From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [PATCH net 1/2] net: dev_queue_xmit_nit: fix skb->vlan_tci field value Date: Tue, 8 Jan 2013 21:14:50 +0100 Message-ID: <20130108201450.GD1621@minipsycho.orion> References: <1357671093-9605-1-git-send-email-dborkman@redhat.com> <1357671093-9605-2-git-send-email-dborkman@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , netdev@vger.kernel.org, Eric Dumazet , Ani Sinha , Jiri Pirko To: Daniel Borkmann Return-path: Received: from mail-we0-f173.google.com ([74.125.82.173]:65313 "EHLO mail-we0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751336Ab3AHUOz (ORCPT ); Tue, 8 Jan 2013 15:14:55 -0500 Received: by mail-we0-f173.google.com with SMTP id z2so649717wey.4 for ; Tue, 08 Jan 2013 12:14:54 -0800 (PST) Content-Disposition: inline In-Reply-To: <1357671093-9605-2-git-send-email-dborkman@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: Tue, Jan 08, 2013 at 07:51:32PM CET, dborkman@redhat.com wrote: >VLAN packets that are locally injected through taps will loose their >skb->vlan_tci value when they pass dev_hard_start_xmit and get looped >back to a packet sniffer via dev_queue_xmit_nit. Besides others, this >meta data is used in Linux socket filtering for VLANs. Tested with a >VLAN ancillary ops filter. > >Patch is based on a previous version by Jiri Pirko. > >Cc: Eric Dumazet >Cc: Ani Sinha >Cc: Jiri Pirko >Reported-by: Paul Pearce >Signed-off-by: Daniel Borkmann >--- > net/core/dev.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > >diff --git a/net/core/dev.c b/net/core/dev.c >index 515473e..723dcd0 100644 >--- a/net/core/dev.c >+++ b/net/core/dev.c >@@ -1775,6 +1775,19 @@ static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev) > struct packet_type *ptype; > struct sk_buff *skb2 = NULL; > struct packet_type *pt_prev = NULL; >+ struct ethhdr *ehdr; >+ >+ /* Network taps could make use of skb->vlan_tci, which got wiped >+ * out. Hence, we need to reset it correctly. >+ */ >+ skb_reset_mac_header(skb); >+ ehdr = eth_hdr(skb); >+ >+ if (ehdr->h_proto == __constant_htons(ETH_P_8021Q)) { >+ skb2 = vlan_untag(skb); >+ if (likely(skb2)) >+ skb = skb2; >+ } Hmm, nitpick, I think that better would be to do: skb = vlan_untag(skb); if (unlikely(!skb)) return; I believe that better is to deliver skbs in consistent way and to do not deliver at all in case of -ENOMEM