如何创建Java沙箱?

时间:2009-11-11 12:57:43

标签: java security plugins sandbox

我想让我的应用程序运行其他人的代码,即插件。但是,我有什么选择才能使其安全,因此他们不会编写恶意代码。我如何控制他们能做什么或不能做什么?

我偶然发现JVM有一个“内置沙盒”功能 - 它是什么,这是唯一的方法吗?是否有用于制作沙箱的第三方Java库?

我有哪些选择?赞赏指南和示例的链接!

7 个答案:

答案 0 :(得分:23)

您正在寻找security manager。您可以通过指定policy来限制应用程序的权限。

答案 1 :(得分:18)

  • 定义并注册您自己的安全管理器将允许您限制代码的作用 - 请参阅SecurityManager的oracle文档。

  • 另外,请考虑创建一个单独的机制来加载代码 - 即您可以编写或实例化另一个类加载器以从特殊位置加载代码。您可能有一个加载代码的约定 - 例如从特殊目录或特殊格式的zip文件(作为WAR文件和JAR文件)。如果您正在编写一个类加载器,它会使您处于必须完成工作以加载代码的位置。这意味着如果您想要拒绝某些内容(或某些依赖项),则无法加载代码。 http://java.sun.com/javase/6/docs/api/java/lang/ClassLoader.html

答案 2 :(得分:5)

查看the java-sandbox project,它可以轻松创建非常灵活的沙箱来运行不受信任的代码。

答案 3 :(得分:4)

对于AWT / Swing应用程序,您需要使用非标准AppContext类,它可能随时更改。因此,为了有效,您需要启动另一个进程来运行插件代码,并处理两者之间的通信(有点像Chrome)。插件流程需要SecurityManager集和ClassLoader来隔离插件代码并将适当的ProtectionDomain应用于插件类。

答案 4 :(得分:3)

以下是使用SecurityManager解决问题的方法:

https://svn.code.sf.net/p/loggifier/code/trunk/de.unkrig.commons.lang/src/de/unkrig/commons/lang/security/Sandbox.java

package de.unkrig.commons.lang.security;

import java.security.AccessControlContext;
import java.security.Permission;
import java.security.Permissions;
import java.security.ProtectionDomain;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.WeakHashMap;

import de.unkrig.commons.nullanalysis.Nullable;

/**
 * This class establishes a security manager that confines the permissions for code executed through specific classes,
 * which may be specified by class, class name and/or class loader.
 * <p>
 * To 'execute through a class' means that the execution stack includes the class. E.g., if a method of class {@code A}
 * invokes a method of class {@code B}, which then invokes a method of class {@code C}, and all three classes were
 * previously {@link #confine(Class, Permissions) confined}, then for all actions that are executed by class {@code C}
 * the <i>intersection</i> of the three {@link Permissions} apply.
 * <p>
 * Once the permissions for a class, class name or class loader are confined, they cannot be changed; this prevents any
 * attempts (e.g. of the confined class itself) to release the confinement.
 * <p>
 * Code example:
 * <pre>
 *  Runnable unprivileged = new Runnable() {
 *      public void run() {
 *          System.getProperty("user.dir");
 *      }
 *  };
 *
 *  // Run without confinement.
 *  unprivileged.run(); // Works fine.
 *
 *  // Set the most strict permissions.
 *  Sandbox.confine(unprivileged.getClass(), new Permissions());
 *  unprivileged.run(); // Throws a SecurityException.
 *
 *  // Attempt to change the permissions.
 *  {
 *      Permissions permissions = new Permissions();
 *      permissions.add(new AllPermission());
 *      Sandbox.confine(unprivileged.getClass(), permissions); // Throws a SecurityException.
 *  }
 *  unprivileged.run();
 * </pre>
 */
public final
class Sandbox {

    private Sandbox() {}

    private static final Map<Class<?>, AccessControlContext>
    CHECKED_CLASSES = Collections.synchronizedMap(new WeakHashMap<Class<?>, AccessControlContext>());

    private static final Map<String, AccessControlContext>
    CHECKED_CLASS_NAMES = Collections.synchronizedMap(new HashMap<String, AccessControlContext>());

    private static final Map<ClassLoader, AccessControlContext>
    CHECKED_CLASS_LOADERS = Collections.synchronizedMap(new WeakHashMap<ClassLoader, AccessControlContext>());

    static {

        // Install our custom security manager.
        if (System.getSecurityManager() != null) {
            throw new ExceptionInInitializerError("There's already a security manager set");
        }
        System.setSecurityManager(new SecurityManager() {

