lkml.org 
[lkml]   [2022]   [Feb]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH net v3] gso: do not skip outer ip header in case of ipip and net_failover
On Fri, Feb 18, 2022 at 6:36 AM Tao Liu <thomas.liu@ucloud.cn> wrote:
>
> We encounter a tcp drop issue in our cloud environment. Packet GROed in
> host forwards to a VM virtio_net nic with net_failover enabled. VM acts
> as a IPVS LB with ipip encapsulation. The full path like:
> host gro -> vm virtio_net rx -> net_failover rx -> ipvs fullnat
> -> ipip encap -> net_failover tx -> virtio_net tx
>
> When net_failover transmits a ipip pkt (gso_type = 0x0103, which means
> SKB_GSO_TCPV4, SKB_GSO_DODGY and SKB_GSO_IPXIP4), there is no gso
> did because it supports TSO and GSO_IPXIP4. But network_header points to
> inner ip header.
>
> Call Trace:
> tcp4_gso_segment ------> return NULL
> inet_gso_segment ------> inner iph, network_header points to
> ipip_gso_segment
> inet_gso_segment ------> outer iph
> skb_mac_gso_segment
>
> Afterwards virtio_net transmits the pkt, only inner ip header is modified.
> And the outer one just keeps unchanged. The pkt will be dropped in remote
> host.
>
> Call Trace:
> inet_gso_segment ------> inner iph, outer iph is skipped
> skb_mac_gso_segment
> __skb_gso_segment
> validate_xmit_skb
> validate_xmit_skb_list
> sch_direct_xmit
> __qdisc_run
> __dev_queue_xmit ------> virtio_net
> dev_hard_start_xmit
> __dev_queue_xmit ------> net_failover
> ip_finish_output2
> ip_output
> iptunnel_xmit
> ip_tunnel_xmit
> ipip_tunnel_xmit ------> ipip
> dev_hard_start_xmit
> __dev_queue_xmit
> ip_finish_output2
> ip_output
> ip_forward
> ip_rcv
> __netif_receive_skb_one_core
> netif_receive_skb_internal
> napi_gro_receive
> receive_buf
> virtnet_poll
> net_rx_action
>
> The root cause of this issue is specific with the rare combination of
> SKB_GSO_DODGY and a tunnel device that adds an SKB_GSO_ tunnel option.
> SKB_GSO_DODGY is set from external virtio_net. We need to reset network
> header when callbacks.gso_segment() returns NULL.
>
> This patch also includes ipv6_gso_segment(), considering SIT, etc.
>
> Fixes: cb32f511a70b ("ipip: add GSO/TSO support")
> Signed-off-by: Tao Liu <thomas.liu@ucloud.cn>

Reviewed-by: Willem de Bruijn <willemb@google.com>

\
 
 \ /
  Last update: 2022-02-20 17:33    [W:0.065 / U:0.380 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site