From: "J. Bruce Fields" Subject: Re: [PATCH 10/10] svcrdma: Documentation update for the FastReg memory model Date: Tue, 30 Sep 2008 14:44:33 -0400 Message-ID: <20080930184433.GC12268@fieldses.org> References: <1221564879-85046-6-git-send-email-tom@opengridcomputing.com> <1221564879-85046-7-git-send-email-tom@opengridcomputing.com> <1221564879-85046-8-git-send-email-tom@opengridcomputing.com> <1221564879-85046-9-git-send-email-tom@opengridcomputing.com> <1221564879-85046-10-git-send-email-tom@opengridcomputing.com> <1221564879-85046-11-git-send-email-tom@opengridcomputing.com> <20080924212102.GD10841@fieldses.org> <48DB939E.4090503@opengridcomputing.com> <20080926234006.GA9889@fieldses.org> <48E197ED.6080409@opengridcomputing.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-nfs@vger.kernel.org, Tom Talpey To: Tom Tucker Return-path: Received: from mail.fieldses.org ([66.93.2.214]:60339 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753686AbYI3Sof (ORCPT ); Tue, 30 Sep 2008 14:44:35 -0400 In-Reply-To: <48E197ED.6080409@opengridcomputing.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: 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.