From: Cong Wang <amwang@redhat.com>
To: netdev@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>,
Jesse Gross <jesse@nicira.com>, Cong Wang <amwang@redhat.com>
Subject: [PATCH 1/2] openvswitch: fix the calculation of checksum for vlan header
Date: Fri, 22 Feb 2013 17:32:26 +0800 [thread overview]
Message-ID: <1361525547-21808-1-git-send-email-amwang@redhat.com> (raw)
From: Cong Wang <amwang@redhat.com>
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>
---
net/openvswitch/actions.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index ac2defe..d4d5363 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);
--
1.7.7.6
next reply other threads:[~2013-02-22 9:32 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-22 9:32 Cong Wang [this message]
2013-02-22 9:32 ` [PATCH 2/2] vlan: adjust vlan_set_encap_proto() for its callers Cong Wang
2013-02-23 1:05 ` Jesse Gross
2013-02-24 2:01 ` David Miller
2013-02-23 1:04 ` [PATCH 1/2] openvswitch: fix the calculation of checksum for vlan header Jesse Gross
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1361525547-21808-1-git-send-email-amwang@redhat.com \
--to=amwang@redhat.com \
--cc=davem@davemloft.net \
--cc=jesse@nicira.com \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).