From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH] tun: orphan an skb on tx Date: Tue, 13 Apr 2010 23:25:48 +0300 Message-ID: <20100413202548.GA3582@redhat.com> References: <20100413145944.GA7716@redhat.com> <4BC48F79.5090409@siemens.com> <1271176838.16881.537.camel@edumazet-laptop> <20100413173919.GC26011@redhat.com> <1271183463.16881.545.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Jan Kiszka , "David S. Miller" , Herbert Xu , Paul Moore , David Woodhouse , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , qemu-devel To: Eric Dumazet Return-path: Received: from mx1.redhat.com ([209.132.183.28]:29416 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753143Ab0DMUai (ORCPT ); Tue, 13 Apr 2010 16:30:38 -0400 Content-Disposition: inline In-Reply-To: <1271183463.16881.545.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Apr 13, 2010 at 08:31:03PM +0200, Eric Dumazet wrote: > Le mardi 13 avril 2010 =E0 20:39 +0300, Michael S. Tsirkin a =E9crit = : >=20 > > > When a socket with inflight tx packets is closed, we dont block t= he > > > close, we only delay the socket freeing once all packets were del= ivered > > > and freed. > > >=20 > >=20 > > Which is wrong, since this is under userspace control, so you get > > unkillable processes. > >=20 >=20 > We do not get unkillable processes, at least with sockets I was think= ing > about (TCP/UDP ones). >=20 > Maybe tun sockets can behave the same ? Looks like that's what my patch does: ip_rcv seems to call skb_orphan too. > Herbert Acked your patch, so I guess its OK, but I think it can be > dangerous. > Anyway my feeling is that we try to add various mechanisms to keep a > hostile user flooding another one. >=20 > For example, UDP got memory accounting quite recently, and we added > socket backlog limits very recently. It was considered not needed few > years ago. >=20