Re: [PATCH 14/16] x86/build: Make generated PE more spec compliant

From: Ard Biesheuvel
Date: Wed Oct 19 2022 - 03:39:40 EST

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On Tue, 6 Sept 2022 at 12:42, Evgeniy Baskov <baskov@xxxxxxxxx> wrote:
>
> Currently kernel image is not fully compliant PE image, so it may
> fail to boot with stricter implementations of UEFI PE loaders.
>
> Set minimal alignments and sizes specified by PE documentation [1]
> referenced by UEFI specification [2]. Align PE header to 8 bytes.

> Generate '.reloc' section with 2 entries and set reloc data directory.

Why?

>
> To make code more readable refactor tools/build.c:
> - Use mmap() to access kernel image.
> - Generate sections dynamically.
> - Setup sections protection. Since we cannot fit every
> needed section, set a part of protection flags
> dynamically during initialization. This step is omitted
> if CONFIG_EFI_DXE_MEM_ATTRIBUTES is not set.
>

If the commit log of a patch contains a bulleted list of the changes
that it implements, it is a very strong indicator that it needs to be
split up. Presenting this as a big ball of changes makes the life of a
reviewed unnecessarily hard.

> Reduce boot sector error message size since the space for the PE header
> before the zero page beginning is constrained.
>
> Explicitly change sections permissions in efi_pe_entry in case
> of incorrect EFI implementations and to reduce access rights to
> compressed kernel blob. By default it is set executable due to
> restriction in maximum number of sections that can fit before zero
> page.
>
> [1] https://download.microsoft.com/download/9/c/5/9c5b2167-8017-4bae-9fde-d599bac8184a/pecoff_v83.docx
> [2] https://uefi.org/sites/default/files/resources/UEFI_Spec_2_9_2021_03_18.pdf
>
> Signed-off-by: Evgeniy Baskov <baskov@xxxxxxxxx>
> ---
> arch/x86/boot/Makefile | 2 +-
> arch/x86/boot/header.S | 110 +----
> arch/x86/boot/tools/build.c | 575 +++++++++++++++---------
> drivers/firmware/efi/libstub/x86-stub.c | 63 ++-
> 4 files changed, 452 insertions(+), 298 deletions(-)
>
> diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
> index ffec8bb01ba8..828eb41c2603 100644
> --- a/arch/x86/boot/Makefile
> +++ b/arch/x86/boot/Makefile
> @@ -90,7 +90,7 @@ $(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\|startup_64\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|efi32_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|z_.*$$$/\#define ZO_\2 0x\1/p'
> +sed-zoffset := -e 's/^$[0-9a-fA-F]*$ [a-zA-Z] $startup_32\|startup_64\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|efi32_pe_entry\|input_data\|kernel_info\|_end\|_ehead\|_text\|_rodata\|z_.*$$$/\#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 f912d7770130..05a75f0a1876 100644
> --- a/arch/x86/boot/header.S
> +++ b/arch/x86/boot/header.S
> @@ -59,17 +59,16 @@ start2:
> cld
>
> movw $bugger_off_msg, %si
> + movw $bugger_off_msg_size, %cx
>
> msg_loop:
> lodsb
> - andb %al, %al
> - jz bs_die
> movb $0xe, %ah
> movw $7, %bx
> int $0x10
> - jmp msg_loop
> + decw %cx
> + jnz msg_loop
>
> -bs_die:
> # Allow the user to press a key, then reboot
> xorw %ax, %ax
> int $0x16
> @@ -89,12 +88,12 @@ bs_die:
>
> .section ".bsdata", "a"
> bugger_off_msg:
> - .ascii "Use a boot loader.\r\n"
> - .ascii "\n"
> - .ascii "Remove disk and press any key to reboot...\r\n"
> - .byte 0
> + .ascii "Use a boot loader. "
> + .ascii "Press a key to reboot"
> + .set bugger_off_msg_size, . - bugger_off_msg
>
> #ifdef CONFIG_EFI_STUB
> + .align 8
> pe_header:
> .long PE_MAGIC
>
> @@ -108,7 +107,7 @@ coff_header:
> .set pe_opt_magic, PE_OPT_MAGIC_PE32PLUS
> .word IMAGE_FILE_MACHINE_AMD64
> #endif
> - .word section_count # nr_sections
> + .word 0 # nr_sections
> .long 0 # TimeDateStamp
> .long 0 # PointerToSymbolTable
> .long 1 # NumberOfSymbols
> @@ -132,7 +131,7 @@ optional_header:
> # Filled in by build.c
> .long 0x0000 # AddressOfEntryPoint
>
> - .long 0x0200 # BaseOfCode
> + .long 0x1000 # BaseOfCode
> #ifdef CONFIG_X86_32
> .long 0 # data
> #endif
> @@ -145,8 +144,8 @@ extra_header_fields:
> #else
> .quad image_base # ImageBase
> #endif
> - .long 0x20 # SectionAlignment
> - .long 0x20 # FileAlignment
> + .long 0x1000 # SectionAlignment
> + .long 0x200 # FileAlignment
> .word 0 # MajorOperatingSystemVersion
> .word 0 # MinorOperatingSystemVersion
> .word LINUX_EFISTUB_MAJOR_VERSION # MajorImageVersion
> @@ -189,91 +188,14 @@ extra_header_fields:
> .quad 0 # CertificationTable
> .quad 0 # BaseRelocationTable
>
> - # Section table
> -section_table:
> - #
> - # The offset & size fields are filled in by build.c.
