RE: [PATCH v4 1/3] Drivers: hv: vmbus: Add vmbus_requestor data structure for VMBus hardening

[Michael Kelley]

From: Andres Beltran <lkmlabelt@xxxxxxxxx> Sent: Tuesday, June 30, 2020 5:12 PM
> 
> Currently, VMbus drivers use pointers into guest memory as request IDs
> for interactions with Hyper-V. To be more robust in the face of errors
> or malicious behavior from a compromised Hyper-V, avoid exposing
> guest memory addresses to Hyper-V. Also avoid Hyper-V giving back a
> bad request ID that is then treated as the address of a guest data
> structure with no validation. Instead, encapsulate these memory
> addresses and provide small integers as request IDs.
> 
> Signed-off-by: Andres Beltran <lkmlabelt@xxxxxxxxx>
> ---
> Changes in v4:
> 	- Use channel->rqstor_size to check if rqstor has been
> 	  initialized.
> Changes in v3:
>         - Check that requestor has been initialized in
>           vmbus_next_request_id() and vmbus_request_addr().
> Changes in v2:
>         - Get rid of "rqstor" variable in __vmbus_open().
> 
>  drivers/hv/channel.c   | 158 +++++++++++++++++++++++++++++++++++++++++
>  include/linux/hyperv.h |  21 ++++++
>  2 files changed, 179 insertions(+)

Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>