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From Andy LoPresto <alopre...@apache.org>
Subject Re:
Date Thu, 09 Aug 2018 19:00:22 GMT
I think we agree in our assessment of what the code is doing and disagree in our desire for
how that should occur. If OIDC is enabled and isClientAuthRequiredForRestApi() returns false,
the result is:

// Functionally equivalent to contextFactory.setNeedClientAuth(false);
contextFactory.setWantClientAuth(true);

That means that the server will request a client certificate if available, but will not require
its presence to negotiate the TLS handshake. You are asking to set contextFactory.setWantClientAuth(false);
as well, which will suppress the certificate selection dialog. If needClientAuth and wantClientAuth
are both false, client certificates cannot be used to authenticate as they will never be sent
from the browser. This will effectively allow you to choose between “certificates only”,
“certificates or other provider”, and “other provider only (no certificates)”.

I am saying that core NiFi *always* accepts client certificates as an authentication mechanism;
there is no scenario in which need and want are both set to false. This is by design. Again,
I am not saying this can never change, but because of the expectations, documentation, and
shared knowledge around this mechanism, changing it is (in my opinion) a major change, and
should not be done in a minor release. Other project members may (and probably do) disagree
with me.

A property in nifi.properties which defaults to “off” but when manually enabled can bypass
this requirement is an option. I don’t think we disagree on how to implement this specific
change; I think we differ only on how impactful it will be. My perspective comes from supporting
a large number of users with a broad variety of (often conflicting) requirements, and sometimes
(both they and I have) very little knowledge of the rest of their IT ecosystem. I believe
your perspective comes from a specific user with specific requirements. That’s why I recommended
making the localized change you need in a fork of the project, so you can achieve your objective
in a timeframe that is not blocked by other parties.

Andy LoPresto
alopresto@apache.org
alopresto.apache@gmail.com
PGP Fingerprint: 70EC B3E5 98A6 5A3F D3C4  BACE 3C6E F65B 2F7D EF69

