keyboard-interactive

[Nicolas Williams]

On Wed, Jan 09, 2002 at 09:48:07PM -0600, Mark D. Roth wrote:
> On Wed Jan 09 23:21 2002 +0100, Markus Friedl wrote:
> OK, so how about this:
> 
>  * Call the main loop from the PAM conversation function with some
>    state telling it where it was called from.

Bingo. Make the mainloop reentrant.

>  * When the main loop gets the next message from the client, it can
>    return control to the PAM conversation function.

OR perhaps the mainloop can return to the conversation function only if
it's an INFO_RESPONSE message. Else, if handling continues as you
suggest then kbd-interactive messages can't be interleaved with any
others; whether or not sshd should work that way depends on the
protocol drafts.

>  * If the client sent an INFO_RESPONSE message, the PAM conversation
>    function returns the client's response, and the PAM transaction
>    continues normally.
> 
>  * If the client sent some other type of message, the conversation
>    function can return PAM_CONV_ERR to abort the PAM transaction.  It
>    should also set some state to indicate that the PAM transaction was
>    aborted.
> 
>  * When pam_authenticate() returns, if the transaction was aborted,
>    return control to the main loop to handle the request that the
>    client sent.
> 
> There are some obvious semantics to be worked out in terms of how the
> state is maintained, but the PAM code itself would be fairly
> straightforward.  Or is there something I'm missing here?

See above.

> -- 
> Mark D. Roth <roth at feep.net>
> http://www.feep.net/~roth/


Cheers,

Nico
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