1 //===-- interception_linux.cc -----------------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
12 // Windows-specific interception methods.
14 // This file is implementing several hooking techniques to intercept calls
15 // to functions. The hooks are dynamically installed by modifying the assembly
18 // The hooking techniques are making assumptions on the way the code is
19 // generated and are safe under these assumptions.
21 // On 64-bit architecture, there is no direct 64-bit jump instruction. To allow
22 // arbitrary branching on the whole memory space, the notion of trampoline
23 // region is used. A trampoline region is a memory space withing 2G boundary
24 // where it is safe to add custom assembly code to build 64-bit jumps.
31 // The Detour hooking technique is assuming the presence of an header with
32 // padding and an overridable 2-bytes nop instruction (mov edi, edi). The
33 // nop instruction can safely be replaced by a 2-bytes jump without any need
34 // to save the instruction. A jump to the target is encoded in the function
35 // header and the nop instruction is replaced by a short jump to the header.
37 // head: 5 x nop head: jmp <hook>
38 // func: mov edi, edi --> func: jmp short <head>
41 // This technique is only implemented on 32-bit architecture.
42 // Most of the time, Windows API are hookable with the detour technique.
46 // The redirect jump is applicable when the first instruction is a direct
47 // jump. The instruction is replaced by jump to the hook.
49 // func: jmp <label> --> func: jmp <hook>
51 // On an 64-bit architecture, a trampoline is inserted.
53 // func: jmp <label> --> func: jmp <tramp>
57 // tramp: jmp QWORD [addr]
58 // addr: .bytes <hook>
60 // Note: <real> is equilavent to <label>.
64 // The HotPatch hooking is assuming the presence of an header with padding
65 // and a first instruction with at least 2-bytes.
67 // The reason to enforce the 2-bytes limitation is to provide the minimal
68 // space to encode a short jump. HotPatch technique is only rewriting one
69 // instruction to avoid breaking a sequence of instructions containing a
72 // Assumptions are enforced by MSVC compiler by using the /HOTPATCH flag.
73 // see: https://msdn.microsoft.com/en-us/library/ms173507.aspx
74 // Default padding length is 5 bytes in 32-bits and 6 bytes in 64-bits.
76 // head: 5 x nop head: jmp <hook>
77 // func: <instr> --> func: jmp short <head>
84 // On an 64-bit architecture:
86 // head: 6 x nop head: jmp QWORD [addr1]
87 // func: <instr> --> func: jmp short <head>
91 // addr1: .bytes <hook>
94 // addr2: .bytes <body>
98 // The Trampoline hooking technique is the most aggressive one. It is
99 // assuming that there is a sequence of instructions that can be safely
100 // replaced by a jump (enough room and no incoming branches).
102 // Unfortunately, these assumptions can't be safely presumed and code may
103 // be broken after hooking.
105 // func: <instr> --> func: jmp <hook>
114 // On an 64-bit architecture:
116 // func: <instr> --> func: jmp QWORD [addr1]
121 // addr1: .bytes <hook>
125 // addr2: .bytes <body>
126 //===----------------------------------------------------------------------===//
128 #include "interception.h"
130 #if SANITIZER_WINDOWS
131 #include "sanitizer_common/sanitizer_platform.h"
132 #define WIN32_LEAN_AND_MEAN
135 namespace __interception {
137 static const int kAddressLength = FIRST_32_SECOND_64(4, 8);
138 static const int kJumpInstructionLength = 5;
139 static const int kShortJumpInstructionLength = 2;
140 static const int kIndirectJumpInstructionLength = 6;
141 static const int kBranchLength =
142 FIRST_32_SECOND_64(kJumpInstructionLength, kIndirectJumpInstructionLength);
143 static const int kDirectBranchLength = kBranchLength + kAddressLength;
145 static void InterceptionFailed() {
146 // Do we have a good way to abort with an error message here?
150 static bool DistanceIsWithin2Gig(uptr from, uptr target) {
151 #if SANITIZER_WINDOWS64
153 return target - from <= (uptr)0x7FFFFFFFU;
155 return from - target <= (uptr)0x80000000U;
157 // In a 32-bit address space, the address calculation will wrap, so this check
163 static uptr GetMmapGranularity() {
166 return si.dwAllocationGranularity;
169 static uptr RoundUpTo(uptr size, uptr boundary) {
170 return (size + boundary - 1) & ~(boundary - 1);
173 // FIXME: internal_str* and internal_mem* functions should be moved from the
174 // ASan sources into interception/.
