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Message-ID: <BANLkTikjdz+LkavRiuqdDNS6+djAer-a0A@mail.gmail.com>
Date:	Fri, 3 Jun 2011 09:04:12 +0530
From:	padmanabh ratnakar <pratnakarlx@...il.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	David Miller <davem@...emloft.net>,
	shemminger@...ux-foundation.org, greearb@...delatech.com,
	nicolas.2p.debian@...il.com, jpirko@...hat.com, xiaosuo@...il.com,
	netdev@...r.kernel.org, kaber@...sh.net, fubar@...ibm.com,
	eric.dumazet@...il.com, andy@...yhouse.net, jesse@...ira.com
Subject: Re: [PATCH] vlan: Fix the ingress VLAN_FLAG_REORDER_HDR check v2

Doesnt __vlan_put_tag()/vlan_insert_tag() depend on skb->data pointing
to ethernet header.
Is'nt the skb->data pointing past ethernet header in netif_receive_skb().
Am I missing anything?
Regards,
Padmanabh


On Thu, Jun 2, 2011 at 6:33 PM, Eric W. Biederman <ebiederm@...ssion.com> wrote:
>
> Testing of VLAN_FLAG_REORDER_HDR does not belong in vlan_untag
> but rather in vlan_do_receive.  Otherwise the vlan header
> will not be properly put on the packet in the case of
> vlan header accelleration.
>
> As we remove the check from vlan_check_reorder_header
> rename it vlan_reorder_header to keep the naming clean.
>
> Fix up the skb->pkt_type early so we don't look at the packet
> after adding the vlan tag, which guarantees we don't goof
> and look at the wrong field.
>
> Use a simple if statement instead of a complicated switch
> statement to decided that we need to increment rx_stats
> for a multicast packet.
>
> Hopefully at somepoint we will just declare the case where
> VLAN_FLAG_REORDER_HDR is cleared as unsupported and remove
> the code.  Until then this keeps it working correctly.
>
> Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
> ---
>  include/linux/if_vlan.h |   25 ++++++++++++++++++++--
>  net/8021q/vlan_core.c   |   50 ++++++++++++++++++++++------------------------
>  2 files changed, 46 insertions(+), 29 deletions(-)
>
> diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
> index 290bd8a..821f0e3 100644
> --- a/include/linux/if_vlan.h
> +++ b/include/linux/if_vlan.h
> @@ -220,7 +220,7 @@ static inline int vlan_hwaccel_receive_skb(struct sk_buff *skb,
>  }
>
>  /**
> - * __vlan_put_tag - regular VLAN tag inserting
> + * vlan_insert_tag - regular VLAN tag inserting
>  * @skb: skbuff to tag
>  * @vlan_tci: VLAN TCI to insert
>  *
> @@ -229,8 +229,10 @@ static inline int vlan_hwaccel_receive_skb(struct sk_buff *skb,
>  *
>  * Following the skb_unshare() example, in case of error, the calling function
>  * doesn't have to worry about freeing the original skb.
> + *
> + * Does not change skb->protocol so this function can be used during receive.
>  */
> -static inline struct sk_buff *__vlan_put_tag(struct sk_buff *skb, u16 vlan_tci)
> +static inline struct sk_buff *vlan_insert_tag(struct sk_buff *skb, u16 vlan_tci)
>  {
>        struct vlan_ethhdr *veth;
>
> @@ -250,8 +252,25 @@ static inline struct sk_buff *__vlan_put_tag(struct sk_buff *skb, u16 vlan_tci)
>        /* now, the TCI */
>        veth->h_vlan_TCI = htons(vlan_tci);
>
> -       skb->protocol = htons(ETH_P_8021Q);
> +       return skb;
> +}
>
> +/**
> + * __vlan_put_tag - regular VLAN tag inserting
> + * @skb: skbuff to tag
> + * @vlan_tci: VLAN TCI to insert
> + *
> + * Inserts the VLAN tag into @skb as part of the payload
> + * Returns a VLAN tagged skb. If a new skb is created, @skb is freed.
> + *
> + * Following the skb_unshare() example, in case of error, the calling function
> + * doesn't have to worry about freeing the original skb.
