1 //===-- interception_linux.cc -----------------------------------*- C++ -*-===//
3 // This file is distributed under the University of Illinois Open Source
4 // License. See LICENSE.TXT for details.
6 //===----------------------------------------------------------------------===//
8 // This file is a part of AddressSanitizer, an address sanity checker.
10 // Windows-specific interception methods.
12 // This file is implementing several hooking techniques to intercept calls
13 // to functions. The hooks are dynamically installed by modifying the assembly
16 // The hooking techniques are making assumptions on the way the code is
17 // generated and are safe under these assumptions.
19 // On 64-bit architecture, there is no direct 64-bit jump instruction. To allow
20 // arbitrary branching on the whole memory space, the notion of trampoline
21 // region is used. A trampoline region is a memory space withing 2G boundary
22 // where it is safe to add custom assembly code to build 64-bit jumps.
29 // The Detour hooking technique is assuming the presence of an header with
30 // padding and an overridable 2-bytes nop instruction (mov edi, edi). The
31 // nop instruction can safely be replaced by a 2-bytes jump without any need
32 // to save the instruction. A jump to the target is encoded in the function
33 // header and the nop instruction is replaced by a short jump to the header.
35 // head: 5 x nop head: jmp <hook>
36 // func: mov edi, edi --> func: jmp short <head>
39 // This technique is only implemented on 32-bit architecture.
40 // Most of the time, Windows API are hookable with the detour technique.
44 // The redirect jump is applicable when the first instruction is a direct
45 // jump. The instruction is replaced by jump to the hook.
47 // func: jmp <label> --> func: jmp <hook>
49 // On an 64-bit architecture, a trampoline is inserted.
51 // func: jmp <label> --> func: jmp <tramp>
55 // tramp: jmp QWORD [addr]
56 // addr: .bytes <hook>
58 // Note: <real> is equilavent to <label>.
62 // The HotPatch hooking is assuming the presence of an header with padding
63 // and a first instruction with at least 2-bytes.
65 // The reason to enforce the 2-bytes limitation is to provide the minimal
66 // space to encode a short jump. HotPatch technique is only rewriting one
67 // instruction to avoid breaking a sequence of instructions containing a
70 // Assumptions are enforced by MSVC compiler by using the /HOTPATCH flag.
71 // see: https://msdn.microsoft.com/en-us/library/ms173507.aspx
72 // Default padding length is 5 bytes in 32-bits and 6 bytes in 64-bits.
74 // head: 5 x nop head: jmp <hook>
75 // func: <instr> --> func: jmp short <head>
82 // On an 64-bit architecture:
84 // head: 6 x nop head: jmp QWORD [addr1]
85 // func: <instr> --> func: jmp short <head>
89 // addr1: .bytes <hook>
92 // addr2: .bytes <body>
96 // The Trampoline hooking technique is the most aggressive one. It is
97 // assuming that there is a sequence of instructions that can be safely
98 // replaced by a jump (enough room and no incoming branches).
100 // Unfortunately, these assumptions can't be safely presumed and code may
101 // be broken after hooking.
103 // func: <instr> --> func: jmp <hook>
112 // On an 64-bit architecture:
114 // func: <instr> --> func: jmp QWORD [addr1]
119 // addr1: .bytes <hook>
123 // addr2: .bytes <body>
124 //===----------------------------------------------------------------------===//
128 #include "interception.h"
129 #include "sanitizer_common/sanitizer_platform.h"
130 #define WIN32_LEAN_AND_MEAN
133 namespace __interception
{
135 static const int kAddressLength
= FIRST_32_SECOND_64(4, 8);
136 static const int kJumpInstructionLength
= 5;
137 static const int kShortJumpInstructionLength
= 2;
138 static const int kIndirectJumpInstructionLength
= 6;
139 static const int kBranchLength
=
140 FIRST_32_SECOND_64(kJumpInstructionLength
, kIndirectJumpInstructionLength
);
141 static const int kDirectBranchLength
= kBranchLength
+ kAddressLength
;
143 static void InterceptionFailed() {
144 // Do we have a good way to abort with an error message here?
148 static bool DistanceIsWithin2Gig(uptr from
, uptr target
) {
149 #if SANITIZER_WINDOWS64
151 return target
- from
<= (uptr
)0x7FFFFFFFU
;
153 return from
- target
<= (uptr
)0x80000000U
;
155 // In a 32-bit address space, the address calculation will wrap, so this check
161 static uptr
GetMmapGranularity() {
164 return si
.dwAllocationGranularity
;
167 static uptr
RoundUpTo(uptr size
, uptr boundary
) {
168 return (size
+ boundary
- 1) & ~(boundary
- 1);
171 // FIXME: internal_str* and internal_mem* functions should be moved from the
172 // ASan sources into interception/.
