[v2,14/15] x86/boot: Split off PE/COFF .data section

Message ID	20230912090051.4014114-31-ardb@google.com
State	Superseded
Headers	show Return-Path: <linux-efi-owner@vger.kernel.org> Date: Tue, 12 Sep 2023 09:01:05 +0000 In-Reply-To: <20230912090051.4014114-17-ardb@google.com> Mime-Version: 1.0 References: <20230912090051.4014114-17-ardb@google.com> Message-ID: <20230912090051.4014114-31-ardb@google.com> Subject: [PATCH v2 14/15] x86/boot: Split off PE/COFF .data section From: Ard Biesheuvel <ardb@google.com> To: linux-efi@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>, Evgeniy Baskov <baskov@ispras.ru>, Borislav Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>, Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, Peter Jones <pjones@redhat.com>, Matthew Garrett <mjg59@srcf.ucam.org>, Gerd Hoffmann <kraxel@redhat.com>, Kees Cook <keescook@chromium.org>, "H. Peter Anvin" <hpa@zytor.com> Content-Type: text/plain; charset="UTF-8" Precedence: bulk
Series	x86/boot: Rework PE header generation \| expand [v2,00/15] x86/boot: Rework PE header generation [v2,01/15] x86/efi: Drop EFI stub .bss from .data section [v2,02/15] x86/efi: Disregard setup header of loaded image [v2,03/15] x86/efi: Drop alignment flags from PE section headers [v2,04/15] x86/boot: Remove the 'bugger off' message [v2,05/15] x86/boot: Omit compression buffer from PE/COFF image memory footprint [v2,06/15] x86/boot: Drop redundant code setting the root device [v2,07/15] x86/boot: Grab kernel_info offset from zoffset header directly [v2,08/15] x86/boot: Drop references to startup_64 [v2,09/15] x86/boot: Set EFI handover offset directly in header asm [v2,10/15] x86/boot: Define setup size in linker script [v2,11/15] x86/boot: Derive file size from _edata symbol [v2,12/15] x86/boot: Construct PE/COFF .text section from assembler [v2,13/15] x86/boot: Drop PE/COFF .reloc section [v2,14/15] x86/boot: Split off PE/COFF .data section [v2,15/15] x86/boot: Increase section and file alignment to 4k/512

Message ID

20230912090051.4014114-31-ardb@google.com

State

Superseded

Headers

Date: Tue, 12 Sep 2023 09:01:05 +0000
In-Reply-To: <20230912090051.4014114-17-ardb@google.com>
Mime-Version: 1.0
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Message-ID: <20230912090051.4014114-31-ardb@google.com>
Subject: [PATCH v2 14/15] x86/boot: Split off PE/COFF .data section
From: Ard Biesheuvel <ardb@google.com>
To: linux-efi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
        Evgeniy Baskov <baskov@ispras.ru>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Jones <pjones@redhat.com>,
        Matthew Garrett <mjg59@srcf.ucam.org>,
        Gerd Hoffmann <kraxel@redhat.com>,
        Kees Cook <keescook@chromium.org>,
        "H. Peter Anvin" <hpa@zytor.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Series

x86/boot: Rework PE header generation | expand

Commit Message

Ard Biesheuvel Sept. 12, 2023, 9:01 a.m. UTC

From: Ard Biesheuvel <ardb@kernel.org>

Describe the code and data of the decompressor binary using separate
.text and .data PE/COFF sections, so that we will be able to map them
using restricted permissions once we increase the section and file
alignment sufficiently. This avoids the need for memory mappings that
are writable and executable at the same time, which is something that
is best avoided for security reasons.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/x86/boot/Makefile |  2 +-
 arch/x86/boot/header.S | 19 +++++++++++++++----
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index cc04917b1ac6..3cece19b7473 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -89,7 +89,7 @@  $(obj)/vmlinux.bin: $(obj)/compressed/vmlinux FORCE
 
 SETUP_OBJS = $(addprefix $(obj)/,$(setup-y))
 
-sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_edata\|z_.*\)$$/\#define ZO_\2 0x\1/p'
+sed-zoffset := -e 's/^\([0-9a-fA-F]*\) [a-zA-Z] \(startup_32\|efi.._stub_entry\|efi\(32\)\?_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_e\?data\|z_.*\)$$/\#define ZO_\2 0x\1/p'
 
 quiet_cmd_zoffset = ZOFFSET $@
       cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 9e9641e220a7..a1f986105f00 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -75,9 +75,9 @@  optional_header:
 	.byte	0x02				# MajorLinkerVersion
 	.byte	0x14				# MinorLinkerVersion
 
-	.long	setup_size + ZO__end - 0x200	# SizeOfCode
+	.long	ZO__data			# SizeOfCode
 
-	.long	0				# SizeOfInitializedData
+	.long	ZO__end - ZO__data		# SizeOfInitializedData
 	.long	0				# SizeOfUninitializedData
 
 	.long	setup_size + ZO_efi_pe_entry	# AddressOfEntryPoint
@@ -178,9 +178,9 @@  section_table:
 	.byte	0
 	.byte	0
 	.byte	0
-	.long	ZO__end
+	.long	ZO__data
 	.long	setup_size
-	.long	ZO__edata			# Size of initialized data
+	.long	ZO__data			# Size of initialized data
 						# on disk
 	.long	setup_size
 	.long	0				# PointerToRelocations
@@ -191,6 +191,17 @@  section_table:
 		IMAGE_SCN_MEM_READ		| \
 		IMAGE_SCN_MEM_EXECUTE		# Characteristics
 
+	.ascii	".data\0\0\0"
+	.long	ZO__end - ZO__data		# VirtualSize
+	.long	setup_size + ZO__data		# VirtualAddress
+	.long	ZO__edata - ZO__data		# SizeOfRawData
+	.long	setup_size + ZO__data		# PointerToRawData
+
+	.long	0, 0, 0
+	.long	IMAGE_SCN_CNT_INITIALIZED_DATA	| \
+		IMAGE_SCN_MEM_READ		| \
+		IMAGE_SCN_MEM_WRITE		# Characteristics
+
 	.set	section_count, (. - section_table) / 40
 #endif /* CONFIG_EFI_STUB */

[v2,14/15] x86/boot: Split off PE/COFF .data section

Commit Message

Patch