From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH v10 00/15] Introduce support for Dell SMBIOS over WMI Date: Thu, 9 Nov 2017 10:52:08 +0100 Message-ID: <20171109095208.GD6074@amd> References: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="kvUQC+jR9YzypDnK" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Mario Limonciello Cc: dvhart@infradead.org, Andy Shevchenko , LKML , platform-driver-x86@vger.kernel.org, Andy Lutomirski , quasisec@google.com, pali.rohar@gmail.com, rjw@rjwysocki.net, mjg59@google.com, hch@lst.de, Greg KH , Alan Cox List-Id: platform-driver-x86.vger.kernel.org --kvUQC+jR9YzypDnK Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu 2017-10-19 12:50:03, Mario Limonciello wrote: > The existing way that the dell-smbios helper module and associated > other drivers (dell-laptop, dell-wmi) communicate with the platform > really isn't secure. It requires creating a buffer in physical > DMA32 memory space and passing that to the platform via SMM. >=20 > Since the platform got a physical memory pointer, you've just got > to trust that the platform has only modified (and accessed) memory > within that buffer. >=20 > Dell Platform designers recognize this security risk and offer a > safer way to communicate with the platform over ACPI. This is > in turn exposed via a WMI interface to the OS. >=20 > When communicating over WMI-ACPI the communication doesn't occur > with physical memory pointers. When the ASL is invoked, the fixed > length ACPI buffer is copied to a small operating region. The ASL > will invoke the SMI, and SMM will only have access to this operating > region. When the ASL returns the buffer is copied back for the OS > to process. SMM has access anywhere it wants. This may be good idea, but definitely not for "security" reasons. Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --kvUQC+jR9YzypDnK Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAloEJUgACgkQMOfwapXb+vJ1HQCeL7vFIxFVpJhHSBXqrEho/OXx 954Anj5OE5Uzvccu2jxIqC3GzlucU14l =e0gt -----END PGP SIGNATURE----- --kvUQC+jR9YzypDnK--