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* [PATCH 0/1] Issue description and debug
@ 2023-10-08  0:59 Heng Guo
  2023-10-08  0:59 ` [PATCH 1/1] net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check Heng Guo
  0 siblings, 1 reply; 6+ messages in thread
From: Heng Guo @ 2023-10-08  0:59 UTC (permalink / raw)
  To: davem, dsahern, edumazet, kuba, pabeni; +Cc: netdev, filip.pudak, heng.guo

Hi maintainers,

The IPSTATS_MIB_OUTFORWDATAGRAMS is counted after fragment check.

Reproduce environment:
network with 3 VM linuxs is connected as below:
VM1<---->VM2(latest kernel 6.5.0-rc7)<---->VM3
VM1: eth0 ip: 192.168.122.207 MTU 1800
VM2: eth0 ip: 192.168.122.208, eth1 ip: 192.168.123.224 MTU 1500
VM3: eth0 ip: 192.168.123.240 MTU 1800

Reproduce:
VM1 send 1600 bytes UDP data to VM3 using tools scapy with flags='DF'.
scapy command:
send(IP(dst="192.168.123.240",flags='DF')/UDP()/str('0'*1600),count=1,
inter=1.000000)

Result:
Before IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
OutDiscards OutNoRoutes ReasmTimeout ReasmReqdss
Ip: 1 64 6 0 2 2 0 0 2 4 0 0 0 0 0 0 0 0 0
......
root@qemux86-64:~#
----------------------------------------------------------------------
After IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
OutDiscards OutNoRoutes ReasmTimeout ReasmReqdss
Ip: 1 64 7 0 2 2 0 0 2 5 0 0 0 0 0 0 0 1 0
......
root@qemux86-64:~#
----------------------------------------------------------------------
ForwDatagrams is always keeping 2 without increment.

Issue description and patch:
ip_exceeds_mtu() in ip_forward() drops this IP datagram because skb len
(1600 sending by scapy) is over MTU(1500 in VM2) and "DF" is set.
According to RFC 4293 "3.2.3. IP Statistics Tables",
  +-------+------>------+----->-----+----->-----+
  | InForwDatagrams (6) | OutForwDatagrams (6)  |
  |                     V                       +->-+ OutFragReqds
  |                 InNoRoutes                  |   | (packets)
  / (local packet (3)                           |   |
  |  IF is that of the address                  |   +--> OutFragFails
  |  and may not be the receiving IF)           |   |    (packets)
the IPSTATS_MIB_OUTFORWDATAGRAMS should be counted before fragment
check.
The existing implementation, instead, would incease the counter after
fragment check: ip_exceeds_mtu() in ipv4 and ip6_pkt_too_big() in ipv6.
So do patch to move IPSTATS_MIB_OUTFORWDATAGRAMS counter to ip_forward()
for ipv4 and ip6_forward() for ipv6.

Test result with patch:
Before IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
 ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
 OutDiscards OutNoRoutes ReasmTimeout ReasmReqdss
Ip: 1 64 6 0 2 2 0 0 2 4 0 0 0 0 0 0 0 0 0
......
root@qemux86-64:~#
----------------------------------------------------------------------
After IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
 ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
 OutDiscards OutNoRoutes ReasmTimeout ReasmReqdss
Ip: 1 64 7 0 2 3 0 0 2 5 0 0 0 0 0 0 0 1 0
......
root@qemux86-64:~#
----------------------------------------------------------------------
ForwDatagrams is updated from 2 to 3.

Thanks,
Heng

This is a new email thread, last one is:
https://lore.kernel.org/all/20230914051623.2180843-2-heng.guo@windriver.com


Heng Guo (1):
  net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment
    check

 net/ipv4/ip_forward.c | 4 ++--
 net/ipv6/ip6_output.c | 6 ++----
 2 files changed, 4 insertions(+), 6 deletions(-)

-- 
2.25.1


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH 1/1] net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check
  2023-10-08  0:59 [PATCH 0/1] Issue description and debug Heng Guo
@ 2023-10-08  0:59 ` Heng Guo
  2023-10-10 16:26   ` David Ahern
  2023-10-11  1:51   ` [PATCH] " Heng Guo
  0 siblings, 2 replies; 6+ messages in thread
From: Heng Guo @ 2023-10-08  0:59 UTC (permalink / raw)
  To: davem, dsahern, edumazet, kuba, pabeni; +Cc: netdev, filip.pudak, heng.guo

According to RFC 4293 "3.2.3. IP Statistics Tables",
  +-------+------>------+----->-----+----->-----+
  | InForwDatagrams (6) | OutForwDatagrams (6)  |
  |                     V                       +->-+ OutFragReqds
  |                 InNoRoutes                  |   | (packets)
  / (local packet (3)                           |   |
  |  IF is that of the address                  |   +--> OutFragFails
  |  and may not be the receiving IF)           |   |    (packets)
the IPSTATS_MIB_OUTFORWDATAGRAMS should be counted before fragment
check.

The existing implementation, instead, would incease the counter after
fragment check: ip_exceeds_mtu() in ipv4 and ip6_pkt_too_big() in ipv6.

So move IPSTATS_MIB_OUTFORWDATAGRAMS counter to ip_forward() for ipv4 and
ip6_forward() for ipv6.

Reviewed-by: Filip Pudak <filip.pudak@windriver.com>
Signed-off-by: Heng Guo <heng.guo@windriver.com>
---
 net/ipv4/ip_forward.c | 4 ++--
 net/ipv6/ip6_output.c | 6 ++----
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
index 66fac1216d46..8b65f12583eb 100644
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -66,8 +66,6 @@ static int ip_forward_finish(struct net *net, struct sock *sk, struct sk_buff *s
 {
 	struct ip_options *opt	= &(IPCB(skb)->opt);
 
-	__IP_INC_STATS(net, IPSTATS_MIB_OUTFORWDATAGRAMS);
-
 #ifdef CONFIG_NET_SWITCHDEV
 	if (skb->offload_l3_fwd_mark) {
 		consume_skb(skb);
@@ -130,6 +128,8 @@ int ip_forward(struct sk_buff *skb)
 	if (opt->is_strictroute && rt->rt_uses_gateway)
 		goto sr_failed;
 
+	__IP_INC_STATS(net, IPSTATS_MIB_OUTFORWDATAGRAMS);
+
 	IPCB(skb)->flags |= IPSKB_FORWARDED;
 	mtu = ip_dst_mtu_maybe_forward(&rt->dst, true);
 	if (ip_exceeds_mtu(skb, mtu)) {
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 54fc4c711f2c..8a9199ab97ef 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -448,10 +448,6 @@ static int ip6_forward_proxy_check(struct sk_buff *skb)
 static inline int ip6_forward_finish(struct net *net, struct sock *sk,
 				     struct sk_buff *skb)
 {
-	struct dst_entry *dst = skb_dst(skb);
-
-	__IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
-
 #ifdef CONFIG_NET_SWITCHDEV
 	if (skb->offload_l3_fwd_mark) {
 		consume_skb(skb);
@@ -619,6 +615,8 @@ int ip6_forward(struct sk_buff *skb)
 		}
 	}
 
+	__IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
+
 	mtu = ip6_dst_mtu_maybe_forward(dst, true);
 	if (mtu < IPV6_MIN_MTU)
 		mtu = IPV6_MIN_MTU;
-- 
2.35.2


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH 1/1] net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check
  2023-10-08  0:59 ` [PATCH 1/1] net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check Heng Guo
@ 2023-10-10 16:26   ` David Ahern
  2023-10-11  1:51   ` [PATCH] " Heng Guo
  1 sibling, 0 replies; 6+ messages in thread
From: David Ahern @ 2023-10-10 16:26 UTC (permalink / raw)
  To: Heng Guo, davem, edumazet, kuba, pabeni; +Cc: netdev, filip.pudak

On 10/7/23 6:59 PM, Heng Guo wrote:
> According to RFC 4293 "3.2.3. IP Statistics Tables",
>   +-------+------>------+----->-----+----->-----+
>   | InForwDatagrams (6) | OutForwDatagrams (6)  |
>   |                     V                       +->-+ OutFragReqds
>   |                 InNoRoutes                  |   | (packets)
>   / (local packet (3)                           |   |
>   |  IF is that of the address                  |   +--> OutFragFails
>   |  and may not be the receiving IF)           |   |    (packets)
> the IPSTATS_MIB_OUTFORWDATAGRAMS should be counted before fragment
> check.
> 
> The existing implementation, instead, would incease the counter after
> fragment check: ip_exceeds_mtu() in ipv4 and ip6_pkt_too_big() in ipv6.
> 
> So move IPSTATS_MIB_OUTFORWDATAGRAMS counter to ip_forward() for ipv4 and
> ip6_forward() for ipv6.
> 
> Reviewed-by: Filip Pudak <filip.pudak@windriver.com>
> Signed-off-by: Heng Guo <heng.guo@windriver.com>
> ---
>  net/ipv4/ip_forward.c | 4 ++--
>  net/ipv6/ip6_output.c | 6 ++----
>  2 files changed, 4 insertions(+), 6 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@kernel.org>

Please repost as just a single patch and add in the details from the
cover letter.


