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  1. Kafka
  2. KAFKA-13474

Regression in dynamic update of broker certificate

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Details

    • Bug
    • Status: Open
    • Critical
    • Resolution: Unresolved
    • 2.7.0, 2.7.2, 2.8.1, 3.0.0
    • 3.3.0
    • core
    • None

    Description

      Problem

      It seems, after updating listener SSL certificate with dynamic broker configuration update, old certificate is somehow still used for broker client SSL factory. Because of this broker fails to create new connection to controller after old certificate expires.

      History

      Back in KAFKA-8336 there was an issue, when client-side SSL factory wasn't updating certificate, when it was changed with dynamic configuration. That bug have been fixed in version 2.3 and I can confirm, that dynamic update worked for us with kafka 2.4. But now we have updated clusters to 2.7 and see this (or at least similar) problem again.

      Affected versions

      First we've seen this on confluent 6.1.2, which (I think) based on kafka 2.7.0. Then I tried vanilla versions 2.7.0 and 2.7.2 and can reproduce problem on them just fine

      How to reproduce

      • Have zookeeper somewhere (in my example it will be "10.88.0.21:2181").
      • Get vanilla version 2.7.2 (or 2.7.0) from https://kafka.apache.org/downloads .
      • Make basic broker config like this (don't forget to actually create log.dirs):
        broker.id=1
        
        listeners=SSL://:9092
        advertised.listeners=SSL://localhost:9092
        
        log.dirs=/tmp/broker1/data
        
        zookeeper.connect=10.88.0.21:2181
        
        security.inter.broker.protocol=SSL
        ssl.protocol=TLSv1.2
        ssl.client.auth=required
        ssl.endpoint.identification.algorithm=
        ssl.keystore.type=PKCS12
        ssl.keystore.location=/tmp/broker1/secrets/broker1.keystore.p12
        ssl.keystore.password=changeme1
        ssl.key.password=changeme1
        ssl.truststore.type=PKCS12
        ssl.truststore.location=/tmp/broker1/secrets/truststore.p12
        ssl.truststore.password=changeme
        

        (I use here TLS 1.2 just so I can see client certificate in TLS handshake in traffic dump, you will get same error with default TLS 1.3 too)

        • Repeat this config for another 2 brokers, changing id, listener port and certificate accordingly.
      • Make basic client config (I use for it one of brokers' certificates):
        security.protocol=SSL
        ssl.key.password=changeme1
        ssl.keystore.type=PKCS12
        ssl.keystore.location=/tmp/broker1/secrets/broker1.keystore.p12
        ssl.keystore.password=changeme1
        ssl.truststore.type=PKCS12
        ssl.truststore.location=/tmp/broker1/secrets/truststore.p12
        ssl.truststore.password=changeme
        ssl.endpoint.identification.algorithm=
        
      • Create usual local self-signed PKI for test
        • generate self-signed CA certificate and private key. Place certificate in truststore.
        • create keys for broker certificates and create requests from them as usual (I'll use here same subject for all brokers)
        • create 2 certificates as usual
          openssl x509 \
                 -req -CAcreateserial -days 1 \
                 -CA ca/ca-cert.pem -CAkey ca/ca-key.pem \
                 -in broker1.csr -out broker1.crt
          
        • Use "faketime" utility to make third certificate expire soon:
          # date here is some point yesterday, so certificate will expire like 10-15 minutes from now
          faketime "2021-11-23 10:15" openssl x509 \
                 -req -CAcreateserial -days 1 \
                 -CA ca/ca-cert.pem -CAkey ca/ca-key.pem \
                 -in broker2.csr -out broker2.crt
          
        • create keystores from certificates and place them according to broker configs from earlier
      • Run 3 brokers with your configs like
        ./bin/kafka-server-start.sh server2.properties
        

        (I start it here without daemon mode to see logs right on terminal - just use "tmux" or something to run 3 brokers simultaneously)

        • you can check that one broker certificate will expire soon with
          openssl s_client -connect localhost:9093 </dev/null | openssl x509 -noout -text | grep -A2 Valid
          
      • Issue new certificate to replace one, which will expire soon, place it in keystore and replace old keystore with it.
      • Use dynamic configuration to make broker re-read keystore:
        ./bin/kafka-configs --command-config ssl.properties --bootstrap-server localhost:9092 --entity-type brokers --entity-name "2" --alter --add-config "listener.name.SSL.ssl.keystore.location=/tmp/broker2/secrets/broker2.keystore.p12"
        
        • You can check that broker now has new certificate on its listener with same command
          openssl s_client -connect localhost:9093 </dev/null | openssl x509 -noout -text | grep -A2 Valid
          
      • Wait until that old certificate expires and make some changes, which provoke broker to make new controller connection. For example if I have controller on broker "1" and expired certificate was on broker "2", then I restart broker "3".
      • On broker with expired certificate you will see in log something like
        INFO [broker-2-to-controller-send-thread]: Recorded new controller, from now on will use broker 1 (kafka.server.BrokerToControllerRequestThread)
        INFO [broker-2-to-controller] Failed authentication with localhost/127.0.0.1 (SSL handshake failed) (org.apache.kafka.common.network.Selector)
        ERROR [broker-2-to-controller] Connection to node 1 (localhost/127.0.0.1:9092) failed authentication due to: SSL handshake failed (org.apache.kafka.clients.NetworkClient)
        ERROR [broker-2-to-controller-send-thread]: Failed to send the following request due to authentication error: ClientRequest(expectResponse=true, callback=kafka.server.BrokerToControllerRequestThread$$Lambda$996/0x0000000801724c40@4d3e77ce, destination=1, correlationId=626, clientId=2, createdTimeMs=1637718291682, requestBuilder=AlterIsrRequestData(brokerId=2, brokerEpoch=293, topics=<some topic topology> kafka.server.BrokerToControllerRequestThread)
        

        and controller log will show something like

        INFO [SocketServer brokerId=1] Failed authentication with /127.0.0.1 (SSL handshake failed) (org.apache.kafka.common.network.Selector)
        

        and if broker with expired and changed certificate was controller itself, then it even could not connect to itself.

      • If you make traffic dump (and you use TLS 1.2 or less) then you will see that broker client connection tries to use old certificate in TLS handshake.

      Here is example of traffic dump, when broker with expired and dynamically changed certificate is current controller, so it can't connect to itself: failed-controller-single-session-20211119.pcap.gz
      In this example you will see that "Server" use new certificate and "Client" use old certificate, but it's same broker!

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            divijvaidya Divij Vaidya
            Shipenkov Igor Shipenkov
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              Created:
              Updated: