From: Trond Myklebust <trondmy@hammerspace.com>
To: "bfields@fieldses.org" <bfields@fieldses.org>,
"vvs@virtuozzo.com" <vvs@virtuozzo.com>
Cc: "anna.schumaker@netapp.com" <anna.schumaker@netapp.com>,
"khorenko@virtuozzo.com" <khorenko@virtuozzo.com>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
"eshatokhin@virtuozzo.com" <eshatokhin@virtuozzo.com>,
"chuck.lever@oracle.com" <chuck.lever@oracle.com>,
"jlayton@kernel.org" <jlayton@kernel.org>
Subject: Re: [PATCH 1/4] nfs: use-after-free in svc_process_common()
Date: Mon, 24 Dec 2018 08:21:04 +0000 [thread overview]
Message-ID: <6051cc19f72f9104806f628666ce54b31a5b184a.camel@hammerspace.com> (raw)
In-Reply-To: <83f3d959-1193-7222-f190-aee1de7eef0c@virtuozzo.com>
On Mon, 2018-12-24 at 09:05 +0300, Vasily Averin wrote:
> 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.
I'm not against the idea of using a function pointer, but I'm saying
that the transport is not unique per-netns. Instead, the transport is
usually per NFS mount, but you can always retrieve a pointer to it
directly in bc_svc_process() from req->rq_xprt.
> 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().
The function or flag used by bc_svc_common() could be added to req-
>rq_xprt->ops as another 'bc_' field and then passed to
svc_process_common() as the parameter.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com
next prev parent reply other threads:[~2018-12-24 8:21 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-17 16:23 [PATCH 1/4] nfs: use-after-free in svc_process_common() Vasily Averin
2018-12-17 17:49 ` Jeff Layton
2018-12-17 21:50 ` J. Bruce Fields
2018-12-18 6:45 ` Vasily Averin
2018-12-18 12:49 ` Trond Myklebust
2018-12-18 14:35 ` Vasily Averin
2018-12-18 14:55 ` Trond Myklebust
2018-12-18 20:02 ` Vasily Averin
2018-12-18 20:43 ` Trond Myklebust
2018-12-19 11:25 ` Vasily Averin
2018-12-20 1:39 ` Vasily Averin
2018-12-20 1:58 ` Trond Myklebust
2018-12-20 9:30 ` Vasily Averin
2018-12-20 11:58 ` Trond Myklebust
2018-12-21 1:00 ` bfields
2018-12-21 11:30 ` Vasily Averin
2018-12-21 17:39 ` Vasily Averin
2018-12-22 17:46 ` Vasily Averin
2018-12-23 20:52 ` bfields
2018-12-23 21:03 ` Vasily Averin
2018-12-23 23:56 ` Trond Myklebust
2018-12-24 5:51 ` Vasily Averin
2018-12-24 6:05 ` Vasily Averin
2018-12-24 8:21 ` Trond Myklebust [this message]
2018-12-24 8:59 ` Vasily Averin
2018-12-24 9:53 ` Trond Myklebust
2018-12-24 11:48 ` Vasily Averin
2018-12-18 21:31 ` Vladis Dronov
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