cad27ef27e
To prevent unintended modifications to the kernel text (malicious or otherwise) while running the EFI stub, describe the kernel image as two separate sections: a .text section with read-execute permissions, covering .text, .rodata and .init.text, and a .data section with read-write permissions, covering .init.data, .data and .bss. This relies on the firmware to actually take the section permission flags into account, but this is something that is currently being implemented in EDK2, which means we will likely start seeing it in the wild between one and two years from now. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
156 lines
4.8 KiB
ArmAsm
156 lines
4.8 KiB
ArmAsm
/*
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* Copyright (C) 2013 - 2017 Linaro, Ltd.
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* Copyright (C) 2013, 2014 Red Hat, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/pe.h>
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#include <linux/sizes.h>
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.macro __EFI_PE_HEADER
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.long PE_MAGIC
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coff_header:
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.short IMAGE_FILE_MACHINE_ARM64 // Machine
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.short section_count // NumberOfSections
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.long 0 // TimeDateStamp
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.long 0 // PointerToSymbolTable
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.long 0 // NumberOfSymbols
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.short section_table - optional_header // SizeOfOptionalHeader
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.short IMAGE_FILE_DEBUG_STRIPPED | \
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IMAGE_FILE_EXECUTABLE_IMAGE | \
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IMAGE_FILE_LINE_NUMS_STRIPPED // Characteristics
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optional_header:
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.short PE_OPT_MAGIC_PE32PLUS // PE32+ format
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.byte 0x02 // MajorLinkerVersion
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.byte 0x14 // MinorLinkerVersion
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.long __initdata_begin - efi_header_end // SizeOfCode
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.long __pecoff_data_size // SizeOfInitializedData
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.long 0 // SizeOfUninitializedData
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.long __efistub_entry - _head // AddressOfEntryPoint
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.long efi_header_end - _head // BaseOfCode
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extra_header_fields:
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.quad 0 // ImageBase
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.long SZ_4K // SectionAlignment
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.long PECOFF_FILE_ALIGNMENT // FileAlignment
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.short 0 // MajorOperatingSystemVersion
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.short 0 // MinorOperatingSystemVersion
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.short 0 // MajorImageVersion
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.short 0 // MinorImageVersion
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.short 0 // MajorSubsystemVersion
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.short 0 // MinorSubsystemVersion
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.long 0 // Win32VersionValue
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.long _end - _head // SizeOfImage
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// Everything before the kernel image is considered part of the header
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.long efi_header_end - _head // SizeOfHeaders
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.long 0 // CheckSum
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.short IMAGE_SUBSYSTEM_EFI_APPLICATION // Subsystem
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.short 0 // DllCharacteristics
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.quad 0 // SizeOfStackReserve
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.quad 0 // SizeOfStackCommit
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.quad 0 // SizeOfHeapReserve
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.quad 0 // SizeOfHeapCommit
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.long 0 // LoaderFlags
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.long (section_table - .) / 8 // NumberOfRvaAndSizes
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.quad 0 // ExportTable
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.quad 0 // ImportTable
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.quad 0 // ResourceTable
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.quad 0 // ExceptionTable
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.quad 0 // CertificationTable
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.quad 0 // BaseRelocationTable
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#ifdef CONFIG_DEBUG_EFI
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.long efi_debug_table - _head // DebugTable
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.long efi_debug_table_size
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#endif
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// Section table
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section_table:
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.ascii ".text\0\0\0"
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.long __initdata_begin - efi_header_end // VirtualSize
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.long efi_header_end - _head // VirtualAddress
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.long __initdata_begin - efi_header_end // SizeOfRawData
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.long efi_header_end - _head // PointerToRawData
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.long 0 // PointerToRelocations
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.long 0 // PointerToLineNumbers
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.short 0 // NumberOfRelocations
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.short 0 // NumberOfLineNumbers
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.long IMAGE_SCN_CNT_CODE | \
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IMAGE_SCN_MEM_READ | \
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IMAGE_SCN_MEM_EXECUTE // Characteristics
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.ascii ".data\0\0\0"
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.long __pecoff_data_size // VirtualSize
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.long __initdata_begin - _head // VirtualAddress
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.long __pecoff_data_rawsize // SizeOfRawData
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.long __initdata_begin - _head // PointerToRawData
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.long 0 // PointerToRelocations
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.long 0 // PointerToLineNumbers
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.short 0 // NumberOfRelocations
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.short 0 // NumberOfLineNumbers
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.long IMAGE_SCN_CNT_INITIALIZED_DATA | \
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IMAGE_SCN_MEM_READ | \
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IMAGE_SCN_MEM_WRITE // Characteristics
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.set section_count, (. - section_table) / 40
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#ifdef CONFIG_DEBUG_EFI
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/*
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* The debug table is referenced via its Relative Virtual Address (RVA),
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* which is only defined for those parts of the image that are covered
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* by a section declaration. Since this header is not covered by any
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* section, the debug table must be emitted elsewhere. So stick it in
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* the .init.rodata section instead.
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*
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* Note that the EFI debug entry itself may legally have a zero RVA,
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* which means we can simply put it right after the section headers.
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*/
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__INITRODATA
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.align 2
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efi_debug_table:
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// EFI_IMAGE_DEBUG_DIRECTORY_ENTRY
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.long 0 // Characteristics
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.long 0 // TimeDateStamp
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.short 0 // MajorVersion
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.short 0 // MinorVersion
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.long IMAGE_DEBUG_TYPE_CODEVIEW // Type
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.long efi_debug_entry_size // SizeOfData
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.long 0 // RVA
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.long efi_debug_entry - _head // FileOffset
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.set efi_debug_table_size, . - efi_debug_table
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.previous
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efi_debug_entry:
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// EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY
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.ascii "NB10" // Signature
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.long 0 // Unknown
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.long 0 // Unknown2
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.long 0 // Unknown3
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.asciz VMLINUX_PATH
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.set efi_debug_entry_size, . - efi_debug_entry
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#endif
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/*
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* EFI will load .text onwards at the 4k section alignment
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* described in the PE/COFF header. To ensure that instruction
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* sequences using an adrp and a :lo12: immediate will function
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* correctly at this alignment, we must ensure that .text is
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* placed at a 4k boundary in the Image to begin with.
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*/
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.align 12
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efi_header_end:
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.endm
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