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check
  2023-10-08  0:59 ` [PATCH 1/1] net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check Heng Guo
  2023-10-10 16:26   ` David Ahern
@ 2023-10-11  1:51   ` Heng Guo
  2023-10-13 17:01     ` Jakub Kicinski
  2023-10-13 17:10     ` patchwork-bot+netdevbpf
  1 sibling, 2 replies; 6+ messages in thread
From: Heng Guo @ 2023-10-11  1:51 UTC (permalink / raw)
  To: davem, dsahern, edumazet, kuba, pabeni; +Cc: netdev, filip.pudak, heng.guo

Reproduce environment:
network with 3 VM linuxs is connected as below:
VM1<---->VM2(latest kernel 6.5.0-rc7)<---->VM3
VM1: eth0 ip: 192.168.122.207 MTU 1800
VM2: eth0 ip: 192.168.122.208, eth1 ip: 192.168.123.224 MTU 1500
VM3: eth0 ip: 192.168.123.240 MTU 1800

Reproduce:
VM1 send 1600 bytes UDP data to VM3 using tools scapy with flags='DF'.
scapy command:
send(IP(dst="192.168.123.240",flags='DF')/UDP()/str('0'*1600),count=1,
inter=1.000000)

Result:
Before IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
    ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
    OutDiscards OutNoRoutes ReasmTimeout ReasmReqdss
Ip: 1 64 6 0 2 2 0 0 2 4 0 0 0 0 0 0 0 0 0
......
root@qemux86-64:~#
----------------------------------------------------------------------
After IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
    ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
    OutDiscards OutNoRoutes ReasmTimeout ReasmReqdss
Ip: 1 64 7 0 2 2 0 0 2 5 0 0 0 0 0 0 0 1 0
......
root@qemux86-64:~#
----------------------------------------------------------------------
ForwDatagrams is always keeping 2 without increment.

Issue description and patch:
ip_exceeds_mtu() in ip_forward() drops this IP datagram because skb len
(1600 sending by scapy) is over MTU(1500 in VM2) if "DF" is set.
According to RFC 4293 "3.2.3. IP Statistics Tables",
  +-------+------>------+----->-----+----->-----+
  | InForwDatagrams (6) | OutForwDatagrams (6)  |
  |                     V                       +->-+ OutFragReqds
  |                 InNoRoutes                  |   | (packets)
  / (local packet (3)                           |   |
  |  IF is that of the address                  |   +--> OutFragFails
  |  and may not be the receiving IF)           |   |    (packets)
the IPSTATS_MIB_OUTFORWDATAGRAMS should be counted before fragment
check.
The existing implementation, instead, would incease the counter after
fragment check: ip_exceeds_mtu() in ipv4 and ip6_pkt_too_big() in ipv6.
So do patch to move IPSTATS_MIB_OUTFORWDATAGRAMS counter to ip_forward()
for ipv4 and ip6_forward() for ipv6.

Test result with patch:
Before IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
    ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
    OutDiscards OutNoRoutes ReasmTimeout ReasmReqdss
Ip: 1 64 6 0 2 2 0 0 2 4 0 0 0 0 0 0 0 0 0
......
root@qemux86-64:~#
----------------------------------------------------------------------
After IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
    ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
    OutDiscards OutNoRoutes ReasmTimeout ReasmReqdss
Ip: 1 64 7 0 2 3 0 0 2 5 0 0 0 0 0 0 0 1 0
......
root@qemux86-64:~#
----------------------------------------------------------------------
ForwDatagrams is updated from 2 to 3.

