isolate selinux_enforcing

On 3/13/2017 12:06 AM, James Morris wrote:

On Thu, 9 Mar 2017, Eric W. Biederman wrote:

quoted

My expectation is that a container would run as essentially all one
label from a global perspective.

Keep in mind that a different classes of objects may have distinct 
labeling in SELinux.  e.g. a process and a file typically have different 
labels (say, sshd_t vs. sshd_key_t).

Also, I think you will want to have the global namespace always use the 
original security labels.  If accessing an object from outside the 
container, the original global policy should always apply.  Really, this 
needs to be an invariant property.

I'd suggest implementing an orthogonal 2nd set of security labels which 
are only ever used within the container.

The work that's been done for Smack namespaces

	https://lwn.net/Articles/652320

may come in handy during during your deliberations for
SELinux. Conceptually you can create aliases for your
base labels, and use those within the container. Very
much like the UID mapping of user namespaces. Labels that
don't have an alias can't be accessed within the namespace.

quoted

To implement this would require a revision on the selinux labels xattrs
so that they can be marked as being part of a container...  But having
the labels look ordinary inside the container.

We almost have a patch that implements something like that for the
capability xattr.

It'll be interesting to see.

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