[linux-cifs-client] Re: No legacy mount possible at all ANYMORE? - the kernel option CONFIG_CIFS_WEAK_PW_HASH

[Steve Langasek]

Hi Guenter,

On Sat, Mar 15, 2008 at 05:33:24AM +0100, Guenter Kukkukk wrote:
> if (smbfs_has_been_removed && kernel_has_been_build_without_CONFIG_CIFS_WEAK_PW_HASH) {
>      printf ("Sorry, 2008 - you cannot mount ANY legacy server anymore!\n");
> }

>  - the kernel module smbfs.ko will be removed very soon.
>  - also the (original!!!) samba userland helpers smbmount,
>    smbmnt and smbumount

> The daily answer "just mount cifs" is _critical_ regarding
> legacy servers like win9x/me, os/2, dos, ...

> WHY:
> ====
> Even if cifs vfs would support all features of smbfs -
> which is NOT the case - there's is a REAL problem NOW:

>    if the todays or future kernels are _not_ build with
>    CONFIG_CIFS_WEAK_PW_HASH, then _all_ legacy support
>    just has _gone_ !

> Any _new_ legacy additions to cifs vfs would be worthless,
> cause the _mount_ would not succeed at all.

Thanks for pointing this out.  I've filed a bug report with the Ubuntu
kernel team requesting that this option be enabled for the upcoming 8.04
release, and it should also be enabled in an upcoming Debian kernel upload.

> The new debian/ubuntu re-written "faking" smbmount and smbumount
> do not help at all - to me, that's "silly nonsense" - sorry!

That's your opinion (and not a very constructive approach).  The mapping of
smbfs to cifs is being done to provide as smooth as possible of a
transition for users currently using the smbfs driver.  I'm confident that
99% of the users still using smbmount on Debian or Ubuntu are doing so with
servers that are supported by cifs.  For those that aren't, there is no
smooth transition possible with or without a wrapper; for everyone else,
anything that we fail to map in mount.smbfs is a bug that we can and should
fix.

> WHAT CAN BE DONE?:
>  - leaving smbfs (and related stuff) in place

I don't think either Debian or Ubuntu (or upstream) want to do this. The
smbfs driver and userspace tools both have numerous issues that will never
be worked on; it's not reasonable to expect this driver to be supported
indefinitely.

>  - inform all distro maintainers about this
>  - drop legacy mount support completely (!?)

If you mean dropping this support from the cifs driver, that doesn't make
any sense at all.  *No one* is supporting the smbfs driver; it has
significant bugs that are never going to be worked on, and based on the bug
reports I've seen over the years in Debian, I think it's even suffered from
some pretty hefty bit rot in the kernel.

It would be a shame to have the cifs maintainers deny support for legacy SMB
servers.  It's clear to me that even if cifs doesn't yet support all servers
perfectly, *users* are getting much better support for problems with cifs
than they have in years for smbfs.

>  - build 2 versions of cifs vfs
>    - one without CONFIG_CIFS_WEAK_PW_HASH
>    - one with CONFIG_CIFS_WEAK_PW_HASH

Why?  LANMAN and plaintext are still disabled by default at runtime when
CONFIG_CIFS_WEAK_PW_HASH is enabled.  I can't see any reason to build *two*
copies of cifs.ko when this is perfectly selectable at runtime.

So I think the best option is really:

  - enable CONFIG_CIFS_WEAK_PW_HASH by default upstream

Cheers,
-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org