From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pankaj Gupta Subject: Re: [PATCH net-net 0/4] Increase the limit of tuntap queues Date: Mon, 24 Nov 2014 09:28:25 -0500 (EST) Message-ID: <1253769917.3166193.1416839305146.JavaMail.zimbra@redhat.com> References: <20141123104623.GA31915@redhat.com> <20141123.134323.1154795102254868842.davem@davemloft.net> <20141123203032.GA6286@redhat.com> <20141123.202321.1426718936320546377.davem@davemloft.net> <20141124080243.GD6286@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: David Miller , 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 To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20141124080243.GD6286@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org > On Sun, Nov 23, 2014 at 08:23:21PM -0500, David Miller wrote: > > From: "Michael S. Tsirkin" > > 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 > -- > MST > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >