Xiao Chen updated HADOOP-13558:
    Fix Version/s: 2.7.4

> UserGroupInformation created from a Subject incorrectly tries to renew the 
> Kerberos ticket
> ------------------------------------------------------------------------------------------
>                 Key: HADOOP-13558
>                 URL: https://issues.apache.org/jira/browse/HADOOP-13558
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: security
>    Affects Versions: 2.7.2, 2.6.4, 3.0.0-alpha2
>            Reporter: Alejandro Abdelnur
>            Assignee: Xiao Chen
>             Fix For: 2.8.0, 2.9.0, 2.7.4, 3.0.0-alpha2
>         Attachments: HADOOP-13558.01.patch, HADOOP-13558.02.patch, 
> HADOOP-13558.branch-2.7.patch
> The UGI {{checkTGTAndReloginFromKeytab()}} method checks certain conditions 
> and if they are met it invokes the {{reloginFromKeytab()}}. The 
> {{reloginFromKeytab()}} method then fails with an {{IOException}} 
> "loginUserFromKeyTab must be done first" because there is no keytab 
> associated with the UGI.
> The {{checkTGTAndReloginFromKeytab()}} method checks if there is a keytab 
> ({{isKeytab}} UGI instance variable) associated with the UGI, if there is one 
> it triggers a call to {{reloginFromKeytab()}}. The problem is that the 
> {{keytabFile}} UGI instance variable is NULL, and that triggers the mentioned 
> {{IOException}}.
> The root of the problem seems to be when creating a UGI via the 
> {{UGI.loginUserFromSubject(Subject)}} method, this method uses the 
> {{UserGroupInformation(Subject)}} constructor, and this constructor does the 
> following to determine if there is a keytab or not.
> {code}
>   this.isKeytab = KerberosUtil.hasKerberosKeyTab(subject);
> {code}
> If the {{Subject}} given had a keytab, then the UGI instance will have the 
> {{isKeytab}} set to TRUE.
> It sets the UGI instance as it would have a keytab because the Subject has a 
> keytab. This has 2 problems:
> First, it does not set the keytab file (and this, having the {{isKeytab}} set 
> to TRUE and the {{keytabFile}} set to NULL) is what triggers the 
> {{IOException}} in the method {{reloginFromKeytab()}}.
> Second (and even if the first problem is fixed, this still is a problem), it 
> assumes that because the subject has a keytab it is up to UGI to do the 
> relogin using the keytab. This is incorrect if the UGI was created using the 
> {{UGI.loginUserFromSubject(Subject)}} method. In such case, the owner of the 
> Subject is not the UGI, but the caller, so the caller is responsible for 
> renewing the Kerberos tickets and the UGI should not try to do so.

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