[nfsv4] Re: Our different approaches to draft POSIX ACL support in NFSv4

[David Noveck <[e-mail]>]

On Friday, July 26, 2024, Chuck Lever III <[e-mail]> wrote:

>
>
> > On Jul 25, 2024, at 3:36 PM, David Noveck <[e-mail]> wrote:
> >
> > On Thursday, July 25, 2024, Chuck Lever III <[e-mail]>
> wrote:
> >
> >> I agree there should be one per file,
> >
> > Definitely.
> >
> >> and that the server's
> >> local file system should determine which type of ACL it can
> >> support.
> >
> > I would think it determines the set of types  it  an support.  This can
> be ofen will be a singleton or the null set.
> >
> >> (I don't envision a scenario where one file system
> >> could support multiple types of ACLs).
> >>
> > I consider it unfortunate that your vision is so limited.
> >
> > I expect to face the issue in the near future since Netapp supports a
> considerable portion of the NFSv4 ACL model and will want to support the
> draft POSIX ACL.
> >
> > I don't think it is reasonable to tell users that they have to get rid
> of their existing ACLs in order to allow them to use draft POSIX ACLs.
>
> Hopefully this can shed a little light on the use case
> that Linux NFSD might prefer -- I'm not denigrating any
> other usage scenarios.
>
> For Linux NFSD, its local file systems can store only
> POSIX ACLs.
>
> In order to provide broad compatibility with existing
> and new clients, I'm thinking that NFSD will provide
> GET/SETATTR capabilities that allow clients to see both
> a mapped NFSv4 ACL and a POSIX ACL per file; the mapped
> ACL will be created from the stored POSIX ACL to satisfy
> GETATTR requests, and access authorization decisions will
> be based on the stored POSIX ACL, as I believe NFSD does
> today.


As a said before, the sacl case need to be dealt with also.  Since there
are no POSIX sacls, this winds up meaning that the allow and alarm ACEs are
only part of the NFSv4 ACL model.

Probably Linux clients and servers will not deal with such ACEs.

BTW, this is another illustration of how ludicrous it was to call such
attributes "RECOMMENDED".  Switching it to OPTIONAL is a move toward sanity.


>
> NFSD will map incoming NFSv4 ACLs to POSIX ACLs before
> storing them.


You need to deal with the cae of those that are not mappable.  There are
some suggestions about this in acls-05.


>
>  Storing either type of ACL will wholly
> replace the POSIX ACL that is already there.


Yes.


>
>
> --
> Chuck Lever
>
>
>