Re: [PATCH v4 3/5] efi_loader: add ExitBootServices() measurement

[Masahisa Kojima <masahisa.kojima@linaro.org>]

On Sat, 14 Aug 2021 at 18:06, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
>
> On 8/13/21 9:12 AM, Masahisa Kojima wrote:
> > TCG PC Client PFP spec requires to measure
> > "Exit Boot Services Invocation" if ExitBootServices() is invoked.
> > Depending upon the return code from the ExitBootServices() call,
> > "Exit Boot Services Returned with Success" or "Exit Boot Services
> > Returned with Failure" is also measured.
> >
> > Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
> > ---
> > Changes in v4:
> > - remove unnecessary EFIAPI specifier
> >
> > Changes in v2:
> > - use strlen instead of sizeof, event log for EV_EFI_ACTION string
> >
> >    shall not include NUL terminator
> >   include/efi_loader.h          |  1 +
> >   lib/efi_loader/efi_boottime.c |  5 +++
> >   lib/efi_loader/efi_tcg2.c     | 70 +++++++++++++++++++++++++++++++++++
> >   3 files changed, 76 insertions(+)
> >
> > diff --git a/include/efi_loader.h b/include/efi_loader.h
> > index 6f61e9faac..32cb8d0f1e 100644
> > --- a/include/efi_loader.h
> > +++ b/include/efi_loader.h
> > @@ -499,6 +499,7 @@ efi_status_t efi_run_image(void *source_buffer, efi_uintn_t source_size);
> >   efi_status_t efi_init_variables(void);
> >   /* Notify ExitBootServices() is called */
> >   void efi_variables_boot_exit_notify(void);
> > +efi_status_t efi_tcg2_notify_exit_boot_services_failed(void);
> >   /* Measure efi application invocation */
> >   efi_status_t efi_tcg2_measure_efi_app_invocation(void);
> >   /* Measure efi application exit */
> > diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
> > index 13ab139222..b818cbb540 100644
> > --- a/lib/efi_loader/efi_boottime.c
> > +++ b/lib/efi_loader/efi_boottime.c
> > @@ -2182,6 +2182,11 @@ static efi_status_t EFIAPI efi_exit_boot_services(efi_handle_t image_handle,
> >       efi_set_watchdog(0);
> >       WATCHDOG_RESET();
> >   out:
> > +     if (ret != EFI_SUCCESS) {
> > +             if (IS_ENABLED(CONFIG_EFI_TCG2_PROTOCOL))
> > +                     efi_tcg2_notify_exit_boot_services_failed();
> > +     }
> > +
> >       return EFI_EXIT(ret);
> >   }
> >
> > diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c
> > index ed71337780..8557fce1da 100644
> > --- a/lib/efi_loader/efi_tcg2.c
> > +++ b/lib/efi_loader/efi_tcg2.c
> > @@ -1506,6 +1506,67 @@ efi_status_t efi_tcg2_measure_efi_app_exit(void)
> >       return ret;
> >   }
> >
> > +/**
> > + * efi_tcg2_notify_exit_boot_services() - ExitBootService callback
> > + *
> > + * @event:   callback event
> > + * @context: callback context
> > + */
> > +static void
>
> Event notification functions must be of return type void EFIAPI to match
> the ABI used by the x86_64 in the UEFI API.
>
> I will fix this when merging.

Hi Heinrich,

Thank you for your fix and merging.

Regards,
Masahisa Kojima

>
> Best regards
>
> Heinrich
>
> > +efi_tcg2_notify_exit_boot_services(struct efi_event *event, void *context)
> > +{
> > +     efi_status_t ret;
> > +     struct udevice *dev;
> > +
> > +     EFI_ENTRY("%p, %p", event, context);
> > +
> > +     ret = platform_get_tpm2_device(&dev);
> > +     if (ret != EFI_SUCCESS)
> > +             goto out;
> > +
> > +     ret = tcg2_measure_event(dev, 5, EV_EFI_ACTION,
> > +                              strlen(EFI_EXIT_BOOT_SERVICES_INVOCATION),
> > +                              (u8 *)EFI_EXIT_BOOT_SERVICES_INVOCATION);
> > +     if (ret != EFI_SUCCESS)
> > +             goto out;
> > +
> > +     ret = tcg2_measure_event(dev, 5, EV_EFI_ACTION,
> > +                              strlen(EFI_EXIT_BOOT_SERVICES_SUCCEEDED),
> > +                              (u8 *)EFI_EXIT_BOOT_SERVICES_SUCCEEDED);
> > +
> > +out:
> > +     EFI_EXIT(ret);
> > +}
> > +
> > +/**
> > + * efi_tcg2_notify_exit_boot_services_failed()
> > + *  - notify ExitBootServices() is failed
> > + *
> > + * Return:   status code
> > + */
> > +efi_status_t efi_tcg2_notify_exit_boot_services_failed(void)
> > +{
> > +     struct udevice *dev;
> > +     efi_status_t ret;
> > +
> > +     ret = platform_get_tpm2_device(&dev);
> > +     if (ret != EFI_SUCCESS)
> > +             goto out;
> > +
> > +     ret = tcg2_measure_event(dev, 5, EV_EFI_ACTION,
> > +                              strlen(EFI_EXIT_BOOT_SERVICES_INVOCATION),
> > +                              (u8 *)EFI_EXIT_BOOT_SERVICES_INVOCATION);
> > +     if (ret != EFI_SUCCESS)
> > +             goto out;
> > +
> > +     ret = tcg2_measure_event(dev, 5, EV_EFI_ACTION,
> > +                              strlen(EFI_EXIT_BOOT_SERVICES_FAILED),
> > +                              (u8 *)EFI_EXIT_BOOT_SERVICES_FAILED);
> > +
> > +out:
> > +     return ret;
> > +}
> > +
> >   /**
> >    * tcg2_measure_secure_boot_variable() - measure secure boot variables
> >    *
> > @@ -1584,6 +1645,7 @@ efi_status_t efi_tcg2_register(void)
> >   {
> >       efi_status_t ret = EFI_SUCCESS;
> >       struct udevice *dev;
> > +     struct efi_event *event;
> >
> >       ret = platform_get_tpm2_device(&dev);
> >       if (ret != EFI_SUCCESS) {
> > @@ -1608,6 +1670,14 @@ efi_status_t efi_tcg2_register(void)
> >               goto fail;
> >       }
> >
> > +     ret = efi_create_event(EVT_SIGNAL_EXIT_BOOT_SERVICES, TPL_CALLBACK,
> > +                            efi_tcg2_notify_exit_boot_services, NULL,
> > +                            NULL, &event);
> > +     if (ret != EFI_SUCCESS) {
> > +             tcg2_uninit();
> > +             goto fail;
> > +     }
> > +
> >       ret = tcg2_measure_secure_boot_variable(dev);
> >       if (ret != EFI_SUCCESS) {
> >               tcg2_uninit();
> >
>