Message-ID: <8E544119-66B8-4482-BBE9-68B6C7A3AAE9@zytor.com>
Date:   Thu, 13 Apr 2017 15:21:20 -0700
From:   hpa@...or.com
To:     Gary Lin <glin@...e.com>, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>
CC:     x86@...nel.org, linux-kernel@...r.kernel.org,
        linux-efi@...r.kernel.org,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <mmarek@...e.com>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Joey Lee <jlee@...e.com>, Vojtech Pavlik <vojtech@...e.cz>
Subject: Re: [RFC PATCH] x86: Config options to assign versions in the PE-COFF header

On April 11, 2017 3:20:41 AM PDT, Gary Lin <glin@...e.com> wrote:
>This commit adds the new config options to allow the user to modify the
>following fields in the PE-COFF header.
>
>UINT16 MajorOperatingSystemVersion
>UINT16 MinorOperatingSystemVersion
>UINT16 MajorImageVersion
>UINT16 MinorImageVersion
>
>Those fields are mainly for the executables or libraries in Windows NT
>or higher to specify the minimum supported Windows version and the
>version of the image itself.
>
>Given the fact that those fields are ignored in UEFI, we can safely
>reuse
>those fields for other purposes, e.g. Security Version(*).
>
>(*) https://github.com/lcp/shim/wiki/Security-Version
>
>Cc: Thomas Gleixner <tglx@...utronix.de>
>Cc: Ingo Molnar <mingo@...hat.com>
>Cc: "H. Peter Anvin" <hpa@...or.com>
>Cc: Masahiro Yamada <yamada.masahiro@...ionext.com>
>Cc: Michal Marek <mmarek@...e.com>
>Cc: Matt Fleming <matt@...eblueprint.co.uk>
>Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
>Cc: Joey Lee <jlee@...e.com>
>Cc: Vojtech Pavlik <vojtech@...e.cz>
>Signed-off-by: Gary Lin <glin@...e.com>
>Tested-by: Joey Lee <jlee@...e.com>
>---
> arch/x86/Kconfig       |  24 +++++++
> arch/x86/boot/Makefile |  10 +++
>scripts/efiversion.pl  | 192
>+++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 226 insertions(+)
> create mode 100755 scripts/efiversion.pl
>
>diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>index 5bbdef151805..f281c0ff3ff6 100644
>--- a/arch/x86/Kconfig
>+++ b/arch/x86/Kconfig
>@@ -1803,6 +1803,30 @@ config EFI_STUB
> 
> 	  See Documentation/efi-stub.txt for more information.
> 
>+config EFI_MAJOR_OS_VERSION
>+	hex "EFI Major OS Version"
>+	range 0x0 0xFFFF
>+	default "0x0"
>+	depends on EFI_STUB
>+
>+config EFI_MINOR_OS_VERSION
>+	hex "EFI Minor OS Version"
>+	range 0x0 0xFFFF
>+	default "0x0"
>+	depends on EFI_STUB
>+
>+config EFI_MAJOR_IMAGE_VERSION
>+	hex "EFI Major Image Version"
>+	range 0x0 0xFFFF
>+	default "0x0"
>+	depends on EFI_STUB
>+
>+config EFI_MINOR_IMAGE_VERSION
>+	hex "EFI Minor Image Version"
>+	range 0x0 0xFFFF
>+	default "0x0"
>+	depends on EFI_STUB
>+
> config EFI_MIXED
> 	bool "EFI mixed-mode support"
> 	depends on EFI_STUB && X86_64
>diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
>index 0d810fb15eac..b9de8b50f32a 100644
>--- a/arch/x86/boot/Makefile
>+++ b/arch/x86/boot/Makefile
>@@ -76,8 +76,18 @@ quiet_cmd_image = BUILD   $@
> cmd_image = $(obj)/tools/build $(obj)/setup.bin $(obj)/vmlinux.bin \
> 			       $(obj)/zoffset.h $@
> 
>+cmd_efiversion = scripts/efiversion.pl \
>+			--major-os=$(CONFIG_EFI_MAJOR_OS_VERSION) \
>+			--minor-os=$(CONFIG_EFI_MINOR_OS_VERSION) \
>+			--major-image=$(CONFIG_EFI_MAJOR_IMAGE_VERSION) \
>+			--minor-image=$(CONFIG_EFI_MINOR_IMAGE_VERSION) \
>+			$@
>+
>$(obj)/bzImage: $(obj)/setup.bin $(obj)/vmlinux.bin $(obj)/tools/build
>FORCE
> 	$(call if_changed,image)
>+ifeq ($(CONFIG_EFI_STUB),y)
>+	$(call if_changed,efiversion,$@)
>+endif
> 	@echo 'Kernel: $@ is ready' ' (#'`cat .version`')'
> 
> OBJCOPYFLAGS_vmlinux.bin := -O binary -R .note -R .comment -S
>diff --git a/scripts/efiversion.pl b/scripts/efiversion.pl
>new file mode 100755
>index 000000000000..fe730d10638a
>--- /dev/null
>+++ b/scripts/efiversion.pl
>@@ -0,0 +1,192 @@
>+#!/usr/bin/perl
>+
>+=head1 efiversion.pl
>+
>+efiversion.pl - show or modify the version fields in the EFI image
>+
>+=head1 SYNOPSIS
>+
>+efiversion.pl [OPTIONS] FILE
>+
>+=head1 OPTIONS
>+
>+=over 4
>+
>+=item B<--major-os=NUMBER>
>+
>+assign the major OS version
>+
>+=item B<--minor-os=NUMBER>
>+
>+assign the minor OS version
>+
>+=item B<--major-image=NUMBER>
>+
>+assign the major image version
>+
>+=item B<--minor-image=NUMBER>
>+
>+assign the minor image version
>+
>+=item B<--help, -h>
>+
>+print help
>+
>+=back
>+
>+=head1 DESCRIPTION
