//===-- interception_linux.cpp ----------------------------------*- C++ -*-===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This file is a part of AddressSanitizer, an address sanity checker. // // Windows-specific interception methods. // // This file is implementing several hooking techniques to intercept calls // to functions. The hooks are dynamically installed by modifying the assembly // code. // // The hooking techniques are making assumptions on the way the code is // generated and are safe under these assumptions. // // On 64-bit architecture, there is no direct 64-bit jump instruction. To allow // arbitrary branching on the whole memory space, the notion of trampoline // region is used. A trampoline region is a memory space withing 2G boundary // where it is safe to add custom assembly code to build 64-bit jumps. // // Hooking techniques // ================== // // 1) Detour // // The Detour hooking technique is assuming the presence of an header with // padding and an overridable 2-bytes nop instruction (mov edi, edi). The // nop instruction can safely be replaced by a 2-bytes jump without any need // to save the instruction. A jump to the target is encoded in the function // header and the nop instruction is replaced by a short jump to the header. // // head: 5 x nop head: jmp // func: mov edi, edi --> func: jmp short // [...] real: [...] // // This technique is only implemented on 32-bit architecture. // Most of the time, Windows API are hookable with the detour technique. // // 2) Redirect Jump // // The redirect jump is applicable when the first instruction is a direct // jump. The instruction is replaced by jump to the hook. // // func: jmp --> func: jmp // // On an 64-bit architecture, a trampoline is inserted. // // func: jmp --> func: jmp // [...] // // [trampoline] // tramp: jmp QWORD [addr] // addr: .bytes // // Note: is equivalent to . // // 3) HotPatch // // The HotPatch hooking is assuming the presence of an header with padding // and a first instruction with at least 2-bytes. // // The reason to enforce the 2-bytes limitation is to provide the minimal // space to encode a short jump. HotPatch technique is only rewriting one // instruction to avoid breaking a sequence of instructions containing a // branching target. // // Assumptions are enforced by MSVC compiler by using the /HOTPATCH flag. // see: https://msdn.microsoft.com/en-us/library/ms173507.aspx // Default padding length is 5 bytes in 32-bits and 6 bytes in 64-bits. // // head: 5 x nop head: jmp // func: --> func: jmp short // [...] body: [...] // // [trampoline] // real: // jmp // // On an 64-bit architecture: // // head: 6 x nop head: jmp QWORD [addr1] // func: --> func: jmp short // [...] body: [...] // // [trampoline] // addr1: .bytes // real: // jmp QWORD [addr2] // addr2: .bytes // // 4) Trampoline // // The Trampoline hooking technique is the most aggressive one. It is // assuming that there is a sequence of instructions that can be safely // replaced by a jump (enough room and no incoming branches). // // Unfortunately, these assumptions can't be safely presumed and code may // be broken after hooking. // // func: --> func: jmp // // [...] body: [...] // // [trampoline] // real: // // jmp // // On an 64-bit architecture: // // func: --> func: jmp QWORD [addr1] // // [...] body: [...] // // [trampoline] // addr1: .bytes // real: // // jmp QWORD [addr2] // addr2: .bytes //===----------------------------------------------------------------------===// #include "interception.h" #if SANITIZER_WINDOWS #include "sanitizer_common/sanitizer_platform.h" #define WIN32_LEAN_AND_MEAN #include namespace __interception { static const int kAddressLength = FIRST_32_SECOND_64(4, 8); static const int kJumpInstructionLength = 5; static const int kShortJumpInstructionLength = 2; UNUSED