From: "Michael S. Tsirkin" <mst@redhat•com>
To: David Miller <davem@davemloft•net>
Cc: pagupta@redhat•com, linux-kernel@vger•kernel.org,
netdev@vger•kernel.org, jasowang@redhat•com, dgibson@redhat•com,
vfalico@gmail•com, edumazet@google•com, vyasevic@redhat•com,
hkchu@google•com, wuzhy@linux•vnet.ibm.com, xemul@parallels•com,
therbert@google•com, bhutchings@solarflare•com, xii@google•com,
stephen@networkplumber•org, jiri@resnulli•us,
sergei.shtylyov@cogentembedded•com
Subject: Re: [PATCH net-net 0/4] Increase the limit of tuntap queues
Date: Mon, 24 Nov 2014 10:02:43 +0200 [thread overview]
Message-ID: <20141124080243.GD6286@redhat.com> (raw)
In-Reply-To: <20141123.202321.1426718936320546377.davem@davemloft.net>
On Sun, Nov 23, 2014 at 08:23:21PM -0500, David Miller wrote:
> From: "Michael S. Tsirkin" <mst@redhat•com>
> Date: Sun, 23 Nov 2014 22:30:32 +0200
>
> > qemu runs in the host, but it's unpriveledged: it gets
> > passed tun FDs by a priveledged daemon, and it only
> > has the rights to some operations,
> > in particular to attach and detach queues.
> >
> > The assumption always was that this operation is safe
> > and can't make kernel run out of resources.
>
> This creates a rather rediculous situation in my opinion.
>
> Configuring a network device is a privileged operation, the daemon
> should be setting this thing up.
>
> In no other context would we have to worry about something like this.
Right. Jason corrected me. I got it wrong:
what qemu does is TUNSETQUEUE and that needs to get a queue
that's already initialized by the daemon.
To create new queues daemon calls TUNSETIFF,
and that already can be used to create new devices,
so it's a priveledged operation.
This means it's safe to just drop the restriction,
exactly as you suggested originally.
--
MST
next prev parent reply other threads:[~2014-11-24 8:03 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-18 16:22 [PATCH net-net 0/4] Increase the limit of tuntap queues Pankaj Gupta
2014-11-18 16:22 ` [PATCH net-next 1/4] net: allow large number of rx queues Pankaj Gupta
2014-11-18 20:29 ` Cong Wang
2014-11-20 16:31 ` Pankaj Gupta
2014-11-18 16:22 ` [PATCH net-next 2/4] tuntap: Accept tuntap maximum number of queues as sysctl Pankaj Gupta
2014-11-18 16:22 ` [PATCH net-next 3/4] tuntap: reduce the size of tun_struct by using flex array Pankaj Gupta
2014-11-18 16:22 ` [PATCH net-next 4/4] tuntap: Increase the number of queues in tun Pankaj Gupta
2014-11-19 1:43 ` [PATCH net-net 0/4] Increase the limit of tuntap queues Alexei Starovoitov
2014-11-19 20:16 ` David Miller
2014-11-19 20:44 ` Michael S. Tsirkin
2014-11-23 5:22 ` Pankaj Gupta
2014-11-23 10:46 ` Michael S. Tsirkin
2014-11-23 18:43 ` David Miller
2014-11-23 20:30 ` Michael S. Tsirkin
2014-11-24 1:23 ` David Miller
2014-11-24 8:02 ` Michael S. Tsirkin [this message]
2014-11-24 14:28 ` Pankaj Gupta
2014-11-24 3:23 ` Jason Wang
2014-11-24 7:55 ` Michael S. Tsirkin
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