[v10,09/15] FWU: Add boot time checks as highlighted by the FWU specification

The FWU Multi Bank Update specification requires the Update Agent to
carry out certain checks at the time of platform boot. The Update
Agent is the component which is responsible for updating the firmware
components and maintaining and keeping the metadata in sync.

The spec requires that the Update Agent perform the following checks
at the time of boot
* Sanity check of both the metadata copies maintained by the platform.
* Get the boot index passed to U-Boot by the prior stage bootloader
  and use this value for metadata bookkeeping.
* Check if the system is booting in Trial State. If the system boots
  in the Trial State for more than a specified number of boot counts,
  change the Active Bank to be booting the platform from.

Call these checks through the main loop event at the time of platform
boot.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
---
Changes since V9:
* Remove the unused variable active_idx, as suggested by Etienne

 include/fwu.h              |  13 +++
 lib/efi_loader/efi_setup.c |   1 +
 lib/fwu_updates/fwu.c      | 192 ++++++++++++++++++++++++++++++++++++-
 3 files changed, 204 insertions(+), 2 deletions(-)

On Thu, Sep 15, 2022 at 3:17 AM Sughosh Ganu <sughosh.ganu@linaro.org> wrote:

....
> diff --git a/include/fwu.h b/include/fwu.h
> index 484289ed4f..d5f77ce83c 100644
> --- a/include/fwu.h
> +++ b/include/fwu.h
> @@ -256,4 +256,17 @@ int fwu_plat_get_update_index(uint *update_idx);
>   *
>   */
>  void fwu_plat_get_bootidx(uint *boot_idx);
>
Or simply return the boot_idx instead of modifying the pointed variable

.....
> diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
> index c633fcd91e..557e97de4a 100644
> --- a/lib/efi_loader/efi_setup.c
> +++ b/lib/efi_loader/efi_setup.c
> @@ -199,6 +199,7 @@ static efi_status_t __efi_init_early(void)
>                 goto out;
>
>         ret = efi_disk_init();
> +
>  out:
>         return ret;
>  }
We can do without this change in this patchset :)


.....
> +static int fwu_trial_state_check(struct udevice *dev)
> +{
> +       int ret;
> +       efi_status_t status;
> +       efi_uintn_t var_size;
> +       u16 trial_state_ctr;
> +       u32 var_attributes;
> +       struct fwu_mdata mdata = { 0 };
> +
> +       ret = fwu_get_mdata(dev, &mdata);
> +       if (ret)
> +               return ret;
> +
> +       if ((trial_state = in_trial_state(&mdata))) {
>
This may raise warnings on code checkers. So maybe move the assignment
out of the check.


.....
> +static int fwu_boottime_checks(void *ctx, struct event *event)
> +{
> +       int ret;
> +       struct udevice *dev;
> +       u32 boot_idx, active_idx;
> +
> +       ret = fwu_get_dev_mdata(&dev, NULL);
> +       if (ret)
> +               return ret;
> +
> +       ret = fwu_mdata_check(dev);
> +       if (ret) {
> +               return 0;
> +       }
> +
> +       /*
> +        * Get the Boot Index, i.e. the bank from
> +        * which the platform has booted. This value
> +        * gets passed from the ealier stage bootloader
> +        * which booted u-boot, e.g. tf-a. If the
> +        * boot index is not the same as the
> +        * active_index read from the FWU metadata,
> +        * update the active_index.
> +        */
> +       fwu_plat_get_bootidx(&boot_idx);
> +       if (boot_idx >= CONFIG_FWU_NUM_BANKS) {
> +               log_err("Received incorrect value of boot_index\n");
> +               return 0;
> +       }
> +
> +       ret = fwu_get_active_index(&active_idx);
> +       if (ret) {
> +               log_err("Unable to read active_index\n");
> +               return 0;
> +       }
> +
> +       if (boot_idx != active_idx) {
> +               log_info("Boot idx %u is not matching active idx %u, changing active_idx\n",
> +                        boot_idx, active_idx);
> +               ret = fwu_update_active_index(boot_idx);
> +               if (!ret)
> +                       boottime_check = 1;
>
We may not want to do anything FWU (accept, reject, modify mdata)
until we reboot, if we are recovering from last bad upgrade. So maybe
not set boottime_check


cheers

On Mon, 26 Sept 2022 at 08:29, Jassi Brar <jassisinghbrar@gmail.com> wrote:
>
> On Thu, Sep 15, 2022 at 3:17 AM Sughosh Ganu <sughosh.ganu@linaro.org> wrote:
>
> ....
> > diff --git a/include/fwu.h b/include/fwu.h
> > index 484289ed4f..d5f77ce83c 100644
> > --- a/include/fwu.h
> > +++ b/include/fwu.h
> > @@ -256,4 +256,17 @@ int fwu_plat_get_update_index(uint *update_idx);
> >   *
> >   */
> >  void fwu_plat_get_bootidx(uint *boot_idx);
> >
> Or simply return the boot_idx instead of modifying the pointed variable

This is following the prototype that is being used for all the
functions. Would prefer to have that consistency.

