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grub2/0409-powerpc-ieee1275-Add-support-for-signing-GRUB-with-a.patch
Nicolas Frayer 17ffd9b3e0 powerpc: Add appended signature feature 
Resolves: #RHEL-24510
Signed-off-by: Nicolas Frayer <nfrayer@redhat.com>
2025-11-27 14:40:11 +01:00

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Date: Mon, 6 Oct 2025 12:54:46 +0530
Subject: [PATCH] powerpc/ieee1275: Add support for signing GRUB with an
appended signature
Add infrastructure to allow firmware to verify the integrity of GRUB
by use of a Linux-kernel-module-style appended signature. We initially
target powerpc-ieee1275, but the code should be extensible to other
platforms.
Usually these signatures are appended to a file without modifying the
ELF file itself. (This is what the 'sign-file' tool does, for example.)
The verifier loads the signed file from the file system and looks at the
end of the file for the appended signature. However, on powerpc-ieee1275
platforms, the bootloader is often stored directly in the PReP partition
as raw bytes without a file-system. This makes determining the location
of an appended signature more difficult.
To address this, we add a new ELF Note.
The name field of shall be the string "Appended-Signature", zero-padded
to 4 byte alignment. The type field shall be 0x41536967 (the ASCII values
for the string "ASig"). It must be the final section in the ELF binary.
The description shall contain the appended signature structure as defined
by the Linux kernel. The description will also be padded to be a multiple
of 4 bytes. The padding shall be added before the appended signature
structure (not at the end) so that the final bytes of a signed ELF file
are the appended signature magic.
A subsequent patch documents how to create a GRUB core.img validly signed
under this scheme.
Signed-off-by: Rashmica Gupta <rashmica.g@gmail.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Avnish Chouhan <avnish@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
include/grub/util/install.h | 2 +-
include/grub/util/mkimage.h | 4 +--
util/grub-install-common.c | 28 ++++++++++-----------
util/grub-mkimage.c | 19 +++++++-------
util/grub-mkimagexx.c | 61 +++++++++++++++++++++++----------------------
util/mkimage.c | 20 ++++++++-------
6 files changed, 68 insertions(+), 66 deletions(-)
diff --git a/include/grub/util/install.h b/include/grub/util/install.h
index 93c1f0e..14f4489 100644
--- a/include/grub/util/install.h
+++ b/include/grub/util/install.h
@@ -70,7 +70,7 @@
{ "disable-cli", GRUB_INSTALL_OPTIONS_DISABLE_CLI, 0, 0, \
N_("disabled command line interface access"), 0 }, \
{ "x509key", 'x', N_("FILE"), 0, \
- N_("embed FILE as an x509 certificate for appended signature checking"), 0}, \
+ N_("embed FILE as an x509 certificate for appended signature checking"), 0}, \
{ "appended-signature-size", GRUB_INSTALL_OPTIONS_APPENDED_SIGNATURE_SIZE, \
"SIZE", 0, N_("Add a note segment reserving SIZE bytes for an appended signature"), 1}, \
{ "verbose", 'v', 0, 0, \
diff --git a/include/grub/util/mkimage.h b/include/grub/util/mkimage.h
index 881e303..244e39d 100644
--- a/include/grub/util/mkimage.h
+++ b/include/grub/util/mkimage.h
@@ -51,12 +51,12 @@ grub_mkimage_load_image64 (const char *kernel_path,
const struct grub_install_image_target_desc *image_target);
void
grub_mkimage_generate_elf32 (const struct grub_install_image_target_desc *image_target,
- int note, size_t appsig_size, char *sbat, char **core_img, size_t *core_size,
+ int note, char *sbat, size_t appsig_size, char **core_img, size_t *core_size,