176 static size_t _strlen(const char *str) {
178 while (*p != '\0') ++p;
182 static char* _strchr(char* str, char c) {
191 static void _memset(void *p, int value, size_t sz) {
192 for (size_t i = 0; i < sz; ++i)
193 ((char*)p)[i] = (char)value;
196 static void _memcpy(void *dst, void *src, size_t sz) {
197 char *dst_c = (char*)dst,
199 for (size_t i = 0; i < sz; ++i)
203 static bool ChangeMemoryProtection(
204 uptr address, uptr size, DWORD *old_protection) {
205 return ::VirtualProtect((void*)address, size,
206 PAGE_EXECUTE_READWRITE,
207 old_protection) != FALSE;
210 static bool RestoreMemoryProtection(
211 uptr address, uptr size, DWORD old_protection) {
213 return ::VirtualProtect((void*)address, size,
218 static bool IsMemoryPadding(uptr address, uptr size) {
219 u8* function = (u8*)address;
220 for (size_t i = 0; i < size; ++i)
221 if (function[i] != 0x90 && function[i] != 0xCC)
226 static const u8 kHintNop9Bytes[] = {
227 0x66, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00
231 static bool FunctionHasPrefix(uptr address, const T &pattern) {
232 u8* function = (u8*)address - sizeof(pattern);
233 for (size_t i = 0; i < sizeof(pattern); ++i)
234 if (function[i] != pattern[i])
239 static bool FunctionHasPadding(uptr address, uptr size) {
240 if (IsMemoryPadding(address - size, size))
242 if (size <= sizeof(kHintNop9Bytes) &&
243 FunctionHasPrefix(address, kHintNop9Bytes))
248 static void WritePadding(uptr from, uptr size) {
249 _memset((void*)from, 0xCC, (size_t)size);
252 static void WriteJumpInstruction(uptr from, uptr target) {
253 if (!DistanceIsWithin2Gig(from + kJumpInstructionLength, target))
254 InterceptionFailed();
255 ptrdiff_t offset = target - from - kJumpInstructionLength;
257 *(u32*)(from + 1) = offset;
260 static void WriteShortJumpInstruction(uptr from, uptr target) {
261 sptr offset = target - from - kShortJumpInstructionLength;
262 if (offset < -128 || offset > 127)
263 InterceptionFailed();
265 *(u8*)(from + 1) = (u8)offset;
268 #if SANITIZER_WINDOWS64
269 static void WriteIndirectJumpInstruction(uptr from, uptr indirect_target) {
270 // jmp [rip + <offset>] = FF 25 <offset> where <offset> is a relative
272 // The offset is the distance from then end of the jump instruction to the
273 // memory location containing the targeted address. The displacement is still
274 // 32-bit in x64, so indirect_target must be located within +/- 2GB range.
275 int offset = indirect_target - from - kIndirectJumpInstructionLength;
276 if (!DistanceIsWithin2Gig(from + kIndirectJumpInstructionLength,
278 InterceptionFailed();
280 *(u16*)from = 0x25FF;
281 *(u32*)(from + 2) = offset;
285 static void WriteBranch(
286 uptr from, uptr indirect_target, uptr target) {
287 #if SANITIZER_WINDOWS64
288 WriteIndirectJumpInstruction(from, indirect_target);
289 *(u64*)indirect_target = target;
291 (void)indirect_target;
292 WriteJumpInstruction(from, target);
296 static void WriteDirectBranch(uptr from, uptr target) {
297 #if SANITIZER_WINDOWS64
298 // Emit an indirect jump through immediately following bytes:
299 // jmp [rip + kBranchLength]
301 WriteBranch(from, from + kBranchLength, target);
303 WriteJumpInstruction(from, target);
307 struct TrampolineMemoryRegion {
313 static const uptr kTrampolineScanLimitRange = 1 << 31; // 2 gig
314 static const int kMaxTrampolineRegion = 1024;
315 static TrampolineMemoryRegion TrampolineRegions[kMaxTrampolineRegion];
317 static void *AllocateTrampolineRegion(uptr image_address, size_t granularity) {
318 #if SANITIZER_WINDOWS64
319 uptr address = image_address;
321 while (scanned < kTrampolineScanLimitRange) {
322 MEMORY_BASIC_INFORMATION info;
323 if (!::VirtualQuery((void*)address, &info, sizeof(info)))
326 // Check whether a region can be allocated at |address|.