174 static size_t _strlen(const char *str
) {
176 while (*p
!= '\0') ++p
;
180 static char* _strchr(char* str
, char c
) {
189 static void _memset(void *p
, int value
, size_t sz
) {
190 for (size_t i
= 0; i
< sz
; ++i
)
191 ((char*)p
)[i
] = (char)value
;
194 static void _memcpy(void *dst
, void *src
, size_t sz
) {
195 char *dst_c
= (char*)dst
,
197 for (size_t i
= 0; i
< sz
; ++i
)
201 static bool ChangeMemoryProtection(
202 uptr address
, uptr size
, DWORD
*old_protection
) {
203 return ::VirtualProtect((void*)address
, size
,
204 PAGE_EXECUTE_READWRITE
,
205 old_protection
) != FALSE
;
208 static bool RestoreMemoryProtection(
209 uptr address
, uptr size
, DWORD old_protection
) {
211 return ::VirtualProtect((void*)address
, size
,
216 static bool IsMemoryPadding(uptr address
, uptr size
) {
217 u8
* function
= (u8
*)address
;
218 for (size_t i
= 0; i
< size
; ++i
)
219 if (function
[i
] != 0x90 && function
[i
] != 0xCC)
224 static const u8 kHintNop9Bytes
[] = {
225 0x66, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00
229 static bool FunctionHasPrefix(uptr address
, const T
&pattern
) {
230 u8
* function
= (u8
*)address
- sizeof(pattern
);
231 for (size_t i
= 0; i
< sizeof(pattern
); ++i
)
232 if (function
[i
] != pattern
[i
])
237 static bool FunctionHasPadding(uptr address
, uptr size
) {
238 if (IsMemoryPadding(address
- size
, size
))
240 if (size
<= sizeof(kHintNop9Bytes
) &&
241 FunctionHasPrefix(address
, kHintNop9Bytes
))
246 static void WritePadding(uptr from
, uptr size
) {
247 _memset((void*)from
, 0xCC, (size_t)size
);
250 static void WriteJumpInstruction(uptr from
, uptr target
) {
251 if (!DistanceIsWithin2Gig(from
+ kJumpInstructionLength
, target
))
252 InterceptionFailed();
253 ptrdiff_t offset
= target
- from
- kJumpInstructionLength
;
255 *(u32
*)(from
+ 1) = offset
;
258 static void WriteShortJumpInstruction(uptr from
, uptr target
) {
259 sptr offset
= target
- from
- kShortJumpInstructionLength
;
260 if (offset
< -128 || offset
> 127)
261 InterceptionFailed();
263 *(u8
*)(from
+ 1) = (u8
)offset
;
266 #if SANITIZER_WINDOWS64
267 static void WriteIndirectJumpInstruction(uptr from
, uptr indirect_target
) {
268 // jmp [rip + <offset>] = FF 25 <offset> where <offset> is a relative
270 // The offset is the distance from then end of the jump instruction to the
271 // memory location containing the targeted address. The displacement is still
272 // 32-bit in x64, so indirect_target must be located within +/- 2GB range.
273 int offset
= indirect_target
- from
- kIndirectJumpInstructionLength
;
274 if (!DistanceIsWithin2Gig(from
+ kIndirectJumpInstructionLength
,
276 InterceptionFailed();
278 *(u16
*)from
= 0x25FF;
279 *(u32
*)(from
+ 2) = offset
;
283 static void WriteBranch(
284 uptr from
, uptr indirect_target
, uptr target
) {
285 #if SANITIZER_WINDOWS64
286 WriteIndirectJumpInstruction(from
, indirect_target
);
287 *(u64
*)indirect_target
= target
;
289 (void)indirect_target
;
290 WriteJumpInstruction(from
, target
);
294 static void WriteDirectBranch(uptr from
, uptr target
) {
295 #if SANITIZER_WINDOWS64
296 // Emit an indirect jump through immediately following bytes:
297 // jmp [rip + kBranchLength]
299 WriteBranch(from
, from
+ kBranchLength
, target
);
301 WriteJumpInstruction(from
, target
);
305 struct TrampolineMemoryRegion
{
311 static const uptr kTrampolineScanLimitRange
= 1 << 31; // 2 gig
312 static const int kMaxTrampolineRegion
= 1024;
313 static TrampolineMemoryRegion TrampolineRegions
[kMaxTrampolineRegion
];
315 static void *AllocateTrampolineRegion(uptr image_address
, size_t granularity
) {
316 #if SANITIZER_WINDOWS64
317 uptr address
= image_address
;
319 while (scanned
< kTrampolineScanLimitRange
) {
320 MEMORY_BASIC_INFORMATION info
;
321 if (!::VirtualQuery((void*)address
, &info
, sizeof(info
)))
324 // Check whether a region can be allocated at |address|.
