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Message-Id: <0cd1047a2432736459fabbe97a8fb81c449fd827.1372232028.git.yamahata@valinux.co.jp>
Date: Wed, 26 Jun 2013 16:34:52 +0900
From: Isaku Yamahata <yamahata@...inux.co.jp>
To: netdev@...r.kernel.org
Cc: yamahata@...inux.co.jp, murphy.mccauley@...il.com,
Pravin B Shelar <pshelar@...ira.com>,
Jesse Gross <jesse@...ira.com>, dev@...nvswitch.org
Subject: [PATCH] loopback: set pkt_type to PACKET_HOST explicitly
Reset pkt_type to PACKET_HOST when loopback device receives packet
before calling eth_type_trans()
ip-encapsulated packets can be handled by localhost. But skb->pkt_type
can be PACKET_OTHERHOST when packet comes into ip tunnel device. In that case,
the packet is dropped by ip_rcv() because loopback_xmit() doesn't set
skb->pkt_type to PACKET_HOST.
netns A | root netns | netns B
veth<->veth=bridge=gretap <-loop back-> gretap=bridge=veth<->veth
arp packet ->
pkt_type
BROADCAST----loopback_xmit()-->ip_rcv()------------------->
<- arp reply
pkt_type
ip_rcv()<---loopback_xmit()-----OTHERHOST
drop
sample operations
ip link add tapa type gretap remote 172.17.107.4 local 172.17.107.3
ip link add tapb type gretap remote 172.17.107.3 local 172.17.107.4
ip link set tapa up
ip link set tapb up
ip address add 172.17.107.3 dev tapa
ip address add 172.17.107.4 dev tapb
ip route get 172.17.107.3
> local 172.17.107.3 dev lo src 172.17.107.3
> cache <local>
ip route get 172.17.107.4
> local 172.17.107.4 dev lo src 172.17.107.4
> cache <local>
ip link add vetha type veth peer name vetha-peer
ip link add vethb type veth peer name vethb-peer
brctl addbr bra
brctl addbr brb
brctl addif bra tapa
brctl addif bra vetha-peer
brctl addif brb tapb
brctl addif brb vethb-peer
brctl show
> bridge name bridge id STP enabled interfaces
> bra 8000.6ea21e758ff1 no tapa
> vetha-peer
> brb 8000.420020eb92d5 no tapb
> vethb-peer
ip link set vetha-peer up
ip link set vethb-peer up
ip link set bra up
ip link set brb up
ip netns add a
ip netns add b
ip link set vetha netns a
ip link set vethb netns b
ip netns exec a ip address add 10.0.0.3/24 dev vetha
ip netns exec b ip address add 10.0.0.4/24 dev vethb
ip netns exec a ip link set vetha up
ip netns exec b ip link set vethb up
ip netns exec a arping -I vetha 10.0.0.4
ARPING 10.0.0.4 from 10.0.0.3 vetha
^CSent 2 probes (2 broadcast(s))
Received 0 response(s)
Cc: Pravin B Shelar <pshelar@...ira.com>
Cc: Jesse Gross <jesse@...ira.com>
Cc: dev@...nvswitch.org
Signed-off-by: Isaku Yamahata <yamahata@...inux.co.jp>
---
drivers/net/loopback.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index fcbf680..2694638 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -82,6 +82,12 @@ static netdev_tx_t loopback_xmit(struct sk_buff *skb,
*/
skb_dst_force(skb);
+ /* pkt_type is not always PACKET_HOST because
+ * this skb comes from other components.
+ * Since eth_type_trans() sets pkt_type _except_ PACKET_HOST case,
+ * set it explicitly.
+ */
+ skb->pkt_type = PACKET_HOST;
skb->protocol = eth_type_trans(skb, dev);
/* it's OK to use per_cpu_ptr() because BHs are off */
--
1.7.10.4
--
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