[net-next,4/5] netback: set transport header before passing it to kernel
diff mbox series

Message ID 1364278799-37285-5-git-send-email-jasowang@redhat.com
State New, archived
Headers show
Series
  • set transport header for untrusted packets
Related show

Commit Message

Jason Wang March 26, 2013, 6:19 a.m. UTC
Currently, for the packets receives from netback, before doing header check,
kernel just reset the transport header in netif_receive_skb() which pretends non
l4 header. This is suboptimal for precise packet length estimation (introduced
in 1def9238: net_sched: more precise pkt_len computation) which needs correct l4
header for gso packets.

The patch just reuse the header probed by netback for partial checksum packets
and tries to use skb_flow_dissect() for other cases, if both fail, just pretend
no l4 header.

Cc: Eric Dumazet <edumazet@google.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/xen-netback/netback.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

Comments

Ian Campbell April 10, 2013, 1:33 p.m. UTC | #1
On Tue, 2013-03-26 at 06:19 +0000, Jason Wang wrote:
> Currently, for the packets receives from netback, before doing header check,
> kernel just reset the transport header in netif_receive_skb() which pretends non
> l4 header. This is suboptimal for precise packet length estimation (introduced
> in 1def9238: net_sched: more precise pkt_len computation) which needs correct l4
> header for gso packets.
> 
> The patch just reuse the header probed by netback for partial checksum packets
> and tries to use skb_flow_dissect() for other cases, if both fail, just pretend
> no l4 header.
> 
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Ian Campbell <ian.campbell@citrix.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  drivers/net/xen-netback/netback.c |   12 ++++++++++++
>  1 files changed, 12 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
> index aa28550..fc8faa7 100644
> --- a/drivers/net/xen-netback/netback.c
> +++ b/drivers/net/xen-netback/netback.c
> @@ -39,6 +39,7 @@
>  #include <linux/udp.h>
>  
>  #include <net/tcp.h>
> +#include <net/flow_keys.h>
>  
>  #include <xen/xen.h>
>  #include <xen/events.h>
> @@ -1184,6 +1185,7 @@ static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
>  	if (th >= skb_tail_pointer(skb))
>  		goto out;
>  
> +	skb_set_transport_header(skb, 4 * iph->ihl);
>  	skb->csum_start = th - skb->head;

Should the use of th here (and perhaps above) be replaced with
skb_transport_header() too?

>  	switch (iph->protocol) {
>  	case IPPROTO_TCP:
> @@ -1495,6 +1497,7 @@ static void xen_netbk_tx_submit(struct xen_netbk *netbk)
>  
>  		skb->dev      = vif->dev;
>  		skb->protocol = eth_type_trans(skb, skb->dev);
> +		skb_reset_network_header(skb);
>  
>  		if (checksum_setup(vif, skb)) {
>  			netdev_dbg(vif->dev,
> @@ -1503,6 +1506,15 @@ static void xen_netbk_tx_submit(struct xen_netbk *netbk)
>  			continue;
>  		}
>  
> +		if (!skb_transport_header_was_set(skb)) {
> +			struct flow_keys keys;
> +
> +			if (skb_flow_dissect(skb, &keys))
> +				skb_set_transport_header(skb, keys.thoff);
> +			else
> +				skb_reset_transport_header(skb);
> +		}
> +
>  		vif->dev->stats.rx_bytes += skb->len;
>  		vif->dev->stats.rx_packets++;
>  