static const int kIndirectJumpInstructionLength = 6; static const int kBranchLength = FIRST_32_SECOND_64(kJumpInstructionLength, kIndirectJumpInstructionLength); static const int kDirectBranchLength = kBranchLength + kAddressLength; static void InterceptionFailed() { // Do we have a good way to abort with an error message here? __debugbreak(); } static bool DistanceIsWithin2Gig(uptr from, uptr target) { #if SANITIZER_WINDOWS64 if (from < target) return target - from <= (uptr)0x7FFFFFFFU; else return from - target <= (uptr)0x80000000U; #else // In a 32-bit address space, the address calculation will wrap, so this check // is unnecessary. return true; #endif } static uptr GetMmapGranularity() { SYSTEM_INFO si; GetSystemInfo(&si); return si.dwAllocationGranularity; } UNUSED static uptr RoundUpTo(uptr size, uptr boundary) { return (size + boundary - 1) & ~(boundary - 1); } // FIXME: internal_str* and internal_mem* functions should be moved from the // ASan sources into interception/. static size_t _strlen(const char *str) { const char* p = str; while (*p != '\0') ++p; return p - str; } static char* _strchr(char* str, char c) { while (*str) { if (*str == c) return str; ++str; } return nullptr; } static void _memset(void *p, int value, size_t sz) { for (size_t i = 0; i < sz; ++i) ((char*)p)[i] = (char)value; } static void _memcpy(void *dst, void *src, size_t sz) { char *dst_c = (char*)dst, *src_c = (char*)src; for (size_t i = 0; i < sz; ++i) dst_c[i] = src_c[i]; } static bool ChangeMemoryProtection( uptr address, uptr size, DWORD *old_protection) { return ::VirtualProtect((void*)address, size, PAGE_EXECUTE_READWRITE, old_protection) != FALSE; } static bool RestoreMemoryProtection( uptr address, uptr size, DWORD old_protection) { DWORD unused; return ::VirtualProtect((void*)address, size, old_protection, &unused) != FALSE; } static bool IsMemoryPadding(uptr address, uptr size) { u8* function = (u8*)address; for (size_t i = 0; i < size; ++i) if (function[i] != 0x90 && function[i] != 0xCC) return false; return true; } static const u8 kHintNop8Bytes[] = { 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00 }; template static bool FunctionHasPrefix(uptr address, const T &pattern) { u8* function = (u8*)address - sizeof(pattern); for (size_t i = 0; i < sizeof(pattern); ++i) if (function[i] != pattern[i]) return false; return true; } static bool FunctionHasPadding(uptr address, uptr size) { if (IsMemoryPadding(address - size, size)) return true; if (size <= sizeof(kHintNop8Bytes) && FunctionHasPrefix(address, kHintNop8Bytes)) return true; return false; } static void WritePadding(uptr from, uptr size) { _memset((void*)from, 0xCC, (size_t)size); } static void WriteJumpInstruction(uptr from, uptr target) { if (!DistanceIsWithin2Gig(from + kJumpInstructionLength, target)) InterceptionFailed(); ptrdiff_t offset = target - from - kJumpInstructionLength; *(u8*)from = 0xE9; *(u32*)(from + 1) = offset; } static void WriteShortJumpInstruction(uptr from, uptr target) { sptr offset = target - from - kShortJumpInstructionLength; if (offset < -128 || offset > 127) InterceptionFailed(); *(u8*)from = 0xEB; *(u8*)(from + 1) = (u8)offset; } #if SANITIZER_WINDOWS64 static void WriteIndirectJumpInstruction(uptr from, uptr indirect_target) { // jmp [rip + ] = FF 25 where is a relative // offset. // The offset is the distance from then end of the jump instruction to the // memory location containing the targeted address. The displacement is still // 32-bit in x64, so indirect_target must be located within +/- 2GB range. int offset = indirect_target - from - kIndirectJumpInstructionLength; if (!DistanceIsWithin2Gig(from + kIndirectJumpInstructionLength, indirect_target)) { InterceptionFailed(); } *(u16*)from = 0x25FF; *(u32*)(from + 2) = offset; } #endif static void WriteBranch( uptr from, uptr