On Tue, Feb 2, 2021 at 3:51 PM Ben Widawsky <ben.widawsky(a)intel.com> wrote:
On 21-02-01 13:28:48, Konrad Rzeszutek Wilk wrote:
> On Fri, Jan 29, 2021 at 04:24:37PM -0800, Ben Widawsky wrote:
> > The Get Log command returns the actual log entries that are advertised
> > via the Get Supported Logs command (0400h). CXL device logs are selected
> > by UUID which is part of the CXL spec. Because the driver tries to
> > sanitize what is sent to hardware, there becomes a need to restrict the
> > types of logs which can be accessed by userspace. For example, the
> > vendor specific log might only be consumable by proprietary, or offline
> > applications, and therefore a good candidate for userspace.
> > The current driver infrastructure does allow basic validation for all
> > commands, but doesn't inspect any of the payload data. Along with Get
> > Log support comes new infrastructure to add a hook for payload
> > validation. This infrastructure is used to filter out the CEL UUID,
> > which the userspace driver doesn't have business knowing, and taints on
> > invalid UUIDs being sent to hardware.
> Perhaps a better option is to reject invalid UUIDs?
> And if you really really want to use invalid UUIDs then:
> 1) Make that code wrapped in CONFIG_CXL_DEBUG_THIS_IS_GOING_TO..?
> 2) Wrap it with lockdown code so that you can't do this at all
> when in LOCKDOWN_INTEGRITY or such?
The commit message needs update btw as CEL is allowed in the latest rev of the
We could potentially combine this with the now added (in a branch) CONFIG_RAW
config option. Indeed I think that makes sense. Dan, thoughts?
Yeah, unknown UUIDs blocking is the same risk as raw commands as a
vendor can trigger any behavior they want. A "CONFIG_RAW depends on
!CONFIG_INTEGRITY" policy sounds reasonable as well.