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linux/drivers/firmware/efi/libstub/zboot-header.S

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efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/pe.h>
#ifdef CONFIG_64BIT
.set .Lextra_characteristics, 0x0
include: pe.h: Fix PE definitions * Rename constants to their standard PE names: - MZ_MAGIC -> IMAGE_DOS_SIGNATURE - PE_MAGIC -> IMAGE_NT_SIGNATURE - PE_OPT_MAGIC_PE32_ROM -> IMAGE_ROM_OPTIONAL_HDR_MAGIC - PE_OPT_MAGIC_PE32 -> IMAGE_NT_OPTIONAL_HDR32_MAGIC - PE_OPT_MAGIC_PE32PLUS -> IMAGE_NT_OPTIONAL_HDR64_MAGIC - IMAGE_DLL_CHARACTERISTICS_NX_COMPAT -> IMAGE_DLLCHARACTERISTICS_NX_COMPAT * Import constants and their description from readpe and file projects which contains current up-to-date information: - IMAGE_FILE_MACHINE_* - IMAGE_FILE_* - IMAGE_SUBSYSTEM_* - IMAGE_DLLCHARACTERISTICS_* - IMAGE_DLLCHARACTERISTICS_EX_* - IMAGE_DEBUG_TYPE_* * Add missing IMAGE_SCN_* constants and update their incorrect description * Fix incorrect value of IMAGE_SCN_MEM_PURGEABLE constant * Add description for win32_version and loader_flags PE fields Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-05-04 20:22:44 +02:00
.set .Lpe_opt_magic, IMAGE_NT_OPTIONAL_HDR64_MAGIC
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
#else
.set .Lextra_characteristics, IMAGE_FILE_32BIT_MACHINE
include: pe.h: Fix PE definitions * Rename constants to their standard PE names: - MZ_MAGIC -> IMAGE_DOS_SIGNATURE - PE_MAGIC -> IMAGE_NT_SIGNATURE - PE_OPT_MAGIC_PE32_ROM -> IMAGE_ROM_OPTIONAL_HDR_MAGIC - PE_OPT_MAGIC_PE32 -> IMAGE_NT_OPTIONAL_HDR32_MAGIC - PE_OPT_MAGIC_PE32PLUS -> IMAGE_NT_OPTIONAL_HDR64_MAGIC - IMAGE_DLL_CHARACTERISTICS_NX_COMPAT -> IMAGE_DLLCHARACTERISTICS_NX_COMPAT * Import constants and their description from readpe and file projects which contains current up-to-date information: - IMAGE_FILE_MACHINE_* - IMAGE_FILE_* - IMAGE_SUBSYSTEM_* - IMAGE_DLLCHARACTERISTICS_* - IMAGE_DLLCHARACTERISTICS_EX_* - IMAGE_DEBUG_TYPE_* * Add missing IMAGE_SCN_* constants and update their incorrect description * Fix incorrect value of IMAGE_SCN_MEM_PURGEABLE constant * Add description for win32_version and loader_flags PE fields Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-05-04 20:22:44 +02:00
.set .Lpe_opt_magic, IMAGE_NT_OPTIONAL_HDR32_MAGIC
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
#endif
.section ".head", "a"
.globl __efistub_efi_zboot_header
__efistub_efi_zboot_header:
.Ldoshdr:
include: pe.h: Fix PE definitions * Rename constants to their standard PE names: - MZ_MAGIC -> IMAGE_DOS_SIGNATURE - PE_MAGIC -> IMAGE_NT_SIGNATURE - PE_OPT_MAGIC_PE32_ROM -> IMAGE_ROM_OPTIONAL_HDR_MAGIC - PE_OPT_MAGIC_PE32 -> IMAGE_NT_OPTIONAL_HDR32_MAGIC - PE_OPT_MAGIC_PE32PLUS -> IMAGE_NT_OPTIONAL_HDR64_MAGIC - IMAGE_DLL_CHARACTERISTICS_NX_COMPAT -> IMAGE_DLLCHARACTERISTICS_NX_COMPAT * Import constants and their description from readpe and file projects which contains current up-to-date information: - IMAGE_FILE_MACHINE_* - IMAGE_FILE_* - IMAGE_SUBSYSTEM_* - IMAGE_DLLCHARACTERISTICS_* - IMAGE_DLLCHARACTERISTICS_EX_* - IMAGE_DEBUG_TYPE_* * Add missing IMAGE_SCN_* constants and update their incorrect description * Fix incorrect value of IMAGE_SCN_MEM_PURGEABLE constant * Add description for win32_version and loader_flags PE fields Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-05-04 20:22:44 +02:00
.long IMAGE_DOS_SIGNATURE
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
.ascii "zimg" // image type
.long __efistub__gzdata_start - .Ldoshdr // payload offset
