[RFC PATCH] virtio: document virtio hardening status and TODO

From: Jason Wang
Date: Fri Oct 14 2022 - 00:21:00 EST


This patch summarizes the status of hardening and TODO of hardening
virtio core and drivers.

Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
Documentation/security/virtio/core.rst | 49 ++++++++++++++++++++++++++
MAINTAINERS | 1 +
2 files changed, 50 insertions(+)
create mode 100644 Documentation/security/virtio/core.rst

diff --git a/Documentation/security/virtio/core.rst b/Documentation/security/virtio/core.rst
new file mode 100644
index 000000000000..b8baa104d7c8
--- /dev/null
+++ b/Documentation/security/virtio/core.rst
@@ -0,0 +1,49 @@
+================
+Virtio hardening
+================
+
+The virtio core and drivers should not trust the devices. This means
+all kinds of input from the device must be validated before being
+used. This document summarizes the current status and TODO for this
+validation/hardening efforts.
+
+
+Status
+======
+
+The virtio core and drivers has done some basic hardening:
+
+* Config callback hardening: The core makes sure the config interrupt
+ callbacks are enabled after the driver is ready and disable before
+ the driver is removed.
+
+* Descriptor ring hardening: The metadata of a descriptor were copied
+ and stored in a driver private memory that can not be accessed by the
+ device. The eliminates the device triggerable behaviours through the
+ descriptor ring.
+
+* Device configuration space validation: Some of the virtio drivers
+ validates the fields of device configuration space before try to use
+ them.
+
+
+TODO
+====
+
+* Input buffer length validation: The virtio core needs to validate
+ the input buffer length validation before passing them to individual
+ virtio drivers.
+
+* Virtqueue callback hardening: The virtio core (or with the help of
+ the drivers) should guarantee that the virtqueue callbacks should not
+ be triggered before the driver is ready or after the driver is
+ removed.
+
+* Transport specific data validation: The virtio transport driver should
+ validate the virtio transport specific data provided by the device
+ before trying to use them in the probing.
+
+* Device specific validation: Driver should validate the device specific
+ metadata before being used by a specific subsystem.
+
+
diff --git a/MAINTAINERS b/MAINTAINERS
index 673b9f9b8d8a..b33cc5c751c1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21516,6 +21516,7 @@ S: Maintained
F: Documentation/ABI/testing/sysfs-bus-vdpa
F: Documentation/ABI/testing/sysfs-class-vduse
F: Documentation/devicetree/bindings/virtio/
+F: Documentation/security/virtio/core.rst
F: drivers/block/virtio_blk.c
F: drivers/crypto/virtio/
F: drivers/net/virtio_net.c
--
2.25.1