Reviewed-by: Filip Pudak <filip.pudak@windriver.com>
Signed-off-by: Heng Guo <heng.guo@windriver.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
---
 net/ipv4/ip_forward.c | 4 ++--
 net/ipv6/ip6_output.c | 6 ++----
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
index 66fac1216d46..8b65f12583eb 100644
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -66,8 +66,6 @@ static int ip_forward_finish(struct net *net, struct sock *sk, struct sk_buff *s
 {
 	struct ip_options *opt	= &(IPCB(skb)->opt);
 
-	__IP_INC_STATS(net, IPSTATS_MIB_OUTFORWDATAGRAMS);
-
 #ifdef CONFIG_NET_SWITCHDEV
 	if (skb->offload_l3_fwd_mark) {
 		consume_skb(skb);
@@ -130,6 +128,8 @@ int ip_forward(struct sk_buff *skb)
 	if (opt->is_strictroute && rt->rt_uses_gateway)
 		goto sr_failed;
 
+	__IP_INC_STATS(net, IPSTATS_MIB_OUTFORWDATAGRAMS);
+
 	IPCB(skb)->flags |= IPSKB_FORWARDED;
 	mtu = ip_dst_mtu_maybe_forward(&rt->dst, true);
 	if (ip_exceeds_mtu(skb, mtu)) {
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 54fc4c711f2c..8a9199ab97ef 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -448,10 +448,6 @@ static int ip6_forward_proxy_check(struct sk_buff *skb)
 static inline int ip6_forward_finish(struct net *net, struct sock *sk,
 				     struct sk_buff *skb)
 {
-	struct dst_entry *dst = skb_dst(skb);
-
-	__IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
-
 #ifdef CONFIG_NET_SWITCHDEV
 	if (skb->offload_l3_fwd_mark) {
 		consume_skb(skb);
@@ -619,6 +615,8 @@ int ip6_forward(struct sk_buff *skb)
 		}
 	}
 
+	__IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
+
 	mtu = ip6_dst_mtu_maybe_forward(dst, true);
 	if (mtu < IPV6_MIN_MTU)
 		mtu = IPV6_MIN_MTU;
-- 
2.35.2


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH] net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check
  2023-10-11  1:51   ` [PATCH] " Heng Guo
@ 2023-10-13 17:01     ` Jakub Kicinski
  2023-10-13 17:10     ` patchwork-bot+netdevbpf
  1 sibling, 0 replies; 6+ messages in thread
From: Jakub Kicinski @ 2023-10-13 17:01 UTC (permalink / raw)
  To: Heng Guo; +Cc: davem, dsahern, edumazet, pabeni, netdev, filip.pudak

On Wed, 11 Oct 2023 09:51:37 +0800 Heng Guo wrote:
> Subject: [PATCH] net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check

Applied, thank you!

For future reference - the net-next goes into the prefix (git
format-patch --subject-prefix="PATCH net-next") and does not 
replace the commit prefix. So:

[PATCH net-next] net: fix
       ^            \
   net-next here     this stays as net

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check
  2023-10-11  1:51   ` [PATCH] " Heng Guo
  2023-10-13 17:01     ` Jakub Kicinski
@ 2023-10-13 17:10     ` patchwork-bot+netdevbpf
  1 sibling, 0 replies; 6+ messages in thread
From: patchwork-bot+netdevbpf @ 2023-10-13 17:10 UTC (permalink / raw)
  To: Heng Guo; +Cc: davem, dsahern, edumazet, kuba, pabeni, netdev, filip.pudak

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 11 Oct 2023 09:51:37 +0800 you wrote:
> Reproduce environment:
> network with 3 VM linuxs is connected as below:
> VM1<---->VM2(latest kernel 6.5.0-rc7)<---->VM3
> VM1: eth0 ip: 192.168.122.207 MTU 1800
> VM2: eth0 ip: 192.168.122.208, eth1 ip: 192.168.123.224 MTU 1500
> VM3: eth0 ip: 192.168.123.240 MTU 1800
> 
> [...]

Here is the summary with links:
  - net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check
    https://git.kernel.org/netdev/net-next/c/cf8b49fbd041

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html



^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-10-13 17:10 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-10-08  0:59 [PATCH 0/1] Issue description and debug Heng Guo
2023-10-08  0:59 ` [PATCH 1/1] net-next: fix IPSTATS_MIB_OUTFORWDATAGRAMS increment after fragment check Heng Guo
2023-10-10 16:26   ` David Ahern
2023-10-11  1:51   ` [PATCH] " Heng Guo
2023-10-13 17:01     ` Jakub Kicinski
2023-10-13 17:10     ` patchwork-bot+netdevbpf

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