RE: [PATCHv3 1/1] mmc: block: ioctl: Add PROG-error aggregation

[Avri Altman]

> Userspace currently has no way of checking for error bits of
> detection mode X. These are error bits that are only detected by
> the card when executing the command. For e.g. a sanitize operation
> this may be minutes after the RSP was seen by the host.
> 
> Currently userspace programs cannot see these error bits reliably.
> They could issue a multi ioctl cmd with a CMD13 immediately following
> it, but since errors of detection mode X are automatically cleared
> (they are all clear condition B).
> mmc_poll_for_busy of the first ioctl may have already hidden such an
> error flag.
> 
> In case of the security operations: sanitize, secure erases and
> RPMB writes, this could lead to the operation not being performed
> successfully by the card with the user not knowing.
> If the user trusts that this operation is completed
> (e.g. their data is sanitized), this could be a security issue.
> An attacker could e.g. provoke a eMMC (VCC) flash fail, where a
> successful sanitize of a card is not possible. A card may move out
> of PROG state but issue a bit 19 R1 error.
> 
> This patch therefore will also have the consequence of a mmc-utils
> patch, which enables the bit for the security-sensitive operations.
> 
> Signed-off-by: Christian Loehle <cloehle@xxxxxxxxxxxxxx>
Acked-by: Avri Altman <avri.altman@xxxxxxx>

> ---
>  drivers/mmc/core/block.c   | 26 +++++++++++++++-----------
>  drivers/mmc/core/mmc_ops.c | 14 +++++++-------
>  drivers/mmc/core/mmc_ops.h |  9 +++++++++
>  3 files changed, 31 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index e46330815484..c7e2b8ae58a9 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -470,7 +470,7 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card
> *card, struct mmc_blk_data *md,
>  	struct mmc_data data = {};
>  	struct mmc_request mrq = {};
>  	struct scatterlist sg;
> -	bool r1b_resp, use_r1b_resp = false;
> +	bool r1b_resp;
>  	unsigned int busy_timeout_ms;
>  	int err;
>  	unsigned int target_part;
> @@ -551,8 +551,7 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card
> *card, struct mmc_blk_data *md,
>  	busy_timeout_ms = idata->ic.cmd_timeout_ms ? :
> MMC_BLK_TIMEOUT_MS;
>  	r1b_resp = (cmd.flags & MMC_RSP_R1B) == MMC_RSP_R1B;
>  	if (r1b_resp)
> -		use_r1b_resp = mmc_prepare_busy_cmd(card->host, &cmd,
> -						    busy_timeout_ms);
> +		mmc_prepare_busy_cmd(card->host, &cmd,
> busy_timeout_ms);
> 
>  	mmc_wait_for_req(card->host, &mrq);
>  	memcpy(&idata->ic.response, cmd.resp, sizeof(cmd.resp));
> @@ -605,19 +604,24 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card
> *card, struct mmc_blk_data *md,
>  	if (idata->ic.postsleep_min_us)
>  		usleep_range(idata->ic.postsleep_min_us, idata-
> >ic.postsleep_max_us);
> 
> -	/* No need to poll when using HW busy detection. */
> -	if ((card->host->caps & MMC_CAP_WAIT_WHILE_BUSY) &&
> use_r1b_resp)
> -		return 0;
> -
>  	if (mmc_host_is_spi(card->host)) {
>  		if (idata->ic.write_flag || r1b_resp || cmd.flags &
> MMC_RSP_SPI_BUSY)
>  			return mmc_spi_err_check(card);
>  		return err;
>  	}
> -	/* Ensure RPMB/R1B command has completed by polling with CMD13.
> */
> -	if (idata->rpmb || r1b_resp)
> -		err = mmc_poll_for_busy(card, busy_timeout_ms, false,
> -					MMC_BUSY_IO);
> +	/* Poll for RPMB/write/R1B execution errors */
> +	if (idata->rpmb || idata->ic.write_flag || r1b_resp) {
AFAIK write_flag  and r1b_resp are set together (in mmc-utils that is)?
As for rpmb read operations you were pondering about -
the rpmb read-counter is one example, because you use it to sign write operations.
So restoring all rpmb operations is in place - all should be monitored.

> +		struct mmc_busy_data cb_data;
Maybe use designated initializing?