> On Aug 9, 2018, at 11:48 AM, Curtis Ruck <curtis.ruck@gmail.com> wrote:
> 
> In my environment, by trying to enable OIDC, it returns false in that function you selected.
> 
> My suggestion, is that in the } else { block, changing the setWantClientAuth(true) to
setWantClientAuth(nifiproperties.isWantClientAuth()) which can default to true in the absence
of the setting.
> 
> By allowing a property to disable this check, would neuter the current X509 Authentication,
as it won't have a certificate to authenticate.  It would also address Shawn's concern of
for having his users cancel the first authentication popup.
> 
> It's not fixing AuthN/AuthZ, but its allowing us in special circumstances to disable
X509 easily.  In my environment, it's even preferable because we would use OIDC to redirect
to Apereo CAS, which does X509 Authentication itself.
> 
> --
> Curtis Ruck
> 
> 
> On Thu, Aug 9, 2018 at 2:43 PM Andy LoPresto <alopresto@apache.org <mailto:alopresto@apache.org>>
wrote:
> Hi Curtis,
> 
> There has definitely been some discussion about this and it is picking up recently. I
understand the difficulty faced when using NiFi in conjunction with a reverse proxy or external
identity provider. I am not saying the current way is perfect, or even the best.
> 
> …but…
> 
> Always allowing X.509 authentication has been the standard for years (due to NiFi’s
original design requirements), and changing this will have far-reaching impact on the application.
The additional identity providers have been added piece-meal as requirements arose, and because
of the multiple contexts NiFi supports, there are additional changes required for each —
issuing one time tokens for file downloads, etc.
> 
> The code you identified returns a boolean value, but it is not simply reading a boolean
flag from the properties file — it is calculating the presence/absence of the other (non-credential-based)
identity providers:
> 
> /**
>  * Returns true if client certificates are required for REST API. Determined
>  * if the following conditions are all true:
>  * <p>
>  * - login identity provider is not populated
>  * - Kerberos service support is not enabled
>  * - openid connect is not enabled
>  * - knox sso is not enabled
>  * </p>
>  *
>  * @return true if client certificates are required for access to the REST API
>  */
> public boolean isClientAuthRequiredForRestApi() {
>     return !isLoginIdentityProviderEnabled() && !isKerberosSpnegoSupportEnabled()
&& !isOidcEnabled() && !isKnoxSsoEnabled();
> }
> There is active planning for a complete rewrite of the authentication mechanism ordering,
but because this is such a wide-reaching change and will have substantial impact across the
project, I strongly advocate for this to go in a major release. As the number of users of
the project continues to grow, we have to balance improving the experience in edge scenarios
against more common scenarios. While I don’t mean to negate the times a reverse proxy is
required, it is not present in the majority of deployments, and the current model works sufficiently
in those deployments. We have to keep those deployments in mind as well while we make these
changes.
> 
> If you have an immediate need to deploy NiFi behind a reverse proxy and disable the X.509
requests, my honest suggestion would be to fork the repository and apply a patch to return
false from that method just as you specified. Unfortunately, that patch alone probably would
not be accepted into the upstream NiFi project at this time. It can certainly be documented
as a requirement for the rearchitected authentication mechanism moving forward.
> 
> Thanks for sharing your expectations and needs from the project, and hopefully we can
meet them soon.
> 
> 
> Andy LoPresto
> alopresto@apache.org <mailto:alopresto@apache.org>
> alopresto.apache@gmail.com <mailto:alopresto.apache@gmail.com>
> PGP Fingerprint: 70EC B3E5 98A6 5A3F D3C4  BACE 3C6E F65B 2F7D EF69
> 
>> On Aug 9, 2018, at 11:28 AM, Curtis Ruck <curtis.ruck@gmail.com <mailto:curtis.ruck@gmail.com>>
wrote:
>> 
>> FYSA,
>> 
>> This is where X509 is "always-on".
>> 
>> nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-jetty/src/main/java/org/apache/nifi/web/server/JettyServer.java#L781-L785
>> 
>> if (props.isClientAuthRequiredForRestApi()) {
>>    contextFactory.setNeedClientAuth(true);
>> } else {
>>    contextFactory.setWantClientAuth(true);
>> }
>> 
>> I believe in the short term, modifying this section to use nifi.properties to allow
us to provide a false to wantClientAuth, would address our concerns.
>> 
>> --
>> Curtis Ruck
>> 
>> 
>> On Thu, Aug 9, 2018 at 12:54 PM Curtis Ruck <curtis.ruck@gmail.com <mailto:curtis.ruck@gmail.com>>
wrote:
>> To support Shawn's statement even further.  If my customer can't get NiFi to operate
behind our reverse proxy, it won't be in our system.  I'm trying to find the easiest approach,
and NiFi's OIDC should be perfect, if X509 wasn't "wanted" up front.
>> 
>> I'd argue that all of the AuthN/AuthZ code should be abstracted out significantly
more than it currently is, with the ability to completely configure it via nifi.properties,
and mix-in custom AuthN/AuthZ solutions.
>> The ability to manage users/groups in NiFi's UI should be a toggle.
>> There should be an easy higher level API to use for group/role provisioning.  If
