netdev - Re: [PATCH] net: Fix missing meta data in skb with vlan packet

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Date:   Mon, 15 Apr 2019 15:05:36 +0900
From:   Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
To:     Yuya Kusakabe <yuya.kusakabe@...il.com>
Cc:     davem@...emloft.net, taketarou2@...il.com, netdev@...r.kernel.org,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>
Subject: Re: [PATCH] net: Fix missing meta data in skb with vlan packet

Hi,
(CC: XDP maintainers)

On 2019/04/13 21:16, Yuya Kusakabe wrote:
> skb_reorder_vlan_header() should move XDP meta data with ethernet
> header if XDP meta data exists.
> 
> Signed-off-by: Yuya Kusakabe <yuya.kusakabe@...il.com>
> Signed-off-by: Takeru Hayasaka <taketarou2@...il.com>
> Co-developed-by: Takeru Hayasaka <taketarou2@...il.com>

Missing fixes tag

Fixes: de8f3a83b0a0 ("bpf: add meta pointer for direct access")

> ---
>  net/core/skbuff.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index ef2cd5712098..6bc663249c4c 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -5083,7 +5083,8 @@ EXPORT_SYMBOL_GPL(skb_gso_validate_mac_len);
> 
>  static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb)
>  {
> -       int mac_len;
> +       int mac_len, meta_len;
> +       void *meta;
> 
>         if (skb_cow(skb, skb_headroom(skb)) < 0) {
>                 kfree_skb(skb);
> @@ -5095,6 +5096,13 @@ static struct sk_buff
> *skb_reorder_vlan_header(struct sk_buff *skb)
>                 memmove(skb_mac_header(skb) + VLAN_HLEN, skb_mac_header(skb),
>                         mac_len - VLAN_HLEN - ETH_TLEN);
>         }
> +
> +       meta_len = skb_metadata_len(skb);
> +       if (meta_len) {

Since this is not used by non-XDP skb and skb path is slow-path for XDP
anyway, should add unlikely here in favor of non-XDP case?

> +               meta = skb_metadata_end(skb) - meta_len;
> +               memmove(meta + VLAN_HLEN, meta, meta_len);
> +       };
> +
>         skb->mac_header += VLAN_HLEN;
>         return skb;
>  }
> --
> 2.20.1
> 
> 

-- 
Toshiaki Makita