linux-kernel - Re: [PATCH v9 2/8] integrity: Introduce a Linux keyring called machine

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Message-ID: <F1F41DB2-171A-4A6F-9AE7-E03C4D3B7DD0@oracle.com>
Date:   Tue, 11 Jan 2022 21:26:44 +0000
From:   Eric Snowberg <eric.snowberg@...cle.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>
CC:     David Howells <dhowells@...hat.com>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "ardb@...nel.org" <ardb@...nel.org>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        "jmorris@...ei.org" <jmorris@...ei.org>,
        "serge@...lyn.com" <serge@...lyn.com>,
        "nayna@...ux.ibm.com" <nayna@...ux.ibm.com>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
        "weiyongjun1@...wei.com" <weiyongjun1@...wei.com>,
        "keyrings@...r.kernel.org" <keyrings@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "James.Bottomley@...senpartnership.com" 
        <James.Bottomley@...senPartnership.com>,
        "pjones@...hat.com" <pjones@...hat.com>,
        Konrad Wilk <konrad.wilk@...cle.com>
Subject: Re: [PATCH v9 2/8] integrity: Introduce a Linux keyring called
 machine



> On Jan 11, 2022, at 11:16 AM, Mimi Zohar <zohar@...ux.ibm.com> wrote:
> 
> On Mon, 2022-01-10 at 23:25 +0000, Eric Snowberg wrote:
>>> Jarkko, my concern is that once this version of the patch set is
>>> upstreamed, would limiting which keys may be loaded onto the .machine
>>> keyring be considered a regression?
>> 
>> 
>> Currently certificates built into the kernel do not have a CA restriction on them.  
>> IMA will trust anything in this keyring even if the CA bit is not set.  While it would 
>> be advisable for a kernel to be built with a CA, nothing currently enforces it. 
>> 
>> My thinking for the dropped CA restriction patches was to introduce a new Kconfig.  
>> This Kconfig would do the CA enforcement on the machine keyring.  However if the 
>> Kconfig option was not set for enforcement, it would work as it does in this series, 
>> plus it would allow IMA to work with non-CA keys.  This would be done by removing 
>> the restriction placed in this patch. Let me know your thoughts on whether this would 
>> be an appropriate solution.  I believe this would get around what you are identifying as 
>> a possible regression.
> 
> True the problem currently exists with the builtin keys, but there's a
> major difference between trusting the builtin keys and those being
> loading via MOK.  This is an integrity gap that needs to be closed and
> shouldn't be expanded to keys on the .machine keyring.
> 
> "plus it would allow IMA to work with non-CA keys" is unacceptable.

Ok, I’ll leave that part out.  Could you clarify the wording I should include in the future 
cover letter, which adds IMA support, on why it is unacceptable for the end-user to
make this decision?