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https://issues.apache.org/jira/browse/HDFS-7073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14140447#comment-14140447
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Yi Liu commented on HDFS-7073:
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Chris, thanks for quick update for this bulk of work.
The new approach is good. Agree that if the NameNode interaction falls back to
simple auth then we skip SASL for DataTransferProtocol too, that makes sense.
This can also protect from in secured cluster and fallback allowed, malicious
task listens on the DN's port and steal the block access token. Also in this
way, we don't need fallback exception to trigger retry as in the patch.
The new patch looks good to me, only few comments:
*1.* I think we may not need to pass {{fallbackToSimpleAuth}} for each call.
Since we do authentication for each connection, {{fallbackToSimpleAuth}} could
be as a variable of connection, then in _ProtobufRpcEngine_ and other rpc
engine, we can get _fallbackToSimpleAuth_ through the connection. Then the
logic looks more straight and clear?
*2.* I see there are two {{TODO}} for HA case in NameNodeProxies.java.
> Allow falling back to a non-SASL connection on DataTransferProtocol in
> several edge cases.
> ------------------------------------------------------------------------------------------
>
> Key: HDFS-7073
> URL: https://issues.apache.org/jira/browse/HDFS-7073
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: datanode, hdfs-client, security
> Reporter: Chris Nauroth
> Assignee: Chris Nauroth
> Attachments: HDFS-7073.1.patch, HDFS-7073.2.patch
>
>
> HDFS-2856 implemented general SASL support on DataTransferProtocol. Part of
> that work also included a fallback mode in case the remote cluster is running
> under a different configuration without SASL. I've discovered a few edge
> case configurations that this did not support:
> * Cluster is unsecured, but has block access tokens enabled. This is not
> something I've seen done in practice, but I've heard historically it has been
> allowed. The HDFS-2856 code relied on seeing an empty block access token to
> trigger fallback, and this doesn't work if the unsecured cluster actually is
> using block access tokens.
> * The DataNode has an unpublicized testing configuration property that could
> be used to skip the privileged port check. However, the HDFS-2856 code is
> still enforcing requirement of SASL when the ports are not privileged, so
> this would force existing configurations to make changes to activate SASL.
> This patch will restore the old behavior so that these edge case
> configurations will continue to work the same way.
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