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From: Eric Blake <eblake@redhat.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: "yukuai (C)" <yukuai3@huawei.com>,
	josef@toxicpanda.com, axboe@kernel.dk, hch@infradead.org,
	linux-block@vger.kernel.org, nbd@other.debian.org,
	linux-kernel@vger.kernel.org, yi.zhang@huawei.com
Subject: Re: [patch v8 3/7] nbd: check sock index in nbd_read_stat()
Date: Wed, 22 Sep 2021 07:12:01 -0500	[thread overview]
Message-ID: <20210922121201.neskyaenjh64wmyb@redhat.com> (raw)
In-Reply-To: <YUr1v8zylPOFFXTO@T590>

On Wed, Sep 22, 2021 at 05:22:07PM +0800, Ming Lei wrote:
> 
> I think this one relies on nbd protocol between server and client, and
> does the protocol require both request and reply xmitted via same
> socket?

Yes, a reply must be transmitted on the same socket as the request
came over.  This is because independent sockets are not required to
use distinct 64-bit handles, and there is no way for a server to tell
if independent clients are related to one another; sending a reply on
the wrong socket is thus not guaranteed to reach the intended client.
Thus, a compliant server will never send a reply over a different
socket than the original request, and if a client ever gets a reply
with a handle it was not expecting, then the server is buggy or
malicious.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


  reply	other threads:[~2021-09-22 12:12 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-16  9:33 [patch v8 0/7] handle unexpected message from server Yu Kuai
2021-09-16  9:33 ` [patch v8 1/7] nbd: don't handle response without a corresponding request message Yu Kuai
2021-09-16  9:33 ` [patch v8 2/7] nbd: make sure request completion won't concurrent Yu Kuai
2021-09-16  9:33 ` [patch v8 3/7] nbd: check sock index in nbd_read_stat() Yu Kuai
2021-09-19 10:34   ` yukuai (C)
2021-09-22  9:22     ` Ming Lei
2021-09-22 12:12       ` Eric Blake [this message]
2021-09-22 12:21       ` yukuai (C)
2021-09-22 15:56       ` Wouter Verhelst
2021-09-23  0:29   ` Ming Lei
2021-09-16  9:33 ` [patch v8 4/7] nbd: don't start request if nbd_queue_rq() failed Yu Kuai
2021-09-16 12:48   ` Ming Lei
2021-09-16  9:33 ` [patch v8 5/7] nbd: clean up return value checking of sock_xmit() Yu Kuai
2021-09-16 12:49   ` Ming Lei
2021-09-16  9:33 ` [patch v8 6/7] nbd: partition nbd_read_stat() into nbd_read_reply() and nbd_handle_reply() Yu Kuai
2021-09-16 12:53   ` Ming Lei
2021-09-16  9:33 ` [patch v8 7/7] nbd: fix uaf in nbd_handle_reply() Yu Kuai
2021-09-16 12:58   ` Ming Lei
2021-09-16 13:10     ` yukuai (C)
2021-09-16 13:55       ` Ming Lei
2021-09-16 14:05         ` yukuai (C)
2021-09-16 14:18   ` [PATCH v9] " Yu Kuai
2021-09-17  3:33     ` Ming Lei
2021-10-17 13:09     ` Jens Axboe
2021-09-23 13:33 ` [patch v8 0/7] handle unexpected message from server yukuai (C)
2021-09-29 12:54   ` yukuai (C)
2021-10-08  7:17     ` yukuai (C)
2021-10-15  8:19       ` yukuai (C)
2021-10-15 16:08 ` Josef Bacik
2021-10-17 13:09 ` Jens Axboe

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