hadoop-hdfs-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Erik Krogen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-14305) Serial number in BlockTokenSecretManager could overlap between different namenodes
Date Fri, 22 Feb 2019 16:20:00 GMT

    [ https://issues.apache.org/jira/browse/HDFS-14305?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16775329#comment-16775329
] 

Erik Krogen commented on HDFS-14305:
------------------------------------

Thanks for reporting this [~csun]. Given that the serial numbers are randomly distributed
through a 32-bit space the chance of collision should be low, but agreed that we need to fix
this to ensure a lack of collision. [~hexiaoqiao], I agree with your {{POSITIVE_MASK}} approach,
but why not just do this within {{setSerialNo()}} itself instead of doing an additional check
later?

> 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: security
>            Reporter: Chao Sun
>            Assignee: Chao Sun
>            Priority: Major
>         Attachments: HDFS-14305.001.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.



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)

---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscribe@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-help@hadoop.apache.org


Mime
View raw message