[cifs-protocol] SMB2_CREATE error code IO_REPARSE_TAG_NOT_HANDLED? - TrackingID#2211180040005873

[Volker Lendecke]

Am Fri, Nov 18, 2022 at 07:50:29PM +0000 schrieb Jeff McCashland (He/him):
> Have you seen this error over the wire 'in the wild'?
> IO_REPARSE_TAG_LX_CHR is documented in [MS-FSCC] as 'not meaningful
> over the wire', so artificially creating a 'bogus' reparse point in
> this manner might be considered a violation of protocol. We don't
> generally document the results of protocol violations.

No, I haven't seen this "in the wild". I'm playing with reparse points
right now and I want to understand what Samba will have to implement
to conform the Windows product behaviour. And it seems that Windows on
the FSCTL_SET_REPARSE_POINT accepts anything, but acts with an
undocumented error code if you want to use what was accepted by the
server.

> The error IO_REPARSE_TAG_NOT_HANDLED is an IFS error indicating that
> no filter driver was available to handle the reparse point (because
> it wasn't valid). It's likely documented in the IFS kit and/or the
> WDK.

To my understanding "not meaningful over the wire" does not mean that
the error code IO_REPARSE_TAG_NOT_HANDLED should not be documented. It
might be true that this makes no sense to actually query the value of
this reparse point over the wire, but clients might come across what
was set and what is used by pure server-side applications. There
should be protocol documentation for this, at least from my point of
view.

Thanks,

Volker