302 lines
11 KiB
C
302 lines
11 KiB
C
// ldr_image.c - PE32+ loader and export resolver
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//
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// At boot all images are already mapped by the bootloader; LdrLoadImage is
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// used for any image loaded later (currently unused - all modules come in via
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// BOOT_INFO). LdrGetExport scans the PE export directory of a registered module.
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#include "ldr_image.h"
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#include "boot_info.h"
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#include "mm_virt.h"
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#include "ke_debug.h"
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#include <string.h>
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#include <stdint.h>
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// ---------------------------------------------------------------------------
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// PE32+ structures (just what we need)
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// ---------------------------------------------------------------------------
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#define PE_SIGNATURE 0x00004550UL // 'PE\0\0'
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#define IMAGE_FILE_MACHINE_AMD64 0x8664
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#pragma pack(push, 1)
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typedef struct {
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uint16_t Magic;
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uint8_t MajorLinkerVersion;
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uint8_t MinorLinkerVersion;
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uint32_t SizeOfCode;
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uint32_t SizeOfInitializedData;
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uint32_t SizeOfUninitializedData;
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uint32_t AddressOfEntryPoint;
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uint32_t BaseOfCode;
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uint64_t ImageBase;
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uint32_t SectionAlignment;
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uint32_t FileAlignment;
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uint16_t MajorOSVersion;
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uint16_t MinorOSVersion;
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uint16_t MajorImageVersion;
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uint16_t MinorImageVersion;
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uint16_t MajorSubsystemVersion;
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uint16_t MinorSubsystemVersion;
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uint32_t Win32VersionValue;
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uint32_t SizeOfImage;
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uint32_t SizeOfHeaders;
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uint32_t CheckSum;
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uint16_t Subsystem;
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uint16_t DllCharacteristics;
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uint64_t SizeOfStackReserve;
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uint64_t SizeOfStackCommit;
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uint64_t SizeOfHeapReserve;
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uint64_t SizeOfHeapCommit;
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uint32_t LoaderFlags;
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uint32_t NumberOfRvaAndSizes;
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struct { uint32_t VirtualAddress; uint32_t Size; } DataDirectory[16];
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} OPT_HEADER64;
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typedef struct {
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uint32_t Signature;
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uint16_t Machine;
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uint16_t NumberOfSections;
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uint32_t TimeDateStamp;
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uint32_t PointerToSymbolTable;
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uint32_t NumberOfSymbols;
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uint16_t SizeOfOptionalHeader;
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uint16_t Characteristics;
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OPT_HEADER64 OptionalHeader;
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} PE_HEADER;
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typedef struct {
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char Name[8];
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uint32_t VirtualSize;
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uint32_t VirtualAddress;
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uint32_t SizeOfRawData;
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uint32_t PointerToRawData;
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uint32_t PointerToRelocations;
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uint32_t PointerToLinenumbers;
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uint16_t NumberOfRelocations;
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uint16_t NumberOfLinenumbers;
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uint32_t Characteristics;
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} SECTION_HEADER;
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typedef struct {
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uint32_t Characteristics;
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uint32_t TimeDateStamp;
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uint16_t MajorVersion;
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uint16_t MinorVersion;
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uint32_t Name;
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uint32_t Base;
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uint32_t NumberOfFunctions;
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uint32_t NumberOfNames;
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uint32_t AddressOfFunctions;
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uint32_t AddressOfNames;
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uint32_t AddressOfNameOrdinals;
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} EXPORT_DIR;
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typedef struct {
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uint32_t OriginalFirstThunk;
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uint32_t TimeDateStamp;
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uint32_t ForwarderChain;
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uint32_t Name;
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uint32_t FirstThunk;
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} IMPORT_DESC;
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typedef struct {
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uint32_t VirtualAddress;
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uint32_t SizeOfBlock;
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} BASE_RELOC;
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#pragma pack(pop)
