netdev - Re: [PATCH,v2 net-next] ipvs: skb_orphan in case of forwarding

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Date:	Mon, 6 Jul 2015 01:13:06 +0300 (EEST)
From:	Julian Anastasov <ja@....bg>
To:	Alex Gartrell <agartrell@...com>
cc:	horms@...ge.net.au, lvs-devel@...r.kernel.org,
	netdev@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH,v2 net-next] ipvs: skb_orphan in case of forwarding


	Hello,

On Sun, 5 Jul 2015, Alex Gartrell wrote:

> It is possible that we bind against a local socket in early_demux when we
> are actually going to want to forward it.  In this case, the socket serves
> no purpose and only serves to confuse things (particularly functions which
> implicitly expect sk_fullsock to be true, like ip_local_out).
> Additionally, skb_set_owner_w is totally broken for non full-socks.
> 
> Signed-off-by: Alex Gartrell <agartrell@...com>

	Thanks for fixing this problem!

Acked-by: Julian Anastasov <ja@....bg>

	May be the patch fixes crashes? If yes, Simon
should apply it for ipvs/net tree, otherwise after
the merge window...

> ---
>  net/netfilter/ipvs/ip_vs_xmit.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
> index bf66a86..99d4a41 100644
> --- a/net/netfilter/ipvs/ip_vs_xmit.c
> +++ b/net/netfilter/ipvs/ip_vs_xmit.c
> @@ -527,6 +527,21 @@ static inline int ip_vs_tunnel_xmit_prepare(struct sk_buff *skb,
>  	return ret;
>  }
>  
> +/* In the event of a remote destination, it's possible that we would have
> + * matches against an old socket (particularly a TIME-WAIT socket). This
> + * causes havoc down the line (ip_local_out et. al. expect regular sockets
> + * and invalid memory accesses will happen) so simply drop the association
> + * in this case.
> +*/
> +static inline void ip_vs_drop_early_demux_sk(struct sk_buff *skb)
> +{
> +	/* If dev is set, the packet came from the LOCAL_IN callback and
> +	 * not from a local TCP socket.
> +	 */
> +	if (skb->dev)
> +		skb_orphan(skb);
> +}
> +
>  /* return NF_STOLEN (sent) or NF_ACCEPT if local=1 (not sent) */
>  static inline int ip_vs_nat_send_or_cont(int pf, struct sk_buff *skb,
>  					 struct ip_vs_conn *cp, int local)
> @@ -538,12 +553,21 @@ static inline int ip_vs_nat_send_or_cont(int pf, struct sk_buff *skb,
>  		ip_vs_notrack(skb);
>  	else
>  		ip_vs_update_conntrack(skb, cp, 1);
> +
> +	/* Remove the early_demux association unless it's bound for the
> +	 * exact same port and address on this host after translation.
> +	 */
> +	if (!local || cp->vport != cp->dport ||
> +	    !ip_vs_addr_equal(cp->af, &cp->vaddr, &cp->daddr))
> +		ip_vs_drop_early_demux_sk(skb);
> +
>  	if (!local) {
>  		skb_forward_csum(skb);
>  		NF_HOOK(pf, NF_INET_LOCAL_OUT, NULL, skb,
>  			NULL, skb_dst(skb)->dev, dst_output_sk);
>  	} else
>  		ret = NF_ACCEPT;
> +
>  	return ret;
>  }
>  
> @@ -557,6 +581,7 @@ static inline int ip_vs_send_or_cont(int pf, struct sk_buff *skb,
>  	if (likely(!(cp->flags & IP_VS_CONN_F_NFCT)))
>  		ip_vs_notrack(skb);
>  	if (!local) {
> +		ip_vs_drop_early_demux_sk(skb);
>  		skb_forward_csum(skb);
>  		NF_HOOK(pf, NF_INET_LOCAL_OUT, NULL, skb,
>  			NULL, skb_dst(skb)->dev, dst_output_sk);
> @@ -845,6 +870,8 @@ ip_vs_prepare_tunneled_skb(struct sk_buff *skb, int skb_af,
>  	struct ipv6hdr *old_ipv6h = NULL;
>  #endif
>  
> +	ip_vs_drop_early_demux_sk(skb);
> +
>  	if (skb_headroom(skb) < max_headroom || skb_cloned(skb)) {
>  		new_skb = skb_realloc_headroom(skb, max_headroom);
>  		if (!new_skb)
> -- 
> Alex Gartrell <agartrell@...com>

Regards

--
Julian Anastasov <ja@....bg>
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