This LoginModule authenticates users using
+ * Kerberos protocols.
+ *
+ *
The configuration entry for Krb5LoginModule has
+ * several options that control the authentication process and
+ * additions to the Subject's private credential
+ * set. Irrespective of these options, the Subject's
+ * principal set and private credentials set are updated only when
+ * commit is called.
+ * When commit is called, the KerberosPrincipal
+ * is added to the Subject's
+ * principal set and KerberosTicket is
+ * added to the Subject's private credentials.
+ *
+ *
If the configuration entry for KerberosLoginModule
+ * has the option storeKey set to true, then
+ * KerberosKey will also be added to the
+ * subject's private credentials. KerberosKey, the principal's
+ * key will be either obtained from the keytab or
+ * derived from user's password.
+ *
+ *
This LoginModule recognizes the doNotPrompt
+ * option. If set to true the user will not be prompted for the password.
+ *
+ *
The user can specify the location of the ticket cache by using
+ * the option ticketCache in the configuration entry.
+ *
+ *
The user can specify the keytab location by using
+ * the option keyTab
+ * in the configuration entry.
+ *
+ *
The principal name can be specified in the configuration entry
+ * by using the option principal. The principal name
+ * can either be a simple user name or a service name such as
+ * host/mission.eng.sun.com. The principal can also
+ * be set using the system property sun.security.krb5.principal.
+ * This property is checked during login. If this property is not set, then
+ * the principal name from the configuration is used. In the
+ * case where the principal property is not set and the principal
+ * entry also does not exist, the user is prompted for the name.
+ *
+ *
The following is a list of configuration options supported
+ * for Krb5LoginModule:
+ *
- + *
refreshKrb5Config:- Set this to true, if you want the configuration + * to be refreshed before the
+ *loginmethod is called.+ *
- + *
useTicketCache:- Set this to true, if you want the + * TGT to be obtained + * from the ticket cache. Set this option + * to false if you do not want this module to use the ticket cache. + * (Default is False). + * This module will + * search for the tickect + * cache in the following locations: + * For Windows 2000, it will use Local Security Authority (LSA) API + * to get the TGT. On Solaris and Linux + * it will look for the ticket cache in /tmp/krb5cc_
uid+ * where the uid is numeric user + * identifier. If the ticket cache is + * not available in either of the above locations, or if we are on a + * different Windows platform, it will look for the cache as + * {user.home}{file.separator}krb5cc_{user.name}. + * You can override the ticket cache location by using + *ticketCache+ *+ *
- + *
ticketCache:- Set this to the name of the ticket + * cache that contains user's TGT. + * If this is set,
+ *useTicketCache+ * must also be set to true; Otherwise a configuration error will + * be returned.+ *
- + *
renewTGT:- Set this to true, if you want to renew + * the TGT. If this is set,
+ *useTicketCachemust also be + * set to true; otherwise a configuration error will be returned.+ *
- + *
doNotPrompt:- Set this to true if you do not want to be + * prompted for the password + * if credentials can + * not be obtained from the cache or keytab.(Default is false) + * If set to true authentication will fail if credentials can + * not be obtained from the cache or keytab.
+ *+ *
- + *
useKeyTab:- Set this to true if you + * want the module to get the principal's key from the + * the keytab.(default value is False) + * If
+ * If it is not specifed in the Kerberos configuration file + * then it will look for the file + *keyatb+ * is not set then + * the module will locate the keytab from the + * Kerberos configuration file.{user.home}{file.separator}krb5.keytab. + *+ *
- + *
keyTab:- Set this to the file name of the + * keytab to get principal's secret key.
+ *+ *
- + *
storeKey:- Set this to true to if you want the + * principal's key to be stored in the Subject's private credentials.
+ *+ *
- + *
principal:- The name of the principal that should + * be used. The principal can be a simple username such as + * "
+ *testuser" or a service name such as + * "host/testhost.eng.sun.com". You can use the + *principaloption to set the principal when there are + * credentials for multiple principals in the + *keyTabor when you want a specific ticket cache only. + * The principal can also be set using the system property + *sun.security.krb5.principal. In addition, if this + * system property is defined, then it will be used. If this property + * is not set, then the principal name from the configuration will be + * used.+ *
- + *
isInitiator:- Set this to true, if initiator. Set this to false, if acceptor only. + * (Default is true). + * Note: Do not set this value to false for initiators.
