On 10/12/19 12:16 AM, Zhiyuan Hou wrote:
> In act_mirred's ingress redirection, if the skb's dst_entry is valid
> when call function netif_receive_skb, the fllowing l3 stack process
> (ip_rcv_finish_core) will check dst_entry and skip the routing
> decision. Using the old dst_entry is unexpected and may discard the
> skb in some case. For example dst->dst_input points to dst_discard.
>
> This patch drops the skb's dst_entry before calling netif_receive_skb
> so that the skb can be made routing decision like a normal ingress
> skb.
>
> Signed-off-by: Zhiyuan Hou <zhiyuan2...@linux.alibaba.com>
> ---
> net/sched/act_mirred.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
> index 9ce073a05414..6108a64c0cd5 100644
> --- a/net/sched/act_mirred.c
> +++ b/net/sched/act_mirred.c
> @@ -18,6 +18,7 @@
> #include <linux/gfp.h>
> #include <linux/if_arp.h>
> #include <net/net_namespace.h>
> +#include <net/dst.h>
> #include <net/netlink.h>
> #include <net/pkt_sched.h>
> #include <net/pkt_cls.h>
> @@ -298,8 +299,10 @@ static int tcf_mirred_act(struct sk_buff *skb, const
> struct tc_action *a,
>
> if (!want_ingress)
> err = dev_queue_xmit(skb2);
> - else
> + else {
> + skb_dst_drop(skb2);
> err = netif_receive_skb(skb2);
> + }
>
> if (err) {
> out:
>
Why is dst_discard used ?
This could actually drop packets, for loopback.
A Fixes: tag would tremendously help, I wonder if you are not working around
the other issue Wei was tracking yesterday (
https://www.spinics.net/lists/netdev/msg604397.html )