indirect_target, uptr target) { #if SANITIZER_WINDOWS64 WriteIndirectJumpInstruction(from, indirect_target); *(u64*)indirect_target = target; #else (void)indirect_target; WriteJumpInstruction(from, target); #endif } static void WriteDirectBranch(uptr from, uptr target) { #if SANITIZER_WINDOWS64 // Emit an indirect jump through immediately following bytes: // jmp [rip + kBranchLength] // .quad WriteBranch(from, from + kBranchLength, target); #else WriteJumpInstruction(from, target); #endif } struct TrampolineMemoryRegion { uptr content; uptr allocated_size; uptr max_size; }; UNUSED static const uptr kTrampolineScanLimitRange = 1 << 31; // 2 gig static const int kMaxTrampolineRegion = 1024; static TrampolineMemoryRegion TrampolineRegions[kMaxTrampolineRegion]; static void *AllocateTrampolineRegion(uptr image_address, size_t granularity) { #if SANITIZER_WINDOWS64 uptr address = image_address; uptr scanned = 0; while (scanned < kTrampolineScanLimitRange) { MEMORY_BASIC_INFORMATION info; if (!::VirtualQuery((void*)address, &info, sizeof(info))) return nullptr; // Check whether a region can be allocated at |address|. if (info.State == MEM_FREE && info.RegionSize >= granularity) { void *page = ::VirtualAlloc((void*)RoundUpTo(address, granularity), granularity, MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE); return page; } // Move to the next region. address = (uptr)info.BaseAddress + info.RegionSize; scanned += info.RegionSize; } return nullptr; #else return ::VirtualAlloc(nullptr, granularity, MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE); #endif } // Used by unittests to release mapped memory space. void TestOnlyReleaseTrampolineRegions() { for (size_t bucket = 0; bucket < kMaxTrampolineRegion; ++bucket) { TrampolineMemoryRegion *current = &TrampolineRegions[bucket]; if (current->content == 0) return; ::VirtualFree((void*)current->content, 0, MEM_RELEASE); current->content = 0; } } static uptr AllocateMemoryForTrampoline(uptr image_address, size_t size) { // Find a region within 2G with enough space to allocate |size| bytes. TrampolineMemoryRegion *region = nullptr; for (size_t bucket = 0; bucket < kMaxTrampolineRegion; ++bucket) { TrampolineMemoryRegion* current = &TrampolineRegions[bucket]; if (current->content == 0) { // No valid region found, allocate a new region. size_t bucket_size = GetMmapGranularity(); void *content = AllocateTrampolineRegion(image_address, bucket_size); if (content == nullptr) return 0U; current->content = (uptr)content; current->allocated_size = 0; current->max_size = bucket_size; region = current; break; } else if (current->max_size - current->allocated_size > size) { #if SANITIZER_WINDOWS64 // In 64-bits, the memory space must be allocated within 2G boundary. uptr next_address = current->content + current->allocated_size; if (next_address < image_address || next_address - image_address >= 0x7FFF0000) continue; #endif // The space can be allocated in the current region. region = current; break; } } // Failed to find a region. if (region == nullptr) return 0U; // Allocate the space in the current region. uptr allocated_space = region->content + region->allocated_size; region->allocated_size += size; WritePadding(allocated_space, size); return allocated_space; } // The following prologues cannot be patched because of the short jump // jumping to the patching region. // ntdll!wcslen in Win11 // 488bc1 mov rax,rcx // 0fb710 movzx edx,word ptr [rax] // 4883c002 add rax,2 // 6685d2 test dx,dx // 75f4 jne -12 static const u8 kPrologueWithShortJump1[] = { 0x48, 0x8b, 0xc1, 0x0f, 0xb7, 0x10, 0x48, 0x83, 0xc0, 0x02, 0x66, 0x85, 0xd2, 0x75, 0xf4, }; // ntdll!strrchr in Win11 // 4c8bc1 mov r8,rcx // 8a01 mov al,byte ptr [rcx] // 48ffc1 inc rcx // 84c0 test al,al // 75f7 jne -9 static const u8 kPrologueWithShortJump2[] = { 0x4c, 