[PATCH v2] ipt_REJECT: can't work with bridges

[PATCH v2] ipt_REJECT: can't work with bridges

[Changli Gao]

ipt_REJECT: can't work with bridges

ip_route_me_harder can't create the route cache when the outdev is the same with
the indev for the skbs whichout a valid protocol set.

__mkroute_input functions has this check:
1998         if (skb->protocol != htons(ETH_P_IP)) {
1999                 /* Not IP (i.e. ARP). Do not create route, if it is
2000                  * invalid for proxy arp. DNAT routes are always valid.
2001                  *
2002                  * Proxy arp feature have been extended to allow, ARP
2003                  * replies back to the same interface, to support
2004                  * Private VLAN switch technologies. See arp.c.
2005                  */
2006                 if (out_dev == in_dev &&
2007                     IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
2008                         err = -EINVAL;
2009                         goto cleanup;
2010                 }
2011         }

This patch gives the new skb a valid protocol to bypass this check. In order to
make ipt_REJECT work with bridges, you also need to enable ip_forward.

This patch also fixes a regression. When we used skb_copy_expand(), we didn't
have this issue stated above, as the protocol was properly set. In fact, the
regression also affects TC classification and packet sockets.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
----
 net/ipv4/netfilter/ipt_REJECT.c |    1 +
 1 file changed, 1 insertion(+)
diff --git a/net/ipv4/netfilter/ipt_REJECT.c b/net/ipv4/netfilter/ipt_REJECT.c
index bbbd273..60b8832 100644
--- a/net/ipv4/netfilter/ipt_REJECT.c
+++ b/net/ipv4/netfilter/ipt_REJECT.c
@@ -111,6 +111,7 @@ static void send_reset(struct sk_buff *oldskb, int hook)
 	/* ip_route_me_harder expects skb->dst to be set */
 	skb_dst_set_noref(nskb, skb_dst(oldskb));
 
+	nskb->protocol = htons(ETH_P_IP);
 	if (ip_route_me_harder(nskb, addr_type))
 		goto free_nskb;
 

Re: [PATCH v2] ipt_REJECT: can't work with bridges

[Changli Gao]

On Mon, Jul 5, 2010 at 3:16 PM, Changli Gao <xiaosuo@gmail.com> wrote:
> ipt_REJECT: can't work with bridges
>
> ip_route_me_harder can't create the route cache when the outdev is the same with
> the indev for the skbs whichout a valid protocol set.
>
> __mkroute_input functions has this check:
> 1998         if (skb->protocol != htons(ETH_P_IP)) {
> 1999                 /* Not IP (i.e. ARP). Do not create route, if it is
> 2000                  * invalid for proxy arp. DNAT routes are always valid.
> 2001                  *
> 2002                  * Proxy arp feature have been extended to allow, ARP
> 2003                  * replies back to the same interface, to support
> 2004                  * Private VLAN switch technologies. See arp.c.
> 2005                  */
> 2006                 if (out_dev == in_dev &&
> 2007                     IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
> 2008                         err = -EINVAL;
> 2009                         goto cleanup;
> 2010                 }
> 2011         }
>
> This patch gives the new skb a valid protocol to bypass this check. In order to
> make ipt_REJECT work with bridges, you also need to enable ip_forward.
>
> This patch also fixes a regression. When we used skb_copy_expand(), we didn't
> have this issue stated above, as the protocol was properly set. In fact, the
> regression also affects TC classification and packet sockets.
>
> Signed-off-by: Changli Gao <xiaosuo@gmail.com>
> ----
>  net/ipv4/netfilter/ipt_REJECT.c |    1 +
>  1 file changed, 1 insertion(+)
> diff --git a/net/ipv4/netfilter/ipt_REJECT.c b/net/ipv4/netfilter/ipt_REJECT.c
> index bbbd273..60b8832 100644
> --- a/net/ipv4/netfilter/ipt_REJECT.c
> +++ b/net/ipv4/netfilter/ipt_REJECT.c
> @@ -111,6 +111,7 @@ static void send_reset(struct sk_buff *oldskb, int hook)
>        /* ip_route_me_harder expects skb->dst to be set */
>        skb_dst_set_noref(nskb, skb_dst(oldskb));
>
> +       nskb->protocol = htons(ETH_P_IP);
>        if (ip_route_me_harder(nskb, addr_type))
>                goto free_nskb;
>
>

This bugfix patch seems missed, or I need to respin it? Thanks.

-- 
Regards,
Changli Gao(xiaosuo@gmail.com)
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