"remove ZKTrustManager entirely from the codebase" - what is the impact on
backward compatibility if this is done? Why wouldn't we keep this as an
option (not the default?) to ensure folks won't experience a "gap" when
migrating to new versions. We could phase it out over time as part of such
a plan (at least n-1 compatibility is something we have guaranteed in the
past)
Patrick
On Fri, Jun 9, 2023 at 9:29 AM Szalay-Bekő Máté <szalay.beko.m...@gmail.com>
wrote:
> yeah, I remember these tickets, thanks for picking them up!
> I agree and like the solution you proposed, in general in the long term it
> is good not to use a custom trust manager, but rely on the standard one.
>
> Máté
>
>
> On Fri, Jun 9, 2023 at 2:08 PM Enrico Olivelli <eolive...@gmail.com>
> wrote:
>
> > Il giorno ven 9 giu 2023 alle ore 14:07 Andor Molnar
> > <an...@apache.org> ha scritto:
> > >
> > > I'd like to backport this to the 3.8 branch too.
> > >
> > > Let's say I'll add new "zookeeper.fips-mode" parameter which will be
> > > "false" by default in 3.8 and "true" for 3.9.0.
> >
> > I am +1
> > ZK 3.9 will take time to be adopted and this is an important security
> > related topic
> >
> > Enrico
> >
> > >
> > > Thoughts?
> > >
> > > Andor
> > >
> > >
> > >
> > > On Fri, 2023-06-09 at 13:55 +0200, Enrico Olivelli wrote:
> > > > I think that switching to
> > > > sslParameters.setEndpointIdentificationAlgorithm("HTTPS"); is a good
> > > > option.
> > > > The less tweaks we have about Security code the better.
> > > >
> > > >
> > > > It would be great to see this in 3.9.0.
> > > >
> > > > Enrico
> > > >
> > > > Il giorno ven 9 giu 2023 alle ore 13:42 Andor Molnar
> > > > <an...@apache.org> ha scritto:
> > > > > Hi zk folks,
> > > > >
> > > > > Problem(s)
> > > > > ==========
> > > > >
> > > > > One problem that we're having with a custom Trust Manager in ZK is
> > > > > that
> > > > > FIPS doesn't allow that:
> > > > >
> > > > > https://issues.apache.org/jira/browse/ZOOKEEPER-4393
> > > > >
> > > > > In FIPS mode the only allowed TrustManager in the JDK is
> > > > > X509TrustManagerImpl which is the default implementation. The class
> > > > > is
> > > > > final, so extending it is not an option unfortunately.
> > > > >
> > > > > The intention behind implementing a custom trust manager in ZK was,
> > > > > I
> > > > > believe, the need for server and client-side hostname verification.
> > > > > Hostname verification officially is not part of the SSL/TLS
> > > > > protocol,
> > > > > it's the responsibility of an upper level protocol like HTTPS.
> > > > >
> > > > > Hacking hostname verification in the SSL handshake is nice and was
> > > > > working fine so far, but unfortunately breaks the FIPS standard.
> > > > >
> > > > > Another annoying issue with ZKTrustManager is the need for reverse
> > > > > DNS
> > > > > lookup. This is usually needed when the hostname of the certificate
> > > > > provider is not known at the time of handshake. For instance, when
> > > > > somebody connects the client via IP address, which is generally not
> > > > > recommended when TLS is active in the client-server protocol.
> > > > >
> > > > > The bigger problem I've found is in the leader election: when a
> > > > > peer
> > > > > connects with a smaller id, the node will close the existing
> > > > > connection
> > > > > and opens a new one in the other direction, based on the
> > > > > information
> > > > > received in the InitialMessage from the peer which only contains
> > > > > the IP
> > > > > address, not the hostname. Therefore TrustManager needs to perform
> > > > > reverse DNS lookup.
> > > > >
> > > > > Tickets about reverse DNS lookup issues:
> > > > > https://issues.apache.org/jira/browse/ZOOKEEPER-3860
> > > > > https://issues.apache.org/jira/browse/ZOOKEEPER-4268
> > > > >
> > > > > Proposal
> > > > > ========
> > > > >
> > > > > I suggest to remove ZKTrustManager entirely from the codebase and
> > > > > use
> > > > > the built-in, FIPS-Enabled X509TrustManagerImpl instead. It has the
> > > > > downside of losing hostname verification, but we have an option to
> > > > > re-
> > > > > enable it in client-server communication: Netty has built-in
> > > > > support
> > > > > for it, we just need to do
> > > > >
> > > > > sslParameters.setEndpointIdentificationAlgorithm("HTTPS");
> > > > >
> > > > > when creating the SSLEngine and that will result in a behaviour
> > > > > very
> > > > > similar to what we provide currently. I can show some examples.
> > > > >
> > > > > What we will truly lose is the hostname verification option in the
> > > > > Quorum and Leader Election protocols. Since in these protocols we
> > > > > manipulate the sockets directly, we would need to implement the
> > > > > verification manually.
> > > > >
> > > > > What do you think about this trade-off?
> > > > >
> > > > > Of course, we can put this change behind a feature flag "fips-
> > > > > mode",
> > > > > which will lead to a new mode in ZooKeeper that is actually less
> > > > > strict
> > > > > as the original behaviour.
> > > > >
> > > > > Regards,
> > > > > Andor
> > > > >
> > > > >
> > > > >
> > >
> >
>
