linux-kernel - Re: [RFC PATCH crypto 4/4] AES-NI: Add support to Intel AES-NI instructions for x86

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Date:	Tue, 13 Jan 2009 10:34:13 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	Sebastian Siewior <linux-crypto@...breakpoint.cc>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>
Subject: Re: [RFC PATCH crypto 4/4] AES-NI: Add support to Intel AES-NI
	instructions for x86_64 platform

On Mon, 2009-01-12 at 18:43 +0800, Herbert Xu wrote:
> On Mon, Jan 12, 2009 at 02:55:10PM +0800, Huang Ying wrote:
> >
> > I use a "shell" cbc(aes) algorithm which chooses between
> > cryptd(__cbc-aes-aesni) and __cbc-aes-aesni according to context. But
> > the struct ablkcipher_request passed in can not be used for cryptd(*).
> > This can be resolved by allocating another struct ablkcipher_request for
> > cryptd(*) for each incoming struct ablkcipher_request. But is there any
> > better solution?
> 
> You should include that other ablkcipher_request as part of the
> context of your ablkcipher_request.
> 
> See for example how aead embeds it.

Thank you! I take a look at gcm.c, and know how to implement it.

I have another idea, the sample code is as follow. In short, just relay
the request to cryptd_tfm, and change tfm before/after.

struct async_aes_ctx {
        struct crypto_ablkcipher *cryptd_tfm;
};

struct async_aes_req_ctx {
        struct crypto_ablkcipher *ablk_tfm;
        crypto_completion_t complete;
};

static inline struct async_aes_req_ctx *ablk_aes_req_ctx(
        struct ablkcipher_request *req,
        struct crypto_ablkcipher *ablk_tfm) {
        return ablkcipher_request_ctx(req) +
                ablk_tfm->base.crt_ablkcipher.reqsize;
}

static void ablk_complete(struct crypto_async_request *req, int err)
{
        struct ablkcipher_request *ablk_req = ablkcipher_request_cast(req);
        struct async_aes_req_ctx *req_ctx =
                ablk_aes_req_ctx(ablk_req, crypto_ablkcipher_reqtfm(ablk_req));
        ablkcipher_request_set_tfm(ablk_req, req_ctx->ablk_tfm);
        req_ctx->complete(req, err);
}

static int ablk_encrypt(struct ablkcipher_request *req)
{
        struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
        struct async_aes_ctx *ctx = crypto_ablkcipher_ctx(tfm);

        if (kernel_fpu_using()) {
                struct async_aes_req_ctx *req_ctx =
                        ablk_aes_req_ctx(req, ctx->cryptd_tfm);
                req_ctx->ablk_tfm = tfm;
                ablkcipher_request_set_tfm(req, ctx->cryptd_tfm);
                req_ctx->complete = req->base.complete;
                req->base.complete = ablk_complete;
                return crypto_ablkcipher_encrypt(req);
        } else {
                struct blkcipher_desc desc;
                desc.tfm = cryptd_ablkcipher_child(ctx->cryptd_tfm);
                desc.info = req->info;
                desc.flags = 0;
                return crypto_blkcipher_encrypt(&desc, req->dst, req->src,
                                                req->nbytes);
        }
}

static void ablk_init_common(struct crypto_tfm *tfm,
                             struct crypto_ablkcipher *cryptd_tfm)
{
        struct async_aes_ctx *ctx = crypto_tfm_ctx(tfm);

        ctx->cryptd_tfm = cryptd_tfm;
        tfm->crt_ablkcipher.reqsize = cryptd_tfm->base.crt_ablkcipher.reqsize +
                sizeof(struct async_aes_req_ctx);
}

static int ablk_ecb_init(struct crypto_tfm *tfm)
{
        struct crypto_ablkcipher *cryptd_tfm;

        cryptd_tfm = cryptd_alloc_ablkcipher("__ecb-aes-aesni", 0, 0);
        if (IS_ERR(cryptd_tfm))
                return PTR_ERR(cryptd_tfm);
        ablk_init_common(tfm, cryptd_tfm);
        return 0;
}

Best Regards,
Huang Ying


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