Subject: Re: [PATCH net-net 0/4] Increase the limit of tuntap queues

From: Pankaj Gupta <[email-masked]>
Date: Mon, 24 Nov 2014 09:28:25 -0500 (EST)

> On Sun, Nov 23, 2014 at 08:23:21PM -0500, David Miller wrote:
> > From: "Michael S. Tsirkin" <[email-masked]>
> > 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.

I will drop patch2 to add sysctl entry and and will send a v2 with other 
patches.

Thanks,
Pankaj

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