1*a7c257b0Skamil //===-- interception_linux.cc -----------------------------------*- C++ -*-===//
2*a7c257b0Skamil //
3*a7c257b0Skamil // The LLVM Compiler Infrastructure
4*a7c257b0Skamil //
5*a7c257b0Skamil // This file is distributed under the University of Illinois Open Source
6*a7c257b0Skamil // License. See LICENSE.TXT for details.
7*a7c257b0Skamil //
8*a7c257b0Skamil //===----------------------------------------------------------------------===//
9*a7c257b0Skamil //
10*a7c257b0Skamil // This file is a part of AddressSanitizer, an address sanity checker.
11*a7c257b0Skamil //
12*a7c257b0Skamil // Windows-specific interception methods.
13*a7c257b0Skamil //
14*a7c257b0Skamil // This file is implementing several hooking techniques to intercept calls
15*a7c257b0Skamil // to functions. The hooks are dynamically installed by modifying the assembly
16*a7c257b0Skamil // code.
17*a7c257b0Skamil //
18*a7c257b0Skamil // The hooking techniques are making assumptions on the way the code is
19*a7c257b0Skamil // generated and are safe under these assumptions.
20*a7c257b0Skamil //
21*a7c257b0Skamil // On 64-bit architecture, there is no direct 64-bit jump instruction. To allow
22*a7c257b0Skamil // arbitrary branching on the whole memory space, the notion of trampoline
23*a7c257b0Skamil // region is used. A trampoline region is a memory space withing 2G boundary
24*a7c257b0Skamil // where it is safe to add custom assembly code to build 64-bit jumps.
25*a7c257b0Skamil //
26*a7c257b0Skamil // Hooking techniques
27*a7c257b0Skamil // ==================
28*a7c257b0Skamil //
29*a7c257b0Skamil // 1) Detour
30*a7c257b0Skamil //
31*a7c257b0Skamil // The Detour hooking technique is assuming the presence of an header with
32*a7c257b0Skamil // padding and an overridable 2-bytes nop instruction (mov edi, edi). The
33*a7c257b0Skamil // nop instruction can safely be replaced by a 2-bytes jump without any need
34*a7c257b0Skamil // to save the instruction. A jump to the target is encoded in the function
35*a7c257b0Skamil // header and the nop instruction is replaced by a short jump to the header.
36*a7c257b0Skamil //
37*a7c257b0Skamil // head: 5 x nop head: jmp <hook>
38*a7c257b0Skamil // func: mov edi, edi --> func: jmp short <head>
39*a7c257b0Skamil // [...] real: [...]
40*a7c257b0Skamil //
41*a7c257b0Skamil // This technique is only implemented on 32-bit architecture.
42*a7c257b0Skamil // Most of the time, Windows API are hookable with the detour technique.
43*a7c257b0Skamil //
44*a7c257b0Skamil // 2) Redirect Jump
45*a7c257b0Skamil //
46*a7c257b0Skamil // The redirect jump is applicable when the first instruction is a direct
47*a7c257b0Skamil // jump. The instruction is replaced by jump to the hook.
48*a7c257b0Skamil //
49*a7c257b0Skamil // func: jmp <label> --> func: jmp <hook>
50*a7c257b0Skamil //
51*a7c257b0Skamil // On an 64-bit architecture, a trampoline is inserted.
52*a7c257b0Skamil //
53*a7c257b0Skamil // func: jmp <label> --> func: jmp <tramp>
54*a7c257b0Skamil // [...]
55*a7c257b0Skamil //
56*a7c257b0Skamil // [trampoline]
57*a7c257b0Skamil // tramp: jmp QWORD [addr]
58*a7c257b0Skamil // addr: .bytes <hook>
59*a7c257b0Skamil //
60*a7c257b0Skamil // Note: <real> is equilavent to <label>.
61*a7c257b0Skamil //
62*a7c257b0Skamil // 3) HotPatch
63*a7c257b0Skamil //
64*a7c257b0Skamil // The HotPatch hooking is assuming the presence of an header with padding
65*a7c257b0Skamil // and a first instruction with at least 2-bytes.
66*a7c257b0Skamil //
67*a7c257b0Skamil // The reason to enforce the 2-bytes limitation is to provide the minimal
68*a7c257b0Skamil // space to encode a short jump. HotPatch technique is only rewriting one
69*a7c257b0Skamil // instruction to avoid breaking a sequence of instructions containing a
70*a7c257b0Skamil // branching target.
71*a7c257b0Skamil //
72*a7c257b0Skamil // Assumptions are enforced by MSVC compiler by using the /HOTPATCH flag.
73*a7c257b0Skamil // see: https://msdn.microsoft.com/en-us/library/ms173507.aspx
74*a7c257b0Skamil // Default padding length is 5 bytes in 32-bits and 6 bytes in 64-bits.
75*a7c257b0Skamil //
76*a7c257b0Skamil // head: 5 x nop head: jmp <hook>
77*a7c257b0Skamil // func: <instr> --> func: jmp short <head>
78*a7c257b0Skamil // [...] body: [...]
79*a7c257b0Skamil //
80*a7c257b0Skamil // [trampoline]
81*a7c257b0Skamil // real: <instr>
82*a7c257b0Skamil // jmp <body>
83*a7c257b0Skamil //
84*a7c257b0Skamil // On an 64-bit architecture:
85*a7c257b0Skamil //
86*a7c257b0Skamil // head: 6 x nop head: jmp QWORD [addr1]
87*a7c257b0Skamil // func: <instr> --> func: jmp short <head>
88*a7c257b0Skamil // [...] body: [...]
89*a7c257b0Skamil //
90*a7c257b0Skamil // [trampoline]
91*a7c257b0Skamil // addr1: .bytes <hook>
92*a7c257b0Skamil // real: <instr>
93*a7c257b0Skamil // jmp QWORD [addr2]
94*a7c257b0Skamil // addr2: .bytes <body>
95*a7c257b0Skamil //
96*a7c257b0Skamil // 4) Trampoline
97*a7c257b0Skamil //
98*a7c257b0Skamil // The Trampoline hooking technique is the most aggressive one. It is
99*a7c257b0Skamil // assuming that there is a sequence of instructions that can be safely
100*a7c257b0Skamil // replaced by a jump (enough room and no incoming branches).
101*a7c257b0Skamil //
102*a7c257b0Skamil // Unfortunately, these assumptions can't be safely presumed and code may
103*a7c257b0Skamil // be broken after hooking.
104*a7c257b0Skamil //
105*a7c257b0Skamil // func: <instr> --> func: jmp <hook>
106*a7c257b0Skamil // <instr>
107*a7c257b0Skamil // [...] body: [...]
108*a7c257b0Skamil //
109*a7c257b0Skamil // [trampoline]
110*a7c257b0Skamil // real: <instr>
111*a7c257b0Skamil // <instr>
112*a7c257b0Skamil // jmp <body>
113*a7c257b0Skamil //
114*a7c257b0Skamil // On an 64-bit architecture:
115*a7c257b0Skamil //
116*a7c257b0Skamil // func: <instr> --> func: jmp QWORD [addr1]
117*a7c257b0Skamil // <instr>
118*a7c257b0Skamil // [...] body: [...]
119*a7c257b0Skamil //
120*a7c257b0Skamil // [trampoline]
121*a7c257b0Skamil // addr1: .bytes <hook>
122*a7c257b0Skamil // real: <instr>
123*a7c257b0Skamil // <instr>
124*a7c257b0Skamil // jmp QWORD [addr2]
125*a7c257b0Skamil // addr2: .bytes <body>
126*a7c257b0Skamil //===----------------------------------------------------------------------===//
127*a7c257b0Skamil
128*a7c257b0Skamil #include "interception.h"
129*a7c257b0Skamil
130*a7c257b0Skamil #if SANITIZER_WINDOWS
131*a7c257b0Skamil #include "sanitizer_common/sanitizer_platform.h"
132*a7c257b0Skamil #define WIN32_LEAN_AND_MEAN
133*a7c257b0Skamil #include <windows.h>
134*a7c257b0Skamil
135*a7c257b0Skamil namespace __interception {
136*a7c257b0Skamil
137*a7c257b0Skamil static const int kAddressLength = FIRST_32_SECOND_64(4, 8);
138*a7c257b0Skamil static const int kJumpInstructionLength = 5;
139*a7c257b0Skamil static const int kShortJumpInstructionLength = 2;
140*a7c257b0Skamil static const int kIndirectJumpInstructionLength = 6;
141*a7c257b0Skamil static const int kBranchLength =
142*a7c257b0Skamil FIRST_32_SECOND_64(kJumpInstructionLength, kIndirectJumpInstructionLength);
143*a7c257b0Skamil static const int kDirectBranchLength = kBranchLength + kAddressLength;
144*a7c257b0Skamil
InterceptionFailed()145*a7c257b0Skamil static void InterceptionFailed() {
146*a7c257b0Skamil // Do we have a good way to abort with an error message here?
