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

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Message-ID: <bffb33a3-d5b5-f376-9d7d-706d38357d1a@linux.vnet.ibm.com>
Date:   Mon, 23 Aug 2021 16:48:11 -0400
From:   Nayna <nayna@...ux.vnet.ibm.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>,
        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,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        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 8/23/21 1:51 PM, Jarkko Sakkinen wrote:
> On Thu, 2021-08-19 at 13:32 -0400, Mimi Zohar wrote:
>> On Thu, 2021-08-19 at 09:23 -0600, Eric Snowberg wrote:
>>>> On Aug 19, 2021, at 7:10 AM, Mimi Zohar <zohar@...ux.ibm.com> wrote:
>>>>
>>>> On Thu, 2021-08-19 at 14:38 +0300, Jarkko Sakkinen wrote:
>>>>> On Wed, 2021-08-18 at 20:20 -0400, Eric Snowberg wrote:
>>>>>> Downstream Linux distros try to have a single signed kernel for each
>>>>>> architecture.  Each end-user may use this kernel in entirely different
>>>>>> ways.  Some downstream kernels have chosen to always trust platform keys
>>>>>> within the Linux trust boundary for kernel module signing.  These
>>>>>> kernels have no way of using digital signature base IMA appraisal.
>>>>>>
>>>>>> This series introduces a new Linux kernel keyring containing the Machine
>>>>>> Owner Keys (MOK) called .mok. It also adds a new MOK variable to shim.
>>>>> I would name it as ".machine" because it is more "re-usable" name, e.g.
>>>>> could be used for similar things as MOK. ".mok" is a bad name because
>>>>> it binds directly to a single piece of user space software.
>>>> Nayna previously said,
>>>>    "I believe the underlying source from where CA keys are loaded might vary
>>>>    based on the architecture (".mok" is UEFI specific.). The key part is
>>>>    that this new keyring should contain only CA keys which can be later
>>>>    used to vouch for user keys loaded onto IMA or secondary keyring at
>>>>    runtime. It would be good to have a "ca" in the name, like .xxxx-ca,
>>>>    where xxxx can be machine, owner, or system. I prefer .system-ca."
>>>>
>>>> The CA keys on the MOK db is simply the first root of trust being
>>>> defined, but other roots of trust are sure to follow.  For this reason,
>>>> I agree naming the new keyring "mok" should be avoided.
>>> As I said previously, I’m open to renaming, I just would like to have an
>>> agreement on the new name before changing everything.  The current proposed
>>> names I have heard are “.machine" and ".system-ca".  Is there a preference
>>> the maintainers feel is appropriate?  If so, please let me know and I’ll
>>> rename it. Thanks.
>>>
>> 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.

Thanks & Regards,

        - Nayna