CIFS named pipe support

[Jeff Layton-4]

While I was at SambaXP this past spring, Kai Blin and I had a long talk
about the named pipe support in CIFS (the IPC$ stuff).

Now, I'm not terribly well versed in the subtleties of how windows uses
IPC$ shares, but the points I took away from the discussion were:

1) windows can decide to talk to any server's IPC$ share at any time.
It doesn't require that the mount already be set up (though obviously,
you may need credentials).

2) the main consumer of this functionality should it ever materialize
will be WINE

Given this, I have to ask...what's the point in doing this with CIFS?
Wouldn't this functionality be better handled in userspace -- either
within WINE itself, or in a separate "cifsipc" daemon or something?

When I look at what we have in CIFS so far, I don't see it as a
good fit. In order to use the IPC$ share, you're going to have to have
something mount these filesystems on the fly as WINE needs them. Maybe
you can hack up autofs to do it, or maybe WINE can somehow trigger
these mounts.

The only real advantage would be that you *might* end up sharing
sockets between the IPC$ share and other mounts on the box, but even
that's not a given. It just seems like this solution is adding a lot
more moving parts than if WINE were to do this itself in userspace (or
through a daemon or something).

Is there something I'm missing here?
--
Jeff Layton <jlayton@...>
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[Volker Lendecke]

On Thu, Sep 24, 2009 at 08:09:44AM -0400, Jeff Layton wrote:
> Is there something I'm missing here?

The main one is authentication. People might want to ride on
the credentials used in the cifs filesystem.

Volker


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[Jeff Layton-4]

On Thu, 24 Sep 2009 14:47:23 +0200
Volker Lendecke <Volker.Lendecke@...> wrote:

> On Thu, Sep 24, 2009 at 08:09:44AM -0400, Jeff Layton wrote:
> > Is there something I'm missing here?
>
> The main one is authentication. People might want to ride on
> the credentials used in the cifs filesystem.
>
> Volker

The problem though is that you won't necessarily have credentials for
random_server_X that WINE wants to talk to.

That's sort of my point. The current CIFS-based solution sort of
requires that you have some way to know ahead of time what hosts you're
going to talk to, and that's not necessarily the case with apps that run
under WINE.

--
Jeff Layton <jlayton@...>
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[Volker Lendecke]

On Thu, Sep 24, 2009 at 09:34:00AM -0400, Jeff Layton wrote:
> The problem though is that you won't necessarily have credentials for
> random_server_X that WINE wants to talk to.
>
> That's sort of my point. The current CIFS-based solution sort of
> requires that you have some way to know ahead of time what hosts you're
> going to talk to, and that's not necessarily the case with apps that run
> under WINE.

So WINE should probably just connect to winbind to get its
credentials when it wants transparent authentication.

Volker


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[Jeff Layton-4]

On Thu, 24 Sep 2009 18:18:12 +0200
Volker Lendecke <Volker.Lendecke@...> wrote:

> On Thu, Sep 24, 2009 at 09:34:00AM -0400, Jeff Layton wrote:
> > The problem though is that you won't necessarily have credentials for
> > random_server_X that WINE wants to talk to.
> >
> > That's sort of my point. The current CIFS-based solution sort of
> > requires that you have some way to know ahead of time what hosts you're
> > going to talk to, and that's not necessarily the case with apps that run
> > under WINE.
>
> So WINE should probably just connect to winbind to get its
> credentials when it wants transparent authentication.
>

That sounds reasonable. Might even be nice to eventually teach
cifs.upcall to do that too...

--
Jeff Layton <jlayton@...>
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