+ *
This LoginModule also recognizes the following additional
+ * Configuration
+ * options that enable you to share username and passwords across different
+ * authentication modules:
+ *
+ *
+ * useFirstPass if, true, this LoginModule 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.
+ *
+ * tryFirstPass if, true, this LoginModule retrieves the
+ * 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
+ * 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
+ *
+ * storePass if, true, this LoginModule stores the username and
+ * password obtained from the CallbackHandler in the
+ * modules 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.
+ *
+ * clearPass if, true, this LoginModule clears the
+ * username and password stored in the module's shared
+ * state after both phases of authentication
+ * (login and commit) have completed.
+ *
+ * Examples of some configuration values for Krb5LoginModule in + * JAAS config file and the results are: + *
doNotPrompt=true;
+ *
This is an illegal combination since useTicketCache
+ * is not set and the user can not be prompted for the password.
+ *
ticketCache = < filename >;
+ *
This is an illegal combination since useTicketCache
+ * is not set to true and the ticketCache is set. A configuration error
+ * will occur.
+ *
renewTGT=true;
+ *
This is an illegal combination since useTicketCache is
+ * not set to true and renewTGT is set. A configuration error will occur.
+ *
storeKey=true
+ * useTicketCache = true
+ * doNotPrompt=true;;
+ *
This is an illegal combination since storeKey is set to
+ * true but the key can not be obtained either by prompting the user or from
+ * the keytab.A configuration error will occur.
+ *
keyTab = < filename > doNotPrompt=true ;
+ *
This is an illegal combination since useKeyTab is not set to true and + * the keyTab is set. A configuration error will occur. + *
debug=true
+ *
Prompt the user for the principal name and the password.
+ * Use the authentication exchange to get TGT from the KDC and
+ * populate the Subject with the principal and TGT.
+ * Output debug messages.
+ *
useTicketCache = true doNotPrompt=true;
+ *
Check the default cache for TGT and populate the Subject
+ * with the principal and TGT. If the TGT is not available,
+ * do not prompt the user, instead fail the authentication.
+ *
principal=< name >useTicketCache = true
+ * doNotPrompt=true;
+ *
Get the TGT from the default cache for the principal and populate the + * Subject's principal and private creds set. If ticket cache is + * not available or does not contain the principal's TGT + * authentication will fail. + *
useTicketCache = true
+ * ticketCache=< file name >useKeyTab = true
+ * keyTab=< keytab filename >
+ * principal = < principal name >
+ * doNotPrompt=true;
+ *
Search the cache for the principal's TGT. If it is not available + * use the key in the keytab to perform authentication exchange with the + * KDC and acquire the TGT. + * The Subject will be populated with the principal and the TGT. + * If the key is not available or valid then authentication will fail. + *
useTicketCache = true
+ * ticketCache=< file name >
+ *
The TGT will be obtained from the cache specified. + * The Kerberos principal name used will be the principal name in + * the Ticket cache. If the TGT is not available in the + * ticket cache the user will be prompted for the principal name + * and the password. The TGT will be obtained using the authentication + * exchange with the KDC. + * The Subject will be populated with the TGT. + *
useKeyTab = true
+ * keyTab=< keytab filename >
+ * principal= < principal name >
+ * storeKey=true;
+ *
The key for the principal will be retrieved from the keytab. + * If the key is not available in the keytab the user will be prompted + * for the principal's password. The Subject will be populated + * with the principal's key either from the keytab or derived from the + * password entered. + *
useKeyTab = true
+ * keyTab=< keytabname >
+ * storeKey=true
+ * doNotPrompt=true;
+ *
The user will be prompted for the service principal name. + * If the principal's + * longterm key is available in the keytab , it will be added to the + * Subject's private credentials. An authentication exchange will be + * attempted with the principal name and the key from the Keytab. + * If successful the TGT will be added to the + * Subject's private credentials set. Otherwise the authentication will + * fail. + *
useKeyTab = true
+ * keyTab=< file name > storeKey=true
+ * principal= < principal name >
+ * useTicketCache=true
+ * ticketCache=< file name >;
+ *
The principal's key will be retrieved from the keytab and added
+ * to the Subject's private credentials. If the key
+ * is not available, the
+ * user will be prompted for the password; the key derived from the password
+ * will be added to the Subject's private credentials set. The
+ * client's TGT will be retrieved from the ticket cache and added to the
+ * Subject's private credentials. If the TGT is not available
+ * in the ticket cache, it will be obtained using the authentication
+ * exchange and added to the Subject's private credentials.