325 if (info
.State
== MEM_FREE
&& info
.RegionSize
>= granularity
) {
326 void *page
= ::VirtualAlloc((void*)RoundUpTo(address
, granularity
),
328 MEM_RESERVE
| MEM_COMMIT
,
329 PAGE_EXECUTE_READWRITE
);
333 // Move to the next region.
334 address
= (uptr
)info
.BaseAddress
+ info
.RegionSize
;
335 scanned
+= info
.RegionSize
;
339 return ::VirtualAlloc(nullptr,
341 MEM_RESERVE
| MEM_COMMIT
,
342 PAGE_EXECUTE_READWRITE
);
346 // Used by unittests to release mapped memory space.
347 void TestOnlyReleaseTrampolineRegions() {
348 for (size_t bucket
= 0; bucket
< kMaxTrampolineRegion
; ++bucket
) {
349 TrampolineMemoryRegion
*current
= &TrampolineRegions
[bucket
];
350 if (current
->content
== 0)
352 ::VirtualFree((void*)current
->content
, 0, MEM_RELEASE
);
353 current
->content
= 0;
357 static uptr
AllocateMemoryForTrampoline(uptr image_address
, size_t size
) {
358 // Find a region within 2G with enough space to allocate |size| bytes.
359 TrampolineMemoryRegion
*region
= nullptr;
360 for (size_t bucket
= 0; bucket
< kMaxTrampolineRegion
; ++bucket
) {
361 TrampolineMemoryRegion
* current
= &TrampolineRegions
[bucket
];
362 if (current
->content
== 0) {
363 // No valid region found, allocate a new region.
364 size_t bucket_size
= GetMmapGranularity();
365 void *content
= AllocateTrampolineRegion(image_address
, bucket_size
);
366 if (content
== nullptr)
369 current
->content
= (uptr
)content
;
370 current
->allocated_size
= 0;
371 current
->max_size
= bucket_size
;
374 } else if (current
->max_size
- current
->allocated_size
> size
) {
375 #if SANITIZER_WINDOWS64
376 // In 64-bits, the memory space must be allocated within 2G boundary.
377 uptr next_address
= current
->content
+ current
->allocated_size
;
378 if (next_address
< image_address
||
379 next_address
- image_address
>= 0x7FFF0000)
382 // The space can be allocated in the current region.
388 // Failed to find a region.
389 if (region
== nullptr)
392 // Allocate the space in the current region.
393 uptr allocated_space
= region
->content
+ region
->allocated_size
;
394 region
->allocated_size
+= size
;
395 WritePadding(allocated_space
, size
);
397 return allocated_space
;
400 // Returns 0 on error.
401 static size_t GetInstructionSize(uptr address
, size_t* rel_offset
= nullptr) {
402 switch (*(u64
*)address
) {
403 case 0x90909090909006EB: // stub: jmp over 6 x nop.
407 switch (*(u8
*)address
) {
408 case 0x90: // 90 : nop
411 case 0x50: // push eax / rax
412 case 0x51: // push ecx / rcx
413 case 0x52: // push edx / rdx
414 case 0x53: // push ebx / rbx
415 case 0x54: // push esp / rsp
416 case 0x55: // push ebp / rbp
417 case 0x56: // push esi / rsi
418 case 0x57: // push edi / rdi
419 case 0x5D: // pop ebp / rbp
422 case 0x6A: // 6A XX = push XX
425 case 0xb8: // b8 XX XX XX XX : mov eax, XX XX XX XX
426 case 0xB9: // b9 XX XX XX XX : mov ecx, XX XX XX XX
429 // Cannot overwrite control-instruction. Return 0 to indicate failure.
