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Date: Thu, 8 Jun 2023 17:23:13 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Christian Loehle <CLoehle@...erstone.com>
Cc: "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Avri Altman <avri.altman@....com>
Subject: Re: [PATCHv2 2/2] mmc: block: ioctl: Add PROG-error aggregation
On Thu, 25 May 2023 at 11:56, Christian Loehle <CLoehle@...erstone.com> wrote:
>
> 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@...erstone.com>
> ---
> drivers/mmc/core/block.c | 17 ++++++-----------
> drivers/mmc/core/mmc_ops.c | 25 ++++++++++++++++++++++++-
> drivers/mmc/core/mmc_ops.h | 3 +++
> 3 files changed, 33 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index e46330815484..44c1b2825032 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 +604,15 @@ 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 write/R1B execution errors */
> + if (idata->ic.write_flag || r1b_resp)
Earlier we polled for requests that were targeted to rpmb, no matter
if they were write or reads. Are you intentionally changing this? If
so, can you explain why?
> + err = mmc_poll_for_busy_err_flags(card, busy_timeout_ms, false,
> + MMC_BUSY_IO, &idata->ic.response[0]);
I think it's better to extend the mmc_blk_busy_cb, rather than
introducing an entirely new polling function.
Then you can call __mmc_poll_for_busy() here instead.
>
> return err;
> }
> diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
> index 3b3adbddf664..11e566ab719c 100644
> --- a/drivers/mmc/core/mmc_ops.c
> +++ b/drivers/mmc/core/mmc_ops.c
> @@ -57,7 +57,9 @@ static const u8 tuning_blk_pattern_8bit[] = {
> 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_op_cond_busy_data {
> @@ -464,7 +466,8 @@ static int mmc_busy_cb(void *cb_data, bool *busy)
> 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 +480,9 @@ 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);
> @@ -549,12 +555,29 @@ 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);
> }
> EXPORT_SYMBOL_GPL(mmc_poll_for_busy);
>
> +int mmc_poll_for_busy_err_flags(struct mmc_card *card, unsigned int timeout_ms,
> + bool retry_crc_err, enum mmc_busy_cmd busy_cmd, u32 *status)
> +{
> + struct mmc_host *host = card->host;
> + struct mmc_busy_data cb_data;
> +
> + cb_data.card = card;
> + cb_data.retry_crc_err = retry_crc_err;
> + cb_data.aggregate_err_flags = true;
> + cb_data.busy_cmd = busy_cmd;
> + cb_data.status = status;
> +
> + return __mmc_poll_for_busy(host, 0, timeout_ms, &mmc_busy_cb, &cb_data);
> +}
> +EXPORT_SYMBOL_GPL(mmc_poll_for_busy_err_flags);
> +
> bool mmc_prepare_busy_cmd(struct mmc_host *host, struct mmc_command *cmd,
> unsigned int timeout_ms)
> {
> diff --git a/drivers/mmc/core/mmc_ops.h b/drivers/mmc/core/mmc_ops.h
> index 09ffbc00908b..fc7ec43a78dc 100644
> --- a/drivers/mmc/core/mmc_ops.h
> +++ b/drivers/mmc/core/mmc_ops.h
> @@ -47,6 +47,9 @@ int __mmc_poll_for_busy(struct mmc_host *host, unsigned int period_us,
> void *cb_data);
> int mmc_poll_for_busy(struct mmc_card *card, unsigned int timeout_ms,
> bool retry_crc_err, enum mmc_busy_cmd busy_cmd);
> +int mmc_poll_for_busy_err_flags(struct mmc_card *card, unsigned int timeout_ms,
> + bool retry_crc_err, enum mmc_busy_cmd busy_cmd,
> + u32 *status);
> int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
> unsigned int timeout_ms, unsigned char timing,
> bool send_status, bool retry_crc_err, unsigned int retries);
> --
Kind regards
Uffe
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