Re: [RFC PATCH 5/8] KEYS: exec request-key within the requesting task's init namespace

From: "J. Bruce Fields" <bfields@fieldses.org>
To: Benjamin Coddington <bcodding@redhat.com>
Cc: Ian Kent <ikent@redhat.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	David Howells <dhowells@redhat.com>,
	Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Oleg Nesterov <onestero@redhat.com>,
	Trond Myklebust <trond.myklebust@primarydata.com>,
	Al Viro <viro@ZenIV.linux.org.uk>,
	Jeff Layton <jeff.layton@primarydata.com>
Subject: Re: [RFC PATCH 5/8] KEYS: exec request-key within the requesting task's init namespace
Date: Tue, 24 Feb 2015 10:33:29 -0500	[thread overview]
Message-ID: <20150224153329.GA2415@fieldses.org> (raw)
In-Reply-To: <alpine.OSX.2.19.9992.1502231654580.80359@planck.local>

On Mon, Feb 23, 2015 at 05:22:12PM -0800, Benjamin Coddington wrote:
> That sounds a lot closer to some of the work I've been doing to see if I can
> come up with a way to solve the "where's the namespace I need?" problem.
> 
> I agree with Greg's very early comments that the easiest way to determine
> which namespace context a process should use is to keep it as a copy of
> the task -- and the place that copy should be done is fork().

So you're suggesting that the key_agent could be that copy?  But:

> ... If not, then the calling process itself is forked/execve-ed into a
> new persistent key_agent that is installed on the calling process'
> keyrings just like a key, and with the same lifetime and GC
> expectations of a key.
> 
> A key_agent is a user-space process...

If the key_agent can die before it's needed, then we have to keep around
some other context information to allow regenerating a new one.  So what
is that piece of information?  Aren't we back where we started?

--b.