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From:   Kees Cook <keescook@chromium.org>
Date:   Tue, 5 Jun 2018 15:26:32 -0700
Message-ID: <CAGXu5j+9P9HLvwC4WfHoxXsz7vYA_raStVDPzA=tNR9f9vr9=Q@mail.gmail.com>
Subject: Re: [PATCH v4a 8/8] module: replace the existing LSM hook in init_module
To:     Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc:     Paul Moore <paul@paul-moore.com>,
        linux-integrity <linux-integrity@vger.kernel.org>,
        linux-security-module <linux-security-module@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        David Howells <dhowells@redhat.com>,
        "Luis R . Rodriguez" <mcgrof@kernel.org>,
        Eric Biederman <ebiederm@xmission.com>,
        Kexec Mailing List <kexec@lists.infradead.org>,
        Andres Rodriguez <andresx7@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Jeff Vander Stoep <jeffv@google.com>,
        Casey Schaufler <casey@schaufler-ca.com>,
        James Morris <jmorris@namei.org>
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On Tue, Jun 5, 2018 at 2:35 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> On Tue, 2018-06-05 at 12:45 -0700, Kees Cook wrote:
>
>> And if you must have a separate enum, please change this to fail
>> closed instead of open (and mark the fall-through):
>>
>> int rc = -EPERM;
>>
>> switch (id) {
>> case LOADING_MODULE:
>>     rc = loadpin_read_file(NULL, READING_MODULE);
>>     /* Fall-through */
>> default:
>>     break;
>> }
>
> This will fail the sysfs firmware fallback loading and the kexec_load
> syscall without any message, as you have for init_module.  Is that
> what you want?

I'd prefer there be a full mapping of the enums so that everything
gets passed into loadpin_read_file() :)

Can the enum be shared or is that nonsensical?

-Kees

-- 
Kees Cook
Pixel Security