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From:   Daniel Kiper <daniel.kiper@oracle.com>
To:     grub-devel@gnu.org, linux-kernel@vger.kernel.org,
        trenchboot-devel@googlegroups.com, x86@kernel.org
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Subject: [GRUB PATCH RFC 16/18] i386/txt: Add Intel TXT ACM module support
Date:   Tue,  5 May 2020 01:21:30 +0200
Message-Id: <20200504232132.23570-17-daniel.kiper@oracle.com>
In-Reply-To: <20200504232132.23570-1-daniel.kiper@oracle.com>
References: <20200504232132.23570-1-daniel.kiper@oracle.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Ross Philipson <ross.philipson@oracle.com>

Signed-off-by: Ross Philipson <ross.philipson@oracle.com>
Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
---
 grub-core/loader/i386/txt/acmod.c | 575 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 575 insertions(+)
 create mode 100644 grub-core/loader/i386/txt/acmod.c

diff --git a/grub-core/loader/i386/txt/acmod.c b/grub-core/loader/i386/txt/acmod.c
new file mode 100644
index 000000000..ed2fbab7b
--- /dev/null
+++ b/grub-core/loader/i386/txt/acmod.c
@@ -0,0 +1,575 @@
+/*
+ * acmod.c: support functions for use of Intel(r) TXT Authenticated
+ *          Code (AC) Modules
+ *
+ * Copyright (c) 2003-2011, Intel Corporation
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ *     copyright notice, this list of conditions and the following
+ *     disclaimer in the documentation and/or other materials provided
+ *     with the distribution.
+ *   * Neither the name of the Intel Corporation nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2020  Oracle and/or its affiliates.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/loader.h>
+#include <grub/memory.h>
+#include <grub/normal.h>
+#include <grub/err.h>
+#include <grub/misc.h>
+#include <grub/types.h>
+#include <grub/dl.h>
+#include <grub/cpu/relocator.h>
+#include <grub/i386/cpuid.h>
+#include <grub/i386/msr.h>
+#include <grub/i386/txt.h>
+
+/*
+ * This checks to see if two numbers multiplied together are larger
+ *   than the type that they are.  Returns TRUE if OVERFLOWING.
+ *   If the first parameter "x" is greater than zero and
+ *   if that is true, that the largest possible value 0xFFFFFFFF / "x"
+ *   is less than the second parameter "y".  If "y" is zero then
+ *   it will also fail because no unsigned number is less than zero.
+ */
+static inline int
+multiply_overflow_u32 (grub_uint32_t x, grub_uint32_t y)
+{
+  /* Use x instead of (x > 0)? */
+  return (x > 0) ? ((((grub_uint32_t)(~0))/x) < y) : 0;
+}
+
+/*
+ *  These three "plus overflow" functions take a "x" value
+ *    and add the "y" value to it and if the two values are
+ *    greater than the size of the variable type, they will
+ *    overflow the type and end up with a smaller value and
+ *    return TRUE - that they did overflow.  i.e.
+ */
+static inline int plus_overflow_u32 (grub_uint32_t x, grub_uint32_t y)
+{
+  return ((((grub_uint32_t)(~0)) - x) < y);
+}
+
+static struct grub_txt_acm_info_table*
+get_acmod_info_table (struct grub_txt_acm_header* hdr)
+{
+  grub_uint32_t user_area_off;
+
+  /* Overflow? */
+  if ( plus_overflow_u32 (hdr->header_len, hdr->scratch_size) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("ACM header length plus scratch size overflows"));
+      return NULL;
+    }
+
+  if ( multiply_overflow_u32 ((hdr->header_len + hdr->scratch_size), 4) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("ACM header length and scratch size in bytes overflows"));
+      return NULL;
+    }
+
+  /*
+   * This fn assumes that the ACM has already passed at least the initial
+   * is_acmod() checks.