Elf32_Addr target_addr,
struct grub_mkimage_layout *layout);
void
grub_mkimage_generate_elf64 (const struct grub_install_image_target_desc *image_target,
- int note, size_t appsig_size, char *sbat, char **core_img, size_t *core_size,
+ int note, char *sbat, size_t appsig_size, char **core_img, size_t *core_size,
Elf64_Addr target_addr,
struct grub_mkimage_layout *layout);
diff --git a/util/grub-install-common.c b/util/grub-install-common.c
index 41251ce..c4b5cb3 100644
--- a/util/grub-install-common.c
+++ b/util/grub-install-common.c
@@ -475,6 +475,7 @@ int
grub_install_parse (int key, char *arg)
{
const char *end;
+
switch (key)
{
case GRUB_INSTALL_OPTIONS_INSTALL_CORE_COMPRESS:
@@ -580,10 +581,11 @@ grub_install_parse (int key, char *arg)
case GRUB_INSTALL_OPTIONS_GRUB_MKIMAGE:
return 1;
case GRUB_INSTALL_OPTIONS_APPENDED_SIGNATURE_SIZE:
- grub_errno = 0;
- appsig_size = grub_strtol(arg, &end, 10);
- if (grub_errno)
- return 0;
+ appsig_size = grub_strtoul (arg, &end, 10);
+ if (*arg == '\0' || *end != '\0')
+ grub_util_error (_("non-numeric or invalid appended signature size `%s'"), arg);
+ else if (appsig_size == 0)
+ grub_util_error (_("appended signature size `%s', and it should not be zero"), arg);
return 1;
default:
return 0;
@@ -709,14 +711,12 @@ grub_install_make_image_wrap_file (const char *dir, const char *prefix,
grub_util_info ("grub-mkimage --directory '%s' --prefix '%s' --output '%s'"
" --format '%s' --compression '%s'"
- " --appended-signture-size %zu %s%s%s\n",
- " --format '%s' --compression '%s'%s%s%s%s\n",
- dir, prefix, outname,
- mkimage_target, compnames[compression],
- appsig_size,
- note ? " --note" : "",
- disable_shim_lock ? " --disable-shim-lock" : "",
- disable_cli ? " --disable-cli" : "", s);
+ " --appended-signature-size %zu %s %s %s %s\n",
+ dir, prefix, outname,
+ mkimage_target, compnames[compression], appsig_size,
+ note ? " --note" : "",
+ disable_shim_lock ? " --disable-shim-lock" : "",
+ disable_cli ? " --disable-cli" : "", s);
free (s);
tgt = grub_install_get_image_target (mkimage_target);
@@ -725,9 +725,7 @@ 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,
- x509keys, nx509keys,
- config_path, tgt,
+ pubkeys, npubkeys, x509keys, nx509keys, config_path, tgt,
note, appsig_size, compression, dtb, sbat,
disable_shim_lock, disable_cli);
while (dc--)
diff --git a/util/grub-mkimage.c b/util/grub-mkimage.c
index 89ca81c..e3511b0 100644
--- a/util/grub-mkimage.c
+++ b/util/grub-mkimage.c
@@ -85,8 +85,8 @@ static struct argp_option options[] = {
{"sbat", 's', N_("FILE"), 0, N_("SBAT metadata"), 0},
{"disable-shim-lock", GRUB_INSTALL_OPTIONS_DISABLE_SHIM_LOCK, 0, 0, N_("disable shim_lock verifier"), 0},
{"disable-cli", GRUB_INSTALL_OPTIONS_DISABLE_CLI, 0, 0, N_("disable command line interface access"), 0},
- {"verbose", 'v', 0, 0, N_("print verbose messages."), 0},
{"appended-signature-size", 'S', N_("SIZE"), 0, N_("Add a note segment reserving SIZE bytes for an appended signature"), 0},
+ {"verbose", 'v', 0, 0, N_("print verbose messages."), 0},
{ 0, 0, 0, 0, 0, 0 }
};
@@ -133,8 +133,8 @@ struct arguments
char *sbat;
int note;
int disable_shim_lock;
- size_t appsig_size;
int disable_cli;
+ size_t appsig_size;
const struct grub_install_image_target_desc *image_target;
grub_compression_t comp;
};
@@ -179,10 +179,11 @@ argp_parser (int key, char *arg, struct argp_state *state)
break;
case 'S':
- grub_errno = 0;
- arguments->appsig_size = grub_strtol(arg, &end, 10);
- if (grub_errno)
- return 0;