430 case 0xE9: // E9 XX XX XX XX : jmp <label>
431 case 0xE8: // E8 XX XX XX XX : call <func>
432 case 0xC3: // C3 : ret
433 case 0xEB: // EB XX : jmp XX (short jump)
434 case 0x70: // 7Y YY : jy XX (short conditional jump)
453 switch (*(u16
*)(address
)) {
454 case 0xFF8B: // 8B FF : mov edi, edi
455 case 0xEC8B: // 8B EC : mov ebp, esp
456 case 0xc889: // 89 C8 : mov eax, ecx
457 case 0xC18B: // 8B C1 : mov eax, ecx
458 case 0xC033: // 33 C0 : xor eax, eax
459 case 0xC933: // 33 C9 : xor ecx, ecx
460 case 0xD233: // 33 D2 : xor edx, edx
463 // Cannot overwrite control-instruction. Return 0 to indicate failure.
464 case 0x25FF: // FF 25 XX XX XX XX : jmp [XXXXXXXX]
468 switch (0x00FFFFFF & *(u32
*)address
) {
469 case 0x24A48D: // 8D A4 24 XX XX XX XX : lea esp, [esp + XX XX XX XX]
473 #if SANITIZER_WINDOWS64
474 switch (*(u8
*)address
) {
475 case 0xA1: // A1 XX XX XX XX XX XX XX XX :
476 // movabs eax, dword ptr ds:[XXXXXXXX]
480 switch (*(u16
*)address
) {
481 case 0x5040: // push rax
482 case 0x5140: // push rcx
483 case 0x5240: // push rdx
484 case 0x5340: // push rbx
485 case 0x5440: // push rsp
486 case 0x5540: // push rbp
487 case 0x5640: // push rsi
488 case 0x5740: // push rdi
489 case 0x5441: // push r12
490 case 0x5541: // push r13
491 case 0x5641: // push r14
492 case 0x5741: // push r15
493 case 0x9066: // Two-byte NOP
496 case 0x058B: // 8B 05 XX XX XX XX : mov eax, dword ptr [XX XX XX XX]
502 switch (0x00FFFFFF & *(u32
*)address
) {
503 case 0xe58948: // 48 8b c4 : mov rbp, rsp
504 case 0xc18b48: // 48 8b c1 : mov rax, rcx
505 case 0xc48b48: // 48 8b c4 : mov rax, rsp
506 case 0xd9f748: // 48 f7 d9 : neg rcx
507 case 0xd12b48: // 48 2b d1 : sub rdx, rcx
508 case 0x07c1f6: // f6 c1 07 : test cl, 0x7
509 case 0xc98548: // 48 85 C9 : test rcx, rcx
510 case 0xc0854d: // 4d 85 c0 : test r8, r8
511 case 0xc2b60f: // 0f b6 c2 : movzx eax, dl
512 case 0xc03345: // 45 33 c0 : xor r8d, r8d
513 case 0xdb3345: // 45 33 DB : xor r11d, r11d
514 case 0xd98b4c: // 4c 8b d9 : mov r11, rcx
515 case 0xd28b4c: // 4c 8b d2 : mov r10, rdx
516 case 0xc98b4c: // 4C 8B C9 : mov r9, rcx
517 case 0xd2b60f: // 0f b6 d2 : movzx edx, dl
518 case 0xca2b48: // 48 2b ca : sub rcx, rdx
519 case 0x10b70f: // 0f b7 10 : movzx edx, WORD PTR [rax]
520 case 0xc00b4d: // 3d 0b c0 : or r8, r8
521 case 0xd18b48: // 48 8b d1 : mov rdx, rcx
522 case 0xdc8b4c: // 4c 8b dc : mov r11, rsp
523 case 0xd18b4c: // 4c 8b d1 : mov r10, rcx
526 case 0xec8348: // 48 83 ec XX : sub rsp, XX
527 case 0xf88349: // 49 83 f8 XX : cmp r8, XX
528 case 0x588948: // 48 89 58 XX : mov QWORD PTR[rax + XX], rbx
531 case 0xec8148: // 48 81 EC XX XX XX XX : sub rsp, XXXXXXXX
534 case 0x058b48: // 48 8b 05 XX XX XX XX :
535 // mov rax, QWORD PTR [rip + XXXXXXXX]
536 case 0x25ff48: // 48 ff 25 XX XX XX XX :
537 // rex.W jmp QWORD PTR [rip + XXXXXXXX]
539 // Instructions having offset relative to 'rip' need offset adjustment.
