[PATCH] mmc: card: restrict access to RPMB partition

[Ulf Hansson]

On 9 May 2014 15:39, Yuvaraj Kumar C D <yuvaraj.cd at gmail.com> wrote:
> From: Andrew Bresticker <abrestic at chromium.org>
>
> The RPMB partition should only be accessed through the RPMB ioctls
> and not through read()/write().  This patch makes mmc_blk_open()
> reject open attempts to the RPMB partition in read or write mode.
>
> Signed-off-by: Andrew Bresticker <abrestic at chromium.org>
> Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd at samsung.com>
> ---
>  drivers/mmc/card/block.c |   10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 452782b..fd59090 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -297,7 +297,15 @@ static int mmc_blk_open(struct block_device *bdev, fmode_t mode)
>                         check_disk_change(bdev);
>                 ret = 0;
>
> -               if ((mode & FMODE_WRITE) && md->read_only) {
> +               /*
> +                * Reject read/write access to the RPMB partition.  It should
> +                * only be accessed through ioctls.
> +                */
> +               if ((mode & (FMODE_READ | FMODE_WRITE)) &&
> +                   md->area_type & MMC_BLK_DATA_AREA_RPMB) {
> +                       mmc_blk_put(md);
> +                       ret = -EACCES;

How shall user space be able to receive a file descriptor, unless it's
allowed to open the device?

Kind regards
Ulf Hansson