>+
>+A script to modify the version fields in the header of the EFI image
>+
>+Show the versions:
>+$ efiversion.pl sample.efi
>+
>+Modify the versions:
>+$ efiversion.pl --major-os=1 --minor-os=2 sample.efi
>+
>+=cut
>+
>+use strict;
>+use warnings;
>+use FileHandle;
>+use Getopt::Long;
>+Getopt::Long::Configure("no_ignore_case");
>+
>+my %options;
>+
>+sub usage($) {
>+	my $r = shift;
>+	eval "use Pod::Usage; pod2usage($r);";
>+	if ($@) {
>+		die "cannot display help, install perl(Pod::Usage)\n";
>+	}
>+}
>+
>+my $options;
>+my $major_os = '';
>+my $minor_os = '';
>+my $major_image = '';
>+my $minor_image = '';
>+my $help = '';
>+my $overwrite = '';
>+
>+GetOptions(
>+	"major-os=o" => \$major_os,
>+	"minor-os=o" => \$minor_os,
>+	"major-image=o" => \$major_image,
>+	"minor-image=o" => \$minor_image,
>+	"help|h" => \$help,
>+) or usage(1);
>+
>+usage(1) unless @ARGV;
>+usage(0) if ($help);
>+
>+sub not_ushort($)
>+{
>+	my ($number) = @_;
>+
>+	return 0 unless $number;
>+	return 1 if ($number < 0 or $number > 0xFFFF);
>+
>+	$overwrite = "y";
>+
>+	return 0;
>+}
>+
>+sub check_args
>+{
>+	return 0 if not_ushort($major_os);
>+	return 0 if not_ushort($minor_os);
>+	return 0 if not_ushort($major_image);
>+	return 0 if not_ushort($minor_image);
>+	return 1;
>+}
>+
>+sub read_file($)
>+{
>+	my ($file) = @_;
>+	my $contents;
>+	my $len;
>+
>+	open(FD, "<$file") || die $file;
>+	binmode FD;
>+	my @st = stat(FD);
>+	die $file if (!@st);
>+	$len = read(FD, $contents, $st[7]) || die $file;
>+	close(FD) || die $file;
>+	die "$file: Wanted length ", $st[7], ", got ", $len, "\n"
>+		if ($len != $st[7]);
>+	return $contents;
>+}
>+
>+sub get_signature_offset($)
>+{
>+	my ($image) = @_;
>+
>+	# e_magic must be 'M''Z'
>+	my ($e_magic) = unpack("n", substr($image, 0, 2));
>+	die "not a EFI Image\n" unless ($e_magic == 0x4D5A);
>+
>+	# Get the offset to the PE signature
>+	my ($e_lfanew) = unpack("V", substr($image, 0x3C, 4));
>+
>+	# Match Signature 'P''E''\0''\0'
>+	my ($Signature) = unpack("N", substr($image, $e_lfanew, 4));
>+	die "not a PE Image\n" unless ($Signature == 0x50450000);
>+
>+	return $e_lfanew;
>+}
>+
>+sub write_file($)
>+{
>+	my ($file, $contents) = @_;
>+
>+	open(FD, ">$file") || die $file;
>+	binmode FD;
>+	print FD $contents;
>+	close(FD) || die $file;
>+}
>+
>+sub set_version($)
>+{
>+	my ($image_ptr, $offset, $value) = @_;
>+	my $packed = pack("v", $value);
>+	substr($$image_ptr, $offset, 2, $packed);
>+}
>+
>+die "invalid arguments\n" unless check_args;
>+
>+my ($file) = @ARGV;
>+my $pe_image = read_file($file) if ($file);
>+my $e_lfanew = get_signature_offset($pe_image);
>+
>+# [PE Signature][COFF File Header][Optional Header]
>+#     4 bytes        20 bytes
>+#
>+# The offset of MajorOperatingSystemVersion in the Optional Header: 40
>+#
>+# The file offset of MajorOperatingSystemVersion: $e_lfanew + 24 + 40
>+#
>+# Our targets:
>+#   UINT16  MajorOperatingSystemVersion;
>+#   UINT16  MinorOperatingSystemVersion;
>+#   UINT16  MajorImageVersion;
>+#   UINT16  MinorImageVersion;
>+my $os_offset = $e_lfanew + 64;
>+
>+if ($overwrite) {
>+	# Write the file
>+	&set_version(\$pe_image, $os_offset,     $major_os)     if
>($major_os);
>+	&set_version(\$pe_image, $os_offset + 2, $minor_os)     if
>($minor_os);
>+	&set_version(\$pe_image, $os_offset + 4, $major_image)  if
>($major_image);
>+	&set_version(\$pe_image, $os_offset + 6, $minor_image)  if
>($minor_image);
>+	&write_file($file, $pe_image);
>+} else {
>+	# Get the versions
>+	(my @versions) = unpack("v6", substr($pe_image, $os_offset, 12));
>+
>+	printf "MajorOperatingSystemVersion\t0x%X\n", $versions[0];
>+	printf "MinorOperatingSystemVersion\t0x%X\n", $versions[1];
>+	printf "MajorImageVersion\t\t0x%X\n",         $versions[2];
>+	printf "MinorImageVersion\t\t0x%X\n",         $versions[3];
>+}

Reusing PECOFF fields seems doubleplusunsafe: we don't own those fields, the UEFI forum does.  It would make a lot more sense to add these fields to the bzImage header directly or indirectly (via a pointer), the latter would be more economical since the bzImage header size is bounded.

We could even define it as a pointer to a "security information header" with its own size field, so it can be grown in the future as needed.
-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.

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