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.
* When this property of entry is set, and useTicketCache
* is set to true, only TGT belonging to this principal is used.
*
*
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 ticket * cache in the following locations: * 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 the above location, or if we are on a * 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. * For Windows, if a ticket cannot be retrieved from the file ticket cache, * it will use Local Security Authority (LSA) API to get the TGT. **
- *
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, the keytab, * or through shared state.(Default is false) * If set to true, credential must be obtained through cache, keytab, * or shared state. Otherwise, authentication will fail.
**
- *
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
*keytab* is not set then * the module will locate the keytab from the * Kerberos configuration file. * If it is not specified in the Kerberos configuration file * then it will look for the 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. **
If the principal system property or key is already provided, the value of * "javax.security.auth.login.name" in the shared state is ignored. *
When multiple mechanisms to retrieve a ticket or key is provided, the * preference order looks like this: *
Note that if any step fails, it will fallback to the next step.
* There's only one exception, it the shared state step fails and
* useFirstPass=true, no user prompt is made.
*
Examples of some configuration values for Krb5LoginModule in * JAAS config file and the results are: *
doNotPrompt=true;
*
This is an illegal combination since none of useTicketCache,
* useKeyTab, useFirstPass and tryFirstPass
* is 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, or from the shared state. 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. *
* useTicketCache=true
* ticketCache=<file name>;
* useKeyTab = true
* keyTab=<file name> storeKey=true
* principal= <principal name>
*
* 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, or the TGT's client name does not match the principal
* name, Java will use a secret key to obtain the TGT using the authentication
* exchange and added to the Subject's private credentials.
* This secret key will be first retrieved from the keytab. If the key
* is not available, the user will be prompted for the password. In either
* case, the key derived from the password will be added to the
* Subject's private credentials set.
*
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);
}
/*
* Before dynamic KeyTab support (6894072), here we check if
* the keytab contains keys for the principal. If no, keytab
* will not be used and password is prompted for.
*
* After 6894072, we normally don't check it, and expect the
* keys can be populated until a real connection is made. The
* check is still done when isInitiator == true, where the keys
* will be used right now.
*
* Probably tricky relations:
*
* useKeyTab is config flag, but when it's true but the ktab
* does not contains keys for principal, we would use password
* and keep the flag unchanged (for reuse?). In this method,
* we use (ktab != null) to check whether keytab is used.
* After this method (and when storeKey == true), we use
* (encKeys == null) to check.
*/
if (useKeyTab) {
ktab = (keyTabName == null)
? KeyTab.getInstance()
: KeyTab.getInstance(new File(keyTabName));
if (isInitiator) {
if (Krb5Util.keysFromJavaxKeyTab(ktab, principal).length
== 0) {
ktab = null;
if (debug) {
System.out.println
("Key for the principal " +
principal +
" not available in " +
((keyTabName == null) ?
"default key tab" : keyTabName));
}
}
}
}
KrbAsReqBuilder builder;
if (ktab == null) {
promptForPass(getPasswdFromSharedState);
builder = new KrbAsReqBuilder(principal, password);
if (isInitiator) {
// XXX Even if isInitiator=false, it might be
// better to do an AS-REQ so that keys can be
// updated with PA info
cred = builder.action().getCreds();
}
if (storeKey) {
encKeys = builder.getKeys(isInitiator);
// When encKeys is empty, the login actually fails.
// For compatibility, exception is thrown in commit().
}
} else {
builder = new KrbAsReqBuilder(principal, ktab);
if (isInitiator) {
cred = builder.action().getCreds();
}
}
builder.destroy();
if (debug) {
System.out.println("principal is " + principal);
HexDumpEncoder hd = new HexDumpEncoder();
if (ktab != null) {
System.out.println("Will use keytab");
} else if (storeKey) {
for (int i = 0; i < encKeys.length; i++) {
System.out.println("EncryptionKey: keyType=" +
encKeys[i].getEType() +
" keyBytes (hex dump)=" +
hd.encodeBuffer(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
&& !tryFirstPass && !useFirstPass)
throw new LoginException
("Configuration Error"
+ " - either doNotPrompt should be "
+ " false or at least one of useTicketCache, "
+ " useKeyTab, tryFirstPass and useFirstPass"
+ " 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
&& !tryFirstPass && !useFirstPass)
throw new LoginException
("Configuration Error - either doNotPrompt should be set to "
+ " false or at least one of tryFirstPass, useFirstPass "
+ "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.
*
*