On Thu, Jan 17, 2019 at 12:59 AM Toshiaki Makita <makita.toshiaki@xxxxxxxxxxxxx> wrote: > > On 2019/01/17 17:17, Zahari Doychev wrote: > > On Tue, Jan 15, 2019 at 03:11:28PM +0900, Toshiaki Makita wrote: > >> On 2019/01/13 22:59, Zahari Doychev wrote: > >>> Use the skb->mac_len instead of using the ETH_HLEN when pushing the skb > >>> data pointer. This fixes sending incorrect packets when more than one > >>> vlan tags are pushed by tc-vlan and the mac header length is bigger than > >>> ETH_HLEN. In this way the vlan tagged contained in the skb is inserted at > >>> right offset in the packet payload before sending the packet. > >>> > >>> Signed-off-by: Zahari Doychev <zahari.doychev@xxxxxxxxx> > >>> --- > >>> net/bridge/br_forward.c | 2 +- > >>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>> > >>> diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c > >>> index 5372e2042adf..55f928043f77 100644 > >>> --- a/net/bridge/br_forward.c > >>> +++ b/net/bridge/br_forward.c > >>> @@ -39,7 +39,7 @@ int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb > >>> if (!is_skb_forwardable(skb->dev, skb)) > >>> goto drop; > >>> > >>> - skb_push(skb, ETH_HLEN); > >>> + skb_push(skb, skb->mac_len); > >>> br_drop_fake_rtable(skb); > >>> > >>> if (skb->ip_summed == CHECKSUM_PARTIAL && > >>> > >> > >> I guess you mean skb->data points to mac_header + ETH_HLEN + VLAN_HLEN > >> when bridge receives skbs in br_handle_frame()? > > > > yes, this is what I see. > > > >> If so, the behavior of act_vlan is odd. Normal double tagged skbs from > >> hardware devices should have skb->data pointing to mac_header + ETH_HLEN > >> because they just call eth_type_trans() before entering > >> netif_receive_skb()... > >> I think act_vlan needs some fix. > > > > The act_valn is using the skb_vlan_push(...) to add the vlan tags and in this > > way increasing the skb->data and mac_len. So I think I can add a fix there to > > set the skb->data to point to mac_header + ETH_HLEN when more tags are added. > > As skb->data always points to mac_header after calling skb_vlan_push(), > we probably need to remember mac_len before invocation of it? > > The problem should be this part in tcf_vlan_act(): > > > out: > > if (skb_at_tc_ingress(skb)) > > skb_pull_rcsum(skb, skb->mac_len); > > skb->mac_len should not be used here. I am confused. This code is to push skb->data back to network header. If skb_vlan_push() pushes skb->data to mac header, then this code is correct for pulling it back to network header, as skb->mac_len is updated accordingly inside skb_vlan_push() too. What goes wrong here? skb->mac_len isn't correct for double tagging? Thanks.
