/*

 * Copyright (c) 2005, 2017, Oracle and/or its affiliates. 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package com.sun.security.auth.module;

import java.net.SocketPermission;

import java.security.Principal;

import java.util.Arrays;

import java.util.Hashtable;

import java.util.Map;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

import java.util.Set;

import javax.naming.*;

import javax.naming.directory.*;

import javax.naming.ldap.*;

import javax.security.auth.*;

import javax.security.auth.callback.*;

import javax.security.auth.login.*;

import javax.security.auth.spi.*;

import com.sun.security.auth.LdapPrincipal;

import com.sun.security.auth.UserPrincipal;

import static sun.security.util.ResourcesMgr.getAuthResourceString;

/**

 * This {@link LoginModule} performs LDAP-based authentication.

 * A username and password is verified against the corresponding user

 * credentials stored in an LDAP directory.

 * This module requires the supplied {@link CallbackHandler} to support a

 * {@link NameCallback} and a {@link PasswordCallback}.

 * If authentication is successful then a new {@link LdapPrincipal} is created

 * using the user's distinguished name and a new {@link UserPrincipal} is

 * created using the user's username and both are associated

 * with the current {@link Subject}.

 *

 * <p> This module operates in one of three modes: <i>search-first</i>,

 * <i>authentication-first</i> or <i>authentication-only</i>.

 * A mode is selected by specifying a particular set of options.

 *

 * <p> In search-first mode, the LDAP directory is searched to determine the

 * user's distinguished name and then authentication is attempted.

 * An (anonymous) search is performed using the supplied username in

 * conjunction with a specified search filter.

 * If successful then authentication is attempted using the user's

 * distinguished name and the supplied password.

 * To enable this mode, set the {@code userFilter} option and omit the

 * {@code authIdentity} option.

 * Use search-first mode when the user's distinguished name is not

 * known in advance.

 *

 * <p> In authentication-first mode, authentication is attempted using the

 * supplied username and password and then the LDAP directory is searched.

 * If authentication is successful then a search is performed using the

 * supplied username in conjunction with a specified search filter.

 * To enable this mode, set the {@code authIdentity} and the

 * {@code userFilter} options.

 * Use authentication-first mode when accessing an LDAP directory

 * that has been configured to disallow anonymous searches.

 *

 * <p> In authentication-only mode, authentication is attempted using the

 * supplied username and password. The LDAP directory is not searched because

 * the user's distinguished name is already known.

 * To enable this mode, set the {@code authIdentity} option to a valid

 * distinguished name and omit the {@code userFilter} option.

 * Use authentication-only mode when the user's distinguished name is

 * known in advance.

 *

 * <p> The following option is mandatory and must be specified in this

 * module's login {@link Configuration}:

 * <dl>

 * <dt> <code>userProvider=<b>ldap_urls</b></code>

 * </dt>

 * <dd> This option identifies the LDAP directory that stores user entries.

 *      <b>ldap_urls</b> is a list of space-separated LDAP URLs

 *      (<a href="http://www.ietf.org/rfc/rfc2255.txt">RFC 2255</a>)

 *      that identifies the LDAP server to use and the position in

 *      its directory tree where user entries are located.

 *      When several LDAP URLs are specified then each is attempted,

 *      in turn, until the first successful connection is established.

 *      Spaces in the distinguished name component of the URL must be escaped

 *      using the standard mechanism of percent character ('{@code %}')

 *      followed by two hexadecimal digits (see {@link java.net.URI}).

 *      Query components must also be omitted from the URL.

 *

 *      <p>

 *      Automatic discovery of the LDAP server via DNS

 *      (<a href="http://www.ietf.org/rfc/rfc2782.txt">RFC 2782</a>)

 *      is supported (once DNS has been configured to support such a service).

 *      It is enabled by omitting the hostname and port number components from

 *      the LDAP URL. </dd>

 *

 * <p> This module also recognizes the following optional {@link Configuration}

 *     options:

 * <dl>

 * <dt> <code>userFilter=<b>ldap_filter</b></code> </dt>

 * <dd> This option specifies the search filter to use to locate a user's

 *      entry in the LDAP directory. It is used to determine a user's

 *      distinguished name.

 *      <b>{@code ldap_filter}</b> is an LDAP filter string

 *      (<a href="http://www.ietf.org/rfc/rfc2254.txt">RFC 2254</a>).

 *      If it contains the special token "<b>{@code {USERNAME}}</b>"

 *      then that token will be replaced with the supplied username value

 *      before the filter is used to search the directory. </dd>

 *

 * <dt> <code>authIdentity=<b>auth_id</b></code> </dt>

 * <dd> This option specifies the identity to use when authenticating a user

 *      to the LDAP directory.