327 if (info.State == MEM_FREE && info.RegionSize >= granularity) {
328 void *page = ::VirtualAlloc((void*)RoundUpTo(address, granularity),
330 MEM_RESERVE | MEM_COMMIT,
331 PAGE_EXECUTE_READWRITE);
335 // Move to the next region.
336 address = (uptr)info.BaseAddress + info.RegionSize;
337 scanned += info.RegionSize;
341 return ::VirtualAlloc(nullptr,
343 MEM_RESERVE | MEM_COMMIT,
344 PAGE_EXECUTE_READWRITE);
348 // Used by unittests to release mapped memory space.
349 void TestOnlyReleaseTrampolineRegions() {
350 for (size_t bucket = 0; bucket < kMaxTrampolineRegion; ++bucket) {
351 TrampolineMemoryRegion *current = &TrampolineRegions[bucket];
352 if (current->content == 0)
354 ::VirtualFree((void*)current->content, 0, MEM_RELEASE);
355 current->content = 0;
359 static uptr AllocateMemoryForTrampoline(uptr image_address, size_t size) {
360 // Find a region within 2G with enough space to allocate |size| bytes.
361 TrampolineMemoryRegion *region = nullptr;
362 for (size_t bucket = 0; bucket < kMaxTrampolineRegion; ++bucket) {
363 TrampolineMemoryRegion* current = &TrampolineRegions[bucket];
364 if (current->content == 0) {
365 // No valid region found, allocate a new region.
366 size_t bucket_size = GetMmapGranularity();
367 void *content = AllocateTrampolineRegion(image_address, bucket_size);
368 if (content == nullptr)
371 current->content = (uptr)content;
372 current->allocated_size = 0;
373 current->max_size = bucket_size;
376 } else if (current->max_size - current->allocated_size > size) {
377 #if SANITIZER_WINDOWS64
378 // In 64-bits, the memory space must be allocated within 2G boundary.
379 uptr next_address = current->content + current->allocated_size;
380 if (next_address < image_address ||
381 next_address - image_address >= 0x7FFF0000)
384 // The space can be allocated in the current region.
390 // Failed to find a region.
391 if (region == nullptr)
394 // Allocate the space in the current region.
395 uptr allocated_space = region->content + region->allocated_size;
396 region->allocated_size += size;
397 WritePadding(allocated_space, size);
399 return allocated_space;
402 // Returns 0 on error.
403 static size_t GetInstructionSize(uptr address, size_t* rel_offset = nullptr) {
404 switch (*(u64*)address) {
405 case 0x90909090909006EB: // stub: jmp over 6 x nop.
409 switch (*(u8*)address) {
410 case 0x90: // 90 : nop
413 case 0x50: // push eax / rax
414 case 0x51: // push ecx / rcx
415 case 0x52: // push edx / rdx
416 case 0x53: // push ebx / rbx
417 case 0x54: // push esp / rsp
418 case 0x55: // push ebp / rbp
419 case 0x56: // push esi / rsi
420 case 0x57: // push edi / rdi
421 case 0x5D: // pop ebp / rbp
424 case 0x6A: // 6A XX = push XX
427 case 0xb8: // b8 XX XX XX XX : mov eax, XX XX XX XX
428 case 0xB9: // b9 XX XX XX XX : mov ecx, XX XX XX XX
431 // Cannot overwrite control-instruction. Return 0 to indicate failure.
432 case 0xE9: // E9 XX XX XX XX : jmp <label>
433 case 0xE8: // E8 XX XX XX XX : call <func>
434 case 0xC3: // C3 : ret
435 case 0xEB: // EB XX : jmp XX (short jump)
436 case 0x70: // 7Y YY : jy XX (short conditional jump)
455 switch (*(u16*)(address)) {
456 case 0xFF8B: // 8B FF : mov edi, edi
457 case 0xEC8B: // 8B EC : mov ebp, esp
458 case 0xc889: // 89 C8 : mov eax, ecx
459 case 0xC18B: // 8B C1 : mov eax, ecx
460 case 0xC033: // 33 C0 : xor eax, eax
461 case 0xC933: // 33 C9 : xor ecx, ecx
462 case 0xD233: // 33 D2 : xor edx, edx
465 // Cannot overwrite control-instruction. Return 0 to indicate failure.
