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

[Rick Macklem <[e-mail]>]

On Thu, Jul 25, 2024 at 12:36 PM David Noveck <[e-mail]> wrote:

>
>
> On Thursday, July 25, 2024, Chuck Lever III <[e-mail]>
> wrote:
>
>>
>>
>> > On Jul 25, 2024, at 9:44 AM, Rick Macklem <[e-mail]>
>> wrote:
>> >
>> > Christoph pointed out to me that having multiple ACLs on a file is not
>> > reasonable.  The draft I am writing will require a server to only
>> support
>> > one ACL model/file. (I think it needs to be a server choice and could be
>> > indicated to the client by which attributes are supported for the fiile.
>> > (This is related to the last point.  I'll leave the rest for others.)
>>
>> 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.
>
If you are referring to the granularity of whether a
NFSv4 ACL or POSIX draft ACL is applied, I do not see
a problem with "per file" granularity, which is what I
had planned for the draft I am writing (in progress).
(My limited vision comes from the fact that FreeBSD uses
a "per file system" mount option to define which ACL model
is used.)

However, if you are suggestion that a file object could
have both a NFSv4 ACL and a POSIX draft ACL, then I do
envision problems.
--> How would the server check access?
    - By checking both ACLs and only allow access if both
      ACLs allowed access?
      --> That would cause confusion for users on clients
          that only see one of the ACLs, when the ACL the
          client sees allows access, but the server replies
          NFS4ERR_ACCES, since the other ACL does not allow
          access.

rick



>
>
>>
>> > It would be nice if, somehow, the Linux folk could determine how often
>> > the mapped NFSv4 ACLs are used on the Linux NFSv4 servers?
>>
>> As far as I am aware, NFSD does not use mapped ACLs, but I
>> haven't done an in-depth look.
>>
>>
>> --
>> Chuck Lever
>>
>>
>>