linux-kernel - Re: [RFC PATCH v2] fw_lockdown: new micro LSM module to prevent loading unsigned firmware

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Date:   Tue, 14 Nov 2017 00:55:46 +0100
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     "Luis R. Rodriguez" <mcgrof@...nel.org>
Cc:     Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        David Howells <dhowells@...hat.com>,
        linux-integrity <linux-integrity@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Andy Lutomirski <luto@...nel.org>,
        James Bottomley <James.Bottomley@...senpartnership.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Kyle McMartin <kyle@...nel.org>,
        Ben Hutchings <ben@...adent.org.uk>,
        Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        "AKASHI, Takahiro" <takahiro.akashi@...aro.org>
Subject: Re: [RFC PATCH v2] fw_lockdown: new micro LSM module to prevent
 loading unsigned firmware

On Mon, Nov 13, 2017 at 08:51:54PM +0100, Luis R. Rodriguez wrote:
> On Mon, Nov 13, 2017 at 02:36:47PM -0500, Mimi Zohar wrote:
> > On Mon, 2017-11-13 at 20:05 +0100, Luis R. Rodriguez wrote:
> > > > + * fw_lockdown_read_file - prevent loading of unsigned firmware
> > > > + * @file: pointer to firmware
> > > > + * @read_id: caller identifier
> > > > + *
> > > > + * Prevent loading of unsigned firmware in lockdown mode.
> > > > + */
> > > > +static int fw_lockdown_read_file(struct file *file, enum kernel_read_file_id id)
> > > > +{
> > > > +	if (id == READING_FIRMWARE) {
> > > > +		if (!is_ima_appraise_enabled() &&
> > > > +		    kernel_is_locked_down("Loading of unsigned firmware"))
> > > > +			return -EACCES;
> > > > +	}

We also have READING_FIRMWARE_PREALLOC_BUFFER now. So the above
is missing a check for that as well.

  Luis