linux-kernel - Re: [PATCHv3 1/1] mmc: block: ioctl: Add PROG-error aggregation

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Date:   Thu, 29 Jun 2023 16:54:21 +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: [PATCHv3 1/1] mmc: block: ioctl: Add PROG-error aggregation

On Wed, 28 Jun 2023 at 08:47, Christian Loehle <CLoehle@...erstone.com> wrote:
>
>
>
> > -----Original Message-----
> > From: Ulf Hansson <ulf.hansson@...aro.org>
> > Sent: Donnerstag, 22. Juni 2023 11:46
> > To: Christian Loehle <CLoehle@...erstone.com>
> > Cc: linux-mmc@...r.kernel.org; linux-kernel@...r.kernel.org; Adrian
> > Hunter <adrian.hunter@...el.com>; Avri Altman <avri.altman@....com>
> > Subject: Re: [PATCHv3 1/1] mmc: block: ioctl: Add PROG-error aggregation
> >
> > CAUTION: this mail comes from external!/ACHTUNG: Diese Mail kommt von
> > extern!
> >
> > On Tue, 20 Jun 2023 at 14:44, 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   | 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 */
> >
> > Except for the other comments that I had on v2 (which isn't addressed in v3),
> > I would like this comment to be extended a bit.
> Sorry, could you elaborate on the comments I haven't addressed?
> What I sent as v3 was what I understood from your comments.

No problem, it's probably me that was not clear enough.

Anyway, to help mode this forward, let me amend the patch and submit a
new version of it. Then you can have a look and confirm that it looks
good to you.

[...]

Kind regards
Uffe