+ *
isInitiator = false
+ *
Configured to act as acceptor only, credentials are not acquired + * via AS exchange. For acceptors only, set this value to false. + * For initiators, do not set this value to false. + *
isInitiator = true
+ *
Configured to act as initiator, credentials are acquired
+ * via AS exchange. For initiators, set this value to true, or leave this
+ * option unset, in which case default value (true) will be used.
+ *
+ * @author Ram Marti
+ */
+
+public class Krb5LoginModule implements LoginModule {
+
+ // initial state
+ private Subject subject;
+ private CallbackHandler callbackHandler;
+ private Map sharedState;
+ private Map
+ * @param subject the
+ *
+ * @param callbackHandler a
+ *
+ * @param sharedState shared
+ *
+ * @param options options specified in the login
+ *
+ *
+ * @return true in all cases since this
+ *
+ * @exception LoginException if this This method is called if the LoginContext's
+ * overall authentication succeeded
+ * (the relevant REQUIRED, REQUISITE, SUFFICIENT and OPTIONAL
+ * LoginModules succeeded).
+ *
+ * If this LoginModule's own authentication attempt
+ * succeeded (checked by retrieving the private state saved by the
+ *
+ *
+ * @exception LoginException if the commit fails.
+ *
+ * @return true if this LoginModule's own login and commit
+ * attempts succeeded, or false otherwise.
+ */
+
+ public boolean commit() throws LoginException {
+
+ /*
+ * Let us add the Krb5 Creds to the Subject's
+ * private credentials. The credentials are of type
+ * KerberosKey or KerberosTicket
+ */
+ if (succeeded == false) {
+ return false;
+ } else {
+
+ if (isInitiator && (cred == null)) {
+ succeeded = false;
+ throw new LoginException("Null Client Credential");
+ }
+
+ if (subject.isReadOnly()) {
+ cleanKerberosCred();
+ throw new LoginException("Subject is Readonly");
+ }
+
+ /*
+ * Add the Principal (authenticated identity)
+ * to the Subject's principal set and
+ * add the credentials (TGT or Service key) to the
+ * Subject's private credentials
+ */
+
+ SetLoginModule.
+ *
+ * Subject to be authenticated. CallbackHandler for
+ * communication with the end user (prompting for
+ * usernames and passwords, for example). LoginModule state. Configuration for this particular
+ * LoginModule.
+ */
+
+ public void initialize(Subject subject,
+ CallbackHandler callbackHandler,
+ MapLoginModule
+ * should not be ignored.
+ *
+ * @exception FailedLoginException if the authentication fails. LoginModule
+ * is unable to perform the authentication.