> - #
> - .ascii ".setup"
> - .byte 0
> - .byte 0
> - .long 0
> - .long 0x0 # startup_{32,64}
> - .long 0 # Size of initialized data
> - # on disk
> - .long 0x0 # startup_{32,64}
> - .long 0 # PointerToRelocations
> - .long 0 # PointerToLineNumbers
> - .word 0 # NumberOfRelocations
> - .word 0 # NumberOfLineNumbers
> - .long IMAGE_SCN_CNT_CODE | \
> - IMAGE_SCN_MEM_READ | \
> - IMAGE_SCN_MEM_EXECUTE | \
> - IMAGE_SCN_ALIGN_16BYTES # Characteristics
> -
> - #
> - # The EFI application loader requires a relocation section
> - # because EFI applications must be relocatable. The .reloc
> - # offset & size fields are filled in by build.c.
> #
> - .ascii ".reloc"
> - .byte 0
> - .byte 0
> - .long 0
> - .long 0
> - .long 0 # SizeOfRawData
> - .long 0 # PointerToRawData
> - .long 0 # PointerToRelocations
> - .long 0 # PointerToLineNumbers
> - .word 0 # NumberOfRelocations
> - .word 0 # NumberOfLineNumbers
> - .long IMAGE_SCN_CNT_INITIALIZED_DATA | \
> - IMAGE_SCN_MEM_READ | \
> - IMAGE_SCN_MEM_DISCARDABLE | \
> - IMAGE_SCN_ALIGN_1BYTES # Characteristics
> -
> -#ifdef CONFIG_EFI_MIXED
> - #
> - # The offset & size fields are filled in by build.c.
> + # Section table
> + # It is generated by build.c and here we just need
> + # to reserve some space for sections
> #
> - .asciz ".compat"
> - .long 0
> - .long 0x0
> - .long 0 # Size of initialized data
> - # on disk
> - .long 0x0
> - .long 0 # PointerToRelocations
> - .long 0 # PointerToLineNumbers
> - .word 0 # NumberOfRelocations
> - .word 0 # NumberOfLineNumbers
> - .long IMAGE_SCN_CNT_INITIALIZED_DATA | \
> - IMAGE_SCN_MEM_READ | \
> - IMAGE_SCN_MEM_DISCARDABLE | \
> - IMAGE_SCN_ALIGN_1BYTES # Characteristics
> -#endif
> +section_table:
> + .fill 40*5, 1, 0
>
> - #
> - # The offset & size fields are filled in by build.c.
> - #
> - .ascii ".text"
> - .byte 0
> - .byte 0
> - .byte 0
> - .long 0
> - .long 0x0 # startup_{32,64}
> - .long 0 # Size of initialized data
> - # on disk
> - .long 0x0 # startup_{32,64}
> - .long 0 # PointerToRelocations
> - .long 0 # PointerToLineNumbers
> - .word 0 # NumberOfRelocations
> - .word 0 # NumberOfLineNumbers
> - .long IMAGE_SCN_CNT_CODE | \
> - IMAGE_SCN_MEM_READ | \
> - IMAGE_SCN_MEM_EXECUTE | \
> - IMAGE_SCN_ALIGN_16BYTES # Characteristics
> -
> - .set section_count, (. - section_table) / 40
> #endif /* CONFIG_EFI_STUB */
>
> # Kernel attributes; used by setup. This is part 1 of the
> diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
> index a3725ad46c5a..dc3a1efb290e 100644
> --- a/arch/x86/boot/tools/build.c
> +++ b/arch/x86/boot/tools/build.c
> @@ -40,6 +40,8 @@ typedef unsigned char u8;
> typedef unsigned short u16;
> typedef unsigned int u32;
>
> +#define round_up(x, n) (((x) + (n) - 1) & ~((n) - 1))
> +
> #define DEFAULT_MAJOR_ROOT 0
> #define DEFAULT_MINOR_ROOT 0
> #define DEFAULT_ROOT_DEV (DEFAULT_MAJOR_ROOT << 8 | DEFAULT_MINOR_ROOT)
> @@ -59,12 +61,74 @@ u8 buf[SETUP_SECT_MAX*512];
> #define PECOFF_COMPAT_RESERVE 0x0
> #endif
>
> +#define PARAGRAPH_SIZE 16
> +#define SECTOR_SIZE 512
> +#define FILE_ALIGNMENT 512
> +#define SECTION_ALIGNMENT 4096
> +
> +#define RELOC_SECTION_SIZE 12
> +
> +#ifdef CONFIG_EFI_MIXED
> +#define COMPAT_SECTION_SIZE 8
> +#else
> +#define COMPAT_SECTION_SIZE 0
> +#endif
> +
> +#define DOS_PECOFF_HEADER_OFFSET 0x3c
> +
> +#define PECOFF_CODE_SIZE_OFFSET 0x1c
> +#define PECOFF_DATA_SIZE_OFFSET 0x20
> +#define PECOFF_IMAGE_SIZE_OFFSET 0x50
> +#define PECOFF_ENTRY_POINT_OFFSET 0x28
> +#define PECOFF_SECTIONS_COUNT_OFFSET 0x6
> +#define PECOFF_BASE_OF_CODE_OFFSET 0x2c
> +
> +#ifdef CONFIG_X86_32
> +#define PECOFF_SECTION_TABLE_OFFSET 0xa8
> +#define PECOFF_RELOC_DIR_OFFSET 0xa0
> +#else
> +#define PECOFF_SECTION_TABLE_OFFSET 0xb8
> +#define PECOFF_RELOC_DIR_OFFSET 0xb0
> +#endif
> +
> +#define PECOFF_SECTION_SIZE 0x28
> +
> +#define PECOFF_SCN_NAME_OFFSET 0x0
> +#define PECOFF_SCN_NAME_SIZE 8
> +#define PECOFF_SCN_MEMSZ_OFFSET 0x8
> +#define PECOFF_SCN_VADDR_OFFSET 0xc
> +#define PECOFF_SCN_FILESZ_OFFSET 0x10
> +#define PECOFF_SCN_OFFSET_OFFSET 0x14
> +#define PECOFF_SCN_FLAGS_OFFSET 0x24
> +
> +#define IMAGE_SCN_CNT_CODE 0x00000020 /* .text */
> +#define IMAGE_SCN_CNT_INITIALIZED_DATA 0x00000040 /* .data */
