Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley
	Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United
	Kingdom.
	Registered in England and Wales under Company Registration No. 3798903
From: David Howells <dhowells@redhat.com>
In-Reply-To: <1457449745.5321.141.camel@linux.vnet.ibm.com>
References: <1457449745.5321.141.camel@linux.vnet.ibm.com> <1457447480.5321.115.camel@linux.vnet.ibm.com> <1457402735.5321.14.camel@linux.vnet.ibm.com> <20160304150022.17121.34501.stgit@warthog.procyon.org.uk> <20160304150142.17121.56666.stgit@warthog.procyon.org.uk> <30699.1457442839@warthog.procyon.org.uk> <449.1457448192@warthog.procyon.org.uk>
To: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: dhowells@redhat.com, linux-security-module@vger.kernel.org,
        keyrings@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 11/12] certs: Add a secondary system keyring that can be added to dynamically [ver #2]
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <2818.1457451134.1@warthog.procyon.org.uk>
Content-Transfer-Encoding: 8BIT
Date: Tue, 08 Mar 2016 15:32:14 +0000
Message-ID: <2819.1457451134@warthog.procyon.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1588
Lines: 44

Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:

> > The problem boils down to a difficulty in concocting a name that describes a
> > complex situation that may change depending on the configuration.  I can make
> > it "restrict_link_by_any_system_trusted" if you'd prefer.
> > 
> > That's why I want "system trusted keyrings" to refer to the builtin and the
> > secondary - *and* an extra UEFI keyring if we grow one of those.  It's a
> > collection of related keyrings.
> 
> Sigh, this is the same discussion we've had for years.

No, it isn't.

> The UEFI keys should not be trusted to validate the certificates being added
> to the IMA keyring.

A machine-security (e.g. UEFI) keyring will conceivably live in
certs/system_keyring.c and only be enabled if CONFIG_SYSTEM_TRUSTED_KEYRINGS=y
and, say, CONFIG_MACHINE_TRUSTED_KEYRING=y.  I didn't say that IMA necessarily
has to use it.

What we need to do is define a set of functions allow IMA to get the
restrictions it wants, depending on configuration.  In the code I currently
have, I think we have those:

	restrict_link_reject
	restrict_link_by_builtin_trusted
	restrict_link_by_system_trusted

If you really want, I can add a restrict_link_for_ima in there, but I'd rather
not if IMA can use whichever of the above three most suits it.  How about:

	restrict_link_reject
	restrict_link_by_builtin_trusted
	restrict_link_by_builtin_or_secondary_trusted

> Neither should the keys on the secondary keyring, unless specifically IMA
> Kconfig enabled, be used to validate the certificates being added to the IMA
> keyring.

Yes.

David