From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: Sending undersized ARP packets with VXLAN L3 interface Date: Wed, 27 Aug 2014 13:52:03 -0400 Message-ID: <53FE1AC3.5030409@gmail.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: netdev To: Cong Wang , Martin Rusko Return-path: Received: from mail-qg0-f45.google.com ([209.85.192.45]:37890 "EHLO mail-qg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750908AbaH0RwI (ORCPT ); Wed, 27 Aug 2014 13:52:08 -0400 Received: by mail-qg0-f45.google.com with SMTP id f51so596049qge.4 for ; Wed, 27 Aug 2014 10:52:07 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 08/27/2014 01:28 PM, Cong Wang wrote: > On Wed, Aug 27, 2014 at 10:06 AM, Martin Rusko wrote: >> >> I'm wondering, where is the proper place to fix this. Should >> arp_create() function allocate skb big enough to produce ethernet >> frame with at least minimum size? Or is it somewhere in NIC drivers >> where small packets are padded with zeros? > > Drivers do that, for example e1000: > > /* On PCI/PCI-X HW, if packet size is less than ETH_ZLEN, > * packets may get corrupted during padding by HW. > * To WA this issue, pad all small packets manually. > */ > if (skb->len < ETH_ZLEN) { > if (skb_pad(skb, ETH_ZLEN - skb->len)) > return NETDEV_TX_OK; > skb->len = ETH_ZLEN; > skb_set_tail_pointer(skb, ETH_ZLEN); > } I think vxlan needs something like this: From: Vladislav Yasevich Date: Wed, 27 Aug 2014 13:39:32 -0400 Subject: [PATCH] vxlan: Pad short ethernet frames. If sending short ethernet frames from the vxlan device, pad them to minimum size so they can be forwarded after decapsulation. Reported-by: Martin Rusko Signed-off-by: Vladislav Yasevich --- drivers/net/vxlan.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 1fb7b37..48267d4 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -1939,6 +1939,14 @@ static netdev_tx_t vxlan_xmit(struct sk_buff *skb, struct net_device *dev) #endif } + /* Pad short frames so they can be forwarded after decapsulation */ + if (skb->len < ETH_ZLEN) { + if (skb_pad(skb, ETH_ZLEN - skb->len)) + return NETDEV_TX_OK; + skb->len = ETH_ZLEN; + skb_set_tail_pointer(skb, ETH_ZLEN); + } + f = vxlan_find_mac(vxlan, eth->h_dest); did_rsc = false; -- 1.9.3