Expected behavior of nested UserGroupInformation

[Bertrand Dechoux <de...@gmail.com>]

Hi,

I am using UserGroupInformation.doAs(...) in order to launch a job
programmatically from a remote application.
I was wondering : what is the expected behavior of nested
UserGroupInformation?

Is it the same as with Jaas? Which is, if I am not mistaken, the last inner
'subject' is used?
If that's the case, UserGroupInformation can not be used to enforce that a
given code will be executed with the provided user, as the action might
nest a inner call with its own user.
That might be a security threat if there is not authentication (like
Kerberos).

Can someone confirm/infirm that?

Regards

Bertrand