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workaround for OpenFire: check CN first in self signed certs 

The self signed certificates created by OpenFire (Not sure if other
certs are affected as well) will crash the Java/Android TLS stack when
accessing getSubjectAlternativeNames() on the the peer certificate.

This usually goes unnoticed in other applications since the
DefaultHostnameVerifier checkes the CN first. That however is a
violation of RFC6125 section 6.4.4 which requires us to check for the
existence of SAN first.

This commit adds a work around where in self signed certificates we
check for the CN first as well. (Avoiding the call to
getSubjectAlternativeNames())
This commit is contained in:
Daniel Gultsch 2017-07-16 11:05:19 +02:00
parent dfa17d1339
commit 8afe7efc2c
1 changed files with 32 additions and 6 deletions
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38
src/main/java/eu/siacs/conversations/crypto/XmppDomainVerifier.java
View File

@ -16,12 +16,12 @@ import org.bouncycastle.cert.jcajce.JcaX509CertificateHolder;
import java.io.IOException;
import java.security.cert.Certificate;
import java.security.cert.CertificateEncodingException;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLSession;
import de.duenndns.ssl.DomainHostnameVerifier;
@ -41,6 +41,13 @@ public class XmppDomainVerifier implements DomainHostnameVerifier {
return false;
}
X509Certificate certificate = (X509Certificate) chain[0];
if (isSelfSigned(certificate)) {
List<String> domains = getCommonNames(certificate);
if (domains.size() == 1 && domains.get(0).equals(domain)) {
Log.d(LOGTAG,"accepted CN in cert self signed cert for "+domain);
return true;
}
}
Collection<List<?>> alternativeNames = certificate.getSubjectAlternativeNames();
List<String> xmppAddrs = new ArrayList<>();
List<String> srvNames = new ArrayList<>();
@ -71,11 +78,7 @@ public class XmppDomainVerifier implements DomainHostnameVerifier {
}
}
if (srvNames.size() == 0 && xmppAddrs.size() == 0 && domains.size() == 0) {
X500Name x500name = new JcaX509CertificateHolder(certificate).getSubject();
RDN[] rdns = x500name.getRDNs(BCStyle.CN);
for (int i = 0; i < rdns.length; ++i) {
domains.add(IETFUtils.valueToString(x500name.getRDNs(BCStyle.CN)[i].getFirst().getValue()));
}
domains.addAll(domains);
}
Log.d(LOGTAG, "searching for " + domain + " in srvNames: " + srvNames + " xmppAddrs: " + xmppAddrs + " domains:" + domains);
if (hostname != null) {
@ -90,6 +93,20 @@ public class XmppDomainVerifier implements DomainHostnameVerifier {
}
}
private static List<String> getCommonNames(X509Certificate certificate) {
List<String> domains = new ArrayList<>();
try {
X500Name x500name = new JcaX509CertificateHolder(certificate).getSubject();
RDN[] rdns = x500name.getRDNs(BCStyle.CN);
for (int i = 0; i < rdns.length; ++i) {
domains.add(IETFUtils.valueToString(x500name.getRDNs(BCStyle.CN)[i].getFirst().getValue()));
}
return domains;
} catch (CertificateEncodingException e) {
return domains;
}
}
private static Pair<String, String> parseOtherName(byte[] otherName) {
try {
ASN1Primitive asn1Primitive = ASN1Primitive.fromByteArray(otherName);
@ -133,6 +150,15 @@ public class XmppDomainVerifier implements DomainHostnameVerifier {
return false;
}
private boolean isSelfSigned(X509Certificate certificate) {
try {
certificate.verify(certificate.getPublicKey());
return true;
} catch (Exception e) {
return false;
}
}
@Override
public boolean verify(String domain, SSLSession sslSession) {
return verify(domain,null,sslSession);