On Fri, 2007-11-30 at 09:48 -0500, Stephen Smalley wrote: > On Fri, 2007-11-30 at 09:38 -0500, Joshua Brindle wrote: > > Stephen Smalley wrote: > > > On Thu, 2007-11-29 at 18:24 -0500, Joshua Brindle wrote: > > > > > >> Stephen Smalley wrote: > > >> > > >>> On Thu, 2007-11-29 at 14:27 -0500, tmiller@xxxxxxxxxx wrote: > > >>> > > >>> > > >>>> This is a reworking of the peersid capability patch Joshua sent out > > >>>> a few weeks ago. This version requires added explicit declaration of > > >>>> capabilities in the policy. > > >>>> > > >>>> I've used the same strings that Paul's kernel diff used (there is > > >>>> currently just a single capability). > > >>>> > > >>>> Note that capability declarations are not limited to base.conf / > > >>>> policy.conf as we would like to eventually get rid of the base vs. module > > >>>> distinction. > > >>>> > > >>>> > > >>> Taking the union of the capabilities at link time seems worrisome to me. > > >>> I'd be more inclined to require equivalence or take the intersection. > > >>> > > >>> > > >>> > > >> I strongly disagree. My vision was to be able to add a capability to the > > >> policy by inserting a policy module that enables the capability (and has > > >> associated policy). Making them an intersection or equivalence would > > >> require one to update every single module just to add a capability (or > > >> at least update the base if it is considered authoritative, which I was > > >> also trying to avoid). > > >> > > > > > > Joshua - think about it. Let's say I write a policy module based on the > > > new peer checks, and my base module was written in terms of the old > > > network checks. Now I link them together and get a policy that tells > > > the kernel to use the new peer checks. Voila! My base policy breaks > > > horrendously. > > > > > That is why I said the module being inserted would have the associated > > policy. > > That seems to violate modularity/encapsulation. > > > I don't believe policyrep is going to have a concept of base so > > we'd just be delaying the inevitable by restricting it to base now. > > It isn't a base vs. non-base issue. You can certainly have every module > declare the capabilities it requires/expects. But taking the union is > unsafe. Module foo doesn't know what the rest of the modules on the > system expect or what rules they contain. > > Requiring equivalence is the safest approach. Another point to consider - switching capabilities might require not only adding new rules but also removing existing rules. Which a new module can't do, at least presently. -- Stephen Smalley National Security Agency -- This message was distributed to subscribers of the selinux mailing list. If you no longer wish to subscribe, send mail to majordomo@xxxxxxxxxxxxx with the words "unsubscribe selinux" without quotes as the message.
