Re: [PATCH v2 22/22] ieee1275: enter lockdown based on /ibm,secure-boot

[Stefan Berger]

On 6/30/21 4:40 AM, Daniel Axtens wrote:
> If the 'ibm,secure-boot' property of the root node is 2 or greater,
> enter lockdown.
>
> Signed-off-by: Daniel Axtens <dja@axtens.net>

Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>


> ---
>   docs/grub.texi                 |  4 ++--
>   grub-core/Makefile.core.def    |  1 +
>   grub-core/kern/ieee1275/init.c | 27 +++++++++++++++++++++++++++
>   include/grub/lockdown.h        |  3 ++-
>   4 files changed, 32 insertions(+), 3 deletions(-)
>
> diff --git a/docs/grub.texi b/docs/grub.texi
> index 02fcda11e3bd..b13316cdb491 100644
> --- a/docs/grub.texi
> +++ b/docs/grub.texi
> @@ -6189,8 +6189,8 @@ Measured boot is currently only supported on EFI 
> platforms.
>   @section Lockdown when booting on a secure setup
>   
>   The GRUB can be locked down when booted on a secure boot environment, for example
> -if the UEFI secure boot is enabled. On a locked down configuration, the GRUB 
> will
> -be restricted and some operations/commands cannot be executed.
> +if UEFI or Power secure boot is enabled. On a locked down configuration, the
> +GRUB will be restricted and some operations/commands cannot be executed.
>   
>   The @samp{lockdown} variable is set to @samp{y} when the GRUB is locked down.
>   Otherwise it does not exit.
> diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
> index 4aa4cf263d94..775a031f1843 100644
> --- a/grub-core/Makefile.core.def
> +++ b/grub-core/Makefile.core.def
> @@ -317,6 +317,7 @@ kernel = {
>     powerpc_ieee1275 = kern/powerpc/cache.S;
>     powerpc_ieee1275 = kern/powerpc/dl.c;
>     powerpc_ieee1275 = kern/powerpc/compiler-rt.S;
> +  powerpc_ieee1275 = kern/lockdown.c;
>   
>     sparc64_ieee1275 = kern/sparc64/cache.S;
>     sparc64_ieee1275 = kern/sparc64/dl.c;
> diff --git a/grub-core/kern/ieee1275/init.c b/grub-core/kern/ieee1275/init.c
> index 4586bec939b2..5faf4e736074 100644
> --- a/grub-core/kern/ieee1275/init.c
> +++ b/grub-core/kern/ieee1275/init.c
> @@ -44,6 +44,7 @@
>   #ifdef __sparc__
>   #include <grub/machine/kernel.h>
>   #endif
> +#include <grub/lockdown.h>
>   
>   /* The maximum heap size we're going to claim. Not used by sparc.
>      We allocate 1/4 of the available memory under 4G, up to this limit. */
> @@ -442,6 +443,30 @@ grub_parse_cmdline (void)
>       }
>   }
>   
> +static void
> +grub_get_ieee1275_secure_boot (void)
> +{
> +  grub_ieee1275_phandle_t root;
> +  int rc;
> +  grub_uint32_t is_sb;
> +
> +  grub_ieee1275_finddevice ("/", &root);
> +
> +  rc = grub_ieee1275_get_integer_property (root, "ibm,secure-boot", &is_sb,
> +                                           sizeof (is_sb), 0);
> +
> +  /* ibm,secure-boot:
> +   * 0 - disabled
> +   * 1 - audit
> +   * 2 - enforce
> +   * 3 - enforce + OS-specific behaviour
> +   *
> +   * We only support enforce.
> +   */
> +  if (rc >= 0 && is_sb >= 2)
> +    grub_lockdown ();
> +}
> +
>   grub_addr_t grub_modbase;
>   
>   void
> @@ -467,6 +492,8 @@ grub_machine_init (void)
>   #else
>     grub_install_get_time_ms (grub_rtc_get_time_ms);
>   #endif
> +
> +  grub_get_ieee1275_secure_boot ();
>   }
>   
>   void
> diff --git a/include/grub/lockdown.h b/include/grub/lockdown.h
> index 40531fa823bf..ebfee4bf06e7 100644
> --- a/include/grub/lockdown.h
> +++ b/include/grub/lockdown.h
> @@ -24,7 +24,8 @@
>   #define GRUB_LOCKDOWN_DISABLED       0
>   #define GRUB_LOCKDOWN_ENABLED        1
>   
> -#ifdef GRUB_MACHINE_EFI
> +#if defined(GRUB_MACHINE_EFI) || \
> +    (defined(__powerpc__) && defined(GRUB_MACHINE_IEEE1275))
>   extern void
>   EXPORT_FUNC (grub_lockdown) (void);
>   extern int