147*a7c257b0Skamil __debugbreak();
148*a7c257b0Skamil }
149*a7c257b0Skamil
DistanceIsWithin2Gig(uptr from,uptr target)150*a7c257b0Skamil static bool DistanceIsWithin2Gig(uptr from, uptr target) {
151*a7c257b0Skamil #if SANITIZER_WINDOWS64
152*a7c257b0Skamil if (from < target)
153*a7c257b0Skamil return target - from <= (uptr)0x7FFFFFFFU;
154*a7c257b0Skamil else
155*a7c257b0Skamil return from - target <= (uptr)0x80000000U;
156*a7c257b0Skamil #else
157*a7c257b0Skamil // In a 32-bit address space, the address calculation will wrap, so this check
158*a7c257b0Skamil // is unnecessary.
159*a7c257b0Skamil return true;
160*a7c257b0Skamil #endif
161*a7c257b0Skamil }
162*a7c257b0Skamil
GetMmapGranularity()163*a7c257b0Skamil static uptr GetMmapGranularity() {
164*a7c257b0Skamil SYSTEM_INFO si;
165*a7c257b0Skamil GetSystemInfo(&si);
166*a7c257b0Skamil return si.dwAllocationGranularity;
167*a7c257b0Skamil }
168*a7c257b0Skamil
RoundUpTo(uptr size,uptr boundary)169*a7c257b0Skamil static uptr RoundUpTo(uptr size, uptr boundary) {
170*a7c257b0Skamil return (size + boundary - 1) & ~(boundary - 1);
171*a7c257b0Skamil }
172*a7c257b0Skamil
173*a7c257b0Skamil // FIXME: internal_str* and internal_mem* functions should be moved from the
174*a7c257b0Skamil // ASan sources into interception/.
175*a7c257b0Skamil
_strlen(const char * str)176*a7c257b0Skamil static size_t _strlen(const char *str) {
177*a7c257b0Skamil const char* p = str;
178*a7c257b0Skamil while (*p != '\0') ++p;
179*a7c257b0Skamil return p - str;
180*a7c257b0Skamil }
181*a7c257b0Skamil
_strchr(char * str,char c)182*a7c257b0Skamil static char* _strchr(char* str, char c) {
183*a7c257b0Skamil while (*str) {
184*a7c257b0Skamil if (*str == c)
185*a7c257b0Skamil return str;
186*a7c257b0Skamil ++str;
187*a7c257b0Skamil }
188*a7c257b0Skamil return nullptr;
189*a7c257b0Skamil }
190*a7c257b0Skamil
_memset(void * p,int value,size_t sz)191*a7c257b0Skamil static void _memset(void *p, int value, size_t sz) {
192*a7c257b0Skamil for (size_t i = 0; i < sz; ++i)
193*a7c257b0Skamil ((char*)p)[i] = (char)value;
194*a7c257b0Skamil }
195*a7c257b0Skamil
_memcpy(void * dst,void * src,size_t sz)196*a7c257b0Skamil static void _memcpy(void *dst, void *src, size_t sz) {
197*a7c257b0Skamil char *dst_c = (char*)dst,
198*a7c257b0Skamil *src_c = (char*)src;
199*a7c257b0Skamil for (size_t i = 0; i < sz; ++i)
200*a7c257b0Skamil dst_c[i] = src_c[i];
201*a7c257b0Skamil }
202*a7c257b0Skamil
ChangeMemoryProtection(uptr address,uptr size,DWORD * old_protection)203*a7c257b0Skamil static bool ChangeMemoryProtection(
204*a7c257b0Skamil uptr address, uptr size, DWORD *old_protection) {
205*a7c257b0Skamil return ::VirtualProtect((void*)address, size,
206*a7c257b0Skamil PAGE_EXECUTE_READWRITE,
207*a7c257b0Skamil old_protection) != FALSE;
208*a7c257b0Skamil }
209*a7c257b0Skamil
RestoreMemoryProtection(uptr address,uptr size,DWORD old_protection)210*a7c257b0Skamil static bool RestoreMemoryProtection(
211*a7c257b0Skamil uptr address, uptr size, DWORD old_protection) {
212*a7c257b0Skamil DWORD unused;
213*a7c257b0Skamil return ::VirtualProtect((void*)address, size,
214*a7c257b0Skamil old_protection,
215*a7c257b0Skamil &unused) != FALSE;
216*a7c257b0Skamil }
217*a7c257b0Skamil
IsMemoryPadding(uptr address,uptr size)218*a7c257b0Skamil static bool IsMemoryPadding(uptr address, uptr size) {
219*a7c257b0Skamil u8* function = (u8*)address;
220*a7c257b0Skamil for (size_t i = 0; i < size; ++i)
221*a7c257b0Skamil if (function[i] != 0x90 && function[i] != 0xCC)
222*a7c257b0Skamil return false;
223*a7c257b0Skamil return true;
224*a7c257b0Skamil }
225*a7c257b0Skamil
226*a7c257b0Skamil static const u8 kHintNop8Bytes[] = {
227*a7c257b0Skamil 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00
228*a7c257b0Skamil };
229*a7c257b0Skamil
230*a7c257b0Skamil template<class T>
FunctionHasPrefix(uptr address,const T & pattern)231*a7c257b0Skamil static bool FunctionHasPrefix(uptr address, const T &pattern) {
232*a7c257b0Skamil u8* function = (u8*)address - sizeof(pattern);
233*a7c257b0Skamil for (size_t i = 0; i < sizeof(pattern); ++i)
234*a7c257b0Skamil if (function[i] != pattern[i])
235*a7c257b0Skamil return false;
236*a7c257b0Skamil return true;
237*a7c257b0Skamil }
238*a7c257b0Skamil
FunctionHasPadding(uptr address,uptr size)239*a7c257b0Skamil static bool FunctionHasPadding(uptr address, uptr size) {
240*a7c257b0Skamil if (IsMemoryPadding(address - size, size))
241*a7c257b0Skamil return true;
242*a7c257b0Skamil if (size <= sizeof(kHintNop8Bytes) &&
243*a7c257b0Skamil FunctionHasPrefix(address, kHintNop8Bytes))
244*a7c257b0Skamil return true;
245*a7c257b0Skamil return false;
246*a7c257b0Skamil }
247*a7c257b0Skamil
WritePadding(uptr from,uptr size)248*a7c257b0Skamil static void WritePadding(uptr from, uptr size) {
249*a7c257b0Skamil _memset((void*)from, 0xCC, (size_t)size);
250*a7c257b0Skamil }
251*a7c257b0Skamil
WriteJumpInstruction(uptr from,uptr target)252*a7c257b0Skamil static void WriteJumpInstruction(uptr from, uptr target) {
253*a7c257b0Skamil if (!DistanceIsWithin2Gig(from + kJumpInstructionLength, target))
254*a7c257b0Skamil InterceptionFailed();
255*a7c257b0Skamil ptrdiff_t offset = target - from - kJumpInstructionLength;
256*a7c257b0Skamil *(u8*)from = 0xE9;
257*a7c257b0Skamil *(u32*)(from + 1) = offset;
258*a7c257b0Skamil }
259*a7c257b0Skamil
WriteShortJumpInstruction(uptr from,uptr target)260*a7c257b0Skamil static void WriteShortJumpInstruction(uptr from, uptr target) {
261*a7c257b0Skamil sptr offset = target - from - kShortJumpInstructionLength;
262*a7c257b0Skamil if (offset < -128 || offset > 127)
263*a7c257b0Skamil InterceptionFailed();
264*a7c257b0Skamil *(u8*)from = 0xEB;
265*a7c257b0Skamil *(u8*)(from + 1) = (u8)offset;
266*a7c257b0Skamil }
267*a7c257b0Skamil
268*a7c257b0Skamil #if SANITIZER_WINDOWS64
WriteIndirectJumpInstruction(uptr from,uptr indirect_target)269*a7c257b0Skamil static void WriteIndirectJumpInstruction(uptr from, uptr indirect_target) {
270*a7c257b0Skamil // jmp [rip + <offset>] = FF 25 <offset> where <offset> is a relative
271*a7c257b0Skamil // offset.
