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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.security.authentication.util;
import static org.apache.hadoop.util.PlatformName.IBM_JAVA;
import java.io.File;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
import java.nio.charset.IllegalCharsetNameException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.regex.Pattern;
import org.apache.directory.server.kerberos.shared.keytab.Keytab;
import org.apache.directory.server.kerberos.shared.keytab.KeytabEntry;
import org.ietf.jgss.GSSException;
import org.ietf.jgss.Oid;
import javax.security.auth.Subject;
import javax.security.auth.kerberos.KerberosTicket;
import javax.security.auth.kerberos.KeyTab;
public class KerberosUtil {
/* Return the Kerberos login module name */
public static String getKrb5LoginModuleName() {
return System.getProperty("java.vendor").contains("IBM")
? "com.ibm.security.auth.module.Krb5LoginModule"
: "com.sun.security.auth.module.Krb5LoginModule";
}
public static final Oid GSS_SPNEGO_MECH_OID =
getNumericOidInstance("1.3.6.1.5.5.2");
public static final Oid GSS_KRB5_MECH_OID =
getNumericOidInstance("1.2.840.113554.1.2.2");
public static final Oid NT_GSS_KRB5_PRINCIPAL_OID =
getNumericOidInstance("1.2.840.113554.1.2.2.1");
// numeric oids will never generate a GSSException for a malformed oid.
// use to initialize statics.
private static Oid getNumericOidInstance(String oidName) {
try {
return new Oid(oidName);
} catch (GSSException ex) {
throw new IllegalArgumentException(ex);
}
}
public static Oid getOidInstance(String oidName)
throws ClassNotFoundException, GSSException, NoSuchFieldException,
IllegalAccessException {
Class oidClass;
if (IBM_JAVA) {
if ("NT_GSS_KRB5_PRINCIPAL".equals(oidName)) {
// IBM JDK GSSUtil class does not have field for krb5 principal oid
return new Oid("1.2.840.113554.1.2.2.1");
}
oidClass = Class.forName("com.ibm.security.jgss.GSSUtil");
} else {
oidClass = Class.forName("sun.security.jgss.GSSUtil");
}
Field oidField = oidClass.getDeclaredField(oidName);
return (Oid)oidField.get(oidClass);
}
public static String getDefaultRealm()
throws ClassNotFoundException, NoSuchMethodException,
IllegalArgumentException, IllegalAccessException,
InvocationTargetException {
Object kerbConf;
Class classRef;
Method getInstanceMethod;
Method getDefaultRealmMethod;
if (System.getProperty("java.vendor").contains("IBM")) {
classRef = Class.forName("com.ibm.security.krb5.internal.Config");
} else {
classRef = Class.forName("sun.security.krb5.Config");
}
getInstanceMethod = classRef.getMethod("getInstance", new Class[0]);
kerbConf = getInstanceMethod.invoke(classRef, new Object[0]);
getDefaultRealmMethod = classRef.getDeclaredMethod("getDefaultRealm",
new Class[0]);
return (String)getDefaultRealmMethod.invoke(kerbConf, new Object[0]);
}
public static String getDefaultRealmProtected() {
String realmString = null;
try {
realmString = getDefaultRealm();
} catch (RuntimeException rte) {
//silently catch everything
} catch (Exception e) {
//silently return null
}
return realmString;
}
/*
* For a Service Host Principal specification, map the host's domain
* to kerberos realm, as specified by krb5.conf [domain_realm] mappings.
* Unfortunately the mapping routines are private to the security.krb5
* package, so have to construct a PrincipalName instance to derive the realm.
*
* Many things can go wrong with Kerberos configuration, and this is not
* the place to be throwing exceptions to help debug them. Nor do we choose
* to make potentially voluminous logs on every call to a communications API.
* So we simply swallow all exceptions from the underlying libraries and
* return null if we can't get a good value for the realmString.
*
* @param shortprinc A service principal name with host fqdn as instance, e.g.
* "HTTP/myhost.mydomain"
* @return String value of Kerberos realm, mapped from host fqdn
* May be default realm, or may be null.
