Re: [PATCH 10/10] svcrdma: Documentation update for the FastReg memory model

["J. Bruce Fields" <bfields@fieldses.org>]

On Mon, Sep 29, 2008 at 10:07:25PM -0500, Tom Tucker wrote:
> J. Bruce Fields wrote:
>> On Thu, Sep 25, 2008 at 08:35:26AM -0500, Tom Tucker wrote:
>>> J. Bruce Fields wrote:
>>>> This explanation is helpful, thanks.  It would also be helpful if we
>>>> could boil down the advice to just a sentence or two for the busy admin.
>>>> Something like:  unless you have card XYZ and kernel 2.6.y, do *not* use
>>>> rdma on a network where you cannot trust every machine....
>>>
>>> Would it be better to say, "Do not use RDMA on a network where your   
>>> policy requires a security model stronger than tcp/auth_unix."
>>
>> I'm not worried about the case where the security provided is roughly
>> equivalent to that provided by tcp/auth_unix.
>>
>> I'm worried about the non-"Fast Reg" case where I thought you were
>> saying that the network could access memory other than that meant to
>> hold rpc data.
>>
>
> Ok, so maybe we could state the security exposure of ALLPHYSICAL instead  
> of dwelling on the relative differences between the similar exposures of  
> tcp/auth_unix vs. fastreg?

Right.  It's all interesting, so I wouldn't cut anything out--but you
could put off the details to the end; e.g., start with "in situation
<...>, nfs/rdma provides roughly the same security as nfs over tcp and
auth_unix (see below for more details)".

> I'd also like to get to fastreg as a default at some point.

OK, good.

> What's your perspective on the lifetime of bounce buffers, memory  
> windows, and the other strategies in client?

I'm ignorant.  Pointer to something else I should read?

I assume there are similar issues on the client?

--b.