Subject: Re: [PATCH v8 5/6] net: ipv4, ipv6: run cgroup eBPF egress programs

From: Pablo Neira Ayuso <pablo-Cap9r6Oaw4JrovVCs/[email-masked]>
Date: Fri, 18 Nov 2016 13:37:32 +0100

On Thu, Nov 17, 2016 at 07:27:08PM +0100, Daniel Mack wrote:
[...]
> @@ -312,6 +314,12 @@ int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
>  	skb->dev = dev;
>  	skb->protocol = htons(ETH_P_IP);
>  
> +	ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
> +	if (ret) {
> +		kfree_skb(skb);
> +		return ret;
> +	}
> +
>  	/*
>  	 *	Multicasts are looped back for other local users
>  	 */
> @@ -364,12 +372,19 @@ int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
>  int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
>  {
>  	struct net_device *dev = skb_dst(skb)->dev;
> +	int ret;
>  
>  	IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
>  
>  	skb->dev = dev;
>  	skb->protocol = htons(ETH_P_IP);
>  
> +	ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
> +	if (ret) {
> +		kfree_skb(skb);
> +		return ret;
> +	}
> +
>  	return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
>  			    net, sk, skb, NULL, dev,
>  			    ip_finish_output,

Please, place this after the netfilter hook.

Since this new hook may mangle output packets, any mangling
potentially interfers and breaks conntrack.

Thank you.