On Wed, Nov 01, 2017 at 02:25:21PM -0500, 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. > > This method of communication should also deprecate the usage of the > dcdbas kernel module and software dependent upon it's interface. > Instead offer a character device interface for communicating with this > ASL method to allow userspace to use instead. > > To faciliate that this patch series introduces a generic way for WMI > drivers to be able to create discoverable character devices with > a predictable IOCTL interface through the WMI bus when desired. > Requiring WMI drivers to explicitly ask for this functionality will > act as an effective vendor whitelist to character device creation. > > Some of this work is the basis for what will be a proper interpreter > of MOF in the kernel and controls for what drivers will be able to > do with that MOF. > > NOTE: This patch series is intended to go on top of platform-drivers-x86 > linux-next. > > For convenience the entire series including those is also available here: > https://github.com/dell/linux/tree/wmi-smbios Queued for testing, thanks Mario. -- Darren Hart VMware Open Source Technology Center
