2008-06-17 21:36:35

by [email protected]

[permalink] [raw]
Subject: Re: [RFC] new client gssd upcall

On Mon, Jun 16, 2008 at 10:28:59AM -0400, Jeff Layton wrote:
> On Fri, 13 Jun 2008 18:50:37 -0400
> "J. Bruce Fields" <[email protected]> wrote:
>
> > The client needs a new more estensible text-based upcall to gssd, to
> > make it easier to support some features that are needed for new krb5
> > enctypes, for callbacks, etc.
> >
> > We will have to continue to support the old upcall for backwards
> > compatibility with older gssd's. To simplify upgrades, as well as
> > testing and debugging, it would help if we can upgrade gssd without
> > having to choose at boot (or module-load) time whether we want the new
> > or the old upcall.
> >
> > That means that when gssd opens an rpc upcall pipe, we'd like to just
> > start using whichever version it chose immediately--ideally without
> > having to wait the 30 seconds that it would normally take for upcalls
> > already queued on the wrong upcall pipe to time out.
> >
> > The following patches do that by queueing the upcalls on whichever of
> > the two upcall pipes (the new one and the old one) that somebody holds
> > open. If nobody's opened anything yet, then upcalls are provisionally
> > queued on the new pipe. I add a pipe_open method to allow the gss code
> > to keep track of which pipe is open, to prevent anyone from attempting
> > to open both pipes at once, and to cancel any upcalls that got queued to
> > the wrong pipe.
> >
> > I did some minimal testing with the old upcall, but haven't tested the
> > new upcall yet. (Olga, could you do that?) So this is just an RFC at
> > this point.
> >
> > --b.
>
> Has any thought been given to moving all of the rpc_pipefs upcalls to use
> the keyctl API that David Howells did? It seems like that would be better
> suited to this sort of application than rpc_pipefs...

I haven't looked at it. I've just assumed that since Trond and Kevin
have both looked at both API's, then there must be some good reason
we're not using it....

--b.


2008-06-17 22:00:00

by Myklebust, Trond

[permalink] [raw]
Subject: Re: [RFC] new client gssd upcall

On Tue, 2008-06-17 at 17:36 -0400, J. Bruce Fields wrote:
> On Mon, Jun 16, 2008 at 10:28:59AM -0400, Jeff Layton wrote:
> > On Fri, 13 Jun 2008 18:50:37 -0400
> > "J. Bruce Fields" <[email protected]> wrote:
> >
> > > The client needs a new more estensible text-based upcall to gssd, to
> > > make it easier to support some features that are needed for new krb5
> > > enctypes, for callbacks, etc.
> > >
> > > We will have to continue to support the old upcall for backwards
> > > compatibility with older gssd's. To simplify upgrades, as well as
> > > testing and debugging, it would help if we can upgrade gssd without
> > > having to choose at boot (or module-load) time whether we want the new
> > > or the old upcall.
> > >
> > > That means that when gssd opens an rpc upcall pipe, we'd like to just
> > > start using whichever version it chose immediately--ideally without
> > > having to wait the 30 seconds that it would normally take for upcalls
> > > already queued on the wrong upcall pipe to time out.
> > >
> > > The following patches do that by queueing the upcalls on whichever of
> > > the two upcall pipes (the new one and the old one) that somebody holds
> > > open. If nobody's opened anything yet, then upcalls are provisionally
> > > queued on the new pipe. I add a pipe_open method to allow the gss code
> > > to keep track of which pipe is open, to prevent anyone from attempting
> > > to open both pipes at once, and to cancel any upcalls that got queued to
> > > the wrong pipe.
> > >
> > > I did some minimal testing with the old upcall, but haven't tested the
> > > new upcall yet. (Olga, could you do that?) So this is just an RFC at
> > > this point.
> > >
> > > --b.
> >
> > Has any thought been given to moving all of the rpc_pipefs upcalls to use
> > the keyctl API that David Howells did? It seems like that would be better
> > suited to this sort of application than rpc_pipefs...
>
> I haven't looked at it. I've just assumed that since Trond and Kevin
> have both looked at both API's, then there must be some good reason
> we're not using it....

Kevin has spent quite some time working on the keyring support, but as
far as I understand the amount of time he can continue to spend working
for CITI has recently been heavily reduced...

