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