efi/zboot: Add BSS padding before compression We don't really care about the size of the decompressed image - what matters is how much space needs to be allocated for the image to execute, and this includes space for BSS that is not part of the loadable image and so it is not accounted for in the decompressed size. So let's add some zero padding to the end of the image: this compresses well, and it ensures that BSS is accounted for, and as a bonus, it will be zeroed before launching the image. Since all architectures that implement support for EFI zboot carry this value in the header in the same location, we can just grab it from the binary that is being compressed. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2023-04-18 15:49:50 +02:00
.long __efistub__gzdata_size - ZBOOT_SIZE_LEN // payload size
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
.long 0, 0 // reserved
.asciz COMP_TYPE // compression type
efi: Put Linux specific magic number in the DOS header GRUB currently relies on the magic number in the image header of ARM and arm64 EFI kernel images to decide whether or not the image in question is a bootable kernel. However, the purpose of the magic number is to identify the image as one that implements the bare metal boot protocol, and so GRUB, which only does EFI boot, is limited unnecessarily to booting images that could potentially be booted in a non-EFI manner as well. This is problematic for the new zboot decompressor image format, as it can only boot in EFI mode, and must therefore not use the bare metal boot magic number in its header. For this reason, the strict magic number was dropped from GRUB, to permit essentially any kind of EFI executable to be booted via the 'linux' command, blurring the line between the linux loader and the chainloader. So let's use the same field in the DOS header that RISC-V and arm64 already use for their 'bare metal' magic numbers to store a 'generic Linux kernel' magic number, which can be used to identify bootable kernel images in PE format which don't necessarily implement a bare metal boot protocol in the same binary. Note that, in the context of EFI, the MS-DOS header is only described in terms of the fields that it shares with the hybrid PE/COFF image format, (i.e., the MS-DOS EXE magic number at offset #0 and the PE header offset at byte offset #0x3c). Since we aim for compatibility with EFI only, and not with MS-DOS or MS-Windows, we can use the remaining space in the MS-DOS header however we want. Let's set the generic magic number for x86 images as well: existing bootloaders already have their own methods to identify x86 Linux images that can be booted in a non-EFI manner, and having the magic number in place there will ease any future transitions in loader implementations to merge the x86 and non-x86 EFI boot paths. Note that 32-bit ARM already uses the same location in the header for a different purpose, but the ARM support is already widely implemented and the EFI zboot decompressor is not available on ARM anyway, so we just disregard it here. Acked-by: Leif Lindholm <quic_llindhol@quicinc.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-11-09 15:16:11 +01:00
.org .Ldoshdr + 0x38
.long LINUX_PE_MAGIC
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
.long .Lpehdr - .Ldoshdr // PE header offset
.Lpehdr:
