linux-kernel - Re: [PATCH V6 5/7] crypto: AES CBC multi-buffer glue code

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Date:   Tue, 18 Jul 2017 13:41:42 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Megha Dey <megha.dey@...ux.intel.com>
Cc:     tim.c.chen@...ux.intel.com, davem@...emloft.net,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        megha.dey@...el.com
Subject: Re: [PATCH V6 5/7] crypto: AES CBC multi-buffer glue code

On Tue, Jun 27, 2017 at 05:26:13PM -0700, Megha Dey wrote:
>
> +static void completion_callback(struct mcryptd_skcipher_request_ctx *rctx,
> +			    struct mcryptd_alg_cstate *cstate,
> +			    int err)
> +{
> +	struct skcipher_request *req = cast_mcryptd_ctx_to_req(rctx);
> +
> +       /* remove from work list and invoke completion callback */
> +	spin_lock(&cstate->work_lock);
> +	list_del(&rctx->waiter);
> +	spin_unlock(&cstate->work_lock);
> +
> +	if (irqs_disabled())
> +		rctx->complete(&req->base, err);
> +	else {
> +		local_bh_disable();
> +		rctx->complete(&req->base, err);
> +		local_bh_enable();
> +	}
> +}

The fact that you need to do this check means that this design is
wrong.  You should always know what context you are in.

> +/*
> + * CRYPTO_ALG_ASYNC flag is passed to indicate we have an ablk
> + * scatter-gather walk.
> + */
> +static struct skcipher_alg aes_cbc_mb_alg = {
> +	.base = {
> +		.cra_name		= "cbc(aes)",
> +		.cra_driver_name	= "cbc-aes-aesni-mb",
> +		.cra_priority		= 500,
> +		.cra_flags		= CRYPTO_ALG_INTERNAL,
> +		.cra_blocksize		= AES_BLOCK_SIZE,
> +		.cra_ctxsize		= CRYPTO_AES_CTX_SIZE,
> +		.cra_module		= THIS_MODULE,
> +	},
> +	.min_keysize	= AES_MIN_KEY_SIZE,
> +	.max_keysize	= AES_MAX_KEY_SIZE,
> +	.ivsize		= AES_BLOCK_SIZE,
> +	.setkey		= aes_set_key,
> +	.encrypt	= mb_aes_cbc_encrypt,
> +	.decrypt	= mb_aes_cbc_decrypt
> +};

So this claims to be a sync algorithm.  Is this really the case?

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt