linux-kernel - Re: [PATCH] apparmor: Restore Y/N in /sys for apparmor's "enabled"

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Date:   Tue, 9 Apr 2019 08:16:35 -0700
From:   Kees Cook <keescook@...omium.org>
To:     David Rheinsberg <david.rheinsberg@...il.com>
Cc:     James Morris <jmorris@...ei.org>,
        John Johansen <john.johansen@...onical.com>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        linux-security-module <linux-security-module@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] apparmor: Restore Y/N in /sys for apparmor's "enabled"

On Mon, Apr 8, 2019 at 11:21 PM David Rheinsberg
<david.rheinsberg@...il.com> wrote:
>
> Hi
>
> On Mon, Apr 8, 2019 at 6:07 PM Kees Cook <keescook@...omium.org> wrote:
> >
> > Before commit c5459b829b71 ("LSM: Plumb visibility into optional "enabled"
> > state"), /sys/module/apparmor/parameters/enabled would show "Y" or "N"
> > since it was using the "bool" handler. After being changed to "int",
> > this switched to "1" or "0", breaking the userspace AppArmor detection
> > of dbus-broker. This restores the Y/N output while keeping the LSM
> > infrastructure happy.
> >
> > Before:
> >         $ cat /sys/module/apparmor/parameters/enabled
> >         1
> >
> > After:
> >         $ cat /sys/module/apparmor/parameters/enabled
> >         Y
> >
> > Reported-by: David Rheinsberg <david.rheinsberg@...il.com>
> > Link: https://lkml.kernel.org/r/CADyDSO6k8vYb1eryT4g6+EHrLCvb68GAbHVWuULkYjcZcYNhhw@mail.gmail.com
> > Fixes: c5459b829b71 ("LSM: Plumb visibility into optional "enabled" state")
> > Signed-off-by: Kees Cook <keescook@...omium.org>
> > ---
> > This fix, if John is okay with it, is needed in v5.1 to correct the
> > userspace regression reported by David.
> > ---
> >  security/apparmor/lsm.c | 49 ++++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 48 insertions(+), 1 deletion(-)
>
> This looks good to me. Thanks a lot! If this makes v5.1, I will leave
> the apparmor-detection in dbus-broker as it is, unless someone asks me
> to parse 0/1 as well?
>
> I cannot judge whether the apparmor_initialized check is correct, but
> for the parameter parsing:
>
> Reviewed-by: David Rheinsberg <david.rheinsberg@...il.com>

Thanks!

James, are you able to take this for v5.1 fixes?

-- 
Kees Cook