Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 06C89C43387 for ; Mon, 24 Dec 2018 06:05:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC22321773 for ; Mon, 24 Dec 2018 06:05:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725896AbeLXGFX (ORCPT ); Mon, 24 Dec 2018 01:05:23 -0500 Received: from relay.sw.ru ([185.231.240.75]:38306 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725849AbeLXGFX (ORCPT ); Mon, 24 Dec 2018 01:05:23 -0500 Received: from [172.16.24.21] by relay.sw.ru with esmtp (Exim 4.91) (envelope-from ) id 1gbJMZ-0001zK-WF; Mon, 24 Dec 2018 09:05:16 +0300 Subject: Re: [PATCH 1/4] nfs: use-after-free in svc_process_common() To: Trond Myklebust , "bfields@fieldses.org" Cc: "anna.schumaker@netapp.com" , "khorenko@virtuozzo.com" , "linux-nfs@vger.kernel.org" , "eshatokhin@virtuozzo.com" , "chuck.lever@oracle.com" , "jlayton@kernel.org" References: <134cf19c-e698-abed-02de-1659f9a5d4fb@virtuozzo.com> <20181217215026.GA8564@fieldses.org> <67f477b704d34b369f0530891a219f383f964001.camel@hammerspace.com> <4d878140-02c0-e306-fee6-1573d9fdecf2@virtuozzo.com> <068f1741afc54367853a2e4501fd95c2ab12a989.camel@hammerspace.com> <20181221010007.GA10196@fieldses.org> <9082b04a-8235-4b9d-39ae-1462fe350935@virtuozzo.com> From: Vasily Averin Message-ID: <83f3d959-1193-7222-f190-aee1de7eef0c@virtuozzo.com> Date: Mon, 24 Dec 2018 09:05:14 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On 12/24/18 8:51 AM, Vasily Averin wrote: > On 12/24/18 2:56 AM, Trond Myklebust wrote: >> On Sat, 2018-12-22 at 20:46 +0300, Vasily Averin wrote: >>> On 12/21/18 4:00 AM, bfields@fieldses.org wrote: >>>> On Tue, Dec 18, 2018 at 02:55:15PM +0000, Trond Myklebust wrote: >>>>> No. We don't care about xpt_flags for the back channel because >>>>> there is >>>>> no "server transport". The actual transport is stored in the >>>>> 'struct >>>>> rpc_rqst', and is the struct rpc_xprt corresponding to the client >>>>> socket or RDMA channel. >>>>> >>>>> IOW: All we really need in svc_process_common() is to be able to >>>>> run >>>>> rqstp->rq_xprt->xpt_ops->xpo_prep_reply_hdr(), and that can be >>>>> passed >>>>> either as a pointer to the struct svc_xprt_ops itself. >>>> >>>> For what it's worth, I'd rather get rid of that op--it's an awfully >>>> roundabout way just to do "svc_putnl(resv, 0);" in the tcp case. >>> >>> Do you mean that svc_create_xprt(serv, "tcp-bc", ...) was used ONLY >>> to call >>> svc_tcp_prep_reply_hdr() in svc_process_common() ? >>> And according call for rdma-bc does nothing useful at all? >>> >>> I've just tried to remove svc_create_xprt() from xs_tcp_bc_up() and >>> just >>> provide pointer to svc_tcp_prep_reply_hdr() in svc_process_common() >>> via per-netns sunrpc_net -- and seems it was enough, my testcase >>> worked correctly. >> >> I don't see how that function is related to net namespaces. As far as I >> can tell, it only signals whether or not the type of transport uses the >> TCP record marking scheme. > > We need to know which kind of transport is used in specified net namespace, > for example init_ns can use RDMA transport and netns "second" can use > TCP transport at the same time. > If you do not like an idea to use function pointer as a mark -- ok > I can save only some boolean flag on sunrpc_net, check it in svc_process_common() > and if it is set -- call svc_tcp_prep_reply_hdr() directly. moreover, I can do not change sunrpc_net at all, I can check in bc_svc_common() which transport uses incoming svc_req and provide such flag as new parameter to svc_process_common(). >> IOW: it depends on whether the client is using a stream based protocol >> like TCP, or a datagram-like protocol like UDP, or RDMA. Whether that >> use is occurring in a private net namespace or in the init process >> namespace would be irrelevant. >> >>> Am I missed something probably? >>> Should we really remove svc_create_xprt( "tcp/rdma-bc"...) related >>> stuff? ? >> >> Agreed. The 'bc_up' callback in struct rpc_xprt_ops serves no >> discernible purpose, and can be removed. >>