+ */
+ public boolean login() throws LoginException {
+
+ int len;
+ validateConfiguration();
+ if (refreshKrb5Config) {
+ try {
+ if (debug) {
+ System.out.println("Refreshing Kerberos configuration");
+ }
+ sun.security.krb5.Config.refresh();
+ } catch (KrbException ke) {
+ LoginException le = new LoginException(ke.getMessage());
+ le.initCause(ke);
+ throw le;
+ }
+ }
+ String principalProperty = System.getProperty
+ ("sun.security.krb5.principal");
+ if (principalProperty != null) {
+ krb5PrincName = new StringBuffer(principalProperty);
+ } else {
+ if (princName != null) {
+ krb5PrincName = new StringBuffer(princName);
+ }
+ }
+
+ if (tryFirstPass) {
+ try {
+ attemptAuthentication(true);
+ if (debug)
+ System.out.println("\t\t[Krb5LoginModule] " +
+ "authentication succeeded");
+ succeeded = true;
+ cleanState();
+ return true;
+ } catch (LoginException le) {
+ // authentication failed -- try again below by prompting
+ cleanState();
+ if (debug) {
+ System.out.println("\t\t[Krb5LoginModule] " +
+ "tryFirstPass failed with:" +
+ le.getMessage());
+ }
+ }
+ } else if (useFirstPass) {
+ try {
+ attemptAuthentication(true);
+ succeeded = true;
+ cleanState();
+ return true;
+ } catch (LoginException e) {
+ // authentication failed -- clean out state
+ if (debug) {
+ System.out.println("\t\t[Krb5LoginModule] " +
+ "authentication failed \n" +
+ e.getMessage());
+ }
+ succeeded = false;
+ cleanState();
+ throw e;
+ }
+ }
+
+ // attempt the authentication by getting the username and pwd
+ // by prompting or configuration i.e. not from shared state
+
+ try {
+ attemptAuthentication(false);
+ succeeded = true;
+ cleanState();
+ return true;
+ } catch (LoginException e) {
+ // authentication failed -- clean out state
+ if (debug) {
+ System.out.println("\t\t[Krb5LoginModule] " +
+ "authentication failed \n" +
+ e.getMessage());
+ }
+ succeeded = false;
+ cleanState();
+ throw e;
+ }
+ }
+ /**
+ * process the configuration options
+ * Get the TGT either out of
+ * cache or from the KDC using the password entered
+ * Check the permission before getting the TGT
+ */
+
+ private void attemptAuthentication(boolean getPasswdFromSharedState)
+ throws LoginException {
+
+ /*
+ * Check the creds cache to see whether
+ * we have TGT for this client principal
+ */
+ if (krb5PrincName != null) {
+ try {
+ principal = new PrincipalName
+ (krb5PrincName.toString(),
+ PrincipalName.KRB_NT_PRINCIPAL);
+ } catch (KrbException e) {
+ LoginException le = new LoginException(e.getMessage());
+ le.initCause(e);
+ throw le;
+ }
+ }
+
+ try {
+ if (useTicketCache) {
+ // ticketCacheName == null implies the default cache
+ if (debug)
+ System.out.println("Acquire TGT from Cache");
+ cred = Credentials.acquireTGTFromCache
+ (principal, ticketCacheName);
+
+ if (cred != null) {
+ // check to renew credentials
+ if (!isCurrent(cred)) {
+ if (renewTGT) {
+ cred = renewCredentials(cred);
+ } else {
+ // credentials have expired
+ cred = null;
+ if (debug)
+ System.out.println("Credentials are" +
+ " no longer valid");
+ }
+ }
+ }
+
+ if (cred != null) {
+ // get the principal name from the ticket cache
+ if (principal == null) {
+ principal = cred.getClient();
+ }
+ }
+ if (debug) {
+ System.out.println("Principal is " + principal);
+ if (cred == null) {
+ System.out.println
+ ("null credentials from Ticket Cache");
+ }
+ }
+ }
+
+ // cred = null indicates that we didn't get the creds
+ // from the cache or useTicketCache was false
+
+ if (cred == null) {
+ // We need the principal name whether we use keytab
+ // or AS Exchange
+ if (principal == null) {
+ promptForName(getPasswdFromSharedState);
+ principal = new PrincipalName
+ (krb5PrincName.toString(),
+ PrincipalName.KRB_NT_PRINCIPAL);
+ }
+ if (useKeyTab) {
+ encKeys =
+ EncryptionKey.acquireSecretKeys(principal, keyTabName);
+
+ if (debug) {
+ if (encKeys != null)
+ System.out.println
+ ("principal's key obtained from the keytab");
+ else
+ System.out.println
+ ("Key for the principal " +
+ principal +
+ " not available in " +
+ ((keyTabName == null) ?
