Commit b2fe1780 authored by Matthew Garrett's avatar Matthew Garrett

Initial commit

parents
ARCH = $(shell uname -m | sed s,i[3456789]86,ia32,)
LIB_PATH = /usr/lib64
EFI_INCLUDE = /usr/include/efi
EFI_INCLUDES = -I$(EFI_INCLUDE) -I$(EFI_INCLUDE)/$(ARCH) -I$(EFI_INCLUDE)/protocol
EFI_PATH = /usr/lib64/gnuefi
LIB_GCC = $(shell $(CC) -print-libgcc-file-name)
EFI_LIBS = -lefi -lgnuefi $(LIB_GCC)
EFI_CRT_OBJS = $(EFI_PATH)/crt0-efi-$(ARCH).o
EFI_LDS = $(EFI_PATH)/elf_$(ARCH)_efi.lds
CFLAGS = -O2 -fno-stack-protector -fno-strict-aliasing -fpic -fshort-wchar \
-Wall \
$(EFI_INCLUDES)
ifeq ($(ARCH),x86_64)
CFLAGS += -DEFI_FUNCTION_WRAPPER
endif
LDFLAGS = -nostdlib -znocombreloc -T $(EFI_LDS) -shared -Bsymbolic -L$(EFI_PATH) -L$(LIB_PATH) $(EFI_CRT_OBJS)
TARGET = shim.efi
OBJS = shim.o
all: $(TARGET)
shim.efi: $(OBJS)
%.efi: %.o
$(LD) $(LDFLAGS) $^ -o $@ $(EFI_LIBS)
objcopy -j .text -j .sdata -j .data \
-j .dynamic -j .dynsym -j .rel \
-j .rela -j .reloc \
--target=efi-app-$(ARCH) $@
strip $@
clean:
rm -f $(TARGET) $(OBJS)
This diff is collapsed.
/* Read path */
/* Load real bootloader */
/* Check signature */
/* Relocate real bootloader */
/* Jump to real bootloader */
#include <efi.h>
#include <efilib.h>
#include "PeImage.h"
EFI_SYSTEM_TABLE *systab;
EFI_STATUS (EFIAPI *entry_point) (EFI_HANDLE image_handle, EFI_SYSTEM_TABLE *system_table);
EFI_STATUS load_grub (EFI_HANDLE image_handle, void **grubdata, int *grubsize)
{
EFI_GUID loaded_image_protocol = LOADED_IMAGE_PROTOCOL;
EFI_GUID simple_file_system_protocol = SIMPLE_FILE_SYSTEM_PROTOCOL;
EFI_GUID file_info_id = EFI_FILE_INFO_ID;
EFI_STATUS efi_status;
EFI_LOADED_IMAGE *li;
EFI_FILE_IO_INTERFACE *drive;
EFI_FILE_INFO *fileinfo = NULL;
EFI_FILE *root, *grub;
FILEPATH_DEVICE_PATH *FilePath;
CHAR16 *PathName;
EFI_HANDLE device;
unsigned int buffersize = 0;
efi_status = uefi_call_wrapper(BS->HandleProtocol, 3, image_handle,
&loaded_image_protocol, &li);
if (efi_status != EFI_SUCCESS)
return efi_status;
if (DevicePathType(li->FilePath) != MEDIA_DEVICE_PATH ||
DevicePathSubType(li->FilePath) != MEDIA_FILEPATH_DP)
return EFI_NOT_FOUND;
FilePath = (FILEPATH_DEVICE_PATH *)li->FilePath;
PathName = AllocatePool(StrLen(FilePath->PathName) + StrLen(L"grub.efi"));
if (!PathName)
return EFI_LOAD_ERROR;
StrCpy(PathName, FilePath->PathName);
StrCat(PathName, L"grub.efi");
device = li->DeviceHandle;
efi_status = uefi_call_wrapper(BS->HandleProtocol, 3, device,
&simple_file_system_protocol, &drive);
if (efi_status != EFI_SUCCESS) {
Print(L"Failed to find fs\n");
return efi_status;
}
efi_status = uefi_call_wrapper(drive->OpenVolume, 2, drive, &root);
if (efi_status != EFI_SUCCESS) {
Print(L"Failed to open fs\n");
return efi_status;
}
efi_status = uefi_call_wrapper(root->Open, 5, root, &grub, PathName,
EFI_FILE_MODE_READ, 0);
if (efi_status != EFI_SUCCESS) {
Print(L"Failed to open grub\n");
return efi_status;
}
efi_status = uefi_call_wrapper(grub->GetInfo, 4, grub, &file_info_id,
&buffersize, fileinfo);
if (efi_status == EFI_BUFFER_TOO_SMALL) {
fileinfo = AllocatePool(buffersize);
efi_status = uefi_call_wrapper(grub->GetInfo, 4, grub,
&file_info_id, &buffersize,
fileinfo);
}
if (efi_status != EFI_SUCCESS) {
Print(L"Unable to get file info\n");