> +#define IMAGE_SCN_ALIGN_512BYTES 0x00a00000
> +#define IMAGE_SCN_ALIGN_4096BYTES 0x00d00000
> +#define IMAGE_SCN_MEM_DISCARDABLE 0x02000000 /* scn can be discarded */
> +#define IMAGE_SCN_MEM_EXECUTE 0x20000000 /* can be executed as code */
> +#define IMAGE_SCN_MEM_READ 0x40000000 /* readable */
> +#define IMAGE_SCN_MEM_WRITE 0x80000000 /* writeable */
> +

All of those defines need to go into a header file, probably include/linux/pe.h

> +#ifdef CONFIG_EFI_DXE_MEM_ATTRIBUTES
> +#define SCN_RW (IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE | IMAGE_SCN_ALIGN_4096BYTES)
> +#define SCN_RX (IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_EXECUTE | IMAGE_SCN_ALIGN_4096BYTES)
> +#define SCN_RO (IMAGE_SCN_MEM_READ | IMAGE_SCN_ALIGN_4096BYTES)
> +#else
> +/* With memory protection disabled all sections are RWX */
> +#define SCN_RW (IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE | \
> + IMAGE_SCN_MEM_EXECUTE | IMAGE_SCN_ALIGN_4096BYTES)
> +#define SCN_RX SCN_RW
> +#define SCN_RO SCN_RW
> +#endif
> +
> static unsigned long efi32_stub_entry;
> static unsigned long efi64_stub_entry;
> static unsigned long efi_pe_entry;
> static unsigned long efi32_pe_entry;
> static unsigned long kernel_info;
> static unsigned long startup_64;
> +static unsigned long _rodata;
> static unsigned long _ehead;
> static unsigned long _end;
>
> @@ -152,91 +216,126 @@ static void usage(void)
> die("Usage: build setup system zoffset.h image");
> }
>
> -#ifdef CONFIG_EFI_STUB
> -
> -static void update_pecoff_section_header_fields(char *section_name, u32 vma, u32 size, u32 datasz, u32 offset)
> +static void *map_file(const char *path, size_t *psize)
> {
> - unsigned int pe_header;
> - unsigned short num_sections;
> - u8 *section;
> -
> - pe_header = get_unaligned_le32(&buf[0x3c]);
> - num_sections = get_unaligned_le16(&buf[pe_header + 6]);
> -
> -#ifdef CONFIG_X86_32
> - section = &buf[pe_header + 0xa8];
> -#else
> - section = &buf[pe_header + 0xb8];
> -#endif
> -
> - while (num_sections > 0) {
> - if (strncmp((char*)section, section_name, 8) == 0) {
> - /* section header size field */
> - put_unaligned_le32(size, section + 0x8);
> + struct stat statbuf;
> + size_t size;
> + void *addr;
> + int fd;
>
> - /* section header vma field */
> - put_unaligned_le32(vma, section + 0xc);
> + fd = open(path, O_RDONLY);
> + if (fd < 0)
> + die("Unable to open `%s': %m", path);
> + if (fstat(fd, &statbuf))
> + die("Unable to stat `%s': %m", path);
>
> - /* section header 'size of initialised data' field */
> - put_unaligned_le32(datasz, section + 0x10);
> + size = statbuf.st_size;
> + /*
> + * Map one byte more, to allow adding null-terminator
> + * for text files.
> + */
> + addr = mmap(NULL, size + 1, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
> + if (addr == MAP_FAILED)
> + die("Unable to mmap '%s': %m", path);
>
> - /* section header 'file offset' field */
> - put_unaligned_le32(offset, section + 0x14);
> + close(fd);
>
> - break;
> - }
> - section += 0x28;
> - num_sections--;
> - }
> + *psize = size;
> + return addr;
> }
>
> -static void update_pecoff_section_header(char *section_name, u32 offset, u32 size)
> +static void unmap_file(void *addr, size_t size)
> {
> - update_pecoff_section_header_fields(section_name, offset, size, size, offset);
> + munmap(addr, size + 1);
> }
>
> -static void update_pecoff_setup_and_reloc(unsigned int size)
> +static void *map_output_file(const char *path, size_t size)
> {
> - u32 setup_offset = 0x200;
> - u32 reloc_offset = size - PECOFF_RELOC_RESERVE - PECOFF_COMPAT_RESERVE;
> -#ifdef CONFIG_EFI_MIXED
> - u32 compat_offset = reloc_offset + PECOFF_RELOC_RESERVE;
> -#endif
> - u32 setup_size = reloc_offset - setup_offset;
> + void *addr;
> + int fd;
>
> - update_pecoff_section_header(".setup", setup_offset, setup_size);
> - update_pecoff_section_header(".reloc", reloc_offset, PECOFF_RELOC_RESERVE);
> + fd = open(path, O_RDWR | O_CREAT, 0660);
> + if (fd < 0)
> + die("Unable to create `%s': %m", path);
>
> - /*
> - * Modify .reloc section contents with a single entry. The
> - * relocation is applied to offset 10 of the relocation section.