+ arguments->appsig_size = grub_strtoul (arg, &end, 10);
+ if (*arg == '\0' || *end != '\0')
+ grub_util_error (_("non-numeric or invalid appended signature size `%s'"), arg);
+ else if (arguments->appsig_size == 0)
+ grub_util_error (_("appended signature size `%s', and it should not be zero"), arg);
break;
case 'm':
@@ -351,9 +352,9 @@ main (int argc, char *argv[])
arguments.npubkeys, arguments.x509keys,
arguments.nx509keys, arguments.config,
arguments.image_target, arguments.note,
- arguments.appsig_size, arguments.comp,
- arguments.dtb, arguments.sbat,
- arguments.disable_shim_lock,
+ arguments.appsig_size,
+ arguments.comp, arguments.dtb,
+ arguments.sbat, arguments.disable_shim_lock,
arguments.disable_cli);
if (grub_util_file_sync (fp) < 0)
diff --git a/util/grub-mkimagexx.c b/util/grub-mkimagexx.c
index b993054..d185246 100644
--- a/util/grub-mkimagexx.c
+++ b/util/grub-mkimagexx.c
@@ -85,15 +85,6 @@ struct grub_ieee1275_note
struct grub_ieee1275_note_desc descriptor;
};
-#define GRUB_APPENDED_SIGNATURE_NOTE_NAME "Appended-Signature"
-#define GRUB_APPENDED_SIGNATURE_NOTE_TYPE 0x41536967 /* "ASig" */
-
-struct grub_appended_signature_note
-{
- Elf32_Nhdr header;
- char name[ALIGN_UP(sizeof (GRUB_APPENDED_SIGNATURE_NOTE_NAME), 4)];
-};
-
#define GRUB_XEN_NOTE_NAME "Xen"
struct fixup_block_list
@@ -124,6 +115,14 @@ struct grub_sbat_note {
char name[ALIGN_UP(sizeof(GRUB_SBAT_NOTE_NAME), 4)];
};
+#define GRUB_APPENDED_SIGNATURE_NOTE_NAME "Appended-Signature"
+#define GRUB_APPENDED_SIGNATURE_NOTE_TYPE 0x41536967 /* "ASig" */
+struct grub_appended_signature_note
+{
+ Elf32_Nhdr header;
+ char name[ALIGN_UP (sizeof (GRUB_APPENDED_SIGNATURE_NOTE_NAME), 4)];
+};
+
static int
is_relocatable (const struct grub_install_image_target_desc *image_target)
{
@@ -225,7 +224,7 @@ grub_arm_reloc_jump24 (grub_uint32_t *target, Elf32_Addr sym_addr)
void
SUFFIX (grub_mkimage_generate_elf) (const struct grub_install_image_target_desc *image_target,
- int note, size_t appsig_size, char *sbat, char **core_img, size_t *core_size,
+ int note, char *sbat, size_t appsig_size, char **core_img, size_t *core_size,
Elf_Addr target_addr,
struct grub_mkimage_layout *layout)
{
@@ -249,7 +248,7 @@ SUFFIX (grub_mkimage_generate_elf) (const struct grub_install_image_target_desc
if (appsig_size)
{
phnum++;
- footer_size += ALIGN_UP(sizeof (struct grub_appended_signature_note) + appsig_size, 4);
+ footer_size += ALIGN_UP (sizeof (struct grub_appended_signature_note), 4);
}
if (image_target->id != IMAGE_LOONGSON_ELF)
@@ -542,29 +541,31 @@ SUFFIX (grub_mkimage_generate_elf) (const struct grub_install_image_target_desc
phdr->p_filesz = grub_host_to_target32 (note_size);
phdr->p_memsz = 0;
phdr->p_offset = grub_host_to_target32 (header_size + program_size + footer_offset);
+ footer += note_size;
+ footer_offset += note_size;
}
- if (appsig_size) {
- int note_size = ALIGN_UP(sizeof (struct grub_appended_signature_note) + appsig_size, 4);
- struct grub_appended_signature_note *note_ptr = (struct grub_appended_signature_note *)
- (elf_img + program_size + header_size + (note ? sizeof (struct grub_ieee1275_note) : 0));
+ if (appsig_size)
+ {
+ int note_size = ALIGN_UP (sizeof (struct grub_appended_signature_note) + appsig_size, 4);
+ struct grub_appended_signature_note *note_ptr = (struct grub_appended_signature_note *) footer;
- note_ptr->header.n_namesz = grub_host_to_target32 (sizeof (GRUB_APPENDED_SIGNATURE_NOTE_NAME));
- /* needs to sit at the end, so we round this up and sign some zero padding */
- note_ptr->header.n_descsz = grub_host_to_target32 (ALIGN_UP(appsig_size, 4));
