netdev - Re: [PATCH] xfrm: fix fragmentation on inter family tunnels

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Date:	Mon, 06 Apr 2009 17:43:57 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	steffen.klassert@...unet.com
Cc:	herbert@...dor.apana.org.au, netdev@...r.kernel.org
Subject: Re: [PATCH] xfrm: fix fragmentation on inter family tunnels

From: Steffen Klassert <steffen.klassert@...unet.com>
Date: Mon, 6 Apr 2009 15:58:50 +0200

> If an ipv4 packet (not locally generated with IP_DF flag not set) bigger
> than mtu size is supposed to go via a xfrm ipv6 tunnel, the packetsize
> check in xfrm4_tunnel_check_size() is omited and ipv6 drops the packet
> without sending a notice to the original sender of the ipv4 packet.
> 
> Another issue is that ipv4 connection tracking does reassembling of
> incomming fragmented packets. If such a reassembled packet is supposed to
> go via a xfrm ipv6 tunnel it will be droped, even if the original sender
> did proper fragmentation.
> 
> According to RFC 2473 (section 7) tunnel ipv6 packets resulting from the
> encapsulation of an original packet are considered as locally generated
> packets. If such a packet passed the checks in xfrm{4,6}_tunnel_check_size()
> fragmentation is allowed according to RFC 2473 (section 7.1/7.2).
> 
> This patch sets skb->local_df in xfrm6_prepare_output() to achieve
> fragmentation in this case.
> 
> Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>

Applied, thanks Steffen.
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