272*a7c257b0Skamil // The offset is the distance from then end of the jump instruction to the
273*a7c257b0Skamil // memory location containing the targeted address. The displacement is still
274*a7c257b0Skamil // 32-bit in x64, so indirect_target must be located within +/- 2GB range.
275*a7c257b0Skamil int offset = indirect_target - from - kIndirectJumpInstructionLength;
276*a7c257b0Skamil if (!DistanceIsWithin2Gig(from + kIndirectJumpInstructionLength,
277*a7c257b0Skamil indirect_target)) {
278*a7c257b0Skamil InterceptionFailed();
279*a7c257b0Skamil }
280*a7c257b0Skamil *(u16*)from = 0x25FF;
281*a7c257b0Skamil *(u32*)(from + 2) = offset;
282*a7c257b0Skamil }
283*a7c257b0Skamil #endif
284*a7c257b0Skamil
WriteBranch(uptr from,uptr indirect_target,uptr target)285*a7c257b0Skamil static void WriteBranch(
286*a7c257b0Skamil uptr from, uptr indirect_target, uptr target) {
287*a7c257b0Skamil #if SANITIZER_WINDOWS64
288*a7c257b0Skamil WriteIndirectJumpInstruction(from, indirect_target);
289*a7c257b0Skamil *(u64*)indirect_target = target;
290*a7c257b0Skamil #else
291*a7c257b0Skamil (void)indirect_target;
292*a7c257b0Skamil WriteJumpInstruction(from, target);
293*a7c257b0Skamil #endif
294*a7c257b0Skamil }
295*a7c257b0Skamil
WriteDirectBranch(uptr from,uptr target)296*a7c257b0Skamil static void WriteDirectBranch(uptr from, uptr target) {
297*a7c257b0Skamil #if SANITIZER_WINDOWS64
298*a7c257b0Skamil // Emit an indirect jump through immediately following bytes:
299*a7c257b0Skamil // jmp [rip + kBranchLength]
300*a7c257b0Skamil // .quad <target>
301*a7c257b0Skamil WriteBranch(from, from + kBranchLength, target);
302*a7c257b0Skamil #else
303*a7c257b0Skamil WriteJumpInstruction(from, target);
304*a7c257b0Skamil #endif
305*a7c257b0Skamil }
306*a7c257b0Skamil
307*a7c257b0Skamil struct TrampolineMemoryRegion {
308*a7c257b0Skamil uptr content;
309*a7c257b0Skamil uptr allocated_size;
310*a7c257b0Skamil uptr max_size;
311*a7c257b0Skamil };
312*a7c257b0Skamil
313*a7c257b0Skamil static const uptr kTrampolineScanLimitRange = 1 << 31; // 2 gig
314*a7c257b0Skamil static const int kMaxTrampolineRegion = 1024;
315*a7c257b0Skamil static TrampolineMemoryRegion TrampolineRegions[kMaxTrampolineRegion];
316*a7c257b0Skamil
AllocateTrampolineRegion(uptr image_address,size_t granularity)317*a7c257b0Skamil static void *AllocateTrampolineRegion(uptr image_address, size_t granularity) {
318*a7c257b0Skamil #if SANITIZER_WINDOWS64
319*a7c257b0Skamil uptr address = image_address;
320*a7c257b0Skamil uptr scanned = 0;
321*a7c257b0Skamil while (scanned < kTrampolineScanLimitRange) {
322*a7c257b0Skamil MEMORY_BASIC_INFORMATION info;
323*a7c257b0Skamil if (!::VirtualQuery((void*)address, &info, sizeof(info)))
324*a7c257b0Skamil return nullptr;
325*a7c257b0Skamil
326*a7c257b0Skamil // Check whether a region can be allocated at |address|.
327*a7c257b0Skamil if (info.State == MEM_FREE && info.RegionSize >= granularity) {
328*a7c257b0Skamil void *page = ::VirtualAlloc((void*)RoundUpTo(address, granularity),
329*a7c257b0Skamil granularity,
330*a7c257b0Skamil MEM_RESERVE | MEM_COMMIT,
331*a7c257b0Skamil PAGE_EXECUTE_READWRITE);
332*a7c257b0Skamil return page;
333*a7c257b0Skamil }
334*a7c257b0Skamil
335*a7c257b0Skamil // Move to the next region.
336*a7c257b0Skamil address = (uptr)info.BaseAddress + info.RegionSize;
337*a7c257b0Skamil scanned += info.RegionSize;
338*a7c257b0Skamil }
339*a7c257b0Skamil return nullptr;
340*a7c257b0Skamil #else
341*a7c257b0Skamil return ::VirtualAlloc(nullptr,
342*a7c257b0Skamil granularity,
343*a7c257b0Skamil MEM_RESERVE | MEM_COMMIT,
344*a7c257b0Skamil PAGE_EXECUTE_READWRITE);
345*a7c257b0Skamil #endif
346*a7c257b0Skamil }
347*a7c257b0Skamil
348*a7c257b0Skamil // Used by unittests to release mapped memory space.
TestOnlyReleaseTrampolineRegions()349*a7c257b0Skamil void TestOnlyReleaseTrampolineRegions() {
350*a7c257b0Skamil for (size_t bucket = 0; bucket < kMaxTrampolineRegion; ++bucket) {
351*a7c257b0Skamil TrampolineMemoryRegion *current = &TrampolineRegions[bucket];
352*a7c257b0Skamil if (current->content == 0)
353*a7c257b0Skamil return;
354*a7c257b0Skamil ::VirtualFree((void*)current->content, 0, MEM_RELEASE);
355*a7c257b0Skamil current->content = 0;
356*a7c257b0Skamil }
357*a7c257b0Skamil }
358*a7c257b0Skamil
AllocateMemoryForTrampoline(uptr image_address,size_t size)359*a7c257b0Skamil static uptr AllocateMemoryForTrampoline(uptr image_address, size_t size) {
360*a7c257b0Skamil // Find a region within 2G with enough space to allocate |size| bytes.
361*a7c257b0Skamil TrampolineMemoryRegion *region = nullptr;
362*a7c257b0Skamil for (size_t bucket = 0; bucket < kMaxTrampolineRegion; ++bucket) {
363*a7c257b0Skamil TrampolineMemoryRegion* current = &TrampolineRegions[bucket];
364*a7c257b0Skamil if (current->content == 0) {
365*a7c257b0Skamil // No valid region found, allocate a new region.
366*a7c257b0Skamil size_t bucket_size = GetMmapGranularity();
367*a7c257b0Skamil void *content = AllocateTrampolineRegion(image_address, bucket_size);
368*a7c257b0Skamil if (content == nullptr)
369*a7c257b0Skamil return 0U;
370*a7c257b0Skamil
371*a7c257b0Skamil current->content = (uptr)content;
372*a7c257b0Skamil current->allocated_size = 0;
373*a7c257b0Skamil current->max_size = bucket_size;
374*a7c257b0Skamil region = current;
375*a7c257b0Skamil break;
376*a7c257b0Skamil } else if (current->max_size - current->allocated_size > size) {
377*a7c257b0Skamil #if SANITIZER_WINDOWS64
378*a7c257b0Skamil // In 64-bits, the memory space must be allocated within 2G boundary.
379*a7c257b0Skamil uptr next_address = current->content + current->allocated_size;
380*a7c257b0Skamil if (next_address < image_address ||
381*a7c257b0Skamil next_address - image_address >= 0x7FFF0000)
382*a7c257b0Skamil continue;
383*a7c257b0Skamil #endif
384*a7c257b0Skamil // The space can be allocated in the current region.
385*a7c257b0Skamil region = current;
386*a7c257b0Skamil break;
387*a7c257b0Skamil }
388*a7c257b0Skamil }
389*a7c257b0Skamil
390*a7c257b0Skamil // Failed to find a region.
391*a7c257b0Skamil if (region == nullptr)
392*a7c257b0Skamil return 0U;
393*a7c257b0Skamil
394*a7c257b0Skamil // Allocate the space in the current region.
395*a7c257b0Skamil uptr allocated_space = region->content + region->allocated_size;
396*a7c257b0Skamil region->allocated_size += size;
397*a7c257b0Skamil WritePadding(allocated_space, size);
398*a7c257b0Skamil
399*a7c257b0Skamil return allocated_space;
400*a7c257b0Skamil }
401*a7c257b0Skamil
402*a7c257b0Skamil // Returns 0 on error.