> - */
> - put_unaligned_le32(reloc_offset + 10, &buf[reloc_offset]);
> - put_unaligned_le32(10, &buf[reloc_offset + 4]);
> + if (ftruncate(fd, size))
> + die("Unable to resize `%s': %m", path);
>
> -#ifdef CONFIG_EFI_MIXED
> - update_pecoff_section_header(".compat", compat_offset, PECOFF_COMPAT_RESERVE);
> + addr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
> + if (addr == MAP_FAILED)
> + die("Unable to mmap '%s': %m", path);
>
> - /*
> - * Put the IA-32 machine type (0x14c) and the associated entry point
> - * address in the .compat section, so loaders can figure out which other
> - * execution modes this image supports.
> - */
> - buf[compat_offset] = 0x1;
> - buf[compat_offset + 1] = 0x8;
> - put_unaligned_le16(0x14c, &buf[compat_offset + 2]);
> - put_unaligned_le32(efi32_pe_entry + size, &buf[compat_offset + 4]);
> -#endif
> + return addr;
> }
>
> -static void update_pecoff_text(unsigned int text_start, unsigned int file_sz,
> - unsigned int init_sz)
> +#ifdef CONFIG_EFI_STUB
> +
> +static unsigned int reloc_offset;
> +static unsigned int compat_offset;
> +
> +#define MAX_SECTIONS 5
> +
> +static void emit_pecoff_section(const char *section_name, unsigned int size,
> + unsigned int bss, unsigned int *file_offset,
> + unsigned int *mem_offset, u32 flags)
> {
> + unsigned int section_memsz, section_filesz;
> unsigned int pe_header;
> - unsigned int text_sz = file_sz - text_start;
> - unsigned int bss_sz = init_sz - file_sz;
> + unsigned short num_sections;
> + u8 *pnum_sections;
> + u8 *section;
> +
> + pe_header = get_unaligned_le32(&buf[DOS_PECOFF_HEADER_OFFSET]);
> + pnum_sections = &buf[pe_header + PECOFF_SECTIONS_COUNT_OFFSET];
> + num_sections = get_unaligned_le16(pnum_sections);
> + if (num_sections >= MAX_SECTIONS)
> + die("Not enough space to generate all sections");
> +
> + section = &buf[pe_header + PECOFF_SECTION_TABLE_OFFSET];
> + section += PECOFF_SECTION_SIZE * num_sections;
> +
> + if ((size & (FILE_ALIGNMENT - 1)) || (bss & (FILE_ALIGNMENT - 1)))
> + die("Section '%s' is improperly aligned", section_name);
> +
> + section_memsz = round_up(size + bss, SECTION_ALIGNMENT);
> + section_filesz = round_up(size, FILE_ALIGNMENT);
> +
> + /* Zero out all section fields */
> + memset(section, 0, PECOFF_SECTION_SIZE);
> +
> + /* Section header size field */
> + strncpy((char *)(section + PECOFF_SCN_NAME_OFFSET),
> + section_name, PECOFF_SCN_NAME_SIZE);
>
> - pe_header = get_unaligned_le32(&buf[0x3c]);
> + put_unaligned_le32(section_memsz, section + PECOFF_SCN_MEMSZ_OFFSET);
> + put_unaligned_le32(*mem_offset, section + PECOFF_SCN_VADDR_OFFSET);
> + put_unaligned_le32(section_filesz, section + PECOFF_SCN_FILESZ_OFFSET);
> + put_unaligned_le32(*file_offset, section + PECOFF_SCN_OFFSET_OFFSET);
> + put_unaligned_le32(flags, section + PECOFF_SCN_FLAGS_OFFSET);
> +
> + put_unaligned_le16(num_sections + 1, pnum_sections);
> +
> + *mem_offset += section_memsz;
> + *file_offset += section_filesz;
> +
> +}
> +
> +#define BASE_RVA 0x1000
> +
> +static unsigned int update_pecoff_sections(unsigned int setup_size,
> + unsigned int file_size,
> + unsigned int init_size,
> + unsigned int text_size)
> +{
> + /* First section starts at 512 byes, after PE header */
> + unsigned int mem_offset = BASE_RVA, file_offset = SECTOR_SIZE;
> + unsigned int compat_size, reloc_size, image_size, text_rva;
> + unsigned int pe_header, bss_size, text_rva_diff, reloc_rva;
> +
> + pe_header = get_unaligned_le32(&buf[DOS_PECOFF_HEADER_OFFSET]);
> +
> + if (get_unaligned_le32(&buf[pe_header + PECOFF_SECTIONS_COUNT_OFFSET]))
> + die("Some sections present in PE file");
>
> /*
> * The PE/COFF loader may load the image at an address which is
> @@ -247,42 +346,121 @@ static void update_pecoff_text(unsigned int text_start, unsigned int file_sz,
> * add slack to allow the buffer to be aligned within the declared size
> * of the image.
