Messages in this thread | | | Date | Thu, 30 Mar 2006 10:15:21 -0600 | From | "Serge E. Hallyn" <> | Subject | Re: [RFC] Virtualization steps |
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Quoting Stephen Smalley (sds@tycho.nsa.gov): > On Thu, 2006-03-30 at 08:32 -0600, Serge E. Hallyn wrote: > > Frankly I thought, and am still not unconvinced, that containers owned > > by someone other than the system owner would/should never want to load > > their own LSMs, so that this wasn't a problem. Isolation, as Chris has > > mentioned, would be taken care of by the very nature of namespaces. > > > > There are of course two alternatives... First, we might want to allow the > > machine admin to insert per-container/per-namespace LSMs. To support > > this case, we would need a way for the admin to tag a container some way > > identifying it as being subject to a particular set of security_ops. > > > > Second, we might want container admins to insert LSMs. In addition to > > a straightforward way of tagging subjects/objects with their container, > > we'd need to implement at least permissions for "may insert global LSM", > > "may insert container LSM", and "may not insert any LSM." This might be > > sufficient if we trust userspace to always create full containers. > > Otherwise we might want to support meta-policy along the lines of "may > > authorize ptrace and mount hooks only", or even "not subject to the > > global inode_permission hook, and may create its own." (yuck) > > > > But so much of this depends on how the namespaces/containers end up > > being implemented... > > FWIW, SELinux now has a notion of a type hierarchy in its policy, so the > root admin can carve out a portion of the policy space and allow less > privileged admins to then define sub-types that are strictly constrained > by what was allowed to the parent type by the root admin. This is > handled in userspace, with the policy mediation performed by a userspace > agent (daemon, policy management server), which then becomes the focal > point for all policy loading.
Yes, my first response (which I cancelled) mentioned this as a possible solution.
The global admin could assign certain max privileges to 'container_b'. The admin in container_b could create container_b.root_t, container_b.user_t, etc, which would be limited by the container_b max perms.
Presumably the policy daemon, running in container 0, could accept input from a socket from container 2, labeled appropriately automatically ensuring that all types created by the policy in container 2 are prefixed with container_b, and doing the obvious restrictions.
Or something like that :)
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