0x8b, 0xc1, 0x8a, 0x01, 0x48, 0xff, 0xc1, 0x84, 0xc0, 0x75, 0xf7, }; // Returns 0 on error. static size_t GetInstructionSize(uptr address, size_t* rel_offset = nullptr) { #if SANITIZER_WINDOWS64 if (memcmp((u8*)address, kPrologueWithShortJump1, sizeof(kPrologueWithShortJump1)) == 0 || memcmp((u8*)address, kPrologueWithShortJump2, sizeof(kPrologueWithShortJump2)) == 0) { return 0; } #endif switch (*(u64*)address) { case 0x90909090909006EB: // stub: jmp over 6 x nop. return 8; } switch (*(u8*)address) { case 0x90: // 90 : nop return 1; case 0x50: // push eax / rax case 0x51: // push ecx / rcx case 0x52: // push edx / rdx case 0x53: // push ebx / rbx case 0x54: // push esp / rsp case 0x55: // push ebp / rbp case 0x56: // push esi / rsi case 0x57: // push edi / rdi case 0x5D: // pop ebp / rbp return 1; case 0x6A: // 6A XX = push XX return 2; case 0xb8: // b8 XX XX XX XX : mov eax, XX XX XX XX case 0xB9: // b9 XX XX XX XX : mov ecx, XX XX XX XX return 5; // Cannot overwrite control-instruction. Return 0 to indicate failure. case 0xE9: // E9 XX XX XX XX : jmp case 0xE8: // E8 XX XX XX XX : call case 0xC3: // C3 : ret case 0xEB: // EB XX : jmp XX (short jump) case 0x70: // 7Y YY : jy XX (short conditional jump) case 0x71: case 0x72: case 0x73: case 0x74: case 0x75: case 0x76: case 0x77: case 0x78: case 0x79: case 0x7A: case 0x7B: case 0x7C: case 0x7D: case 0x7E: case 0x7F: return 0; } switch (*(u16*)(address)) { case 0x018A: // 8A 01 : mov al, byte ptr [ecx] case 0xFF8B: // 8B FF : mov edi, edi case 0xEC8B: // 8B EC : mov ebp, esp case 0xc889: // 89 C8 : mov eax, ecx case 0xC18B: // 8B C1 : mov eax, ecx case 0xC033: // 33 C0 : xor eax, eax case 0xC933: // 33 C9 : xor ecx, ecx case 0xD233: // 33 D2 : xor edx, edx return 2; // Cannot overwrite control-instruction. Return 0 to indicate failure. case 0x25FF: // FF 25 XX XX XX XX : jmp [XXXXXXXX] return 0; } switch (0x00FFFFFF & *(u32*)address) { case 0x24A48D: // 8D A4 24 XX XX XX XX : lea esp, [esp + XX XX XX XX] return 7; } #if SANITIZER_WINDOWS64 switch (*(u8*)address) { case 0xA1: // A1 XX XX XX XX XX XX XX XX : // movabs eax, dword ptr ds:[XXXXXXXX] return 9; case 0x83: const u8 next_byte = *(u8*)(address + 1); const u8 mod = next_byte >> 6; const u8 rm = next_byte & 7; if (mod == 1 && rm == 4) return 5; // 83 ModR/M SIB Disp8 Imm8 // add|or|adc|sbb|and|sub|xor|cmp [r+disp8], imm8 } switch (*(u16*)address) { case 0x5040: // push rax case 0x5140: // push rcx case 0x5240: // push rdx case 0x5340: // push rbx case 0x5440: // push rsp case 0x5540: // push rbp case 0x5640: // push rsi case 0x5740: // push rdi case 0x5441: // push r12 case 0x5541: // push r13 case 0x5641: // push r14 case 0x5741: // push r15 case 0x9066: // Two-byte NOP case 0xc084: // test al, al case 0x018a: // mov al, byte ptr [rcx] return 2; case 0x058B: // 8B 05 XX XX XX XX : mov eax, dword ptr [XX XX XX XX] if (rel_offset) *rel_offset = 2; return 6; } switch (0x00FFFFFF & *(u32*)address) { case 0xe58948: // 48 8b c4 : mov rbp, rsp case 0xc18b48: // 48 8b c1 : mov rax, rcx case 0xc48b48: // 48 8b c4 : mov rax, rsp case 0xd9f748: // 48 f7 d9 : neg rcx case 0xd12b48: // 48 2b d1 : sub rdx, rcx case 0x07c1f6: // f6 c1 07 : test cl, 0x7 case 0xc98548: // 48 85 C9 : test rcx, rcx case 0xd28548: // 48 85 d2 : test rdx, rdx case 0xc0854d: // 4d 85 c0 : test r8, r8 case 0xc2b60f: // 0f b6 c2 : movzx eax, dl case 0xc03345: // 45 33 c0 : xor r8d, r8d case 0xc93345: // 45 33 c9 : xor r9d, r9d case 0xdb3345: // 45 33 DB : xor r11d, r11d case 0xd98b4c: // 4c 8b d9 : mov r11, rcx case 0xd28b4c: // 4c 8b d2 : mov r10, rdx case 0xc98b4c: // 4C 8B C9 : mov r9, rcx case 0xc18b4c: // 4C 8B C1 : mov r8, rcx case 0xd2b60f: // 0f b6 d2 : movzx edx, dl case 0xca2b48: // 48 2b ca : sub rcx, rdx case 0x10b70f: // 0f b7 10 : movzx edx, WORD PTR [rax] case 0xc00b4d: // 3d 0b c0 : or r8, r8 case 0xc08b41: // 41 8b c0 : mov eax, r8d case 0xd18b48: // 48 8b d1 : mov rdx, rcx case 0xdc8b4c: // 4c 8b dc : mov r11, rsp case 0xd18b4c: // 4c 8b d1 : mov r10, rcx case 0xE0E483: // 83 E4 E0 : and esp, 0xFFFFFFE0 return 3; case 0xec8348: // 48 83 ec XX : sub rsp, XX case 0xf88349: // 49 83 f8 XX : cmp r8, XX case 0x588948: // 48 89 58 XX : mov QWORD PTR[rax + XX], rbx return 4; case 0xec8148: // 48 81 EC XX XX XX XX : sub rsp, XXXXXXXX return 7; case 0x058b48: // 48 8b 05 XX XX XX XX : // mov rax, QWORD PTR [rip + XXXXXXXX] case 0x25ff48: // 48 ff 25 XX XX XX XX : // rex.W jmp QWORD PTR [rip + XXXXXXXX] // Instructions having offset relative to 'rip' need offset adjustment. if (rel_offset) *rel_offset = 3; return 7; case 0x2444c7: // C7 44 24 XX YY YY YY YY // mov dword ptr [rsp + XX], YYYYYYYY return 8; } switch (*(u32*)(address)) { case 0x24448b48: // 48 8b 44 24 XX : mov rax, QWORD ptr [rsp + XX] case 0x246c8948: // 48 89 6C 24 XX : mov QWORD ptr [rsp + XX], rbp case 0x245c8948: // 48 89 5c 24 XX : mov QWORD PTR [rsp + XX], rbx case 0x24748948: // 48 89 74 24 XX : mov QWORD PTR [rsp + XX], rsi case 0x244C8948: // 48 89 4C 24 XX : mov QWORD PTR [rsp + XX], rcx case 0x24548948: // 48 89 54 24 XX : mov QWORD PTR [rsp + XX], rdx case 0x244c894c: // 4c 89 4c 24 XX : mov QWORD PTR [rsp + XX], r9 case 0x2444894c: // 4c 89 44 24 XX : mov QWORD PTR [rsp + XX], r8 return 5; case 0x24648348: // 48 83 64 24 XX : and QWORD PTR [rsp + XX], YY return 6; } #else switch (*(u8*)address) { case 0xA1: // A1 XX XX XX XX : mov eax, dword ptr ds:[XXXXXXXX] return 5; } switch (*(u16*)address) { case 0x458B: // 8B 45 XX : mov eax, dword ptr [ebp + XX] case 0x5D8B: // 8B 5D XX : mov ebx, dword ptr [ebp + XX] case 0x7D8B: // 8B 7D XX : mov edi, dword ptr [ebp + XX] case 0xEC83: // 83 EC XX : sub esp, XX case 0x75FF: // FF 75 XX : push dword ptr [ebp + XX] return 3; case 0xC1F7: // F7 C1 XX YY ZZ WW : test ecx, WWZZYYXX case 0x25FF: // FF 25 XX YY ZZ WW : jmp dword ptr ds:[WWZZYYXX] return 6; case 0x3D83: // 83 3D XX YY ZZ WW TT : cmp TT, WWZZYYXX return 7; case 0x7D83: // 83 7D XX YY : cmp dword ptr [ebp + XX], YY return 4; } switch (0x00FFFFFF & *(u32*)address) { case 0x24448A: // 8A 44 24 XX : mov eal, dword ptr [esp + XX] case 0x24448B: // 8B 44 24 XX : mov eax, dword ptr [esp + XX] case 0x244C8B: // 8B 4C 24 XX : mov ecx, dword ptr [esp + XX] case 0x24548B: // 8B 54 24 XX : mov edx, dword ptr [esp + XX] case 0x24748B: // 8B 74 24 XX : mov esi, dword ptr [esp + XX] case 0x247C8B: // 8B 7C 24 XX : mov edi, dword ptr [esp + XX] return 4; } switch (*(u32*)address) { case 0x2444B60F: // 0F B6 44 24 XX : movzx eax, byte ptr [esp + XX] return 5; } #endif // Unknown instruction! // FIXME: Unknown instruction failures might happen when we add a new // interceptor or a new compiler version. In either case, they should result // in visible and readable error messages. However, merely calling abort() // leads to an infinite recursion in CheckFailed. InterceptionFailed(); return 0; } // Returns 0 on error. static size_t RoundUpToInstrBoundary(size_t size, uptr address) { size_t cursor = 0; while (cursor < size) { size_t instruction_size = GetInstructionSize(address + cursor); if (!instruction_size) return 0; cursor += instruction_size; } return cursor; } static bool CopyInstructions(uptr to, uptr from, size_t size) { size_t cursor = 0; while (cursor != size) { size_t rel_offset = 0; size_t instruction_size = GetInstructionSize(from + cursor, &rel_offset); _memcpy((void*)(to + cursor), (void*)(from + cursor), (size_t)instruction_size); if (rel_offset) { uptr delta = to - from; uptr relocated_offset = *(u32*)(to + cursor + rel_offset) - delta; #if SANITIZER_WINDOWS64 if (relocated_offset + 0x80000000U >= 0xFFFFFFFFU) return false; #endif *(u32*)(to + cursor + rel_offset) = relocated_offset; } cursor += instruction_size; } return true; } #if !SANITIZER_WINDOWS64 bool OverrideFunctionWithDetour( uptr old_func, uptr new_func, uptr *orig_old_func) { const int kDetourHeaderLen = 5; const u16 kDetourInstruction = 0xFF8B; uptr header = (uptr)old_func - kDetourHeaderLen; uptr patch_length = kDetourHeaderLen + kShortJumpInstructionLength; // Validate that the function is hookable. if (*(u16*)old_func != kDetourInstruction || !IsMemoryPadding(header, kDetourHeaderLen)) return false; // Change memory protection to writable. DWORD protection = 0; if (!ChangeMemoryProtection(header, patch_length, &protection)) return false; // Write a relative jump to the redirected function. WriteJumpInstruction(header, new_func); // Write the short jump to the function prefix. WriteShortJumpInstruction(old_func, header); // Restore previous memory protection. if (!RestoreMemoryProtection(header, patch_length, protection)) return false; if (orig_old_func) *orig_old_func = old_func + kShortJumpInstructionLength; return true; } #endif bool OverrideFunctionWithRedirectJump( uptr old_func, uptr new_func, uptr *orig_old_func) { // Check whether the first instruction is a relative jump. if (*(u8*)old_func != 0xE9) return false; if (orig_old_func) { uptr relative_offset = *(u32*)(old_func + 1); uptr absolute_target = old_func + relative_offset + kJumpInstructionLength; *orig_old_func = absolute_target; } #if SANITIZER_WINDOWS64 // If needed, get memory space for a trampoline jump. uptr trampoline = AllocateMemoryForTrampoline(old_func, kDirectBranchLength); if (!trampoline) return false; WriteDirectBranch(trampoline, new_func); #endif // Change memory protection to writable. DWORD protection = 0; if (!ChangeMemoryProtection(old_func, kJumpInstructionLength, &protection)) return false; // Write a relative jump to the redirected function. WriteJumpInstruction(old_func, FIRST_32_SECOND_64(new_func, trampoline)); // Restore previous memory protection. if (!RestoreMemoryProtection(old_func, kJumpInstructionLength, protection)) return false; return true; } bool OverrideFunctionWithHotPatch( uptr old_func, uptr new_func, uptr *orig_old_func) { const int kHotPatchHeaderLen = kBranchLength; uptr header = (uptr)old_func - kHotPatchHeaderLen; uptr patch_length = kHotPatchHeaderLen + kShortJumpInstructionLength; // Validate that the function is hot patchable. size_t instruction_size = GetInstructionSize(old_func); if (instruction_size < kShortJumpInstructionLength || !FunctionHasPadding(old_func, kHotPatchHeaderLen)) return false; if (orig_old_func) { // Put the needed instructions into the trampoline bytes. uptr trampoline_length = instruction_size + kDirectBranchLength; uptr trampoline = AllocateMemoryForTrampoline(old_func, trampoline_length); if (!trampoline) return false; if (!CopyInstructions(trampoline, old_func, instruction_size)) return false; WriteDirectBranch(trampoline + instruction_size, old_func + instruction_size); *orig_old_func = trampoline; } // If needed, get memory space for indirect address. uptr indirect_address = 0; #if SANITIZER_WINDOWS64 indirect_address = AllocateMemoryForTrampoline(old_func, kAddressLength); if (!indirect_address) return false; #endif // Change memory protection to writable. DWORD protection = 0; if (!ChangeMemoryProtection(header, patch_length, &protection)) return false; // Write jumps to the redirected function. WriteBranch(header, indirect_address, new_func); WriteShortJumpInstruction(old_func, header); // Restore previous memory protection. if (!RestoreMemoryProtection(header, patch_length, protection)) return false; return true; } bool OverrideFunctionWithTrampoline( uptr old_func, uptr new_func, uptr *orig_old_func) { size_t instructions_length = kBranchLength; size_t padding_length = 0; uptr indirect_address = 0; if (orig_old_func) { // Find