linux-kernel - Re: [PATCH 1/7] crypto: qce: common: Add MAC failed error checking

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Date:   Mon, 5 Apr 2021 12:36:00 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     herbert@...dor.apana.org.au, davem@...emloft.net,
        ebiggers@...gle.com, ardb@...nel.org, sivaprak@...eaurora.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/7] crypto: qce: common: Add MAC failed error checking

On Thu 25 Feb 12:27 CST 2021, Thara Gopinath wrote:

> MAC_FAILED gets set in the status register if authenthication fails
> for ccm algorithms(during decryption). Add support to catch and flag
> this error.
> 
> Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
> ---
>  drivers/crypto/qce/common.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/crypto/qce/common.c b/drivers/crypto/qce/common.c
> index dceb9579d87a..7c3cb483749e 100644
> --- a/drivers/crypto/qce/common.c
> +++ b/drivers/crypto/qce/common.c
> @@ -403,7 +403,8 @@ int qce_start(struct crypto_async_request *async_req, u32 type)
>  }
>  
>  #define STATUS_ERRORS	\
> -		(BIT(SW_ERR_SHIFT) | BIT(AXI_ERR_SHIFT) | BIT(HSD_ERR_SHIFT))
> +		(BIT(SW_ERR_SHIFT) | BIT(AXI_ERR_SHIFT) |	\
> +		 BIT(HSD_ERR_SHIFT) | BIT(MAC_FAILED_SHIFT))
>  
>  int qce_check_status(struct qce_device *qce, u32 *status)
>  {
> @@ -417,8 +418,12 @@ int qce_check_status(struct qce_device *qce, u32 *status)
>  	 * use result_status from result dump the result_status needs to be byte
>  	 * swapped, since we set the device to little endian.
>  	 */
> -	if (*status & STATUS_ERRORS || !(*status & BIT(OPERATION_DONE_SHIFT)))
> -		ret = -ENXIO;
> +	if (*status & STATUS_ERRORS || !(*status & BIT(OPERATION_DONE_SHIFT))) {
> +		if (*status & BIT(MAC_FAILED_SHIFT))

Afaict MAC_FAILED indicates a different category of errors from the
others. So I would prefer that the conditionals are flattened.

Is OPERATION_DONE set when MAC_FAILED?

If so:

if (errors || !done)
	return -ENXIO;
else if (*status & BIT(MAC_FAILED))
	return -EBADMSG;

Would be cleaner in my opinion.

Regards,
Bjorn

> +			ret = -EBADMSG;
> +		else
> +			ret = -ENXIO;
> +	}
>  
>  	return ret;
>  }
> -- 
> 2.25.1
>