466 case 0x25FF: // FF 25 XX XX XX XX : jmp [XXXXXXXX]
470 switch (0x00FFFFFF & *(u32*)address) {
471 case 0x24A48D: // 8D A4 24 XX XX XX XX : lea esp, [esp + XX XX XX XX]
475 #if SANITIZER_WINDOWS64
476 switch (*(u8*)address) {
477 case 0xA1: // A1 XX XX XX XX XX XX XX XX :
478 // movabs eax, dword ptr ds:[XXXXXXXX]
482 switch (*(u16*)address) {
483 case 0x5040: // push rax
484 case 0x5140: // push rcx
485 case 0x5240: // push rdx
486 case 0x5340: // push rbx
487 case 0x5440: // push rsp
488 case 0x5540: // push rbp
489 case 0x5640: // push rsi
490 case 0x5740: // push rdi
491 case 0x5441: // push r12
492 case 0x5541: // push r13
493 case 0x5641: // push r14
494 case 0x5741: // push r15
495 case 0x9066: // Two-byte NOP
498 case 0x058B: // 8B 05 XX XX XX XX : mov eax, dword ptr [XX XX XX XX]
504 switch (0x00FFFFFF & *(u32*)address) {
505 case 0xe58948: // 48 8b c4 : mov rbp, rsp
506 case 0xc18b48: // 48 8b c1 : mov rax, rcx
507 case 0xc48b48: // 48 8b c4 : mov rax, rsp
508 case 0xd9f748: // 48 f7 d9 : neg rcx
509 case 0xd12b48: // 48 2b d1 : sub rdx, rcx
510 case 0x07c1f6: // f6 c1 07 : test cl, 0x7
511 case 0xc98548: // 48 85 C9 : test rcx, rcx
512 case 0xc0854d: // 4d 85 c0 : test r8, r8
513 case 0xc2b60f: // 0f b6 c2 : movzx eax, dl
514 case 0xc03345: // 45 33 c0 : xor r8d, r8d
515 case 0xdb3345: // 45 33 DB : xor r11d, r11d
516 case 0xd98b4c: // 4c 8b d9 : mov r11, rcx
517 case 0xd28b4c: // 4c 8b d2 : mov r10, rdx
518 case 0xc98b4c: // 4C 8B C9 : mov r9, rcx
519 case 0xd2b60f: // 0f b6 d2 : movzx edx, dl
520 case 0xca2b48: // 48 2b ca : sub rcx, rdx
521 case 0x10b70f: // 0f b7 10 : movzx edx, WORD PTR [rax]
522 case 0xc00b4d: // 3d 0b c0 : or r8, r8
523 case 0xd18b48: // 48 8b d1 : mov rdx, rcx
524 case 0xdc8b4c: // 4c 8b dc : mov r11, rsp
525 case 0xd18b4c: // 4c 8b d1 : mov r10, rcx
528 case 0xec8348: // 48 83 ec XX : sub rsp, XX
529 case 0xf88349: // 49 83 f8 XX : cmp r8, XX
530 case 0x588948: // 48 89 58 XX : mov QWORD PTR[rax + XX], rbx
533 case 0xec8148: // 48 81 EC XX XX XX XX : sub rsp, XXXXXXXX
536 case 0x058b48: // 48 8b 05 XX XX XX XX :
537 // mov rax, QWORD PTR [rip + XXXXXXXX]
538 case 0x25ff48: // 48 ff 25 XX XX XX XX :
539 // rex.W jmp QWORD PTR [rip + XXXXXXXX]
541 // Instructions having offset relative to 'rip' need offset adjustment.