out the number of bytes of the instructions we need to copy // to the trampoline. instructions_length = RoundUpToInstrBoundary(kBranchLength, old_func); if (!instructions_length) return false; // Put the needed instructions into the trampoline bytes. uptr trampoline_length = instructions_length + kDirectBranchLength; uptr trampoline = AllocateMemoryForTrampoline(old_func, trampoline_length); if (!trampoline) return false; if (!CopyInstructions(trampoline, old_func, instructions_length)) return false; WriteDirectBranch(trampoline + instructions_length, old_func + instructions_length); *orig_old_func = trampoline; } #if SANITIZER_WINDOWS64 // Check if the targeted address can be encoded in the function padding. // Otherwise, allocate it in the trampoline region. if (IsMemoryPadding(old_func - kAddressLength, kAddressLength)) { indirect_address = old_func - kAddressLength; padding_length = kAddressLength; } else { indirect_address = AllocateMemoryForTrampoline(old_func, kAddressLength); if (!indirect_address) return false; } #endif // Change memory protection to writable. uptr patch_address = old_func - padding_length; uptr patch_length = instructions_length + padding_length; DWORD protection = 0; if (!ChangeMemoryProtection(patch_address, patch_length, &protection)) return false; // Patch the original function. WriteBranch(old_func, indirect_address, new_func); // Restore previous memory protection. if (!RestoreMemoryProtection(patch_address, patch_length, protection)) return false; return true; } bool OverrideFunction( uptr old_func, uptr new_func, uptr *orig_old_func) { #if !SANITIZER_WINDOWS64 if (OverrideFunctionWithDetour(old_func, new_func, orig_old_func)) return true; #endif if (OverrideFunctionWithRedirectJump(old_func, new_func, orig_old_func)) return true; if (OverrideFunctionWithHotPatch(old_func, new_func, orig_old_func)) return true; if (OverrideFunctionWithTrampoline(old_func, new_func, orig_old_func)) return true; return false; } static void **InterestingDLLsAvailable() { static const char *InterestingDLLs[] = { "kernel32.dll", "msvcr100.dll", // VS2010 "msvcr110.dll", // VS2012 "msvcr120.dll", // VS2013 "vcruntime140.dll", // VS2015 "ucrtbase.dll", // Universal CRT // NTDLL should go last as it exports some functions that we should // override in the CRT [presumably only used internally]. "ntdll.dll", NULL}; static void *result[ARRAY_SIZE(InterestingDLLs)] = { 0 }; if (!result[0]) { for (size_t i = 0, j = 0; InterestingDLLs[i]; ++i) { if (HMODULE h = GetModuleHandleA(InterestingDLLs[i])) result[j++] = (void *)h; } } return &result[0]; } namespace { // Utility for reading loaded PE images. template class RVAPtr { public: RVAPtr(void *module, uptr rva) : ptr_(reinterpret_cast(reinterpret_cast(module) + rva)) {} operator T *() { return ptr_; } T *operator->() { return ptr_; } T *operator++() { return ++ptr_; } private: T *ptr_; }; } // namespace // Internal implementation of GetProcAddress. At least since Windows 8, // GetProcAddress appears to initialize DLLs before returning function pointers // into them. This is problematic for the sanitizers, because they typically // want to intercept malloc *before* MSVCRT initializes. Our internal // implementation walks the export list manually without doing initialization. uptr InternalGetProcAddress(void *module, const char *func_name) { // Check that the module header is full and present. RVAPtr dos_stub(module, 0); RVAPtr headers(module, dos_stub->e_lfanew); if (!module || dos_stub->e_magic != IMAGE_DOS_SIGNATURE || // "MZ" headers->Signature != IMAGE_NT_SIGNATURE || // "PE\0\0" headers->FileHeader.SizeOfOptionalHeader < sizeof(IMAGE_OPTIONAL_HEADER)) { return 0; } IMAGE_DATA_DIRECTORY *export_directory = &headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT]; if (export_directory->Size == 