--
Trond Myklebust
Linux NFS client maintainer

NetApp
[email protected]
http://www.netapp.com

2008-06-17 22:09:30

by [email protected]

[permalink] [raw]
Subject: Re: [RFC] new client gssd upcall

On Tue, Jun 17, 2008 at 05:59:29PM -0400, Trond Myklebust wrote:
> On Tue, 2008-06-17 at 17:36 -0400, J. Bruce Fields wrote:
> > On Mon, Jun 16, 2008 at 10:28:59AM -0400, Jeff Layton wrote:
> > > Has any thought been given to moving all of the rpc_pipefs upcalls to use
> > > the keyctl API that David Howells did? It seems like that would be better
> > > suited to this sort of application than rpc_pipefs...
> >
> > I haven't looked at it. I've just assumed that since Trond and Kevin
> > have both looked at both API's, then there must be some good reason
> > we're not using it....
>
> Kevin has spent quite some time working on the keyring support, but as
> far as I understand the amount of time he can continue to spend working
> for CITI has recently been heavily reduced...

Hm, but I thought that you'd both decided that the gssd upcalls would
end up coexisting with the upcalls in any case?

If there's a chance we might end up replacing the gssd upcalls entirely,
then--while I don't want to stretch out this one task
indefinitely--still it might be worth my time to go take a look at the
keyctl API's Jeff mentions.

--b.

2008-06-18 11:52:13

by Jeff Layton

[permalink] [raw]
Subject: Re: [RFC] new client gssd upcall

On Tue, 17 Jun 2008 18:09:18 -0400
"J. Bruce Fields" <[email protected]> wrote:

> On Tue, Jun 17, 2008 at 05:59:29PM -0400, Trond Myklebust wrote:
> > On Tue, 2008-06-17 at 17:36 -0400, J. Bruce Fields wrote:
> > > On Mon, Jun 16, 2008 at 10:28:59AM -0400, Jeff Layton wrote:
> > > > Has any thought been given to moving all of the rpc_pipefs upcalls to use
> > > > the keyctl API that David Howells did? It seems like that would be better
> > > > suited to this sort of application than rpc_pipefs...
> > >
> > > I haven't looked at it. I've just assumed that since Trond and Kevin
> > > have both looked at both API's, then there must be some good reason
> > > we're not using it....
> >
> > Kevin has spent quite some time working on the keyring support, but as
> > far as I understand the amount of time he can continue to spend working
> > for CITI has recently been heavily reduced...
>
> Hm, but I thought that you'd both decided that the gssd upcalls would
> end up coexisting with the upcalls in any case?
>
> If there's a chance we might end up replacing the gssd upcalls entirely,
> then--while I don't want to stretch out this one task
> indefinitely--still it might be worth my time to go take a look at the
> keyctl API's Jeff mentions.
>

If you're interested, there are several examples of upcalls that use
this API in CIFS. I used it for the SPNEGO/Kerberos stuff that I did
there several months ago. It's pretty easy to use and can handle a
fairly large payload if needed.

When it does the upcall, it runs a particular program, so there's no
need for a running daemon. That might be considered a good thing here
since it may be one less thing that a user has to remember to have
running...

--
Jeff Layton <[email protected]>

2008-06-19 15:37:18

by Olga Kornievskaia

[permalink] [raw]
Subject: Re: [RFC] new client gssd upcall



Trond Myklebust wrote:
> On Tue, 2008-06-17 at 17:36 -0400, J. Bruce Fields wrote:
>
>> On Mon, Jun 16, 2008 at 10:28:59AM -0400, Jeff Layton wrote:
>>
>>> On Fri, 13 Jun 2008 18:50:37 -0400
>>> "J. Bruce Fields" <[email protected]> wrote:
>>>
>>>
>>>> The client needs a new more estensible text-based upcall to gssd, to
>>>> make it easier to support some features that are needed for new krb5
>>>> enctypes, for callbacks, etc.
>>>>
>>>> We will have to continue to support the old upcall for backwards
>>>> compatibility with older gssd's. To simplify upgrades, as well as
>>>> testing and debugging, it would help if we can upgrade gssd without
>>>> having to choose at boot (or module-load) time whether we want the new
>>>> or the old upcall.
>>>>
>>>> That means that when gssd opens an rpc upcall pipe, we'd like to just
>>>> start using whichever version it chose immediately--ideally without
>>>> having to wait the 30 seconds that it would normally take for upcalls
>>>> already queued on the wrong upcall pipe to time out.
>>>>
>>>> The following patches do that by queueing the upcalls on whichever of
>>>> the two upcall pipes (the new one and the old one) that somebody holds
>>>> open. If nobody's opened anything yet, then upcalls are provisionally
>>>> queued on the new pipe. I add a pipe_open method to allow the gss code
>>>> to keep track of which pipe is open, to prevent anyone from attempting
>>>> to open both pipes at once, and to cancel any upcalls that got queued to
>>>> the wrong pipe.
>>>>
>>>> I did some minimal testing with the old upcall, but haven't tested the
>>>> new upcall yet. (Olga, could you do that?) So this is just an RFC at
>>>> this point.
>>>>
>>>> --b.
>>>>
>>> Has any thought been given to moving all of the rpc_pipefs upcalls to use
>>> the keyctl API that David Howells did? It seems like that would be better
>>> suited to this sort of application than rpc_pipefs...
>>>
>> I haven't looked at it. I've just assumed that since Trond and Kevin
>> have both looked at both API's, then there must be some good reason
>> we're not using it....
>>
>
> Kevin has spent quite some time working on the keyring support, but as
> far as I understand the amount of time he can continue to spend working
> for CITI has recently been heavily reduced...
>
>
I don't think we ever considered replacing NFS's client upcall
mechanism. Why would we scrap a perfectly good implementation that Trond
keeps on improving and making better?


