Re: [nfsv4] Chapter 12 for next rfc3530bis

"J. Bruce Fields" <bfields@fieldses.org> Tue, 12 October 2010 19:04 UTC

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Date: Tue, 12 Oct 2010 15:05:52 -0400
From: "J. Bruce Fields" <bfields@fieldses.org>
To: david.noveck@emc.com
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Subject: Re: [nfsv4] Chapter 12 for next rfc3530bis
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On Tue, Oct 12, 2010 at 02:47:40PM -0400, david.noveck@emc.com wrote:
> You as the server can enforce it by simply checking whether it is UTF-8
> and returning INVAL if it isn't.

Alas, no, if I get a getattr for the owner of a file, find the file is
owned by uid 8569, look up 8569 and it's somebody non-ascii and
non-utf8, my choices are:

	- Return an error, or claim not to support the owner attribute
	  on this file.
	- Attempt to guess the encoding and map to utf-8 before
	  returning.
	- Just return the username as it is.

And if I pick 3 (and it's what the code would do now, and seems the
least of evils), and the client tries to send the same name back to me
in a setattr, I can't see returning INVAL.

I could try to avoid getting into the whole situation in the first place
by forbidding those names.  That's not really up to me.

In the end I guess this just means I'll be violating the spec in some
(probably very unlikely?) cases.  Solaris too I bet, if it has
historically allowed such usernames.  It won't keep me up at night.

--b.

> The client is going to have some understanding of what it is being
> presented with and certainly can map an o-umlaut for example, to the
> UTF-8 version of that which is two bytes.  It is supposed to send UTF-8.
> 
> 
> -----Original Message-----
> From: J. Bruce Fields [mailto:bfields@fieldses.org] 
> Sent: Tuesday, October 12, 2010 2:29 PM
> To: Noveck, David
> Cc: Black, David; jlentini@netapp.com; nfsv4@ietf.org
> Subject: Re: [nfsv4] Chapter 12 for next rfc3530bis
> 
> On Tue, Oct 12, 2010 at 02:12:55PM -0400, david.noveck@emc.com wrote:
> > On Tue, Oct 12, 2010 at 01:07:59PM -0400, bfields wrote:
> > > I just want to make sure I'm getting into the business of mapping
> > 
> > (I meant to have a "not" there!)
> > 
> > > non-ascii non-utf8 usernames....
> > 
> > UVMUST says it MUST be UTF-8.  So if you get into the business of
> > mapping non-ascii non-utf8, you are non-compliant and you have only
> > yourself to blame for having to map stuff that you aren't supposed to
> > have accepted in the first place. 
> 
> I have some control over nfsd, but none over useradd.  If there are
> people out there with /etc/passwd's containing non-utf8 non-ascii
> usernames then the only way I'd see to enforce a MUST of utf-8 would be
> by taking a stab at what encoding they're using and then mapping to and
> from utf-8.  No thanks!
> 
> Hm, but non-ascii usernames can't be used in email addresses, can they?
> So maybe we'll never see them in practice.
> 
> --b.
>