*/
public static String getDomainRealm(String shortprinc) {
Class classRef;
Object principalName; //of type sun.security.krb5.PrincipalName or IBM equiv
String realmString = null;
try {
if (System.getProperty("java.vendor").contains("IBM")) {
classRef = Class.forName("com.ibm.security.krb5.PrincipalName");
} else {
classRef = Class.forName("sun.security.krb5.PrincipalName");
}
int tKrbNtSrvHst = classRef.getField("KRB_NT_SRV_HST").getInt(null);
principalName = classRef.getConstructor(String.class, int.class).
newInstance(shortprinc, tKrbNtSrvHst);
realmString = (String)classRef.getMethod("getRealmString", new Class[0]).
invoke(principalName, new Object[0]);
} catch (RuntimeException rte) {
//silently catch everything
} catch (Exception e) {
//silently return default realm (which may itself be null)
}
if (null == realmString || realmString.equals("")) {
return getDefaultRealmProtected();
} else {
return realmString;
}
}
/* Return fqdn of the current host */
static String getLocalHostName() throws UnknownHostException {
return InetAddress.getLocalHost().getCanonicalHostName();
}
/**
* Create Kerberos principal for a given service and hostname,
* inferring realm from the fqdn of the hostname. It converts
* hostname to lower case. If hostname is null or "0.0.0.0", it uses
* dynamically looked-up fqdn of the current host instead.
* If domain_realm mappings are inadequately specified, it will
* use default_realm, per usual Kerberos behavior.
* If default_realm also gives a null value, then a principal
* without realm will be returned, which by Kerberos definitions is
* just another way to specify default realm.
*
* @param service
* Service for which you want to generate the principal.
* @param hostname
* Fully-qualified domain name.
* @return Converted Kerberos principal name.
* @throws UnknownHostException
* If no IP address for the local host could be found.
*/
public static final String getServicePrincipal(String service,
String hostname)
throws UnknownHostException {
String fqdn = hostname;
String shortprinc = null;
String realmString = null;
if (null == fqdn || fqdn.equals("") || fqdn.equals("0.0.0.0")) {
fqdn = getLocalHostName();
}
// convert hostname to lowercase as kerberos does not work with hostnames
// with uppercase characters.
fqdn = fqdn.toLowerCase(Locale.ENGLISH);
shortprinc = service + "/" + fqdn;
// Obtain the realm name inferred from the domain of the host
realmString = getDomainRealm(shortprinc);
if (null == realmString || realmString.equals("")) {
return shortprinc;
} else {
return shortprinc + "@" + realmString;
}
}
/**
* Get all the unique principals present in the keytabfile.
*
* @param keytabFileName
* Name of the keytab file to be read.
* @return list of unique principals in the keytab.
* @throws IOException
* If keytab entries cannot be read from the file.
*/
static final String[] getPrincipalNames(String keytabFileName) throws IOException {
Keytab keytab = Keytab.read(new File(keytabFileName));
Set principals = new HashSet();
List entries = keytab.getEntries();
for (KeytabEntry entry: entries){
principals.add(entry.getPrincipalName().replace("\\", "/"));
}
return principals.toArray(new String[0]);
}
/**
* Get all the unique principals from keytabfile which matches a pattern.
*
* @param keytab Name of the keytab file to be read.
* @param pattern pattern to be matched.
* @return list of unique principals which matches the pattern.
* @throws IOException if cannot get the principal name
*/
public static final String[] getPrincipalNames(String keytab,
Pattern pattern) throws IOException {
String[] principals = getPrincipalNames(keytab);
if (principals.length != 0) {
List matchingPrincipals = new ArrayList();
for (String principal : principals) {
if (pattern.matcher(principal).matches()) {
matchingPrincipals.add(principal);
}
}
principals = matchingPrincipals.toArray(new String[0]);
}
return principals;
}
/**
* Check if the subject contains Kerberos keytab related objects.
* The Kerberos keytab object attached in subject has been changed
* from KerberosKey (JDK 7) to KeyTab (JDK 8)
*
*
* @param subject subject to be checked
* @return true if the subject contains Kerberos keytab
*/
public static boolean hasKerberosKeyTab(Subject subject) {
return !subject.getPrivateCredentials(KeyTab.class).isEmpty();
}
/**
* Check if the subject contains Kerberos ticket.
*
*
* @param subject subject to be checked
* @return true if the subject contains Kerberos ticket
*/
public static boolean hasKerberosTicket(Subject subject) {
return !subject.getPrivateCredentials(KerberosTicket.class).isEmpty();
}
/**
* Extract the TGS server principal from the given gssapi kerberos or spnego
* wrapped token.
* @param rawToken bytes of the gss token
* @return String of server principal
* @throws IllegalArgumentException if token is undecodable
*/
public static String getTokenServerName(byte[] rawToken) {
// subsequent comments include only relevant portions of the kerberos
// DER encoding that will be extracted.