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#define IMAGE_REL_BASED_DIR64 10
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// ---------------------------------------------------------------------------
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// Module registry
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// ---------------------------------------------------------------------------
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#define MAX_MODULES 32
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typedef struct {
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char Name[32];
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uintptr_t Base;
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} MODULE_ENTRY;
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static MODULE_ENTRY gModules[MAX_MODULES];
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static int gModuleCount = 0;
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void LdrRegisterModulesFromBootInfo(const BOOT_INFO* bootInfo) {
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for (uint32_t i = 0; i < bootInfo->ModuleCount && i < MAX_MODULES; i++) {
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strncpy(gModules[gModuleCount].Name, bootInfo->Modules[i].Name, 31);
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gModules[gModuleCount].Base = bootInfo->Modules[i].VirtBase;
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gModuleCount++;
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}
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}
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void LdrRegisterModule(const char* name, uintptr_t base) {
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if (gModuleCount < MAX_MODULES) {
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strncpy(gModules[gModuleCount].Name, name, 31);
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gModules[gModuleCount].Base = base;
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gModuleCount++;
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}
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}
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static uintptr_t FindModuleBase(const char* name) {
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for (int i = 0; i < gModuleCount; i++) {
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if (_stricmp(gModules[i].Name, name) == 0) return gModules[i].Base;
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}
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return 0;
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}
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// ---------------------------------------------------------------------------
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// Export lookup
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// ---------------------------------------------------------------------------
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void* LdrGetExport(const char* moduleName, const char* functionName) {
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uintptr_t base = FindModuleBase(moduleName);
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if (!base) return (void *)0;
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uint32_t peOffset = *(uint32_t *)(base + 0x3C);
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PE_HEADER* pe = (PE_HEADER *)(base + peOffset);
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if (pe->Signature != PE_SIGNATURE) return (void *)0;
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OPT_HEADER64* opt = &pe->OptionalHeader;
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if (opt->NumberOfRvaAndSizes < 1) return (void *)0;
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uint32_t expRva = opt->DataDirectory[0].VirtualAddress;
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if (!expRva) return (void *)0;
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EXPORT_DIR* exp = (EXPORT_DIR *)(base + expRva);
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uint32_t* names = (uint32_t *)(base + exp->AddressOfNames);
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uint16_t* ordinals = (uint16_t *)(base + exp->AddressOfNameOrdinals);
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uint32_t* functions = (uint32_t *)(base + exp->AddressOfFunctions);
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for (uint32_t i = 0; i < exp->NumberOfNames; i++) {
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const char* name = (const char *)(base + names[i]);
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if (strcmp(name, functionName) == 0) {
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uint16_t ord = ordinals[i];
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return (void *)(base + functions[ord]);
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}
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}
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return (void *)0;
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}
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// ---------------------------------------------------------------------------
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// Entry point lookup
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// ---------------------------------------------------------------------------
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uintptr_t LdrGetEntryPoint(uintptr_t base) {
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uint32_t pe_offset = *(uint32_t*)(base + 0x3C);
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uint32_t entry_rva = *(uint32_t*)(base + pe_offset + 0x28);
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return base + entry_rva;
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}
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// ---------------------------------------------------------------------------
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// Base Relocation
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// ---------------------------------------------------------------------------
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static KSTATUS LdrApplyRelocations(uintptr_t base, uintptr_t delta) {
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uint32_t peOffset = *(uint32_t *)(base + 0x3C);
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PE_HEADER* pe = (PE_HEADER *)(base + peOffset);
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OPT_HEADER64* opt = &pe->OptionalHeader;
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if (opt->NumberOfRvaAndSizes < 6) return STATUS_SUCCESS;
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uint32_t relocRva = opt->DataDirectory[5].VirtualAddress;
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uint32_t relocSize = opt->DataDirectory[5].Size;
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if (!relocRva || !relocSize) return STATUS_SUCCESS;
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BASE_RELOC* block = (BASE_RELOC *)(base + relocRva);
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uintptr_t end = (uintptr_t)block + relocSize;
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while ((uintptr_t)block < end && block->SizeOfBlock > 0) {
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uint32_t count = (block->SizeOfBlock - sizeof(BASE_RELOC)) / sizeof(uint16_t);
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uint16_t* entries = (uint16_t *)(block + 1);
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for (uint32_t i = 0; i < count; i++) {
