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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 86F2BC433DB for ; Mon, 29 Mar 2021 10:31:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5D8666192B for ; Mon, 29 Mar 2021 10:31:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232158AbhC2Ka5 (ORCPT ); Mon, 29 Mar 2021 06:30:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49120 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231787AbhC2Kam (ORCPT ); Mon, 29 Mar 2021 06:30:42 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4DAD2C061574 for ; Mon, 29 Mar 2021 03:30:41 -0700 (PDT) From: Kurt Kanzenbach DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1617013839; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=4XUKuDY4UHoIwwqGebIX/nAu3rjgida9J3DZWeqzZOk=; b=2fvkoDbm1Klb1SxpmuG/xjgC/8cTCbQT4O4GYgx8REmaFCWkGPiuDSi9IMLwiNqJKwyVEn 89eV6KHoS8wDqXA73E4RMpLmLqMNtNV7S+gEEtAsQlhbo8cPA4G7CYSwFjz6CPzbcGYuUE 1EwsHXQ6zRZ3lRCDY4PljQVn/PPxXzOz3q4wnLM6p3dribTDLHHgDnRU1JJJGoMokOI8hy vkLVHBH2FrBiKLkGN/2pQE4PBq9plga91c/ltQZyxofgvRVEqqnuGhdb++/Wx6ZvMKGGzE JexUVJMOWtxfSoANkMr+2RdbWnM5dTpyIOpl6CSfTjxvQ7XwlvUKgOn5gLCJmA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1617013839; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=4XUKuDY4UHoIwwqGebIX/nAu3rjgida9J3DZWeqzZOk=; b=2o45cTZr+34whC8KM6kEq5wRmWQeM62L0gfP0dB7zPQnz54YbvoW1sG7u5n2gmsdImgIxe 8HcZJ5IjCvn0LRAA== To: Eric Dumazet Cc: "David S. Miller" , Jakub Kicinski , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Antoine Tenart , Wei Wang , Cong Wang , Taehee Yoo , Jesper Dangaard Brouer , Sebastian Andrzej Siewior , Willem de Bruijn , netdev Subject: Re: [PATCH net v2] net: Reset MAC header for direct packet transmission In-Reply-To: References: <20210329071716.12235-1-kurt@linutronix.de> Date: Mon, 29 Mar 2021 12:30:37 +0200 Message-ID: <878s661cc2.fsf@kurt> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Mon Mar 29 2021, Eric Dumazet wrote: > Note that last year, I addressed the issue differently in commit > 96cc4b69581db68efc9749ef32e9cf8e0160c509 > ("macvlan: do not assume mac_header is set in macvlan_broadcast()") > (amended with commit 1712b2fff8c682d145c7889d2290696647d82dab > "macvlan: use skb_reset_mac_header() in macvlan_queue_xmit()") > > My reasoning was that in TX path, when ndo_start_xmit() is called, MAC > header is essentially skb->data, > so I was hoping to _remove_ skb_reset_mac_header(skb) eventually from > the fast path (aka __dev_queue_xmit), > because most drivers do not care about MAC header, they just use skb->dat= a. > > I understand it is more difficult to review drivers instead of just > adding more code in __dev_direct_xmit() > > In hsr case, I do not really see why the existing check can not be > simply reworked ? It can be reworked, no problem. I just thought it might be better to add it to the generic code just in case there are more drivers suffering from the issue. > > mac_header really makes sense in input path, when some layer wants to > get it after it has been pulled. > > diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c > index ed82a470b6e154be28d7e53be57019bccd4a964d..cda495cb1471e23e6666c1f2e= 9d27a01694f997f > 100644 > --- a/net/hsr/hsr_forward.c > +++ b/net/hsr/hsr_forward.c > @@ -555,11 +555,7 @@ void hsr_forward_skb(struct sk_buff *skb, struct > hsr_port *port) > { > struct hsr_frame_info frame; > > - if (skb_mac_header(skb) !=3D skb->data) { > - WARN_ONCE(1, "%s:%d: Malformed frame (port_src %s)\n", > - __FILE__, __LINE__, port->dev->name); > - goto out_drop; > - } > + skb_reset_mac_header(skb); hsr_forward_skb() has four call sites. Three of them make sure that the header is properly set. The Tx path does not. So, maybe something like below? Thanks, Kurt diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c index 7444ec6e298e..bfcdc75fc01e 100644 =2D-- a/net/hsr/hsr_device.c +++ b/net/hsr/hsr_device.c @@ -217,6 +217,7 @@ static netdev_tx_t hsr_dev_xmit(struct sk_buff *skb, st= ruct net_device *dev) master =3D hsr_port_get_hsr(hsr, HSR_PT_MASTER); if (master) { skb->dev =3D master->dev; + skb_reset_mac_header(skb); hsr_forward_skb(skb, master); } else { atomic_long_inc(&dev->tx_dropped); diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c index ed82a470b6e1..b218e4594009 100644 =2D-- a/net/hsr/hsr_forward.c +++ b/net/hsr/hsr_forward.c @@ -555,12 +555,6 @@ void hsr_forward_skb(struct sk_buff *skb, struct hsr_p= ort *port) { struct hsr_frame_info frame; =2D if (skb_mac_header(skb) !=3D skb->data) { =2D WARN_ONCE(1, "%s:%d: Malformed frame (port_src %s)\n", =2D __FILE__, __LINE__, port->dev->name); =2D goto out_drop; =2D } =2D --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEooWgvezyxHPhdEojeSpbgcuY8KYFAmBhrE0ACgkQeSpbgcuY 8KY45BAAkrwIlJ6AePjrZvfHrFrKpQBbM8J9KWGJ3vBHURWi1ngwZEQ1SBHc62E4 ujwgQiirw28mRMkVdfYBC79cKfNAcfvwFvY11KTEqek9fPxWM74NPfNJt1vItwCf wSDnUbgpEjR+DChzYJUGg8HL2BDNg5mXNu3rlW59OrBup2htDRYDX+KjAgAqkwRf bt8vKl/wdU9C7GvsRiB5sasIpp3A6z7YHXhZYwMqQ5ZsWjQPS9wB8vxhFdn7FPkr +cbftDG5teQaEB6ktZGPbBQtCjs09r+zHTvaQJnRy0iwNzozmQeUDrsFfZFybv/b Vq9Pkp8J9lS8K/1DfxQIURmxii067xbFo3XJ+vO3H7gE5wmR2DBNEiBaMr70tXCP nLDf4cv+7sNlZnzEDJ2+/a6p+ZoEgwpNAHnt7EkmIgc/nfrxPvOCVs90+ZVsB6Lw SVI0KkHT81Z9M2vEFif8AeqkpZHmBHkIKpWnbhaOUwdszBFSys4G37w2tkOllSfv h598jMlt3RBycew9LZzrzL8fAUHFrjeQiIMs5C/8enwdhQ1G25WPHUy8eiZp+2vb Q+OUiwtIA3RRoqTXvl2HZfKALrx4yLnrbd1iDq8d7lC1AE7fsxVjvMFWloSQsy5/ fo58Vtbn/d9SoKFvu8ViSKFBmC55SI+JdJiV0He+LhSddwmJ4M0= =wiOT -----END PGP SIGNATURE----- --=-=-=--