From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Peter Jones <pjones@redhat.com>

Date: Fri, 26 Feb 2021 01:43:30 +0100

Subject: [PATCH] util/mkimage: Add an option to import SBAT metadata into a

 .sbat section

Add a --sbat option to the grub-mkimage tool which allows us to import

an SBAT metadata formatted as a CSV file into a .sbat section of the

EFI binary.

Signed-off-by: Peter Jones <pjones@redhat.com>

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

---

 util/grub-install-common.c  |  2 +-

 util/grub-mkimage.c         | 15 ++++++++++++++-

 util/mkimage.c              | 44 +++++++++++++++++++++++++++++++++++++-------

 include/grub/util/install.h |  3 ++-

 docs/grub.texi              | 21 +++++++++++++++++++++

 5 files changed, 75 insertions(+), 10 deletions(-)

diff --git a/util/grub-install-common.c b/util/grub-install-common.c

index d49a93d4740..b4192cf47a3 100644

--- a/util/grub-install-common.c

+++ b/util/grub-install-common.c

@@ -498,7 +498,7 @@ grub_install_make_image_wrap_file (const char *dir, const char *prefix,

   grub_install_generate_image (dir, prefix, fp, outname,

 			       modules.entries, memdisk_path,

 			       pubkeys, npubkeys, config_path, tgt,

-			       note, compression);

+			       note, compression, NULL);

   while (dc--)

     grub_install_pop_module ();

 }

diff --git a/util/grub-mkimage.c b/util/grub-mkimage.c

index 1e0bcf1bf4f..c674f76c42a 100644

--- a/util/grub-mkimage.c

+++ b/util/grub-mkimage.c

@@ -80,6 +80,7 @@ static struct argp_option options[] = {

   {"output",  'o', N_("FILE"), 0, N_("output a generated image to FILE [default=stdout]"), 0},

   {"format",  'O', N_("FORMAT"), 0, 0, 0},

   {"compression",  'C', "(xz|none|auto)", 0, N_("choose the compression to use for core image"), 0},

+  {"sbat", 's', N_("FILE"), 0, N_("SBAT metadata"), 0},

   {"verbose",     'v', 0,      0, N_("print verbose messages."), 0},

   { 0, 0, 0, 0, 0, 0 }

 };

@@ -121,6 +122,7 @@ struct arguments

   size_t npubkeys;

   char *font;

   char *config;

+  char *sbat;

   int note;

   const struct grub_install_image_target_desc *image_target;

   grub_compression_t comp;

@@ -215,6 +217,13 @@ argp_parser (int key, char *arg, struct argp_state *state)

       arguments->prefix = xstrdup (arg);

       break;

+    case 's':

+      if (arguments->sbat)

+	free (arguments->sbat);

+

+      arguments->sbat = xstrdup (arg);

+      break;

+

     case 'v':

       verbosity++;

       break;

@@ -299,7 +308,8 @@ main (int argc, char *argv[])

 			       arguments.memdisk, arguments.pubkeys,

 			       arguments.npubkeys, arguments.config,

 			       arguments.image_target, arguments.note,

-			       arguments.comp);

+			       arguments.comp,

+			       arguments.sbat);

   grub_util_file_sync  (fp);

   fclose (fp);

@@ -310,5 +320,8 @@ main (int argc, char *argv[])

   if (arguments.output)

     free (arguments.output);

+  if (arguments.sbat)

+    free (arguments.sbat);

+

   return 0;

 }

diff --git a/util/mkimage.c b/util/mkimage.c

index 938a06a2d3f..44e2b8adfd8 100644

--- a/util/mkimage.c

+++ b/util/mkimage.c

@@ -1032,12 +1032,14 @@ grub_install_generate_image (const char *dir, const char *prefix,

 			     size_t npubkeys, char *config_path,

 			     const struct grub_install_image_target_desc *image_target,

 			     int note,

-			     grub_compression_t comp)

+			     grub_compression_t comp,

+			     const char *sbat_path)

 {

   char *kernel_img, *core_img;

   size_t kernel_size, total_module_size, core_size, exec_size;

   size_t memdisk_size = 0, config_size = 0, config_size_pure = 0;

   size_t prefix_size = 0;

+  size_t sbat_size = 0;

   char *kernel_path;

   size_t offset;

   struct grub_util_path_list *path_list, *p, *next;

@@ -1085,6 +1087,9 @@ grub_install_generate_image (const char *dir, const char *prefix,

       total_module_size += memdisk_size + sizeof (struct grub_module_header);

     }

+  if (sbat_path != NULL && image_target->id != IMAGE_EFI)

+    grub_util_error (_(".sbat section can be embedded into EFI images only"));

+

   if (config_path)

     {

       config_size_pure = grub_util_get_image_size (config_path) + 1;

@@ -1446,8 +1451,9 @@ grub_install_generate_image (const char *dir, const char *prefix,

       break;

     case IMAGE_EFI:

       {

-	char *pe_img, *header;

+	char *pe_img, *pe_sbat, *header;

 	struct grub_pe32_section_table *section;

+	size_t n_sections = 4;

 	size_t scn_size;

 	grub_uint32_t vma, raw_data;

 	size_t pe_size, header_size;

@@ -1462,8 +1468,15 @@ grub_install_generate_image (const char *dir, const char *prefix,

 	  header_size = EFI64_HEADER_SIZE;

 	vma = raw_data = header_size;

+

+	if (sbat_path != NULL)

+	  {

+	    sbat_size = ALIGN_ADDR (grub_util_get_image_size (sbat_path));

+	    sbat_size = ALIGN_UP (sbat_size, GRUB_PE32_FILE_ALIGNMENT);