include: pe.h: Fix PE definitions * Rename constants to their standard PE names: - MZ_MAGIC -> IMAGE_DOS_SIGNATURE - PE_MAGIC -> IMAGE_NT_SIGNATURE - PE_OPT_MAGIC_PE32_ROM -> IMAGE_ROM_OPTIONAL_HDR_MAGIC - PE_OPT_MAGIC_PE32 -> IMAGE_NT_OPTIONAL_HDR32_MAGIC - PE_OPT_MAGIC_PE32PLUS -> IMAGE_NT_OPTIONAL_HDR64_MAGIC - IMAGE_DLL_CHARACTERISTICS_NX_COMPAT -> IMAGE_DLLCHARACTERISTICS_NX_COMPAT * Import constants and their description from readpe and file projects which contains current up-to-date information: - IMAGE_FILE_MACHINE_* - IMAGE_FILE_* - IMAGE_SUBSYSTEM_* - IMAGE_DLLCHARACTERISTICS_* - IMAGE_DLLCHARACTERISTICS_EX_* - IMAGE_DEBUG_TYPE_* * Add missing IMAGE_SCN_* constants and update their incorrect description * Fix incorrect value of IMAGE_SCN_MEM_PURGEABLE constant * Add description for win32_version and loader_flags PE fields Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-05-04 20:22:44 +02:00
.long IMAGE_NT_SIGNATURE
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
.short MACHINE_TYPE
.short .Lsection_count
.long 0
.long 0
.long 0
.short .Lsection_table - .Loptional_header
.short IMAGE_FILE_DEBUG_STRIPPED | \
IMAGE_FILE_EXECUTABLE_IMAGE | \
IMAGE_FILE_LINE_NUMS_STRIPPED |\
.Lextra_characteristics
.Loptional_header:
.short .Lpe_opt_magic
.byte 0, 0
.long _etext - .Lefi_header_end
.long __data_size
.long 0
.long __efistub_efi_zboot_entry - .Ldoshdr
.long .Lefi_header_end - .Ldoshdr
#ifdef CONFIG_64BIT
.quad 0
#else
.long _etext - .Ldoshdr, 0x0
#endif
.long 4096
.long 512
.short 0, 0
.short LINUX_EFISTUB_MAJOR_VERSION // MajorImageVersion
.short LINUX_EFISTUB_MINOR_VERSION // MinorImageVersion
.short 0, 0
.long 0
.long _end - .Ldoshdr
.long .Lefi_header_end - .Ldoshdr
.long 0
.short IMAGE_SUBSYSTEM_EFI_APPLICATION
include: pe.h: Fix PE definitions * Rename constants to their standard PE names: - MZ_MAGIC -> IMAGE_DOS_SIGNATURE - PE_MAGIC -> IMAGE_NT_SIGNATURE - PE_OPT_MAGIC_PE32_ROM -> IMAGE_ROM_OPTIONAL_HDR_MAGIC - PE_OPT_MAGIC_PE32 -> IMAGE_NT_OPTIONAL_HDR32_MAGIC - PE_OPT_MAGIC_PE32PLUS -> IMAGE_NT_OPTIONAL_HDR64_MAGIC - IMAGE_DLL_CHARACTERISTICS_NX_COMPAT -> IMAGE_DLLCHARACTERISTICS_NX_COMPAT * Import constants and their description from readpe and file projects which contains current up-to-date information: - IMAGE_FILE_MACHINE_* - IMAGE_FILE_* - IMAGE_SUBSYSTEM_* - IMAGE_DLLCHARACTERISTICS_* - IMAGE_DLLCHARACTERISTICS_EX_* - IMAGE_DEBUG_TYPE_* * Add missing IMAGE_SCN_* constants and update their incorrect description * Fix incorrect value of IMAGE_SCN_MEM_PURGEABLE constant * Add description for win32_version and loader_flags PE fields Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-05-04 20:22:44 +02:00
.short IMAGE_DLLCHARACTERISTICS_NX_COMPAT
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
#ifdef CONFIG_64BIT
.quad 0, 0, 0, 0
#else
.long 0, 0, 0, 0
#endif
.long 0
.long (.Lsection_table - .) / 8
.quad 0 // ExportTable
.quad 0 // ImportTable
.quad 0 // ResourceTable
.quad 0 // ExceptionTable
.quad 0 // CertificationTable
.quad 0 // BaseRelocationTable
efi/zboot: Set forward edge CFI compat header flag if supported Add some plumbing to the zboot EFI header generation to set the newly introduced DllCharacteristicsEx flag associated with forward edge CFI enforcement instructions (BTI on arm64, IBT on x86) x86 does not currently uses the zboot infrastructure, so let's wire it up only for arm64. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2023-04-18 15:49:51 +02:00
#if defined(PE_DLL_CHAR_EX) || defined(CONFIG_DEBUG_EFI)
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
.long .Lefi_debug_table - .Ldoshdr // DebugTable
.long .Lefi_debug_table_size
efi/zboot: Set forward edge CFI compat header flag if supported Add some plumbing to the zboot EFI header generation to set the newly introduced DllCharacteristicsEx flag associated with forward edge CFI enforcement instructions (BTI on arm64, IBT on x86) x86 does not currently uses the zboot infrastructure, so let's wire it up only for arm64. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2023-04-18 15:49:51 +02:00
