From mboxrd@z Thu Jan 1 00:00:00 1970 From: lepton Subject: Re: [PATCH RESEND] 2.6.22.6 networking [ipv4]: fix wrong destination when reply packetes Date: Fri, 21 Sep 2007 14:03:01 +0800 Message-ID: <20070921060301.GA6019@router.lepton.home> References: <20070921022335.GA2849@router.lepton.home> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: lepton , lkm , netdev@vger.kernel.org, netdev-owner@vger.kernel.org To: David Stevens Return-path: Received: from qb-out-0506.google.com ([72.14.204.237]:59643 "EHLO qb-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751907AbXIUGEJ (ORCPT ); Fri, 21 Sep 2007 02:04:09 -0400 Received: by qb-out-0506.google.com with SMTP id e11so554505qbe for ; Thu, 20 Sep 2007 23:04:08 -0700 (PDT) Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Now icmp_reply is only called by icmp_echo and icmp_timestamp ip_send_reply is only called by tcp_v4_send_reset and tcp_v4_send_ack I think in all situations the ip_hdr(skb)->saddr is set and should be the destination of reply packets. If using rt->rt_src as destination is correct in some situation, can anyone give me a example? I think perhaps it is a copy and paste from code like ip_build_and_send_pkt, but reply packets in these situations (icmp_echo and icmp_timestamp and tcp_v4_send_ack and tcp_v4_send_reset) is diffrent, I think we can just use ip_hdr(skb)->saddr as destination address. On Thu, Sep 20, 2007 at 09:35:09PM -0700, David Stevens wrote: > I'm not sure why it's using rt_src here, but there are relevant cases that > your description doesn't cover. For example, what happens if the source > is not set in the original packet? Does NAT affect this? > > You quote RFC text for ICMP echo and the case where the receiving machine > is the final destination, but you're modifying code that is used for all > ICMP > types and used for ICMP errors generated when acting as an intermediate > router. > > In ordinary cases, and certainly with ICMP echo when the source is set in > the original packet and no rewriting is going on (and the address is not > spoofed), > using the original source as the destination is fine. But have you tested > or > considered the other cases? > > +-DLS >