Re: [PATCH net v2] macvtap: fix network header pointer for VLAN tagged pkts

[Toshiaki Makita]

On 15/07/21 (火) 16:18, Ivan Vecera wrote:
 Network header is set with offset ETH_HLEN but it is not true for VLAN
 (multiple-)tagged and results in checksum issues in lower devices.
 
 v2: leave skb-protocol untouched (thx Vlad), comment added
 
 Signed-off-by: Ivan Vecera ivec...@redhat.com
 ---
   drivers/net/macvtap.c | 7 +++
   1 file changed, 7 insertions(+)
 
 diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
 index 3b933bb..b75776b 100644
 --- a/drivers/net/macvtap.c
 +++ b/drivers/net/macvtap.c
 @@ -796,6 +796,13 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, 
 struct msghdr *m,
   skb_reset_mac_header(skb);
   skb-protocol = eth_hdr(skb)-h_proto;
   
 + /* Move network header to the right position for VLAN tagged packets */
 + if (skb_vlan_tagged(skb)) {

I guess you don't need the condition skb_vlan_tag_present(skb), i.e.,

if (skb-protocol == htons(ETH_P_8021Q) ||
skb-protocol == htons(ETH_P_8021AD))

 + int depth;
 + __vlan_get_protocol(skb, skb-protocol, depth);

__vlan_get_protocol() can fail, and then, depth will not be initialized.

 + skb_set_network_header(skb, depth);

I think you should set network_header after
skb_probe_transport_header(). It calls skb_flow_dissect_flow_keys(),
which seems to expect network_header to be ETH_HLEN.

Toshiaki Makita
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[PATCH net v2] macvtap: fix network header pointer for VLAN tagged pkts

[Ivan Vecera]

Network header is set with offset ETH_HLEN but it is not true for VLAN
(multiple-)tagged and results in checksum issues in lower devices.

v2: leave skb-protocol untouched (thx Vlad), comment added

Signed-off-by: Ivan Vecera ivec...@redhat.com
---
 drivers/net/macvtap.c | 7 +++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 3b933bb..b75776b 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -796,6 +796,13 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, 
struct msghdr *m,
skb_reset_mac_header(skb);
skb-protocol = eth_hdr(skb)-h_proto;
 
+   /* Move network header to the right position for VLAN tagged packets */
+   if (skb_vlan_tagged(skb)) {
+   int depth;
+   __vlan_get_protocol(skb, skb-protocol, depth);
+   skb_set_network_header(skb, depth);
+   }
+
if (vnet_hdr_len) {
err = macvtap_skb_from_vnet_hdr(q, skb, vnet_hdr);
if (err)
-- 
2.3.6

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