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Commit 78e4eff7 authored by Dave Cridland's avatar Dave Cridland
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OF-405 : Perform proper path validation on certificate chains 

What this patch actually does is place existing certificates into a CertStore,
including those from its (untrusted) keystore, the trust store, and any from
the chain supplied by the peer, and then rebuild a chain back to a known trust
anchor (from the trust store).

This strategy will cope with unknown ICAs in chains, abbreviated chains, and so
on, and replaces attempts to specifically handle self-signed certificates.

That last said, there is an explicit shortcut to handle self-signed certificates
which are supplied as end-entity certificates. These are simply checked against
the trust store without any attempt to build a path.
parent 73b59106
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Showing with 155 additions and 31 deletions
src/java/org/jivesoftware/openfire/net/SASLAuthentication.java
View file @ 78e4eff7
......@@ -187,24 +187,18 @@ public class SASLAuthentication {
if (session instanceof IncomingServerSession) {
// Server connections don't follow the same rules as clients
if (session.isSecure()) {
boolean usingSelfSigned;
final Certificate[] chain = session.getConnection().getLocalCertificates();
if (chain == null || chain.length == 0) {
usingSelfSigned = true;
} else {
try {
usingSelfSigned = CertificateManager.isSelfSignedCertificate(SSLConfig.getKeyStore(), (X509Certificate) chain[0]);
} catch (KeyStoreException ex) {
Log.warn("Exception occurred while trying to determine whether local certificate is self-signed. Proceeding as if it is.", ex);
usingSelfSigned = true;
} catch (IOException ex) {
Log.warn("Exception occurred while trying to determine whether local certificate is self-signed. Proceeding as if it is.", ex);
usingSelfSigned = true;
}
boolean usingSelfSigned = true;
try {
X509Certificate trusted = CertificateManager.getEndEntityCertificate(session.getConnection().getPeerCertificates(), SSLConfig.getKeyStore(), SSLConfig.gets2sTrustStore());
usingSelfSigned = trusted == null;
} catch (IOException ex) {
Log.warn("Exception occurred while trying to determine whether remote certificate is trusted. Proceeding as if it is.", ex);
usingSelfSigned = true;
}
if (!usingSelfSigned) {
// Offer SASL EXTERNAL only if TLS has already been negotiated and we are not
// Offer SASL EXTERNAL only if TLS has already been negotiated and the peer is not
// using a self-signed certificate
sb.append("<mechanism>EXTERNAL</mechanism>");
}
......@@ -229,11 +223,21 @@ public class SASLAuthentication {
Element mechs = DocumentHelper.createElement(new QName("mechanisms",
new Namespace("", "urn:ietf:params:xml:ns:xmpp-sasl")));
if (session instanceof IncomingServerSession) {
// Server connections dont follow the same rules as clients
// Server connections don't follow the same rules as clients
if (session.isSecure()) {
// Offer SASL EXTERNAL only if TLS has already been negotiated
Element mechanism = mechs.addElement("mechanism");
mechanism.setText("EXTERNAL");
boolean usingSelfSigned = true;
try {
X509Certificate trusted = CertificateManager.getEndEntityCertificate(((LocalSession)session).getConnection().getPeerCertificates(), SSLConfig.getKeyStore(), SSLConfig.gets2sTrustStore());
usingSelfSigned = trusted == null;
} catch (IOException ex) {
Log.warn("Exception occurred while trying to determine whether remote certificate is trusted. Proceeding as if it is.", ex);
usingSelfSigned = true;
}
if (!usingSelfSigned) {
// Offer SASL EXTERNAL only if TLS has already been negotiated and the peer has a trusted cert.
Element mechanism = mechs.addElement("mechanism");
mechanism.setText("EXTERNAL");
}
}
}
else {
......@@ -546,7 +550,7 @@ public class SASLAuthentication {
}
hostname = new String(StringUtils.decodeBase64(hostname), CHARSET);
// Check if cerificate validation is disabled for s2s
// Check if certificate validation is disabled for s2s
// Flag that indicates if certificates of the remote server should be validated.
// Disabling certificate validation is not recommended for production environments.
boolean verify =
......@@ -557,19 +561,24 @@ public class SASLAuthentication {
}
// Check that hostname matches the one provided in a certificate
Connection connection = session.getConnection();
for (Certificate certificate : connection.getPeerCertificates()) {
for (String identity : CertificateManager.getPeerIdentities((X509Certificate) certificate)) {
// Verify that either the identity is the same as the hostname, or for wildcarded
// identities that the hostname ends with .domainspecified or -is- domainspecified.
if ((identity.startsWith("*.")
&& (hostname.endsWith(identity.replace("*.", "."))
|| hostname.equals(identity.replace("*.", ""))))
|| hostname.equals(identity)) {
authenticationSuccessful(session, hostname, null);
return Status.authenticated;
try {
X509Certificate trusted = CertificateManager.getEndEntityCertificate(connection.getPeerCertificates(), SSLConfig.getKeyStore(), SSLConfig.gets2sTrustStore());
if (trusted != null) {
for (String identity : CertificateManager.getPeerIdentities(trusted)) {
// Verify that either the identity is the same as the hostname, or for wildcarded