Thanks,
Avri
> +
> +		cb_data.card = card;
> +		cb_data.retry_crc_err = false;
> +		cb_data.aggregate_err_flags = true;
> +		cb_data.busy_cmd = MMC_BUSY_IO;
> +		cb_data.status = &idata->ic.response[0];
> +		err = __mmc_poll_for_busy(card->host, 0, busy_timeout_ms,
> +				&mmc_busy_cb, &cb_data);
> +
> +	}
> 
>  	return err;
>  }
> diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
> index 3b3adbddf664..15d8b806c670 100644
> --- a/drivers/mmc/core/mmc_ops.c
> +++ b/drivers/mmc/core/mmc_ops.c
> @@ -54,11 +54,6 @@ static const u8 tuning_blk_pattern_8bit[] = {
>  	0xff, 0x77, 0x77, 0xff, 0x77, 0xbb, 0xdd, 0xee,
>  };
> 
> -struct mmc_busy_data {
> -	struct mmc_card *card;
> -	bool retry_crc_err;
> -	enum mmc_busy_cmd busy_cmd;
> -};
> 
>  struct mmc_op_cond_busy_data {
>  	struct mmc_host *host;
> @@ -457,14 +452,15 @@ int mmc_switch_status(struct mmc_card *card, bool
> crc_err_fatal)
>  	return mmc_switch_status_error(card->host, status);
>  }
> 
> -static int mmc_busy_cb(void *cb_data, bool *busy)
> +int mmc_busy_cb(void *cb_data, bool *busy)
>  {
>  	struct mmc_busy_data *data = cb_data;
>  	struct mmc_host *host = data->card->host;
>  	u32 status = 0;
>  	int err;
> 
> -	if (data->busy_cmd != MMC_BUSY_IO && host->ops->card_busy) {
> +	if (data->busy_cmd != MMC_BUSY_IO && host->ops->card_busy &&
> +			!data->aggregate_err_flags) {
>  		*busy = host->ops->card_busy(host);
>  		return 0;
>  	}
> @@ -477,6 +473,9 @@ static int mmc_busy_cb(void *cb_data, bool *busy)
>  	if (err)
>  		return err;
> 
> +	if (data->aggregate_err_flags)
> +		*data->status = R1_STATUS(*data->status) | status;
> +
>  	switch (data->busy_cmd) {
>  	case MMC_BUSY_CMD6:
>  		err = mmc_switch_status_error(host, status);
> @@ -549,6 +548,7 @@ int mmc_poll_for_busy(struct mmc_card *card,
> unsigned int timeout_ms,
> 
>  	cb_data.card = card;
>  	cb_data.retry_crc_err = retry_crc_err;
> +	cb_data.aggregate_err_flags = false;
>  	cb_data.busy_cmd = busy_cmd;
> 
>  	return __mmc_poll_for_busy(host, 0, timeout_ms, &mmc_busy_cb,
> &cb_data);
> diff --git a/drivers/mmc/core/mmc_ops.h b/drivers/mmc/core/mmc_ops.h
> index 09ffbc00908b..a57751b83f19 100644
> --- a/drivers/mmc/core/mmc_ops.h
> +++ b/drivers/mmc/core/mmc_ops.h
> @@ -18,6 +18,14 @@ enum mmc_busy_cmd {
>  	MMC_BUSY_IO,
>  };
> 
> +struct mmc_busy_data {
> +	struct mmc_card *card;
> +	bool retry_crc_err;
> +	bool aggregate_err_flags;
> +	enum mmc_busy_cmd busy_cmd;
> +	u32 *status;
> +};
> +
>  struct mmc_host;
>  struct mmc_card;
>  struct mmc_command;
> @@ -41,6 +49,7 @@ int mmc_can_ext_csd(struct mmc_card *card);
>  int mmc_switch_status(struct mmc_card *card, bool crc_err_fatal);
>  bool mmc_prepare_busy_cmd(struct mmc_host *host, struct mmc_command
> *cmd,
>  			  unsigned int timeout_ms);
> +int mmc_busy_cb(void *cb_data, bool *busy);
>  int __mmc_poll_for_busy(struct mmc_host *host, unsigned int period_us,
>  			unsigned int timeout_ms,
>  			int (*busy_cb)(void *cb_data, bool *busy),
> --
> 2.37.3