544 case 0x2444c7: // C7 44 24 XX YY YY YY YY
545 // mov dword ptr [rsp + XX], YYYYYYYY
549 switch (*(u32
*)(address
)) {
550 case 0x24448b48: // 48 8b 44 24 XX : mov rax, QWORD ptr [rsp + XX]
551 case 0x246c8948: // 48 89 6C 24 XX : mov QWORD ptr [rsp + XX], rbp
552 case 0x245c8948: // 48 89 5c 24 XX : mov QWORD PTR [rsp + XX], rbx
553 case 0x24748948: // 48 89 74 24 XX : mov QWORD PTR [rsp + XX], rsi
559 switch (*(u8
*)address
) {
560 case 0xA1: // A1 XX XX XX XX : mov eax, dword ptr ds:[XXXXXXXX]
563 switch (*(u16
*)address
) {
564 case 0x458B: // 8B 45 XX : mov eax, dword ptr [ebp + XX]
565 case 0x5D8B: // 8B 5D XX : mov ebx, dword ptr [ebp + XX]
566 case 0x7D8B: // 8B 7D XX : mov edi, dword ptr [ebp + XX]
567 case 0xEC83: // 83 EC XX : sub esp, XX
568 case 0x75FF: // FF 75 XX : push dword ptr [ebp + XX]
570 case 0xC1F7: // F7 C1 XX YY ZZ WW : test ecx, WWZZYYXX
571 case 0x25FF: // FF 25 XX YY ZZ WW : jmp dword ptr ds:[WWZZYYXX]
573 case 0x3D83: // 83 3D XX YY ZZ WW TT : cmp TT, WWZZYYXX
575 case 0x7D83: // 83 7D XX YY : cmp dword ptr [ebp + XX], YY
579 switch (0x00FFFFFF & *(u32
*)address
) {
580 case 0x24448A: // 8A 44 24 XX : mov eal, dword ptr [esp + XX]
581 case 0x24448B: // 8B 44 24 XX : mov eax, dword ptr [esp + XX]
582 case 0x244C8B: // 8B 4C 24 XX : mov ecx, dword ptr [esp + XX]
583 case 0x24548B: // 8B 54 24 XX : mov edx, dword ptr [esp + XX]
584 case 0x24748B: // 8B 74 24 XX : mov esi, dword ptr [esp + XX]
585 case 0x247C8B: // 8B 7C 24 XX : mov edi, dword ptr [esp + XX]
589 switch (*(u32
*)address
) {
590 case 0x2444B60F: // 0F B6 44 24 XX : movzx eax, byte ptr [esp + XX]
595 // Unknown instruction!
596 // FIXME: Unknown instruction failures might happen when we add a new
597 // interceptor or a new compiler version. In either case, they should result
598 // in visible and readable error messages. However, merely calling abort()
599 // leads to an infinite recursion in CheckFailed.
600 InterceptionFailed();
604 // Returns 0 on error.
605 static size_t RoundUpToInstrBoundary(size_t size
, uptr address
) {
607 while (cursor
< size
) {
608 size_t instruction_size
= GetInstructionSize(address
+ cursor
);
609 if (!instruction_size
)
611 cursor
+= instruction_size
;
616 static bool CopyInstructions(uptr to
, uptr from
, size_t size
) {
618 while (cursor
!= size
) {
619 size_t rel_offset
= 0;
620 size_t instruction_size
= GetInstructionSize(from
+ cursor
, &rel_offset
);
621 _memcpy((void*)(to
+ cursor
), (void*)(from
+ cursor
),
622 (size_t)instruction_size
);
624 uptr delta
= to
- from
;
625 uptr relocated_offset
= *(u32
*)(to
+ cursor
+ rel_offset
) - delta
;
626 #if SANITIZER_WINDOWS64
627 if (relocated_offset
+ 0x80000000U
>= 0xFFFFFFFFU
)
630 *(u32
*)(to
+ cursor
+ rel_offset
) = relocated_offset
;
632 cursor
+= instruction_size
;
638 #if !SANITIZER_WINDOWS64
639 bool OverrideFunctionWithDetour(
640 uptr old_func
, uptr new_func
, uptr
*orig_old_func
) {
641 const int kDetourHeaderLen
= 5;
642 const u16 kDetourInstruction
= 0xFF8B;
644 uptr header
= (uptr
)old_func
- kDetourHeaderLen
;
645 uptr patch_length
= kDetourHeaderLen
+ kShortJumpInstructionLength
;
647 // Validate that the function is hookable.
648 if (*(u16
*)old_func
!= kDetourInstruction
||
649 !IsMemoryPadding(header
, kDetourHeaderLen
))
652 // Change memory protection to writable.
653 DWORD protection
= 0;
654 if (!ChangeMemoryProtection(header
, patch_length
, &protection
))
657 // Write a relative jump to the redirected function.
658 WriteJumpInstruction(header
, new_func
);
660 // Write the short jump to the function prefix.