+   */
+
+  user_area_off = (hdr->header_len + hdr->scratch_size) * 4;
+
+  /* Overflow? */
+  if ( plus_overflow_u32 (user_area_off, sizeof(struct grub_txt_acm_info_table)) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("user_area_off plus acm_info_table_t size overflows"));
+      return NULL;
+    }
+
+  /* Check that table is within module. */
+  if ( user_area_off + sizeof(struct grub_txt_acm_info_table) > hdr->size * 4 )
+    {
+      /* TODO: Is (grub_uint32_t) correct??? */
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("ACM info table size too large: %x > %x"),
+		  user_area_off + (grub_uint32_t)sizeof(struct grub_txt_acm_info_table), hdr->size * 4);
+      return NULL;
+    }
+
+  /* Overflow? */
+  if ( plus_overflow_u32 ((grub_uint32_t)(unsigned long)hdr, user_area_off) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("hdr plus user_area_off overflows"));
+      return NULL;
+    }
+
+    return (struct grub_txt_acm_info_table *)((unsigned long)hdr + user_area_off);
+}
+
+static struct grub_txt_acm_chipset_id_list*
+get_acmod_chipset_list (struct grub_txt_acm_header *hdr)
+{
+  struct grub_txt_acm_info_table *info_table;
+  grub_uint32_t size, id_list_off;
+  struct grub_txt_acm_chipset_id_list *chipset_id_list;
+
+  /* This fn assumes that the ACM has already passed the is_acmod() checks */
+
+  info_table = get_acmod_info_table (hdr);
+  if ( !info_table )
+    return NULL;
+  id_list_off = info_table->chipset_id_list;
+
+  size = hdr->size * 4;
+
+  /* Overflow? */
+  if ( plus_overflow_u32 (id_list_off, sizeof(struct grub_txt_acm_chipset_id)) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("id_list_off plus acm_chipset_id_t size overflows"));
+      return NULL;
+    }
+
+  /* Check that chipset id table is w/in ACM */
+  if ( id_list_off + sizeof(struct grub_txt_acm_chipset_id) > size )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("chipset id list is too big: %x"), id_list_off);
+      return NULL;
+    }
+
+  /* Overflow? */
+  if ( plus_overflow_u32 ((grub_uint32_t)(unsigned long)hdr, id_list_off) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("hdr plus id_list_off overflows"));
+      return NULL;
+    }
+
+  chipset_id_list = (struct grub_txt_acm_chipset_id_list*)
+                    ((unsigned long)hdr + id_list_off);
+
+  /* Overflows? */
+  if ( multiply_overflow_u32 (chipset_id_list->count,
+                              sizeof(struct grub_txt_acm_chipset_id)) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("size of acm_chipset_id_list overflows"));
+      return NULL;
+    }
+
+  if ( plus_overflow_u32 (id_list_off + sizeof(struct grub_txt_acm_chipset_id),
+        chipset_id_list->count * sizeof(struct grub_txt_acm_chipset_id)) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("size of all entries overflows"));
+      return NULL;
+    }
+
+  /* Check that all entries are w/in ACM */
+  if ( id_list_off + sizeof(struct grub_txt_acm_chipset_id) +
+       chipset_id_list->count * sizeof(struct grub_txt_acm_chipset_id) > size )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("ACM chipset id entries are too big: %x"),
+		  chipset_id_list->count);
+      return NULL;
+    }
+
+  return chipset_id_list;
+}
+
+static struct grub_txt_acm_processor_id_list*
+get_acmod_processor_list (struct grub_txt_acm_header* hdr)
+{
+  struct grub_txt_acm_info_table *info_table;
+  grub_uint32_t size, id_list_off;
+  struct grub_txt_acm_processor_id_list *proc_id_list;
+
+  /* This fn assumes that the ACM has already passed the is_acmod() checks */
+
+  info_table = get_acmod_info_table(hdr);
+  if ( info_table == NULL )
+    return NULL;
+  id_list_off = info_table->processor_id_list;
+
+  size = hdr->size * 4;
+
+  /* Overflow? */
+  if ( plus_overflow_u32 (id_list_off, sizeof(struct grub_txt_acm_processor_id)) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("id_list_off plus acm_processor_id_t size overflows"));
