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From: Steffen Klassert <steffen.klassert@secunet•com>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: David Miller <davem@davemloft•net>,
	Herbert Xu <herbert@gondor•apana.org.au>,
	netdev@vger•kernel.org
Subject: Re: [PATCH 2/3] ipv4: Fix packet size calculation for IPsec packets in __ip_append_data
Date: Mon, 6 Jun 2011 10:52:47 +0200	[thread overview]
Message-ID: <20110606085247.GE31505@secunet.com> (raw)
In-Reply-To: <1307345899.3098.3.camel@edumazet-laptop>

On Mon, Jun 06, 2011 at 09:38:19AM +0200, Eric Dumazet wrote:
> 
> Woh, I am afraid I wont have time in following days to check your
> assertion.

My test setup was the following:

I use an IPsec tunnel with tunnel endpoints 192.168.1.1 and 192.168.1.2

Then I do at 192.168.1.2

ping -c1 -M do -s 1410 192.168.1.1

PING 192.168.1.1 (192.168.1.1) 1410(1438) bytes of data.
>From 192.168.1.2 icmp_seq=1 Frag needed and DF set (mtu = 1438)

--- 192.168.1.1 ping statistics ---
0 packets transmitted, 0 received, +1 errors

So the packet matches the mtu but it is not send.
I used a kernel with your patch as head commit.

Reverting your patch (going one commit deeper in the history):

ping -c1 -M do -s 1410 192.168.1.1

PING 192.168.1.1 (192.168.1.1) 1410(1438) bytes of data.
1418 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=3.01 ms

--- 192.168.1.1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 3.014/3.014/3.014/0.000 ms

> 
> What about original problem then, how should we fix it ?
> 

Hm, I don't know. I'll try to reproduce it here.

> We do have some cases where at least one fragment (the last one) is
> oversized.

trailer_len is used only on IPsec so the poroblem exists only when
using IPsec, right?

> 
> I remember I used Nick Bowler scripts at that time, I might find them
> again...

Would be nice if you could provide these scripts and some informations
on how to reproduce the problem.


  reply	other threads:[~2011-06-06  8:49 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-06  6:46 [PATCH 1/3] xfrm: Fix off by one in the replay advance functions Steffen Klassert
2011-06-06  6:48 ` [PATCH 2/3] ipv4: Fix packet size calculation for IPsec packets in __ip_append_data Steffen Klassert
2011-06-06  7:38   ` Eric Dumazet
2011-06-06  8:52     ` Steffen Klassert [this message]
2011-06-07  5:06       ` Eric Dumazet
2011-06-08  5:30         ` Steffen Klassert
2011-06-09 21:47           ` David Miller
2011-06-22 11:02             ` Steffen Klassert
2011-06-28  3:39               ` David Miller
2011-06-30  9:06                 ` Steffen Klassert
2011-06-06  6:48 ` [PATCH 3/3] ipv4: Fix packet size calculation for raw " Steffen Klassert
2011-06-09 21:50   ` David Miller
2011-06-08  4:15 ` [PATCH 1/3] xfrm: Fix off by one in the replay advance functions David Miller

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