From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
Date: Mon, 28 Sep 2020 11:11:17 +1000
Subject: [PATCH] ieee1275: enter lockdown based on /ibm,secure-boot

If the 'ibm,secure-boot' property of the root node is 2 or greater,
enter lockdown.

Signed-off-by: Daniel Axtens <dja@axtens.net>
---
 grub-core/Makefile.core.def    |  1 +
 grub-core/kern/ieee1275/init.c | 27 +++++++++++++++++++++++++++
 include/grub/lockdown.h        |  3 ++-
 docs/grub.texi                 |  4 ++--
 4 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index 6bddc841b85..3f3459b2c70 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -323,6 +323,7 @@ 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 937c1bc44cb..fc7d9712729 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 minimal heap size we can live with. */
 #define HEAP_MIN_SIZE		(unsigned long) (2 * 1024 * 1024)
@@ -271,6 +272,30 @@ 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
@@ -296,6 +321,8 @@ 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 40531fa823b..ebfee4bf06e 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
diff --git a/docs/grub.texi b/docs/grub.texi
index 4816be85611..a4da9c2a1b9 100644
--- a/docs/grub.texi
+++ b/docs/grub.texi
@@ -6227,8 +6227,8 @@ 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.