+      return NULL;
+    }
+
+  /* Check that processor id table is w/in ACM */
+  if ( id_list_off + sizeof(struct grub_txt_acm_processor_id) > size )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("ACM processor id list is too big: %x"), id_list_off);
+      return NULL;
+    }
+
+  /* Overflow? */
+  if ( plus_overflow_u32 ((unsigned long)hdr, id_list_off) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("hdr plus id_list_off overflows"));
+      return NULL;
+    }
+
+  proc_id_list = (struct grub_txt_acm_processor_id_list *)
+                             ((unsigned long)hdr + id_list_off);
+
+  /* Overflows? */
+  if ( multiply_overflow_u32 (proc_id_list->count,
+             sizeof(struct grub_txt_acm_processor_id)) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("size of acm_processor_id_list overflows"));
+      return NULL;
+    }
+
+  if ( plus_overflow_u32 (id_list_off + sizeof(struct grub_txt_acm_processor_id),
+        proc_id_list->count * sizeof(struct grub_txt_acm_processor_id)) )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("size of all entries overflows"));
+      return NULL;
+    }
+
+  /* Check that all entries are w/in ACM */
+  if ( id_list_off + sizeof(struct grub_txt_acm_processor_id) +
+         proc_id_list->count * sizeof(struct grub_txt_acm_processor_id) > size )
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("ACM processor id entries are too big: %x"),
+		  proc_id_list->count);
+      return NULL;
+    }
+
+  return proc_id_list;
+}
+
+static int
+is_acmod (const void *acmod_base, grub_uint32_t acmod_size,
+         grub_uint8_t *type_out)
+{
+  struct grub_txt_acm_header *acm_hdr = (struct grub_txt_acm_header *)acmod_base;
+  struct grub_txt_acm_info_table *info_table;
+
+  /* First check size */
+  if ( acmod_size < sizeof (struct grub_txt_acm_header) )
+    return 0;
+
+  /* Then check overflow */
+  if ( multiply_overflow_u32 (acm_hdr->size, 4) )
+    return 0;
+
+  /* Then check size equivalency */
+  if ( acmod_size != acm_hdr->size * 4 )
+    return 0;
+
+  /* Then check type and vendor */
+  if ( (acm_hdr->module_type != GRUB_TXT_ACM_MODULE_TYPE) ||
+       (acm_hdr->module_vendor != GRUB_TXT_ACM_MODULE_VENDOR_INTEL) )
+    return 0;
+
+  info_table = get_acmod_info_table (acm_hdr);
+  if ( !info_table )
+    return 0;
+
+  /* Check if ACM UUID is present */
+  if ( grub_memcmp (&(info_table->uuid), GRUB_TXT_ACM_UUID, 16) )
+    return 0;
+
+  if ( type_out )
+    *type_out = info_table->chipset_acm_type;
+
+  return 1;
+}
+
+static struct grub_txt_acm_header*
+get_bios_sinit (void *sinit_region_base)
+{
+  grub_uint8_t *txt_heap = grub_txt_get_heap ();
+  struct grub_txt_bios_data *bios_data = grub_txt_bios_data_start (txt_heap);
+  struct grub_txt_acm_header *bios_sinit;
+
+  if ( !sinit_region_base )
+     return NULL;
+
+  if ( bios_data->bios_sinit_size == 0 )
+    return NULL;
+
+  /* BIOS has loaded an SINIT module, so verify that it is valid */
+  grub_dprintf ("slaunch", "BIOS has already loaded an SINIT module\n");
+
+  bios_sinit = (struct grub_txt_acm_header *)sinit_region_base;
+
+  /* Is it a valid SINIT module? */
+  if ( !grub_txt_is_sinit_acmod (sinit_region_base, bios_data->bios_sinit_size) ||
+       !grub_txt_acmod_match_platform (bios_sinit) )
+    return NULL;
+
+  return bios_sinit;
+}
+
+grub_uint32_t
+grub_txt_supported_os_sinit_data_ver (struct grub_txt_acm_header* hdr)
+{
+  static struct grub_txt_acm_info_table *info_table;
+
+  /* Assumes that it passed is_sinit_acmod() */
+  info_table = get_acmod_info_table (hdr);
+
+  if ( info_table == NULL )
+    return 0;
+
+  return info_table->os_sinit_data_ver;
+}
+
+grub_uint32_t
+grub_txt_get_sinit_capabilities (struct grub_txt_acm_header* hdr)
+{
+  static struct grub_txt_acm_info_table *info_table;
+
+  /* Assumes that it passed is_sinit_acmod() */