GetInstructionSize(uptr address,size_t * rel_offset=nullptr)403*a7c257b0Skamil static size_t GetInstructionSize(uptr address, size_t* rel_offset = nullptr) {
404*a7c257b0Skamil switch (*(u64*)address) {
405*a7c257b0Skamil case 0x90909090909006EB: // stub: jmp over 6 x nop.
406*a7c257b0Skamil return 8;
407*a7c257b0Skamil }
408*a7c257b0Skamil
409*a7c257b0Skamil switch (*(u8*)address) {
410*a7c257b0Skamil case 0x90: // 90 : nop
411*a7c257b0Skamil return 1;
412*a7c257b0Skamil
413*a7c257b0Skamil case 0x50: // push eax / rax
414*a7c257b0Skamil case 0x51: // push ecx / rcx
415*a7c257b0Skamil case 0x52: // push edx / rdx
416*a7c257b0Skamil case 0x53: // push ebx / rbx
417*a7c257b0Skamil case 0x54: // push esp / rsp
418*a7c257b0Skamil case 0x55: // push ebp / rbp
419*a7c257b0Skamil case 0x56: // push esi / rsi
420*a7c257b0Skamil case 0x57: // push edi / rdi
421*a7c257b0Skamil case 0x5D: // pop ebp / rbp
422*a7c257b0Skamil return 1;
423*a7c257b0Skamil
424*a7c257b0Skamil case 0x6A: // 6A XX = push XX
425*a7c257b0Skamil return 2;
426*a7c257b0Skamil
427*a7c257b0Skamil case 0xb8: // b8 XX XX XX XX : mov eax, XX XX XX XX
428*a7c257b0Skamil case 0xB9: // b9 XX XX XX XX : mov ecx, XX XX XX XX
429*a7c257b0Skamil return 5;
430*a7c257b0Skamil
431*a7c257b0Skamil // Cannot overwrite control-instruction. Return 0 to indicate failure.
432*a7c257b0Skamil case 0xE9: // E9 XX XX XX XX : jmp <label>
433*a7c257b0Skamil case 0xE8: // E8 XX XX XX XX : call <func>
434*a7c257b0Skamil case 0xC3: // C3 : ret
435*a7c257b0Skamil case 0xEB: // EB XX : jmp XX (short jump)
436*a7c257b0Skamil case 0x70: // 7Y YY : jy XX (short conditional jump)
437*a7c257b0Skamil case 0x71:
438*a7c257b0Skamil case 0x72:
439*a7c257b0Skamil case 0x73:
440*a7c257b0Skamil case 0x74:
441*a7c257b0Skamil case 0x75:
442*a7c257b0Skamil case 0x76:
443*a7c257b0Skamil case 0x77:
444*a7c257b0Skamil case 0x78:
445*a7c257b0Skamil case 0x79:
446*a7c257b0Skamil case 0x7A:
447*a7c257b0Skamil case 0x7B:
448*a7c257b0Skamil case 0x7C:
449*a7c257b0Skamil case 0x7D:
450*a7c257b0Skamil case 0x7E:
451*a7c257b0Skamil case 0x7F:
452*a7c257b0Skamil return 0;
453*a7c257b0Skamil }
454*a7c257b0Skamil
455*a7c257b0Skamil switch (*(u16*)(address)) {
456*a7c257b0Skamil case 0x018A: // 8A 01 : mov al, byte ptr [ecx]
457*a7c257b0Skamil case 0xFF8B: // 8B FF : mov edi, edi
458*a7c257b0Skamil case 0xEC8B: // 8B EC : mov ebp, esp
459*a7c257b0Skamil case 0xc889: // 89 C8 : mov eax, ecx
460*a7c257b0Skamil case 0xC18B: // 8B C1 : mov eax, ecx
461*a7c257b0Skamil case 0xC033: // 33 C0 : xor eax, eax
462*a7c257b0Skamil case 0xC933: // 33 C9 : xor ecx, ecx
463*a7c257b0Skamil case 0xD233: // 33 D2 : xor edx, edx
464*a7c257b0Skamil return 2;
465*a7c257b0Skamil
466*a7c257b0Skamil // Cannot overwrite control-instruction. Return 0 to indicate failure.
467*a7c257b0Skamil case 0x25FF: // FF 25 XX XX XX XX : jmp [XXXXXXXX]
468*a7c257b0Skamil return 0;
469*a7c257b0Skamil }
470*a7c257b0Skamil
471*a7c257b0Skamil switch (0x00FFFFFF & *(u32*)address) {
472*a7c257b0Skamil case 0x24A48D: // 8D A4 24 XX XX XX XX : lea esp, [esp + XX XX XX XX]
473*a7c257b0Skamil return 7;
474*a7c257b0Skamil }
475*a7c257b0Skamil
476*a7c257b0Skamil #if SANITIZER_WINDOWS64
477*a7c257b0Skamil switch (*(u8*)address) {
478*a7c257b0Skamil case 0xA1: // A1 XX XX XX XX XX XX XX XX :
479*a7c257b0Skamil // movabs eax, dword ptr ds:[XXXXXXXX]
480*a7c257b0Skamil return 9;
481*a7c257b0Skamil }
482*a7c257b0Skamil
483*a7c257b0Skamil switch (*(u16*)address) {
484*a7c257b0Skamil case 0x5040: // push rax
485*a7c257b0Skamil case 0x5140: // push rcx
486*a7c257b0Skamil case 0x5240: // push rdx
487*a7c257b0Skamil case 0x5340: // push rbx
488*a7c257b0Skamil case 0x5440: // push rsp
489*a7c257b0Skamil case 0x5540: // push rbp
490*a7c257b0Skamil case 0x5640: // push rsi
491*a7c257b0Skamil case 0x5740: // push rdi
492*a7c257b0Skamil case 0x5441: // push r12
493*a7c257b0Skamil case 0x5541: // push r13
494*a7c257b0Skamil case 0x5641: // push r14
495*a7c257b0Skamil case 0x5741: // push r15
496*a7c257b0Skamil case 0x9066: // Two-byte NOP
497*a7c257b0Skamil return 2;
498*a7c257b0Skamil
499*a7c257b0Skamil case 0x058B: // 8B 05 XX XX XX XX : mov eax, dword ptr [XX XX XX XX]
500*a7c257b0Skamil if (rel_offset)
501*a7c257b0Skamil *rel_offset = 2;
502*a7c257b0Skamil return 6;
503*a7c257b0Skamil }
504*a7c257b0Skamil
505*a7c257b0Skamil switch (0x00FFFFFF & *(u32*)address) {
506*a7c257b0Skamil case 0xe58948: // 48 8b c4 : mov rbp, rsp
507*a7c257b0Skamil case 0xc18b48: // 48 8b c1 : mov rax, rcx
508*a7c257b0Skamil case 0xc48b48: // 48 8b c4 : mov rax, rsp
509*a7c257b0Skamil case 0xd9f748: // 48 f7 d9 : neg rcx
510*a7c257b0Skamil case 0xd12b48: // 48 2b d1 : sub rdx, rcx
511*a7c257b0Skamil case 0x07c1f6: // f6 c1 07 : test cl, 0x7
512*a7c257b0Skamil case 0xc98548: // 48 85 C9 : test rcx, rcx
513*a7c257b0Skamil case 0xc0854d: // 4d 85 c0 : test r8, r8
514*a7c257b0Skamil case 0xc2b60f: // 0f b6 c2 : movzx eax, dl
515*a7c257b0Skamil case 0xc03345: // 45 33 c0 : xor r8d, r8d
516*a7c257b0Skamil case 0xdb3345: // 45 33 DB : xor r11d, r11d
517*a7c257b0Skamil case 0xd98b4c: // 4c 8b d9 : mov r11, rcx
518*a7c257b0Skamil case 0xd28b4c: // 4c 8b d2 : mov r10, rdx
519*a7c257b0Skamil case 0xc98b4c: // 4C 8B C9 : mov r9, rcx
520*a7c257b0Skamil case 0xd2b60f: // 0f b6 d2 : movzx edx, dl
521*a7c257b0Skamil case 0xca2b48: // 48 2b ca : sub rcx, rdx
522*a7c257b0Skamil case 0x10b70f: // 0f b7 10 : movzx edx, WORD PTR [rax]
523*a7c257b0Skamil case 0xc00b4d: // 3d 0b c0 : or r8, r8
524*a7c257b0Skamil case 0xd18b48: // 48 8b d1 : mov rdx, rcx
525*a7c257b0Skamil case 0xdc8b4c: // 4c 8b dc : mov r11, rsp
526*a7c257b0Skamil case 0xd18b4c: // 4c 8b d1 : mov r10, rcx
527*a7c257b0Skamil return 3;
528*a7c257b0Skamil
529*a7c257b0Skamil case 0xec8348: // 48 83 ec XX : sub rsp, XX
530*a7c257b0Skamil case 0xf88349: // 49 83 f8 XX : cmp r8, XX
531*a7c257b0Skamil case 0x588948: // 48 89 58 XX : mov QWORD PTR[rax + XX], rbx
532*a7c257b0Skamil return 4;
533*a7c257b0Skamil
534*a7c257b0Skamil case 0xec8148: // 48 81 EC XX XX XX XX : sub rsp, XXXXXXXX
535*a7c257b0Skamil return 7;
536*a7c257b0Skamil
537*a7c257b0Skamil case 0x058b48: // 48 8b 05 XX XX XX XX :
538*a7c257b0Skamil // mov rax, QWORD PTR [rip + XXXXXXXX]
539*a7c257b0Skamil case 0x25ff48: // 48 ff 25 XX XX XX XX :
540*a7c257b0Skamil // rex.W jmp QWORD PTR [rip + XXXXXXXX]
541*a7c257b0Skamil
542*a7c257b0Skamil // Instructions having offset relative to 'rip' need offset adjustment.