661 WriteShortJumpInstruction(old_func
, header
);
663 // Restore previous memory protection.
664 if (!RestoreMemoryProtection(header
, patch_length
, protection
))
668 *orig_old_func
= old_func
+ kShortJumpInstructionLength
;
674 bool OverrideFunctionWithRedirectJump(
675 uptr old_func
, uptr new_func
, uptr
*orig_old_func
) {
676 // Check whether the first instruction is a relative jump.
677 if (*(u8
*)old_func
!= 0xE9)
681 uptr relative_offset
= *(u32
*)(old_func
+ 1);
682 uptr absolute_target
= old_func
+ relative_offset
+ kJumpInstructionLength
;
683 *orig_old_func
= absolute_target
;
686 #if SANITIZER_WINDOWS64
687 // If needed, get memory space for a trampoline jump.
688 uptr trampoline
= AllocateMemoryForTrampoline(old_func
, kDirectBranchLength
);
691 WriteDirectBranch(trampoline
, new_func
);
694 // Change memory protection to writable.
695 DWORD protection
= 0;
696 if (!ChangeMemoryProtection(old_func
, kJumpInstructionLength
, &protection
))
699 // Write a relative jump to the redirected function.
700 WriteJumpInstruction(old_func
, FIRST_32_SECOND_64(new_func
, trampoline
));
702 // Restore previous memory protection.
703 if (!RestoreMemoryProtection(old_func
, kJumpInstructionLength
, protection
))
709 bool OverrideFunctionWithHotPatch(
710 uptr old_func
, uptr new_func
, uptr
*orig_old_func
) {
711 const int kHotPatchHeaderLen
= kBranchLength
;
713 uptr header
= (uptr
)old_func
- kHotPatchHeaderLen
;
714 uptr patch_length
= kHotPatchHeaderLen
+ kShortJumpInstructionLength
;
716 // Validate that the function is hot patchable.
717 size_t instruction_size
= GetInstructionSize(old_func
);
718 if (instruction_size
< kShortJumpInstructionLength
||
719 !FunctionHasPadding(old_func
, kHotPatchHeaderLen
))
723 // Put the needed instructions into the trampoline bytes.
724 uptr trampoline_length
= instruction_size
+ kDirectBranchLength
;
725 uptr trampoline
= AllocateMemoryForTrampoline(old_func
, trampoline_length
);
728 if (!CopyInstructions(trampoline
, old_func
, instruction_size
))
730 WriteDirectBranch(trampoline
+ instruction_size
,
731 old_func
+ instruction_size
);
732 *orig_old_func
= trampoline
;
735 // If needed, get memory space for indirect address.
736 uptr indirect_address
= 0;
737 #if SANITIZER_WINDOWS64
738 indirect_address
= AllocateMemoryForTrampoline(old_func
, kAddressLength
);
739 if (!indirect_address
)
743 // Change memory protection to writable.
744 DWORD protection
= 0;
745 if (!ChangeMemoryProtection(header
, patch_length
, &protection
))
748 // Write jumps to the redirected function.
749 WriteBranch(header
, indirect_address
, new_func
);
750 WriteShortJumpInstruction(old_func
, header
);
752 // Restore previous memory protection.
753 if (!RestoreMemoryProtection(header
, patch_length
, protection
))
759 bool OverrideFunctionWithTrampoline(
760 uptr old_func
, uptr new_func
, uptr
*orig_old_func
) {
762 size_t instructions_length
= kBranchLength
;
763 size_t padding_length
= 0;
764 uptr indirect_address
= 0;
767 // Find out the number of bytes of the instructions we need to copy
768 // to the trampoline.
769 instructions_length
= RoundUpToInstrBoundary(kBranchLength
, old_func
);
770 if (!instructions_length
)
773 // Put the needed instructions into the trampoline bytes.
774 uptr trampoline_length
= instructions_length
+ kDirectBranchLength
;
775 uptr trampoline
= AllocateMemoryForTrampoline(old_func
, trampoline_length
);
778 if (!CopyInstructions(trampoline
, old_func
, instructions_length
))
780 WriteDirectBranch(trampoline
+ instructions_length
,
781 old_func
+ instructions_length
);
782 *orig_old_func
= trampoline
;
785 #if SANITIZER_WINDOWS64
786 // Check if the targeted address can be encoded in the function padding.
787 // Otherwise, allocate it in the trampoline region.
