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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* accompanied this code).
*
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package com.sun.security.sasl.gsskerb;
import java.io.IOException;
import java.util.Map;
import java.util.logging.Logger;
import java.util.logging.Level;
import javax.security.sasl.*;
// JAAS
import javax.security.auth.callback.CallbackHandler;
// JGSS
import org.ietf.jgss.*;
/**
* Implements the GSSAPI SASL client mechanism for Kerberos V5.
* (<A HREF="http://www.ietf.org/rfc/rfc2222.txt">RFC 2222</A>,
* <a HREF="http://www.ietf.org/internet-drafts/draft-ietf-cat-sasl-gssapi-04.txt">draft-ietf-cat-sasl-gssapi-04.txt</a>).
* It uses the Java Bindings for GSSAPI
* (<A HREF="http://www.ietf.org/rfc/rfc2853.txt">RFC 2853</A>)
* for getting GSSAPI/Kerberos V5 support.
*
* The client/server interactions are:
* C0: bind (GSSAPI, initial response)
* S0: sasl-bind-in-progress, challenge 1 (output of accept_sec_context or [])
* C1: bind (GSSAPI, response 1 (output of init_sec_context or []))
* S1: sasl-bind-in-progress challenge 2 (security layer, server max recv size)
* C2: bind (GSSAPI, response 2 (security layer, client max recv size, authzid))
* S2: bind success response
*
* Expects the client's credentials to be supplied from the
* javax.security.sasl.credentials property or from the thread's Subject.
* Otherwise the underlying KRB5 mech will attempt to acquire Kerberos creds
* by logging into Kerberos (via default TextCallbackHandler).
* These creds will be used for exchange with server.
*
* Required callbacks: none.
*
* Environment properties that affect behavior of implementation:
*
* javax.security.sasl.qop
* - quality of protection; list of auth, auth-int, auth-conf; default is "auth"
* javax.security.sasl.maxbuf
* - max receive buffer size; default is 65536
* javax.security.sasl.sendmaxbuffer
* - max send buffer size; default is 65536; (min with server max recv size)
*
* javax.security.sasl.server.authentication
* - "true" means require mutual authentication; default is "false"
*
* javax.security.sasl.credentials
* - an {@link org.ietf.jgss.GSSCredential} used for delegated authentication.
*
* @author Rosanna Lee
*/
final class GssKrb5Client extends GssKrb5Base implements SaslClient {
// ---------------- Constants -----------------
private static final String MY_CLASS_NAME = GssKrb5Client.class.getName();
private boolean finalHandshake = false;
private boolean mutual = false; // default false
private byte[] authzID;
/**
* Creates a SASL mechanism with client credentials that it needs
* to participate in GSS-API/Kerberos v5 authentication exchange
* with the server.
*/
GssKrb5Client(String authzID, String protocol, String serverName,
Map props, CallbackHandler cbh) throws SaslException {
super(props, MY_CLASS_NAME);
String service = protocol + "@" + serverName;
logger.log(Level.FINE, "KRB5CLNT01:Requesting service name: {0}",
service);
try {
GSSManager mgr = GSSManager.getInstance();
// Create the name for the requested service entity for Krb5 mech
GSSName acceptorName = mgr.createName(service,
GSSName.NT_HOSTBASED_SERVICE, KRB5_OID);
// Parse properties to check for supplied credentials
GSSCredential credentials = null;
if (props != null) {
Object prop = props.get(Sasl.CREDENTIALS);
if (prop != null && prop instanceof GSSCredential) {
credentials = (GSSCredential) prop;
logger.log(Level.FINE,
"KRB5CLNT01:Using the credentials supplied in " +
"javax.security.sasl.credentials");
}
}
// Create a context using credentials for Krb5 mech
secCtx = mgr.createContext(acceptorName,
KRB5_OID, /* mechanism */
credentials, /* credentials */
GSSContext.INDEFINITE_LIFETIME);
// Request credential delegation when credentials have been supplied
if (credentials != null) {
secCtx.requestCredDeleg(true);
}
// Parse properties to set desired context options
if (props != null) {
// Mutual authentication
String prop = (String)props.get(Sasl.SERVER_AUTH);
if (prop != null) {
mutual = "true".equalsIgnoreCase(prop);
}
}
secCtx.requestMutualAuth(mutual);
// Always specify potential need for integrity and confidentiality
// Decision will be made during final handshake
secCtx.requestConf(true);
secCtx.requestInteg(true);
} catch (GSSException e) {
throw new SaslException("Failure to initialize security context", e);
}
if (authzID != null && authzID.length() > 0) {
try {
this.authzID = authzID.getBytes("UTF8");
} catch (IOException e) {
throw new SaslException("Cannot encode authorization ID", e);
}
}
}
public boolean hasInitialResponse() {
return true;
}
/**
* Processes the challenge data.
*
* The server sends a challenge data using which the client must
* process using GSS_Init_sec_context.
* As per RFC 2222, when GSS_S_COMPLETE is returned, we do
* an extra handshake to determine the negotiated security protection
* and buffer sizes.