> */
> - bss_sz += CONFIG_PHYSICAL_ALIGN;
> - init_sz += CONFIG_PHYSICAL_ALIGN;
> + init_size += CONFIG_PHYSICAL_ALIGN;
> + image_size = init_size;
> +
> + reloc_size = round_up(RELOC_SECTION_SIZE, FILE_ALIGNMENT);
> + compat_size = round_up(COMPAT_SECTION_SIZE, FILE_ALIGNMENT);
> +
> + /*
> + * Let's remove extra memory used by special sections
> + * and use it as a part of bss.
> + */
> + init_size -= round_up(reloc_size, SECTION_ALIGNMENT);
> + init_size -= round_up(compat_size, SECTION_ALIGNMENT);
> + if (init_size < file_size + setup_size) {
> + init_size = file_size + setup_size;
> + image_size += round_up(reloc_size, SECTION_ALIGNMENT);
> + image_size += round_up(compat_size, SECTION_ALIGNMENT);
> + }
>
> /*
> - * Size of code: Subtract the size of the first sector (512 bytes)
> - * which includes the header.
> + * Update sections offsets.
> + * NOTE: Order is important
> */
> - put_unaligned_le32(file_sz - 512 + bss_sz, &buf[pe_header + 0x1c]);
>
> - /* Size of image */
> - put_unaligned_le32(init_sz, &buf[pe_header + 0x50]);
> + bss_size = init_size - file_size - setup_size;
> +
> + emit_pecoff_section(".setup", setup_size - SECTOR_SIZE, 0,
> + &file_offset, &mem_offset, SCN_RO |
> + IMAGE_SCN_CNT_INITIALIZED_DATA);
> +
> + text_rva_diff = mem_offset - file_offset;
> + text_rva = mem_offset;
> + emit_pecoff_section(".text", text_size, 0,
> + &file_offset, &mem_offset, SCN_RX |
> + IMAGE_SCN_CNT_CODE);
> +
> + /* Check that kernel sections mapping is contiguous */
> + if (text_rva_diff != mem_offset - file_offset)
> + die("Kernel sections mapping is wrong: %#x != %#x",
> + mem_offset - file_offset, text_rva_diff);
> +
> + emit_pecoff_section(".data", file_size - text_size, bss_size,
> + &file_offset, &mem_offset, SCN_RW |
> + IMAGE_SCN_CNT_INITIALIZED_DATA);
> +
> + reloc_offset = file_offset;
> + reloc_rva = mem_offset;
> + emit_pecoff_section(".reloc", reloc_size, 0,
> + &file_offset, &mem_offset, SCN_RW |
> + IMAGE_SCN_CNT_INITIALIZED_DATA |
> + IMAGE_SCN_MEM_DISCARDABLE);
> +
> + compat_offset = file_offset;
> +#ifdef CONFIG_EFI_MIXED
> + emit_pecoff_section(".comat", compat_size, 0,
> + &file_offset, &mem_offset, SCN_RW |
> + IMAGE_SCN_CNT_INITIALIZED_DATA |
> + IMAGE_SCN_MEM_DISCARDABLE);
> +#endif
> +
> + if (file_size + setup_size + reloc_size + compat_size != file_offset)
> + die("file_size(%#x) != filesz(%#x)",
> + file_size + setup_size + reloc_size + compat_size, file_offset);
> +
> + /* Size of code. */
> + put_unaligned_le32(round_up(text_size, SECTION_ALIGNMENT),
> + &buf[pe_header + PECOFF_CODE_SIZE_OFFSET]);
> + /*
> + * Size of data.
> + * Exclude text size and first sector, which contains PE header.
> + */
> + put_unaligned_le32(mem_offset - round_up(text_size, SECTION_ALIGNMENT),
> + &buf[pe_header + PECOFF_DATA_SIZE_OFFSET]);
> +
> + /* Size of image. */
> + put_unaligned_le32(mem_offset, &buf[pe_header + PECOFF_IMAGE_SIZE_OFFSET]);
>
> /*
> * Address of entry point for PE/COFF executable
> */
> - put_unaligned_le32(text_start + efi_pe_entry, &buf[pe_header + 0x28]);
> + put_unaligned_le32(text_rva + efi_pe_entry, &buf[pe_header + PECOFF_ENTRY_POINT_OFFSET]);
>
> - update_pecoff_section_header_fields(".text", text_start, text_sz + bss_sz,
> - text_sz, text_start);
> -}
> + /*
> + * BaseOfCode for PE/COFF executable
> + */
> + put_unaligned_le32(text_rva, &buf[pe_header + PECOFF_BASE_OF_CODE_OFFSET]);
>
> -static int reserve_pecoff_reloc_section(int c)
> -{
> - /* Reserve 0x20 bytes for .reloc section */
> - memset(buf+c, 0, PECOFF_RELOC_RESERVE);
> - return PECOFF_RELOC_RESERVE;
> + /*
> + * Since we have generated .reloc section, we need to
> + * fill-in Reloc directory
> + */
> + put_unaligned_le32(reloc_rva, &buf[pe_header + PECOFF_RELOC_DIR_OFFSET]);
> + put_unaligned_le32(RELOC_SECTION_SIZE, &buf[pe_header + PECOFF_RELOC_DIR_OFFSET + 4]);
> +
> + return file_offset;
> }
>
> -static void efi_stub_defaults(void)
> +static void generate_pecoff_section_data(u8 *output, unsigned int setup_size)
> {
> - /* Defaults for old kernel */
> -#ifdef CONFIG_X86_32
> - efi_pe_entry = 0x10;
> -#else
> - efi_pe_entry = 0x210;
> - startup_64 = 0x200;
> + /*
> + * Modify .reloc section contents with a two entries. The
> + * relocation is applied to offset 10 of the relocation section.