788 if (IsMemoryPadding(old_func
- kAddressLength
, kAddressLength
)) {
789 indirect_address
= old_func
- kAddressLength
;
790 padding_length
= kAddressLength
;
792 indirect_address
= AllocateMemoryForTrampoline(old_func
, kAddressLength
);
793 if (!indirect_address
)
798 // Change memory protection to writable.
799 uptr patch_address
= old_func
- padding_length
;
800 uptr patch_length
= instructions_length
+ padding_length
;
801 DWORD protection
= 0;
802 if (!ChangeMemoryProtection(patch_address
, patch_length
, &protection
))
805 // Patch the original function.
806 WriteBranch(old_func
, indirect_address
, new_func
);
808 // Restore previous memory protection.
809 if (!RestoreMemoryProtection(patch_address
, patch_length
, protection
))
815 bool OverrideFunction(
816 uptr old_func
, uptr new_func
, uptr
*orig_old_func
) {
817 #if !SANITIZER_WINDOWS64
818 if (OverrideFunctionWithDetour(old_func
, new_func
, orig_old_func
))
821 if (OverrideFunctionWithRedirectJump(old_func
, new_func
, orig_old_func
))
823 if (OverrideFunctionWithHotPatch(old_func
, new_func
, orig_old_func
))
825 if (OverrideFunctionWithTrampoline(old_func
, new_func
, orig_old_func
))
830 static void **InterestingDLLsAvailable() {
831 static const char *InterestingDLLs
[] = {
833 "msvcr110.dll", // VS2012
834 "msvcr120.dll", // VS2013
835 "vcruntime140.dll", // VS2015
836 "ucrtbase.dll", // Universal CRT
837 // NTDLL should go last as it exports some functions that we should
838 // override in the CRT [presumably only used internally].
840 static void *result
[ARRAY_SIZE(InterestingDLLs
)] = { 0 };
842 for (size_t i
= 0, j
= 0; InterestingDLLs
[i
]; ++i
) {
843 if (HMODULE h
= GetModuleHandleA(InterestingDLLs
[i
]))
844 result
[j
++] = (void *)h
;
851 // Utility for reading loaded PE images.
852 template <typename T
> class RVAPtr
{
854 RVAPtr(void *module
, uptr rva
)
855 : ptr_(reinterpret_cast<T
*>(reinterpret_cast<char *>(module
) + rva
)) {}
856 operator T
*() { return ptr_
; }
857 T
*operator->() { return ptr_
; }
858 T
*operator++() { return ++ptr_
; }
865 // Internal implementation of GetProcAddress. At least since Windows 8,
866 // GetProcAddress appears to initialize DLLs before returning function pointers
867 // into them. This is problematic for the sanitizers, because they typically
868 // want to intercept malloc *before* MSVCRT initializes. Our internal
869 // implementation walks the export list manually without doing initialization.
870 uptr
InternalGetProcAddress(void *module
, const char *func_name
) {
871 // Check that the module header is full and present.
872 RVAPtr
<IMAGE_DOS_HEADER
> dos_stub(module
, 0);
873 RVAPtr
<IMAGE_NT_HEADERS
> headers(module
, dos_stub
->e_lfanew
);
874 if (!module
|| dos_stub
->e_magic
!= IMAGE_DOS_SIGNATURE
|| // "MZ"
875 headers
->Signature
!= IMAGE_NT_SIGNATURE
|| // "PE\0\0"
876 headers
->FileHeader
.SizeOfOptionalHeader
<
877 sizeof(IMAGE_OPTIONAL_HEADER
)) {
881 IMAGE_DATA_DIRECTORY
*export_directory
=
882 &headers
->OptionalHeader
.DataDirectory
[IMAGE_DIRECTORY_ENTRY_EXPORT
];
883 if (export_directory
->Size
== 0)
885 RVAPtr
<IMAGE_EXPORT_DIRECTORY
> exports(module
,
886 export_directory
->VirtualAddress
);
887 RVAPtr
<DWORD
> functions(module
, exports
->AddressOfFunctions
);
888 RVAPtr
<DWORD
> names(module
, exports
->AddressOfNames
);
889 RVAPtr
<WORD
> ordinals(module
, exports
->AddressOfNameOrdinals
);
891 for (DWORD i
= 0; i
< exports
->NumberOfNames
; i
++) {
892 RVAPtr
<char> name(module
, names
[i
]);
893 if (!strcmp(func_name
, name
)) {
894 DWORD index
= ordinals
[i
];
895 RVAPtr
<char> func(module
, functions
[index
]);
897 // Handle forwarded functions.
