Re: cgroup filter on physics interface can't control container

[Libo Chen]

ping...

On 2013/12/9 10:32, Libo Chen wrote:
> hello network hackers,
> 
> 	A linux container was builded with veth pair(veth0 inside container, veth1 outside container),
> 
> the config as below:
> 
>   lxc.network.type = veth
>   lxc.network.flags = up
>   lxc.network.link = br0  // base on eth0
>   lxc.network.name = eth0
>   lxc.network.ipv4 = 128.5.130.26/24
> 
> then I use tc command with cgroup filter on veth0, it works well. But when setting on eth0, it doesn`t work.
> 
> The reason is dev_forward_skb() in veth_xmit will call skb_scrub_packet and clean all information including skb->sk
> in the skb, so if cls_cgroup_classify is working in serving softirq state, it will return failer, see below:
> 
> 	if (in_serving_softirq()) {
> 		/* If there is an sk_classid we'll use that. */
> 		if (!skb->sk)
> 			return -1;
> 		classid = skb->sk->sk_classid;
> 	}
> 
> 
> Qdisc with cgroup filter on physics interface can not control a container network, it is disappointed.
> 
> we can save sk_classid before skb_scrub_packet and restore it after that. Is it reasonable?  or any way to achieve this?
> 
> thanks,
> Libo
> 


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