Re: [PATCH v1 08/12] IB/cma: Add net_dev and private data checks to RDMA CM

On 13/07/2015 21:14, Jason Gunthorpe wrote:

On Mon, Jun 22, 2015 at 03:42:37PM +0300, Haggai Eran wrote:

quoted

+	switch (ib_event->event) {
+	case IB_CM_REQ_RECEIVED:
+		req->device	= req_param->listen_id->device;
+		req->port	= req_param->port;
+		req->local_gid	= &req_param->primary_path->sgid;
+		req->service_id	= req_param->primary_path->service_id;
+		req->pkey	= be16_to_cpu(req_param->primary_path->pkey);

I feel pretty strongly that we should be using the pkey from the work
completion, not the pkey in the message.

The reason, if someone is using pkey like vlan, and expecting a
container to never receive packets outside the assigned pkey, then we
need to check each and every packet for the correct pkey before
associating it with that container.

The way I see it is that you have one RDMA CM agent in the system, and
the header parameters address it. This agent allows addressing several
namespaces, and they are de-muxed according to the parameters in the
payload.

So a container never receives a packet outside of its assigned pkeys,
but the pkey you look at (as well as the GID, and possibly the IP
address) all come from the payload.

When doing the namespace patches you should probably also look at
other CM GMPs than just the REQ and how the paths are setup and
consider what to do with the pkey. I'd probably suggest that the pkey
should be forced throughout the entire process to ensure it always
matches the ip device - at least for containers that is the right
thing.. I probably wouldn't turn it on for the root namespace though..

Once a connection has been established, following GMPs use a unique ID
to address this connection, so no more de-muxing is needed. What is
really missing here I guess is a mechanism that would enforce containers
to only use certain pkeys - perhaps with something like an RDMA cgroup.
It could force containers to only use approved pkeys not only with RDMA
CM, but through uverbs, and other user-space interfaces.

Haggai
--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html