// identities that the hostname ends with .domainspecified or -is- domainspecified.
if ((identity.startsWith("*.")
&& (hostname.endsWith(identity.replace("*.", "."))
|| hostname.equals(identity.replace("*.", ""))))
|| hostname.equals(identity)) {
authenticationSuccessful(session, hostname, null);
return Status.authenticated;
}
}
}
} catch(IOException e) {
/// Keystore problem.
}
}
......
src/java/org/jivesoftware/util/CertificateManager.java
View file @ 78e4eff7
......@@ -37,9 +37,19 @@ import java.security.Provider;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Security;
import java.security.cert.CertPath;
import java.security.cert.CertPathBuilder;
import java.security.cert.CertPathBuilderException;
import java.security.cert.CertPathValidator;
import java.security.cert.CertPathValidatorException;
import java.security.cert.CertStore;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.security.cert.CertificateParsingException;
import java.security.cert.CollectionCertStoreParameters;
import java.security.cert.PKIXBuilderParameters;
import java.security.cert.TrustAnchor;
import java.security.cert.X509CertSelector;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Collection;
......@@ -47,6 +57,7 @@ import java.util.Collections;
import java.util.Date;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.LinkedList;
import java.util.List;
......@@ -208,6 +219,110 @@ public class CertificateManager {
}
}
/**
* Decide whether or not to trust the given supplied certificate chain, returning the
* End Entity Certificate in this case where it can, and null otherwise.
* A self-signed certificate will, for example, return null.
* For certain failures, we SHOULD generate an exception - revocations and the like.
*
* @param certChain an array of X509Certificate where the first one is the endEntityCertificate.
* @return a boolean indicating whether the endEntityCertificate should be trusted.
*/
public static X509Certificate getEndEntityCertificate(Certificate chain[],
KeyStore certStore, KeyStore trustStore) {
if (chain.length == 0) {
return null;
}
X509Certificate first = (X509Certificate) chain[0];
if (chain.length == 1
&& first.getSubjectDN().equals(first.getIssuerDN())) {
// Chain is single cert, and self-signed.
try {
if (trustStore.getCertificateAlias(first) != null) {
// Interesting case: trusted self-signed cert.
return first;
}
} catch (KeyStoreException e) {
// Ignore.
}
return null;
}
ArrayList<Object> all_certs = new ArrayList<Object>();
try {
// First, load up certStore contents into a CertStore.
// It's a mystery why these objects are different.
for (Enumeration<String> aliases = certStore.aliases(); aliases
.hasMoreElements();) {
String alias = aliases.nextElement();
if (certStore.isCertificateEntry(alias)) {
X509Certificate cert = (X509Certificate) certStore
.getCertificate(alias);
all_certs.add(cert);
}
}
// Now add the trusted certs.
for (Enumeration<String> aliases = trustStore.aliases(); aliases
.hasMoreElements();) {
String alias = aliases.nextElement();
if (trustStore.isCertificateEntry(alias)) {
X509Certificate cert = (X509Certificate) trustStore
.getCertificate(alias);
all_certs.add(cert);
}
}
// Finally, add all the certs in the chain except the first:
for (int i = 0; i < chain.length; ++i) {
all_certs.add(chain[i]);
}
CertStore cs = CertStore.getInstance("Collection",
new CollectionCertStoreParameters(all_certs));
X509CertSelector selector = new X509CertSelector();
selector.setCertificate(first);
// / selector.setSubject(first.getSubjectX500Principal());
PKIXBuilderParameters params = new PKIXBuilderParameters(
trustStore, selector);
params.addCertStore(cs);
params.setDate(new Date());
params.setRevocationEnabled(false);
/* Code here is the right way to do things. */
CertPathBuilder pathBuilder = CertPathBuilder
.getInstance(CertPathBuilder.getDefaultType());
CertPath cp = pathBuilder.build(params).getCertPath();
/**
* This section is an alternative to using CertPathBuilder which is
* not as complete (or safe), but will emit much better errors. If
* things break, swap around the code.
*
**** COMMENTED OUT. ****
ArrayList<X509Certificate> ls = new ArrayList<X509Certificate>();
for (int i = 0; i < chain.length; ++i) {
ls.add((X509Certificate) chain[i]);
}
for (X509Certificate last = ls.get(ls.size() - 1); !last
.getIssuerDN().equals(last.getSubjectDN()); last = ls
.get(ls.size() - 1)) {
X509CertSelector sel = new X509CertSelector();
sel.setSubject(last.getIssuerX500Principal());
ls.add((X509Certificate) cs.getCertificates(sel).toArray()[0]);
}
CertPath cp = CertificateFactory.getInstance("X.509").generateCertPath(ls);
****** END ALTERNATIVE. ****
*/
// Not entirely sure if I need to do this with CertPathBuilder.
// Can't hurt.
CertPathValidator pathValidator = CertPathValidator
.getInstance("PKIX");
pathValidator.validate(cp, params);
return (X509Certificate) cp.getCertificates().get(0);
} catch (CertPathBuilderException e) {
Log.warn("Path builder: " + e.getMessage());
} catch (CertPathValidatorException e) {
Log.warn("Path validator: " + e.getMessage());
} catch (Exception e) {
}
return null;
}
/**
* Returns the identities of the remote server as defined in the specified certificate. The
* identities are defined in the subjectDN of the certificate and it can also be defined in
......
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