Re: [PATCH 0/3] keys: play nicely with user namespaces

From: David Howells <dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: "Serge E. Hallyn" <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
Cc: dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
	Linux Containers
	<containers-qjLDD68F18O7TbgM5vRIOg@public.gmane.org>,
	"Eric W. Biederman"
	<ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
Subject: Re: [PATCH 0/3] keys: play nicely with user namespaces
Date: Fri, 12 Dec 2008 12:51:34 +0000	[thread overview]
Message-ID: <3507.1229086294@redhat.com> (raw)
In-Reply-To: <20081211232323.GA8343-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>

Serge E. Hallyn <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> wrote:

> so here is a first attempt at getting keys and uid namespaces
> to play nice.  The semantics need some discussion.  As I recall
> Eric and yourself appeared to agree that some keyrings should
> be inherited into child user namespaces.

Ummm...  If keys are effectively a per-user-namespace resource, then they
can't be shared between namespaces.  We could either duplicate all the keys
and keyrings, or we could just start afresh.  The latter is certainly the
easiest.

> I segragate them cleanly bc that appears to be the simplest thing to do
> especially given the use of i.e. lookup_by_name("uid.500").

Sounds reasonable.

> IMO it shouldn't be a big problem - userspace can always list keys it wants
> into a file, start a new user namespace, then re-read them out of the
> tempfile...

Not so.  You aren't necessarily permitted to read a key - the read function
has to be supported by the key type for a start, and then you have to pass all
the security checks.

David