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package com.sun.security.sasl.gsskerb;

import javax.security.sasl.*;
import java.io.*;
import java.util.Map;
import java.util.logging.Level;

// JAAS
import javax.security.auth.callback.*;

// JGSS
import org.ietf.jgss.*;

Implements the GSSAPI SASL server mechanism for Kerberos V5. (RFC 2222, draft-ietf-cat-sasl-gssapi-00.txt). Expects thread's Subject to contain server's Kerberos credentials - If not, underlying KRB5 mech will attempt to acquire Kerberos creds by logging into Kerberos (via default TextCallbackHandler). - These creds will be used for exchange with client. Required callbacks: - AuthorizeCallback handler must verify that authid/authzids are allowed and set authorized ID to be the canonicalized authzid (if applicable). 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 client max recv size)
Author:Rosanna Lee
/** * Implements the GSSAPI SASL server 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-00.txt">draft-ietf-cat-sasl-gssapi-00.txt</a>). * * Expects thread's Subject to contain server's Kerberos credentials * - If not, underlying KRB5 mech will attempt to acquire Kerberos creds * by logging into Kerberos (via default TextCallbackHandler). * - These creds will be used for exchange with client. * * Required callbacks: * - AuthorizeCallback * handler must verify that authid/authzids are allowed and set * authorized ID to be the canonicalized authzid (if applicable). * * 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 client max recv size) * * @author Rosanna Lee */
final class GssKrb5Server extends GssKrb5Base implements SaslServer { private static final String MY_CLASS_NAME = GssKrb5Server.class.getName(); private int handshakeStage = 0; private String peer; private String me; private String authzid; private CallbackHandler cbh; // When serverName is null, the server will be unbound. We need to save and // check the protocol name after the context is established. This value // will be null if serverName is not null. private final String protocolSaved;
Creates a SASL mechanism with server credentials that it needs to participate in GSS-API/Kerberos v5 authentication exchange with the client.
/** * Creates a SASL mechanism with server credentials that it needs * to participate in GSS-API/Kerberos v5 authentication exchange * with the client. */
GssKrb5Server(String protocol, String serverName, Map<String, ?> props, CallbackHandler cbh) throws SaslException { super(props, MY_CLASS_NAME); this.cbh = cbh; String service; if (serverName == null) { protocolSaved = protocol; service = null; } else { protocolSaved = null; service = protocol + "@" + serverName; } logger.log(Level.FINE, "KRB5SRV01:Using service name: {0}", service); try { GSSManager mgr = GSSManager.getInstance(); // Create the name for the requested service entity for Krb5 mech GSSName serviceName = service == null ? null: mgr.createName(service, GSSName.NT_HOSTBASED_SERVICE, KRB5_OID); GSSCredential cred = mgr.createCredential(serviceName, GSSCredential.INDEFINITE_LIFETIME, KRB5_OID, GSSCredential.ACCEPT_ONLY); // Create a context using the server's credentials secCtx = mgr.createContext(cred); if ((allQop&INTEGRITY_ONLY_PROTECTION) != 0) { // Might need integrity secCtx.requestInteg(true); } if ((allQop&PRIVACY_PROTECTION) != 0) { // Might need privacy secCtx.requestConf(true); } } catch (GSSException e) { throw new SaslException("Failure to initialize security context", e); } logger.log(Level.FINE, "KRB5SRV02:Initialization complete"); }
Processes the response data. The client sends response data to which the server must process using GSS_accept_sec_context. As per RFC 2222, the GSS authenication completes (GSS_S_COMPLETE) we do an extra hand shake to determine the negotiated security protection and buffer sizes.
Params:
  • responseData – A non-null but possible empty byte array containing the response data from the client.
Returns:A non-null byte array containing the challenge to be sent to the client, or null when no more data is to be sent.
/** * Processes the response data. * * The client sends response data to which the server must * process using GSS_accept_sec_context. * As per RFC 2222, the GSS authenication completes (GSS_S_COMPLETE) * we do an extra hand shake to determine the negotiated security protection * and buffer sizes. * * @param responseData A non-null but possible empty byte array containing the * response data from the client. * @return A non-null byte array containing the challenge to be * sent to the client, or null when no more data is to be sent. */
