[Labeled-nfs] Current development prototype patches.

[Casey Schaufler]

--- Trond Myklebust <trond.myklebust at fys.uio.no> wrote:

> On Mon, 2007-08-06 at 12:33 -0700, Casey Schaufler wrote:
> > --- Trond Myklebust <trond.myklebust at fys.uio.no> wrote:
> > 
> > > On Sat, 2007-08-04 at 19:51 +0100, Christoph Hellwig wrote:
> > > > On Sat, Aug 04, 2007 at 11:38:06AM -0700, Casey Schaufler wrote:
> > > > > I agree. EAs over NFS are not very hard. Have you seen the SGI
> published
> > > > > xattr extension? It's not large or particularly complex, and it has 
> > > > > about 10 years exposure in the Unix environment.
> > > > 
> > > > It's extremly nice.  And SGI even released the xdr en/decoding files
> > > > under GPL a while ago.  A lot nicer than either the SUN NFSv3 ACL
> > > > extensions or the whole subfile bullshit added to NFSv4.
> > > 
> > > Ugh. Yet another RPC sideband protocol?
> > 
> > Your point being?
> 
> That it should hardly be breaking news to anyone that this type of
> sideband protocol sucks: the NLM, quota and the various ACL sideband
> protocols provide ample evidence for why.
> 
> They are firewall-unfriendly: in particular, they usually require
> ungainly extensions to the basic RPC protocol in the form of the
> portmapper. We already got rid of that crap for NFSv4.
> 
> They add significant latency: The fact that you have a sideband protocol
> instead of integrating it into the protocol means that you cannot use
> optimisations such as NFSv4's COMPOUND to send the EA request as part of
> the LOOKUP/OPEN/READDIR/whatever operation that you want to check the
> protection status of. Instead you are forced to make another
> (synchronous!) RPC request to the server in order to get the information
> you need.
> Your processes may be "safe", but they will run like treacle.
> 
> They add complexity: they are not part of the protocol, yet they add
> conditions to the protocol. For instance, there is the issue of the
> interaction of EAs with delegations, mandatory locks, share modes,...
> 
> All in all, they are a band-aid at best, and a bloody nuisance at worst.

Ok, so you're right. What is your recommendation on getting xattrs
into a "real" protocol before they ship me off to the California
Home for the Bewildered? We implemented the SGI xattr extension ten
years ago and no one has done boo in the "real" protocol space the
entire time since, it's still the best available implementation. I
am supporting the work here in hopes that even if it turns out not
to my liking it may at least break the current technology logjam.



Casey Schaufler
casey at schaufler-ca.com