Re: [PATCH V3 1/5] RDMA/core: Transport-independent access flags

Doug Ledford
2015-07-10T22:33:41Z

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On 07/10/2015 03:54 PM, Jason Gunthorpe wrote:
> On Fri, Jul 10, 2015 at 02:42:45PM -0400, Tom Talpey wrote:
>
>>>> For the proposed iSER patch the problem is very acute, iser makes a
>>>> single PD and phys MR at boot time for each device. This means there
>>>> is a single machine wide unchanging rkey that allows remote physical
>>>> memory access. An attacker only has to repeatedly open QPs to iSER and
>>>> guess rkey values until they find it. Add in likely non-crypto
>>>> randomness for rkeys, and I bet it isn't even that hard to do.
>>
>> The rkeys have a PD, wich cannot be forged, so it's not a matter of
>> attacking, but it is most definitely a system integrity risk, as I
>> mentioned earlier, a simple arithmetic offset mistake can overwrite
>> anything.
>
> Can you explain this conclusion?

I think Tom's comment was referring to the fact that if you have a
trusted client, then a third party attacker can't attack your rkey
because they wouldn't have a QP in your PD and so the rkey would be
invalid for them. Your arguments have been centered around a malicious
client, his presumed a trusted client and malicious third party.

--
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
GPG KeyID: 0E572FDD

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