898 DWORD offset
= functions
[index
];
899 if (offset
>= export_directory
->VirtualAddress
&&
900 offset
< export_directory
->VirtualAddress
+ export_directory
->Size
) {
901 // An entry for a forwarded function is a string with the following
902 // format: "<module> . <function_name>" that is stored into the
903 // exported directory.
904 char function_name
[256];
905 size_t funtion_name_length
= _strlen(func
);
906 if (funtion_name_length
>= sizeof(function_name
) - 1)
907 InterceptionFailed();
909 _memcpy(function_name
, func
, funtion_name_length
);
910 function_name
[funtion_name_length
] = '\0';
911 char* separator
= _strchr(function_name
, '.');
913 InterceptionFailed();
916 void* redirected_module
= GetModuleHandleA(function_name
);
917 if (!redirected_module
)
918 InterceptionFailed();
919 return InternalGetProcAddress(redirected_module
, separator
+ 1);
922 return (uptr
)(char *)func
;
929 bool OverrideFunction(
930 const char *func_name
, uptr new_func
, uptr
*orig_old_func
) {
932 void **DLLs
= InterestingDLLsAvailable();
933 for (size_t i
= 0; DLLs
[i
]; ++i
) {
934 uptr func_addr
= InternalGetProcAddress(DLLs
[i
], func_name
);
936 OverrideFunction(func_addr
, new_func
, orig_old_func
)) {
943 bool OverrideImportedFunction(const char *module_to_patch
,
944 const char *imported_module
,
945 const char *function_name
, uptr new_function
,
946 uptr
*orig_old_func
) {
947 HMODULE module
= GetModuleHandleA(module_to_patch
);
951 // Check that the module header is full and present.
952 RVAPtr
<IMAGE_DOS_HEADER
> dos_stub(module
, 0);
953 RVAPtr
<IMAGE_NT_HEADERS
> headers(module
, dos_stub
->e_lfanew
);
954 if (!module
|| dos_stub
->e_magic
!= IMAGE_DOS_SIGNATURE
|| // "MZ"
955 headers
->Signature
!= IMAGE_NT_SIGNATURE
|| // "PE\0\0"
956 headers
->FileHeader
.SizeOfOptionalHeader
<
957 sizeof(IMAGE_OPTIONAL_HEADER
)) {
961 IMAGE_DATA_DIRECTORY
*import_directory
=
962 &headers
->OptionalHeader
.DataDirectory
[IMAGE_DIRECTORY_ENTRY_IMPORT
];
964 // Iterate the list of imported DLLs. FirstThunk will be null for the last
966 RVAPtr
<IMAGE_IMPORT_DESCRIPTOR
> imports(module
,
967 import_directory
->VirtualAddress
);
968 for (; imports
->FirstThunk
!= 0; ++imports
) {
969 RVAPtr
<const char> modname(module
, imports
->Name
);
970 if (_stricmp(&*modname
, imported_module
) == 0)
973 if (imports
->FirstThunk
== 0)
976 // We have two parallel arrays: the import address table (IAT) and the table
977 // of names. They start out containing the same data, but the loader rewrites
978 // the IAT to hold imported addresses and leaves the name table in
979 // OriginalFirstThunk alone.
980 RVAPtr
<IMAGE_THUNK_DATA
> name_table(module
, imports
->OriginalFirstThunk
);
981 RVAPtr
<IMAGE_THUNK_DATA
> iat(module
, imports
->FirstThunk
);
982 for (; name_table
->u1
.Ordinal
!= 0; ++name_table
, ++iat
) {
983 if (!IMAGE_SNAP_BY_ORDINAL(name_table
->u1
.Ordinal
)) {
984 RVAPtr
<IMAGE_IMPORT_BY_NAME
> import_by_name(
985 module
, name_table
->u1
.ForwarderString
);
986 const char *funcname
= &import_by_name
->Name
[0];
987 if (strcmp(funcname
, function_name
) == 0)
991 if (name_table
->u1
.Ordinal
== 0)
994 // Now we have the correct IAT entry. Do the swap. We have to make the page
997 *orig_old_func
= iat
->u1
.AddressOfData
;
998 DWORD old_prot
, unused_prot
;
999 if (!VirtualProtect(&iat
->u1
.AddressOfData
, 4, PAGE_EXECUTE_READWRITE
,
1002 iat
->u1
.AddressOfData
= new_function
;
1003 if (!VirtualProtect(&iat
->u1
.AddressOfData
, 4, old_prot
, &unused_prot
))
1004 return false; // Not clear if this failure bothers us.
1008 } // namespace __interception