2008-06-19 15:49:51

by Jeff Layton

[permalink] [raw]
Subject: Re: [RFC] new client gssd upcall

On Thu, 19 Jun 2008 11:37:17 -0400
Olga Kornievskaia <[email protected]> wrote:

>
>
> Trond Myklebust wrote:
> > On Tue, 2008-06-17 at 17:36 -0400, J. Bruce Fields wrote:
> >
> >> On Mon, Jun 16, 2008 at 10:28:59AM -0400, Jeff Layton wrote:
> >>
> >>> On Fri, 13 Jun 2008 18:50:37 -0400
> >>> "J. Bruce Fields" <[email protected]> wrote:
> >>>
> >>>
> >>>> The client needs a new more estensible text-based upcall to gssd, to
> >>>> make it easier to support some features that are needed for new krb5
> >>>> enctypes, for callbacks, etc.
> >>>>
> >>>> We will have to continue to support the old upcall for backwards
> >>>> compatibility with older gssd's. To simplify upgrades, as well as
> >>>> testing and debugging, it would help if we can upgrade gssd without
> >>>> having to choose at boot (or module-load) time whether we want the new
> >>>> or the old upcall.
> >>>>
> >>>> That means that when gssd opens an rpc upcall pipe, we'd like to just
> >>>> start using whichever version it chose immediately--ideally without
> >>>> having to wait the 30 seconds that it would normally take for upcalls
> >>>> already queued on the wrong upcall pipe to time out.
> >>>>
> >>>> The following patches do that by queueing the upcalls on whichever of
> >>>> the two upcall pipes (the new one and the old one) that somebody holds
> >>>> open. If nobody's opened anything yet, then upcalls are provisionally
> >>>> queued on the new pipe. I add a pipe_open method to allow the gss code
> >>>> to keep track of which pipe is open, to prevent anyone from attempting
> >>>> to open both pipes at once, and to cancel any upcalls that got queued to
> >>>> the wrong pipe.
> >>>>
> >>>> I did some minimal testing with the old upcall, but haven't tested the
> >>>> new upcall yet. (Olga, could you do that?) So this is just an RFC at
> >>>> this point.
> >>>>
> >>>> --b.
> >>>>
> >>> Has any thought been given to moving all of the rpc_pipefs upcalls to use
> >>> the keyctl API that David Howells did? It seems like that would be better
> >>> suited to this sort of application than rpc_pipefs...
> >>>
> >> I haven't looked at it. I've just assumed that since Trond and Kevin
> >> have both looked at both API's, then there must be some good reason
> >> we're not using it....
> >>
> >
> > Kevin has spent quite some time working on the keyring support, but as
> > far as I understand the amount of time he can continue to spend working
> > for CITI has recently been heavily reduced...
> >
> >
> I don't think we ever considered replacing NFS's client upcall
> mechanism. Why would we scrap a perfectly good implementation that Trond
> keeps on improving and making better?
>

Because it's less code that we have to maintain. rpc_pipefs certainly works
(and works fairly well), but we have so many upcall mechanisms in the
kernel already. keyctl also has some nice features (automated cache
timeouts, granular security, etc), and was designed with this sort of use
in mind.

I'm not saying that we absolutely need to scrap rpc_pipefs, but considering
alternatives may mean less work for us all in the long run.

--
Jeff Layton <[email protected]>