netdev - Re: net/smc and the RDMA core

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Message-ID: <20170504153155.GB854@obsidianresearch.com>
Date:   Thu, 4 May 2017 09:31:55 -0600
From:   Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:     Ursula Braun <ubraun@...ux.vnet.ibm.com>
Cc:     "hch@....de" <hch@....de>, Sagi Grimberg <sagi@...mberg.me>,
        Bart Van Assche <Bart.VanAssche@...disk.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>
Subject: Re: net/smc and the RDMA core

On Thu, May 04, 2017 at 03:08:39PM +0200, Ursula Braun wrote:
> 
> 
> On 05/04/2017 10:48 AM, hch@....de wrote:
> > 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 ??s 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.
> > 
> Thanks for pointing out these problems. We will address them.

So, you've created a huge security hole in the kernel, anyone who
loads your smc module is vunerable.

What are you going to do *RIGHT NOW* to mitigate this?

Jason