RuntimePermission (Java 2 Platform SE v1.4.1) - JDK 5 Documentation v1.4.1, Java 2 SDK 英文文档

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Java^TM 2 Platform
Std. Ed. v1.4.1

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java.lang
Class RuntimePermission

java.lang.Object
  |
  +--java.security.Permission
        |
        +--java.security.BasicPermission
              |
              +--java.lang.RuntimePermission

All Implemented Interfaces:: Guard, Serializable

public final class RuntimePermission
extends BasicPermission

This class is for runtime permissions. A RuntimePermission contains a name (also referred to as a "target name") but no actions list; you either have the named permission or you don't.

The target name is the name of the runtime permission (see below). The naming convention follows the hierarchical property naming convention. Also, an asterisk may appear at the end of the name, following a ".", or by itself, to signify a wildcard match. For example: "loadLibrary.*" or "*" is valid, "*loadLibrary" or "a*b" is not valid.

The following table lists all the possible RuntimePermission target names, and for each provides a description of what the permission allows and a discussion of the risks of granting code the permission.

Permission Target Name What the Permission Allows Risks of Allowing this Permission

createClassLoader Creation of a class loader This is an extremely dangerous permission to grant. Malicious applications that can instantiate their own class loaders could then load their own rogue classes into the system. These newly loaded classes could be placed into any protection domain by the class loader, thereby automatically granting the classes the permissions for that domain.

getClassLoader Retrieval of a class loader (e.g., the class loader for the calling class) This would grant an attacker permission to get the class loader for a particular class. This is dangerous because having access to a class's class loader allows the attacker to load other classes available to that class loader. The attacker would typically otherwise not have access to those classes.

setContextClassLoader Setting of the context class loader used by a thread The context class loader is used by system code and extensions when they need to lookup resources that might not exist in the system class loader. Granting setContextClassLoader permission would allow code to change which context class loader is used for a particular thread, including system threads.

setSecurityManager Setting of the security manager (possibly replacing an existing one) The security manager is a class that allows applications to implement a security policy. Granting the setSecurityManager permission would allow code to change which security manager is used by installing a different, possibly less restrictive security manager, thereby bypassing checks that would have been enforced by the original security manager.

createSecurityManager Creation of a new security manager This gives code access to protected, sensitive methods that may disclose information about other classes or the execution stack.

exitVM Halting of the Java Virtual Machine This allows an attacker to mount a denial-of-service attack by automatically forcing the virtual machine to halt. Note: The "exitVM" permission is automatically granted to all code loaded from the application class path, thus enabling applications to terminate themselves.

shutdownHooks Registration and cancellation of virtual-machine shutdown hooks This allows an attacker to register a malicious shutdown hook that interferes with the clean shutdown of the virtual machine.

setFactory Setting of the socket factory used by ServerSocket or Socket, or of the stream handler factory used by URL This allows code to set the actual implementation for the socket, server socket, stream handler, or RMI socket factory. An attacker may set a faulty implementation which mangles the data stream.

setIO Setting of System.out, System.in, and System.err This allows changing the value of the standard system streams. An attacker may change System.in to monitor and steal user input, or may set System.err to a "null" OutputSteam, which would hide any error messages sent to System.err.

modifyThread Modification of threads, e.g., via calls to Thread stop, suspend, resume, setPriority, and setName methods This allows an attacker to start or suspend any thread in the system.

stopThread Stopping of threads via calls to the Thread stop method This allows code to stop any thread in the system provided that it is already granted permission to access that thread. This poses as a threat, because that code may corrupt the system by killing existing threads.

modifyThreadGroup modification of thread groups, e.g., via calls to ThreadGroup destroy, getParent, resume, setDaemon, setMaxPriority, stop, and suspend methods This allows an attacker to create thread groups and set their run priority.

getProtectionDomain Retrieval of the ProtectionDomain for a class This allows code to obtain policy information for a particular code source. While obtaining policy information does not compromise the security of the system, it does give attackers additional information, such as local file names for example, to better aim an attack.

readFileDescriptor Reading of file descriptors This would allow code to read the particular file associated with the file descriptor read. This is dangerous if the file contains confidential data.

writeFileDescriptor Writing to file descriptors This allows code to write to a particular file associated with the descriptor. This is dangerous because it may allow malicious code to plant viruses or at the very least, fill up your entire disk.

loadLibrary.{library name} Dynamic linking of the specified library It is dangerous to allow an applet permission to load native code libraries, because the Java security architecture is not designed to and does not prevent malicious behavior at the level of native code.

accessClassInPackage.{package name} Access to the specified package via a class loader's loadClass method when that class loader calls the SecurityManager checkPackageAcesss method This gives code access to classes in packages to which it normally does not have access. Malicious code may use these classes to help in its attempt to compromise security in the system.

defineClassInPackage.{package name} Definition of classes in the specified package, via a class loader's defineClass method when that class loader calls the SecurityManager checkPackageDefinition method. This grants code permission to define a class in a particular package. This is dangerous because malicious code with this permission may define rogue classes in trusted packages like java.security or java.lang, for example.

accessDeclaredMembers Access to the declared members of a class This grants code permission to query a class for its public, protected, default (package) access, and private fields and/or methods. Although the code would have access to the private and protected field and method names, it would not have access to the private/protected field data and would not be able to invoke any private methods. Nevertheless, malicious code may use this information to better aim an attack. Additionally, it may invoke any public methods and/or access public fields in the class. This could be dangerous if the code would normally not be able to invoke those methods and/or access the fields because it can't cast the object to the class/interface with those methods and fields.

queuePrintJob Initiation of a print job request This could print sensitive information to a printer, or simply waste paper.

