Fix cname encoding in CertificateGenerator (#20745)

* Fix cname encoding in CertificateGenerator

* added license

* Added changelog

changelog/unreleased/issue-20738.toml

@@ -0,0 +1,5 @@
+type = "fixed"
+message = "Fix encoding of CName in generated CA certificates"
+
+issues = ["20738"]
+pulls = ["20745"]

graylog2-server/src/main/java/org/graylog/security/certutil/CertificateGenerator.java

@@ -17,6 +17,8 @@
 package org.graylog.security.certutil;
 
 import org.bouncycastle.asn1.x500.X500Name;
+import org.bouncycastle.asn1.x500.X500NameBuilder;
+import org.bouncycastle.asn1.x500.style.BCStyle;
 import org.bouncycastle.asn1.x509.BasicConstraints;
 import org.bouncycastle.asn1.x509.Extension;
 import org.bouncycastle.asn1.x509.GeneralName;
@@ -41,7 +43,8 @@ public class CertificateGenerator {
     public static KeyPair generate(CertRequest request) throws Exception {
         KeyPairGenerator keyGen = KeyPairGenerator.getInstance(KEY_GENERATION_ALGORITHM);
         java.security.KeyPair certKeyPair = keyGen.generateKeyPair();
-        X500Name name = new X500Name("CN=" + request.cnName());
+
+        final X500Name name = getX500Name(request.cnName());
 
         // TODO: cert serial number?
         BigInteger serialNumber = BigInteger.valueOf(System.currentTimeMillis());
@@ -84,4 +87,10 @@ public static KeyPair generate(CertRequest request) throws Exception {
         X509Certificate cert = new JcaX509CertificateConverter().getCertificate(certHolder);
         return new KeyPair(certKeyPair.getPrivate(), certKeyPair.getPublic(), cert);
     }
+
+    private static X500Name getX500Name(String cname) {
+        X500NameBuilder builder = new X500NameBuilder(BCStyle.INSTANCE);
+        builder.addRDN(BCStyle.CN, cname);
+        return builder.build();
+    }
 }

graylog2-server/src/test/java/org/graylog/security/certutil/CertificateGeneratorTest.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2020 Graylog, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the Server Side Public License, version 1,
+ * as published by MongoDB, Inc.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * Server Side Public License for more details.
+ *
+ * You should have received a copy of the Server Side Public License
+ * along with this program. If not, see
+ * <http://www.mongodb.com/licensing/server-side-public-license>.
+ */
+package org.graylog.security.certutil;
+
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.security.cert.X509Certificate;
+import java.time.Duration;
+
+class CertificateGeneratorTest {
+
+    @Test
+    void testDomainName() throws Exception {
+        final KeyPair pair = selfSigned("www.graylog.org");
+        final X509Certificate certificate = pair.certificate();
+        final String cn = certificate.getSubjectX500Principal().getName();
+        Assertions.assertThat(cn).isEqualTo("CN=www.graylog.org");
+    }
+
+    @Test
+    void testEscaping() throws Exception {
+        final KeyPair pair = selfSigned("Graylog, Inc.");
+        final X509Certificate certificate = pair.certificate();
+        final String cn = certificate.getSubjectX500Principal().getName();
+        Assertions.assertThat(cn).isEqualTo("CN=Graylog\\, Inc.");
+    }
+
+    private static KeyPair selfSigned(String cname) throws Exception {
+        final CertRequest req = CertRequest.selfSigned(cname).validity(Duration.ofDays(1));
+        return CertificateGenerator.generate(req);
+    }
+}