Re: net/smc and the RDMA core

On Thu, May 04, 2017 at 11:43:50AM +0300, Sagi Grimberg wrote:

I would also suggest that you stop exposing the DMA MR for remote
access (at least by default) and use a proper reg_mr operations with a
limited lifetime on a properly sized buffer.

Yes, exposing the default DMA MR is a _major_ security risk.  As soon
as SMC is enabled this will mean a remote system has full read/write
access to the local systems memory.

There іs a reason why I removed the ib_get_dma_mr function and replaced
it with the IB_PD_UNSAFE_GLOBAL_RKEY key that has _UNSAFE_ in the name
and a very long comment explaining why, and I'm really disappointed that
we got a driver merged that instead of asking on the relevant list on
why a change unexpertong a function it needed happened and instead
tried the hard way to keep a security vulnerarbility alive.
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