Permission Target Name	What the Permission Allows	Risks of Allowing this Permission
createClassLoader	Creation of a class loader	This is an extremely dangerous permission to grant. Malicious applications that can instantiate their own class loaders could then load their own rogue classes into the system. These newly loaded classes could be placed into any protection domain by the class loader, thereby automatically granting the classes the permissions for that domain.
getClassLoader	Retrieval of a class loader (e.g., the class loader for the calling class)	This would grant an attacker permission to get the class loader for a particular class. This is dangerous because having access to a class's class loader allows the attacker to load other classes available to that class loader. The attacker would typically otherwise not have access to those classes.
setContextClassLoader	Setting of the context class loader used by a thread	The context class loader is used by system code and extensions when they need to lookup resources that might not exist in the system class loader. Granting setContextClassLoader permission would allow code to change which context class loader is used for a particular thread, including system threads.
setSecurityManager	Setting of the security manager (possibly replacing an existing one)	The security manager is a class that allows applications to implement a security policy. Granting the setSecurityManager permission would allow code to change which security manager is used by installing a different, possibly less restrictive security manager, thereby bypassing checks that would have been enforced by the original security manager.
createSecurityManager	Creation of a new security manager	This gives code access to protected, sensitive methods that may disclose information about other classes or the execution stack.
exitVM	Halting of the Java Virtual Machine	This allows an attacker to mount a denial-of-service attack by automatically forcing the virtual machine to halt. Note: The "exitVM" permission is automatically granted to all code loaded from the application class path, thus enabling applications to terminate themselves.
shutdownHooks	Registration and cancellation of virtual-machine shutdown hooks	This allows an attacker to register a malicious shutdown hook that interferes with the clean shutdown of the virtual machine.
setFactory	Setting of the socket factory used by ServerSocket or Socket, or of the stream handler factory used by URL	This allows code to set the actual implementation for the socket, server socket, stream handler, or RMI socket factory. An attacker may set a faulty implementation which mangles the data stream.
setIO	Setting of System.out, System.in, and System.err	This allows changing the value of the standard system streams. An attacker may change System.in to monitor and steal user input, or may set System.err to a "null" OutputSteam, which would hide any error messages sent to System.err.
modifyThread	Modification of threads, e.g., via calls to Thread `stop`, `suspend`, `resume`, `setPriority`, and `setName` methods	This allows an attacker to start or suspend any thread in the system.
stopThread	Stopping of threads via calls to the Thread `stop` method	This allows code to stop any thread in the system provided that it is already granted permission to access that thread. This poses as a threat, because that code may corrupt the system by killing existing threads.
modifyThreadGroup	modification of thread groups, e.g., via calls to ThreadGroup `destroy`, `getParent`, `resume`, `setDaemon`, `setMaxPriority`, `stop`, and `suspend` methods	This allows an attacker to create thread groups and set their run priority.
getProtectionDomain	Retrieval of the ProtectionDomain for a class	This allows code to obtain policy information for a particular code source. While obtaining policy information does not compromise the security of the system, it does give attackers additional information, such as local file names for example, to better aim an attack.
readFileDescriptor	Reading of file descriptors	This would allow code to read the particular file associated with the file descriptor read. This is dangerous if the file contains confidential data.
writeFileDescriptor	Writing to file descriptors	This allows code to write to a particular file associated with the descriptor. This is dangerous because it may allow malicious code to plant viruses or at the very least, fill up your entire disk.
loadLibrary.{library name}	Dynamic linking of the specified library	It is dangerous to allow an applet permission to load native code libraries, because the Java security architecture is not designed to and does not prevent malicious behavior at the level of native code.
accessClassInPackage.{package name}	Access to the specified package via a class loader's `loadClass` method when that class loader calls the SecurityManager `checkPackageAcesss` method	This gives code access to classes in packages to which it normally does not have access. Malicious code may use these classes to help in its attempt to compromise security in the system.
defineClassInPackage.{package name}	Definition of classes in the specified package, via a class loader's `defineClass` method when that class loader calls the SecurityManager `checkPackageDefinition` method.	This grants code permission to define a class in a particular package. This is dangerous because malicious code with this permission may define rogue classes in trusted packages like `java.security` or `java.lang`, for example.
accessDeclaredMembers	Access to the declared members of a class	This grants code permission to query a class for its public, protected, default (package) access, and private fields and/or methods. Although the code would have access to the private and protected field and method names, it would not have access to the private/protected field data and would not be able to invoke any private methods. Nevertheless, malicious code may use this information to better aim an attack. Additionally, it may invoke any public methods and/or access public fields in the class. This could be dangerous if the code would normally not be able to invoke those methods and/or access the fields because it can't cast the object to the class/interface with those methods and fields.
queuePrintJob	Initiation of a print job request	This could print sensitive information to a printer, or simply waste paper.

See Also:: BasicPermission, Permission, Permissions, PermissionCollection, SecurityManager, Serialized Form

Constructor Summary

RuntimePermission(String name)
Creates a new RuntimePermission with the specified name.

RuntimePermission(String name, String actions)
Creates a new RuntimePermission object with the specified name.

Methods inherited from class java.security.BasicPermission

equals, getActions, hashCode, implies, newPermissionCollection

Methods inherited from class java.security.Permission

checkGuard, getName, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail