//===-- interception_linux.cc -----------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of AddressSanitizer, an address sanity checker.
//
// Windows-specific interception methods.
//
// This file is implementing several hooking techniques to intercept calls
// to functions. The hooks are dynamically installed by modifying the assembly
// code.
//
// The hooking techniques are making assumptions on the way the code is
// generated and are safe under these assumptions.
//
// On 64-bit architecture, there is no direct 64-bit jump instruction. To allow
// arbitrary branching on the whole memory space, the notion of trampoline
// region is used. A trampoline region is a memory space withing 2G boundary
// where it is safe to add custom assembly code to build 64-bit jumps.
//
// Hooking techniques
// ==================
//
// 1) Detour
//
// The Detour hooking technique is assuming the presence of an header with
// padding and an overridable 2-bytes nop instruction (mov edi, edi). The
// nop instruction can safely be replaced by a 2-bytes jump without any need
// to save the instruction. A jump to the target is encoded in the function
// header and the nop instruction is replaced by a short jump to the header.
//
// head: 5 x nop head: jmp <hook>
// func: mov edi, edi --> func: jmp short <head>
// [...] real: [...]
//
// This technique is only implemented on 32-bit architecture.
// Most of the time, Windows API are hookable with the detour technique.
//
// 2) Redirect Jump
//
// The redirect jump is applicable when the first instruction is a direct
// jump. The instruction is replaced by jump to the hook.
//
// func: jmp <label> --> func: jmp <hook>
//
// On an 64-bit architecture, a trampoline is inserted.
//
// func: jmp <label> --> func: jmp <tramp>
// [...]
//
// [trampoline]
// tramp: jmp QWORD [addr]
// addr: .bytes <hook>
//
// Note: <real> is equilavent to <label>.
//
// 3) HotPatch
//
// The HotPatch hooking is assuming the presence of an header with padding
// and a first instruction with at least 2-bytes.
//
// The reason to enforce the 2-bytes limitation is to provide the minimal
// space to encode a short jump. HotPatch technique is only rewriting one
// instruction to avoid breaking a sequence of instructions containing a
// branching target.
//
// Assumptions are enforced by MSVC compiler by using the /HOTPATCH flag.
// see: https://msdn.microsoft.com/en-us/library/ms173507.aspx
// Default padding length is 5 bytes in 32-bits and 6 bytes in 64-bits.
//
// head: 5 x nop head: jmp <hook>
// func: <instr> --> func: jmp short <head>
// [...] body: [...]
//
// [trampoline]
// real: <instr>
// jmp <body>
//
// On an 64-bit architecture:
//
// head: 6 x nop head: jmp QWORD [addr1]
// func: <instr> --> func: jmp short <head>
// [...] body: [...]
//
// [trampoline]
// addr1: .bytes <hook>
// real: <instr>
// jmp QWORD [addr2]
// addr2: .bytes <body>
//
// 4) Trampoline
//
// The Trampoline hooking technique is the most aggressive one. It is
// assuming that there is a sequence of instructions that can be safely
// replaced by a jump (enough room and no incoming branches).
//
// Unfortunately, these assumptions can't be safely presumed and code may
// be broken after hooking.
//
// func: <instr> --> func: jmp <hook>
// <instr>
// [...] body: [...]
//
// [trampoline]
// real: <instr>
// <instr>
// jmp <body>
//
// On an 64-bit architecture:
//
// func: <instr> --> func: jmp QWORD [addr1]
// <instr>
// [...] body: [...]
//
// [trampoline]
// addr1: .bytes <hook>
// real: <instr>
// <instr>
// jmp QWORD [addr2]
// addr2: .bytes <body>
//===----------------------------------------------------------------------===//
#ifdef _WIN32
#include "interception.h"
#include "sanitizer_common/sanitizer_platform.h"
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
namespace __interception {
static const int kAddressLength = FIRST_32_SECOND_64(4, 8);
static const int kJumpInstructionLength = 5;
static const int kShortJumpInstructionLength = 2;
static const int kIndirectJumpInstructionLength = 6;
static const int kBranchLength =
FIRST_32_SECOND_64(kJumpInstructionLength, kIndirectJumpInstructionLength);
static const int kDirectBranchLength = kBranchLength + kAddressLength;
static void InterceptionFailed() {
// Do we have a good way to abort with an error message here?
__debugbreak();
}
static bool DistanceIsWithin2Gig(uptr from, uptr target) {
if (from < target)
return target - from <= (uptr)0x7FFFFFFFU;
else
return from - target <= (uptr)0x80000000U;
}
static uptr GetMmapGranularity() {
SYSTEM_INFO si;
GetSystemInfo(&si);
return si.dwAllocationGranularity;
}
static uptr RoundUpTo(uptr size, uptr boundary) {
return (size + boundary - 1) & ~(boundary - 1);
}
// FIXME: internal_str* and internal_mem* functions should be moved from the
// ASan sources into interception/.
static void _memset(void *p, int value, size_t sz) {
for (size_t i = 0; i < sz; ++i)
((char*)p)[i] = (char)value;
}
static void _memcpy(void *dst, void *src, size_t sz) {
char *dst_c = (char*)dst,
*src_c = (char*)src;
for (size_t i = 0; i < sz; ++i)
dst_c[i] = src_c[i];
}
static bool ChangeMemoryProtection(
uptr address, uptr size, DWORD *old_protection) {
return ::VirtualProtect((void*)address, size,
PAGE_EXECUTE_READWRITE,
old_protection) != FALSE;
}
static bool RestoreMemoryProtection(
uptr address, uptr size, DWORD old_protection) {
DWORD unused;
return ::VirtualProtect((void*)address, size,
old_protection,
&unused) != FALSE;
}
static bool IsMemoryPadding(uptr address, uptr size) {
u8* function = (u8*)address;
for (size_t i = 0; i < size; ++i)
if (function[i] != 0x90 && function[i] != 0xCC)
return false;
return true;
}
static const u8 kHintNop10Bytes[] = {
0x66, 0x66, 0x0F, 0x1F, 0x84,
0x00, 0x00, 0x00, 0x00, 0x00
};
template<class T>
static bool FunctionHasPrefix(uptr address, const T &pattern) {
u8* function = (u8*)address - sizeof(pattern);
for (size_t i = 0; i < sizeof(pattern); ++i)
if (function[i] != pattern[i])
return false;
return true;
}
static bool FunctionHasPadding(uptr address, uptr size) {
if (IsMemoryPadding(address - size, size))
return true;
if (size <= sizeof(kHintNop10Bytes) &&
FunctionHasPrefix(address, kHintNop10Bytes))
return true;
return false;
}
static void WritePadding(uptr from, uptr size) {
_memset((void*)from, 0xCC, (size_t)size);
}
static void CopyInstructions(uptr from, uptr to, uptr size) {
_memcpy((void*)from, (void*)to, (size_t)size);
}
static void WriteJumpInstruction(uptr from, uptr target) {
if (!DistanceIsWithin2Gig(from + kJumpInstructionLength, target))
InterceptionFailed();
ptrdiff_t offset = target - from - kJumpInstructionLength;
*(u8*)from = 0xE9;
*(u32*)(from + 1) = offset;
}
static void WriteShortJumpInstruction(uptr from, uptr target) {
sptr offset = target - from - kShortJumpInstructionLength;
if (offset < -128 || offset > 127)
InterceptionFailed();
*(u8*)from = 0xEB;
*(u8*)(from + 1) = (u8)offset;
}
#if SANITIZER_WINDOWS64
static void WriteIndirectJumpInstruction(uptr from, uptr indirect_target) {
// jmp [rip + <offset>] = FF 25 <offset> where <offset> is a relative
// offset.
// The offset is the distance from then end of the jump instruction to the
// memory location containing the targeted address. The displacement is still
// 32-bit in x64, so indirect_target must be located within +/- 2GB range.
int offset = indirect_target - from - kIndirectJumpInstructionLength;
if (!DistanceIsWithin2Gig(from + kIndirectJumpInstructionLength,
indirect_target)) {
InterceptionFailed();
}
*(u16*)from = 0x25FF;
*(u32*)(from + 2) = offset;
}
#endif
static void WriteBranch(
uptr from, uptr indirect_target, uptr target) {
#if SANITIZER_WINDOWS64
WriteIndirectJumpInstruction(from, indirect_target);
*(u64*)indirect_target = target;
#else
(void)indirect_target;
WriteJumpInstruction(from, target);
#endif
}
static void WriteDirectBranch(uptr from, uptr target) {
#if SANITIZER_WINDOWS64
// Emit an indirect jump through immediately following bytes:
// jmp [rip + kBranchLength]
// .quad <target>
WriteBranch(from, from + kBranchLength, target);
#else
WriteJumpInstruction(from, target);
#endif
}
struct TrampolineMemoryRegion {
uptr content;
uptr allocated_size;
uptr max_size;
};
static const uptr kTrampolineScanLimitRange = 1 << 30; // 1 gig
static const int kMaxTrampolineRegion = 1024;
static TrampolineMemoryRegion TrampolineRegions[kMaxTrampolineRegion];
static void *AllocateTrampolineRegion(uptr image_address, size_t granularity) {
#if SANITIZER_WINDOWS64
uptr address = image_address;
uptr scanned = 0;
while (scanned < kTrampolineScanLimitRange) {
MEMORY_BASIC_INFORMATION info;
if (!::VirtualQuery((void*)address, &info, sizeof(info)))
return nullptr;
// Check whether a region can be allocated at |address|.
if (info.State == MEM_FREE && info.RegionSize >= granularity) {
void *page = ::VirtualAlloc((void*)RoundUpTo(address, granularity),
granularity,
MEM_RESERVE | MEM_COMMIT,
PAGE_EXECUTE_READWRITE);
return page;
}
// Move to the next region.
address = (uptr)info.BaseAddress + info.RegionSize;
scanned += info.RegionSize;
}
return nullptr;
#else
return ::VirtualAlloc(nullptr,
granularity,
MEM_RESERVE | MEM_COMMIT,
PAGE_EXECUTE_READWRITE);
#endif
}
// Used by unittests to release mapped memory space.
void TestOnlyReleaseTrampolineRegions() {
for (size_t bucket = 0; bucket < kMaxTrampolineRegion; ++bucket) {
TrampolineMemoryRegion *current = &TrampolineRegions[bucket];
if (current->content == 0)
return;
::VirtualFree((void*)current->content, 0, MEM_RELEASE);
current->content = 0;
}
}
static uptr AllocateMemoryForTrampoline(uptr image_address, size_t size) {
// Find a region within 2G with enough space to allocate |size| bytes.
TrampolineMemoryRegion *region = nullptr;
for (size_t bucket = 0; bucket < kMaxTrampolineRegion; ++bucket) {
TrampolineMemoryRegion* current = &TrampolineRegions[bucket];
if (current->content == 0) {
// No valid region found, allocate a new region.
size_t bucket_size = GetMmapGranularity();
void *content = AllocateTrampolineRegion(image_address, bucket_size);
if (content == nullptr)
return 0U;
current->content = (uptr)content;
current->allocated_size = 0;
current->max_size = bucket_size;
region = current;
break;
} else if (current->max_size - current->allocated_size > size) {
#if SANITIZER_WINDOWS64
// In 64-bits, the memory space must be allocated within 2G boundary.
uptr next_address = current->content + current->allocated_size;
if (next_address < image_address ||
next_address - image_address >= 0x7FFF0000)
continue;
#endif
// The space can be allocated in the current region.
region = current;
break;
}
}
// Failed to find a region.
