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https://issues.apache.org/jira/browse/ACCUMULO-3513?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14306004#comment-14306004
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Josh Elser commented on ACCUMULO-3513:
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bq. Oh. Interesting. So, the YARN process can securely authenticate itself with
the job controller (NodeManager? I'm not sure terminology here) before a job is
submitted, but the task doesn't have access to that.
ResourceManager, but yes, I think you have the point.
bq. How do they prevent the tasks from getting access to the parent process'
Kerberos keytab?
So, it's an entirely new process, so there's no shared memory. Keytabs on disk
should be protected by the filesystem.
bq. How are these tasks sandboxed?
A little C program is executed by the nodemanager which does your normal
fork(), drops permissions on the child process, and runs the actual yarn task.
bq. Could our Input/OutputFormat be configured to access this keytab?
No, for the above reason -- we cannot read it. If it was generally open, anyone
could impersonate the yarn processes.
bq. I guess you might not want to do that if you don't trust the job which was
submitted, but I'm not sure how we (Accumulo services) can trust that the
request is coming from a trusted YARN service, and not some other party which
maliciously gained access to a client's delegation token.
Like any password, it's expected that the delegation token is protected from
prying eyes. The time-limit on the validity of the delegation token helps
mitigate some concern, but that's a very small mitigation. We ultimately need
to rely on YARN (which it is doing) to keep the delegation token safe from
prying eyes from when it leaves the client's possession and makes it way to the
actual yarn task.
> Ensure MapReduce functionality with Kerberos enabled
> ----------------------------------------------------
>
> Key: ACCUMULO-3513
> URL: https://issues.apache.org/jira/browse/ACCUMULO-3513
> Project: Accumulo
> Issue Type: Bug
> Components: client
> Reporter: Josh Elser
> Assignee: Josh Elser
> Priority: Blocker
> Fix For: 1.7.0
>
> Attachments: ACCUMULO-3513-design.pdf
>
>
> I talked to [~devaraj] today about MapReduce support running on secure Hadoop
> to help get a picture about what extra might be needed to make this work.
> Generally, in Hadoop and HBase, the client must have valid credentials to
> submit a job, then the notion of delegation tokens is used by for further
> communication since the servers do not have access to the client's sensitive
> information. A centralized service manages creation of a delegation token
> which is a record which contains certain information (such as the submitting
> user name) necessary to securely identify the holder of the delegation token.
> The general idea is that we would need to build support into the master to
> manage delegation tokens to node managers to acquire and use to run jobs.
> Hadoop and HBase both contain code which implements this general idea, but we
> will need to apply them Accumulo and verify that it is M/R jobs still work on
> a kerberized environment.
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