543*a7c257b0Skamil if (rel_offset)
544*a7c257b0Skamil *rel_offset = 3;
545*a7c257b0Skamil return 7;
546*a7c257b0Skamil
547*a7c257b0Skamil case 0x2444c7: // C7 44 24 XX YY YY YY YY
548*a7c257b0Skamil // mov dword ptr [rsp + XX], YYYYYYYY
549*a7c257b0Skamil return 8;
550*a7c257b0Skamil }
551*a7c257b0Skamil
552*a7c257b0Skamil switch (*(u32*)(address)) {
553*a7c257b0Skamil case 0x24448b48: // 48 8b 44 24 XX : mov rax, QWORD ptr [rsp + XX]
554*a7c257b0Skamil case 0x246c8948: // 48 89 6C 24 XX : mov QWORD ptr [rsp + XX], rbp
555*a7c257b0Skamil case 0x245c8948: // 48 89 5c 24 XX : mov QWORD PTR [rsp + XX], rbx
556*a7c257b0Skamil case 0x24748948: // 48 89 74 24 XX : mov QWORD PTR [rsp + XX], rsi
557*a7c257b0Skamil case 0x244C8948: // 48 89 4C 24 XX : mov QWORD PTR [rsp + XX], rcx
558*a7c257b0Skamil return 5;
559*a7c257b0Skamil case 0x24648348: // 48 83 64 24 XX : and QWORD PTR [rsp + XX], YY
560*a7c257b0Skamil return 6;
561*a7c257b0Skamil }
562*a7c257b0Skamil
563*a7c257b0Skamil #else
564*a7c257b0Skamil
565*a7c257b0Skamil switch (*(u8*)address) {
566*a7c257b0Skamil case 0xA1: // A1 XX XX XX XX : mov eax, dword ptr ds:[XXXXXXXX]
567*a7c257b0Skamil return 5;
568*a7c257b0Skamil }
569*a7c257b0Skamil switch (*(u16*)address) {
570*a7c257b0Skamil case 0x458B: // 8B 45 XX : mov eax, dword ptr [ebp + XX]
571*a7c257b0Skamil case 0x5D8B: // 8B 5D XX : mov ebx, dword ptr [ebp + XX]
572*a7c257b0Skamil case 0x7D8B: // 8B 7D XX : mov edi, dword ptr [ebp + XX]
573*a7c257b0Skamil case 0xEC83: // 83 EC XX : sub esp, XX
574*a7c257b0Skamil case 0x75FF: // FF 75 XX : push dword ptr [ebp + XX]
575*a7c257b0Skamil return 3;
576*a7c257b0Skamil case 0xC1F7: // F7 C1 XX YY ZZ WW : test ecx, WWZZYYXX
577*a7c257b0Skamil case 0x25FF: // FF 25 XX YY ZZ WW : jmp dword ptr ds:[WWZZYYXX]
578*a7c257b0Skamil return 6;
579*a7c257b0Skamil case 0x3D83: // 83 3D XX YY ZZ WW TT : cmp TT, WWZZYYXX
580*a7c257b0Skamil return 7;
581*a7c257b0Skamil case 0x7D83: // 83 7D XX YY : cmp dword ptr [ebp + XX], YY
582*a7c257b0Skamil return 4;
583*a7c257b0Skamil }
584*a7c257b0Skamil
585*a7c257b0Skamil switch (0x00FFFFFF & *(u32*)address) {
586*a7c257b0Skamil case 0x24448A: // 8A 44 24 XX : mov eal, dword ptr [esp + XX]
587*a7c257b0Skamil case 0x24448B: // 8B 44 24 XX : mov eax, dword ptr [esp + XX]
588*a7c257b0Skamil case 0x244C8B: // 8B 4C 24 XX : mov ecx, dword ptr [esp + XX]
589*a7c257b0Skamil case 0x24548B: // 8B 54 24 XX : mov edx, dword ptr [esp + XX]
590*a7c257b0Skamil case 0x24748B: // 8B 74 24 XX : mov esi, dword ptr [esp + XX]
591*a7c257b0Skamil case 0x247C8B: // 8B 7C 24 XX : mov edi, dword ptr [esp + XX]
592*a7c257b0Skamil return 4;
593*a7c257b0Skamil }
594*a7c257b0Skamil
595*a7c257b0Skamil switch (*(u32*)address) {
596*a7c257b0Skamil case 0x2444B60F: // 0F B6 44 24 XX : movzx eax, byte ptr [esp + XX]
597*a7c257b0Skamil return 5;
598*a7c257b0Skamil }
599*a7c257b0Skamil #endif
600*a7c257b0Skamil
601*a7c257b0Skamil // Unknown instruction!
602*a7c257b0Skamil // FIXME: Unknown instruction failures might happen when we add a new
603*a7c257b0Skamil // interceptor or a new compiler version. In either case, they should result
604*a7c257b0Skamil // in visible and readable error messages. However, merely calling abort()
605*a7c257b0Skamil // leads to an infinite recursion in CheckFailed.
606*a7c257b0Skamil InterceptionFailed();
607*a7c257b0Skamil return 0;
608*a7c257b0Skamil }
609*a7c257b0Skamil
610*a7c257b0Skamil // Returns 0 on error.
RoundUpToInstrBoundary(size_t size,uptr address)611*a7c257b0Skamil static size_t RoundUpToInstrBoundary(size_t size, uptr address) {
612*a7c257b0Skamil size_t cursor = 0;
613*a7c257b0Skamil while (cursor < size) {
614*a7c257b0Skamil size_t instruction_size = GetInstructionSize(address + cursor);
615*a7c257b0Skamil if (!instruction_size)
616*a7c257b0Skamil return 0;
617*a7c257b0Skamil cursor += instruction_size;
618*a7c257b0Skamil }
619*a7c257b0Skamil return cursor;
620*a7c257b0Skamil }
621*a7c257b0Skamil
CopyInstructions(uptr to,uptr from,size_t size)622*a7c257b0Skamil static bool CopyInstructions(uptr to, uptr from, size_t size) {
623*a7c257b0Skamil size_t cursor = 0;
624*a7c257b0Skamil while (cursor != size) {
625*a7c257b0Skamil size_t rel_offset = 0;
626*a7c257b0Skamil size_t instruction_size = GetInstructionSize(from + cursor, &rel_offset);
627*a7c257b0Skamil _memcpy((void*)(to + cursor), (void*)(from + cursor),
628*a7c257b0Skamil (size_t)instruction_size);
629*a7c257b0Skamil if (rel_offset) {
630*a7c257b0Skamil uptr delta = to - from;
631*a7c257b0Skamil uptr relocated_offset = *(u32*)(to + cursor + rel_offset) - delta;
632*a7c257b0Skamil #if SANITIZER_WINDOWS64
633*a7c257b0Skamil if (relocated_offset + 0x80000000U >= 0xFFFFFFFFU)
634*a7c257b0Skamil return false;
635*a7c257b0Skamil #endif
636*a7c257b0Skamil *(u32*)(to + cursor + rel_offset) = relocated_offset;
637*a7c257b0Skamil }
638*a7c257b0Skamil cursor += instruction_size;
639*a7c257b0Skamil }
640*a7c257b0Skamil return true;
641*a7c257b0Skamil }
642*a7c257b0Skamil
643*a7c257b0Skamil
644*a7c257b0Skamil #if !SANITIZER_WINDOWS64
OverrideFunctionWithDetour(uptr old_func,uptr new_func,uptr * orig_old_func)645*a7c257b0Skamil bool OverrideFunctionWithDetour(
646*a7c257b0Skamil uptr old_func, uptr new_func, uptr *orig_old_func) {
647*a7c257b0Skamil const int kDetourHeaderLen = 5;
648*a7c257b0Skamil const u16 kDetourInstruction = 0xFF8B;
649*a7c257b0Skamil
650*a7c257b0Skamil uptr header = (uptr)old_func - kDetourHeaderLen;
651*a7c257b0Skamil uptr patch_length = kDetourHeaderLen + kShortJumpInstructionLength;
652*a7c257b0Skamil
653*a7c257b0Skamil // Validate that the function is hookable.
