RE: [PATCH v6 1/3] Drivers: hv: vmbus: Add vmbus_requestor data structure for VMBus hardening

[Michael Kelley]

From: Andres Beltran <lkmlabelt@xxxxxxxxx> Sent: Wednesday, July 22, 2020 3:39 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 v6:
> 	- Offset request IDs by 1 keeping the original initialization
> 	  code.
> Changes in v5:
>         - Add support for unsolicited messages sent by the host with a
>           request ID of 0.
> 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   | 170 +++++++++++++++++++++++++++++++++++++++++
>  include/linux/hyperv.h |  21 +++++
>  2 files changed, 191 insertions(+)

Tested-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>