> + */
> + put_unaligned_le32(reloc_offset + RELOC_SECTION_SIZE, &output[reloc_offset]);
> + put_unaligned_le32(RELOC_SECTION_SIZE, &output[reloc_offset + 4]);
> +
> +#ifdef CONFIG_EFI_MIXED
> + /*
> + * Put the IA-32 machine type (0x14c) and the associated entry point
> + * address in the .compat section, so loaders can figure out which other
> + * execution modes this image supports.
> + */
> + output[compat_offset] = 0x1;
> + output[compat_offset + 1] = 0x8;
> + put_unaligned_le16(0x14c, &output[compat_offset + 2]);
> + put_unaligned_le32(efi32_pe_entry + setup_size, &output[compat_offset + 4]);
> #endif
> }
>
> @@ -297,33 +475,27 @@ static void efi_stub_entry_update(void)
>
> #ifdef CONFIG_EFI_MIXED
> if (efi32_stub_entry != addr)
> - die("32-bit and 64-bit EFI entry points do not match\n");
> + die("32-bit and 64-bit EFI entry points do not match");
> #endif
> put_unaligned_le32(addr, &buf[0x264]);
> }
>
> +static void efi_stub_update_defaults(void)
> +{
> + /* Defaults for old kernel */
> +#ifdef CONFIG_X86_32
> + efi_pe_entry = 0x10;
> +#else
> + efi_pe_entry = 0x210;
> + startup_64 = 0x200;
> +#endif
> +}
> #else
>
> -static inline void update_pecoff_setup_and_reloc(unsigned int size) {}
> -static inline void update_pecoff_text(unsigned int text_start,
> - unsigned int file_sz,
> - unsigned int init_sz) {}
> -static inline void efi_stub_defaults(void) {}
> -static inline void efi_stub_entry_update(void) {}
> +static void efi_stub_update_defaults(void) {}
>
> -static inline int reserve_pecoff_reloc_section(int c)
> -{
> - return 0;
> -}
> #endif /* CONFIG_EFI_STUB */
>
> -static int reserve_pecoff_compat_section(int c)
> -{
> - /* Reserve 0x20 bytes for .compat section */
> - memset(buf+c, 0, PECOFF_COMPAT_RESERVE);
> - return PECOFF_COMPAT_RESERVE;
> -}
> -
> /*
> * Parse zoffset.h and find the entry points. We could just #include zoffset.h
> * but that would mean tools/build would have to be rebuilt every time. It's
> @@ -336,20 +508,15 @@ static int reserve_pecoff_compat_section(int c)
>
> static void parse_zoffset(char *fname)
> {
> - FILE *file;
> - char *p;
> - int c;
> + size_t size;
> + char *data, *p;
>
> - file = fopen(fname, "r");
> - if (!file)
> - die("Unable to open `%s': %m", fname);
> - c = fread(buf, 1, sizeof(buf) - 1, file);
> - if (ferror(file))
> - die("read-error on `zoffset.h'");
> - fclose(file);
> - buf[c] = 0;
> + data = map_file(fname, &size);
> +
> + /* We can do that, since we mapped one byte more */
> + data[size] = 0;
>
> - p = (char *)buf;
> + p = (char *)data;
>
> while (p && *p) {
> PARSE_ZOFS(p, efi32_stub_entry);
> @@ -358,6 +525,7 @@ static void parse_zoffset(char *fname)
> PARSE_ZOFS(p, efi32_pe_entry);
> PARSE_ZOFS(p, kernel_info);
> PARSE_ZOFS(p, startup_64);
> + PARSE_ZOFS(p, _rodata);
> PARSE_ZOFS(p, _ehead);
> PARSE_ZOFS(p, _end);
>
> @@ -365,82 +533,93 @@ static void parse_zoffset(char *fname)
> while (p && (*p == '\r' || *p == '\n'))
> p++;
> }
> +
> + unmap_file(data, size);
> }
>
> -int main(int argc, char ** argv)
> +static unsigned int read_setup(char *path)
> {
> - unsigned int i, sz, setup_sectors, init_sz;
> - int c;
> - u32 sys_size;
> - struct stat sb;
> - FILE *file, *dest;
> - int fd;
> - void *kernel;
> - u32 crc = 0xffffffffUL;
> -
> - efi_stub_defaults();
> -
> - if (argc != 5)
> - usage();
> - parse_zoffset(argv[3]);
> -
> - dest = fopen(argv[4], "w");
> - if (!dest)
> - die("Unable to write `%s': %m", argv[4]);
> + FILE *file;
> + unsigned int setup_size, file_size;
>
> /* Copy the setup code */
> - file = fopen(argv[1], "r");
> + file = fopen(path, "r");
> if (!file)
> - die("Unable to open `%s': %m", argv[1]);
> - c = fread(buf, 1, sizeof(buf), file);
> + die("Unable to open `%s': %m", path);
> +
> + file_size = fread(buf, 1, sizeof(buf), file);
> if (ferror(file))
> die("read-error on `setup'");
> - if (c < 1024)
> +
> + if (file_size < 2 * SECTOR_SIZE)
> die("The setup must be at least 1024 bytes");
> - if (get_unaligned_le16(&buf[510]) != 0xAA55)
> +
> + if (get_unaligned_le16(&buf[SECTOR_SIZE - 2]) != 0xAA55)
> die("Boot block hasn't got boot flag (0xAA55)");
> - fclose(file);
>
> - c += reserve_pecoff_compat_section(c);
> - c += reserve_pecoff_reloc_section(c);
> + fclose(file);
>
> /* Pad unused space with zeros */
> - setup_sectors = (c + 511) / 512;
> - if (setup_sectors < SETUP_SECT_MIN)
> - setup_sectors = SETUP_SECT_MIN;
> - i = setup_sectors*512;
> - memset(buf+c, 0, i-c);
> + setup_size = round_up(file_size, SECTOR_SIZE);
> +
> + if (setup_size < SETUP_SECT_MIN * SECTOR_SIZE)
> + setup_size = SETUP_SECT_MIN * SECTOR_SIZE;
>
> - update_pecoff_setup_and_reloc(i);
> + /*
> + * Global buffer is already initialised
> + * to 0, but just in case, zero out padding.
