Nuances of MIT Kerberos prompting

Russ Allbery eagle at eyrie.org
Mon Mar 9 15:30:23 EDT 2020


Greg Hudson <ghudson at mit.edu> writes:

> Yes.  For this prompter call, name is NULL, banner is the formatted
> expiration warning, and num_prompts is 0.

Thanks!

> Ah, two responder calls, not two prompter calls.  I was looking at the
> wrong code paths.

Oh, sorry, poor bug report on my part.

> Now that I look a the PKINIT responder logic, I agree that there is a
> bug.  In the second call to k5_preauth(), we are processing the KDC
> PKINIT padata supplied alongside the issued ticket, in order to
> authenticate the KDC response and set the correct reply key.  PKINIT
> does not need access to client certificates at this stage, but
> pkinit_client_prep_questions() re-asks questions for its recorded
> identities without checking the padata type or any other state that
> would indicate where it is in the process.  I will file a ticket.

Thanks!

> (The real reason kinit isn't affected is that it doesn't use a responder
> callback.)

Yes, that makes perfect sense in retrospect.  I should have started with
gdb before speculating.

-- 
Russ Allbery (eagle at eyrie.org)             <https://www.eyrie.org/~eagle/>


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