Re: [nfsv4] Fwd: I-D Action: draft-ietf-nfsv4-integrity-measurement-03.txt

[Chuck Lever <[e-mail]>]

Hi Dave-

> On Nov 9, 2018, at 5:52 AM, David Noveck <[e-mail]> wrote:
> 
> > I do want to have multiple FPI
> > blobs per file. 
> 
> If so, then this desire could be accommodated more simply than by
> allowing each such blob type (fpv_type) to be invidually settable
> and retrievable as is suggested in -03.  The existing NFSv4 attribute
> model would need substantial change to accommodate that.

Modifying one at a time doesn't seem impractical, but
getting all of them at once would eliminate the need for
enumeration.


> I think the best way to provide for the possibility of multiple blobs would 
> be to make the provenace  attribute an array of blobs.   I think the
> following would work but I might have messed up the typdef syntax.
> 
> typedef file_prov4              fattr4_file_provenance[];

The problem with this design is it makes it impossible for
the client to predict how large its RPC Reply buffer needs
to be.


> Those who sign content will need to generate all the blobs they want
> to support.  I don't see why setting each blob needs to a separate operation.

Because they might be set at different points in a file's
lifetime by different tools.


> Assesors, could get the entire blob set and fairly easily find the blob(s) they want to access.
>  
> > IMA has one for file content, and another one
> > for file attributes (the EVM blob). Both can exist at the same
> > time. 
> 
> OK.
> 
> > I'm specifying only the IMA blob for NFS at this time, as
> > explained in a prior email, 
> 
> As I understood it, wou were not actually specifying it but were 
> simply directing people to a description.   I can't recall the details, but
> I recall some complexity about whether that description was actually
> a specfication.

What I meant was, I'm requesting from IANA just the IMA
container. The EVM container will wait for another
document.


> > but you should assume that more blobs
> > will be coming in the future.  
> 
> They might and implemeters will make their own decisions about how much space to allocate to store potenial blobs.


--
Chuck Lever