On Thu, Apr 16, 2015 at 07:40:30PM -0700, Alexei Starovoitov wrote:
> On Fri, Apr 17, 2015 at 10:15:01AM +0800, Herbert Xu wrote:
> > > seems the cleaner fix will be to push skb->mac_len instead?
> >
> > No skb->mac_len is the same as skb2->dev->hard_header_len.
>
> hmm. please help me understand the problem then.
> In the commit log you mentioned that your vlan dev and ifb
> have unequal hard header length. I think that can only happen if
> your master dev used to create vlan, didn't have vlan offload,
> so vlandev->hhl = 18 and ifb->hhl = 14. Then when tagged packet
> arrives on master device we call skb_vlan_untag() and
> skb->mac_len becomes 14, then vlan_do_receive() will do
You are right. I should've just used mac_len.
---8<---
When you redirect a VLAN device to any device, you end up with
crap in af_packet on the xmit path because hard_header_len is
not equal to skb->mac_len. So the redirected packet contains
four extra bytes at the start which then gets interpreted as
part of the MAC address.
This patch fixes this by only pushing skb->mac_len. We also
need to fix ifb because it tries to undo the pushing done by
act_mirred.
Signed-off-by: Herbert Xu <herb...@gondor.apana.org.au>
diff --git a/drivers/net/ifb.c b/drivers/net/ifb.c
index 34f846b..94570aa 100644
--- a/drivers/net/ifb.c
+++ b/drivers/net/ifb.c
@@ -105,7 +105,7 @@ static void ri_tasklet(unsigned long dev)
if (from & AT_EGRESS) {
dev_queue_xmit(skb);
} else if (from & AT_INGRESS) {
- skb_pull(skb, skb->dev->hard_header_len);
+ skb_pull(skb, skb->mac_len);
netif_receive_skb(skb);
} else
BUG();
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 5953517..3f63cea 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -157,7 +157,7 @@ static int tcf_mirred(struct sk_buff *skb, const struct
tc_action *a,
if (!(at & AT_EGRESS)) {
if (m->tcfm_ok_push)
- skb_push(skb2, skb2->dev->hard_header_len);
+ skb_push(skb2, skb->mac_len);
}
/* mirror is always swallowed */
--
Email: Herbert Xu <herb...@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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