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Jason Wang April 11, 2013, 6:37 a.m. UTC | #2
On 04/10/2013 09:33 PM, Ian Campbell wrote:
> On Tue, 2013-03-26 at 06:19 +0000, Jason Wang wrote:
>> Currently, for the packets receives from netback, before doing header check,
>> kernel just reset the transport header in netif_receive_skb() which pretends non
>> l4 header. This is suboptimal for precise packet length estimation (introduced
>> in 1def9238: net_sched: more precise pkt_len computation) which needs correct l4
>> header for gso packets.
>>
>> The patch just reuse the header probed by netback for partial checksum packets
>> and tries to use skb_flow_dissect() for other cases, if both fail, just pretend
>> no l4 header.
>>
>> Cc: Eric Dumazet <edumazet@google.com>
>> Cc: Ian Campbell <ian.campbell@citrix.com>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>>  drivers/net/xen-netback/netback.c |   12 ++++++++++++
>>  1 files changed, 12 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
>> index aa28550..fc8faa7 100644
>> --- a/drivers/net/xen-netback/netback.c
>> +++ b/drivers/net/xen-netback/netback.c
>> @@ -39,6 +39,7 @@
>>  #include <linux/udp.h>
>>  
>>  #include <net/tcp.h>
>> +#include <net/flow_keys.h>
>>  
>>  #include <xen/xen.h>
>>  #include <xen/events.h>
>> @@ -1184,6 +1185,7 @@ static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
>>  	if (th >= skb_tail_pointer(skb))
>>  		goto out;
>>  
>> +	skb_set_transport_header(skb, 4 * iph->ihl);
>>  	skb->csum_start = th - skb->head;
> Should the use of th here (and perhaps above) be replaced with
> skb_transport_header() too?

Yes, and furthermore looks like we can use skb_partial_csum_set() here,
will send a patch.

Thanks
>>  	switch (iph->protocol) {
>>  	case IPPROTO_TCP:
>> @@ -1495,6 +1497,7 @@ static void xen_netbk_tx_submit(struct xen_netbk *netbk)
>>  
>>  		skb->dev      = vif->dev;
>>  		skb->protocol = eth_type_trans(skb, skb->dev);
>> +		skb_reset_network_header(skb);
>>  
>>  		if (checksum_setup(vif, skb)) {
>>  			netdev_dbg(vif->dev,
>> @@ -1503,6 +1506,15 @@ static void xen_netbk_tx_submit(struct xen_netbk *netbk)
>>  			continue;
>>  		}
>>  
>> +		if (!skb_transport_header_was_set(skb)) {
>> +			struct flow_keys keys;
>> +
>> +			if (skb_flow_dissect(skb, &keys))
>> +				skb_set_transport_header(skb, keys.thoff);
>> +			else
>> +				skb_reset_transport_header(skb);
>> +		}
>> +
>>  		vif->dev->stats.rx_bytes += skb->len;
>>  		vif->dev->stats.rx_packets++;
>>  
>
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Patch
diff mbox series

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index aa28550..fc8faa7 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -39,6 +39,7 @@ 
 #include <linux/udp.h>
 
 #include <net/tcp.h>
+#include <net/flow_keys.h>
 
 #include <xen/xen.h>
 #include <xen/events.h>
@@ -1184,6 +1185,7 @@  static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
 	if (th >= skb_tail_pointer(skb))
 		goto out;
 
+	skb_set_transport_header(skb, 4 * iph->ihl);
 	skb->csum_start = th - skb->head;
 	switch (iph->protocol) {
 	case IPPROTO_TCP:
@@ -1495,6 +1497,7 @@  static void xen_netbk_tx_submit(struct xen_netbk *netbk)
 
 		skb->dev      = vif->dev;
 		skb->protocol = eth_type_trans(skb, skb->dev);
+		skb_reset_network_header(skb);
 
 		if (checksum_setup(vif, skb)) {
 			netdev_dbg(vif->dev,
@@ -1503,6 +1506,15 @@  static void xen_netbk_tx_submit(struct xen_netbk *netbk)
 			continue;
 		}
 
+		if (!skb_transport_header_was_set(skb)) {
+			struct flow_keys keys;
+
+			if (skb_flow_dissect(skb, &keys))
+				skb_set_transport_header(skb, keys.thoff);
+			else
+				skb_reset_transport_header(skb);
+		}
+
 		vif->dev->stats.rx_bytes += skb->len;
 		vif->dev->stats.rx_packets++;