DER token = new DER(rawToken);
// InitialContextToken ::= [APPLICATION 0] IMPLICIT SEQUENCE {
// mech OID
// mech-token (NegotiationToken or InnerContextToken)
// }
DER oid = token.next();
if (oid.equals(DER.SPNEGO_MECH_OID)) {
// NegotiationToken ::= CHOICE {
// neg-token-init[0] NegTokenInit
// }
// NegTokenInit ::= SEQUENCE {
// mech-token[2] InitialContextToken
// }
token = token.next().get(0xa0, 0x30, 0xa2, 0x04).next();
oid = token.next();
}
if (!oid.equals(DER.KRB5_MECH_OID)) {
throw new IllegalArgumentException("Malformed gss token");
}
// InnerContextToken ::= {
// token-id[1]
// AP-REQ
// }
if (token.next().getTag() != 1) {
throw new IllegalArgumentException("Not an AP-REQ token");
}
// AP-REQ ::= [APPLICATION 14] SEQUENCE {
// ticket[3] Ticket
// }
DER ticket = token.next().get(0x6e, 0x30, 0xa3, 0x61, 0x30);
// Ticket ::= [APPLICATION 1] SEQUENCE {
// realm[1] String
// sname[2] PrincipalName
// }
// PrincipalName ::= SEQUENCE {
// name-string[1] SEQUENCE OF String
// }
String realm = ticket.get(0xa1, 0x1b).getAsString();
DER names = ticket.get(0xa2, 0x30, 0xa1, 0x30);
StringBuilder sb = new StringBuilder();
while (names.hasNext()) {
if (sb.length() > 0) {
sb.append('/');
}
sb.append(names.next().getAsString());
}
return sb.append('@').append(realm).toString();
}
// basic ASN.1 DER decoder to traverse encoded byte arrays.
private static class DER implements Iterator {
static final DER SPNEGO_MECH_OID = getDER(GSS_SPNEGO_MECH_OID);
static final DER KRB5_MECH_OID = getDER(GSS_KRB5_MECH_OID);
private static DER getDER(Oid oid) {
try {
return new DER(oid.getDER());
} catch (GSSException ex) {
// won't happen. a proper OID is encodable.
throw new IllegalArgumentException(ex);
}
}
private final int tag;
private final ByteBuffer bb;
DER(byte[] buf) {
this(ByteBuffer.wrap(buf));
}
DER(ByteBuffer srcbb) {
tag = srcbb.get() & 0xff;
int length = readLength(srcbb);
bb = srcbb.slice();
bb.limit(length);
srcbb.position(srcbb.position() + length);
}
int getTag() {
return tag;
}
// standard ASN.1 encoding.
private static int readLength(ByteBuffer bb) {
int length = bb.get();
if ((length & (byte)0x80) != 0) {
int varlength = length & 0x7f;
length = 0;
for (int i=0; i < varlength; i++) {
length = (length << 8) | (bb.get() & 0xff);
}
}
return length;
}
DER choose(int subtag) {
while (hasNext()) {
DER der = next();
if (der.getTag() == subtag) {
return der;
}
}
return null;
}
DER get(int... tags) {
DER der = this;
for (int i=0; i < tags.length; i++) {
int expectedTag = tags[i];
// lookup for exact match, else scan if it's sequenced.
if (der.getTag() != expectedTag) {
der = der.hasNext() ? der.choose(expectedTag) : null;
}
if (der == null) {
StringBuilder sb = new StringBuilder("Tag not found:");
for (int ii=0; ii <= i; ii++) {
sb.append(" 0x").append(Integer.toHexString(tags[ii]));
}
throw new IllegalStateException(sb.toString());
}
}
return der;
}
String getAsString() {
try {
return new String(bb.array(), bb.arrayOffset() + bb.position(),
bb.remaining(), "UTF-8");
} catch (UnsupportedEncodingException e) {
throw new IllegalCharsetNameException("UTF-8"); // won't happen.
}
}
@Override
public int hashCode() {
return 31 * tag + bb.hashCode();
}
@Override
public boolean equals(Object o) {
return (o instanceof DER) &&
tag == ((DER)o).tag && bb.equals(((DER)o).bb);
}
@Override
public boolean hasNext() {
// it's a sequence or an embedded octet.
return ((tag & 0x30) != 0 || tag == 0x04) && bb.hasRemaining();
}
@Override
public DER next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
return new DER(bb);
}
@Override
public String toString() {
return "[tag=0x"+Integer.toHexString(tag)+" bb="+bb+"]";
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}
}
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