+	  }

+

 	pe_size = ALIGN_UP (header_size + core_size, GRUB_PE32_FILE_ALIGNMENT) +

-          ALIGN_UP (layout.reloc_size, GRUB_PE32_FILE_ALIGNMENT);

+          ALIGN_UP (reloc_size, GRUB_PE32_FILE_ALIGNMENT) + sbat_size;

 	header = pe_img = xcalloc (1, pe_size);

 	memcpy (pe_img + raw_data, core_img, core_size);

@@ -1478,7 +1491,10 @@ grub_install_generate_image (const char *dir, const char *prefix,

 					      + GRUB_PE32_SIGNATURE_SIZE);

 	c->machine = grub_host_to_target16 (image_target->pe_target);

-	c->num_sections = grub_host_to_target16 (4);

+	if (sbat_path != NULL)

+	  n_sections++;

+

+	c->num_sections = grub_host_to_target16 (n_sections);

 	c->time = grub_host_to_target32 (time (0));

 	c->characteristics = grub_host_to_target16 (GRUB_PE32_EXECUTABLE_IMAGE

 						    | GRUB_PE32_LINE_NUMS_STRIPPED

@@ -1542,9 +1558,10 @@ grub_install_generate_image (const char *dir, const char *prefix,

 				   GRUB_PE32_SCN_MEM_READ);

 	scn_size = ALIGN_UP (kernel_size - exec_size, GRUB_PE32_FILE_ALIGNMENT);

-	PE_OHDR (o32, o64, data_size) = grub_host_to_target32 (scn_size +

+	/* ALIGN_UP (sbat_size, GRUB_PE32_FILE_ALIGNMENT) is done earlier. */

+	PE_OHDR (o32, o64, data_size) = grub_host_to_target32 (scn_size + sbat_size +

 							       ALIGN_UP (total_module_size,

-

+									 GRUB_PE32_FILE_ALIGNMENT));

 	section = init_pe_section (image_target, section, ".data",

 				   &vma, scn_size, image_target->section_align,

@@ -1553,7 +1570,7 @@ grub_install_generate_image (const char *dir, const char *prefix,

 				   GRUB_PE32_SCN_MEM_READ |

 				   GRUB_PE32_SCN_MEM_WRITE);

-	scn_size = pe_size - reloc_size - raw_data;

+	scn_size = pe_size - reloc_size - sbat_size - raw_data;

 	section = init_pe_section (image_target, section, "mods",

 				   &vma, scn_size, image_target->section_align,

 				   &raw_data, scn_size,

@@ -1561,6 +1578,19 @@ grub_install_generate_image (const char *dir, const char *prefix,

 				   GRUB_PE32_SCN_MEM_READ |

 				   GRUB_PE32_SCN_MEM_WRITE);

+	if (sbat_path != NULL)

+	  {

+	    pe_sbat = pe_img + raw_data;

+	    grub_util_load_image (sbat_path, pe_sbat);

+

+	    section = init_pe_section (image_target, section, ".sbat",

+				       &vma, sbat_size,

+				       image_target->section_align,

+				       &raw_data, sbat_size,

+				       GRUB_PE32_SCN_CNT_INITIALIZED_DATA |

+				       GRUB_PE32_SCN_MEM_READ);

+	  }

+

 	scn_size = reloc_size;

 	PE_OHDR (o32, o64, base_relocation_table.rva) = grub_host_to_target32 (vma);

 	PE_OHDR (o32, o64, base_relocation_table.size) = grub_host_to_target32 (scn_size);

diff --git a/include/grub/util/install.h b/include/grub/util/install.h

index aedcd29f905..02ae1c6425e 100644

--- a/include/grub/util/install.h

+++ b/include/grub/util/install.h

@@ -176,7 +176,8 @@ grub_install_generate_image (const char *dir, const char *prefix,

 			     char *config_path,

 			     const struct grub_install_image_target_desc *image_target,

 			     int note,

-			     grub_compression_t comp);

+			     grub_compression_t comp,

+			     const char *sbat_path);

 const struct grub_install_image_target_desc *

 grub_install_get_image_target (const char *arg);

diff --git a/docs/grub.texi b/docs/grub.texi

index 446574f3ddb..24840d00cf7 100644

--- a/docs/grub.texi

+++ b/docs/grub.texi

@@ -5498,6 +5498,7 @@ environment variables and commands are listed in the same order.

 @menu

 * Authentication and authorisation:: Users and access control

 * Using digital signatures::         Booting digitally signed code

+* Secure Boot Advanced Targeting::   Embedded information for generation number based revocation

 * Lockdown::                           Lockdown when booting on a secure setup

 @end menu

@@ -5660,6 +5661,26 @@ or BIOS) configuration to cause the machine to boot from a different

 (attacker-controlled) device.  GRUB is at best only one link in a

 secure boot chain.

+

+@node Secure Boot Advanced Targeting

+@section Embedded information for generation number based revocation

+

+The Secure Boot Advanced Targeting (SBAT) is a mechanism to allow the revocation

+of components in the boot path by using generation numbers embedded into the EFI

+binaries. The SBAT metadata is located in an .sbat data section that has set of

+UTF-8 strings as comma-separated values (CSV). See

+@uref{https://github.com/rhboot/shim/blob/main/SBAT.md} for more details.

+

+To add a data section containing the SBAT information into the binary, the

+@option{--sbat} option of @command{grub-mkimage} command should be used. The content

+of a CSV file, encoded with UTF-8, is copied as is to the .sbat data section into

+the generated EFI binary. The CSV file can be stored anywhere on the file system.

+

+@example

+grub-mkimage -O x86_64-efi -o grubx64.efi -p '(tftp)/grub' --sbat sbat.csv efinet tftp

+@end example

+

+

 @node Lockdown

 @section Lockdown when booting on a secure setup