654*a7c257b0Skamil if (*(u16*)old_func != kDetourInstruction ||
655*a7c257b0Skamil !IsMemoryPadding(header, kDetourHeaderLen))
656*a7c257b0Skamil return false;
657*a7c257b0Skamil
658*a7c257b0Skamil // Change memory protection to writable.
659*a7c257b0Skamil DWORD protection = 0;
660*a7c257b0Skamil if (!ChangeMemoryProtection(header, patch_length, &protection))
661*a7c257b0Skamil return false;
662*a7c257b0Skamil
663*a7c257b0Skamil // Write a relative jump to the redirected function.
664*a7c257b0Skamil WriteJumpInstruction(header, new_func);
665*a7c257b0Skamil
666*a7c257b0Skamil // Write the short jump to the function prefix.
667*a7c257b0Skamil WriteShortJumpInstruction(old_func, header);
668*a7c257b0Skamil
669*a7c257b0Skamil // Restore previous memory protection.
670*a7c257b0Skamil if (!RestoreMemoryProtection(header, patch_length, protection))
671*a7c257b0Skamil return false;
672*a7c257b0Skamil
673*a7c257b0Skamil if (orig_old_func)
674*a7c257b0Skamil *orig_old_func = old_func + kShortJumpInstructionLength;
675*a7c257b0Skamil
676*a7c257b0Skamil return true;
677*a7c257b0Skamil }
678*a7c257b0Skamil #endif
679*a7c257b0Skamil
OverrideFunctionWithRedirectJump(uptr old_func,uptr new_func,uptr * orig_old_func)680*a7c257b0Skamil bool OverrideFunctionWithRedirectJump(
681*a7c257b0Skamil uptr old_func, uptr new_func, uptr *orig_old_func) {
682*a7c257b0Skamil // Check whether the first instruction is a relative jump.
683*a7c257b0Skamil if (*(u8*)old_func != 0xE9)
684*a7c257b0Skamil return false;
685*a7c257b0Skamil
686*a7c257b0Skamil if (orig_old_func) {
687*a7c257b0Skamil uptr relative_offset = *(u32*)(old_func + 1);
688*a7c257b0Skamil uptr absolute_target = old_func + relative_offset + kJumpInstructionLength;
689*a7c257b0Skamil *orig_old_func = absolute_target;
690*a7c257b0Skamil }
691*a7c257b0Skamil
692*a7c257b0Skamil #if SANITIZER_WINDOWS64
693*a7c257b0Skamil // If needed, get memory space for a trampoline jump.
694*a7c257b0Skamil uptr trampoline = AllocateMemoryForTrampoline(old_func, kDirectBranchLength);
695*a7c257b0Skamil if (!trampoline)
696*a7c257b0Skamil return false;
697*a7c257b0Skamil WriteDirectBranch(trampoline, new_func);
698*a7c257b0Skamil #endif
699*a7c257b0Skamil
700*a7c257b0Skamil // Change memory protection to writable.
701*a7c257b0Skamil DWORD protection = 0;
702*a7c257b0Skamil if (!ChangeMemoryProtection(old_func, kJumpInstructionLength, &protection))
703*a7c257b0Skamil return false;
704*a7c257b0Skamil
705*a7c257b0Skamil // Write a relative jump to the redirected function.
706*a7c257b0Skamil WriteJumpInstruction(old_func, FIRST_32_SECOND_64(new_func, trampoline));
707*a7c257b0Skamil
708*a7c257b0Skamil // Restore previous memory protection.
709*a7c257b0Skamil if (!RestoreMemoryProtection(old_func, kJumpInstructionLength, protection))
710*a7c257b0Skamil return false;
711*a7c257b0Skamil
712*a7c257b0Skamil return true;
713*a7c257b0Skamil }
714*a7c257b0Skamil
OverrideFunctionWithHotPatch(uptr old_func,uptr new_func,uptr * orig_old_func)715*a7c257b0Skamil bool OverrideFunctionWithHotPatch(
716*a7c257b0Skamil uptr old_func, uptr new_func, uptr *orig_old_func) {
717*a7c257b0Skamil const int kHotPatchHeaderLen = kBranchLength;
718*a7c257b0Skamil
719*a7c257b0Skamil uptr header = (uptr)old_func - kHotPatchHeaderLen;
720*a7c257b0Skamil uptr patch_length = kHotPatchHeaderLen + kShortJumpInstructionLength;
721*a7c257b0Skamil
722*a7c257b0Skamil // Validate that the function is hot patchable.
723*a7c257b0Skamil size_t instruction_size = GetInstructionSize(old_func);
724*a7c257b0Skamil if (instruction_size < kShortJumpInstructionLength ||
725*a7c257b0Skamil !FunctionHasPadding(old_func, kHotPatchHeaderLen))
726*a7c257b0Skamil return false;
727*a7c257b0Skamil
728*a7c257b0Skamil if (orig_old_func) {
729*a7c257b0Skamil // Put the needed instructions into the trampoline bytes.
730*a7c257b0Skamil uptr trampoline_length = instruction_size + kDirectBranchLength;
731*a7c257b0Skamil uptr trampoline = AllocateMemoryForTrampoline(old_func, trampoline_length);
732*a7c257b0Skamil if (!trampoline)
733*a7c257b0Skamil return false;
734*a7c257b0Skamil if (!CopyInstructions(trampoline, old_func, instruction_size))
735*a7c257b0Skamil return false;
736*a7c257b0Skamil WriteDirectBranch(trampoline + instruction_size,
737*a7c257b0Skamil old_func + instruction_size);
738*a7c257b0Skamil *orig_old_func = trampoline;
739*a7c257b0Skamil }
740*a7c257b0Skamil
741*a7c257b0Skamil // If needed, get memory space for indirect address.
742*a7c257b0Skamil uptr indirect_address = 0;
743*a7c257b0Skamil #if SANITIZER_WINDOWS64
744*a7c257b0Skamil indirect_address = AllocateMemoryForTrampoline(old_func, kAddressLength);
745*a7c257b0Skamil if (!indirect_address)
746*a7c257b0Skamil return false;
747*a7c257b0Skamil #endif
748*a7c257b0Skamil
749*a7c257b0Skamil // Change memory protection to writable.
750*a7c257b0Skamil DWORD protection = 0;
751*a7c257b0Skamil if (!ChangeMemoryProtection(header, patch_length, &protection))
752*a7c257b0Skamil return false;
753*a7c257b0Skamil
754*a7c257b0Skamil // Write jumps to the redirected function.
755*a7c257b0Skamil WriteBranch(header, indirect_address, new_func);
756*a7c257b0Skamil WriteShortJumpInstruction(old_func, header);
757*a7c257b0Skamil
758*a7c257b0Skamil // Restore previous memory protection.
759*a7c257b0Skamil if (!RestoreMemoryProtection(header, patch_length, protection))
760*a7c257b0Skamil return false;
761*a7c257b0Skamil
762*a7c257b0Skamil return true;
763*a7c257b0Skamil }
764*a7c257b0Skamil
OverrideFunctionWithTrampoline(uptr old_func,uptr new_func,uptr * orig_old_func)765*a7c257b0Skamil bool OverrideFunctionWithTrampoline(
766*a7c257b0Skamil uptr old_func, uptr new_func, uptr *orig_old_func) {
767*a7c257b0Skamil
768*a7c257b0Skamil size_t instructions_length = kBranchLength;
769*a7c257b0Skamil size_t padding_length = 0;
770*a7c257b0Skamil uptr indirect_address = 0;
771*a7c257b0Skamil
772*a7c257b0Skamil if (orig_old_func) {
773*a7c257b0Skamil // Find out the number of bytes of the instructions we need to copy
774*a7c257b0Skamil // to the trampoline.