            @Override public void
            checkPermission(@Nullable Permission perm) {
                assert perm != null;

                for (Class<?> clasS : this.getClassContext()) {

                    // Check if an ACC was set for the class.
                    {
                        AccessControlContext acc = Sandbox.CHECKED_CLASSES.get(clasS);
                        if (acc != null) acc.checkPermission(perm);
                    }

                    // Check if an ACC was set for the class name.
                    {
                        AccessControlContext acc = Sandbox.CHECKED_CLASS_NAMES.get(clasS.getName());
                        if (acc != null) acc.checkPermission(perm);
                    }

                    // Check if an ACC was set for the class loader.
                    {
                        AccessControlContext acc = Sandbox.CHECKED_CLASS_LOADERS.get(clasS.getClassLoader());
                        if (acc != null) acc.checkPermission(perm);
                    }
                }
            }
        });
    }

    // --------------------------

    /**
     * All future actions that are executed through the given {@code clasS} will be checked against the given {@code
     * accessControlContext}.
     *
     * @throws SecurityException Permissions are already confined for the {@code clasS}
     */
    public static void
    confine(Class<?> clasS, AccessControlContext accessControlContext) {

        if (Sandbox.CHECKED_CLASSES.containsKey(clasS)) {
            throw new SecurityException("Attempt to change the access control context for '" + clasS + "'");
        }

        Sandbox.CHECKED_CLASSES.put(clasS, accessControlContext);
    }

    /**
     * All future actions that are executed through the given {@code clasS} will be checked against the given {@code
     * protectionDomain}.
     *
     * @throws SecurityException Permissions are already confined for the {@code clasS}
     */
    public static void
    confine(Class<?> clasS, ProtectionDomain protectionDomain) {
        Sandbox.confine(
            clasS,
            new AccessControlContext(new ProtectionDomain[] { protectionDomain })
        );
    }

    /**
     * All future actions that are executed through the given {@code clasS} will be checked against the given {@code
     * permissions}.
     *
     * @throws SecurityException Permissions are already confined for the {@code clasS}
     */
    public static void
    confine(Class<?> clasS, Permissions permissions) {
        Sandbox.confine(clasS, new ProtectionDomain(null, permissions));
    }

    // Code for 'CHECKED_CLASS_NAMES' and 'CHECKED_CLASS_LOADERS' omitted here.

}

答案 5 :(得分:0)

关于这个问题的讨论激发了我启动自己的沙盒项目。

https://github.com/Black-Mantha/sandbox

其中我遇到了一个重要的安全问题:“如何让沙箱外的代码绕过SecurityManager?”

我将沙盒代码放在自己的ThreadGroup中,并且在该组外部时始终授予权限。如果您仍需要在该组中运行特权代码(例如,在回调中),则可以使用ThreadLocal仅为该Thread设置标志。类加载器将阻止沙箱访问ThreadLocal。另外,如果你这样做,你需要禁止使用终结器,因为它们在ThreadGroup外部的专用线程中运行。

答案 6 :(得分:0)

花了一天的时间深入研究Java安全API之后,我发现了一个非常简单的解决方案,用于在Permissions限制的沙箱中执行不受信任的代码:

https://github.com/janino-compiler/janino/blob/master/commons-compiler/src/main/java/org/codehaus/commons/compiler/Sandbox.java

这是(简化的)源代码:

package org.codehaus.commons.compiler;

import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.Permission;
import java.security.PermissionCollection;
import java.security.Policy;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.security.ProtectionDomain;

public final
class Sandbox {

    static {

        if (System.getSecurityManager() == null) {

            // Before installing the security manager, configure a decent ("positive") policy.
           Policy.setPolicy(new Policy() {

                @Override public boolean
                implies(ProtectionDomain domain, Permission permission) { return true; }
            });

            System.setSecurityManager(new SecurityManager());
        }
    }

    private final AccessControlContext accessControlContext;

    /**
     * @param permissions Will be applied on later calls to {@link #confine(PrivilegedAction)} and {@link
     *                    #confine(PrivilegedExceptionAction)}
     */
    public
    Sandbox(PermissionCollection permissions) {
        this.accessControlContext = new AccessControlContext(new ProtectionDomain[] {
            new ProtectionDomain(null, permissions)
        });
    }

    /**
     * Runs the given <var>action</var>, confined by the permissions configured through the {@link
     * #Sandbox(PermissionCollection) constructor}.
     *
     * @return The value returned by the <var>action</var>
     */
    public <R> R
    confine(PrivilegedAction<R> action) {
        return AccessController.doPrivileged(action, this.accessControlContext);
    }

    public <R> R
    confine(PrivilegedExceptionAction<R> action) throws Exception {
        try {
            return AccessController.doPrivileged(action, this.accessControlContext);
        } catch (PrivilegedActionException pae) {
            throw pae.getException();
        }
    }
}