On 2019/10/15 1:57 上午, Cong Wang wrote:
On Sat, Oct 12, 2019 at 12:16 AM Zhiyuan Hou <[email protected]> wrote: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); + }Good catch! I don't want to be picky, but it seems this is only needed when redirecting from egress to ingress, right? That is, ingress to ingress, or ingress to egress is okay? If not, please fix all the cases while you are on it?
Sure. But I think this patch is also needed when redirecting from ingress to ingress. Because we cannot assure that a skb has null dst in ingress redirection path. For example, if redirecting a skb from loopback's ingress to other device's ingress, the skb will take a dst. As commit logs point out, skb with valid dst cannot be made routing decision in following process. original dst may cause skb loss or other unexpected behavior.
Thanks.