> + */
> +
> + memset(buf + file_size, 0, setup_size - file_size);
> +
> + return setup_size;
> +}
> +
> +int main(int argc, char **argv)
> +{
> + size_t kern_file_size;
> + unsigned int setup_size;
> + unsigned int setup_sectors;
> + unsigned int init_size;
> + unsigned int total_size;
> + unsigned int kern_size;
> + void *kernel;
> + u32 crc = 0xffffffffUL;
> + u8 *output;
> +
> + if (argc != 5)
> + usage();
> +
> + efi_stub_update_defaults();
> + parse_zoffset(argv[3]);
> +
> + setup_size = read_setup(argv[1]);
> +
> + setup_sectors = setup_size/SECTOR_SIZE;
>
> /* Set the default root device */
> put_unaligned_le16(DEFAULT_ROOT_DEV, &buf[508]);
>
> - /* Open and stat the kernel file */
> - fd = open(argv[2], O_RDONLY);
> - if (fd < 0)
> - die("Unable to open `%s': %m", argv[2]);
> - if (fstat(fd, &sb))
> - die("Unable to stat `%s': %m", argv[2]);
> - sz = sb.st_size;
> - kernel = mmap(NULL, sz, PROT_READ, MAP_SHARED, fd, 0);
> - if (kernel == MAP_FAILED)
> - die("Unable to mmap '%s': %m", argv[2]);
> - /* Number of 16-byte paragraphs, including space for a 4-byte CRC */
> - sys_size = (sz + 15 + 4) / 16;
> + /* Map kernel file to memory */
> + kernel = map_file(argv[2], &kern_file_size);
> +
> #ifdef CONFIG_EFI_STUB
> - /*
> - * COFF requires minimum 32-byte alignment of sections, and
> - * adding a signature is problematic without that alignment.
> - */
> - sys_size = (sys_size + 1) & ~1;
> + /* PE specification require 512-byte minimum section file alignment */
> + kern_size = round_up(kern_file_size + 4, SECTOR_SIZE);
> +#else
> + /* Number of 16-byte paragraphs, including space for a 4-byte CRC */
> + kern_size = round_up(kern_file_size + 4, PARAGRAPH_SIZE);
> #endif
>
> /* Patch the setup code with the appropriate size parameters */
> - buf[0x1f1] = setup_sectors-1;
> - put_unaligned_le32(sys_size, &buf[0x1f4]);
> + buf[0x1f1] = setup_sectors - 1;
> + put_unaligned_le32(kern_size/PARAGRAPH_SIZE, &buf[0x1f4]);
> +
> + /* Update kernel_info offset. */
> + put_unaligned_le32(kernel_info, &buf[0x268]);
> +
> + init_size = get_unaligned_le32(&buf[0x260]);
>
> - init_sz = get_unaligned_le32(&buf[0x260]);
> #ifdef CONFIG_EFI_STUB
> /*
> * The decompression buffer will start at ImageBase. When relocating
> @@ -456,45 +635,39 @@ int main(int argc, char ** argv)
> * For future-proofing, increase init_sz if necessary.