 *      <b>{@code auth_id}</b> may be an LDAP distinguished name string

 *      (<a href="http://www.ietf.org/rfc/rfc2253.txt">RFC 2253</a>) or some

 *      other string name.

 *      It must contain the special token "<b>{@code {USERNAME}}</b>"

 *      which will be replaced with the supplied username value before the

 *      name is used for authentication.

 *      Note that if this option does not contain a distinguished name then

 *      the {@code userFilter} option must also be specified. </dd>

 *

 * <dt> <code>authzIdentity=<b>authz_id</b></code> </dt>

 * <dd> This option specifies an authorization identity for the user.

 *      <b>{@code authz_id}</b> is any string name.

 *      If it comprises a single special token with curly braces then

 *      that token is treated as a attribute name and will be replaced with a

 *      single value of that attribute from the user's LDAP entry.

 *      If the attribute cannot be found then the option is ignored.

 *      When this option is supplied and the user has been successfully

 *      authenticated then an additional {@link UserPrincipal}

 *      is created using the authorization identity and it is associated with

 *      the current {@link Subject}. </dd>

 *

 * <dt> {@code useSSL} </dt>

 * <dd> if {@code false}, this module does not establish an SSL connection

 *      to the LDAP server before attempting authentication. SSL is used to

 *      protect the privacy of the user's password because it is transmitted

 *      in the clear over LDAP.

 *      By default, this module uses SSL. </dd>

 *

 * <dt> {@code useFirstPass} </dt>

 * <dd> if {@code true}, this module retrieves the username and password

 *      from the module's shared state, using "javax.security.auth.login.name"

 *      and "javax.security.auth.login.password" as the respective keys. The

 *      retrieved values are used for authentication. If authentication fails,

 *      no attempt for a retry is made, and the failure is reported back to

 *      the calling application.</dd>

 *

 * <dt> {@code tryFirstPass} </dt>

 * <dd> if {@code true}, this module retrieves the username and password

 *      from the module's shared state, using "javax.security.auth.login.name"

 *       and "javax.security.auth.login.password" as the respective keys.  The

 *      retrieved values are used for authentication. If authentication fails,

 *      the module uses the {@link CallbackHandler} to retrieve a new username

 *      and password, and another attempt to authenticate is made. If the

 *      authentication fails, the failure is reported back to the calling

 *      application.</dd>

 *

 * <dt> {@code storePass} </dt>

 * <dd> if {@code true}, this module stores the username and password

 *      obtained from the {@link CallbackHandler} in the module's shared state,

 *      using

 *      "javax.security.auth.login.name" and

 *      "javax.security.auth.login.password" as the respective keys.  This is

 *      not performed if existing values already exist for the username and

 *      password in the shared state, or if authentication fails.</dd>

 *

 * <dt> {@code clearPass} </dt>

 * <dd> if {@code true}, this module clears the username and password

 *      stored in the module's shared state after both phases of authentication

 *      (login and commit) have completed.</dd>

 *

 * <dt> {@code debug} </dt>

 * <dd> if {@code true}, debug messages are displayed on the standard

 * </dl>

 *

 * <p>

 * Arbitrary

 * {@extLink jndi_ldap_gl_prop "JNDI properties"}

 * may also be specified in the {@link Configuration}.

 * They are added to the environment and passed to the LDAP provider.

 * Note that the following four JNDI properties are set by this module directly

 * and are ignored if also present in the configuration:

 * <ul>

 * <li> {@code java.naming.provider.url}

 * <li> {@code java.naming.security.principal}

 * <li> {@code java.naming.security.credentials}

 * <li> {@code java.naming.security.protocol}

 * </ul>

 *

 * <p>

 * Three sample {@link Configuration}s are shown below.

 * The first one activates search-first mode. It identifies the LDAP server

 * and specifies that users' entries be located by their {@code uid} and

 * {@code objectClass} attributes. It also specifies that an identity

 * based on the user's {@code employeeNumber} attribute should be created.

 * The second one activates authentication-first mode. It requests that the

 * LDAP server be located dynamically, that authentication be performed using

 * the supplied username directly but without the protection of SSL and that

 * users' entries be located by one of three naming attributes and their

 * {@code objectClass} attribute.

 * The third one activates authentication-only mode. It identifies alternative

 * LDAP servers, it specifies the distinguished name to use for

 * authentication and a fixed identity to use for authorization. No directory

 * search is performed.