775*a7c257b0Skamil instructions_length = RoundUpToInstrBoundary(kBranchLength, old_func);
776*a7c257b0Skamil if (!instructions_length)
777*a7c257b0Skamil return false;
778*a7c257b0Skamil
779*a7c257b0Skamil // Put the needed instructions into the trampoline bytes.
780*a7c257b0Skamil uptr trampoline_length = instructions_length + kDirectBranchLength;
781*a7c257b0Skamil uptr trampoline = AllocateMemoryForTrampoline(old_func, trampoline_length);
782*a7c257b0Skamil if (!trampoline)
783*a7c257b0Skamil return false;
784*a7c257b0Skamil if (!CopyInstructions(trampoline, old_func, instructions_length))
785*a7c257b0Skamil return false;
786*a7c257b0Skamil WriteDirectBranch(trampoline + instructions_length,
787*a7c257b0Skamil old_func + instructions_length);
788*a7c257b0Skamil *orig_old_func = trampoline;
789*a7c257b0Skamil }
790*a7c257b0Skamil
791*a7c257b0Skamil #if SANITIZER_WINDOWS64
792*a7c257b0Skamil // Check if the targeted address can be encoded in the function padding.
793*a7c257b0Skamil // Otherwise, allocate it in the trampoline region.
794*a7c257b0Skamil if (IsMemoryPadding(old_func - kAddressLength, kAddressLength)) {
795*a7c257b0Skamil indirect_address = old_func - kAddressLength;
796*a7c257b0Skamil padding_length = kAddressLength;
797*a7c257b0Skamil } else {
798*a7c257b0Skamil indirect_address = AllocateMemoryForTrampoline(old_func, kAddressLength);
799*a7c257b0Skamil if (!indirect_address)
800*a7c257b0Skamil return false;
801*a7c257b0Skamil }
802*a7c257b0Skamil #endif
803*a7c257b0Skamil
804*a7c257b0Skamil // Change memory protection to writable.
805*a7c257b0Skamil uptr patch_address = old_func - padding_length;
806*a7c257b0Skamil uptr patch_length = instructions_length + padding_length;
807*a7c257b0Skamil DWORD protection = 0;
808*a7c257b0Skamil if (!ChangeMemoryProtection(patch_address, patch_length, &protection))
809*a7c257b0Skamil return false;
810*a7c257b0Skamil
811*a7c257b0Skamil // Patch the original function.
812*a7c257b0Skamil WriteBranch(old_func, indirect_address, new_func);
813*a7c257b0Skamil
814*a7c257b0Skamil // Restore previous memory protection.
815*a7c257b0Skamil if (!RestoreMemoryProtection(patch_address, patch_length, protection))
816*a7c257b0Skamil return false;
817*a7c257b0Skamil
818*a7c257b0Skamil return true;
819*a7c257b0Skamil }
820*a7c257b0Skamil
OverrideFunction(uptr old_func,uptr new_func,uptr * orig_old_func)821*a7c257b0Skamil bool OverrideFunction(
822*a7c257b0Skamil uptr old_func, uptr new_func, uptr *orig_old_func) {
823*a7c257b0Skamil #if !SANITIZER_WINDOWS64
824*a7c257b0Skamil if (OverrideFunctionWithDetour(old_func, new_func, orig_old_func))
825*a7c257b0Skamil return true;
826*a7c257b0Skamil #endif
827*a7c257b0Skamil if (OverrideFunctionWithRedirectJump(old_func, new_func, orig_old_func))
828*a7c257b0Skamil return true;
829*a7c257b0Skamil if (OverrideFunctionWithHotPatch(old_func, new_func, orig_old_func))
830*a7c257b0Skamil return true;
831*a7c257b0Skamil if (OverrideFunctionWithTrampoline(old_func, new_func, orig_old_func))
832*a7c257b0Skamil return true;
833*a7c257b0Skamil return false;
834*a7c257b0Skamil }
835*a7c257b0Skamil
InterestingDLLsAvailable()836*a7c257b0Skamil static void **InterestingDLLsAvailable() {
837*a7c257b0Skamil static const char *InterestingDLLs[] = {
838*a7c257b0Skamil "kernel32.dll",
839*a7c257b0Skamil "msvcr100.dll", // VS2010
840*a7c257b0Skamil "msvcr110.dll", // VS2012
841*a7c257b0Skamil "msvcr120.dll", // VS2013
842*a7c257b0Skamil "vcruntime140.dll", // VS2015
843*a7c257b0Skamil "ucrtbase.dll", // Universal CRT
844*a7c257b0Skamil // NTDLL should go last as it exports some functions that we should
845*a7c257b0Skamil // override in the CRT [presumably only used internally].
846*a7c257b0Skamil "ntdll.dll", NULL};
847*a7c257b0Skamil static void *result[ARRAY_SIZE(InterestingDLLs)] = { 0 };
848*a7c257b0Skamil if (!result[0]) {
849*a7c257b0Skamil for (size_t i = 0, j = 0; InterestingDLLs[i]; ++i) {
850*a7c257b0Skamil if (HMODULE h = GetModuleHandleA(InterestingDLLs[i]))
851*a7c257b0Skamil result[j++] = (void *)h;
852*a7c257b0Skamil }
853*a7c257b0Skamil }
854*a7c257b0Skamil return &result[0];
855*a7c257b0Skamil }
856*a7c257b0Skamil
857*a7c257b0Skamil namespace {
858*a7c257b0Skamil // Utility for reading loaded PE images.
859*a7c257b0Skamil template <typename T> class RVAPtr {
860*a7c257b0Skamil public:
RVAPtr(void * module,uptr rva)861*a7c257b0Skamil RVAPtr(void *module, uptr rva)
862*a7c257b0Skamil : ptr_(reinterpret_cast<T *>(reinterpret_cast<char *>(module) + rva)) {}
operator T*()863*a7c257b0Skamil operator T *() { return ptr_; }
operator ->()864*a7c257b0Skamil T *operator->() { return ptr_; }
operator ++()865*a7c257b0Skamil T *operator++() { return ++ptr_; }
866*a7c257b0Skamil
867*a7c257b0Skamil private:
868*a7c257b0Skamil T *ptr_;
869*a7c257b0Skamil };
870*a7c257b0Skamil } // namespace
871*a7c257b0Skamil
872*a7c257b0Skamil // Internal implementation of GetProcAddress. At least since Windows 8,
873*a7c257b0Skamil // GetProcAddress appears to initialize DLLs before returning function pointers
874*a7c257b0Skamil // into them. This is problematic for the sanitizers, because they typically
875*a7c257b0Skamil // want to intercept malloc *before* MSVCRT initializes. Our internal
876*a7c257b0Skamil // implementation walks the export list manually without doing initialization.
InternalGetProcAddress(void * module,const char * func_name)877*a7c257b0Skamil uptr InternalGetProcAddress(void *module, const char *func_name) {
878*a7c257b0Skamil // Check that the module header is full and present.
879*a7c257b0Skamil RVAPtr<IMAGE_DOS_HEADER> dos_stub(module, 0);
880*a7c257b0Skamil RVAPtr<IMAGE_NT_HEADERS> headers(module, dos_stub->e_lfanew);
881*a7c257b0Skamil if (!module || dos_stub->e_magic != IMAGE_DOS_SIGNATURE || // "MZ"
882*a7c257b0Skamil headers->Signature != IMAGE_NT_SIGNATURE || // "PE\0\0"
883*a7c257b0Skamil headers->FileHeader.SizeOfOptionalHeader <
884*a7c257b0Skamil sizeof(IMAGE_OPTIONAL_HEADER)) {
885*a7c257b0Skamil return 0;
886*a7c257b0Skamil }
887*a7c257b0Skamil
888*a7c257b0Skamil IMAGE_DATA_DIRECTORY *export_directory =
889*a7c257b0Skamil &headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT];
890*a7c257b0Skamil if (export_directory->Size == 0)
891*a7c257b0Skamil return 0;
892*a7c257b0Skamil RVAPtr<IMAGE_EXPORT_DIRECTORY> exports(module,
893*a7c257b0Skamil export_directory->VirtualAddress);
894*a7c257b0Skamil RVAPtr<DWORD> functions(module, exports->AddressOfFunctions);
895*a7c257b0Skamil RVAPtr<DWORD> names(module, exports->AddressOfNames);
896*a7c257b0Skamil RVAPtr<WORD> ordinals(module, exports->AddressOfNameOrdinals);
897*a7c257b0Skamil
898*a7c257b0Skamil for (DWORD i = 0; i < exports->NumberOfNames; i++) {
899*a7c257b0Skamil RVAPtr<char> name(module, names[i]);
900*a7c257b0Skamil if (!strcmp(func_name, name)) {
901*a7c257b0Skamil DWORD index = ordinals[i];
902*a7c257b0Skamil RVAPtr<char> func(module, functions[index]);
903*a7c257b0Skamil
904*a7c257b0Skamil // Handle forwarded functions.
