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Posted to common-issues@hadoop.apache.org by "Duo Zhang (JIRA)" <ji...@apache.org> on 2016/08/23 10:07:22 UTC
[jira] [Updated] (HADOOP-13433) Race in UGI.reloginFromKeytab
[ https://issues.apache.org/jira/browse/HADOOP-13433?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Duo Zhang updated HADOOP-13433:
-------------------------------
Attachment: HADOOP-13433.patch
Let's fix the bug first. I found that the minikdc on trunk could reject a tgs request which uses a service ticket as TGT.
The difficulty of changing the relogin steps is that, the subject of UserGroupInformation can be passed from outside and UserGroupInformation is declared as LimitedPrivate, so it is not safe to switch subject after relogin. We need to discuss with the projects declared in LimitedPrivate annotations if we want to do this. I can file another issue to do this.
Thanks.
> Race in UGI.reloginFromKeytab
> -----------------------------
>
> Key: HADOOP-13433
> URL: https://issues.apache.org/jira/browse/HADOOP-13433
> Project: Hadoop Common
> Issue Type: Bug
> Components: security
> Reporter: Duo Zhang
> Attachments: HADOOP-13433.patch
>
>
> This is a problem that has troubled us for several years. For our HBase cluster, sometimes the RS will be stuck due to
> {noformat}
> 2016-06-20,03:44:12,936 INFO org.apache.hadoop.ipc.SecureClient: Exception encountered while connecting to the server :
> javax.security.sasl.SaslException: GSS initiate failed [Caused by GSSException: No valid credentials provided (Mechanism level: The ticket isn't for us (35) - BAD TGS SERVER NAME)]
> at com.sun.security.sasl.gsskerb.GssKrb5Client.evaluateChallenge(GssKrb5Client.java:194)
> at org.apache.hadoop.hbase.security.HBaseSaslRpcClient.saslConnect(HBaseSaslRpcClient.java:140)
> at org.apache.hadoop.hbase.ipc.SecureClient$SecureConnection.setupSaslConnection(SecureClient.java:187)
> at org.apache.hadoop.hbase.ipc.SecureClient$SecureConnection.access$700(SecureClient.java:95)
> at org.apache.hadoop.hbase.ipc.SecureClient$SecureConnection$2.run(SecureClient.java:325)
> at org.apache.hadoop.hbase.ipc.SecureClient$SecureConnection$2.run(SecureClient.java:322)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:396)
> at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1781)
> at sun.reflect.GeneratedMethodAccessor23.invoke(Unknown Source)
> at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at org.apache.hadoop.hbase.util.Methods.call(Methods.java:37)
> at org.apache.hadoop.hbase.security.User.call(User.java:607)
> at org.apache.hadoop.hbase.security.User.access$700(User.java:51)
> at org.apache.hadoop.hbase.security.User$SecureHadoopUser.runAs(User.java:461)
> at org.apache.hadoop.hbase.ipc.SecureClient$SecureConnection.setupIOstreams(SecureClient.java:321)
> at org.apache.hadoop.hbase.ipc.HBaseClient.getConnection(HBaseClient.java:1164)
> at org.apache.hadoop.hbase.ipc.HBaseClient.call(HBaseClient.java:1004)
> at org.apache.hadoop.hbase.ipc.SecureRpcEngine$Invoker.invoke(SecureRpcEngine.java:107)
> at $Proxy24.replicateLogEntries(Unknown Source)
> at org.apache.hadoop.hbase.replication.regionserver.ReplicationSource.shipEdits(ReplicationSource.java:962)
> at org.apache.hadoop.hbase.replication.regionserver.ReplicationSource.runLoop(ReplicationSource.java:466)
> at org.apache.hadoop.hbase.replication.regionserver.ReplicationSource.run(ReplicationSource.java:515)
> Caused by: GSSException: No valid credentials provided (Mechanism level: The ticket isn't for us (35) - BAD TGS SERVER NAME)
> at sun.security.jgss.krb5.Krb5Context.initSecContext(Krb5Context.java:663)
> at sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:248)
