netdev - Re: forwarded bridged packets enqueuing is broken

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Message-ID: <20191202161632.GO795@breakpoint.cc>
Date:   Mon, 2 Dec 2019 17:16:32 +0100
From:   Florian Westphal <fw@...len.de>
To:     Marco Oliverio <marco.oliverio@...aza.com>
Cc:     netfilter-devel@...r.kernel.org,
        Rocco Folino <notifications@...hub.com>,
        Florian Westphal <fw@...len.de>,
        netdev <netdev@...r.kernel.org>
Subject: Re: forwarded bridged packets enqueuing is broken

Marco Oliverio <marco.oliverio@...aza.com> wrote:
> We cannot enqueue userspace bridged forwarded packets (neither in the
> forward chain nor in the postrouting one):

[..]

> AFAIU forwarded bridge packets have a null dst entry in the first
> place, as they don't enter the ip stack, so skb_dst_force() returns
> false. The very same commit suggested to check skb_dst() before
> skb_dst_force(), doing that indeed fix the issue for us:
> 
> modified   net/netfilter/nf_queue.c
> @@ -174,7 +174,7 @@ static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state,
>  		goto err;
>  	}
>  
> -	if (!skb_dst_force(skb) && state->hook != NF_INET_PRE_ROUTING) {
> +	if (skb_dst(skb) && !skb_dst_force(skb)) {

Looks fine to me, please submit this formally.  Thanks!