| Message ID | 1486554947-3964-4-git-send-email-ard.biesheuvel@linaro.org |
|---|---|
| State | Accepted |
| Commit | b5f4a214b802a722091de1d94735f130dab18d1b |
| Headers | show |
| Series | arm64+ARM: efi: PE/COFF cleanup/hardening | expand |
On Wed, Feb 08, 2017 at 11:55:36AM +0000, Ard Biesheuvel wrote: > In preparation of yet another round of modifications to the PE/COFF > header, macroize it and move the definition into a separate source > file. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Thanks, Mark. > --- > arch/arm64/kernel/efi-header.S | 158 ++++++++++++++++++++ > arch/arm64/kernel/head.S | 150 +------------------ > 2 files changed, 161 insertions(+), 147 deletions(-) > > diff --git a/arch/arm64/kernel/efi-header.S b/arch/arm64/kernel/efi-header.S > new file mode 100644 > index 000000000000..9b24ce130afb > --- /dev/null > +++ b/arch/arm64/kernel/efi-header.S > @@ -0,0 +1,158 @@ > +/* > + * Copyright (C) 2013 - 2017 Linaro, Ltd. > + * Copyright (C) 2013, 2014 Red Hat, Inc. > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + */ > + > + .macro __EFI_PE_HEADER > + .ascii "PE" > + .short 0 > +coff_header: > + .short 0xaa64 // AArch64 > + .short 2 // nr_sections > + .long 0 // TimeDateStamp > + .long 0 // PointerToSymbolTable > + .long 1 // NumberOfSymbols > + .short section_table - optional_header // SizeOfOptionalHeader > + .short 0x206 // Characteristics. > + // IMAGE_FILE_DEBUG_STRIPPED | > + // IMAGE_FILE_EXECUTABLE_IMAGE | > + // IMAGE_FILE_LINE_NUMS_STRIPPED > +optional_header: > + .short 0x20b // PE32+ format > + .byte 0x02 // MajorLinkerVersion > + .byte 0x14 // MinorLinkerVersion > + .long _end - efi_header_end // SizeOfCode > + .long 0 // SizeOfInitializedData > + .long 0 // SizeOfUninitializedData > + .long __efistub_entry - _head // AddressOfEntryPoint > + .long efi_header_end - _head // BaseOfCode > + > +extra_header_fields: > + .quad 0 // ImageBase > + .long 0x1000 // SectionAlignment > + .long PECOFF_FILE_ALIGNMENT // FileAlignment > + .short 0 // MajorOperatingSystemVersion > + .short 0 // MinorOperatingSystemVersion > + .short 0 // MajorImageVersion > + .short 0 // MinorImageVersion > + .short 0 // MajorSubsystemVersion > + .short 0 // MinorSubsystemVersion > + .long 0 // Win32VersionValue > + > + .long _end - _head // SizeOfImage > + > + // Everything before the kernel image is considered part of the header > + .long efi_header_end - _head // SizeOfHeaders > + .long 0 // CheckSum > + .short 0xa // Subsystem (EFI application) > + .short 0 // DllCharacteristics > + .quad 0 // SizeOfStackReserve > + .quad 0 // SizeOfStackCommit > + .quad 0 // SizeOfHeapReserve > + .quad 0 // SizeOfHeapCommit > + .long 0 // LoaderFlags > + .long (section_table - .) / 8 // NumberOfRvaAndSizes > + > + .quad 0 // ExportTable > + .quad 0 // ImportTable > + .quad 0 // ResourceTable > + .quad 0 // ExceptionTable > + .quad 0 // CertificationTable > + .quad 0 // BaseRelocationTable > + > +#ifdef CONFIG_DEBUG_EFI > + .long efi_debug_table - _head // DebugTable > + .long efi_debug_table_size > +#endif > + > + // Section table > +section_table: > + > + /* > + * The EFI application loader requires a relocation section > + * because EFI applications must be relocatable. This is a > + * dummy section as far as we are concerned. > + */ > + .ascii ".reloc" > + .byte 0 > + .byte 0 // end of 0 padding of section name > + .long 0 > + .long 0 > + .long 0 // SizeOfRawData > + .long 0 // PointerToRawData > + .long 0 // PointerToRelocations > + .long 0 // PointerToLineNumbers > + .short 0 // NumberOfRelocations > + .short 0 // NumberOfLineNumbers > + .long 0x42100040 // Characteristics (section flags) > + > + > + .ascii ".text" > + .byte 0 > + .byte 0 > + .byte 0 // end of 0 padding of section name > + .long _end - efi_header_end // VirtualSize > + .long efi_header_end - _head // VirtualAddress > + .long _edata - efi_header_end // SizeOfRawData > + .long efi_header_end - _head // PointerToRawData > + > + .long 0 // PointerToRelocations > + .long 0 // PointerToLineNumbers > + .short 0 // NumberOfRelocations > + .short 0 // NumberOfLineNumbers > + .long 0xe0500020 // Characteristics > + > +#ifdef CONFIG_DEBUG_EFI > + /* > + * The debug table is referenced via its Relative Virtual Address (RVA), > + * which is only defined for those parts of the image that are covered > + * by a section declaration. Since this header is not covered by any > + * section, the debug table must be emitted elsewhere. So stick it in > + * the .init.rodata section instead. > + * > + * Note that the EFI debug entry itself may legally have a zero RVA, > + * which means we can simply put it right after the section headers. > + */ > + __INITRODATA > + > + .align 2 > +efi_debug_table: > + // EFI_IMAGE_DEBUG_DIRECTORY_ENTRY > + .long 0 // Characteristics > + .long 0 // TimeDateStamp > + .short 0 // MajorVersion > + .short 0 // MinorVersion > + .long 2 // Type == EFI_IMAGE_DEBUG_TYPE_CODEVIEW > + .long efi_debug_entry_size // SizeOfData > + .long 0 // RVA > + .long efi_debug_entry - _head // FileOffset > + > + .set efi_debug_table_size, . - efi_debug_table > + .previous > + > +efi_debug_entry: > + // EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY > + .ascii "NB10" // Signature > + .long 0 // Unknown > + .long 0 // Unknown2 > + .long 0 // Unknown3 > + > + .asciz VMLINUX_PATH > + > + .set efi_debug_entry_size, . - efi_debug_entry > +#endif > + > + /* > + * EFI will load .text onwards at the 4k section alignment > + * described in the PE/COFF header. To ensure that instruction > + * sequences using an adrp and a :lo12: immediate will function > + * correctly at this alignment, we must ensure that .text is > + * placed at a 4k boundary in the Image to begin with. > + */ > + .align 12 > +efi_header_end: > + .endm > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > index c6cc82ec190b..f779a7483736 100644 > --- a/arch/arm64/kernel/head.S > +++ b/arch/arm64/kernel/head.S > @@ -42,6 +42,8 @@ > #include <asm/thread_info.h> > #include <asm/virt.h> > > +#include "efi-header.S" > + > #define __PHYS_OFFSET (KERNEL_START - TEXT_OFFSET) > > #if (TEXT_OFFSET & 0xfff) != 0 > @@ -102,153 +104,7 @@ _head: > #ifdef CONFIG_EFI > .align 3 > pe_header: > - .ascii "PE" > - .short 0 > -coff_header: > - .short 0xaa64 // AArch64 > - .short 2 // nr_sections > - .long 0 // TimeDateStamp > - .long 0 // PointerToSymbolTable > - .long 1 // NumberOfSymbols > - .short section_table - optional_header // SizeOfOptionalHeader > - .short 0x206 // Characteristics. > - // IMAGE_FILE_DEBUG_STRIPPED | > - // IMAGE_FILE_EXECUTABLE_IMAGE | > - // IMAGE_FILE_LINE_NUMS_STRIPPED > -optional_header: > - .short 0x20b // PE32+ format > - .byte 0x02 // MajorLinkerVersion > - .byte 0x14 // MinorLinkerVersion > - .long _end - efi_header_end // SizeOfCode > - .long 0 // SizeOfInitializedData > - .long 0 // SizeOfUninitializedData > - .long __efistub_entry - _head // AddressOfEntryPoint > - .long efi_header_end - _head // BaseOfCode > - > -extra_header_fields: > - .quad 0 // ImageBase > - .long 0x1000 // SectionAlignment > - .long PECOFF_FILE_ALIGNMENT // FileAlignment > - .short 0 // MajorOperatingSystemVersion > - .short 0 // MinorOperatingSystemVersion > - .short 0 // MajorImageVersion > - .short 0 // MinorImageVersion > - .short 0 // MajorSubsystemVersion > - .short 0 // MinorSubsystemVersion > - .long 0 // Win32VersionValue > - > - .long _end - _head // SizeOfImage > - > - // Everything before the kernel image is considered part of the header > - .long efi_header_end - _head // SizeOfHeaders > - .long 0 // CheckSum > - .short 0xa // Subsystem (EFI application) > - .short 0 // DllCharacteristics > - .quad 0 // SizeOfStackReserve > - .quad 0 // SizeOfStackCommit > - .quad 0 // SizeOfHeapReserve > - .quad 0 // SizeOfHeapCommit > - .long 0 // LoaderFlags > - .long (section_table - .) / 8 // NumberOfRvaAndSizes > - > - .quad 0 // ExportTable > - .quad 0 // ImportTable > - .quad 0 // ResourceTable > - .quad 0 // ExceptionTable > - .quad 0 // CertificationTable > - .quad 0 // BaseRelocationTable > - > -#ifdef CONFIG_DEBUG_EFI > - .long efi_debug_table - _head // DebugTable > - .long efi_debug_table_size > -#endif > - > - // Section table > -section_table: > - > - /* > - * The EFI application loader requires a relocation section > - * because EFI applications must be relocatable. This is a > - * dummy section as far as we are concerned. > - */ > - .ascii ".reloc" > - .byte 0 > - .byte 0 // end of 0 padding of section name > - .long 0 > - .long 0 > - .long 0 // SizeOfRawData > - .long 0 // PointerToRawData > - .long 0 // PointerToRelocations > - .long 0 // PointerToLineNumbers > - .short 0 // NumberOfRelocations > - .short 0 // NumberOfLineNumbers > - .long 0x42100040 // Characteristics (section flags) > - > - > - .ascii ".text" > - .byte 0 > - .byte 0 > - .byte 0 // end of 0 padding of section name > - .long _end - efi_header_end // VirtualSize > - .long efi_header_end - _head // VirtualAddress > - .long _edata - efi_header_end // SizeOfRawData > - .long efi_header_end - _head // PointerToRawData > - > - .long 0 // PointerToRelocations (0 for executables) > - .long 0 // PointerToLineNumbers (0 for executables) > - .short 0 // NumberOfRelocations (0 for executables) > - .short 0 // NumberOfLineNumbers (0 for executables) > - .long 0xe0500020 // Characteristics (section flags) > - > -#ifdef CONFIG_DEBUG_EFI > - /* > - * The debug table is referenced via its Relative Virtual Address (RVA), > - * which is only defined for those parts of the image that are covered > - * by a section declaration. Since this header is not covered by any > - * section, the debug table must be emitted elsewhere. So stick it in > - * the .init.rodata section instead. > - * > - * Note that the EFI debug entry itself may legally have a zero RVA, > - * which means we can simply put it right after the section headers. > - */ > - __INITRODATA > - > - .align 2 > -efi_debug_table: > - // EFI_IMAGE_DEBUG_DIRECTORY_ENTRY > - .long 0 // Characteristics > - .long 0 // TimeDateStamp > - .short 0 // MajorVersion > - .short 0 // MinorVersion > - .long 2 // Type == EFI_IMAGE_DEBUG_TYPE_CODEVIEW > - .long efi_debug_entry_size // SizeOfData > - .long 0 // RVA > - .long efi_debug_entry - _head // FileOffset > - > - .set efi_debug_table_size, . - efi_debug_table > - .previous > - > -efi_debug_entry: > - // EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY > - .ascii "NB10" // Signature > - .long 0 // Unknown > - .long 0 // Unknown2 > - .long 0 // Unknown3 > - > - .asciz VMLINUX_PATH > - > - .set efi_debug_entry_size, . - efi_debug_entry > -#endif > - > - /* > - * EFI will load .text onwards at the 4k section alignment > - * described in the PE/COFF header. To ensure that instruction > - * sequences using an adrp and a :lo12: immediate will function > - * correctly at this alignment, we must ensure that .text is > - * placed at a 4k boundary in the Image to begin with. > - */ > - .align 12 > -efi_header_end: > + __EFI_PE_HEADER > #endif > > __INIT > -- > 2.7.