if (region == nullptr)
return 0U;
// Allocate the space in the current region.
uptr allocated_space = region->content + region->allocated_size;
region->allocated_size += size;
WritePadding(allocated_space, size);
return allocated_space;
}
// Returns 0 on error.
static size_t GetInstructionSize(uptr address) {
switch (*(u8*)address) {
case 0x90: // 90 : nop
return 1;
case 0x50: // push eax / rax
case 0x51: // push ecx / rcx
case 0x52: // push edx / rdx
case 0x53: // push ebx / rbx
case 0x54: // push esp / rsp
case 0x55: // push ebp / rbp
case 0x56: // push esi / rsi
case 0x57: // push edi / rdi
case 0x5D: // pop ebp / rbp
return 1;
case 0x6A: // 6A XX = push XX
return 2;
case 0xb8: // b8 XX XX XX XX : mov eax, XX XX XX XX
case 0xB9: // b9 XX XX XX XX : mov ecx, XX XX XX XX
case 0xA1: // A1 XX XX XX XX : mov eax, dword ptr ds:[XXXXXXXX]
return 5;
// Cannot overwrite control-instruction. Return 0 to indicate failure.
case 0xE9: // E9 XX XX XX XX : jmp <label>
case 0xE8: // E8 XX XX XX XX : call <func>
case 0xC3: // C3 : ret
case 0xEB: // EB XX : jmp XX (short jump)
case 0x70: // 7Y YY : jy XX (short conditional jump)
case 0x71:
case 0x72:
case 0x73:
case 0x74:
case 0x75:
case 0x76:
case 0x77:
case 0x78:
case 0x79:
case 0x7A:
case 0x7B:
case 0x7C:
case 0x7D:
case 0x7E:
case 0x7F:
return 0;
}
switch (*(u16*)(address)) {
case 0xFF8B: // 8B FF : mov edi, edi
case 0xEC8B: // 8B EC : mov ebp, esp
case 0xc889: // 89 C8 : mov eax, ecx
case 0xC18B: // 8B C1 : mov eax, ecx
case 0xC033: // 33 C0 : xor eax, eax
case 0xC933: // 33 C9 : xor ecx, ecx
case 0xD233: // 33 D2 : xor edx, edx
return 2;
// Cannot overwrite control-instruction. Return 0 to indicate failure.
case 0x25FF: // FF 25 XX XX XX XX : jmp [XXXXXXXX]
return 0;
}
#if SANITIZER_WINDOWS64
switch (*(u16*)address) {
case 0x5040: // push rax
case 0x5140: // push rcx
case 0x5240: // push rdx
case 0x5340: // push rbx
case 0x5440: // push rsp
case 0x5540: // push rbp
case 0x5640: // push rsi
case 0x5740: // push rdi
case 0x5441: // push r12
case 0x5541: // push r13
case 0x5641: // push r14
case 0x5741: // push r15
case 0x9066: // Two-byte NOP
return 2;
}
switch (0x00FFFFFF & *(u32*)address) {
case 0xe58948: // 48 8b c4 : mov rbp, rsp
case 0xc18b48: // 48 8b c1 : mov rax, rcx
case 0xc48b48: // 48 8b c4 : mov rax, rsp
case 0xd9f748: // 48 f7 d9 : neg rcx
case 0xd12b48: // 48 2b d1 : sub rdx, rcx
case 0x07c1f6: // f6 c1 07 : test cl, 0x7
case 0xc0854d: // 4d 85 c0 : test r8, r8
case 0xc2b60f: // 0f b6 c2 : movzx eax, dl
case 0xc03345: // 45 33 c0 : xor r8d, r8d
case 0xd98b4c: // 4c 8b d9 : mov r11, rcx
case 0xd28b4c: // 4c 8b d2 : mov r10, rdx
case 0xd2b60f: // 0f b6 d2 : movzx edx, dl
