Re: [RFC][Patch 2/6] integrity: fs hook placement

From: Stephen Smalley
Date: Thu Mar 08 2007 - 14:29:08 EST


On Thu, 2007-03-08 at 12:01 -0600, Serge E. Hallyn wrote:
> Quoting Chris Wright (chrisw@xxxxxxxxxxxx):
> > * Serge E. Hallyn (serue@xxxxxxxxxx) wrote:
> > > Are you objecting only to the duplication at the callsites, so that an
> > > fsnotify-type of consolidation of security and integrity hooks would be
> > > ok? Or are you complaining that the security_inode_setxattr and
> > > integrity_inode_setxattr hooks are too similar anyway, and integrity
> > > modules should just use some lsm hooks for anything which will be
> > > authoritative?
> >
> > It's duplication of callsites with many identical implementations
> > that's the problem.
>
> Yes it's ugly...
>
> But I guess it gets a point across :)
>
> > > (I could see an argument that integirty subsystem should be purely for
> > > measuring and hence its hooks should never return a value. Only hitch
> > > there is that if integrity subsystem hits ENOMEM it should be able to
> > > refuse the action...)
> >
> > Right, that's what I was expecting to see, just the measurement
> > infrastructure.
>
> So what you are saying is EVM would stay an LSM, with a cooperating
> integrity subsystem *just* doing measurements?
>
> That's kind of what i was expecting too, however that doesn't fit as
> well with the idea that an integrity subsystem prevents the need for lsm
> stacking. I think the idea was that evm would still be able to enforce
> integrity of selinux xattrs without it stack with selinux. So I can see
> where this approach came from.

The enforcement mechanism should be directly integrated into SELinux,
not stacked as a separate module.

--
Stephen Smalley
National Security Agency

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