546 case 0x2444c7: // C7 44 24 XX YY YY YY YY
547 // mov dword ptr [rsp + XX], YYYYYYYY
551 switch (*(u32*)(address)) {
552 case 0x24448b48: // 48 8b 44 24 XX : mov rax, QWORD ptr [rsp + XX]
553 case 0x246c8948: // 48 89 6C 24 XX : mov QWORD ptr [rsp + XX], rbp
554 case 0x245c8948: // 48 89 5c 24 XX : mov QWORD PTR [rsp + XX], rbx
555 case 0x24748948: // 48 89 74 24 XX : mov QWORD PTR [rsp + XX], rsi
556 case 0x244C8948: // 48 89 4C 24 XX : mov QWORD PTR [rsp + XX], rcx
558 case 0x24648348: // 48 83 64 24 XX : and QWORD PTR [rsp + XX], YY
564 switch (*(u8*)address) {
565 case 0xA1: // A1 XX XX XX XX : mov eax, dword ptr ds:[XXXXXXXX]
568 switch (*(u16*)address) {
569 case 0x458B: // 8B 45 XX : mov eax, dword ptr [ebp + XX]
570 case 0x5D8B: // 8B 5D XX : mov ebx, dword ptr [ebp + XX]
571 case 0x7D8B: // 8B 7D XX : mov edi, dword ptr [ebp + XX]
572 case 0xEC83: // 83 EC XX : sub esp, XX
573 case 0x75FF: // FF 75 XX : push dword ptr [ebp + XX]
575 case 0xC1F7: // F7 C1 XX YY ZZ WW : test ecx, WWZZYYXX
576 case 0x25FF: // FF 25 XX YY ZZ WW : jmp dword ptr ds:[WWZZYYXX]
578 case 0x3D83: // 83 3D XX YY ZZ WW TT : cmp TT, WWZZYYXX
580 case 0x7D83: // 83 7D XX YY : cmp dword ptr [ebp + XX], YY
584 switch (0x00FFFFFF & *(u32*)address) {
585 case 0x24448A: // 8A 44 24 XX : mov eal, dword ptr [esp + XX]
586 case 0x24448B: // 8B 44 24 XX : mov eax, dword ptr [esp + XX]
587 case 0x244C8B: // 8B 4C 24 XX : mov ecx, dword ptr [esp + XX]
588 case 0x24548B: // 8B 54 24 XX : mov edx, dword ptr [esp + XX]
589 case 0x24748B: // 8B 74 24 XX : mov esi, dword ptr [esp + XX]
590 case 0x247C8B: // 8B 7C 24 XX : mov edi, dword ptr [esp + XX]
594 switch (*(u32*)address) {
595 case 0x2444B60F: // 0F B6 44 24 XX : movzx eax, byte ptr [esp + XX]
600 // Unknown instruction!
601 // FIXME: Unknown instruction failures might happen when we add a new
602 // interceptor or a new compiler version. In either case, they should result
603 // in visible and readable error messages. However, merely calling abort()
604 // leads to an infinite recursion in CheckFailed.
605 InterceptionFailed();
609 // Returns 0 on error.
610 static size_t RoundUpToInstrBoundary(size_t size, uptr address) {
612 while (cursor < size) {
613 size_t instruction_size = GetInstructionSize(address + cursor);
614 if (!instruction_size)
616 cursor += instruction_size;
621 static bool CopyInstructions(uptr to, uptr from, size_t size) {
623 while (cursor != size) {
624 size_t rel_offset = 0;
625 size_t instruction_size = GetInstructionSize(from + cursor, &rel_offset);
626 _memcpy((void*)(to + cursor), (void*)(from + cursor),
627 (size_t)instruction_size);
629 uptr delta = to - from;
630 uptr relocated_offset = *(u32*)(to + cursor + rel_offset) - delta;
631 #if SANITIZER_WINDOWS64
632 if (relocated_offset + 0x80000000U >= 0xFFFFFFFFU)
635 *(u32*)(to + cursor + rel_offset) = relocated_offset;
637 cursor += instruction_size;
643 #if !SANITIZER_WINDOWS64
644 bool OverrideFunctionWithDetour(
645 uptr old_func, uptr new_func, uptr *orig_old_func) {
646 const int kDetourHeaderLen = 5;
647 const u16 kDetourInstruction = 0xFF8B;
649 uptr header = (uptr)old_func - kDetourHeaderLen;
650 uptr patch_length = kDetourHeaderLen + kShortJumpInstructionLength;
652 // Validate that the function is hookable.
