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authorCong Wang <amwang@redhat.com>2013-02-22 17:32:26 +0800
committerJesse Gross <jesse@nicira.com>2013-02-22 17:02:38 -0800
commit7b024082b2b279af58e24ebd46e81777723d58da (patch)
treebea9b80e2869695f4da100df6c0b3731bd02fe1e /net/openvswitch
parent17b682a04841233f827073b327c6533e478dfcd4 (diff)
downloadlinux-7b024082b2b279af58e24ebd46e81777723d58da.tar.gz
openvswitch: fix the calculation of checksum for vlan header
In vlan_insert_tag(), we insert a 4-byte VLAN header _after_ mac header: memmove(skb->data, skb->data + VLAN_HLEN, 2 * ETH_ALEN); ... veth->h_vlan_proto = htons(ETH_P_8021Q); ... veth->h_vlan_TCI = htons(vlan_tci); so after it, we should recompute the checksum to include these 4 bytes. skb->data still points to the mac header, therefore VLAN header is at (2 * ETH_ALEN = 12) bytes after it, not (ETH_HLEN = 14) bytes. This can also be observed via tcpdump: 0x0000: ffff ffff ffff 5254 005d 6f6e 8100 000a 0x0010: 0806 0001 0800 0604 0001 5254 005d 6f6e 0x0020: c0a8 026e 0000 0000 0000 c0a8 0282 Similar for __pop_vlan_tci(), the vlan header we remove is the one overwritten in: memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN); Therefore the VLAN_HLEN = 4 bytes after 2 * ETH_ALEN is the part we want to sub from checksum. Cc: David S. Miller <davem@davemloft.net> Cc: Jesse Gross <jesse@nicira.com> Signed-off-by: Cong Wang <amwang@redhat.com> Signed-off-by: Jesse Gross <jesse@nicira.com>
Diffstat (limited to 'net/openvswitch')
-rw-r--r--net/openvswitch/actions.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index ac2defeeba8..d4d5363c7ba 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -58,7 +58,7 @@ static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci)
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->csum = csum_sub(skb->csum, csum_partial(skb->data
- + ETH_HLEN, VLAN_HLEN, 0));
+ + (2 * ETH_ALEN), VLAN_HLEN, 0));
vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
*current_tci = vhdr->h_vlan_TCI;
@@ -115,7 +115,7 @@ static int push_vlan(struct sk_buff *skb, const struct ovs_action_push_vlan *vla
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->csum = csum_add(skb->csum, csum_partial(skb->data
- + ETH_HLEN, VLAN_HLEN, 0));
+ + (2 * ETH_ALEN), VLAN_HLEN, 0));
}
__vlan_hwaccel_put_tag(skb, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);