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/arm64/kernel/efi-header.S b/arch/arm64/kernel/efi-header.S new file mode 100644 index 000000000000..9b24ce130afb --- /dev/null +++ b/arch/arm64/kernel/efi-header.S @@ -0,0 +1,158 @@ +/* + * Copyright (C) 2013 - 2017 Linaro, Ltd. + * Copyright (C) 2013, 2014 Red Hat, Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + + .macro __EFI_PE_HEADER + .ascii "PE" + .short 0 +coff_header: + .short 0xaa64 // AArch64 + .short 2 // nr_sections + .long 0 // TimeDateStamp + .long 0 // PointerToSymbolTable + .long 1 // NumberOfSymbols + .short section_table - optional_header // SizeOfOptionalHeader + .short 0x206 // Characteristics. + // IMAGE_FILE_DEBUG_STRIPPED | + // IMAGE_FILE_EXECUTABLE_IMAGE | + // IMAGE_FILE_LINE_NUMS_STRIPPED +optional_header: + .short 0x20b // PE32+ format + .byte 0x02 // MajorLinkerVersion + .byte 0x14 // MinorLinkerVersion + .long _end - efi_header_end // SizeOfCode + .long 0 // SizeOfInitializedData + .long 0 // SizeOfUninitializedData + .long __efistub_entry - _head // AddressOfEntryPoint + .long efi_header_end - _head // BaseOfCode + +extra_header_fields: + .quad 0 // ImageBase + .long 0x1000 // SectionAlignment + .long PECOFF_FILE_ALIGNMENT // FileAlignment + .short 0 // MajorOperatingSystemVersion + .short 0 // MinorOperatingSystemVersion + .short 0 // MajorImageVersion + .short 0 // MinorImageVersion + .short 0 // MajorSubsystemVersion + .short 0 // MinorSubsystemVersion + .long 0 // Win32VersionValue + + .long _end - _head // SizeOfImage + + // Everything before the kernel image is considered part of the header + .long efi_header_end - _head // SizeOfHeaders + .long 0 // CheckSum + .short 0xa // Subsystem (EFI application) + .short 0 // DllCharacteristics + .quad 0 // SizeOfStackReserve + .quad 0 // SizeOfStackCommit + .quad 0 // SizeOfHeapReserve + .quad 0 // SizeOfHeapCommit + .long 0 // LoaderFlags + .long (section_table - .) / 8 // NumberOfRvaAndSizes + + .quad 0 // ExportTable + .quad 0 // ImportTable + .quad 0 // ResourceTable + .quad 0 // ExceptionTable + .quad 0 // CertificationTable + .quad 0 // BaseRelocationTable + +#ifdef CONFIG_DEBUG_EFI + .long efi_debug_table - _head // DebugTable + .long efi_debug_table_size +#endif + + // Section table +section_table: + + /* + * The EFI application loader requires a relocation section + * because EFI applications must be relocatable. This is a + * dummy section as far as we are concerned. + */ + .ascii ".reloc" + .byte 0 + .byte 0 // end of 0 padding of section name + .long 0 + .long 0 + .long 0 // SizeOfRawData + .long 0 // PointerToRawData + .long 0 // PointerToRelocations + .long 0 // PointerToLineNumbers + .short 0 // NumberOfRelocations + .short 0 // NumberOfLineNumbers + .long 0x42100040 // Characteristics (section flags) + + + .ascii ".text" + .byte 0 + .byte 0 + .byte 0 // end of 0 padding of section name + .long _end - efi_header_end // VirtualSize + .long efi_header_end - _head // VirtualAddress + .long _edata - efi_header_end // SizeOfRawData + .long efi_header_end - _head // PointerToRawData + + .long 0 // PointerToRelocations + .long 0 // PointerToLineNumbers + .short 0 // NumberOfRelocations + .short 0 // NumberOfLineNumbers + .long 0xe0500020 // Characteristics + +#ifdef CONFIG_DEBUG_EFI + /* + * The debug table is referenced via its Relative Virtual Address (RVA), + * which is only defined for those parts of the image that are covered + * by a section declaration. Since this header is not covered by any + * section, the debug table must be emitted elsewhere. So stick it in + * the .init.rodata section instead. + * + * Note that the EFI debug entry itself may legally have a zero RVA, + * which means we can simply put it right after the section headers. + */ + __INITRODATA + + .align 2 +efi_debug_table: + // EFI_IMAGE_DEBUG_DIRECTORY_ENTRY + .long 0 // Characteristics + .long 0 // TimeDateStamp + .short 0 // MajorVersion + .short 0 // MinorVersion + .long 2 // Type == EFI_IMAGE_DEBUG_TYPE_CODEVIEW + .long efi_debug_entry_size // SizeOfData + .long 0 // RVA + .long efi_debug_entry - _head // FileOffset + + .set efi_debug_table_size, . - efi_debug_table + .previous + +efi_debug_entry: + // EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY + .ascii "NB10" // Signature + .long 0 // Unknown + .long 0 // Unknown2 + .long 0 // Unknown3 + + .asciz VMLINUX_PATH + + .set efi_debug_entry_size, . - efi_debug_entry +#endif + + /* + * EFI will load .text onwards at the 4k section alignment + * described in the PE/COFF header. To ensure that instruction + * sequences using an adrp and a :lo12: immediate will function + * correctly at this alignment, we must ensure that .text is + * placed at a 4k boundary in the Image to begin with. + */ + .align 12 +efi_header_end: + .endm diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index c6cc82ec190b..f779a7483736 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -42,6 +42,8 @@ #include <asm/thread_info.h> #include <asm/virt.h> +#include "efi-header.S" + #define __PHYS_OFFSET (KERNEL_START - TEXT_OFFSET) #if (TEXT_OFFSET & 0xfff) != 0 @@ -102,153 +104,7 @@ _head: #ifdef CONFIG_EFI .align 3 pe_header: - .ascii "PE" - .short 0 -coff_header: - .short 0xaa64 // AArch64 - .short 2 // nr_sections - .long 0 // TimeDateStamp - .long 0 // PointerToSymbolTable - .long 1 // NumberOfSymbols - .short section_table - optional_header // SizeOfOptionalHeader - .short 0x206 // Characteristics. - // IMAGE_FILE_DEBUG_STRIPPED | - // IMAGE_FILE_EXECUTABLE_IMAGE | - // IMAGE_FILE_LINE_NUMS_STRIPPED -optional_header: - .short 0x20b // PE32+ format - .byte 0x02 // MajorLinkerVersion - .byte 0x14 // MinorLinkerVersion - .long _end - efi_header_end // SizeOfCode - .long 0 // SizeOfInitializedData - .long 0 // SizeOfUninitializedData - .long __efistub_entry - _head // AddressOfEntryPoint - .long efi_header_end - _head // BaseOfCode - -extra_header_fields: - .quad 0 // ImageBase - .long 0x1000 // SectionAlignment - .long PECOFF_FILE_ALIGNMENT // FileAlignment - .short 0 // MajorOperatingSystemVersion - .short 0 // MinorOperatingSystemVersion - .short 0 // MajorImageVersion - .short 0 // MinorImageVersion - .short 0 // MajorSubsystemVersion - .short 0 // MinorSubsystemVersion - .long 0 // Win32VersionValue - - .long _end - _head // SizeOfImage - - // Everything before the kernel image is considered part of the header - .long efi_header_end - _head // SizeOfHeaders - .long 0 // CheckSum - .short 0xa // Subsystem (EFI application) - .short 0 // DllCharacteristics - .quad 0 // SizeOfStackReserve - .quad 0 // SizeOfStackCommit - .quad 0 // SizeOfHeapReserve - .quad 0 // SizeOfHeapCommit - .long 0 // LoaderFlags - .long (section_table - .) / 8 // NumberOfRvaAndSizes - - .quad 0 // ExportTable - .quad 0 // ImportTable - .quad 0 // ResourceTable - .quad 0 // ExceptionTable - .quad 0 // CertificationTable - .quad 0 // BaseRelocationTable - -#ifdef CONFIG_DEBUG_EFI - .long efi_debug_table - _head // DebugTable - .long efi_debug_table_size -#endif - - // Section table -section_table: - - /* - * The EFI application loader requires a relocation section - * because EFI applications must be relocatable. This is a - * dummy section as far as we are concerned. - */ - .ascii ".reloc" - .byte 0 - .byte 0 // end of 0 padding of section name - .long 0 - .long 0 - .long 0 // SizeOfRawData - .long 0 // PointerToRawData - .long 0 // PointerToRelocations - .long 0 // PointerToLineNumbers - .short 0 // NumberOfRelocations - .short 0 // NumberOfLineNumbers - .long 0x42100040 // Characteristics (section flags) - - - .ascii ".text" - .byte 0 - .byte 0 - .byte 0 // end of 0 padding of section name - .long _end - efi_header_end // VirtualSize - .long efi_header_end - _head // VirtualAddress - .long _edata - efi_header_end // SizeOfRawData - .long efi_header_end - _head // PointerToRawData - - .long 0 // PointerToRelocations (0 for executables) - .long 0 // PointerToLineNumbers (0 for executables) - .short 0 // NumberOfRelocations (0 for executables) - .short 0 // NumberOfLineNumbers (0 for executables) - .long 0xe0500020 // Characteristics (section flags) - -#ifdef CONFIG_DEBUG_EFI - /* - * The debug table is referenced via its Relative Virtual Address (RVA), - * which is only defined for those parts of the image that are covered - * by a section declaration. Since this header is not covered by any - * section, the debug table must be emitted elsewhere. So stick it in - * the .init.rodata section instead. - * - * Note that the EFI debug entry itself may legally have a zero RVA, - * which means we can simply put it right after the section headers. - */ - __INITRODATA - - .align 2 -efi_debug_table: - // EFI_IMAGE_DEBUG_DIRECTORY_ENTRY - .long 0 // Characteristics - .long 0 // TimeDateStamp - .short 0 // MajorVersion - .short 0 // MinorVersion - .long 2 // Type == EFI_IMAGE_DEBUG_TYPE_CODEVIEW - .long efi_debug_entry_size // SizeOfData - .long 0 // RVA - .long efi_debug_entry - _head // FileOffset - - .set efi_debug_table_size, . - efi_debug_table - .previous - -efi_debug_entry: - // EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY - .ascii "NB10" // Signature - .long 0 // Unknown - .long 0 // Unknown2 - .long 0 // Unknown3 - - .asciz VMLINUX_PATH - - .set efi_debug_entry_size, . - efi_debug_entry -#endif - - /* - * EFI will load .text onwards at the 4k section alignment - * described in the PE/COFF header. To ensure that instruction - * sequences using an adrp and a :lo12: immediate will function - * correctly at this alignment, we must ensure that .text is - * placed at a 4k boundary in the Image to begin with. - */ - .align 12 -efi_header_end: + __EFI_PE_HEADER #endif __INIT
In preparation of yet another round of modifications to the PE/COFF header, macroize it and move the definition into a separate source file. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- arch/arm64/kernel/efi-header.S | 158 ++++++++++++++++++++ arch/arm64/kernel/head.S | 150 +------------------ 2 files changed, 161 insertions(+), 147 deletions(-) -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html