.section ".rodata", "a"
.p2align 2
.Lefi_debug_table:
// EFI_IMAGE_DEBUG_DIRECTORY_ENTRY[]
#ifdef PE_DLL_CHAR_EX
.long 0 // Characteristics
.long 0 // TimeDateStamp
.short 0 // MajorVersion
.short 0 // MinorVersion
.long IMAGE_DEBUG_TYPE_EX_DLLCHARACTERISTICS // Type
.long 4 // SizeOfData
.long 0 // RVA
.long .Lefi_dll_characteristics_ex - .Ldoshdr // FileOffset
#endif
#ifdef CONFIG_DEBUG_EFI
.long 0 // Characteristics
.long 0 // TimeDateStamp
.short 0 // MajorVersion
.short 0 // MinorVersion
.long IMAGE_DEBUG_TYPE_CODEVIEW // Type
.long .Lefi_debug_entry_size // SizeOfData
.long 0 // RVA
.long .Lefi_debug_entry - .Ldoshdr // FileOffset
#endif
.set .Lefi_debug_table_size, . - .Lefi_debug_table
.previous
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
#endif
.Lsection_table:
.ascii ".text\0\0\0"
.long _etext - .Lefi_header_end
.long .Lefi_header_end - .Ldoshdr
.long _etext - .Lefi_header_end
.long .Lefi_header_end - .Ldoshdr
.long 0, 0
.short 0, 0
.long IMAGE_SCN_CNT_CODE | \
IMAGE_SCN_MEM_READ | \
IMAGE_SCN_MEM_EXECUTE
efi: zboot specific mechanism for embedding SBAT section SBAT is a mechanism which improves SecureBoot revocations of UEFI binaries by introducing a generation-based technique. Compromised or vulnerable UEFI binaries can be prevented from booting by bumping the minimal required generation for the specific component in the bootloader. More information on the SBAT can be obtained here: https://github.com/rhboot/shim/blob/main/SBAT.md Upstream Linux kernel does not currently participate in any way in SBAT as there's no existing policy in how SBAT generation number should be defined. Keep the status quo and provide a mechanism for distro vendors and anyone else who signs their kernel for SecureBoot to include their own SBAT data. This leaves the decision on the policy to the vendor. Basically, each distro implementing SecureBoot today, will have an option to inject their own SBAT data during kernel build and before it gets signed by their SecureBoot CA. Different distro do not need to agree on the common SBAT component names or generation numbers as each distro ships its own 'shim' with their own 'vendor_cert'/'vendor_db' Implement support for embedding SBAT data for architectures using zboot (arm64, loongarch, riscv). Put '.sbat' section in between '.data' and '.text' as the former also covers '.bss' and thus must be the last one. Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-05-13 14:58:07 +02:00
#ifdef CONFIG_EFI_SBAT
.ascii ".sbat\0\0\0"
.long __sbat_size
.long _sbat - .Ldoshdr
.long __sbat_size
.long _sbat - .Ldoshdr
.long 0, 0
.short 0, 0
.long IMAGE_SCN_CNT_INITIALIZED_DATA | \
IMAGE_SCN_MEM_READ | \
IMAGE_SCN_MEM_DISCARDABLE
.pushsection ".sbat", "a", @progbits
.incbin CONFIG_EFI_SBAT_FILE
.popsection
#endif
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
.ascii ".data\0\0\0"
.long __data_size
efi: zboot specific mechanism for embedding SBAT section SBAT is a mechanism which improves SecureBoot revocations of UEFI binaries by introducing a generation-based technique. Compromised or vulnerable UEFI binaries can be prevented from booting by bumping the minimal required generation for the specific component in the bootloader. More information on the SBAT can be obtained here: https://github.com/rhboot/shim/blob/main/SBAT.md Upstream Linux kernel does not currently participate in any way in SBAT as there's no existing policy in how SBAT