linux-kernel - Re: [PATCH v4 00/12] Enroll kernel keys thru MOK

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Message-ID: <18c0a9ca6b3ab8103e3b9270a6f59539787f6e12.camel@kernel.org>
Date:   Wed, 01 Sep 2021 07:34:41 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Nayna <nayna@...ux.vnet.ibm.com>,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Eric Snowberg <eric.snowberg@...cle.com>,
        David Howells <dhowells@...hat.com>
Cc:     keyrings@...r.kernel.org,
        linux-integrity <linux-integrity@...r.kernel.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <davem@...emloft.net>,
        James Morris <jmorris@...ei.org>,
        "Serge E . Hallyn" <serge@...lyn.com>, keescook@...omium.org,
        gregkh@...uxfoundation.org, torvalds@...ux-foundation.org,
        scott.branden@...adcom.com, weiyongjun1@...wei.com,
        nayna@...ux.ibm.com, ebiggers@...gle.com, ardb@...nel.org,
        Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
        lszubowi@...hat.com, linux-kernel@...r.kernel.org,
        linux-crypto@...r.kernel.org,
        linux-security-module@...r.kernel.org, pjones@...hat.com,
        "konrad.wilk@...cle.com" <konrad.wilk@...cle.com>,
        Patrick Uiterwijk <patrick@...terwijk.org>
Subject: Re: [PATCH v4 00/12] Enroll kernel keys thru MOK

On Fri, 2021-08-27 at 16:44 -0400, Nayna wrote:
> On 8/25/21 6:27 PM, James Bottomley wrote:
> > On Thu, 2021-08-26 at 01:21 +0300, Jarkko Sakkinen wrote:
> > > On Tue, 2021-08-24 at 10:34 -0400, Mimi Zohar wrote:
> > > > > > > Jarkko, I think the emphasis should not be on "machine" from
> > > > > > > Machine Owner Key (MOK), but on "owner".  Whereas Nayna is
> > > > > > > focusing more on the "_ca" aspect of the name.   Perhaps
> > > > > > > consider naming it "system_owner_ca" or something along those
> > > > > > > lines.
> > > > > > What do you gain such overly long identifier? Makes no sense.
> > > > > > What is "ca aspect of the name" anyway?
> > > > > As I mentioned previously, the main usage of this new keyring is
> > > > > that it should contain only CA keys which can be later used to
> > > > > vouch for user keys loaded onto secondary or IMA keyring at
> > > > > runtime. Having ca in the  name like .xxxx_ca, would make the
> > > > > keyring name self-describing. Since you preferred .system, we can
> > > > > call it .system_ca.
> > > > Sounds good to me.  Jarkko?
> > > > 
> > > > thanks,
> > > > 
> > > > Mimi
> > > I just wonder what you exactly gain with "_ca"?
> > Remember, a CA cert is a self signed cert with the CA:TRUE basic
> > constraint.  Pretty much no secure boot key satisfies this (secure boot
> > chose deliberately NOT to use CA certificates, so they're all some type
> > of intermediate or leaf), so the design seems to be only to pick out
> > the CA certificates you put in the MOK keyring.  Adding the _ca suffix
> > may deflect some of the "why aren't all my MOK certificates in the
> > keyring" emails ...
> 
> My understanding is the .system_ca keyring should not be restricted only 
> to self-signed CAs (Root CA). Any cert that can qualify as Root or 
> Intermediate CA with Basic Constraints CA:TRUE should be allowed. In 
> fact, the intermediate CA certificates closest to the leaf nodes would 
> be best.
> 
> Thanks for bringing up that adding the _ca suffix may deflect some of 
> the "why aren't all my MOK certificates in the keyring" emails.

What the heck is the pragamatic gain of adding such a suffix? Makes
zero sense.

/Jarkko