Intercept SSLHandshakeException in Spring boot

Question

We have a rest API written in SpringBoot using a 2-way ssl Auth. We would like to send 401 HTTP status code when the user selects the wrong/expired client certificate.

When it happens I can see the exception:

javax.net.ssl.SSLHandshakeException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

The API starts normally and works fine. The exception occurs whenever the user tries to call my api selecting a wrong client certificate or invalid. In this case I would like to return 401 to the caller

Spring boot is configured with Tomcat and @EnableWebSecurity

http.x509().subjectPrincipalRegex("XXXXXX").userDetailsService(this.userDetailsService);
((RequiresChannelUrl)http.requiresChannel().anyRequest()).requiresSecure();
....
 http.exceptionHandling()
                    .authenticationEntryPoint(new HttpStatusEntryPoint(HttpStatus.UNAUTHORIZED))


public TomcatConnectorCustomizer httpsConnectorCustomizer(....) {
    return (connector) -> {
        connector.setScheme("https");
        connector.setPort(port);
        Http11NioProtocol protocol = (Http11NioProtocol) connector.getProtocolHandler();
        protocol.setSSLEnabled(true);
        protocol.setSecure(true);
        protocol.setPort(port);
        protocol.setClientAuth("optional");
        protocol.setKeystoreFile(...);
        protocol.setKeystorePass(...);
        protocol.setKeystoreType(...);
        protocol.setKeyAlias(...);
        protocol.setTruststoreFile(...);
        protocol.setTruststorePass(...);
        protocol.setTruststoreType(...);
    };
}

Here the stack trace:

DirectJDKLog.java:175 [] Handshake failed during wrap
javax.net.ssl.SSLHandshakeException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
at java.base/sun.security.ssl.Alert.createSSLException(Alert.java:131)
...
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
at java.base/sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:439)
....
....
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
at java.base/sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141)

The browser shows: ERR_BAD_SSL_CLIENT_AUTH_CERT
Is it possible to catch this exception in SpringBoot and send a specific HTTP status code?

It seems that the exception is deep down in java/tomcat and so far I was not able to catch it.

Answer 1

You won't be able to send a HTTP status code, because establishing the connection fails before you start talking HTTP.

See https://www.cloudflare.com/learning/ssl/what-happens-in-a-tls-handshake/ for an intro to SSL / TLS