linux-kernel - Re: [PATCH v2] integrity: Always reference the blacklist keyring with apprasial

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Date:   Wed, 12 Jul 2023 17:33:55 -0400
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Eric Snowberg <eric.snowberg@...cle.com>
Cc:     "dmitry.kasatkin@...il.com" <dmitry.kasatkin@...il.com>,
        "paul@...l-moore.com" <paul@...l-moore.com>,
        "jmorris@...ei.org" <jmorris@...ei.org>,
        "serge@...lyn.com" <serge@...lyn.com>,
        Roberto Sassu <roberto.sassu@...wei.com>,
        Kanth Ghatraju <kanth.ghatraju@...cle.com>,
        Konrad Wilk <konrad.wilk@...cle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-integrity@...r.kernel.org" <linux-integrity@...r.kernel.org>,
        "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH v2] integrity: Always reference the blacklist keyring
 with apprasial

On Wed, 2023-07-12 at 21:12 +0000, Eric Snowberg wrote:
> 
> > On Jul 12, 2023, at 11:40 AM, Mimi Zohar <zohar@...ux.ibm.com> wrote:
> > 
> > On Wed, 2023-07-05 at 18:52 -0400, Eric Snowberg wrote:
> >> Commit 273df864cf746 ("ima: Check against blacklisted hashes for files with
> >> modsig") introduced an appraise_flag option for referencing the blacklist
> >> keyring.  Any matching binary found on this keyring fails signature
> >> validation. This flag only works with module appended signatures.
> >> 
> >> An important part of a PKI infrastructure is to have the ability to do
> >> revocation at a later time should a vulnerability be found.  Expand the
> >> revocation flag usage to all appraisal functions. The flag is now
> >> enabled by default. Setting the flag with an IMA policy has been
> >> deprecated. Without a revocation capability like this in place, only
> >> authenticity can be maintained. With this change, integrity can now be
> >> achieved with digital signature based IMA appraisal.
> >> 
> >> Signed-off-by: Eric Snowberg <eric.snowberg@...cle.com>
> > 
> > Thanks, Eric.  Other than including "appraise_flag=check_blacklist"
> > when displaying the measurement list, it looks good.
> 
> Thanks for your review.  
> 
> I want to make sure I understand the request here.  Do you mean you 
> don’t want to see  “appraise_flag=check_blacklist”  when you cat 
> /sys/kernel/security/ima/policy?  Or are you referencing a change in the 
> /sys/kernel/security/ima/ascii_runtime_measurements list? Thanks.

The IMA policy rules as displayed via <securityfs>/ima/policy should
not contain  “appraise_flag=check_blacklist".

-- 
thanks,

Mimi