>
> .....
> > diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
> > index c633fcd91e..557e97de4a 100644
> > --- a/lib/efi_loader/efi_setup.c
> > +++ b/lib/efi_loader/efi_setup.c
> > @@ -199,6 +199,7 @@ static efi_status_t __efi_init_early(void)
> >                 goto out;
> >
> >         ret = efi_disk_init();
> > +
> >  out:
> >         return ret;
> >  }
> We can do without this change in this patchset :)

Will remove.

>
>
> .....
> > +static int fwu_trial_state_check(struct udevice *dev)
> > +{
> > +       int ret;
> > +       efi_status_t status;
> > +       efi_uintn_t var_size;
> > +       u16 trial_state_ctr;
> > +       u32 var_attributes;
> > +       struct fwu_mdata mdata = { 0 };
> > +
> > +       ret = fwu_get_mdata(dev, &mdata);
> > +       if (ret)
> > +               return ret;
> > +
> > +       if ((trial_state = in_trial_state(&mdata))) {
> >
> This may raise warnings on code checkers. So maybe move the assignment
> out of the check.

I did get a compiler warning asking me to use the parentheses around
the assignment. But I can move the assignment out.

>
>
> .....
> > +static int fwu_boottime_checks(void *ctx, struct event *event)
> > +{
> > +       int ret;
> > +       struct udevice *dev;
> > +       u32 boot_idx, active_idx;
> > +
> > +       ret = fwu_get_dev_mdata(&dev, NULL);
> > +       if (ret)
> > +               return ret;
> > +
> > +       ret = fwu_mdata_check(dev);
> > +       if (ret) {
> > +               return 0;
> > +       }
> > +
> > +       /*
> > +        * Get the Boot Index, i.e. the bank from
> > +        * which the platform has booted. This value
> > +        * gets passed from the ealier stage bootloader
> > +        * which booted u-boot, e.g. tf-a. If the
> > +        * boot index is not the same as the
> > +        * active_index read from the FWU metadata,
> > +        * update the active_index.
> > +        */
> > +       fwu_plat_get_bootidx(&boot_idx);
> > +       if (boot_idx >= CONFIG_FWU_NUM_BANKS) {
> > +               log_err("Received incorrect value of boot_index\n");
> > +               return 0;
> > +       }
> > +
> > +       ret = fwu_get_active_index(&active_idx);
> > +       if (ret) {
> > +               log_err("Unable to read active_index\n");
> > +               return 0;
> > +       }
> > +
> > +       if (boot_idx != active_idx) {
> > +               log_info("Boot idx %u is not matching active idx %u, changing active_idx\n",
> > +                        boot_idx, active_idx);
> > +               ret = fwu_update_active_index(boot_idx);
> > +               if (!ret)
> > +                       boottime_check = 1;
> >
> We may not want to do anything FWU (accept, reject, modify mdata)
> until we reboot, if we are recovering from last bad upgrade. So maybe
> not set boottime_check

Actually, the difference between the boot bank and active bank will
happen when there is some kind of corruption on the media due to which
the platform could not boot from the active bank(could also be due to
repeated wd timeouts). What issue do you see in attempting to update
the other bank in case of a mismatch.