905*a7c257b0Skamil DWORD offset = functions[index];
906*a7c257b0Skamil if (offset >= export_directory->VirtualAddress &&
907*a7c257b0Skamil offset < export_directory->VirtualAddress + export_directory->Size) {
908*a7c257b0Skamil // An entry for a forwarded function is a string with the following
909*a7c257b0Skamil // format: "<module> . <function_name>" that is stored into the
910*a7c257b0Skamil // exported directory.
911*a7c257b0Skamil char function_name[256];
912*a7c257b0Skamil size_t funtion_name_length = _strlen(func);
913*a7c257b0Skamil if (funtion_name_length >= sizeof(function_name) - 1)
914*a7c257b0Skamil InterceptionFailed();
915*a7c257b0Skamil
916*a7c257b0Skamil _memcpy(function_name, func, funtion_name_length);
917*a7c257b0Skamil function_name[funtion_name_length] = '\0';
918*a7c257b0Skamil char* separator = _strchr(function_name, '.');
919*a7c257b0Skamil if (!separator)
920*a7c257b0Skamil InterceptionFailed();
921*a7c257b0Skamil *separator = '\0';
922*a7c257b0Skamil
923*a7c257b0Skamil void* redirected_module = GetModuleHandleA(function_name);
924*a7c257b0Skamil if (!redirected_module)
925*a7c257b0Skamil InterceptionFailed();
926*a7c257b0Skamil return InternalGetProcAddress(redirected_module, separator + 1);
927*a7c257b0Skamil }
928*a7c257b0Skamil
929*a7c257b0Skamil return (uptr)(char *)func;
930*a7c257b0Skamil }
931*a7c257b0Skamil }
932*a7c257b0Skamil
933*a7c257b0Skamil return 0;
934*a7c257b0Skamil }
935*a7c257b0Skamil
OverrideFunction(const char * func_name,uptr new_func,uptr * orig_old_func)936*a7c257b0Skamil bool OverrideFunction(
937*a7c257b0Skamil const char *func_name, uptr new_func, uptr *orig_old_func) {
938*a7c257b0Skamil bool hooked = false;
939*a7c257b0Skamil void **DLLs = InterestingDLLsAvailable();
940*a7c257b0Skamil for (size_t i = 0; DLLs[i]; ++i) {
941*a7c257b0Skamil uptr func_addr = InternalGetProcAddress(DLLs[i], func_name);
942*a7c257b0Skamil if (func_addr &&
943*a7c257b0Skamil OverrideFunction(func_addr, new_func, orig_old_func)) {
944*a7c257b0Skamil hooked = true;
945*a7c257b0Skamil }
946*a7c257b0Skamil }
947*a7c257b0Skamil return hooked;
948*a7c257b0Skamil }
949*a7c257b0Skamil
OverrideImportedFunction(const char * module_to_patch,const char * imported_module,const char * function_name,uptr new_function,uptr * orig_old_func)950*a7c257b0Skamil bool OverrideImportedFunction(const char *module_to_patch,
951*a7c257b0Skamil const char *imported_module,
952*a7c257b0Skamil const char *function_name, uptr new_function,
953*a7c257b0Skamil uptr *orig_old_func) {
954*a7c257b0Skamil HMODULE module = GetModuleHandleA(module_to_patch);
955*a7c257b0Skamil if (!module)
956*a7c257b0Skamil return false;
957*a7c257b0Skamil
958*a7c257b0Skamil // Check that the module header is full and present.
959*a7c257b0Skamil RVAPtr<IMAGE_DOS_HEADER> dos_stub(module, 0);
960*a7c257b0Skamil RVAPtr<IMAGE_NT_HEADERS> headers(module, dos_stub->e_lfanew);
961*a7c257b0Skamil if (!module || dos_stub->e_magic != IMAGE_DOS_SIGNATURE || // "MZ"
962*a7c257b0Skamil headers->Signature != IMAGE_NT_SIGNATURE || // "PE\0\0"
963*a7c257b0Skamil headers->FileHeader.SizeOfOptionalHeader <
964*a7c257b0Skamil sizeof(IMAGE_OPTIONAL_HEADER)) {
965*a7c257b0Skamil return false;
966*a7c257b0Skamil }
967*a7c257b0Skamil
968*a7c257b0Skamil IMAGE_DATA_DIRECTORY *import_directory =
969*a7c257b0Skamil &headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT];
970*a7c257b0Skamil
971*a7c257b0Skamil // Iterate the list of imported DLLs. FirstThunk will be null for the last
972*a7c257b0Skamil // entry.
973*a7c257b0Skamil RVAPtr<IMAGE_IMPORT_DESCRIPTOR> imports(module,
974*a7c257b0Skamil import_directory->VirtualAddress);
975*a7c257b0Skamil for (; imports->FirstThunk != 0; ++imports) {
976*a7c257b0Skamil RVAPtr<const char> modname(module, imports->Name);
977*a7c257b0Skamil if (_stricmp(&*modname, imported_module) == 0)
978*a7c257b0Skamil break;
979*a7c257b0Skamil }
980*a7c257b0Skamil if (imports->FirstThunk == 0)
981*a7c257b0Skamil return false;
982*a7c257b0Skamil
983*a7c257b0Skamil // We have two parallel arrays: the import address table (IAT) and the table
984*a7c257b0Skamil // of names. They start out containing the same data, but the loader rewrites
985*a7c257b0Skamil // the IAT to hold imported addresses and leaves the name table in
986*a7c257b0Skamil // OriginalFirstThunk alone.
987*a7c257b0Skamil RVAPtr<IMAGE_THUNK_DATA> name_table(module, imports->OriginalFirstThunk);
988*a7c257b0Skamil RVAPtr<IMAGE_THUNK_DATA> iat(module, imports->FirstThunk);
989*a7c257b0Skamil for (; name_table->u1.Ordinal != 0; ++name_table, ++iat) {
990*a7c257b0Skamil if (!IMAGE_SNAP_BY_ORDINAL(name_table->u1.Ordinal)) {
991*a7c257b0Skamil RVAPtr<IMAGE_IMPORT_BY_NAME> import_by_name(
992*a7c257b0Skamil module, name_table->u1.ForwarderString);
993*a7c257b0Skamil const char *funcname = &import_by_name->Name[0];
994*a7c257b0Skamil if (strcmp(funcname, function_name) == 0)
995*a7c257b0Skamil break;
996*a7c257b0Skamil }
997*a7c257b0Skamil }
998*a7c257b0Skamil if (name_table->u1.Ordinal == 0)
999*a7c257b0Skamil return false;
1000*a7c257b0Skamil
1001*a7c257b0Skamil // Now we have the correct IAT entry. Do the swap. We have to make the page
1002*a7c257b0Skamil // read/write first.
1003*a7c257b0Skamil if (orig_old_func)
1004*a7c257b0Skamil *orig_old_func = iat->u1.AddressOfData;
1005*a7c257b0Skamil DWORD old_prot, unused_prot;
1006*a7c257b0Skamil if (!VirtualProtect(&iat->u1.AddressOfData, 4, PAGE_EXECUTE_READWRITE,
1007*a7c257b0Skamil &old_prot))
1008*a7c257b0Skamil return false;
1009*a7c257b0Skamil iat->u1.AddressOfData = new_function;
1010*a7c257b0Skamil if (!VirtualProtect(&iat->u1.AddressOfData, 4, old_prot, &unused_prot))
1011*a7c257b0Skamil return false; // Not clear if this failure bothers us.
1012*a7c257b0Skamil return true;
1013*a7c257b0Skamil }
1014*a7c257b0Skamil
1015*a7c257b0Skamil } // namespace __interception
1016*a7c257b0Skamil
1017*a7c257b0Skamil #endif // SANITIZER_MAC
1018