+  info_table = get_acmod_info_table (hdr);
+
+  if ( info_table == NULL || info_table->version < 3 )
+    return 0;
+
+  return info_table->capabilities;
+}
+
+int
+grub_txt_is_sinit_acmod (const void *acmod_base, grub_uint32_t acmod_size)
+{
+  grub_uint8_t type;
+
+  if ( !is_acmod (acmod_base, acmod_size, &type) )
+    return 0;
+
+  if ( type != GRUB_TXT_ACM_CHIPSET_TYPE_SINIT )
+    return 0;
+
+  return 1;
+}
+
+/* Format of VER.FSBIF and VER.QPIIF registers. */
+typedef union {
+  grub_uint64_t _raw;
+  struct {
+     grub_uint64_t reserved   : 31;
+     grub_uint64_t prod_fused : 1;
+  };
+} grub_txt_ver_fsbif_qpiif_t;
+
+int
+grub_txt_acmod_match_platform (struct grub_txt_acm_header *hdr)
+{
+  union grub_txt_didvid didvid;
+  grub_uint32_t fms, ign, i;
+  grub_uint64_t platform_id;
+  grub_txt_ver_fsbif_qpiif_t ver;
+  struct grub_txt_acm_chipset_id_list *chipset_id_list;
+  struct grub_txt_acm_chipset_id *chipset_id;
+  struct grub_txt_acm_processor_id_list *proc_id_list;
+  struct grub_txt_acm_processor_id *proc_id;
+  struct grub_txt_acm_info_table *info_table;
+
+  /* This fn assumes that the ACM has already passed the is_acmod() checks */
+
+  /* Get chipset fusing, device, and vendor id info */
+  didvid.value = grub_txt_reg_pub_readq (GRUB_TXT_DIDVID);
+
+  ver._raw = grub_txt_reg_pub_readq (GRUB_TXT_VER_FSBIF);
+  if ( (ver._raw & 0xffffffff) == 0xffffffff ||
+       (ver._raw & 0xffffffff) == 0x00 ) /* Need to use VER.QPIIF */
+    ver._raw = grub_txt_reg_pub_readq (GRUB_TXT_VER_QPIIF);
+
+  grub_dprintf ("slaunch", "chipset production fused: %x, "
+		"chipset vendor: 0x%x, device: 0x%x, revision: 0x%x\n",
+		ver.prod_fused, didvid.vid, didvid.did, didvid.rid);
+
+  grub_cpuid (1, fms, ign, ign, ign);
+  platform_id = grub_rdmsr (GRUB_MSR_X86_PLATFORM_ID);
+
+  grub_dprintf ("slaunch", "processor family/model/stepping: 0x%x, "
+		"platform id: 0x%" PRIxGRUB_UINT64_T "\n", fms, platform_id);
+
+  /*
+   * Check if chipset fusing is same. Note the DEBUG.FUSE bit in the version
+   * is 0 when debug fused so the logic below checking a mismatch is valid.
+   */
+  if ( (ver._raw & GRUB_TXT_VERSION_DEBUG_FUSED) &&
+       (hdr->flags & GRUB_TXT_ACM_FLAG_DEBUG_SIGNED) )
+    {
+      grub_error (GRUB_ERR_BAD_DEVICE, N_("production/debug mismatch between chipset and ACM"));
+      return 0;
+    }
+
+  /* Check if chipset vendor/device/revision IDs match */
+  chipset_id_list = get_acmod_chipset_list (hdr);
+  if ( !chipset_id_list )
+    return 0;
+
+  grub_dprintf ("slaunch", "%d SINIT ACM chipset id entries:\n", chipset_id_list->count);
+
+  chipset_id = (struct grub_txt_acm_chipset_id *) ((grub_addr_t)chipset_id_list + sizeof (chipset_id_list->count));
+  for (i = 0; i < chipset_id_list->count; i++, chipset_id++)
+    {
+      grub_dprintf ("slaunch", "  vendor: 0x%x, device: 0x%x, flags: 0x%x, "
+		    "revision: 0x%x, extended: 0x%x\n", chipset_id->vendor_id,
+		    chipset_id->device_id, chipset_id->flags,
+		    chipset_id->revision_id, chipset_id->extended_id);
+
+      if ( (didvid.vid == chipset_id->vendor_id ) &&
+           (didvid.did == chipset_id->device_id ) &&
+           ( ( ( (chipset_id->flags & GRUB_TXT_ACM_REVISION_ID_MASK) == 0) &&
+                 (didvid.rid == chipset_id->revision_id) ) ||
+               ( ( (chipset_id->flags & GRUB_TXT_ACM_REVISION_ID_MASK) == 1) &&
+                 ( (didvid.rid & chipset_id->revision_id) != 0 ) ) ) )
+            break;
+    }
+
+  if ( i >= chipset_id_list->count )
+    {
+      grub_error (GRUB_ERR_BAD_DEVICE, N_("chipset id mismatch"));
+      return 0;
+    }
+
+  /* Check if processor family/model/stepping and platform IDs match */
+  info_table = get_acmod_info_table (hdr);
+  if ( !info_table )
+    return 0;
+
+  /*
+   * Logic inverted from oringal to avoid the if block. Not sure what drives
+   * the logic of not checking processor infrmation for version 4 or less.
