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Date:      Mon, 09 Jul 2012 13:52:15 -0700
From:      Xin Li <delphij@delphij.net>
To:        Mikolaj Golub <trociny@freebsd.org>
Cc:        "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net>, d@delphij.net, FreeBSD virtualization mailing list <freebsd-virtualization@FreeBSD.org>
Subject:   Re: GPF when doing jail -r, possibly an use-after-free
Message-ID:  <4FFB447F.6080508@delphij.net>
In-Reply-To: <86wr2cveys.fsf@kopusha.home.net>
References:  <4FF32FC4.6020701@delphij.net> <86wr2kau38.fsf@in138.ua3> <4FF5E87C.2020908@delphij.net> <86r4sqasrt.fsf@kopusha.home.net> <672D93D3-D4B1-432E-AE53-98E6C05B8BE4@lists.zabbadoz.net> <86zk7da10y.fsf@in138.ua3> <E909B0C0-F4DE-4110-B151-98FAC9330B82@lists.zabbadoz.net> <86obnqq94x.fsf@kopusha.home.net> <50CFED43-7789-4F27-9EC7-85268B7F23D4@lists.zabbadoz.net> <86liit8ocs.fsf@in138.ua3> <A8594672-5F62-4809-BBE7-7C2C3FAFE3C3@lists.zabbadoz.net> <86wr2cveys.fsf@kopusha.home.net>

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On 07/09/12 13:47, Mikolaj Golub wrote:
> 
> On Mon, 9 Jul 2012 06:07:05 +0000 Bjoern A. Zeeb wrote:
> 
> BAZ> On 9. Jul 2012, at 06:01 , Mikolaj Golub wrote:
> 
>>> 
>>> On Sun, 8 Jul 2012 20:52:55 +0000 Bjoern A. Zeeb wrote:
>>> 
>>> BAZ> Situation 1)
>>> 
>>> BAZ>         epairNa is in base, eiparNb is jail foo BAZ>
>>> stop jail foo: jail -r foo BAZ>         both epairN[ab] will
>>> live in base and can be destiryed without vnet switching
>>> 
>>> BAZ> Situation 2)
>>> 
>>> BAZ>         epairNa is in base, eiparNb is jail foo BAZ>
>>> you are in jail foo and type epairNb destroy;  that should not
>>> be allowed
>>> 
>>> BAZ> Situation 3)
>>> 
>>> BAZ>         epairNa is in base, eiparNb is jail foo BAZ>
>>> you are in base and type ifconfig epairNa destroy
>>> 
>>> BAZ>         This is your case ...  I am not sure what I'd
>>> expect in this case, BAZ>         especailly given epair is
>>> special...  You probably are right. BAZ>         Ideally I'd
>>> not allow it to be destroyed unless both are in the BAZ>
>>> if_home_vnet.  However it seems we allow this; so in that case 
>>> BAZ>         I definitively make sure to use the
>>> CURVNET_SET_QUIET() version BAZ>         to avoid the expected
>>> noise otherwise.
>>> 
>>> It looks like epair was expected to allow this, because in
>>> non-patched version it already did switching before freeing the
>>> interface. It just did not switch bere detaching.
>>> 
>>> CURVNET_SET_QUIET() is used in the current version of the patch
>>> so I suppose I can commit it.
>>> 
>>> But if you think that just not allowing to destroy unless both
>>> ends are in the f_home_vnet is a preferred solution and it is
>>> not late to change this I can provide the patch.
> 
> BAZ> Get it in for now; it helps people.  We should keep the other
> things in mind and BAZ> write down a proper policy; it's more
> interesting as you can do other things with BAZ> cloners you can
> create inside a vnet as well, today and later.
> 
> Thank you for the discussion. The patch is committed.

Thanks!

Cheers,
- -- 
Xin LI <delphij@delphij.net>	https://www.delphij.net/
FreeBSD - The Power to Serve!		Live free or die
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