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int type = entries[i] >> 12;
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int offset = entries[i] & 0xFFF;
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// For 64-bit PEs, we mostly care about DIR64 (Type 10)
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if (type == IMAGE_REL_BASED_DIR64) {
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uint64_t* ptr = (uint64_t *)(base + block->VirtualAddress + offset);
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*ptr += delta;
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}
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}
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block = (BASE_RELOC *)((uint8_t *)block + block->SizeOfBlock);
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}
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return STATUS_SUCCESS;
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}
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// ---------------------------------------------------------------------------
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// Import resolution
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// ---------------------------------------------------------------------------
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KSTATUS LdrResolveImports(uintptr_t imageBase) {
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uint32_t peOffset = *(uint32_t *)(imageBase + 0x3C);
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PE_HEADER* pe = (PE_HEADER *)(imageBase + peOffset);
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OPT_HEADER64* opt = &pe->OptionalHeader;
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if (opt->NumberOfRvaAndSizes < 2) return STATUS_SUCCESS; // no imports
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uint32_t impRva = opt->DataDirectory[1].VirtualAddress;
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if (!impRva) return STATUS_SUCCESS;
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IMPORT_DESC* imp = (IMPORT_DESC *)(imageBase + impRva);
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while (imp->Name) {
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const char* dllName = (const char *)(imageBase + imp->Name);
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uint64_t* thunk = (uint64_t *)(imageBase + imp->FirstThunk);
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uint64_t* origThunk = (uint64_t *)(imageBase + (imp->OriginalFirstThunk
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? imp->OriginalFirstThunk
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: imp->FirstThunk));
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while (*origThunk) {
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if (*origThunk & (1ULL << 63)) {
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// Import by ordinal - not supported.
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DbgPrint("LdrResolveImports: Ordinal imports not supported! (%s)\n", dllName);
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return STATUS_NOT_SUPPORTED;
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}
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const char* funcName = (const char *)(imageBase + (*origThunk & 0xFFFFFFFF) + 2);
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void* addr = LdrGetExport(dllName, funcName);
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if (!addr) {
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DbgPrint("LdrResolveImports: Function not found! (%s)\n", funcName);
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return STATUS_NOT_FOUND;
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}
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*thunk = (uint64_t)addr;
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thunk++;
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origThunk++;
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}
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imp++;
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}
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return STATUS_SUCCESS;
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}
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// LdrLoadImage - load a PE from a raw buffer into virtual space.
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KSTATUS LdrLoadImage(const void* buffer, size_t size, uintptr_t* baseOut, bool user) {
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if (!buffer || !size || !baseOut) return STATUS_INVALID_PARAMETER;
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uint32_t peOffset = *(uint32_t *)((uint8_t *)buffer + 0x3C);
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PE_HEADER* pe = (PE_HEADER *)((uint8_t *)buffer + peOffset);
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if (pe->Signature != PE_SIGNATURE) return STATUS_FAILURE;
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OPT_HEADER64* opt = &pe->OptionalHeader;
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size_t imageSize = opt->SizeOfImage;
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void* mem = user ? MmAllocateUserMemory(imageSize) : MmAllocatePool(imageSize);
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if (!mem) return STATUS_NO_MEMORY;
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memset(mem, 0, imageSize);
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// Copy headers and sections
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memcpy(mem, buffer, opt->SizeOfHeaders);
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SECTION_HEADER* sec = (SECTION_HEADER *)((uint8_t *)&pe->OptionalHeader + pe->SizeOfOptionalHeader);
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for (int i = 0; i < pe->NumberOfSections; i++) {
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void* dst = (uint8_t *)mem + sec[i].VirtualAddress;
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const void* src = (const uint8_t *)buffer + sec[i].PointerToRawData;
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if (sec[i].SizeOfRawData) {
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memcpy(dst, src, sec[i].SizeOfRawData < sec[i].VirtualSize ? sec[i].SizeOfRawData : sec[i].VirtualSize);
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}
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uint64_t prot = PAGE_PRESENT | PAGE_WRITE | (user ? PAGE_USER : 0);
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MmSetPageProtect((uintptr_t)mem + sec[i].VirtualAddress, sec[i].VirtualSize, prot);
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}
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// Apply Relocations
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uintptr_t delta = (uintptr_t)mem - opt->ImageBase;
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if (delta != 0) {
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LdrApplyRelocations((uintptr_t)mem, delta);
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}
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// Resolve Imports
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KSTATUS status = LdrResolveImports((uintptr_t)mem);
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if (status != STATUS_SUCCESS) return status;
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*baseOut = (uintptr_t)mem + opt->AddressOfEntryPoint;
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return STATUS_SUCCESS;
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}
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