+ "default key tab" : keyTabName));
+ }
+
+ }
+ // We can't get the key from the keytab so prompt
+ if (encKeys == null) {
+ promptForPass(getPasswdFromSharedState);
+
+ encKeys = EncryptionKey.acquireSecretKeys(
+ password, principal.getSalt());
+
+ if (isInitiator) {
+ if (debug)
+ System.out.println("Acquire TGT using AS Exchange");
+ cred = Credentials.acquireTGT(principal,
+ encKeys, password);
+ // update keys after pre-auth
+ encKeys = EncryptionKey.acquireSecretKeys(password,
+ principal.getSalt());
+ }
+ } else {
+ if (isInitiator) {
+ if (debug)
+ System.out.println("Acquire TGT using AS Exchange");
+ cred = Credentials.acquireTGT(principal,
+ encKeys, password);
+ }
+ }
+
+ // Get the TGT using AS Exchange
+ if (debug) {
+ System.out.println("principal is " + principal);
+ HexDumpEncoder hd = new HexDumpEncoder();
+ for (int i = 0; i < encKeys.length; i++) {
+ System.out.println("EncryptionKey: keyType=" +
+ encKeys[i].getEType() + " keyBytes (hex dump)=" +
+ hd.encode(encKeys[i].getBytes()));
+ }
+ }
+
+ // we should hava a non-null cred
+ if (isInitiator && (cred == null)) {
+ throw new LoginException
+ ("TGT Can not be obtained from the KDC ");
+ }
+
+ }
+ } catch (KrbException e) {
+ LoginException le = new LoginException(e.getMessage());
+ le.initCause(e);
+ throw le;
+ } catch (IOException ioe) {
+ LoginException ie = new LoginException(ioe.getMessage());
+ ie.initCause(ioe);
+ throw ie;
+ }
+ }
+
+ private void promptForName(boolean getPasswdFromSharedState)
+ throws LoginException {
+ krb5PrincName = new StringBuffer("");
+ if (getPasswdFromSharedState) {
+ // use the name saved by the first module in the stack
+ username = (String)sharedState.get(NAME);
+ if (debug) {
+ System.out.println
+ ("username from shared state is " + username + "\n");
+ }
+ if (username == null) {
+ System.out.println
+ ("username from shared state is null\n");
+ throw new LoginException
+ ("Username can not be obtained from sharedstate ");
+ }
+ if (debug) {
+ System.out.println
+ ("username from shared state is " + username + "\n");
+ }
+ if (username != null && username.length() > 0) {
+ krb5PrincName.insert(0, username);
+ return;
+ }
+ }
+
+ if (doNotPrompt) {
+ throw new LoginException
+ ("Unable to obtain Princpal Name for authentication ");
+ } else {
+ if (callbackHandler == null)
+ throw new LoginException("No CallbackHandler "
+ + "available "
+ + "to garner authentication "
+ + "information from the user");
+ try {
+ String defUsername = System.getProperty("user.name");
+
+ Callback[] callbacks = new Callback[1];
+ MessageFormat form = new MessageFormat(
+ rb.getString(
+ "Kerberos username [[defUsername]]: "));
+ Object[] source = {defUsername};
+ callbacks[0] = new NameCallback(form.format(source));
+ callbackHandler.handle(callbacks);
+ username = ((NameCallback)callbacks[0]).getName();
+ if (username == null || username.length() == 0)
+ username = defUsername;
+ krb5PrincName.insert(0, username);
+
+ } catch (java.io.IOException ioe) {
+ throw new LoginException(ioe.getMessage());
+ } catch (UnsupportedCallbackException uce) {
+ throw new LoginException
+ (uce.getMessage()
+ +" not available to garner "
+ +" authentication information "
+ +" from the user");
+ }
+ }
+ }
+
+ private void promptForPass(boolean getPasswdFromSharedState)
+ throws LoginException {
+
+ if (getPasswdFromSharedState) {
+ // use the password saved by the first module in the stack
+ password = (char[])sharedState.get(PWD);
+ if (password == null) {
+ if (debug) {
+ System.out.println
+ ("Password from shared state is null");
+ }
+ throw new LoginException
+ ("Password can not be obtained from sharedstate ");
+ }
+ if (debug) {
+ System.out.println
