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Allow fragmentation of VLAN packets traversing a bridge.

PATCH In review Saikiran Madugula 2 participants 6 messages Apr 17, 2009 – Apr 20, 2009

Subsystems (4)
Networking Network drivers netfilter Ethernet bridge
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Saikiran Madugula

author
#0 lore raw

PATCH 1/1 Allow fragmentation of VLAN packets traversing a bridge.

br_nf_dev_queue_xmit only checks for ETH_P_IP packets for fragmenting but not VLAN packets. This results in dropping of large VLAN packets. This can be observed when connection tracking is enabled. Connection tracking re-assembles fragmented packets, and these have to be re-fragmented when transmitting out.

Signed-off-by Saikiran Madugula <[email protected]>
---
 net/bridge/br_netfilter.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
net/bridge/br_netfilter.c +1 -1
index 3953ac4..941f702 100644
@@ -790,7 +790,7 @@ static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb,
 
 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 {
-	if (skb->protocol == htons(ETH_P_IP) &&
+	if ((skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb)) &&
 	    skb->len > skb->dev->mtu &&
 	    !skb_is_gso(skb))
 		return ip_fragment(skb, br_dev_queue_push_xmit);
Signature · 1 line
1.5.6.3
#1 lore raw
Quoted 15 lines · Saikiran Madugula

br_nf_dev_queue_xmit only checks for ETH_P_IP packets for fragmenting but not VLAN packets. This results in dropping of large VLAN packets. This can be observed when connection tracking is enabled. Connection tracking re-assembles fragmented packets, and these have to be re-fragmented when transmitting out.

Signed-off-by Saikiran Madugula <[email protected]>
---
 net/bridge/br_netfilter.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
net/bridge/br_netfilter.c +0 -0
index 3953ac4..941f702 100644

net/bridge/br_netfilter.c static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb, · line 796

Quoted 8 lines
net/bridge/br_netfilter.c +1 -1
@@ -790,7 +790,7 @@ static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb,
 
 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 {
-	if (skb->protocol == htons(ETH_P_IP) &&
+	if ((skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb)) &&
 	    skb->len > skb->dev->mtu &&
 	    !skb_is_gso(skb))
 		return ip_fragment(skb, br_dev_queue_push_xmit);

Please add an additional check for skb->nfct != NULL to make sure that this only refragments packets defragmented by conntrack.

author
#2 lore raw
Quoted 21 lines · Patrick McHardy
Quoted 20 lines · Saikiran Madugula

br_nf_dev_queue_xmit only checks for ETH_P_IP packets for fragmenting but not
VLAN packets. This results in dropping of large VLAN packets. This can be observed when connection tracking is enabled. Connection tracking re-assembles
fragmented packets, and these have to be re-fragmented when transmitting out.

Signed-off-by Saikiran Madugula <[email protected]>
---
 net/bridge/br_netfilter.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
net/bridge/br_netfilter.c +0 -0
index 3953ac4..941f702 100644
@@ -790,7 +790,7 @@ static unsigned int br_nf_local_out(unsigned int
 hook, struct sk_buff *skb,
Quoted 10 lines
Quoted 7 lines
net/bridge/br_netfilter.c +1 -1
 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 {
-    if (skb->protocol == htons(ETH_P_IP) &&
+    if ((skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb)) &&
         skb->len > skb->dev->mtu &&
         !skb_is_gso(skb))

         return ip_fragment(skb, br_dev_queue_push_xmit);

Please add an additional check for skb->nfct != NULL to make sure that this only refragments packets defragmented by conntrack.

Thanks for the feedback, skb->nfct is present only if CONFIG_NF_CONNTRACK or CONFIG_NF_CONNTRACK_MODULE is defined. Was wondering if the entire check before ip_fragment is necessary if NF_CONNTRACK is not defined. If not, I will post updated patch as per your suggestion.

#3 lore raw
Quoted 6 lines · Saikiran Madugula
Quoted 5 lines · Patrick McHardy
Quoted 5 lines
net/bridge/br_netfilter.c +1 -1
-    if (skb->protocol == htons(ETH_P_IP) &&
+    if ((skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb)) &&
         skb->len > skb->dev->mtu &&
         !skb_is_gso(skb))
         return ip_fragment(skb, br_dev_queue_push_xmit);
Quoted 7 lines
Quoted 2 lines

Please add an additional check for skb->nfct != NULL to make sure that this only refragments packets defragmented by conntrack.

Thanks for the feedback, skb->nfct is present only if CONFIG_NF_CONNTRACK or CONFIG_NF_CONNTRACK_MODULE is defined. Was wondering if the entire check before ip_fragment is necessary if NF_CONNTRACK is not defined. If not, I will post updated patch as per your suggestion.

Good point. Yes, everything related to fragmenting is only needed with NF_CONNTRACK, so an additional ifdef makes sense.

author
#4 lore raw

PATCH 1/1 Allow fragmentation of VLAN packets traversing a bridge.

br_nf_dev_queue_xmit only checks for ETH_P_IP packets for fragmenting but not VLAN packets. This results in dropping of large VLAN packets. This can be observed when connection tracking is enabled. Connection tracking re-assembles fragmented packets, and these have to re-fragmented when transmitting out. Also, make sure only refragmented packets are defragmented as per suggestion from Patrick McHardy.

Signed-off-by Saikiran Madugula <[email protected]>
---
 net/bridge/br_netfilter.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)
net/bridge/br_netfilter.c +9 -1
index 3953ac4..e4a418f 100644
@@ -788,15 +788,23 @@ static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb,
 	return NF_STOLEN;
 }
 
+#if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)
 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 {
-	if (skb->protocol == htons(ETH_P_IP) &&
+	if (skb->nfct != NULL &&
+	    (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb)) &&
 	    skb->len > skb->dev->mtu &&
 	    !skb_is_gso(skb))
 		return ip_fragment(skb, br_dev_queue_push_xmit);
 	else
 		return br_dev_queue_push_xmit(skb);
 }
+#else
+static int br_nf_dev_queue_xmit(struct sk_buff *skb)
+{
+        return br_dev_queue_push_xmit(skb);
+}
+#endif
 
 /* PF_BRIDGE/POST_ROUTING ********************************************/
 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
Signature · 1 line
1.5.6.3
Applied
#5 lore raw
Quoted 6 lines · Saikiran Madugula

br_nf_dev_queue_xmit only checks for ETH_P_IP packets for fragmenting but not VLAN packets. This results in dropping of large VLAN packets. This can be observed when connection tracking is enabled. Connection tracking re-assembles fragmented packets, and these have to re-fragmented when transmitting out. Also, make sure only refragmented packets are defragmented as per suggestion from Patrick McHardy.

Applied, thanks Saikiran.