Linux Ethernet Bridging - Apr 2007 - [Bridge] RE: [VLAN] Re: [PATCH/RFC] Let {ip, arp}tables "see" bridged VLAN tagged{I,AR}P packets

Christian Darnell wrote:
> -----Original Message-----
> 
>>From: Tommy Christensen [mailto:tommy.christensen@tpack.net]
>>Sent: Wednesday, October 08, 2003 10:09 AM
>>To: Christian Darnell
>>Cc: 'Linux 802.1Q VLAN'; Bart De Schuymer; netdev@oss.sgi.com;
bridge
>>Subject: Re: [Bridge] RE: [VLAN] Re: [PATCH/RFC] Let {ip, arp}tables
>>"see" bridged VLAN tagged{I,AR}P packets
>>
>>
>>
>>This is because the VLAN code is mangling shared data.
>>You need to do something like this:
>>
>>
>>--- linux-2.4/net/8021q/vlan_dev.c.org	2003-02-25 15:23:09.000000000
>>+0100
>>+++ linux-2.4/net/8021q/vlan_dev.c	2003-10-07 16:01:29.000000000 +0200
>>@@ -75,7 +75,12 @@
>>static inline struct sk_buff *vlan_check_reorder_header(struct sk_buff
>>*skb)
>>{
>>	if (VLAN_DEV_INFO(skb->dev)->flags & 1) {
>>-		skb = skb_share_check(skb, GFP_ATOMIC);
>>+		if (skb_shared(skb) || skb_cloned(skb)) {
>>+			struct sk_buff *nskb;
>>+			nskb = skb_copy(skb, GFP_ATOMIC);
>>+			kfree_skb(skb);
>>+			skb = nskb;
>>+		}
Thanks for catching that!

So, what good is skb_share_check then?
Maybe we should have a skb_share_or_cloned_check() ?

Ben


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

-----Original Message-----
>From: Tommy Christensen [mailto:tommy.christensen@tpack.net]
>Sent: Wednesday, October 08, 2003 10:09 AM
>To: Christian Darnell
>Cc: 'Linux 802.1Q VLAN'; Bart De Schuymer; netdev@oss.sgi.com;
bridge
>Subject: Re: [Bridge] RE: [VLAN] Re: [PATCH/RFC] Let {ip, arp}tables
>"see" bridged VLAN tagged{I,AR}P packets
>
>
>
>This is because the VLAN code is mangling shared data.
>You need to do something like this:
>
>
>--- linux-2.4/net/8021q/vlan_dev.c.org	2003-02-25 15:23:09.000000000
>+0100
>+++ linux-2.4/net/8021q/vlan_dev.c	2003-10-07 16:01:29.000000000 +0200
>@@ -75,7 +75,12 @@
> static inline struct sk_buff *vlan_check_reorder_header(struct sk_buff
>*skb)
> {
> 	if (VLAN_DEV_INFO(skb->dev)->flags & 1) {
>-		skb = skb_share_check(skb, GFP_ATOMIC);
>+		if (skb_shared(skb) || skb_cloned(skb)) {
>+			struct sk_buff *nskb;
>+			nskb = skb_copy(skb, GFP_ATOMIC);
>+			kfree_skb(skb);
>+			skb = nskb;
>+		}
> 		if (skb) {
> 			/* Lifted from Gleb's VLAN code... */
> 			memmove(skb->data - ETH_HLEN,
>
>
>Christian, could you try this out?

Thanks Tommy! I tried this (on kernel 2.4.22) and it works great!


Best Regards, 

Christian Darnell