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Message-Id: <20121214.131602.930994526954658624.davem@davemloft.net>
Date: Fri, 14 Dec 2012 13:16:02 -0500 (EST)
From: David Miller <davem@...emloft.net>
To: jasowang@...hat.com
Cc: mst@...hat.com, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, pmoore@...hat.com,
mprivozn@...hat.com, wkevils@...il.com
Subject: Re: [PATCH] tuntap: fix ambigious multiqueue API
From: Jason Wang <jasowang@...hat.com>
Date: Fri, 14 Dec 2012 17:53:30 +0800
> The current multiqueue API is ambigious which may confuse both user and LSM to
> do things correctly:
>
> - Both TUNSETIFF and TUNSETQUEUE could be used to create the queues of a tuntap
> device.
> - TUNSETQUEUE were used to disable and enable a specific queue of the
> device. But since the state of tuntap were completely removed from the queue,
> it could be used to attach to another device (there's no such kind of
> requirement currently, and it needs new kind of LSM policy.
> - TUNSETQUEUE could be used to attach to a persistent device without any
> queues. This kind of attching bypass the necessary checking during TUNSETIFF
> and may lead unexpected result.
>
> So this patch tries to make a cleaner and simpler API by:
>
> - Only allow TUNSETIFF to create queues.
> - TUNSETQUEUE could be only used to disable and enabled the queues of a device,
> and the state of the tuntap device were not detachd from the queues when it
> was disabled, so TUNSETQUEUE could be only used after TUNSETIFF and with the
> same device.
>
> This is done by introducing a list which keeps track of all queues which were
> disabled. The queue would be moved between this list and tfiles[] array when it
> was enabled/disabled. A pointer of the tun_struct were also introdued to track
> the device it belongs to when it was disabled.
>
> After the change, the isolation between management and application could be done
> through: TUNSETIFF were only called by management software and TUNSETQUEUE were
> only called by application.For LSM/SELinux, the things left is to do proper
> check during tun_set_queue() if needed.
>
> Signed-off-by: Jason Wang <jasowang@...hat.com>
Applied.
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