- note_ptr->header.n_type = grub_host_to_target32 (GRUB_APPENDED_SIGNATURE_NOTE_TYPE);
- strcpy (note_ptr->name, GRUB_APPENDED_SIGNATURE_NOTE_NAME);
+ note_ptr->header.n_namesz = grub_host_to_target32 (sizeof (GRUB_APPENDED_SIGNATURE_NOTE_NAME));
+ /* Needs to sit at the end, so we round this up and sign some zero padding. */
+ note_ptr->header.n_descsz = grub_host_to_target32 (ALIGN_UP (appsig_size, 4));
+ note_ptr->header.n_type = grub_host_to_target32 (GRUB_APPENDED_SIGNATURE_NOTE_TYPE);
+ strcpy (note_ptr->name, GRUB_APPENDED_SIGNATURE_NOTE_NAME);
- phdr++;
- phdr->p_type = grub_host_to_target32 (PT_NOTE);
- phdr->p_flags = grub_host_to_target32 (PF_R);
- phdr->p_align = grub_host_to_target32 (image_target->voidp_sizeof);
- phdr->p_vaddr = 0;
- phdr->p_paddr = 0;
- phdr->p_filesz = grub_host_to_target32 (note_size);
- phdr->p_memsz = 0;
- phdr->p_offset = grub_host_to_target32 (header_size + program_size + (note ? sizeof (struct grub_ieee1275_note) : 0));
- }
+ phdr++;
+ phdr->p_type = grub_host_to_target32 (PT_NOTE);
+ phdr->p_flags = grub_host_to_target32 (PF_R);
+ phdr->p_align = grub_host_to_target32 (image_target->voidp_sizeof);
+ phdr->p_vaddr = 0;
+ phdr->p_paddr = 0;
+ phdr->p_filesz = grub_host_to_target32 (note_size);
+ phdr->p_memsz = 0;
+ phdr->p_offset = grub_host_to_target32 (header_size + program_size + footer_offset);
+ }
{
char *str_start = (elf_img + sizeof (*ehdr) + phnum * sizeof (*phdr)
diff --git a/util/mkimage.c b/util/mkimage.c
index cc4c79d..15cfd4b 100644
--- a/util/mkimage.c
+++ b/util/mkimage.c
@@ -883,12 +883,11 @@ void
grub_install_generate_image (const char *dir, const char *prefix,
FILE *out, const char *outname, char *mods[],
char *memdisk_path, char **pubkey_paths,
- size_t npubkeys, char **x509key_paths,
- size_t nx509keys, char *config_path,
+ size_t npubkeys, char **x509key_paths, size_t nx509keys, char *config_path,
const struct grub_install_image_target_desc *image_target,
- int note, size_t appsig_size, grub_compression_t comp,
- const char *dtb_path, const char *sbat_path,
- int disable_shim_lock, int disable_cli)
+ int note, size_t appsig_size, grub_compression_t comp, const char *dtb_path,
+ const char *sbat_path, int disable_shim_lock,
+ int disable_cli)
{
char *kernel_img, *core_img;
size_t total_module_size, core_size;
@@ -978,6 +977,9 @@ grub_install_generate_image (const char *dir, const char *prefix,
if (sbat_path != NULL && (image_target->id != IMAGE_EFI && image_target->id != IMAGE_PPC))
grub_util_error (_("SBAT data can be added only to EFI or powerpc-ieee1275 images"));
+ if (appsig_size != 0 && image_target->id != IMAGE_PPC)
+ grub_util_error (_("appended signature can be support only to powerpc-ieee1275 images"));
+
if (disable_shim_lock)
total_module_size += sizeof (struct grub_module_header);
@@ -1884,11 +1886,11 @@ grub_install_generate_image (const char *dir, const char *prefix,
else
target_addr = image_target->link_addr;
if (image_target->voidp_sizeof == 4)
- grub_mkimage_generate_elf32 (image_target, note, appsig_size, sbat, &core_img,
- &core_size, target_addr, &layout);
+ grub_mkimage_generate_elf32 (image_target, note, sbat, appsig_size, &core_img, &core_size,
+ target_addr, &layout);
else
- grub_mkimage_generate_elf64 (image_target, note, appsig_size, sbat, &core_img,
- &core_size, target_addr, &layout);
+ grub_mkimage_generate_elf64 (image_target, note, sbat, appsig_size, &core_img, &core_size,
+ target_addr, &layout);
}
break;
}
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