+   */
+  if ( info_table->version < 4 )
+    return 1;
+
+  proc_id_list = get_acmod_processor_list(hdr);
+  if ( !proc_id_list )
+    return 1;
+
+  grub_dprintf ("slaunch", "%d SINIT ACM processor id entries:\n", proc_id_list->count);
+
+  proc_id = (struct grub_txt_acm_processor_id *) ((grub_addr_t)proc_id_list + sizeof (proc_id_list->count));
+  for (i = 0; i < proc_id_list->count; i++, proc_id++)
+    {
+      grub_dprintf ("slaunch", "  fms: 0x%x, fms_mask: 0x%x, platform_id: 0x%" PRIxGRUB_UINT64_T
+		    ", platform_mask: 0x%" PRIxGRUB_UINT64_T "\n", proc_id->fms, proc_id->fms_mask,
+		    proc_id->platform_id, proc_id->platform_mask);
+
+      if ( (proc_id->fms == (fms & proc_id->fms_mask)) &&
+           (proc_id->platform_id == (platform_id & proc_id->platform_mask)) )
+        break;
+    }
+
+  if ( i >= proc_id_list->count )
+    {
+      grub_error (GRUB_ERR_BAD_DEVICE, N_("chipset id mismatch"));
+      return 0;
+    }
+
+  return 1;
+}
+
+struct grub_txt_acm_header *
+grub_txt_sinit_select (struct grub_txt_acm_header *sinit)
+{
+  struct grub_txt_acm_header *bios_sinit;
+  void *sinit_region_base;
+  grub_uint32_t sinit_region_size;
+
+  sinit_region_base = (void *)(grub_addr_t) grub_txt_reg_pub_readq (GRUB_TXT_SINIT_BASE);
+  sinit_region_size = (grub_uint32_t) grub_txt_reg_pub_readq (GRUB_TXT_SINIT_SIZE);
+
+  grub_dprintf ("slaunch", "TXT.SINIT.BASE: %p\nTXT.SINIT.SIZE: 0x%"
+		PRIxGRUB_UINT32_T "\n", sinit_region_base, sinit_region_size);
+
+  if (sinit_region_base == NULL)
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("no SINIT ACM final resting place"));
+      return NULL;
+    }
+
+  if (sinit != NULL)
+    grub_dprintf ("slaunch", "SINIT ACM date: %" PRIxGRUB_UINT32_T "\n", sinit->date);
+
+  bios_sinit = get_bios_sinit (sinit_region_base);
+
+  /* Does BIOS provide SINIT ACM? */
+  if (bios_sinit != NULL)
+    {
+      grub_dprintf ("slaunch", "BIOS SINIT ACM date: %" PRIxGRUB_UINT32_T "\n",
+		    bios_sinit->date);
+
+      if (sinit == NULL)
+        {
+	  grub_dprintf ("slaunch", "no SINIT ACM provided. Using BIOS SINIT ACM\n");
+          return bios_sinit;
+        }
+
+      if (bios_sinit->date >= sinit->date)
+        {
+          grub_dprintf ("slaunch", "BIOS provides newer or same SINIT ACM, so, using BIOS one\n");
+          return bios_sinit;
+        }
+
+      grub_dprintf ("slaunch", "BIOS provides older SINIT ACM, so, ignoring BIOS one\n");
+    }
+
+  /* Fail if there is no SINIT ACM. */
+  if (sinit == NULL)
+    return NULL;
+
+  /* Our SINIT ACM is newer than BIOS one or BIOS does not have one. */
+
+  if (multiply_overflow_u32 (sinit->size, 4))
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE, N_("SINIT ACM size in bytes overflows"));
+      return NULL;
+    }
+
+  if ((sinit->size * 4) > sinit_region_size)
+    {
+      grub_error (GRUB_ERR_OUT_OF_MEMORY,
+		  N_("SINIT ACM does not fit into final resting place: 0x%"
+		  PRIxGRUB_UINT32_T "\n"), sinit->size * 4);
+      return NULL;
+    }
+
+  grub_memcpy (sinit_region_base, sinit, sinit->size * 4);
+
+  return sinit_region_base;
+}
-- 
2.11.0