a new user "bob" open's NiFi and they have a "read-only" role, then they shouldn't need to
be manually provisioned in NiFi, and we my customer tries to minimize the number of unique
applications reaching into LDAP.  Every application that implements LDAP support implements
it differently, and they don't always scale up appropriately.
>> 
>> For example, i'm trying to get Apereo CAS 5.x working with Apache NiFi.  With CAS,
it can provide SAML 2.0, SAML 1.1, OpenID Connect, or CAS's custom protocols, which can support
Yubikey, Google Authentication, ADFS, Azure AD, etc.  Sadly, because of the wantClientAuth(true)
I can't use any of it.
>> 
>> I'm even willing to assist in providing some PRs to move NiFi in the right direction,
I just think we should figure out the higher level architecture/design a little better; especially
since NiFi's job is to help things integrate together, it's not being a good team player.
>> 
>> As much as I hate to say it, if NiFi was a proper Java EE project, I could just use
a war overlay to modify the AuthN/AuthZ to success; even if it was just a self-executing .war.
>> 
>> --
>> Curtis Ruck
>> 
>> 
>> On Thu, Aug 9, 2018 at 12:14 PM Shawn Weeks <sweeks@weeksconsulting.us <mailto:sweeks@weeksconsulting.us>>
wrote:
>> I'll clarify my statement a little as well with a workflow.
>> 
>> You open the NiFi UI Link
>> Chrome sees NiFi Asking for SSL and Prompts You for Cert
>> Then you get Prompts for Username and Password because of GSSAPI even though your
not on that REALM.
>> Then you get directed to the Identify Management Reverse Proxy URL for Knox SSO
>> Then you get prompted for your Certificate which you should select.
>> Then you might get prompted for Kerberos Again which you cancel
>> Finally your in NiFi.
>> 
>> Painful doesn't even begin to describe it lol.
>> 
>> 
>> Thanks
>> Shawn
>> From: Kevin Doran <kdoran@apache.org <mailto:kdoran@apache.org>>
>> Sent: Thursday, August 9, 2018 11:07:28 AM
>> To: users@nifi.apache.org <mailto:users@nifi.apache.org>
>> Subject: Re: Re:
>> 
>> Explaining to your end users that you should skip the first Certificate Prompt but
accept the second but only when you haven't logged in the current session is really painful
>> 
>> Wow, that sounds terrible. Confusing, accident prone, and frustrating to correct
mistakes (at least in my experience, forcing a browser to forget client certificate preferences
is difficult).
>> 
>> Thanks for sharing those details about your deployment scenario. This can definitely
be improved and I have some ideas for how to do it. I've cloned the issue to NiFi to make
sure we are tracking it for both projects [1][2]
>> 
>> [1] https://issues.apache.org/jira/browse/NIFIREG-189 <https://issues.apache.org/jira/browse/NIFIREG-189>
>> [2] https://issues.apache.org/jira/browse/NIFI-5504 <https://issues.apache.org/jira/browse/NIFI-5504>
>> 
>> On Thu, Aug 9, 2018 at 11:54 AM, Shawn Weeks <sweeks@weeksconsulting.us <mailto:sweeks@weeksconsulting.us>>
wrote:
>> The project I'm on is running into this issue as well and it gets particularly painful
when all of your server's are signed by the same root ca that signs your smart card logins
and your using something like KnoxSSO. Explaining to your end users that you should skip the
first Certificate Prompt but accept the second but only when you haven't logged in the current
session is really painful and shows major shortcoming between the back end authentication
between servers and front end ui authentication.
>> 
>> We can't even considering putting it behind our identify reverse proxies because
we can't turn off two way ssl.
>> 
>> Thanks
>> Shawnk
>> From: Kevin Doran <kdoran@apache.org <mailto:kdoran@apache.org>>
>> Sent: Thursday, August 9, 2018 10:47:56 AM
>> To: users@nifi.apache.org <mailto:users@nifi.apache.org>
>> Subject: Re:
>> 
>> sorry forgot the link. here it is:
>> 
>> [1] https://issues.apache.org/jira/projects/NIFIREG/issues/NIFIREG-189 <https://issues.apache.org/jira/projects/NIFIREG/issues/NIFIREG-189>
>> 
>> On Thu, Aug 9, 2018 at 11:47 AM, Kevin Doran <kdoran@apache.org <mailto:kdoran@apache.org>>
wrote:
>> Hi Curtis,
>> 
>> This has come up a few times. Unfortunately I don’t think there is currently an
easy way to disable X509-based identity extraction in NiFi today. There is an open JIRA for
the same issue in NiFi Registry [1]. NiFi Registry follows the same AuthN/AuthZ design (and
a fair amount of code) as NiFi, so this ticket should apply to NiFi as well.
>> 
>> Perhaps you could share more about your needs and use case on that ticket so that
when it gets implemented we could take that scenario with reverse proxies and OIDC into account?
>> 
>> Thanks,
>> Kevin
>> 
>> On Mon, Aug 6, 2018 at 10:23 AM, Curtis Ruck <curtis.ruck@gmail.com <mailto:curtis.ruck@gmail.com>>
wrote:
>> I'm trying to setup OIDC authentication, but with Nifi service existing behind a
reverse proxy, and for our other apps we use SSL Client Authentication between reverse proxy
and application, Nifi is picking up the Reverse Proxy's SSL Certificate and falling into X509
Authentication instead of OIDC.  Any idea how I can disable X509 authentication in Nifi?
>> 
>> Connecting directly to nifi, it triggers the proper OIDC redirects.
>> 
>> --
>> Curtis Ruck
>> 
>> 
>> 
> 


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