[nfsv4] RFC: new optional attribute related to owner-override

[Rick Macklem <[e-mail]>]

I am thinking of adding this attribute to my draft, but thought
I'd ask for comments first.

This one would be per server (for a given client's ClientID) and
would apply to the following operations:
Read, Write, Setattr-of-size, Allocate, Deallocate, Copy,
Open(Claim_delegate_cur/Claim_deleg_cur_fh)

I am thinking of a tri-state attribute:
1 - A permission check is done via mode or ACL for each of the
     above operations.
2 - The owner of the file is permitted to perform the above operations.
     For non-owner requests, a permission check is done via mode or ACL
     for each of the above operations.
3 - The operation is permitted, if an appropriate valid stateid(s) (not
     special stateid(s)) is provided, plus:
    - The client has been peer authenticated.
    - At least integrity protection is being applied to the connection the
      request is received on.
    (Appropriate stateid would be defined, but for this discussion, I think
     what is appropriate should be fairly obvious. Note that a lock_stateid
     is always associated with an open_stateid via open_to_lock_stateid and
     the open_stateid is for Read, Write, or Both access.)

A server would not be required to support all 3 attribute values and
would return NFS4ERR_INVAL for any value not supported when a
Setattr of the attribute is attempted.

The setting would apply to the ClientID implied by the Sequence
operation for the compound the operation is in.

The object would be to both document what the serve implements
and to allow a client to select a preference, for servers that support
more than one of the above 3 attribute values.
(Probably an enumerated type when done in XDR.)

So, what do others think? rick