* [PATCH 1/2] openvswitch: fix the calculation of checksum for vlan header
@ 2013-02-22 9:32 Cong Wang
2013-02-22 9:32 ` [PATCH 2/2] vlan: adjust vlan_set_encap_proto() for its callers Cong Wang
2013-02-23 1:04 ` [PATCH 1/2] openvswitch: fix the calculation of checksum for vlan header Jesse Gross
0 siblings, 2 replies; 5+ messages in thread
From: Cong Wang @ 2013-02-22 9:32 UTC (permalink / raw)
To: netdev; +Cc: David S. Miller, Jesse Gross, Cong Wang
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
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH 2/2] vlan: adjust vlan_set_encap_proto() for its callers
2013-02-22 9:32 [PATCH 1/2] openvswitch: fix the calculation of checksum for vlan header Cong Wang
@ 2013-02-22 9:32 ` Cong Wang
2013-02-23 1:05 ` Jesse Gross
2013-02-23 1:04 ` [PATCH 1/2] openvswitch: fix the calculation of checksum for vlan header Jesse Gross
1 sibling, 1 reply; 5+ messages in thread
From: Cong Wang @ 2013-02-22 9:32 UTC (permalink / raw)
To: netdev; +Cc: David S. Miller, Jesse Gross, Cong Wang
From: Cong Wang <amwang@redhat.com>
There are two places to call vlan_set_encap_proto():
vlan_untag() and __pop_vlan_tci().
vlan_untag() assumes skb->data points after mac addr, otherwise
the following code
vhdr = (struct vlan_hdr *) skb->data;
vlan_tci = ntohs(vhdr->h_vlan_TCI);
__vlan_hwaccel_put_tag(skb, vlan_tci);
skb_pull_rcsum(skb, VLAN_HLEN);
won't be correct. But __pop_vlan_tci() assumes points _before_
mac addr.
In vlan_set_encap_proto(), it looks for some magic L2 value
after mac addr:
rawp = skb->data;
if (*(unsigned short *) rawp == 0xFFFF)
...
Therefore __pop_vlan_tci() is obviously wrong.
A quick fix is avoiding using skb->data in vlan_set_encap_proto(),
use 'vhdr+1' is always correct in both cases.
Cc: David S. Miller <davem@davemloft.net>
Cc: Jesse Gross <jesse@nicira.com>
Signed-off-by: Cong Wang <amwang@redhat.com>
---
include/linux/if_vlan.h | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index d06cc5c..218a3b6 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -331,7 +331,7 @@ static inline void vlan_set_encap_proto(struct sk_buff *skb,
struct vlan_hdr *vhdr)
{
__be16 proto;
- unsigned char *rawp;
+ unsigned short *rawp;
/*
* Was a VLAN packet, grab the encapsulated protocol, which the layer
@@ -344,8 +344,8 @@ static inline void vlan_set_encap_proto(struct sk_buff *skb,
return;
}
- rawp = skb->data;
- if (*(unsigned short *) rawp == 0xFFFF)
+ rawp = (unsigned short *)(vhdr + 1);
+ if (*rawp == 0xFFFF)
/*
* This is a magic hack to spot IPX packets. Older Novell
* breaks the protocol design and runs IPX over 802.3 without
--
1.7.7.6
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 1/2] openvswitch: fix the calculation of checksum for vlan header
2013-02-22 9:32 [PATCH 1/2] openvswitch: fix the calculation of checksum for vlan header Cong Wang
2013-02-22 9:32 ` [PATCH 2/2] vlan: adjust vlan_set_encap_proto() for its callers Cong Wang
@ 2013-02-23 1:04 ` Jesse Gross
1 sibling, 0 replies; 5+ messages in thread
From: Jesse Gross @ 2013-02-23 1:04 UTC (permalink / raw)
To: Cong Wang; +Cc: netdev, David S. Miller
On Fri, Feb 22, 2013 at 1:32 AM, Cong Wang <amwang@redhat.com> wrote:
> 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>
Applied, thanks.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] vlan: adjust vlan_set_encap_proto() for its callers
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
0 siblings, 1 reply; 5+ messages in thread
From: Jesse Gross @ 2013-02-23 1:05 UTC (permalink / raw)
To: Cong Wang; +Cc: netdev, David S. Miller
On Fri, Feb 22, 2013 at 1:32 AM, Cong Wang <amwang@redhat.com> wrote:
> From: Cong Wang <amwang@redhat.com>
>
> There are two places to call vlan_set_encap_proto():
> vlan_untag() and __pop_vlan_tci().
