[lkml]   [2017]   [Nov]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v10 00/15] Introduce support for Dell SMBIOS over WMI
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.
> 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.
> 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.
> 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.
(cesky, pictures)
[unhandled content-type:application/pgp-signature]
 \ /
  Last update: 2017-11-09 10:52    [W:0.118 / U:4.892 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site