From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753478Ab0DMUak (ORCPT ); Tue, 13 Apr 2010 16:30:40 -0400 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 Date: Tue, 13 Apr 2010 23:25:48 +0300 From: "Michael S. Tsirkin" To: Eric Dumazet Cc: Jan Kiszka , "David S. Miller" , Herbert Xu , Paul Moore , David Woodhouse , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , qemu-devel Subject: Re: [PATCH] tun: orphan an skb on tx 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-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1271183463.16881.545.camel@edumazet-laptop> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 13, 2010 at 08:31:03PM +0200, Eric Dumazet wrote: > Le mardi 13 avril 2010 à 20:39 +0300, Michael S. Tsirkin a écrit : > > > > When a socket with inflight tx packets is closed, we dont block the > > > close, we only delay the socket freeing once all packets were delivered > > > and freed. > > > > > > > Which is wrong, since this is under userspace control, so you get > > unkillable processes. > > > > We do not get unkillable processes, at least with sockets I was thinking > about (TCP/UDP ones). > > 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. > > For example, UDP got memory accounting quite recently, and we added > socket backlog limits very recently. It was considered not needed few > years ago. > From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1O1mkm-00087l-5X for qemu-devel@nongnu.org; Tue, 13 Apr 2010 16:30:36 -0400 Received: from [140.186.70.92] (port=51179 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1O1mkk-00087I-DU for qemu-devel@nongnu.org; Tue, 13 Apr 2010 16:30:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1O1mki-0008C3-QB for qemu-devel@nongnu.org; Tue, 13 Apr 2010 16:30:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:23622) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1O1mkh-0008Bo-ST for qemu-devel@nongnu.org; Tue, 13 Apr 2010 16:30:32 -0400 Date: Tue, 13 Apr 2010 23:25:48 +0300 From: "Michael S. Tsirkin" 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-Disposition: inline In-Reply-To: <1271183463.16881.545.camel@edumazet-laptop> Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] Re: [PATCH] tun: orphan an skb on tx List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Dumazet Cc: Paul Moore , David Woodhouse , Jan Kiszka , "linux-kernel@vger.kernel.org" , qemu-devel , Herbert Xu , "netdev@vger.kernel.org" , "David S. Miller" 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 the > > > close, we only delay the socket freeing once all packets were deliv= ered > > > 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 thinkin= g > 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