[PATCH] optee/rpmb.c: Fix driver routing memory alignment using a temporary buffer

[Heinrich Schuchardt]

On 08.06.21 12:07, Timothée Cercueil wrote:
> From: Timothée Cercueil <timothee.cercueil at st.com>
>
> OP-TEE OS inserts a 6-byte header before a raw RPMB frame which makes
> RPMB data buffer not 32bit aligned. Many RPMB drivers implicitly expect
> 32bit alignment of the eMMC frame including arm_pl180_mmci.c, sandbox_mmc.c
> and stm32_sdmmc2.c

Generally block device drivers expect ARCH_DMA_MINALIGN. Have a look at
mmc_rpmb_read(), mmc_rpmb_write().

Why would we care about alignment in two different modules:
drivers/tee/optee/rpmb.c and drivers/mmc/rpmb.c?

Shouldn't the fix be in drivers/mmc/rpmb.c?

Let't include the MMC maintainer in the discussion.

Best regards

Heinrich

>
> To prevent breaking ABI with OPTEE-OS RPC memrefs, allocate a temporary
> buffer to copy the data into an aligned memory.
>
> Signed-off-by: Timothée Cercueil <timothee.cercueil at st.com>
> Change-Id: Id78d638851a666a35af907ca8de71dae00946457
> Signed-off-by: Timothée Cercueil <litchi.pi at protonmail.com>
> ---
>  drivers/tee/optee/rpmb.c | 24 +++++++++++++++++++++---
>  1 file changed, 21 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c
> index 0804fc963c..4713df711c 100644
> --- a/drivers/tee/optee/rpmb.c
> +++ b/drivers/tee/optee/rpmb.c
> @@ -122,6 +122,10 @@ static u32 rpmb_process_request(struct optee_private *priv, void *req,
>  {
>  	struct rpmb_req *sreq = req;
>  	struct mmc *mmc;
> +	void *rpmb_data;
> +	void *rpmb_frame_buffer = NULL;
> +	size_t rpmb_data_sz;
> +	int ret;
>
>  	if (req_size < sizeof(*sreq))
>  		return TEE_ERROR_BAD_PARAMETERS;
> @@ -131,9 +135,23 @@ static u32 rpmb_process_request(struct optee_private *priv, void *req,
>  		mmc = get_mmc(priv, sreq->dev_id);
>  		if (!mmc)
>  			return TEE_ERROR_ITEM_NOT_FOUND;
> -		if (mmc_rpmb_route_frames(mmc, RPMB_REQ_DATA(req),
> -					  req_size - sizeof(struct rpmb_req),
> -					  rsp, rsp_size))
> +
> +		rpmb_data = RPMB_REQ_DATA(req);
> +		rpmb_data_sz = req_size - sizeof(struct rpmb_req);
> +		if (!IS_ALIGNED((uintptr_t)rpmb_data, sizeof(u32))) {
> +			/* 32bit data alignment is required by RPMB driver */
> +			rpmb_frame_buffer = malloc(rpmb_data_sz);
> +			if (!rpmb_frame_buffer)
> +				return TEE_ERROR_OUT_OF_MEMORY;
> +
> +			memcpy(rpmb_frame_buffer, rpmb_data, rpmb_data_sz);
> +			rpmb_data = rpmb_frame_buffer;
> +		}
> +
> +		ret = mmc_rpmb_route_frames(mmc, rpmb_data, rpmb_data_sz,
> +					    rsp, rsp_size);
> +		free(rpmb_frame_buffer);
> +		if (ret)
>  			return TEE_ERROR_BAD_PARAMETERS;
>  		return TEE_SUCCESS;
>
> --
> 2.17.1
>
>