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

[Jason Wang]

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