.

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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.

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checkTopLevelWindow

public boolean checkTopLevelWindow(java.lang.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(). The default implementation checks AWTPermission("showWindowWithoutWarningBanner"), and returns true if no exception was thrown. If you override this, use return super.checkTopLevelWindow rather than returning false.

Parameters:

Returns:

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checkWrite

public void checkWrite(java.io.FileDescriptor desc)

Check if the current thread is allowed to write the given file using the FileDescriptor. This method is called from FileOutputStream.FileOutputStream(). The default implementation checks RuntimePermission("writeFileDescriptor"). If you override this, call super.checkWrite rather than throwing an exception.

Parameters:

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checkWrite

public void checkWrite(java.lang.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:

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classDepth

protected int classDepth(java.lang.String className)

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

Parameters:

Returns:


classLoaderDepth

protected int classLoaderDepth()

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:


    currentClassLoader

    protected ClassLoader currentClassLoader()

    Find the ClassLoader of 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. This will return null 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:


    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. This will return null 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:


    getClassContext

    protected 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:


    getInCheck

    public boolean getInCheck()

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

    Returns:

    See Also:


    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:

    See Also:


    getThreadGroup

    public ThreadGroup getThreadGroup()

    Get the ThreadGroup that a new Thread should belong to by default. Called by Thread.Thread(). The default implementation returns the current ThreadGroup of the current Thread. Spec Note: it is not clear whether the new Thread is guaranteed to pass the checkAccessThreadGroup() test when using this ThreadGroup, but I presume so.

    Since:Returns:


    inClass

    protected boolean inClass(java.lang.String className)

    Tell whether the specified class is on the execution stack.

    Parameters:

    Returns:


    inClassLoader

    protected boolean inClassLoader()

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

    Returns: