The flow of the complete function (xxx_done) in gcm.c is as follow:

void complete(struct crypto_async_request *areq, int err)
{
	struct aead_request *req = areq->data;

	if (!err) {
		err = async_next_step();
		if (err == -EINPROGRESS || err == -EBUSY)
			return;
	}

	complete_for_next_step(areq, err);
}

But *areq may be destroyed in async_next_step(), this makes
complete_for_next_step() can not work properly. To fix this, one of
following methods is used for each complete function.

- Add a __complete() for each complete(), which accept struct
  aead_request *req instead of areq, so avoid using areq after it is
  destroyed.

- Expand complete_for_next_step().

The fixing method is based on the idea of Herbert Xu.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Remove the dedicated GHASH implementation in GCM, and uses the GHASH
digest algorithm instead. This will make GCM uses hardware accelerated
GHASH implementation automatically if available.

ahash instead of shash interface is used, because some hardware
accelerated GHASH implementation needs asynchronous interface.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This patch introduces the rfc4106 wrapper for GCM just as we have an
rfc4309 wrapper for CCM.  The purpose of the wrapper is to include part
of the IV in the key so that it can be negotiated by IPsec.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This patch converts the gcm algorithm over to crypto_grab_skcipher
which is a prerequisite for IV generation.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This patch adds the gcm_base template which takes a block cipher
parameter instead of cipher.  This allows the user to specify a
specific CTR implementation.

This also fixes a leak of the cipher algorithm that was previously
looked up but never freed.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This patch adds the necessary changes for GCM to be used with async
ciphers.  This would allow it to be used with hardware devices that
support CTR.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

As discussed previously, this patch moves the basic CTR functionality
into a chainable algorithm called ctr.  The IPsec-specific variant of
it is now placed on top with the name rfc3686.

So ctr(aes) gives a chainable cipher with IV size 16 while the IPsec
variant will be called rfc3686(ctr(aes)).  This patch also adjusts
gcm accordingly.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This patch fixes the request context alignment so that it is actually
aligned to the value required by the algorithm.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

The abreq structure is currently allocated on the stack.  This is broken
if the underlying algorithm is asynchronous.  This patch changes it so
that it's taken from the private context instead which has been enlarged
accordingly.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Unfortunately the generic chaining hasn't been ported to all architectures
yet, and notably not s390.  So this patch restores the chainging that we've
been using previously which does work everywhere.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>