Require SSL certificate hash on login by default

Note that it's possible to set a config option to disable this functionality
on a per-environment basis (we're disabling it for sandbox), but in general
SSL certificate hashes should be required for increased security.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=225053496

java/google/registry/config/RegistryConfig.java

@@ -573,6 +573,17 @@ public final class RegistryConfig {
       return beamBucketUrl + "/templates/spec11";
     }
 
+    /**
+     * Returns whether an SSL certificate hash is required to log in via EPP and run flows.
+     *
+     * @see google.registry.flows.TlsCredentials
+     */
+    @Provides
+    @Config("requireSslCertificates")
+    public static boolean provideRequireSslCertificates(RegistryConfigSettings config) {
+      return config.registryPolicy.requireSslCertificates;
+    }
+
     /**
      * Returns the default job zone to run Apache Beam (Cloud Dataflow) jobs in.
      *

java/google/registry/config/RegistryConfigSettings.java

@@ -92,6 +92,7 @@ public class RegistryConfigSettings {
     public String rdapTos;
     public String rdapTosStaticUrl;
     public String spec11EmailBodyTemplate;
+    public boolean requireSslCertificates;
   }
 
   /** Configuration for Cloud Datastore. */

java/google/registry/config/files/default-config.yaml

@@ -183,6 +183,11 @@ registryPolicy:
     If you have any questions regarding this notice, please contact
     {REPLY_TO_EMAIL}.
 
+  # Whether to require an SSL certificate hash in order to be able to log in
+  # via EPP and run commands. This can be false for testing environments but
+  # should generally be true for production environments, for added security.
+  requireSslCertificates: true
+
 datastore:
   # Number of commit log buckets in Datastore. Lowering this after initial
   # install risks losing up to a days' worth of differential backups.

java/google/registry/flows/TlsCredentials.java

@@ -26,6 +26,7 @@ import com.google.common.net.HostAndPort;
 import com.google.common.net.InetAddresses;
 import dagger.Module;
 import dagger.Provides;
+import google.registry.config.RegistryConfig.Config;
 import google.registry.flows.EppException.AuthenticationErrorException;
 import google.registry.model.registrar.Registrar;
 import google.registry.request.Header;
@@ -54,14 +55,17 @@ public class TlsCredentials implements TransportCredentials {
 
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
 
+  private final boolean requireSslCertificates;
   private final String clientCertificateHash;
   private final InetAddress clientInetAddr;
 
   @Inject
   @VisibleForTesting
   public TlsCredentials(
+      @Config("requireSslCertificates") boolean requireSslCertificates,
       @Header("X-SSL-Certificate") String clientCertificateHash,
       @Header("X-Forwarded-For") Optional<String> clientAddress) {
+    this.requireSslCertificates = requireSslCertificates;
     this.clientCertificateHash = clientCertificateHash;
     this.clientInetAddr = clientAddress.isPresent() ? parseInetAddress(clientAddress.get()) : null;
   }
@@ -112,13 +116,17 @@ public class TlsCredentials implements TransportCredentials {
    * @throws MissingRegistrarCertificateException if frontend didn't send certificate hash header
    * @throws BadRegistrarCertificateException if registrar requires certificate and it didn't match
    */
-  private void validateCertificate(Registrar registrar) throws AuthenticationErrorException {
+  @VisibleForTesting
+  void validateCertificate(Registrar registrar) throws AuthenticationErrorException {
     if (isNullOrEmpty(registrar.getClientCertificateHash())
         && isNullOrEmpty(registrar.getFailoverClientCertificateHash())) {
-      logger.atInfo().log(
-          "Skipping SSL certificate check because %s doesn't have any certificate hashes on file",
-          registrar.getClientId());
-      return;
+      if (requireSslCertificates) {
+        throw new RegistrarCertificateNotConfiguredException();
+      } else {
+        // If the environment is configured to allow missing SSL certificate hashes and this hash is
+        // missing, then bypass the certificate hash checks.
+        return;
+      }
     }
     if (isNullOrEmpty(clientCertificateHash)) {
       logger.atInfo().log("Request did not include X-SSL-Certificate");
@@ -165,6 +173,14 @@ public class TlsCredentials implements TransportCredentials {
     }
   }
 
+  /** Registrar certificate is not configured. */
+  public static class RegistrarCertificateNotConfiguredException
+      extends AuthenticationErrorException {
+    public RegistrarCertificateNotConfiguredException() {
+      super("Registrar certificate is not configured");
+    }
+  }
+
   /** Registrar IP address is not in stored whitelist. */
   public static class BadRegistrarIpAddressException extends AuthenticationErrorException {
     public BadRegistrarIpAddressException() {

java/google/registry/tools/ValidateLoginCredentialsCommand.java

@@ -78,7 +78,7 @@ final class ValidateLoginCredentialsCommand implements CommandWithRemoteApi {
     Registrar registrar =
         checkArgumentPresent(
             Registrar.loadByClientId(clientId), "Registrar %s not found", clientId);
-    new TlsCredentials(clientCertificateHash, Optional.of(clientIpAddress))
+    new TlsCredentials(true, clientCertificateHash, Optional.of(clientIpAddress))
         .validate(registrar, password);
     checkState(!registrar.getState().equals(Registrar.State.PENDING), "Account pending");
   }