+ ("password is " + new String(password));
+ }
+ return;
+ }
+ if (doNotPrompt) {
+ throw new LoginException
+ ("Unable to obtain password from user\n");
+ } else {
+ if (callbackHandler == null)
+ throw new LoginException("No CallbackHandler "
+ + "available "
+ + "to garner authentication "
+ + "information from the user");
+ try {
+ Callback[] callbacks = new Callback[1];
+ String userName = krb5PrincName.toString();
+ MessageFormat form = new MessageFormat(
+ rb.getString(
+ "Kerberos password for [username]: "));
+ Object[] source = {userName};
+ callbacks[0] = new PasswordCallback(
+ form.format(source),
+ false);
+ callbackHandler.handle(callbacks);
+ char[] tmpPassword = ((PasswordCallback)
+ callbacks[0]).getPassword();
+ if (tmpPassword == null) {
+ // treat a NULL password as an empty password
+ tmpPassword = new char[0];
+ }
+ password = new char[tmpPassword.length];
+ System.arraycopy(tmpPassword, 0,
+ password, 0, tmpPassword.length);
+ ((PasswordCallback)callbacks[0]).clearPassword();
+
+
+ // clear tmpPassword
+ for (int i = 0; i < tmpPassword.length; i++)
+ tmpPassword[i] = ' ';
+ tmpPassword = null;
+ if (debug) {
+ System.out.println("\t\t[Krb5LoginModule] " +
+ "user entered username: " +
+ krb5PrincName);
+ System.out.println();
+ }
+ } catch (java.io.IOException ioe) {
+ throw new LoginException(ioe.getMessage());
+ } catch (UnsupportedCallbackException uce) {
+ throw new LoginException(uce.getMessage()
+ +" not available to garner "
+ +" authentication information "
+ + "from the user");
+ }
+ }
+ }
+
+ private void validateConfiguration() throws LoginException {
+ if (doNotPrompt && !useTicketCache && !useKeyTab)
+ throw new LoginException
+ ("Configuration Error"
+ + " - either doNotPrompt should be "
+ + " false or useTicketCache/useKeyTab "
+ + " should be true");
+ if (ticketCacheName != null && !useTicketCache)
+ throw new LoginException
+ ("Configuration Error "
+ + " - useTicketCache should be set "
+ + "to true to use the ticket cache"
+ + ticketCacheName);
+ if (keyTabName != null & !useKeyTab)
+ throw new LoginException
+ ("Configuration Error - useKeyTab should be set to true "
+ + "to use the keytab" + keyTabName);
+ if (storeKey && doNotPrompt && !useKeyTab)
+ throw new LoginException
+ ("Configuration Error - either doNotPrompt "
+ + "should be set to false or "
+ + "useKeyTab must be set to true for storeKey option");
+ if (renewTGT && !useTicketCache)
+ throw new LoginException
+ ("Configuration Error"
+ + " - either useTicketCache should be "
+ + " true or renewTGT should be false");
+ }
+
+ private boolean isCurrent(Credentials creds)
+ {
+ Date endTime = creds.getEndTime();
+ if (endTime != null) {
+ return (System.currentTimeMillis() <= endTime.getTime());
+ }
+ return true;
+ }
+
+ private Credentials renewCredentials(Credentials creds)
+ {
+ Credentials lcreds;
+ try {
+ if (!creds.isRenewable())
+ throw new RefreshFailedException("This ticket" +
+ " is not renewable");
+ if (System.currentTimeMillis() > cred.getRenewTill().getTime())
+ throw new RefreshFailedException("This ticket is past "
+ + "its last renewal time.");
+ lcreds = creds.renew();
+ if (debug)
+ System.out.println("Renewed Kerberos Ticket");
+ } catch (Exception e) {
+ lcreds = null;
+ if (debug)
+ System.out.println("Ticket could not be renewed : "
+ + e.getMessage());
+ }
+ return lcreds;
+ }
+
+ /**
+ * login method), then this method associates a
+ * Krb5Principal
+ * with the Subject located in the
+ * LoginModule. It adds Kerberos Credentials to the
+ * the Subject's private credentials set. If this LoginModule's own
+ * authentication attempted failed, then this method removes
+ * any state that was originally saved.
+ *
+ *