653 if (*(u16*)old_func != kDetourInstruction ||
654 !IsMemoryPadding(header, kDetourHeaderLen))
657 // Change memory protection to writable.
658 DWORD protection = 0;
659 if (!ChangeMemoryProtection(header, patch_length, &protection))
662 // Write a relative jump to the redirected function.
663 WriteJumpInstruction(header, new_func);
665 // Write the short jump to the function prefix.
666 WriteShortJumpInstruction(old_func, header);
668 // Restore previous memory protection.
669 if (!RestoreMemoryProtection(header, patch_length, protection))
673 *orig_old_func = old_func + kShortJumpInstructionLength;
679 bool OverrideFunctionWithRedirectJump(
680 uptr old_func, uptr new_func, uptr *orig_old_func) {
681 // Check whether the first instruction is a relative jump.
682 if (*(u8*)old_func != 0xE9)
686 uptr relative_offset = *(u32*)(old_func + 1);
687 uptr absolute_target = old_func + relative_offset + kJumpInstructionLength;
688 *orig_old_func = absolute_target;
691 #if SANITIZER_WINDOWS64
692 // If needed, get memory space for a trampoline jump.
693 uptr trampoline = AllocateMemoryForTrampoline(old_func, kDirectBranchLength);
696 WriteDirectBranch(trampoline, new_func);
699 // Change memory protection to writable.
700 DWORD protection = 0;
701 if (!ChangeMemoryProtection(old_func, kJumpInstructionLength, &protection))
704 // Write a relative jump to the redirected function.
705 WriteJumpInstruction(old_func, FIRST_32_SECOND_64(new_func, trampoline));
707 // Restore previous memory protection.
708 if (!RestoreMemoryProtection(old_func, kJumpInstructionLength, protection))
714 bool OverrideFunctionWithHotPatch(
715 uptr old_func, uptr new_func, uptr *orig_old_func) {
716 const int kHotPatchHeaderLen = kBranchLength;
718 uptr header = (uptr)old_func - kHotPatchHeaderLen;
719 uptr patch_length = kHotPatchHeaderLen + kShortJumpInstructionLength;
721 // Validate that the function is hot patchable.
722 size_t instruction_size = GetInstructionSize(old_func);
723 if (instruction_size < kShortJumpInstructionLength ||
724 !FunctionHasPadding(old_func, kHotPatchHeaderLen))
728 // Put the needed instructions into the trampoline bytes.
729 uptr trampoline_length = instruction_size + kDirectBranchLength;
730 uptr trampoline = AllocateMemoryForTrampoline(old_func, trampoline_length);
733 if (!CopyInstructions(trampoline, old_func, instruction_size))
735 WriteDirectBranch(trampoline + instruction_size,
736 old_func + instruction_size);
737 *orig_old_func = trampoline;
740 // If needed, get memory space for indirect address.
741 uptr indirect_address = 0;
742 #if SANITIZER_WINDOWS64
743 indirect_address = AllocateMemoryForTrampoline(old_func, kAddressLength);
744 if (!indirect_address)
748 // Change memory protection to writable.
749 DWORD protection = 0;
750 if (!ChangeMemoryProtection(header, patch_length, &protection))
753 // Write jumps to the redirected function.
754 WriteBranch(header, indirect_address, new_func);
755 WriteShortJumpInstruction(old_func, header);
757 // Restore previous memory protection.
758 if (!RestoreMemoryProtection(header, patch_length, protection))
764 bool OverrideFunctionWithTrampoline(
765 uptr old_func, uptr new_func, uptr *orig_old_func) {
767 size_t instructions_length = kBranchLength;
768 size_t padding_length = 0;
769 uptr indirect_address = 0;
772 // Find out the number of bytes of the instructions we need to copy
773 // to the trampoline.
774 instructions_length = RoundUpToInstrBoundary(kBranchLength, old_func);
775 if (!instructions_length)
778 // Put the needed instructions into the trampoline bytes.
779 uptr trampoline_length = instructions_length + kDirectBranchLength;
780 uptr trampoline = AllocateMemoryForTrampoline(old_func, trampoline_length);
783 if (!CopyInstructions(trampoline, old_func, instructions_length))
785 WriteDirectBranch(trampoline + instructions_length,
786 old_func + instructions_length);
787 *orig_old_func = trampoline;
790 #if SANITIZER_WINDOWS64
791 // Check if the targeted address can be encoded in the function padding.
