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Message-ID: <2819.1457451134@warthog.procyon.org.uk>
Date: Tue, 08 Mar 2016 15:32:14 +0000
From: David Howells <dhowells@...hat.com>
To: Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc: dhowells@...hat.com, linux-security-module@...r.kernel.org,
keyrings@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 11/12] certs: Add a secondary system keyring that can be added to dynamically [ver #2]
Mimi Zohar <zohar@...ux.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
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