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 > > > > > > > > > > > > > > >