Re: [PATCH v4 3/3] crypto: Add Allwinner Security System crypto accelerator
From: Corentin LABBE
Date: Sat Jul 26 2014 - 10:01:35 EST
Le 24/07/2014 15:38, Herbert Xu a écrit :
> On Thu, Jul 24, 2014 at 01:04:55PM +0200, Corentin LABBE wrote:
>> Le 24/07/2014 08:00, Herbert Xu a écrit :
>>> On Sat, Jul 12, 2014 at 02:59:13PM +0200, LABBE Corentin wrote:
>>>> +/* sunxi_hash_init: initialize request context
>>>> + * Activate the SS, and configure it for MD5 or SHA1
>>>> + */
>>>> +int sunxi_hash_init(struct ahash_request *areq)
>>>> + const char *hash_type;
>>>> + struct crypto_ahash *tfm = crypto_ahash_reqtfm(areq);
>>>> + struct sunxi_req_ctx *op = crypto_ahash_ctx(tfm);
>>>> + mutex_lock(&ss->lock);
>>>> + hash_type = crypto_tfm_alg_name(areq->base.tfm);
>>>> + op->byte_count = 0;
>>>> + op->nbwait = 0;
>>>> + op->waitbuf = 0;
>>>> + /* Enable and configure SS for MD5 or SHA1 */
>>>> + if (strcmp(hash_type, "sha1") == 0)
>>>> + op->mode = SS_OP_SHA1;
>>>> + else
>>>> + op->mode = SS_OP_MD5;
>>>> + writel(op->mode | SS_ENABLED, ss->base + SS_CTL);
>>>> + return 0;
>>> The hash driver is completely broken. You are modifying tfm
>>> ctx data which is shared by all users of a single tfm. So
>>> if two users conduct hashes in parallel they will step all
>>> over each other.
>> So where can I store data for each request ?
> Well, first of all you need to stop storing state in the hardware.
> After each operation the hardware may be used by some other user
> for a completely different hash request. So leaving the hash state
> in the hardware is a no-no.
> If your hardware supports exporting the hash state then you just
> have to export it after each operation and reimporting before the
> next one.
Even if it is undocumented, the hardware seems to support it.
Since crypto_ahash_ctx is for a tfm, does ahash_request_ctx is the good place to store data ?
(after a call to crypto_ahash_set_reqsize in cra_init)
I have also seen export/import function, does I need to use it ?
> If your hardware is incapable of exporting partial hash state then
> you will have to use a software fallback for init/update. If your
> hardware is incapable of importing partial hash state then you will
> also have to do finup/final using a software fallback.
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