From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6631FC433E2 for ; Mon, 18 May 2020 06:30:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DDD92070A for ; Mon, 18 May 2020 06:30:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727814AbgERGar (ORCPT ); Mon, 18 May 2020 02:30:47 -0400 Received: from verein.lst.de ([213.95.11.211]:36998 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726543AbgERGaq (ORCPT ); Mon, 18 May 2020 02:30:46 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 970DF68AFE; Mon, 18 May 2020 08:30:43 +0200 (CEST) Date: Mon, 18 May 2020 08:30:43 +0200 From: Christoph Hellwig To: David Miller Cc: hch@lst.de, kuba@kernel.org, kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/4] ipv6: symbol_get to access a sit symbol Message-ID: <20200518063043.GA19046@lst.de> References: <20200514145101.3000612-5-hch@lst.de> <20200514.175355.167885308958584692.davem@davemloft.net> <20200515063324.GA31377@lst.de> <20200516.135548.2079608042651975047.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200516.135548.2079608042651975047.davem@davemloft.net> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sat, May 16, 2020 at 01:55:48PM -0700, David Miller wrote: > From: Christoph Hellwig > Date: Fri, 15 May 2020 08:33:24 +0200 > > > My initial plan was to add a ->tunnel_ctl method to the net_device_ops, > > and lift the copy_{to,from}_user for SIOCADDTUNNEL, SIOCCHGTUNNEL, > > SIOCDELTUNNEL and maybe SIOCGETTUNNEL to net/socket.c. But that turned > > out to have two problems: > > > > - first these ioctls names use SIOCDEVPRIVATE range, that can also > > be implemented by other drivers > > - the ip_tunnel_parm struture is only used by the ipv4 tunneling > > drivers (including sit), the "real" ipv6 tunnels use a > > ip6_tnl_parm or ip6_tnl_parm structure instead > > Yes, this is the core of the problem, the user provided data's type > is unknown until we are very deep in the call chains. > > I wonder if there is some clever way to propagate this size value > "up"? As far as I can tell the only information vectors is the net_device structure or its op vector. But even then we have the problem that other devices use the SIOCDEVPRIVATE range for something else. I'll look into implenenting the tunnel_ctl method just for kernel callers (plus maybe a generic helper for the ioctl), and we'll see if you like that better.