linux-kernel - Re: [PATCH] selinux: refactor mls_context_to

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Date:   Wed, 5 Sep 2018 18:16:46 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     jannh@...gle.com
Cc:     Stephen Smalley <sds@...ho.nsa.gov>,
        Eric Paris <eparis@...isplace.org>, selinux@...ho.nsa.gov,
        James Morris <jmorris@...ei.org>,
        Serge Hallyn <serge@...lyn.com>,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selinux: refactor mls_context_to_sid() and make it stricter

On Fri, Aug 31, 2018 at 11:47 AM Jann Horn <jannh@...gle.com> wrote:
> On Thu, Aug 9, 2018 at 3:56 AM Paul Moore <paul@...l-moore.com> wrote:
> > On Mon, Aug 6, 2018 at 5:19 PM Jann Horn <jannh@...gle.com> wrote:

...

> > In the case where we have a MLS policy loaded (pol->mls_enabled != 0)
> > and scontext is empty (scontext[0] = '\0'), we could end up returning
> > 0 couldn't we?  It seems like we might want a quick check for this
> > before we parse the low/high portions of the field into the rangep
> > array.
>
> I don't think so. In the first loop iteration, `sensitivity` will be
> an empty string, and so the hashtab_search() should return NULL,
> leading to -EINVAL. Am I missing something?

Looking at this again, no, I think you've got it right.  My guess is
that I just mistook the NULL sensitivity check at the top of the loop
as getting triggered in this case, which isn't the case here.  Sorry
for the noise.

> > As an aside, I believe my other comments on this patch still stand.
> > It's a nice improvement but I think there are some other small things
> > that need to be addressed.
>
> Is there anything I need to fix apart from the overly verbose comment
> and the unnecessary curly braces?

Nope.  I wouldn't even bother with that brace/comment changes, those
were minor nits and only worth changing if you needed to respin the
patch for some other reason.

Consider the patch merged, thanks!

--
paul moore
www.paul-moore.com