----- Original Message -----
> Now that UFO is split into v4 and v6 parts, we can bring
> back v4 support without any trouble.
>
> Continue to handle legacy applications by selecting the
> IPv6 fragment id but do not change the gso type. Thist
> makes sure that two legacy VMs may still communicate.
>
> Based on original work from Ben Hutchings.
>
> Fixes: 88e0e0e5aa7a ("drivers/net: Disable UFO through virtio")
> CC: Ben Hutchings <b...@decadent.org.uk>
> Signed-off-by: Vladislav Yasevich <vyase...@redhat.com>
> ---
> drivers/net/tun.c | 26 ++++++++++++++------------
> 1 file changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 9dd3746..8c32fca 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -175,7 +175,7 @@ struct tun_struct {
> struct net_device *dev;
> netdev_features_t set_features;
> #define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
> - NETIF_F_TSO6)
> + NETIF_F_TSO6|NETIF_F_UFO)
>
> int vnet_hdr_sz;
> int sndbuf;
> @@ -1152,20 +1152,15 @@ static ssize_t tun_get_user(struct tun_struct *tun,
> struct tun_file *tfile,
> skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
> break;
> case VIRTIO_NET_HDR_GSO_UDP:
> - {
> - static bool warned;
> -
> - if (!warned) {
> - warned = true;
> - netdev_warn(tun->dev,
> - "%s: using disabled UFO feature;
> please fix this program\n",
> - current->comm);
> - }
> skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
> - if (skb->protocol == htons(ETH_P_IPV6))
> + if (vlan_get_protocol(skb) == htons(ETH_P_IPV6)) {
This probably means UDPv6 with vlan does not work well, looks like another
independent fixe and also for stable.
> + /* This allows legacy application to work.
> + * Do not change the gso_type as it may
> + * not be upderstood by legacy applications.
> + */
Isn't this an issue that we use SKB_GSO_UDP for a UDPv6 packet? Especially
consider we want to fix UFOv6 in the future? We probably can use
SKB_GSO_UDP6 here and try to fix it in tun_put_user() if a legacy userspace
is detected.
> ipv6_proxy_select_ident(skb);
Question still for vlan, is network header correctly set here? Looks like
ipv6_proxy_select_ident() depends on correct network header to work.
> + }
> break;
> - }
> default:
> tun->dev->stats.rx_frame_errors++;
> kfree_skb(skb);
> @@ -1273,6 +1268,8 @@ static ssize_t tun_put_user(struct tun_struct *tun,
> gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
> else if (sinfo->gso_type & SKB_GSO_TCPV6)
> gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
> + else if (sinfo->gso_type & SKB_GSO_UDP)
> + gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
> else {
> pr_err("unexpected GSO type: "
> "0x%x, gso_size %d, hdr_len %d\n",
> @@ -1780,6 +1777,11 @@ static int set_offload(struct tun_struct *tun,
> unsigned long arg)
> features |= NETIF_F_TSO6;
> arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
> }
> +
> + if (arg & TUN_F_UFO) {
> + features |= NETIF_F_UFO;
> + arg &= ~TUN_F_UFO;
> + }
> }
>
> /* This gives the user a way to test for new features in future by
> --
> 1.9.3
>
> --
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