-sughosh

On Mon, Sep 26, 2022 at 5:08 AM Sughosh Ganu <sughosh.ganu@linaro.org> wrote:
>
> On Mon, 26 Sept 2022 at 08:29, Jassi Brar <jassisinghbrar@gmail.com> wrote:
> > .....
> > > +static int fwu_boottime_checks(void *ctx, struct event *event)
> > > +{
> > > +       int ret;
> > > +       struct udevice *dev;
> > > +       u32 boot_idx, active_idx;
> > > +
> > > +       ret = fwu_get_dev_mdata(&dev, NULL);
> > > +       if (ret)
> > > +               return ret;
> > > +
> > > +       ret = fwu_mdata_check(dev);
> > > +       if (ret) {
> > > +               return 0;
> > > +       }
> > > +
> > > +       /*
> > > +        * Get the Boot Index, i.e. the bank from
> > > +        * which the platform has booted. This value
> > > +        * gets passed from the ealier stage bootloader
> > > +        * which booted u-boot, e.g. tf-a. If the
> > > +        * boot index is not the same as the
> > > +        * active_index read from the FWU metadata,
> > > +        * update the active_index.
> > > +        */
> > > +       fwu_plat_get_bootidx(&boot_idx);
> > > +       if (boot_idx >= CONFIG_FWU_NUM_BANKS) {
> > > +               log_err("Received incorrect value of boot_index\n");
> > > +               return 0;
> > > +       }
> > > +
> > > +       ret = fwu_get_active_index(&active_idx);
> > > +       if (ret) {
> > > +               log_err("Unable to read active_index\n");
> > > +               return 0;
> > > +       }
> > > +
> > > +       if (boot_idx != active_idx) {
> > > +               log_info("Boot idx %u is not matching active idx %u, changing active_idx\n",
> > > +                        boot_idx, active_idx);
> > > +               ret = fwu_update_active_index(boot_idx);
> > > +               if (!ret)
> > > +                       boottime_check = 1;
> > >
> > We may not want to do anything FWU (accept, reject, modify mdata)
> > until we reboot, if we are recovering from last bad upgrade. So maybe
> > not set boottime_check
>
> Actually, the difference between the boot bank and active bank will
> happen when there is some kind of corruption on the media due to which
> the platform could not boot from the active bank(could also be due to
> repeated wd timeouts).
>
... which may have been caused by the last upgrade attempt, among other reasons.

fwu_trial_state_check() will never be called in this case and any
subsequent fwu_update_checks_pass() will pass even if we are in trial
state.

-j

On Mon, 26 Sept 2022 at 19:37, Jassi Brar <jassisinghbrar@gmail.com> wrote:
>
> On Mon, Sep 26, 2022 at 5:08 AM Sughosh Ganu <sughosh.ganu@linaro.org> wrote:
> >
> > On Mon, 26 Sept 2022 at 08:29, Jassi Brar <jassisinghbrar@gmail.com> wrote:
> > > .....
> > > > +static int fwu_boottime_checks(void *ctx, struct event *event)
> > > > +{
> > > > +       int ret;
> > > > +       struct udevice *dev;
> > > > +       u32 boot_idx, active_idx;
> > > > +
> > > > +       ret = fwu_get_dev_mdata(&dev, NULL);
> > > > +       if (ret)
> > > > +               return ret;
> > > > +
> > > > +       ret = fwu_mdata_check(dev);
> > > > +       if (ret) {
> > > > +               return 0;
> > > > +       }
> > > > +
> > > > +       /*
> > > > +        * Get the Boot Index, i.e. the bank from
> > > > +        * which the platform has booted. This value
> > > > +        * gets passed from the ealier stage bootloader
> > > > +        * which booted u-boot, e.g. tf-a. If the
> > > > +        * boot index is not the same as the
> > > > +        * active_index read from the FWU metadata,
> > > > +        * update the active_index.
> > > > +        */
> > > > +       fwu_plat_get_bootidx(&boot_idx);
> > > > +       if (boot_idx >= CONFIG_FWU_NUM_BANKS) {
> > > > +               log_err("Received incorrect value of boot_index\n");
> > > > +               return 0;
> > > > +       }
> > > > +
> > > > +       ret = fwu_get_active_index(&active_idx);
> > > > +       if (ret) {
> > > > +               log_err("Unable to read active_index\n");
> > > > +               return 0;
> > > > +       }
> > > > +
> > > > +       if (boot_idx != active_idx) {
> > > > +               log_info("Boot idx %u is not matching active idx %u, changing active_idx\n",
> > > > +                        boot_idx, active_idx);
> > > > +               ret = fwu_update_active_index(boot_idx);
> > > > +               if (!ret)
> > > > +                       boottime_check = 1;
> > > >
> > > We may not want to do anything FWU (accept, reject, modify mdata)
> > > until we reboot, if we are recovering from last bad upgrade. So maybe
> > > not set boottime_check
> >
> > Actually, the difference between the boot bank and active bank will
> > happen when there is some kind of corruption on the media due to which
> > the platform could not boot from the active bank(could also be due to
> > repeated wd timeouts).
> >
> ... which may have been caused by the last upgrade attempt, among other reasons.
>
> fwu_trial_state_check() will never be called in this case and any
> subsequent fwu_update_checks_pass() will pass even if we are in trial
> state.

If the platform is unable to boot from the updated partition,
resulting in booting from a different partition, the platform is no
longer in the trial state, since it has not booted from the updated
partition -- determination of trial state is only based on reading the
accepted bit of all images in the booted partition. I believe this
would be a reason to want to change the images on the other partition
from which the platform could not boot, unless that was due to some
hardware error, in which case it would require manual intervention.
But my point is, not allowing FWU updates in the scenario you mention
does not help prevent any unwanted situation.

-sughosh