Rusty Russell wrote:
> Add a IFF_VNET_HDR flag.  This uses the same ABI as virtio_net (ie. prepending
> struct virtio_net_hdr to packets) to indicate GSO and checksum information.
> 
> Signed-off-by: Rusty Russell <[EMAIL PROTECTED]>
> ---
>  drivers/net/tun.c      |   90 
> ++++++++++++++++++++++++++++++++++++++++++++++++-
>  include/linux/if_tun.h |    2 +
>  2 files changed, 91 insertions(+), 1 deletion(-)
> 
> diff -r d94590c1550a drivers/net/tun.c
> --- a/drivers/net/tun.c       Thu Jun 26 00:21:11 2008 +1000
> +++ b/drivers/net/tun.c       Thu Jun 26 00:21:59 2008 +1000
> @@ -63,6 +63,7 @@
>  #include <linux/if_tun.h>
>  #include <linux/crc32.h>
>  #include <linux/nsproxy.h>
> +#include <linux/virtio_net.h>
>  #include <net/net_namespace.h>
>  #include <net/netns/generic.h>
>  
> @@ -283,12 +284,24 @@ static __inline__ ssize_t tun_get_user(s
>       struct tun_pi pi = { 0, __constant_htons(ETH_P_IP) };
>       struct sk_buff *skb;
>       size_t len = count, align = 0;
> +     struct virtio_net_hdr gso = { 0 };
>  
>       if (!(tun->flags & TUN_NO_PI)) {
>               if ((len -= sizeof(pi)) > count)
>                       return -EINVAL;
>  
>               if(memcpy_fromiovec((void *)&pi, iv, sizeof(pi)))
> +                     return -EFAULT;
> +     }
> +
> +     if (tun->flags & TUN_VNET_HDR) {
> +             if ((len -= sizeof(gso)) > count)
> +                     return -EINVAL;
> +
> +             if (gso.hdr_len > len)
> +                     return -EINVAL;
> +
> +             if (memcpy_fromiovec((void *)&gso, iv, sizeof(gso)))
>                       return -EFAULT;
>       }

Unless I'm missing something the 'if (gso.hdr_len > len)' must be after
memcpy_fromiovec().

> @@ -322,8 +335,45 @@ static __inline__ ssize_t tun_get_user(s
>               break;
>       };
>  
> -     if (tun->flags & TUN_NOCHECKSUM)
> +     if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
> +             if (!skb_partial_csum_set(skb, gso.csum_start,
> +                                       gso.csum_offset)) {
> +                     tun->dev->stats.rx_dropped++;
> +                     kfree_skb(skb);
> +                     return -EINVAL;
> +             }
> +     } else if (tun->flags & TUN_NOCHECKSUM)
>               skb->ip_summed = CHECKSUM_UNNECESSARY;
> +
> +     if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
> +             pr_debug("GSO!\n");
> +             switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
> +             case VIRTIO_NET_HDR_GSO_TCPV4:
> +                     skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
> +                     break;
> +             case VIRTIO_NET_HDR_GSO_TCPV6:
> +                     skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
> +                     break;
> +             default:
> +                     tun->dev->stats.rx_dropped++;
> +                     kfree_skb(skb);
> +                     return -EINVAL;
> +             }

We should use stats.rx_frame_errors instead of stats.rx_dropped to indicated
that we dropped it because something was wrong with the framing (headers,
etc). Applies to both of the cases above.

> +
> +             if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
> +                     skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
> +
> +             skb_shinfo(skb)->gso_size = gso.gso_size;
> +             if (skb_shinfo(skb)->gso_size == 0) {
> +                     tun->dev->stats.rx_dropped++;
> +                     kfree_skb(skb);
> +                     return -EINVAL;
> +             }
Same here.

Everything else looks good.

Max

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