> */
>
> - if (init_sz - _end < i + _ehead) {
> - init_sz = (i + _ehead + _end + 4095) & ~4095;
> - put_unaligned_le32(init_sz, &buf[0x260]);
> + if (init_size - _end < setup_size + _ehead) {
> + init_size = round_up(setup_size + _ehead + _end, SECTION_ALIGNMENT);
> + put_unaligned_le32(init_size, &buf[0x260]);
> }
> -#endif
> - update_pecoff_text(setup_sectors * 512, i + (sys_size * 16), init_sz);
>
> - efi_stub_entry_update();
> + total_size = update_pecoff_sections(setup_size, kern_size, init_size, _rodata);
>
> - /* Update kernel_info offset. */
> - put_unaligned_le32(kernel_info, &buf[0x268]);
> + efi_stub_entry_update();
> +#else
> + (void)init_size;
> + total_size = setup_size + kern_size;
> +#endif
>
> - crc = partial_crc32(buf, i, crc);
> - if (fwrite(buf, 1, i, dest) != i)
> - die("Writing setup failed");
> + output = map_output_file(argv[4], total_size);
>
> - /* Copy the kernel code */
> - crc = partial_crc32(kernel, sz, crc);
> - if (fwrite(kernel, 1, sz, dest) != sz)
> - die("Writing kernel failed");
> + memcpy(output, buf, setup_size);
> + memcpy(output + setup_size, kernel, kern_file_size);
> + memset(output + setup_size + kern_file_size, 0, kern_size - kern_file_size);
>
> - /* Add padding leaving 4 bytes for the checksum */
> - while (sz++ < (sys_size*16) - 4) {
> - crc = partial_crc32_one('\0', crc);
> - if (fwrite("\0", 1, 1, dest) != 1)
> - die("Writing padding failed");
> - }
> +#ifdef CONFIG_EFI_STUB
> + generate_pecoff_section_data(output, setup_size);
> +#endif
>
> - /* Write the CRC */
> - put_unaligned_le32(crc, buf);
> - if (fwrite(buf, 1, 4, dest) != 4)
> - die("Writing CRC failed");
> + /* Calculate and write kernel checksum. */
> + crc = partial_crc32(output, total_size - 4, crc);
> + put_unaligned_le32(crc, &output[total_size - 4]);
>
> - /* Catch any delayed write failures */
> - if (fclose(dest))
> - die("Writing image failed");
> + /* Catch any delayed write failures. */
> + if (munmap(output, total_size) < 0)
> + die("Writing kernel failed");
>
> - close(fd);
> + unmap_file(kernel, kern_file_size);
>
> - /* Everything is OK */
> + /* Everything is OK. */
> return 0;
> }
> diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
> index 680184034cb7..914106d547a6 100644
> --- a/drivers/firmware/efi/libstub/x86-stub.c
> +++ b/drivers/firmware/efi/libstub/x86-stub.c
> @@ -392,6 +392,60 @@ static void __noreturn efi_exit(efi_handle_t handle, efi_status_t status)
> asm("hlt");
> }
>
> +
> +/*
> + * Manually setup memory protection attributes for each ELF section
> + * since we cannot do it properly by using PE sections.
> + */
> +static void setup_sections_memory_protection(void *image_base,
> + unsigned long init_size)
> +{
> +#ifdef CONFIG_EFI_DXE_MEM_ATTRIBUTES
> + efi_dxe_table = get_efi_config_table(EFI_DXE_SERVICES_TABLE_GUID);
> +
> + if (!efi_dxe_table ||
> + efi_dxe_table->hdr.signature != EFI_DXE_SERVICES_TABLE_SIGNATURE) {
> + efi_warn("Unable to locate EFI DXE services table\n");
> + efi_dxe_table = NULL;
> + return;
> + }
> +
> + extern char _head[], _ehead[];
> + extern char _compressed[], _ecompressed[];
> + extern char _text[], _etext[];
> + extern char _rodata[], _erodata[];
> + extern char _data[];
> +
> + /* .setup [image_base, _head] */
> + efi_adjust_memory_range_protection((unsigned long)image_base,
> + (unsigned long)_head - (unsigned long)image_base,
> + EFI_MEMORY_RO | EFI_MEMORY_XP);
> + /* .head.text [_head, _ehead] */
> + efi_adjust_memory_range_protection((unsigned long)_head,
> + (unsigned long)_ehead - (unsigned long)_head,
> + EFI_MEMORY_RO);
> + /* .rodata..compressed [_compressed, _ecompressed] */
> + efi_adjust_memory_range_protection((unsigned long)_compressed,
> + (unsigned long)_ecompressed - (unsigned long)_compressed,
> + EFI_MEMORY_RO | EFI_MEMORY_XP);
> + /* .text [_text, _etext] */
> + efi_adjust_memory_range_protection((unsigned long)_text,
> + (unsigned long)_etext - (unsigned long)_text,
> + EFI_MEMORY_RO);
> + /* .rodata [_rodata, _erodata] */
> + efi_adjust_memory_range_protection((unsigned long)_rodata,
> + (unsigned long)_erodata - (unsigned long)_rodata,
> + EFI_MEMORY_RO | EFI_MEMORY_XP);
> + /* .data, .bss [_data, image_base + init_size] */
> + efi_adjust_memory_range_protection((unsigned long)_data,
> + (unsigned long)image_base + init_size - (unsigned long)_rodata,
> + EFI_MEMORY_XP);
> +#else
> + (void)image_base;
> + (void)init_size;
> +#endif
> +}
> +
> void __noreturn efi_stub_entry(efi_handle_t handle,
> efi_system_table_t *sys_table_arg,
> struct boot_params *boot_params);
> @@ -438,10 +492,15 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
>
> hdr = &boot_params->hdr;
>
> - /* Copy the setup header from the second sector to boot_params */
> - memcpy(&hdr->jump, image_base + 512,
> + /*
> + * Copy the setup header from the second sector
> + * (mapped to image_base + 0x1000) to boot_params
> + */
> + memcpy(&hdr->jump, image_base + 0x1000,
> sizeof(struct setup_header) - offsetof(struct setup_header, jump));
>
> + setup_sections_memory_protection(image_base, hdr->init_size);
> +
> /*
> * Fill out some of the header fields ourselves because the
> * EFI firmware loader doesn't load the first sector.
> --
> 2.35.1
>

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