 *

 * <pre>{@literal

 *

 *     ExampleApplication {

 *         com.sun.security.auth.module.LdapLoginModule REQUIRED

 *              userProvider="ldap://ldap-svr/ou=people,dc=example,dc=com"

 *              userFilter="(&(uid={USERNAME})(objectClass=inetOrgPerson))"

 *              authzIdentity="{EMPLOYEENUMBER}"

 *              debug=true;

 *     };

 *

 *     ExampleApplication {

 *         com.sun.security.auth.module.LdapLoginModule REQUIRED

 *             userProvider="ldap:///cn=users,dc=example,dc=com"

 *             authIdentity="{USERNAME}"

 *             userFilter="(&(|(samAccountName={USERNAME})(userPrincipalName={USERNAME})(cn={USERNAME}))(objectClass=user))"

 *             useSSL=false

 *             debug=true;

 *     };

 *

 *     ExampleApplication {

 *         com.sun.security.auth.module.LdapLoginModule REQUIRED

 *             userProvider="ldap://ldap-svr1 ldap://ldap-svr2"

 *             authIdentity="cn={USERNAME},ou=people,dc=example,dc=com"

 *             authzIdentity="staff"

 *             debug=true;

 *     };

 *

 * }</pre>

 *

 * <dl>

 * <dt><b>Note:</b> </dt>

 * <dd>When a {@link SecurityManager} is active then an application

 *     that creates a {@link LoginContext} and uses a {@link LoginModule}

 *     must be granted certain permissions.

 *     <p>

 *     If the application creates a login context using an <em>installed</em>

 *     {@link Configuration} then the application must be granted the

 *     {@link AuthPermission} to create login contexts.

 *     For example, the following security policy allows an application in

 *     the user's current directory to instantiate <em>any</em> login context:

 *     <pre>

 *

 *     grant codebase "file:${user.dir}/" {

 *         permission javax.security.auth.AuthPermission "createLoginContext.*";

 *     };

 *     </pre>

 *

 *     Alternatively, if the application creates a login context using a

 *     <em>caller-specified</em> {@link Configuration} then the application

 *     must be granted the permissions required by the {@link LoginModule}.

 *     <em>This</em> module requires the following two permissions:

 *     <ul>

 *     <li> The {@link SocketPermission} to connect to an LDAP server.

 *     <li> The {@link AuthPermission} to modify the set of {@link Principal}s

 *          associated with a {@link Subject}.

 *     </ul>

 *     <p>

 *     For example, the following security policy grants an application in the

 *     user's current directory all the permissions required by this module:

 *     <pre>

 *

 *     grant codebase "file:${user.dir}/" {

 *         permission java.net.SocketPermission "*:389", "connect";

 *         permission java.net.SocketPermission "*:636", "connect";

 *         permission javax.security.auth.AuthPermission "modifyPrincipals";

 *     };

 *     </pre>

 * </dd>

 * </dl>

 *

 * @since 1.6

 */

public class LdapLoginModule implements LoginModule {

    // Keys to retrieve the stored username and password

    private static final String USERNAME_KEY = "javax.security.auth.login.name";

    private static final String PASSWORD_KEY =

        "javax.security.auth.login.password";

    // Option names

    private static final String USER_PROVIDER = "userProvider";

    private static final String USER_FILTER = "userFilter";

    private static final String AUTHC_IDENTITY = "authIdentity";

    private static final String AUTHZ_IDENTITY = "authzIdentity";

    // Used for the username token replacement

    private static final String USERNAME_TOKEN = "{USERNAME}";

    private static final Pattern USERNAME_PATTERN =

        Pattern.compile("\\{USERNAME\\}");

    // Configurable options

    private String userProvider;

    private String userFilter;

    private String authcIdentity;

    private String authzIdentity;

    private String authzIdentityAttr = null;

    private boolean useSSL = true;

    private boolean authFirst = false;

    private boolean authOnly = false;

    private boolean useFirstPass = false;

    private boolean tryFirstPass = false;

    private boolean storePass = false;

    private boolean clearPass = false;

    private boolean debug = false;

    // Authentication status

    private boolean succeeded = false;

    private boolean commitSucceeded = false;

    // Supplied username and password

    private String username;

    private char[] password;

    // User's identities

    private LdapPrincipal ldapPrincipal;

    private UserPrincipal userPrincipal;

    private UserPrincipal authzPrincipal;

    // Initial state

    private Subject subject;

    private CallbackHandler callbackHandler;

    private Map<String, Object> sharedState;

    private Map<String, ?> options;

    private LdapContext ctx;

    private Matcher identityMatcher = null;

    private Matcher filterMatcher = null;

    private Hashtable<String, Object> ldapEnvironment;

    private SearchControls constraints = null;

    /**

     * Initialize this {@code LoginModule}.

     *

     * @param subject the {@code Subject} to be authenticated.

     * @param callbackHandler a {@code CallbackHandler} to acquire the

     *                  username and password.

     * @param sharedState shared {@code LoginModule} state.

     * @param options options specified in the login

     *                  {@code Configuration} for this particular

     *                  {@code LoginModule}.

     */

    // Unchecked warning from (Map<String, Object>)sharedState is safe

    // since javax.security.auth.login.LoginContext passes a raw HashMap.