792 // Otherwise, allocate it in the trampoline region.
793 if (IsMemoryPadding(old_func - kAddressLength, kAddressLength)) {
794 indirect_address = old_func - kAddressLength;
795 padding_length = kAddressLength;
797 indirect_address = AllocateMemoryForTrampoline(old_func, kAddressLength);
798 if (!indirect_address)
803 // Change memory protection to writable.
804 uptr patch_address = old_func - padding_length;
805 uptr patch_length = instructions_length + padding_length;
806 DWORD protection = 0;
807 if (!ChangeMemoryProtection(patch_address, patch_length, &protection))
810 // Patch the original function.
811 WriteBranch(old_func, indirect_address, new_func);
813 // Restore previous memory protection.
814 if (!RestoreMemoryProtection(patch_address, patch_length, protection))
820 bool OverrideFunction(
821 uptr old_func, uptr new_func, uptr *orig_old_func) {
822 #if !SANITIZER_WINDOWS64
823 if (OverrideFunctionWithDetour(old_func, new_func, orig_old_func))
826 if (OverrideFunctionWithRedirectJump(old_func, new_func, orig_old_func))
828 if (OverrideFunctionWithHotPatch(old_func, new_func, orig_old_func))
830 if (OverrideFunctionWithTrampoline(old_func, new_func, orig_old_func))
835 static void **InterestingDLLsAvailable() {
836 static const char *InterestingDLLs[] = {
838 "msvcr100.dll", // VS2010
839 "msvcr110.dll", // VS2012
840 "msvcr120.dll", // VS2013
841 "vcruntime140.dll", // VS2015
842 "ucrtbase.dll", // Universal CRT
843 // NTDLL should go last as it exports some functions that we should
844 // override in the CRT [presumably only used internally].
846 static void *result[ARRAY_SIZE(InterestingDLLs)] = { 0 };
848 for (size_t i = 0, j = 0; InterestingDLLs[i]; ++i) {
849 if (HMODULE h = GetModuleHandleA(InterestingDLLs[i]))
850 result[j++] = (void *)h;
857 // Utility for reading loaded PE images.
858 template <typename T> class RVAPtr {
860 RVAPtr(void *module, uptr rva)
861 : ptr_(reinterpret_cast<T *>(reinterpret_cast<char *>(module) + rva)) {}
862 operator T *() { return ptr_; }
863 T *operator->() { return ptr_; }
864 T *operator++() { return ++ptr_; }
871 // Internal implementation of GetProcAddress. At least since Windows 8,
872 // GetProcAddress appears to initialize DLLs before returning function pointers
873 // into them. This is problematic for the sanitizers, because they typically
874 // want to intercept malloc *before* MSVCRT initializes. Our internal
875 // implementation walks the export list manually without doing initialization.
876 uptr InternalGetProcAddress(void *module, const char *func_name) {
877 // Check that the module header is full and present.
878 RVAPtr<IMAGE_DOS_HEADER> dos_stub(module, 0);
879 RVAPtr<IMAGE_NT_HEADERS> headers(module, dos_stub->e_lfanew);
880 if (!module || dos_stub->e_magic != IMAGE_DOS_SIGNATURE || // "MZ"
881 headers->Signature != IMAGE_NT_SIGNATURE || // "PE\0\0"
882 headers->FileHeader.SizeOfOptionalHeader <
883 sizeof(IMAGE_OPTIONAL_HEADER)) {
887 IMAGE_DATA_DIRECTORY *export_directory =
888 &headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT];
889 if (export_directory->Size == 0)
891 RVAPtr<IMAGE_EXPORT_DIRECTORY> exports(module,
892 export_directory->VirtualAddress);
893 RVAPtr<DWORD> functions(module, exports->AddressOfFunctions);
894 RVAPtr<DWORD> names(module, exports->AddressOfNames);
895 RVAPtr<WORD> ordinals(module, exports->AddressOfNameOrdinals);
897 for (DWORD i = 0; i < exports->NumberOfNames; i++) {
898 RVAPtr<char> name(module, names[i]);
899 if (!strcmp(func_name, name)) {
900 DWORD index = ordinals[i];
901 RVAPtr<char> func(module, functions[index]);
903 // Handle forwarded functions.