generation number should be defined. Keep the status quo and provide a mechanism for distro vendors and anyone else who signs their kernel for SecureBoot to include their own SBAT data. This leaves the decision on the policy to the vendor. Basically, each distro implementing SecureBoot today, will have an option to inject their own SBAT data during kernel build and before it gets signed by their SecureBoot CA. Different distro do not need to agree on the common SBAT component names or generation numbers as each distro ships its own 'shim' with their own 'vendor_cert'/'vendor_db' Implement support for embedding SBAT data for architectures using zboot (arm64, loongarch, riscv). Put '.sbat' section in between '.data' and '.text' as the former also covers '.bss' and thus must be the last one. Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-05-13 14:58:07 +02:00
.long _data - .Ldoshdr
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
.long __data_rawsize
efi: zboot specific mechanism for embedding SBAT section SBAT is a mechanism which improves SecureBoot revocations of UEFI binaries by introducing a generation-based technique. Compromised or vulnerable UEFI binaries can be prevented from booting by bumping the minimal required generation for the specific component in the bootloader. More information on the SBAT can be obtained here: https://github.com/rhboot/shim/blob/main/SBAT.md Upstream Linux kernel does not currently participate in any way in SBAT as there's no existing policy in how SBAT generation number should be defined. Keep the status quo and provide a mechanism for distro vendors and anyone else who signs their kernel for SecureBoot to include their own SBAT data. This leaves the decision on the policy to the vendor. Basically, each distro implementing SecureBoot today, will have an option to inject their own SBAT data during kernel build and before it gets signed by their SecureBoot CA. Different distro do not need to agree on the common SBAT component names or generation numbers as each distro ships its own 'shim' with their own 'vendor_cert'/'vendor_db' Implement support for embedding SBAT data for architectures using zboot (arm64, loongarch, riscv). Put '.sbat' section in between '.data' and '.text' as the former also covers '.bss' and thus must be the last one. Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2025-05-13 14:58:07 +02:00
.long _data - .Ldoshdr
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
.long 0, 0
.short 0, 0
.long IMAGE_SCN_CNT_INITIALIZED_DATA | \
IMAGE_SCN_MEM_READ | \
IMAGE_SCN_MEM_WRITE
.set .Lsection_count, (. - .Lsection_table) / 40
efi/zboot: Set forward edge CFI compat header flag if supported Add some plumbing to the zboot EFI header generation to set the newly introduced DllCharacteristicsEx flag associated with forward edge CFI enforcement instructions (BTI on arm64, IBT on x86) x86 does not currently uses the zboot infrastructure, so let's wire it up only for arm64. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2023-04-18 15:49:51 +02:00
#ifdef PE_DLL_CHAR_EX
.Lefi_dll_characteristics_ex:
.long PE_DLL_CHAR_EX
#endif
efi/libstub: implement generic EFI zboot Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2022-05-02 01:08:16 +02:00
#ifdef CONFIG_DEBUG_EFI
.Lefi_debug_entry:
// EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY
.ascii "NB10" // Signature
.long 0 // Unknown
.long 0 // Unknown2
.long 0 // Unknown3
.asciz ZBOOT_EFI_PATH
.set .Lefi_debug_entry_size, . - .Lefi_debug_entry
#endif
.p2align 12
.Lefi_header_end:
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