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From:   Steve Grubb <sgrubb@redhat.com>
To:     Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Cc:     Paul Moore <paul@paul-moore.com>, Mimi Zohar <zohar@linux.ibm.com>,
        rgb@redhat.com, linux-integrity@vger.kernel.org,
        linux-audit@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] integrity: Add errno field in audit message
Date:   Tue, 16 Jun 2020 11:55:42 -0400
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Organization: Red Hat
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On Tuesday, June 16, 2020 11:43:31 AM EDT Lakshmi Ramasubramanian wrote:
> On 6/16/20 8:29 AM, Steve Grubb wrote:
> >>>>> The idea is a good idea, but you're assuming that "result" is always
> >>>>> errno.  That was probably true originally, but isn't now.  For
> >>>>> example, ima_appraise_measurement() calls xattr_verify(), which
> >>>>> compares the security.ima hash with the calculated file hash.  On
> >>>>> failure, it returns the result of memcmp().  Each and every code path
> >>>>> will need to be checked.
> >>>> 
> >>>> Good catch Mimi.
> >>>> 
> >>>> Instead of "errno" should we just use "result" and log the value given
> >>>> in the result parameter?
> >>> 
> >>> That would likely collide with another field of the same name which is
> >>> the
> >>> operation's results. If it really is errno, the name is fine. It's
> >>> generic
> >>> enough that it can be reused on other events if that mattered.
> >> 
> >> Steve, what is the historical reason why we have both "res" and
> >> "result" for indicating a boolean success/fail?  I'm just curious how
> >> we ended up this way, and who may still be using "result".
> > 
> > I think its pam and some other user space things did this. But because of
> > mixed machines in datacenters supporting multiple versions of OS, we have
> > to leave result alone. It has to be 0,1 or success/fail. We cannot use
> > it for errno.
> 
> As Mimi had pointed out, since the value passed in result parameter is
> not always an error code, "errno" is not an appropriate name.
> 
> Can we add a new field, say, "op_result" to report the result of the
> specified operation?

Sure. But since it is errno sometimes, how would we know when to translate 
it?

-Steve