public byte[] evaluateResponse(byte[] responseData) throws SaslException { if (completed) { throw new SaslException( "SASL authentication already complete"); } if (logger.isLoggable(Level.FINER)) { traceOutput(MY_CLASS_NAME, "evaluateResponse", "KRB5SRV03:Response [raw]:", responseData); } switch (handshakeStage) { case 1: return doHandshake1(responseData); case 2: return doHandshake2(responseData); default: // Security context not established yet; continue with accept try { byte[] gssOutToken = secCtx.acceptSecContext(responseData, 0, responseData.length); if (logger.isLoggable(Level.FINER)) { traceOutput(MY_CLASS_NAME, "evaluateResponse", "KRB5SRV04:Challenge: [after acceptSecCtx]", gssOutToken); } if (secCtx.isEstablished()) { handshakeStage = 1; peer = secCtx.getSrcName().toString(); me = secCtx.getTargName().toString(); logger.log(Level.FINE, "KRB5SRV05:Peer name is : {0}, my name is : {1}", new Object[]{peer, me}); // me might take the form of proto@host or proto/host if (protocolSaved != null && !protocolSaved.equalsIgnoreCase(me.split("[/@]")[0])) { throw new SaslException( "GSS context targ name protocol error: " + me); } if (gssOutToken == null) { return doHandshake1(EMPTY); } } return gssOutToken; } catch (GSSException e) { throw new SaslException("GSS initiate failed", e); } } } private byte[] doHandshake1(byte[] responseData) throws SaslException { try { // Security context already established. responseData // should contain no data if (responseData != null && responseData.length > 0) { throw new SaslException( "Handshake expecting no response data from server"); } // Construct 4 octets of data: // First octet contains bitmask specifying protections supported // 2nd-4th octets contains max receive buffer of server byte[] gssInToken = new byte[4]; gssInToken[0] = allQop; intToNetworkByteOrder(recvMaxBufSize, gssInToken, 1, 3); if (logger.isLoggable(Level.FINE)) { logger.log(Level.FINE, "KRB5SRV06:Supported protections: {0}; recv max buf size: {1}", new Object[]{allQop, recvMaxBufSize}); } handshakeStage = 2; // progress to next stage if (logger.isLoggable(Level.FINER)) { traceOutput(MY_CLASS_NAME, "doHandshake1", "KRB5SRV07:Challenge [raw]", gssInToken); } byte[] gssOutToken = secCtx.wrap(gssInToken, 0, gssInToken.length, new MessageProp(0 /* gop */, false /* privacy */)); if (logger.isLoggable(Level.FINER)) { traceOutput(MY_CLASS_NAME, "doHandshake1", "KRB5SRV08:Challenge [after wrap]", gssOutToken); } return gssOutToken; } catch (GSSException e) { throw new SaslException("Problem wrapping handshake1", e); } } private byte[] doHandshake2(byte[] responseData) throws SaslException { try { // Expecting 4 octets from client selected protection // and client's receive buffer size byte[] gssOutToken = secCtx.unwrap(responseData, 0, responseData.length, new MessageProp(0, false)); if (logger.isLoggable(Level.FINER)) { traceOutput(MY_CLASS_NAME, "doHandshake2", "KRB5SRV09:Response [after unwrap]", gssOutToken); } // First octet is a bit-mask specifying the selected protection byte selectedQop = gssOutToken[0]; if ((selectedQop&allQop) == 0) { throw new SaslException("Client selected unsupported protection: " + selectedQop); } 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 // client (in network byte order). This is the server's send // buffer maximum. int clntMaxBufSize = networkByteOrderToInt(gssOutToken, 1, 3); // Determine the max send buffer size based on what the // client is able to receive and our specified max sendMaxBufSize = (sendMaxBufSize == 0) ? clntMaxBufSize : Math.min(sendMaxBufSize, clntMaxBufSize); // Update context to limit size of returned buffer rawSendSize = secCtx.getWrapSizeLimit(JGSS_QOP, privacy, sendMaxBufSize); if (logger.isLoggable(Level.FINE)) { logger.log(Level.FINE, "KRB5SRV10:Selected protection: {0}; privacy: {1}; integrity: {2}", new Object[]{selectedQop, Boolean.valueOf(privacy), Boolean.valueOf(integrity)}); logger.log(Level.FINE, "KRB5SRV11:Client max recv size: {0}; server max send size: {1}; rawSendSize: {2}", new Object[] {clntMaxBufSize, sendMaxBufSize, rawSendSize}); } // Get authorization identity, if any if (gssOutToken.length > 4) { try { authzid = new String(gssOutToken, 4, gssOutToken.length - 4, "UTF-8"); } catch (UnsupportedEncodingException uee) { throw new SaslException ("Cannot decode authzid", uee); } } else { authzid = peer; } logger.log(Level.FINE, "KRB5SRV12:Authzid: {0}", authzid); AuthorizeCallback acb = new AuthorizeCallback(peer, authzid); // In Kerberos, realm is embedded in peer name cbh.handle(new Callback[] {acb}); if (acb.isAuthorized()) { authzid = acb.getAuthorizedID(); completed = true; } else { // Authorization failed throw new SaslException(peer + " is not authorized to connect as " + authzid); } return null; } catch (GSSException e) { throw new SaslException("Final handshake step failed", e); } catch (IOException e) { throw new SaslException("Problem with callback handler", e); } catch (UnsupportedCallbackException e) { throw new SaslException("Problem with callback handler", e); } } public String getAuthorizationID() { if (completed) { return authzid; } else { throw new IllegalStateException("Authentication incomplete"); } } public Object getNegotiatedProperty(String propName) { if (!completed) { throw new IllegalStateException("Authentication incomplete"); } Object result; switch (propName) { case Sasl.BOUND_SERVER_NAME: try { // me might take the form of proto@host or proto/host result = me.split("[/@]")[1]; } catch (Exception e) { result = null; } break; default: result = super.getNegotiatedProperty(propName); } return result; } }