/*

 * Copyright 1999-2007 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package javax.crypto;

import java.security.*;

import java.net.*;

import java.util.*;

import java.util.jar.*;

/**

 * The JCE security manager.

 *

 * <p>The JCE security manager is responsible for determining the maximum

 * allowable cryptographic strength for a given applet/application, for a given

 * algorithm, by consulting the configured jurisdiction policy files and

 * the cryptographic permissions bundled with the applet/application.

 *

 * <p>Note that this security manager is never installed, only instantiated.

 *

 * @author Jan Luehe

 *

 * @since 1.4

 */

final class JceSecurityManager extends SecurityManager {

    private static final CryptoPermissions defaultPolicy;

    private static final CryptoPermissions exemptPolicy;

    private static final CryptoAllPermission allPerm;

    private static final Vector TrustedCallersCache = new Vector(2);

    private static final Map exemptCache = new HashMap();

    // singleton instance

    static final JceSecurityManager INSTANCE;

    static {

        defaultPolicy = JceSecurity.getDefaultPolicy();

        exemptPolicy = JceSecurity.getExemptPolicy();

        allPerm = CryptoAllPermission.INSTANCE;

        INSTANCE = (JceSecurityManager)

              AccessController.doPrivileged(new PrivilegedAction() {

                  public Object run() {

                      return new JceSecurityManager();

                  }

              });

    }

    private JceSecurityManager() {

        // empty

    }

    /**

     * Returns the maximum allowable crypto strength for the given

     * applet/application, for the given algorithm.

     */

    CryptoPermission getCryptoPermission(String alg) {

        // Need to convert to uppercase since the crypto perm

        // lookup is case sensitive.

        alg = alg.toUpperCase(Locale.ENGLISH);

        // If CryptoAllPermission is granted by default, we return that.

        // Otherwise, this will be the permission we return if anything goes

        // wrong.

        CryptoPermission defaultPerm = getDefaultPermission(alg);

        if (defaultPerm == CryptoAllPermission.INSTANCE) {

            return defaultPerm;

        }

        // Determine the codebase of the caller of the JCE API.

        // This is the codebase of the first class which is not in

        // javax.crypto.* packages.

        // NOTE: javax.crypto.* package maybe subject to package

        // insertion, so need to check its classloader as well.

        Class[] context = getClassContext();

        URL callerCodeBase = null;

        int i;

        for (i=0; i<context.length; i++) {

            Class cls = context[i];

            callerCodeBase = JceSecurity.getCodeBase(cls);

            if (callerCodeBase != null) {

                break;

            } else {

                if (cls.getName().startsWith("javax.crypto.")) {

                    // skip jce classes since they aren't the callers

                    continue;

                }

                // use default permission when the caller is system classes

                return defaultPerm;

            }

        }

        if (i == context.length) {

            return defaultPerm;

        }

        CryptoPermissions appPerms;

        synchronized (this.getClass()) {

            if (exemptCache.containsKey(callerCodeBase)) {

                appPerms = (CryptoPermissions)exemptCache.get(callerCodeBase);

            } else {

                appPerms = getAppPermissions(callerCodeBase);

                exemptCache.put(callerCodeBase, appPerms);

            }

        }

        if (appPerms == null) {

            return defaultPerm;

        }

        // If the app was granted the special CryptoAllPermission, return that.

        if (appPerms.implies(allPerm)) {

            return allPerm;

        }

        // Check if the crypto permissions granted to the app contain a

        // crypto permission for the requested algorithm that does not require

        // any exemption mechanism to be enforced.

        // Return that permission, if present.

        PermissionCollection appPc = appPerms.getPermissionCollection(alg);

        if (appPc == null) {

            return defaultPerm;

        }

        Enumeration enum_ = appPc.elements();

        while (enum_.hasMoreElements()) {

            CryptoPermission cp = (CryptoPermission)enum_.nextElement();

            if (cp.getExemptionMechanism() == null) {

                return cp;

            }

        }

        // Check if the jurisdiction file for exempt applications contains

        // any entries for the requested algorithm.

        // If not, return the default permission.

        PermissionCollection exemptPc =

            exemptPolicy.getPermissionCollection(alg);

        if (exemptPc == null) {

            return defaultPerm;

        }

        // In the jurisdiction file for exempt applications, go through the

        // list of CryptoPermission entries for the requested algorithm, and

        // stop at the first entry:

        //  - that is implied by the collection of crypto permissions granted

        //    to the app, and

        //  - whose exemption mechanism is available from one of the

        //    registered CSPs

        enum_ = exemptPc.elements();

        while (enum_.hasMoreElements()) {

            CryptoPermission cp = (CryptoPermission)enum_.nextElement();

            try {

                ExemptionMechanism.getInstance(cp.getExemptionMechanism());

                if (cp.getAlgorithm().equals(

                                      CryptoPermission.ALG_NAME_WILDCARD)) {

                    CryptoPermission newCp;

                    if (cp.getCheckParam()) {

                        newCp = new CryptoPermission(

                                alg, cp.getMaxKeySize(),

                                cp.getAlgorithmParameterSpec(),

                                cp.getExemptionMechanism());

                    } else {

                        newCp = new CryptoPermission(

                                alg, cp.getMaxKeySize(),

                                cp.getExemptionMechanism());

                    }

                    if (appPerms.implies(newCp)) {

                        return newCp;

                    }

                }

                if (appPerms.implies(cp)) {

                    return cp;

                }

            } catch (Exception e) {

                continue;

            }

        }

        return defaultPerm;

    }

    private static CryptoPermissions getAppPermissions(URL callerCodeBase) {

        // Check if app is exempt, and retrieve the permissions bundled with it

        try {

            return JceSecurity.verifyExemptJar(callerCodeBase);

        } catch (Exception e) {

            // Jar verification fails

            return null;

        }

    }

    /**

     * Returns the default permission for the given algorithm.

     */

    private CryptoPermission getDefaultPermission(String alg) {

        Enumeration enum_ =

            defaultPolicy.getPermissionCollection(alg).elements();

        return (CryptoPermission)enum_.nextElement();

    }

    // See  bug 4341369 & 4334690 for more info.

    boolean isCallerTrusted() {

        // Get the caller and its codebase.

        Class[] context = getClassContext();

        URL callerCodeBase = null;

        int i;

        for (i=0; i<context.length; i++) {

            callerCodeBase = JceSecurity.getCodeBase(context[i]);

            if (callerCodeBase != null) {

                break;

            }

        }

        // The caller is in the JCE framework.

        if (i == context.length) {

            return true;

        }

        //The caller has been verified.

        if (TrustedCallersCache.contains(context[i])) {

            return true;

        }

        // Check whether the caller is a trusted provider.

        try {

            JceSecurity.verifyProviderJar(callerCodeBase);

        } catch (Exception e2) {

            return false;

        }

        TrustedCallersCache.addElement(context[i]);

        return true;

    }

}