> at sun.security.jgss.GSSContextImpl.initSecContext(GSSContextImpl.java:180)
> at com.sun.security.sasl.gsskerb.GssKrb5Client.evaluateChallenge(GssKrb5Client.java:175)
> ... 23 more
> Caused by: KrbException: The ticket isn't for us (35) - BAD TGS SERVER NAME
> at sun.security.krb5.KrbTgsRep.<init>(KrbTgsRep.java:64)
> at sun.security.krb5.KrbTgsReq.getReply(KrbTgsReq.java:185)
> at sun.security.krb5.internal.CredentialsUtil.serviceCreds(CredentialsUtil.java:294)
> at sun.security.krb5.internal.CredentialsUtil.acquireServiceCreds(CredentialsUtil.java:106)
> at sun.security.krb5.Credentials.acquireServiceCreds(Credentials.java:557)
> at sun.security.jgss.krb5.Krb5Context.initSecContext(Krb5Context.java:594)
> ... 26 more
> Caused by: KrbException: Identifier doesn't match expected value (906)
> at sun.security.krb5.internal.KDCRep.init(KDCRep.java:133)
> at sun.security.krb5.internal.TGSRep.init(TGSRep.java:58)
> at sun.security.krb5.internal.TGSRep.<init>(TGSRep.java:53)
> at sun.security.krb5.KrbTgsRep.<init>(KrbTgsRep.java:46)
> ... 31 more
> {noformat}
> It rarely happens, but if it happens, the regionserver will be stuck and can never recover.
> Recently we added a log after a successful re-login which prints the private credentials, and finally catched the direct reason. After a successful re-login, we have two kerberos tickets in the credentials, one is the TGT, and the other is a service ticket. The strange thing is that, the service ticket is placed before TGT. This breaks the assumption of jdk's kerberos library. See http://hg.openjdk.java.net/jdk8u/jdk8u60/jdk/file/935758609767/src/share/classes/sun/security/jgss/krb5/Krb5InitCredential.java, the {{getTgt}} Method
> {code:title=Krb5InitCredential}
> return AccessController.doPrivileged(
> new PrivilegedExceptionAction<KerberosTicket>() {
> public KerberosTicket run() throws Exception {
> // It's OK to use null as serverPrincipal. TGT is almost
> // the first ticket for a principal and we use list.
> return Krb5Util.getTicket(
> realCaller,
> clientPrincipal, null, acc);
> }});
> {code}
> So here, the library will use the service ticket as TGT to acquire a service ticket, and KDC will reject the request since the 'TGT' does not start with 'krbtgt'. And it can never recover because in UGI, the re-login will check if there is a valid TGT first and no doubt, we have one...
> This usually happens when a secure connection initialization comes along with the re-login, and the end time indicates that the service ticket is acquired by the previous TGT. Since UGI does not prevent doAs and re-login happen at the same time, we believe that there is a race condition.
> After reading the code, we found a possible race condition.
> See http://hg.openjdk.java.net/jdk8u/jdk8u60/jdk/file/935758609767/src/share/classes/sun/security/jgss/krb5/Krb5Context.java, the {{initSecContext}} method, we will get TGT first, then check if there is already a service ticket, if not, acquire a service ticket using the TGT, and put it into the credentials.
> And in Krb5LoginModule.logout(the sun version), we will remove the kerberos tickets from the credentials first, and then destroy them.
> Here comes the race condition. Let T1 be the secure connection set up thread, T2 be the re-login thread.
> T1: get TGT
> T2: remove all tickets from credentials
> T1: check service ticket, none(since all tickets have been removed)
> T1: acquire a new service ticket using TGT and put it into the credentials
> T2: destroy all tickets
> T2: login, i.e., put a new TGT into the credentials.
> It is hard to write a UT to produce the problem because the racing code is in jdk, which is not written by us...
> Suggestions are welcomed. Thanks.
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