0) return 0; RVAPtr exports(module, export_directory->VirtualAddress); RVAPtr functions(module, exports->AddressOfFunctions); RVAPtr names(module, exports->AddressOfNames); RVAPtr ordinals(module, exports->AddressOfNameOrdinals); for (DWORD i = 0; i < exports->NumberOfNames; i++) { RVAPtr name(module, names[i]); if (!strcmp(func_name, name)) { DWORD index = ordinals[i]; RVAPtr func(module, functions[index]); // Handle forwarded functions. DWORD offset = functions[index]; if (offset >= export_directory->VirtualAddress && offset < export_directory->VirtualAddress + export_directory->Size) { // An entry for a forwarded function is a string with the following // format: " . " that is stored into the // exported directory. char function_name[256]; size_t funtion_name_length = _strlen(func); if (funtion_name_length >= sizeof(function_name) - 1) InterceptionFailed(); _memcpy(function_name, func, funtion_name_length); function_name[funtion_name_length] = '\0'; char* separator = _strchr(function_name, '.'); if (!separator) InterceptionFailed(); *separator = '\0'; void* redirected_module = GetModuleHandleA(function_name); if (!redirected_module) InterceptionFailed(); return InternalGetProcAddress(redirected_module, separator + 1); } return (uptr)(char *)func; } } return 0; } bool OverrideFunction( const char *func_name, uptr new_func, uptr *orig_old_func) { bool hooked = false; void **DLLs = InterestingDLLsAvailable(); for (size_t i = 0; DLLs[i]; ++i) { uptr func_addr = InternalGetProcAddress(DLLs[i], func_name); if (func_addr && OverrideFunction(func_addr, new_func, orig_old_func)) { hooked = true; } } return hooked; } bool OverrideImportedFunction(const char *module_to_patch, const char *imported_module, const char *function_name, uptr new_function, uptr *orig_old_func) { HMODULE module = GetModuleHandleA(module_to_patch); if (!module) return false; // Check that the module header is full and present. RVAPtr dos_stub(module, 0); RVAPtr headers(module, dos_stub->e_lfanew); if (!module || dos_stub->e_magic != IMAGE_DOS_SIGNATURE || // "MZ" headers->Signature != IMAGE_NT_SIGNATURE || // "PE\0\0" headers->FileHeader.SizeOfOptionalHeader < sizeof(IMAGE_OPTIONAL_HEADER)) { return false; } IMAGE_DATA_DIRECTORY *import_directory = &headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT]; // Iterate the list of imported DLLs. FirstThunk will be null for the last // entry. RVAPtr imports(module, import_directory->VirtualAddress); for (; imports->FirstThunk != 0; ++imports) { RVAPtr modname(module, imports->Name); if (_stricmp(&*modname, imported_module) == 0) break; } if (imports->FirstThunk == 0) return false; // We have two parallel arrays: the import address table (IAT) and the table // of names. They start out containing the same data, but the loader rewrites // the IAT to hold imported addresses and leaves the name table in // OriginalFirstThunk alone. RVAPtr name_table(module, imports->OriginalFirstThunk); RVAPtr iat(module, imports->FirstThunk); for (; name_table->u1.Ordinal != 0; ++name_table, ++iat) { if (!IMAGE_SNAP_BY_ORDINAL(name_table->u1.Ordinal)) { RVAPtr import_by_name( module, name_table->u1.ForwarderString); const char *funcname = &import_by_name->Name[0]; if (strcmp(funcname, function_name) == 0) break; } } if (name_table->u1.Ordinal == 0) return false; // Now we have the correct IAT entry. Do the swap. We have to make the page // read/write first. if (orig_old_func) *orig_old_func = iat->u1.AddressOfData; DWORD old_prot, unused_prot; if (!VirtualProtect(&iat->u1.AddressOfData, 4, PAGE_EXECUTE_READWRITE, &old_prot)) return false; iat->u1.AddressOfData = new_function; if (!VirtualProtect(&iat->u1.AddressOfData, 4, old_prot, &unused_prot)) return false; // Not clear if this failure bothers us. return true; } } // namespace __interception #endif // SANITIZER_MAC