>
> vlan_untag() assumes skb->data points after mac addr, otherwise
> the following code
>
> vhdr = (struct vlan_hdr *) skb->data;
> vlan_tci = ntohs(vhdr->h_vlan_TCI);
> __vlan_hwaccel_put_tag(skb, vlan_tci);
>
> skb_pull_rcsum(skb, VLAN_HLEN);
>
> won't be correct. But __pop_vlan_tci() assumes points _before_
> mac addr.
>
> In vlan_set_encap_proto(), it looks for some magic L2 value
> after mac addr:
>
> rawp = skb->data;
> if (*(unsigned short *) rawp == 0xFFFF)
> ...
>
> Therefore __pop_vlan_tci() is obviously wrong.
>
> A quick fix is avoiding using skb->data in vlan_set_encap_proto(),
> use 'vhdr+1' is always correct in both cases.
>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Jesse Gross <jesse@nicira.com>
> Signed-off-by: Cong Wang <amwang@redhat.com>
Acked-by: Jesse Gross <jesse@nicira.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] vlan: adjust vlan_set_encap_proto() for its callers
2013-02-23 1:05 ` Jesse Gross
@ 2013-02-24 2:01 ` David Miller
0 siblings, 0 replies; 5+ messages in thread
From: David Miller @ 2013-02-24 2:01 UTC (permalink / raw)
To: jesse; +Cc: amwang, netdev
From: Jesse Gross <jesse@nicira.com>
Date: Fri, 22 Feb 2013 17:05:01 -0800
> On Fri, Feb 22, 2013 at 1:32 AM, Cong Wang <amwang@redhat.com> wrote:
>> From: Cong Wang <amwang@redhat.com>
>>
>> There are two places to call vlan_set_encap_proto():
>> vlan_untag() and __pop_vlan_tci().
>>
>> vlan_untag() assumes skb->data points after mac addr, otherwise
>> the following code
>>
>> vhdr = (struct vlan_hdr *) skb->data;
>> vlan_tci = ntohs(vhdr->h_vlan_TCI);
>> __vlan_hwaccel_put_tag(skb, vlan_tci);
>>
>> skb_pull_rcsum(skb, VLAN_HLEN);
>>
>> won't be correct. But __pop_vlan_tci() assumes points _before_
>> mac addr.
>>
>> In vlan_set_encap_proto(), it looks for some magic L2 value
>> after mac addr:
>>
>> rawp = skb->data;
>> if (*(unsigned short *) rawp == 0xFFFF)
>> ...
>>
>> Therefore __pop_vlan_tci() is obviously wrong.
>>
>> A quick fix is avoiding using skb->data in vlan_set_encap_proto(),
>> use 'vhdr+1' is always correct in both cases.
>>
>> Cc: David S. Miller <davem@davemloft.net>
>> Cc: Jesse Gross <jesse@nicira.com>
>> Signed-off-by: Cong Wang <amwang@redhat.com>
>
> Acked-by: Jesse Gross <jesse@nicira.com>
Applied, thanks.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2013-02-24 2:01 UTC | newest]
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2013-02-22 9:32 [PATCH 1/2] openvswitch: fix the calculation of checksum for vlan header Cong Wang
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2013-02-23 1:05 ` Jesse Gross
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2013-02-23 1:04 ` [PATCH 1/2] openvswitch: fix the calculation of checksum for vlan header Jesse Gross
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