Re: [PATCH net-next v2] net/rds: restrict the rdma_cm ids to IB devices

[sashiko-bot@kernel.org]

> RDS only has an IB transport, but it never tells the rdma_cm so.  The
> listener created in rds_rdma_listen_init() is therefore installed on
> every RDMA device in the system, including iWARP RNICs, and the id an
> outgoing connection resolves through in rds_ib_conn_path_connect()
> may be bound to whichever device the address resolution picks:
> rds_ib_laddr_check() only vouched for the local address being served
> by one of RDS's IB devices, while cma_acquire_dev_by_src_ip() walks
> every RDMA device for the same address, so a software iWARP device
> attached to the same netdev can win.  The event handler then runs
> the IB transport's callbacks against a device that is not one.
> 
> The rdma_cm has an API for exactly this since commit a760e80e90f5
> ("RDMA/core: introduce rdma_restrict_node_type()").  Restrict all
> three ids RDS creates - the listener, the per-connection id and the
> probe id in rds_ib_laddr_check_cm() - to RDMA_NODE_IB_CA before they
> are bound, so that the listener is only installed on IB devices, an
> outgoing connection can only bind one, and the address check's bind
> fails outright on anything else (its explicit node_type test now only
> guards against a device with no node type at all).
> 
> With that, the connect-request rejection for non-IB devices in the
> event handler becomes unreachable; it stays as the last line of
> defence and is what stable kernels without the new API rely on.
> 
> Assisted-by: Claude-Code:claude-fable-5
> Signed-off-by: Allison Henderson <achender@kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260919061042.250462-1-achender@kernel.org?part=1