Subject: [PATCH] crypto: atmel-aes - properly set IV after {en,de}crypt

From: [email-masked] (Boris Brezillon)
Date: Tue, 10 Oct 2017 16:16:59 +0200

Hi Romain,

May I ask why you're sending this patch to the MTD ML?

While I'm here, can you have a look at this patch [1] and add you
Reviewed-by/Tested-by?

Thanks,

Boris

[1]http://patchwork.ozlabs.org/patch/821959/

On Fri,  6 Oct 2017 17:51:08 +0200
Romain Izard <[email-masked]> wrote:

> Certain cipher modes like CTS expect the IV (req->info) of
> ablkcipher_request (or equivalently req->iv of skcipher_request) to
> contain the last ciphertext block when the {en,de}crypt operation is done.
> 
> Fix this issue for the Atmel AES hardware engine. The tcrypt test
> case for cts(cbc(aes)) is now correctly passed.
> 
> To handle the case of in-place decryption, copy the ciphertext in an
> intermediate buffer before decryption.
> 
> Signed-off-by: Romain Izard <[email-masked]>
> ---
>  drivers/crypto/atmel-aes.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/crypto/atmel-aes.c b/drivers/crypto/atmel-aes.c
> index 29e20c37f3a6..f22300babb45 100644
> --- a/drivers/crypto/atmel-aes.c
> +++ b/drivers/crypto/atmel-aes.c
> @@ -156,6 +156,7 @@ struct atmel_aes_authenc_ctx {
>  
>  struct atmel_aes_reqctx {
>  	unsigned long		mode;
> +	u8			*backup_info;
>  };
>  
>  #ifdef CONFIG_CRYPTO_DEV_ATMEL_AUTHENC
> @@ -496,6 +497,12 @@ static void atmel_aes_authenc_complete(struct atmel_aes_dev *dd, int err);
>  
>  static inline int atmel_aes_complete(struct atmel_aes_dev *dd, int err)
>  {
> +	struct ablkcipher_request *req = ablkcipher_request_cast(dd->areq);
> +	struct crypto_ablkcipher *ablkcipher = crypto_ablkcipher_reqtfm(req);
> +	struct atmel_aes_reqctx *rctx = ablkcipher_request_ctx(req);
> +	int ivsize = crypto_ablkcipher_ivsize(ablkcipher);
> +	bool enc = atmel_aes_is_encrypt(dd);
> +
>  #ifdef CONFIG_CRYPTO_DEV_ATMEL_AUTHENC
>  	atmel_aes_authenc_complete(dd, err);
>  #endif
> @@ -503,6 +510,15 @@ static inline int atmel_aes_complete(struct atmel_aes_dev *dd, int err)
>  	clk_disable(dd->iclk);
>  	dd->flags &= ~AES_FLAGS_BUSY;
>  
> +	if (enc) {
> +		scatterwalk_map_and_copy(req->info, req->dst,
> +					 req->nbytes - ivsize, ivsize, 0);
> +	} else if (rctx->backup_info) {
> +		memcpy(req->info, rctx->backup_info, ivsize);
> +		kfree(rctx->backup_info);
> +		rctx->backup_info = NULL;
> +	}
> +
>  	if (dd->is_async)
>  		dd->areq->complete(dd->areq, err);
>  
> @@ -959,13 +975,25 @@ static int atmel_aes_transfer_complete(struct atmel_aes_dev *dd)
>  static int atmel_aes_start(struct atmel_aes_dev *dd)
>  {
>  	struct ablkcipher_request *req = ablkcipher_request_cast(dd->areq);
> +	struct crypto_ablkcipher *ablkcipher = crypto_ablkcipher_reqtfm(req);
>  	struct atmel_aes_reqctx *rctx = ablkcipher_request_ctx(req);
> +	int ivsize = crypto_ablkcipher_ivsize(ablkcipher);
> +	bool enc = atmel_aes_is_encrypt(dd);
>  	bool use_dma = (req->nbytes >= ATMEL_AES_DMA_THRESHOLD ||
>  			dd->ctx->block_size != AES_BLOCK_SIZE);
>  	int err;
>  
>  	atmel_aes_set_mode(dd, rctx);
>  
> +	if (!enc) {
> +		rctx->backup_info = kzalloc(ivsize, GFP_KERNEL);
> +		if (rctx->backup_info == NULL)
> +			return atmel_aes_complete(dd, -ENOMEM);
> +
> +		scatterwalk_map_and_copy(rctx->backup_info, req->src,
> +				 (req->nbytes - ivsize), ivsize, 0);
> +	}
> +
>  	err = atmel_aes_hw_init(dd);
>  	if (err)
>  		return atmel_aes_complete(dd, err);