RE: [PATCH v4] mmc: core: Use mrq.sbc in close-ended ffu

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> On Thu, Nov 30, 2023 at 11:36:10AM +0100, Ulf Hansson wrote:
> > On Wed, 29 Nov 2023 at 10:25, Avri Altman <avri.altman@xxxxxxx> wrote:
> > >
> > > Field Firmware Update (ffu) may use close-ended or open ended sequence.
> > > Each such sequence is comprised of a write commands enclosed between
> > > 2 switch commands - to and from ffu mode. So for the close-ended
> > > case, it will be: cmd6->cmd23-cmd25-cmd6.
> > >
> > > Some host controllers however, get confused when multi-block rw is
> > > sent without sbc, and may generate auto-cmd12 which breaks the ffu
> sequence.
> > > I encountered  this issue while testing fwupd
> > > (github.com/fwupd/fwupd) on HP Chromebook x2, a qualcomm based QC-
> 7c, code name - strongbad.
> > >
> > > Instead of a quirk, or hooking the request function of the msm ops,
> > > it would be better to fix the ioctl handling and make it use mrq.sbc
> > > instead of issuing SET_BLOCK_COUNT separately.
> > >
> > > Signed-off-by: Avri Altman <avri.altman@xxxxxxx>
> >
> > Applied for next (to get it tested a bit more) and by adding a stable
> > tag, thanks!
> 
> This change is causing RPMB breakage in 6.6.13 and also 6.6.20. rockpi4b and
> synquacer arm64 boards with u-boot, optee 4.1.0 and firmware TPM (fTPM) fail
> to access RPMB via kernel and tee-supplicant 4.1.0.
> 
> More details in https://bugzilla.kernel.org/show_bug.cgi?id=218587
> 
> I've tried to identify what exactly is going wrong but failed so far. Reverting this
> changes is the only working solution so far. This also triggered a kernel crash on
> error path https://bugzilla.kernel.org/show_bug.cgi?id=218542 which is now
> fixed/queued.
> 
> If you have any hints how to debug this further or patches to try, I'd be happy to
> try those out.
I don't know nothing about tpm nor the ftpm.
The above patch is scanning command sequences sent via MMC_IOC_MULTI_CMD,
looking for pairs of CMD23->CMD25 or CMD23->CMD18,
drops the CMD23 and build one instead in __mmc_blk_ioctl_cmd as the mrq.sbc.
AFAIK user-space utils, e.g. mmc-utils count on the mmc driver to provide SBC when accessing rpmb,
so their multi-ioctl sequences does not include CMD23, hence does not affected by this code.

Looking in the strace included, I tried to find where MMC_IOC_MULTI_CMD is sent.
There are 8 such ioctl calls.
I guess the tee supplicant sources are unavailable,
But it looks like 2 simultaneous threads are trying to access the rpmb partition - which is forbidden.
Opening /dev/mmcblk0rpmb from user space is exclusive, so I am not sure how even this is possible.

I can try and help you debug this - you can contact me offline.