return efi_status;
}
buffersize = fileinfo->FileSize;
*grubdata = AllocatePool(buffersize);
efi_status = uefi_call_wrapper(grub->Read, 3, grub, &buffersize,
*grubdata);
if (efi_status != EFI_SUCCESS) {
Print(L"Unexpected return from initial read\n");
return efi_status;
}
if (efi_status != EFI_SUCCESS) {
Print(L"Unable to read grub\n");
return efi_status;
}
*grubsize = buffersize;
return EFI_SUCCESS;
}
EFI_STATUS read_header(void *grubdata, PE_COFF_LOADER_IMAGE_CONTEXT *context)
{
EFI_IMAGE_DOS_HEADER *DosHdr = grubdata;
EFI_IMAGE_OPTIONAL_HEADER_UNION *PEHdr = grubdata;
if (DosHdr->e_magic == EFI_IMAGE_DOS_SIGNATURE)
PEHdr = (EFI_IMAGE_OPTIONAL_HEADER_UNION *)((char *)grubdata + DosHdr->e_lfanew);
if (PEHdr->Te.Signature != EFI_IMAGE_NT_SIGNATURE) {
Print(L"Unsupported image type\n");
return EFI_UNSUPPORTED;
}
if (PEHdr->Pe32.FileHeader.Characteristics & EFI_IMAGE_FILE_RELOCS_STRIPPED) {
Print(L"Unsupported image - Relocations have been stripped\n");
return EFI_UNSUPPORTED;
}
if (PEHdr->Pe32.OptionalHeader.Magic != EFI_IMAGE_NT_OPTIONAL_HDR64_MAGIC) {
Print(L"Only 64-bit images supported\n");
return EFI_UNSUPPORTED;
}
context->ImageAddress = PEHdr->Pe32Plus.OptionalHeader.ImageBase;
PEHdr->Pe32Plus.OptionalHeader.ImageBase = (UINT64)grubdata;
context->ImageSize = (UINT64)PEHdr->Pe32Plus.OptionalHeader.SizeOfImage;
context->SizeOfHeaders = PEHdr->Pe32Plus.OptionalHeader.SizeOfHeaders;
context->EntryPoint = PEHdr->Pe32Plus.OptionalHeader.AddressOfEntryPoint;
context->RelocDir = &PEHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_BASERELOC];
context->NumberOfRvaAndSizes = PEHdr->Pe32Plus.OptionalHeader.NumberOfRvaAndSizes;
context->NumberOfSections = PEHdr->Pe32.FileHeader.NumberOfSections;
context->FirstSection = (EFI_IMAGE_SECTION_HEADER *)((char *)PEHdr + PEHdr->Pe32.FileHeader.SizeOfOptionalHeader + sizeof(UINT32) + sizeof(EFI_IMAGE_FILE_HEADER));
return EFI_SUCCESS;
}
void *ImageAddress (void *image, int size, unsigned int address)
{
if (address > size)
return 0;
return image + address;
}
EFI_STATUS relocate_grub (PE_COFF_LOADER_IMAGE_CONTEXT *context, void *grubdata)
{
EFI_IMAGE_BASE_RELOCATION *RelocBase, *RelocBaseEnd;
UINT64 Adjust;
UINT16 *Reloc, *RelocEnd;
char *Fixup, *FixupBase, *FixupData = NULL;
UINT16 *Fixup16;
UINT32 *Fixup32;
UINT64 *Fixup64;
int size = context->ImageSize;
void *ImageEnd = (char *)grubdata + size;
if (context->NumberOfRvaAndSizes <= EFI_IMAGE_DIRECTORY_ENTRY_BASERELOC) {
Print(L"Image has no relocation entry\n");
return EFI_UNSUPPORTED;
}
RelocBase = ImageAddress(grubdata, size, context->RelocDir->VirtualAddress);
RelocBaseEnd = ImageAddress(grubdata, size, context->RelocDir->VirtualAddress + context->RelocDir->Size - 1);
if (!RelocBase || !RelocBaseEnd) {
Print(L"Reloc table overflows binary\n");
return EFI_UNSUPPORTED;
}
Adjust = (UINT64)grubdata - context->ImageAddress;
while (RelocBase < RelocBaseEnd) {
Reloc = (UINT16 *) ((char *) RelocBase + sizeof (EFI_IMAGE_BASE_RELOCATION));
RelocEnd = (UINT16 *) ((char *) RelocBase + RelocBase->SizeOfBlock);
if ((void *)RelocEnd < grubdata || (void *)RelocEnd > ImageEnd) {
Print(L"Reloc entry overflows binary\n");
return EFI_UNSUPPORTED;
}
FixupBase = ImageAddress(grubdata, size, RelocBase->VirtualAddress);
