[3.8-rc] tuntap: refuse to re-attach to different tun_struct

Submitted by Stefan Hajnoczi on Jan. 10, 2013, 7:59 a.m.

Details

Message ID 1357804788-19976-1-git-send-email-stefanha@redhat.com
State Accepted
Delegated to: David Miller
Headers show

Commit Message

Stefan Hajnoczi Jan. 10, 2013, 7:59 a.m.
Multiqueue tun devices support detaching a tun_file from its tun_struct
and re-attaching at a later point in time.  This allows users to disable
a specific queue temporarily.

ioctl(TUNSETIFF) allows the user to specify the network interface to
attach by name.  This means the user can attempt to attach to interface
"B" after detaching from interface "A".

The driver is not designed to support this so check we are re-attaching
to the right tun_struct.  Failure to do so may lead to oops.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
This fix is for 3.8-rc.

 drivers/net/tun.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Jason Wang Jan. 10, 2013, 9:25 a.m.
On Thursday, January 10, 2013 08:59:48 AM Stefan Hajnoczi wrote:
> Multiqueue tun devices support detaching a tun_file from its tun_struct
> and re-attaching at a later point in time.  This allows users to disable
> a specific queue temporarily.
> 
> ioctl(TUNSETIFF) allows the user to specify the network interface to
> attach by name.  This means the user can attempt to attach to interface
> "B" after detaching from interface "A".
> 
> The driver is not designed to support this so check we are re-attaching
> to the right tun_struct.  Failure to do so may lead to oops.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> This fix is for 3.8-rc.
> 
>  drivers/net/tun.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index fbd106e..cf6da6e 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -491,6 +491,8 @@ static int tun_attach(struct tun_struct *tun, struct
> file *file) err = -EINVAL;
>  	if (rcu_dereference_protected(tfile->tun, lockdep_rtnl_is_held()))
>  		goto out;
> +	if (tfile->detached && tun != tfile->detached)
> +		goto out;
> 
>  	err = -EBUSY;
>  	if (!(tun->flags & TUN_TAP_MQ) && tun->numqueues == 1)

Thanks.

Acked-by: Jason Wang <jasowang@redhat.com>

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David Miller Jan. 10, 2013, 10:39 p.m.
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 10 Jan 2013 08:59:48 +0100

> Multiqueue tun devices support detaching a tun_file from its tun_struct
> and re-attaching at a later point in time.  This allows users to disable
> a specific queue temporarily.
> 
> ioctl(TUNSETIFF) allows the user to specify the network interface to
> attach by name.  This means the user can attempt to attach to interface
> "B" after detaching from interface "A".
> 
> The driver is not designed to support this so check we are re-attaching
> to the right tun_struct.  Failure to do so may lead to oops.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Applied.
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Jason Wang Jan. 11, 2013, 1:29 a.m.
On 01/11/2013 06:39 AM, David Miller wrote:
> From: Stefan Hajnoczi <stefanha@redhat.com>
> Date: Thu, 10 Jan 2013 08:59:48 +0100
>
>> Multiqueue tun devices support detaching a tun_file from its tun_struct
>> and re-attaching at a later point in time.  This allows users to disable
>> a specific queue temporarily.
>>
>> ioctl(TUNSETIFF) allows the user to specify the network interface to
>> attach by name.  This means the user can attempt to attach to interface
>> "B" after detaching from interface "A".
>>
>> The driver is not designed to support this so check we are re-attaching
>> to the right tun_struct.  Failure to do so may lead to oops.
>>
>> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> Applied.
Hi David:

Any chance that I can have a respin on this patch, there's still a bug
after this patch. Or I just can send a patch on top?

Thanks
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David Miller Jan. 11, 2013, 5:12 a.m.
From: Jason Wang <jasowang@redhat.com>
Date: Fri, 11 Jan 2013 09:29:20 +0800

> On 01/11/2013 06:39 AM, David Miller wrote:
>> From: Stefan Hajnoczi <stefanha@redhat.com>
>> Date: Thu, 10 Jan 2013 08:59:48 +0100
>>
>>> Multiqueue tun devices support detaching a tun_file from its tun_struct
>>> and re-attaching at a later point in time.  This allows users to disable
>>> a specific queue temporarily.
>>>
>>> ioctl(TUNSETIFF) allows the user to specify the network interface to
>>> attach by name.  This means the user can attempt to attach to interface
>>> "B" after detaching from interface "A".
>>>
>>> The driver is not designed to support this so check we are re-attaching
>>> to the right tun_struct.  Failure to do so may lead to oops.
>>>
>>> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
>> Applied.
> Hi David:
> 
> Any chance that I can have a respin on this patch, there's still a bug
> after this patch. Or I just can send a patch on top?

If I've applied it, there is no reverting.
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Jason Wang Jan. 11, 2013, 8:38 a.m.
On 01/11/2013 01:12 PM, David Miller wrote:
> From: Jason Wang <jasowang@redhat.com>
> Date: Fri, 11 Jan 2013 09:29:20 +0800
>
>> On 01/11/2013 06:39 AM, David Miller wrote:
>>> From: Stefan Hajnoczi <stefanha@redhat.com>
>>> Date: Thu, 10 Jan 2013 08:59:48 +0100
>>>
>>>> Multiqueue tun devices support detaching a tun_file from its tun_struct
>>>> and re-attaching at a later point in time.  This allows users to disable
>>>> a specific queue temporarily.
>>>>
>>>> ioctl(TUNSETIFF) allows the user to specify the network interface to
>>>> attach by name.  This means the user can attempt to attach to interface
>>>> "B" after detaching from interface "A".
>>>>
>>>> The driver is not designed to support this so check we are re-attaching
>>>> to the right tun_struct.  Failure to do so may lead to oops.
>>>>
>>>> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
>>> Applied.
>> Hi David:
>>
>> Any chance that I can have a respin on this patch, there's still a bug
>> after this patch. Or I just can send a patch on top?
> If I've applied it, there is no reverting.

Get it, will send patch on top.

Thanks
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Patch hide | download patch | download mbox

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index fbd106e..cf6da6e 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -491,6 +491,8 @@  static int tun_attach(struct tun_struct *tun, struct file *file)
 	err = -EINVAL;
 	if (rcu_dereference_protected(tfile->tun, lockdep_rtnl_is_held()))
 		goto out;
+	if (tfile->detached && tun != tfile->detached)
+		goto out;
 
 	err = -EBUSY;
 	if (!(tun->flags & TUN_TAP_MQ) && tun->numqueues == 1)