    @SuppressWarnings("unchecked")

    public void initialize(Subject subject, CallbackHandler callbackHandler,

                        Map<String, ?> sharedState, Map<String, ?> options) {

        this.subject = subject;

        this.callbackHandler = callbackHandler;

        this.sharedState = (Map<String, Object>)sharedState;

        this.options = options;

        ldapEnvironment = new Hashtable<String, Object>(9);

        ldapEnvironment.put(Context.INITIAL_CONTEXT_FACTORY,

            "com.sun.jndi.ldap.LdapCtxFactory");

        // Add any JNDI properties to the environment

        for (String key : options.keySet()) {

            if (key.indexOf('.') > -1) {

                ldapEnvironment.put(key, options.get(key));

            }

        }

        // initialize any configured options

        userProvider = (String)options.get(USER_PROVIDER);

        if (userProvider != null) {

            ldapEnvironment.put(Context.PROVIDER_URL, userProvider);

        }

        authcIdentity = (String)options.get(AUTHC_IDENTITY);

        if (authcIdentity != null &&

            (authcIdentity.indexOf(USERNAME_TOKEN) != -1)) {

            identityMatcher = USERNAME_PATTERN.matcher(authcIdentity);

        }

        userFilter = (String)options.get(USER_FILTER);

        if (userFilter != null) {

            if (userFilter.indexOf(USERNAME_TOKEN) != -1) {

                filterMatcher = USERNAME_PATTERN.matcher(userFilter);

            }

            constraints = new SearchControls();

            constraints.setSearchScope(SearchControls.SUBTREE_SCOPE);

            constraints.setReturningAttributes(new String[0]); //return no attrs

        }

        authzIdentity = (String)options.get(AUTHZ_IDENTITY);

        if (authzIdentity != null &&

            authzIdentity.startsWith("{") && authzIdentity.endsWith("}")) {

            if (constraints != null) {

                authzIdentityAttr =

                    authzIdentity.substring(1, authzIdentity.length() - 1);

                constraints.setReturningAttributes(

                    new String[]{authzIdentityAttr});

            }

            authzIdentity = null; // set later, from the specified attribute

        }

        // determine mode

        if (authcIdentity != null) {

            if (userFilter != null) {

                authFirst = true; // authentication-first mode

            } else {

                authOnly = true; // authentication-only mode

            }

        }

        if ("false".equalsIgnoreCase((String)options.get("useSSL"))) {

            useSSL = false;

            ldapEnvironment.remove(Context.SECURITY_PROTOCOL);

        } else {

            ldapEnvironment.put(Context.SECURITY_PROTOCOL, "ssl");

        }

        tryFirstPass =

                "true".equalsIgnoreCase((String)options.get("tryFirstPass"));

        useFirstPass =

                "true".equalsIgnoreCase((String)options.get("useFirstPass"));

        storePass = "true".equalsIgnoreCase((String)options.get("storePass"));

        clearPass = "true".equalsIgnoreCase((String)options.get("clearPass"));

        debug = "true".equalsIgnoreCase((String)options.get("debug"));

        if (debug) {

            if (authFirst) {

                System.out.println("\t\t[LdapLoginModule] " +

                    "authentication-first mode; " +

                    (useSSL ? "SSL enabled" : "SSL disabled"));

            } else if (authOnly) {

                System.out.println("\t\t[LdapLoginModule] " +

                    "authentication-only mode; " +

                    (useSSL ? "SSL enabled" : "SSL disabled"));

            } else {

                System.out.println("\t\t[LdapLoginModule] " +

                    "search-first mode; " +

                    (useSSL ? "SSL enabled" : "SSL disabled"));

            }

        }

    }

    /**

     * Begin user authentication.

     *

     * <p> Acquire the user's credentials and verify them against the

     * specified LDAP directory.

     *

     * @return true always, since this {@code LoginModule}

     *          should not be ignored.

     * @exception FailedLoginException if the authentication fails.

     * @exception LoginException if this {@code LoginModule}

     *          is unable to perform the authentication.

     */

    public boolean login() throws LoginException {

        if (userProvider == null) {

            throw new LoginException

                ("Unable to locate the LDAP directory service");

        }

        if (debug) {

            System.out.println("\t\t[LdapLoginModule] user provider: " +

                userProvider);

        }

        // attempt the authentication

        if (tryFirstPass) {

            try {

                // attempt the authentication by getting the

                // username and password from shared state

                attemptAuthentication(true);

                // authentication succeeded

                succeeded = true;

                if (debug) {

                    System.out.println("\t\t[LdapLoginModule] " +

                                "tryFirstPass succeeded");

                }

                return true;

            } catch (LoginException le) {

                // authentication failed -- try again below by prompting

                cleanState();

                if (debug) {

                    System.out.println("\t\t[LdapLoginModule] " +

                                "tryFirstPass failed: " + le.toString());

                }

            }