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https://issues.apache.org/jira/browse/HDFS-14305?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Erik Krogen updated HDFS-14305:
-------------------------------
    Component/s: namenode

> Serial number in BlockTokenSecretManager could overlap between different 
> namenodes
> ----------------------------------------------------------------------------------
>
>                 Key: HDFS-14305
>                 URL: https://issues.apache.org/jira/browse/HDFS-14305
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode, security
>            Reporter: Chao Sun
>            Assignee: He Xiaoqiao
>            Priority: Major
>         Attachments: HDFS-14305.001.patch, HDFS-14305.002.patch, 
> HDFS-14305.003.patch, HDFS-14305.004.patch, HDFS-14305.005.patch, 
> HDFS-14305.006.patch
>
>
> Currently, a {{BlockTokenSecretManager}} starts with a random integer as the 
> initial serial number, and then use this formula to rotate it:
> {code:java}
>     this.intRange = Integer.MAX_VALUE / numNNs;
>     this.nnRangeStart = intRange * nnIndex;
>     this.serialNo = (this.serialNo % intRange) + (nnRangeStart);
>  {code}
> while {{numNNs}} is the total number of NameNodes in the cluster, and 
> {{nnIndex}} is the index of the current NameNode specified in the 
> configuration {{dfs.ha.namenodes.<nameservice>}}.
> However, with this approach, different NameNode could have overlapping ranges 
> for serial number. For simplicity, let's assume {{Integer.MAX_VALUE}} is 100, 
> and we have 2 NameNodes {{nn1}} and {{nn2}} in configuration. Then the ranges 
> for these two are:
> {code}
> nn1 -> [-49, 49]
> nn2 -> [1, 99]
> {code}
> This is because the initial serial number could be any negative integer.
> Moreover, when the keys are updated, the serial number will again be updated 
> with the formula:
> {code}
> this.serialNo = (this.serialNo % intRange) + (nnRangeStart);
> {code}
> which means the new serial number could be updated to a range that belongs to 
> a different NameNode, thus increasing the chance of collision again.
> When the collision happens, DataNodes could overwrite an existing key which 
> will cause clients to fail because of {{InvalidToken}} error.



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