net: Fix some corner cases in dev_can_checksum()
dev_can_checksum() incorrectly returns true in these cases:
1. The skb has both out-of-band and in-band VLAN tags and the device
supports checksum offload for the encapsulated protocol but only with
one layer of encapsulation.
2. The skb has a VLAN tag and the device supports generic checksumming
but not in conjunction with VLAN encapsulation.
Rearrange the VLAN tag checks to avoid these.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index e8a8dc1..3c5fbfb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1696,22 +1696,18 @@
static bool dev_can_checksum(struct net_device *dev, struct sk_buff *skb)
{
+ __be16 protocol = skb->protocol;
int features = dev->features;
- if (vlan_tx_tag_present(skb))
+ if (vlan_tx_tag_present(skb)) {
features &= dev->vlan_features;
-
- if (can_checksum_protocol(features, skb->protocol))
- return true;
-
- if (skb->protocol == htons(ETH_P_8021Q)) {
+ } else if (protocol == htons(ETH_P_8021Q)) {
struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
- if (can_checksum_protocol(dev->features & dev->vlan_features,
- veh->h_vlan_encapsulated_proto))
- return true;
+ protocol = veh->h_vlan_encapsulated_proto;
+ features &= dev->vlan_features;
}
- return false;
+ return can_checksum_protocol(features, protocol);
}
/**