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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jan Hlavac <jhlavac@redhat.com>
Date: Fri, 20 Nov 2020 23:51:47 +0100
Subject: [PATCH] grub-install: disable support for EFI platforms
For each platform, GRUB is shipped as a kernel image and a set of
modules. These files are then used by the grub-install utility to
install GRUB on a specific device. However, in order to support UEFI
Secure Boot, the resulting EFI binary must be signed by a recognized
private key. For this reason, for EFI platforms, most distributions also
ship prebuilt EFI binaries signed by a distribution-specific private
key. In this case, however, the grub-install utility should not be used
because it would overwrite the signed EFI binary.
The current fix is suboptimal because it preserves all EFI-related code.
A better solution could be to modularize the code and provide a
build-time option.
Resolves: rhbz#1737444
Signed-off-by: Jan Hlavac <jhlavac@redhat.com>
---
util/grub-install.c | 37 ++++++++++++++++---------------------
docs/grub.texi | 7 +++++++
util/grub-install.8 | 4 +++-
3 files changed, 26 insertions(+), 22 deletions(-)
diff --git a/util/grub-install.c b/util/grub-install.c
index a2bec7446cb..5babc7af551 100644
--- a/util/grub-install.c
+++ b/util/grub-install.c
@@ -899,6 +899,22 @@ main (int argc, char *argv[])
platform = grub_install_get_target (grub_install_source_directory);
+ switch (platform)
+ {
+ case GRUB_INSTALL_PLATFORM_ARM_EFI:
+ case GRUB_INSTALL_PLATFORM_ARM64_EFI:
+ case GRUB_INSTALL_PLATFORM_I386_EFI:
+ case GRUB_INSTALL_PLATFORM_IA64_EFI:
+ case GRUB_INSTALL_PLATFORM_X86_64_EFI:
+ is_efi = 1;
+ grub_util_error (_("this utility cannot be used for EFI platforms"
+ " because it does not support UEFI Secure Boot"));
+ break;
+ default:
+ is_efi = 0;
+ break;
+ }
+
{
char *platname = grub_install_get_platform_name (platform);
fprintf (stderr, _("Installing for %s platform.\n"), platname);
@@ -1011,28 +1027,7 @@ main (int argc, char *argv[])
grub_hostfs_init ();
grub_host_init ();
- switch (platform)
- {
- case GRUB_INSTALL_PLATFORM_I386_EFI:
- case GRUB_INSTALL_PLATFORM_X86_64_EFI:
- case GRUB_INSTALL_PLATFORM_ARM_EFI:
- case GRUB_INSTALL_PLATFORM_ARM64_EFI:
- case GRUB_INSTALL_PLATFORM_RISCV32_EFI:
- case GRUB_INSTALL_PLATFORM_RISCV64_EFI:
- case GRUB_INSTALL_PLATFORM_IA64_EFI:
- is_efi = 1;
- break;
- default:
- is_efi = 0;
- break;
-
- /* pacify warning. */
- case GRUB_INSTALL_PLATFORM_MAX:
- break;
- }
-
/* Find the EFI System Partition. */
-
if (is_efi)
{
grub_fs_t fs;
diff --git a/docs/grub.texi b/docs/grub.texi
index 04ed6ac1f07..4870faaa00a 100644
--- a/docs/grub.texi
+++ b/docs/grub.texi
@@ -6509,6 +6509,13 @@ grub2-install @var{install_device}
The device name @var{install_device} is an OS device name or a GRUB
device name.
+In order to support UEFI Secure Boot, the resulting GRUB EFI binary must
+be signed by a recognized private key. For this reason, for EFI
+platforms, most distributions also ship prebuilt GRUB EFI binaries
+signed by a distribution-specific private key. In this case, however,
+@command{grub2-install} should not be used because it would overwrite
+the signed EFI binary.
+
@command{grub2-install} accepts the following options:
@table @option
diff --git a/util/grub-install.8 b/util/grub-install.8
index 1db89e94b3b..811d441b16c 100644
--- a/util/grub-install.8
+++ b/util/grub-install.8
@@ -1,4 +1,4 @@
-.TH GRUB-INSTALL 1 "Wed Feb 26 2014"
+.TH GRUB-INSTALL 1 "Fri Nov 20 2020"
.SH NAME
\fBgrub-install\fR \(em Install GRUB on a device.
@@ -31,6 +31,8 @@
.SH DESCRIPTION
\fBgrub-install\fR installs GRUB onto a device. This includes copying GRUB images into the target directory (generally \fI/boot/grub\fR), and on some platforms may also include installing GRUB onto a boot sector.
+In order to support UEFI Secure Boot, the resulting GRUB EFI binary must be signed by a recognized private key. For this reason, for EFI platforms, most distributions also ship prebuilt GRUB EFI binaries signed by a distribution-specific private key. In this case, however, the \fBgrub-install\fR utility should not be used because it would overwrite the signed EFI binary.
+
.SH OPTIONS
.TP
\fB--modules\fR=\fIMODULES\fR\!