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From "Marc P." <>
Subject Re: BatchWriter Auth/Audit Question
Date Fri, 19 Aug 2016 18:30:23 GMT
Funny, exactly the same thing I mentioned to Josh last night. Are you
watching us?

 In something I"m doing now I'm making the thrift calls and modeled it
after what the client code does; however,
once I removed the authenticateUser my throughput increased by 25 per cent.
In my trace table it was by and large the greatest audited call.

I think we could change how that works and potentially keep that out of
band. The fail fast is great if the user doesn't have permissions to that
table and may save the server some work...but as it is now, I'm always
authenticated and I'm causing more work for the server. Perhaps we let the
natural exception that's thrown stop the client ( if it's being a good
client ). I think the 25 per cent improvement was well worth the
alternative risk.

On Fri, Aug 19, 2016 at 2:16 PM, Mike Drob <> wrote:

> Devs,
> I was recently running a 1.7.2 cluster under a heavy write workload and
> noticed a _lot_ of audit messages showing up in the logs. After some
> digging, I found that one of the causes is the following call chain:
> TabletServerBatchWriter::sendMutationsToTabletServer
> calls TabletServer.ThriftClientHandler::startUpdate
> calls SecurityOperation::authenticateUser <-- always return true
> calls SecurityOperation::canAskAboutUser <-- always return true
> calls AuditedSecurityOperation::canPerformSystemActions <-- fails; logs
> "action: performSystemAction"
> calls AuditedSecurityAction::authenticate <-- succeeds; logs "action:
> authenticate;"
> There are two separate but related problems here, I think, that I want to
> confirm.
> When startUpdate calls security.authenticateUser(credentials,
> credentials);
> there is the comment that this is done to "// Make sure user is real"
> presumably to fail fast. This makes sense, but does it actually work? In
> authenticateUser and canAskAboutUser we end up comparing the two
> credentials to each other and this will always succeed because they're the
> same object. I expect the write fails later in the TabletServer code,
> possibly in the UpdateSession, but I haven't been able to untangle this
> part yet.
> Second, I think it makes sense to switch the order of the OR in
> 'canAskAboutUser.' If this is in the write path, then it seems like the
> most common case would be users asking about themselves, so we should check
> that before checking if a user is an admin. This also has the advantage of
> removing two uninformative audit log lines. We won't have an audit message
> that somebody wrote data, but we don't have that currently anyway.
> I did some visual spot checking and this looks like an issue in master
> also, but I haven't run that code to find out.
> Thoughts?
> Mike

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