Re: [Xen-devel] Xen checksumming bug with IPsec ESP packets

["Jonathan M. McCune" <jmmccune@xxxxxxxxxxx>]

I can test patches until the end of August.

Cheers,
-Jon


Nivedita Singhvi wrote:

> Keir Fraser wrote:
>
> > On 3 Aug 2005, at 17:27, Jonathan M. McCune wrote:
> >
> > > We fixed this by removing the addition of flag NETIF_F_IP_CSUM in 
> > > drivers/xen/netfront/netfront.c:create_netdev().  I believe this 
> > > tells the kernel to just always do the checksum in software.  Thus, 
> > > the broken optimization for TCP/UDP packets gets bypassed.
> > > Permanent Solution:
> > >
> > > ???
> > >
> > > That's why I posted this message... :-)
> >
> > I suspect the ESP code would need to be made aware of the csum_blank 
> > field, and fill in before forwarding. There are doubtless other paths 
> > that may need similar tweaks (e.g., NAT IP masquerading is untested I 
> > think, although there's a fair chance it'll just work).
> > Apart from the above 'proper fix', simple not-so-hacky solutions 
> > include:
> >  * Run 'ethtool -K tx off' in each domU
> >  * Add an option to netback in domain0 to fill in checksums itself if 
> > not done by domU.
> >  * Allow netback to advertise to domUs whether it accepts 
> > non-checksummed packets, and have an option to set this advertisement 
> > when you start netback.
> Keir, Jonathan,
>
> I stuck the above in a bugzilla entry (#143) just for better
> tracking.  Jonathan, would you be able to test patches?
>
> thanks,
> Nivedita

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