904 DWORD offset = functions[index];
905 if (offset >= export_directory->VirtualAddress &&
906 offset < export_directory->VirtualAddress + export_directory->Size) {
907 // An entry for a forwarded function is a string with the following
908 // format: "<module> . <function_name>" that is stored into the
909 // exported directory.
910 char function_name[256];
911 size_t funtion_name_length = _strlen(func);
912 if (funtion_name_length >= sizeof(function_name) - 1)
913 InterceptionFailed();
915 _memcpy(function_name, func, funtion_name_length);
916 function_name[funtion_name_length] = '\0';
917 char* separator = _strchr(function_name, '.');
919 InterceptionFailed();
922 void* redirected_module = GetModuleHandleA(function_name);
923 if (!redirected_module)
924 InterceptionFailed();
925 return InternalGetProcAddress(redirected_module, separator + 1);
928 return (uptr)(char *)func;
935 bool OverrideFunction(
936 const char *func_name, uptr new_func, uptr *orig_old_func) {
938 void **DLLs = InterestingDLLsAvailable();
939 for (size_t i = 0; DLLs[i]; ++i) {
940 uptr func_addr = InternalGetProcAddress(DLLs[i], func_name);
942 OverrideFunction(func_addr, new_func, orig_old_func)) {
949 bool OverrideImportedFunction(const char *module_to_patch,
950 const char *imported_module,
951 const char *function_name, uptr new_function,
952 uptr *orig_old_func) {
953 HMODULE module = GetModuleHandleA(module_to_patch);
957 // Check that the module header is full and present.
958 RVAPtr<IMAGE_DOS_HEADER> dos_stub(module, 0);
959 RVAPtr<IMAGE_NT_HEADERS> headers(module, dos_stub->e_lfanew);
960 if (!module || dos_stub->e_magic != IMAGE_DOS_SIGNATURE || // "MZ"
961 headers->Signature != IMAGE_NT_SIGNATURE || // "PE\0\0"
962 headers->FileHeader.SizeOfOptionalHeader <
963 sizeof(IMAGE_OPTIONAL_HEADER)) {
967 IMAGE_DATA_DIRECTORY *import_directory =
968 &headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT];
970 // Iterate the list of imported DLLs. FirstThunk will be null for the last
972 RVAPtr<IMAGE_IMPORT_DESCRIPTOR> imports(module,
973 import_directory->VirtualAddress);
974 for (; imports->FirstThunk != 0; ++imports) {
975 RVAPtr<const char> modname(module, imports->Name);
976 if (_stricmp(&*modname, imported_module) == 0)
979 if (imports->FirstThunk == 0)
982 // We have two parallel arrays: the import address table (IAT) and the table
983 // of names. They start out containing the same data, but the loader rewrites
984 // the IAT to hold imported addresses and leaves the name table in
985 // OriginalFirstThunk alone.
986 RVAPtr<IMAGE_THUNK_DATA> name_table(module, imports->OriginalFirstThunk);
987 RVAPtr<IMAGE_THUNK_DATA> iat(module, imports->FirstThunk);
988 for (; name_table->u1.Ordinal != 0; ++name_table, ++iat) {
989 if (!IMAGE_SNAP_BY_ORDINAL(name_table->u1.Ordinal)) {
990 RVAPtr<IMAGE_IMPORT_BY_NAME> import_by_name(
991 module, name_table->u1.ForwarderString);
992 const char *funcname = &import_by_name->Name[0];
993 if (strcmp(funcname, function_name) == 0)
997 if (name_table->u1.Ordinal == 0)
1000 // Now we have the correct IAT entry. Do the swap. We have to make the page
1001 // read/write first.
1003 *orig_old_func = iat->u1.AddressOfData;
1004 DWORD old_prot, unused_prot;
1005 if (!VirtualProtect(&iat->u1.AddressOfData, 4, PAGE_EXECUTE_READWRITE,
1008 iat->u1.AddressOfData = new_function;
1009 if (!VirtualProtect(&iat->u1.AddressOfData, 4, old_prot, &unused_prot))
1010 return false; // Not clear if this failure bothers us.
1014 } // namespace __interception
1016 #endif // SANITIZER_MAC