[v2,1/2] ip_tunnel: fix ip tunnel lookup in collect_md mode

Submitted by Haishuang Yan on June 17, 2017, 3:27 a.m.

Details

Message ID 1497670031-2971-1-git-send-email-yanhaishuang@cmss.chinamobile.com
State Changes Requested
Delegated to: David Miller
Headers show

Commit Message

Haishuang Yan June 17, 2017, 3:27 a.m.
In collect_md mode, if the tun dev is down, it still can call
ip_tunnel_rcv to receive on packets, and the rx statistics increase
improperly.

Fixes: 2e15ea390e6f ("ip_gre: Add support to collect tunnel metadata.")
Cc: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>

---
Change since v2:
  * Fix wrong recipient addresss
---
 net/ipv4/ip_tunnel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

pravin shelar June 19, 2017, 5:43 a.m.
On Fri, Jun 16, 2017 at 8:27 PM, Haishuang Yan
<yanhaishuang@cmss.chinamobile.com> wrote:
> In collect_md mode, if the tun dev is down, it still can call
> ip_tunnel_rcv to receive on packets, and the rx statistics increase
> improperly.
>
> Fixes: 2e15ea390e6f ("ip_gre: Add support to collect tunnel metadata.")
> Cc: Pravin B Shelar <pshelar@nicira.com>
> Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
>
> ---
> Change since v2:
>   * Fix wrong recipient addresss
> ---
>  net/ipv4/ip_tunnel.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
> index 0f1d876..a3caba1 100644
> --- a/net/ipv4/ip_tunnel.c
> +++ b/net/ipv4/ip_tunnel.c
> @@ -176,7 +176,7 @@ struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
>                 return cand;
>
>         t = rcu_dereference(itn->collect_md_tun);
> -       if (t)
> +       if (t && (t->dev->flags & IFF_UP))
>                 return t;
>
It would be nice if we could increment drop count if tunnel device is not up.
Haishuang Yan June 19, 2017, 1:13 p.m.
> On 19 Jun 2017, at 1:43 PM, Pravin Shelar <pshelar@ovn.org> wrote:
> 
> On Fri, Jun 16, 2017 at 8:27 PM, Haishuang Yan
> <yanhaishuang@cmss.chinamobile.com> wrote:
>> In collect_md mode, if the tun dev is down, it still can call
>> ip_tunnel_rcv to receive on packets, and the rx statistics increase
>> improperly.
>> 
>> Fixes: 2e15ea390e6f ("ip_gre: Add support to collect tunnel metadata.")
>> Cc: Pravin B Shelar <pshelar@nicira.com>
>> Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
>> 
>> ---
>> Change since v2:
>>  * Fix wrong recipient addresss
>> ---
>> net/ipv4/ip_tunnel.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
>> index 0f1d876..a3caba1 100644
>> --- a/net/ipv4/ip_tunnel.c
>> +++ b/net/ipv4/ip_tunnel.c
>> @@ -176,7 +176,7 @@ struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
>>                return cand;
>> 
>>        t = rcu_dereference(itn->collect_md_tun);
>> -       if (t)
>> +       if (t && (t->dev->flags & IFF_UP))
>>                return t;
>> 
> It would be nice if we could increment drop count if tunnel device is not up.
> 
Hi Pravin

I think it’s not necessary, for example as gre tunnel, if ipgre_rcv fails, it would trigger send an icmp unreachable
message:

	if (ipgre_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
		return 0;

	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);

Since the tunnel device didn’t touch the packets, so increase drop statistics is not necessary.

