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package com.sun.security.sasl.gsskerb;
import java.io.IOException;
import java.util.Map;
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.
(RFC 2222,
draft-ietf-cat-sasl-gssapi-04.txt).
It uses the Java Bindings for GSSAPI
(RFC 2853) 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 GSSCredential used for delegated authentication. Author: Rosanna Lee
/**
* 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.
/**
* 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<String, ?> 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.
Params: - challengeData – A non-null byte array containing the
challenge data from the server.
Returns: A non-null byte array containing the response to be
sent to the server.
/**
* 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}",
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[] {recvMaxBufSize,
srvMaxBufSize,
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[]{selectedQop,
Boolean.valueOf(privacy),
Boolean.valueOf(integrity)});
}
if (privacy || integrity) {
// Last paragraph of RFC 4752 3.1: size ... MUST be 0 if the
// client does not support any security layer
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);
}
}
}