*
* @param challengeData A non-null byte array containing the
* challenge data from the server.
* @return A non-null byte array containing the response to be
* sent to the server.
*/
public byte[] evaluateChallenge(byte[] challengeData) throws SaslException {
if (completed) {
throw new IllegalStateException(
"GSSAPI authentication already complete");
}
if (finalHandshake) {
return doFinalHandshake(challengeData);
} else {
// Security context not established yet; continue with init
try {
byte[] gssOutToken = secCtx.initSecContext(challengeData,
0, challengeData.length);
if (logger.isLoggable(Level.FINER)) {
traceOutput(MY_CLASS_NAME, "evaluteChallenge",
"KRB5CLNT02:Challenge: [raw]", challengeData);
traceOutput(MY_CLASS_NAME, "evaluateChallenge",
"KRB5CLNT03:Response: [after initSecCtx]", gssOutToken);
}
if (secCtx.isEstablished()) {
finalHandshake = true;
if (gssOutToken == null) {
// RFC 2222 7.2.1: Client responds with no data
return EMPTY;
}
}
return gssOutToken;
} catch (GSSException e) {
throw new SaslException("GSS initiate failed", e);
}
}
}
private byte[] doFinalHandshake(byte[] challengeData) throws SaslException {
try {
// Security context already established. challengeData
// should contain security layers and server's maximum buffer size
if (logger.isLoggable(Level.FINER)) {
traceOutput(MY_CLASS_NAME, "doFinalHandshake",
"KRB5CLNT04:Challenge [raw]:", challengeData);
}
if (challengeData.length == 0) {
// Received S0, should return []
return EMPTY;
}
// Received S1 (security layer, server max recv size)
byte[] gssOutToken = secCtx.unwrap(challengeData, 0,
challengeData.length, new MessageProp(0, false));
// First octet is a bit-mask specifying the protections
// supported by the server
if (logger.isLoggable(Level.FINE)) {
if (logger.isLoggable(Level.FINER)) {
traceOutput(MY_CLASS_NAME, "doFinalHandshake",
"KRB5CLNT05:Challenge [unwrapped]:", gssOutToken);
}
logger.log(Level.FINE, "KRB5CLNT06:Server protections: {0}",
new Byte(gssOutToken[0]));
}
// Client selects preferred protection
// qop is ordered list of qop values
byte selectedQop = findPreferredMask(gssOutToken[0], qop);
if (selectedQop == 0) {
throw new SaslException(
"No common protection layer between client and server");
}
if ((selectedQop&PRIVACY_PROTECTION) != 0) {
privacy = true;
integrity = true;
} else if ((selectedQop&INTEGRITY_ONLY_PROTECTION) != 0) {
integrity = true;
}
// 2nd-4th octets specifies maximum buffer size expected by
// server (in network byte order)
int srvMaxBufSize = networkByteOrderToInt(gssOutToken, 1, 3);
// Determine the max send buffer size based on what the
// server is able to receive and our specified max
sendMaxBufSize = (sendMaxBufSize == 0) ? srvMaxBufSize :
Math.min(sendMaxBufSize, srvMaxBufSize);
// Update context to limit size of returned buffer
rawSendSize = secCtx.getWrapSizeLimit(JGSS_QOP, privacy,
sendMaxBufSize);
if (logger.isLoggable(Level.FINE)) {
logger.log(Level.FINE,
"KRB5CLNT07:Client max recv size: {0}; server max recv size: {1}; rawSendSize: {2}",
new Object[] {new Integer(recvMaxBufSize),
new Integer(srvMaxBufSize),
new Integer(rawSendSize)});
}
// Construct negotiated security layers and client's max
// receive buffer size and authzID
int len = 4;
if (authzID != null) {
len += authzID.length;
}
byte[] gssInToken = new byte[len];
gssInToken[0] = selectedQop;
if (logger.isLoggable(Level.FINE)) {
logger.log(Level.FINE,
"KRB5CLNT08:Selected protection: {0}; privacy: {1}; integrity: {2}",
new Object[]{new Byte(selectedQop),
Boolean.valueOf(privacy),
Boolean.valueOf(integrity)});
}
intToNetworkByteOrder(recvMaxBufSize, gssInToken, 1, 3);
if (authzID != null) {
// copy authorization id
System.arraycopy(authzID, 0, gssInToken, 4, authzID.length);
logger.log(Level.FINE, "KRB5CLNT09:Authzid: {0}", authzID);
}
if (logger.isLoggable(Level.FINER)) {
traceOutput(MY_CLASS_NAME, "doFinalHandshake",
"KRB5CLNT10:Response [raw]", gssInToken);
}
gssOutToken = secCtx.wrap(gssInToken,
0, gssInToken.length,
new MessageProp(0 /* qop */, false /* privacy */));
if (logger.isLoggable(Level.FINER)) {
traceOutput(MY_CLASS_NAME, "doFinalHandshake",
"KRB5CLNT11:Response [after wrap]", gssOutToken);
}
completed = true; // server authenticated
return gssOutToken;
} catch (GSSException e) {
throw new SaslException("Final handshake failed", e);
}
}
}