Thanks,
Avri

> 
> Cheers,
> 
> -Mikko
> 
> > Kind regards
> > Uffe
> >
> >
> > > ---
> > >
> > > Changelog:
> > > v3--v4:
> > >         check sbc.error as well
> > > v2--v3:
> > >         Adopt Adrian's proposal
> > > v1--v2:
> > >         remove redundant reference of reliable write
> > > ---
> > >  drivers/mmc/core/block.c | 46
> > > +++++++++++++++++++++++++++++++++++++---
> > >  1 file changed, 43 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> > > index f9a5cffa64b1..892e74e611a0 100644
> > > --- a/drivers/mmc/core/block.c
> > > +++ b/drivers/mmc/core/block.c
> > > @@ -400,6 +400,10 @@ struct mmc_blk_ioc_data {
> > >         struct mmc_ioc_cmd ic;
> > >         unsigned char *buf;
> > >         u64 buf_bytes;
> > > +       unsigned int flags;
> > > +#define MMC_BLK_IOC_DROP       BIT(0)  /* drop this mrq */
> > > +#define MMC_BLK_IOC_SBC        BIT(1)  /* use mrq.sbc */
> > > +
> > >         struct mmc_rpmb_data *rpmb;
> > >  };
> > >
> > > @@ -465,7 +469,7 @@ static int mmc_blk_ioctl_copy_to_user(struct
> > > mmc_ioc_cmd __user *ic_ptr,  }
> > >
> > >  static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct
> mmc_blk_data *md,
> > > -                              struct mmc_blk_ioc_data *idata)
> > > +                              struct mmc_blk_ioc_data **idatas, int
> > > + i)
> > >  {
> > >         struct mmc_command cmd = {}, sbc = {};
> > >         struct mmc_data data = {};
> > > @@ -475,10 +479,18 @@ static int __mmc_blk_ioctl_cmd(struct
> mmc_card *card, struct mmc_blk_data *md,
> > >         unsigned int busy_timeout_ms;
> > >         int err;
> > >         unsigned int target_part;
> > > +       struct mmc_blk_ioc_data *idata = idatas[i];
> > > +       struct mmc_blk_ioc_data *prev_idata = NULL;
> > >
> > >         if (!card || !md || !idata)
> > >                 return -EINVAL;
> > >
> > > +       if (idata->flags & MMC_BLK_IOC_DROP)
> > > +               return 0;
> > > +
> > > +       if (idata->flags & MMC_BLK_IOC_SBC)
> > > +               prev_idata = idatas[i - 1];
> > > +
> > >         /*
> > >          * The RPMB accesses comes in from the character device, so we
> > >          * need to target these explicitly. Else we just target the
> > > @@ -532,7 +544,7 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card
> *card, struct mmc_blk_data *md,
> > >                         return err;
> > >         }
> > >
> > > -       if (idata->rpmb) {
> > > +       if (idata->rpmb || prev_idata) {
> > >                 sbc.opcode = MMC_SET_BLOCK_COUNT;
> > >                 /*
> > >                  * We don't do any blockcount validation because the
> > > max size @@ -540,6 +552,8 @@ static int __mmc_blk_ioctl_cmd(struct
> mmc_card *card, struct mmc_blk_data *md,
> > >                  * 'Reliable Write' bit here.
> > >                  */
> > >                 sbc.arg = data.blocks | (idata->ic.write_flag &
> > > BIT(31));
> > > +               if (prev_idata)
> > > +                       sbc.arg = prev_idata->ic.arg;
> > >                 sbc.flags = MMC_RSP_R1 | MMC_CMD_AC;
> > >                 mrq.sbc = &sbc;
> > >         }
> > > @@ -557,6 +571,15 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card
> *card, struct mmc_blk_data *md,
> > >         mmc_wait_for_req(card->host, &mrq);
> > >         memcpy(&idata->ic.response, cmd.resp, sizeof(cmd.resp));
> > >
> > > +       if (prev_idata) {
> > > +               memcpy(&prev_idata->ic.response, sbc.resp, sizeof(sbc.resp));
> > > +               if (sbc.error) {
> > > +                       dev_err(mmc_dev(card->host), "%s: sbc error %d\n",
> > > +                                                       __func__, sbc.error);
> > > +                       return sbc.error;
> > > +               }
> > > +       }
> > > +
> > >         if (cmd.error) {
> > >                 dev_err(mmc_dev(card->host), "%s: cmd error %d\n",
> > >                                                 __func__,
> > > cmd.error); @@ -1032,6 +1055,20 @@ static inline void
> mmc_blk_reset_success(struct mmc_blk_data *md, int type)
> > >         md->reset_done &= ~type;
> > >  }
> > >
> > > +static void mmc_blk_check_sbc(struct mmc_queue_req *mq_rq) {
> > > +       struct mmc_blk_ioc_data **idata = mq_rq->drv_op_data;
> > > +       int i;
> > > +
> > > +       for (i = 1; i < mq_rq->ioc_count; i++) {
> > > +               if (idata[i - 1]->ic.opcode == MMC_SET_BLOCK_COUNT &&
> > > +                   mmc_op_multi(idata[i]->ic.opcode)) {
> > > +                       idata[i - 1]->flags |= MMC_BLK_IOC_DROP;
> > > +                       idata[i]->flags |= MMC_BLK_IOC_SBC;
> > > +               }
> > > +       }
> > > +}
> > > +
> > >  /*
> > >   * The non-block commands come back from the block layer after it queued
> it and
> > >   * processed it with all other requests and then they get issued in
> > > this @@ -1059,11 +1096,14 @@ static void mmc_blk_issue_drv_op(struct
> mmc_queue *mq, struct request *req)
> > >                         if (ret)
> > >                                 break;
> > >                 }
> > > +
> > > +               mmc_blk_check_sbc(mq_rq);
> > > +
> > >                 fallthrough;
> > >         case MMC_DRV_OP_IOCTL_RPMB:
> > >                 idata = mq_rq->drv_op_data;
> > >                 for (i = 0, ret = 0; i < mq_rq->ioc_count; i++) {
> > > -                       ret = __mmc_blk_ioctl_cmd(card, md, idata[i]);
> > > +                       ret = __mmc_blk_ioctl_cmd(card, md, idata,
> > > + i);
> > >                         if (ret)
> > >                                 break;
> > >                 }
> > > --
> > > 2.42.0
> > >





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