IPSec AH hardware offload

IPSec AH hardware offload

[Jamie Iles]

Hi,

I'm currently developing a driver for a hardware crypto offload engine that is
capable of offloading both ESP and AH in IPSec. I've noticed that none of the
crypto drivers in 2.6.28 do offload for ahash and that the netkey AH
implementation both use synchronous hashes. Are the synchronous software
versions likely to be more efficient than hardware offloading or is there an
architectural reason for not using async hashes?

Cheers,

    Jamie
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Re: IPSec AH hardware offload

[Herbert Xu]

Jamie Iles <jamie.iles@picochip.com> wrote:
> 
> I'm currently developing a driver for a hardware crypto offload engine that is
> capable of offloading both ESP and AH in IPSec. I've noticed that none of the
> crypto drivers in 2.6.28 do offload for ahash and that the netkey AH
> implementation both use synchronous hashes. Are the synchronous software
> versions likely to be more efficient than hardware offloading or is there an
> architectural reason for not using async hashes?

No it's just because nobody has gotten around to complete the
async hash work yet.  So we're currently half-way through the
process of converting existing algorithms to the shash interface,
which allows them to be used efficiently by IPsec through the
ahash interface.

Once that's completed we can then convert IPsec (or rather, authenc)
over to using ahash.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: IPSec AH hardware offload

[Jamie Iles]

Herbert Xu wrote:
> Once that's completed we can then convert IPsec (or rather, authenc)
> over to using ahash.
Does that include the hash for authentication header in 
net/ipv[46]/ah[46].c?

The driver implements authenc algorithms, so we'll already get 
asynchronous operation for ESP, but the crypto_alloc_hash() in ah[46].c 
explicitly requests a synchronous hash. Is this worth converting to use 
ahash?

Thanks,

Jamie

Re: IPSec AH hardware offload

[Herbert Xu]

On Wed, Jan 28, 2009 at 08:36:19AM +0000, Jamie Iles wrote:
>
> Does that include the hash for authentication header in  
> net/ipv[46]/ah[46].c?

Yes.

> The driver implements authenc algorithms, so we'll already get  
> asynchronous operation for ESP, but the crypto_alloc_hash() in ah[46].c  
> explicitly requests a synchronous hash. Is this worth converting to use  
> ahash?

Whether it's worth it depends on how much you're being paid :)
But it certainly wouldn't hurt, provided that someone is willing
to do the work.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt