netdev - Re: [PATCH] IPsec NAT-T issue

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Message-ID: <20160617102429.GH7698@gauss.secunet.com>
Date:	Fri, 17 Jun 2016 12:24:29 +0200
From:	Steffen Klassert <steffen.klassert@...unet.com>
To:	Blair Steven <Blair.Steven@...iedtelesis.co.nz>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Herbert Xu <herbert@...dor.apana.org.au>
Subject: Re: [PATCH] IPsec NAT-T issue

On Wed, Jun 15, 2016 at 12:44:54AM +0000, Blair Steven wrote:
> The restoration is happening - but being actioned on the wrong location.
> 
> The destination IP address is being saved and restored, and the SPI 
> being written directly after the destination IP address. From my 
> understanding though, the ESN shuffling should have saved and restored 
> the UDP source / dest ports + SPI.

Yes, looks like we copy with a wrong offset if udp encapsulation
is used, skb_transport_header() does not point to the esp header
in this case. Ccing Herbert, he changed this part when switching
to the new AEAD interface with
commit 7021b2e1cddd ("esp4: Switch to new AEAD interface").

> 
> -Blair
> 
> On 06/13/2016 10:20 PM, Steffen Klassert wrote:
> > On Mon, Jun 13, 2016 at 11:48:13AM +1200, Blair Steven wrote:
> >> During testing we have discovered an issue with IPsec NAT-T where the SPI
> >> is over writing the source and dest ports of the UDP header.
> > The headers should be restored after the crypto operation in
> > esp_restore_header(). Does this not happen in your case? What
> > kind of problem do you experience?
> >