if (!FixupBase) {
Print(L"Invalid fixupbase\n");
return EFI_UNSUPPORTED;
}
while (Reloc < RelocEnd) {
Fixup = FixupBase + (*Reloc & 0xFFF);
switch ((*Reloc) >> 12) {
case EFI_IMAGE_REL_BASED_ABSOLUTE:
break;
case EFI_IMAGE_REL_BASED_HIGH:
Fixup16 = (UINT16 *) Fixup;
*Fixup16 = (UINT16) (*Fixup16 + ((UINT16) ((UINT32) Adjust >> 16)));
if (FixupData != NULL) {
*(UINT16 *) FixupData = *Fixup16;
FixupData = FixupData + sizeof (UINT16);
}
break;
case EFI_IMAGE_REL_BASED_LOW:
Fixup16 = (UINT16 *) Fixup;
*Fixup16 = (UINT16) (*Fixup16 + (UINT16) Adjust);
if (FixupData != NULL) {
*(UINT16 *) FixupData = *Fixup16;
FixupData = FixupData + sizeof (UINT16);
}
break;
case EFI_IMAGE_REL_BASED_HIGHLOW:
Fixup32 = (UINT32 *) Fixup;
*Fixup32 = *Fixup32 + (UINT32) Adjust;
if (FixupData != NULL) {
FixupData = ALIGN_POINTER (FixupData, sizeof (UINT32));
*(UINT32 *)FixupData = *Fixup32;
FixupData = FixupData + sizeof (UINT32);
}
break;
case EFI_IMAGE_REL_BASED_DIR64:
Fixup64 = (UINT64 *) Fixup;
*Fixup64 = *Fixup64 + (UINT64) Adjust;
if (FixupData != NULL) {
FixupData = ALIGN_POINTER (FixupData, sizeof(UINT64));
*(UINT64 *)(FixupData) = *Fixup64;
FixupData = FixupData + sizeof(UINT64);
}
break;
default:
Print(L"Unknown relocation\n");
return EFI_UNSUPPORTED;
}
Reloc += 1;
}
RelocBase = (EFI_IMAGE_BASE_RELOCATION *) RelocEnd;
}
return EFI_SUCCESS;
}
EFI_STATUS handle_grub (void *grubdata, int grubsize)
{
EFI_STATUS efi_status;
char *buffer;
int i, size;
EFI_IMAGE_SECTION_HEADER *Section;
char *base, *end, *maxend = 0;
PE_COFF_LOADER_IMAGE_CONTEXT context;
efi_status = read_header(grubdata, &context);
if (efi_status != EFI_SUCCESS) {
Print(L"Failed to read header\n");
return efi_status;
}
buffer = AllocatePool(context.ImageSize);
CopyMem(buffer, grubdata, context.SizeOfHeaders);
Section = context.FirstSection;
for (i = 0; i < context.NumberOfSections; i++) {
size = Section->Misc.VirtualSize;
if (size > Section->SizeOfRawData)
size = Section->SizeOfRawData;
base = ImageAddress (buffer, context.ImageSize, Section->VirtualAddress);
end = ImageAddress (buffer, context.ImageSize, Section->VirtualAddress + size - 1);
if (!base || !end) {
Print(L"Invalid section size\n");
return EFI_UNSUPPORTED;
}
if (end > maxend)
maxend = end;
if (Section->SizeOfRawData > 0)
CopyMem(base, grubdata + Section->PointerToRawData, size);
if (size < Section->Misc.VirtualSize)
ZeroMem (base + size, Section->Misc.VirtualSize - size);
Section += 1;
}
efi_status = relocate_grub(&context, buffer);
if (efi_status != EFI_SUCCESS) {
Print(L"Relocation failed\n");
return efi_status;
}
entry_point = (void *)(context.EntryPoint + (UINT64)buffer);
return EFI_SUCCESS;
}
EFI_STATUS efi_main (EFI_HANDLE image_handle, EFI_SYSTEM_TABLE *passed_systab)
{
EFI_STATUS efi_status;
void *grubdata;
int grubsize;
systab = passed_systab;
InitializeLib(image_handle, systab);
efi_status = load_grub(image_handle, &grubdata, &grubsize);
if (efi_status != EFI_SUCCESS)
return efi_status;
efi_status = handle_grub(grubdata, grubsize);
if (efi_status != EFI_SUCCESS) {
Print(L"Failed to load grub\n");
return efi_status;
}
return uefi_call_wrapper(entry_point, 3, image_handle, passed_systab);
}
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