> + */
> +static inline struct sk_buff *__vlan_put_tag(struct sk_buff *skb, u16 vlan_tci)
> +{
> +       skb = vlan_insert_tag(skb, vlan_tci);
> +       if (skb)
> +               skb->protocol = htons(ETH_P_8021Q);
>        return skb;
>  }
>
> diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
> index 41495dc..735c818 100644
> --- a/net/8021q/vlan_core.c
> +++ b/net/8021q/vlan_core.c
> @@ -23,6 +23,20 @@ bool vlan_do_receive(struct sk_buff **skbp)
>                return false;
>
>        skb->dev = vlan_dev;
> +       if (skb->pkt_type == PACKET_OTHERHOST) {
> +               /* Our lower layer thinks this is not local, let's make sure.
> +                * This allows the VLAN to have a different MAC than the
> +                * underlying device, and still route correctly. */
> +               if (!compare_ether_addr(eth_hdr(skb)->h_dest,
> +                                       vlan_dev->dev_addr))
> +                       skb->pkt_type = PACKET_HOST;
> +       }
> +
> +       if (unlikely(!(vlan_dev_info(vlan_dev)->flags & VLAN_FLAG_REORDER_HDR))) {
> +               skb = *skbp = vlan_insert_tag(skb, skb->vlan_tci);
> +               if (!skb)
> +                       return false;
> +       }
>        skb->priority = vlan_get_ingress_priority(vlan_dev, skb->vlan_tci);
>        skb->vlan_tci = 0;
>
> @@ -31,22 +45,8 @@ bool vlan_do_receive(struct sk_buff **skbp)
>        u64_stats_update_begin(&rx_stats->syncp);
>        rx_stats->rx_packets++;
>        rx_stats->rx_bytes += skb->len;
> -
> -       switch (skb->pkt_type) {
> -       case PACKET_BROADCAST:
> -               break;
> -       case PACKET_MULTICAST:
> +       if (skb->pkt_type == PACKET_MULTICAST)
>                rx_stats->rx_multicast++;
> -               break;
> -       case PACKET_OTHERHOST:
> -               /* Our lower layer thinks this is not local, let's make sure.
> -                * This allows the VLAN to have a different MAC than the
> -                * underlying device, and still route correctly. */
> -               if (!compare_ether_addr(eth_hdr(skb)->h_dest,
> -                                       vlan_dev->dev_addr))
> -                       skb->pkt_type = PACKET_HOST;
> -               break;
> -       }
>        u64_stats_update_end(&rx_stats->syncp);
>
>        return true;
> @@ -89,17 +89,15 @@ gro_result_t vlan_gro_frags(struct napi_struct *napi, struct vlan_group *grp,
>  }
>  EXPORT_SYMBOL(vlan_gro_frags);
>
> -static struct sk_buff *vlan_check_reorder_header(struct sk_buff *skb)
> +static struct sk_buff *vlan_reorder_header(struct sk_buff *skb)
>  {
> -       if (vlan_dev_info(skb->dev)->flags & VLAN_FLAG_REORDER_HDR) {
> -               if (skb_cow(skb, skb_headroom(skb)) < 0)
> -                       skb = NULL;
> -               if (skb) {
> -                       /* Lifted from Gleb's VLAN code... */
> -                       memmove(skb->data - ETH_HLEN,
> -                               skb->data - VLAN_ETH_HLEN, 12);
> -                       skb->mac_header += VLAN_HLEN;
> -               }
> +       if (skb_cow(skb, skb_headroom(skb)) < 0)
> +               skb = NULL;
> +       if (skb) {
> +               /* Lifted from Gleb's VLAN code... */
> +               memmove(skb->data - ETH_HLEN,
> +                       skb->data - VLAN_ETH_HLEN, 12);
> +               skb->mac_header += VLAN_HLEN;
>        }
>        return skb;
>  }
> @@ -161,7 +159,7 @@ struct sk_buff *vlan_untag(struct sk_buff *skb)
>        skb_pull_rcsum(skb, VLAN_HLEN);
>        vlan_set_encap_proto(skb, vhdr);
>
> -       skb = vlan_check_reorder_header(skb);
> +       skb = vlan_reorder_header(skb);
>        if (unlikely(!skb))
>                goto err_free;
>
> --
> 1.7.5.1.217.g4e3aa
>
> --
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