Thanks
pravin shelar June 19, 2017, 6:08 p.m.
On Mon, Jun 19, 2017 at 6:13 AM, 严海双 <yanhaishuang@cmss.chinamobile.com> wrote:
>
>
>> On 19 Jun 2017, at 1:43 PM, Pravin Shelar <pshelar@ovn.org> wrote:
>>
>> On Fri, Jun 16, 2017 at 8:27 PM, Haishuang Yan
>> <yanhaishuang@cmss.chinamobile.com> wrote:
>>> In collect_md mode, if the tun dev is down, it still can call
>>> ip_tunnel_rcv to receive on packets, and the rx statistics increase
>>> improperly.
>>>
>>> Fixes: 2e15ea390e6f ("ip_gre: Add support to collect tunnel metadata.")
>>> Cc: Pravin B Shelar <pshelar@nicira.com>
>>> Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
>>>
>>> ---
>>> Change since v2:
>>>  * Fix wrong recipient addresss
>>> ---
>>> net/ipv4/ip_tunnel.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
>>> index 0f1d876..a3caba1 100644
>>> --- a/net/ipv4/ip_tunnel.c
>>> +++ b/net/ipv4/ip_tunnel.c
>>> @@ -176,7 +176,7 @@ struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
>>>                return cand;
>>>
>>>        t = rcu_dereference(itn->collect_md_tun);
>>> -       if (t)
>>> +       if (t && (t->dev->flags & IFF_UP))
>>>                return t;
>>>
>> It would be nice if we could increment drop count if tunnel device is not up.
>>
> Hi Pravin
>
> I think it’s not necessary, for example as gre tunnel, if ipgre_rcv fails, it would trigger send an icmp unreachable
> message:
>
>         if (ipgre_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
>                 return 0;
>
>         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
>
> Since the tunnel device didn’t touch the packets, so increase drop statistics is not necessary.
>
icmp err packets are not reliable on all networks. device stats are
much more convenient during debugging connectivity issues.
Haishuang Yan June 21, 2017, 10:40 a.m.
> On 20 Jun 2017, at 2:08 AM, Pravin Shelar <pshelar@ovn.org> wrote:
> 
> On Mon, Jun 19, 2017 at 6:13 AM, 严海双 <yanhaishuang@cmss.chinamobile.com> wrote:
>> 
>> 
>>> On 19 Jun 2017, at 1:43 PM, Pravin Shelar <pshelar@ovn.org> wrote:
>>> 
>>> On Fri, Jun 16, 2017 at 8:27 PM, Haishuang Yan
>>> <yanhaishuang@cmss.chinamobile.com> wrote:
>>>> In collect_md mode, if the tun dev is down, it still can call
>>>> ip_tunnel_rcv to receive on packets, and the rx statistics increase
>>>> improperly.
>>>> 
>>>> Fixes: 2e15ea390e6f ("ip_gre: Add support to collect tunnel metadata.")
>>>> Cc: Pravin B Shelar <pshelar@nicira.com>
>>>> Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
>>>> 
>>>> ---
>>>> Change since v2:
>>>> * Fix wrong recipient addresss
>>>> ---
>>>> net/ipv4/ip_tunnel.c | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>> 
>>>> diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
>>>> index 0f1d876..a3caba1 100644
>>>> --- a/net/ipv4/ip_tunnel.c
>>>> +++ b/net/ipv4/ip_tunnel.c
>>>> @@ -176,7 +176,7 @@ struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
>>>>               return cand;
>>>> 
>>>>       t = rcu_dereference(itn->collect_md_tun);
>>>> -       if (t)
>>>> +       if (t && (t->dev->flags & IFF_UP))
>>>>               return t;
>>>> 
>>> It would be nice if we could increment drop count if tunnel device is not up.
>>> 
>> Hi Pravin
>> 
>> I think it’s not necessary, for example as gre tunnel, if ipgre_rcv fails, it would trigger send an icmp unreachable
>> message:
>> 
>>        if (ipgre_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
>>                return 0;
>> 
>>        icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
>> 
>> Since the tunnel device didn’t touch the packets, so increase drop statistics is not necessary.
>> 
> icmp err packets are not reliable on all networks. device stats are
> much more convenient during debugging connectivity issues.
> 

Okay, if the tunnel device is not up, packets will transfer to fallback tunnel, and if 
the fallback device is up, the RX drops will be increased as expected:

gre0: flags=193<UP,RUNNING,NOARP>  mtu 1476
        inet 172.16.20.1  netmask 255.255.255.0
        unspec 00-00-00-00-00-00-F0-00-00-00-00-00-00-00-00-00  txqueuelen 1000  (UNSPEC)
        RX packets 105  bytes 4522 (4.4 KiB)
        RX errors 0  dropped 105  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

My question is  whether we should increase the drops of original tunnel device 
instead of fallback device?

Patch hide | download patch | download mbox

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 0f1d876..a3caba1 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -176,7 +176,7 @@  struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
 		return cand;
 
 	t = rcu_dereference(itn->collect_md_tun);
-	if (t)
+	if (t && (t->dev->flags & IFF_UP))
 		return t;
 
 	if (itn->fb_tunnel_dev && itn->fb_tunnel_dev->flags & IFF_UP)