Re: [PATCH net] net: avoid vlan ptype specific match to be leaked on real device

Jiri Pirko
2016-06-22T12:01:00Z

Wed, Jun 22, 2016 at 12:25:15PM CEST, pabeni@redhat.com wrote:
>Before the commit 0dfe17823945 ("net: vlan: goto another_round
>instead of calling __netif_receive_skb"), on tagged skb ingress,
>ptype specific protocol matches were delivered only to the
>related vlan device, if any.
>After said commit, jumping back to the 'another_round' label, allows
>the later ptype specific check to match both orig_dev and skb->dev,
>delivering the skb to both the vlan device and the underlying
>device.
>This cause i.e. packet sockets bound to a specific protocol type on
>one of said devices to receive also frames really targeting the
>other device.
>This commit resets orig_dev before performing another round due to
>vlan processing, allowing the skb to be delivered once again only
>to the vlan specific ptypes.

I don't get why vlan should behave differently in this comparing to
other stacked devices like bond/team/br etc.

Could you please explain?

>
>Fixes: 0dfe17823945 ("net: vlan: goto another_round instead of calling __netif_receive_skb")
>Reported-by: Ryan Liu <Ryan.Liu@alcatel-lucent.com>
>Reported-by: Cliff Chen <Cliff.Chen@alcatel-lucent.com>
>Signed-off-by: Paolo Abeni <pabeni@redhat.com>
>---
> net/core/dev.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
>diff --git a/net/core/dev.c b/net/core/dev.c
>index 904ff43..9d08dd6 100644
>--- a/net/core/dev.c
>+++ b/net/core/dev.c
>@@ -4144,10 +4144,15 @@ ncls:
> ret = deliver_skb(skb, pt_prev, orig_dev);
> pt_prev = NULL;
> }
>- if (vlan_do_receive(&skb))
>+ if (vlan_do_receive(&skb)) {
>+ /* avoid delivering to ptype registered on
>+ * vlan's underlying device only
>+ */
>+ orig_dev = skb->dev;
> goto another_round;
>- else if (unlikely(!skb))
>+ } else if (unlikely(!skb)) {
> goto out;
>+ }
> }
>
> rx_handler = rcu_dereference(skb->dev->rx_handler);
>--
>1.8.3.1
>