case 0xca2b48: // 48 2b ca : sub rcx, rdx
case 0x10b70f: // 0f b7 10 : movzx edx, WORD PTR [rax]
case 0xc00b4d: // 3d 0b c0 : or r8, r8
case 0xd18b48: // 48 8b d1 : mov rdx, rcx
case 0xdc8b4c: // 4c 8b dc : mov r11,rsp
case 0xd18b4c: // 4c 8b d1 : mov r10, rcx
return 3;
case 0xec8348: // 48 83 ec XX : sub rsp, XX
case 0xf88349: // 49 83 f8 XX : cmp r8, XX
case 0x588948: // 48 89 58 XX : mov QWORD PTR[rax + XX], rbx
return 4;
case 0x058b48: // 48 8b 05 XX XX XX XX :
// mov rax, QWORD PTR [rip + XXXXXXXX]
case 0x25ff48: // 48 ff 25 XX XX XX XX :
// rex.W jmp QWORD PTR [rip + XXXXXXXX]
return 7;
}
switch (*(u32*)(address)) {
case 0x24448b48: // 48 8b 44 24 XX : mov rax, qword ptr [rsp + XX]
case 0x245c8948: // 48 89 5c 24 XX : mov QWORD PTR [rsp + XX], rbx
case 0x24748948: // 48 89 74 24 XX : mov QWORD PTR [rsp + XX], rsi
return 5;
}
#else
switch (*(u16*)address) {
case 0x458B: // 8B 45 XX : mov eax, dword ptr [ebp + XX]
case 0x5D8B: // 8B 5D XX : mov ebx, dword ptr [ebp + XX]
case 0x7D8B: // 8B 7D XX : mov edi, dword ptr [ebp + XX]
case 0xEC83: // 83 EC XX : sub esp, XX
case 0x75FF: // FF 75 XX : push dword ptr [ebp + XX]
return 3;
case 0xC1F7: // F7 C1 XX YY ZZ WW : test ecx, WWZZYYXX
case 0x25FF: // FF 25 XX YY ZZ WW : jmp dword ptr ds:[WWZZYYXX]
return 6;
case 0x3D83: // 83 3D XX YY ZZ WW TT : cmp TT, WWZZYYXX
return 7;
case 0x7D83: // 83 7D XX YY : cmp dword ptr [ebp + XX], YY
return 4;
}
switch (0x00FFFFFF & *(u32*)address) {
case 0x24448A: // 8A 44 24 XX : mov eal, dword ptr [esp + XX]
case 0x24448B: // 8B 44 24 XX : mov eax, dword ptr [esp + XX]
case 0x244C8B: // 8B 4C 24 XX : mov ecx, dword ptr [esp + XX]
case 0x24548B: // 8B 54 24 XX : mov edx, dword ptr [esp + XX]
case 0x24748B: // 8B 74 24 XX : mov esi, dword ptr [esp + XX]
case 0x247C8B: // 8B 7C 24 XX : mov edi, dword ptr [esp + XX]
return 4;
}
switch (*(u32*)address) {
case 0x2444B60F: // 0F B6 44 24 XX : movzx eax, byte ptr [esp + XX]
return 5;
}
#endif
// Unknown instruction!
// FIXME: Unknown instruction failures might happen when we add a new
// interceptor or a new compiler version. In either case, they should result
// in visible and readable error messages. However, merely calling abort()
// leads to an infinite recursion in CheckFailed.
InterceptionFailed();
return 0;
}
// Returns 0 on error.
static size_t RoundUpToInstrBoundary(size_t size, uptr address) {
size_t cursor = 0;
while (cursor < size) {
size_t instruction_size = GetInstructionSize(address + cursor);
if (!instruction_size)
return 0;
cursor += instruction_size;
}
return cursor;
}
#if !SANITIZER_WINDOWS64
bool OverrideFunctionWithDetour(
uptr old_func, uptr new_func, uptr *orig_old_func) {
const int kDetourHeaderLen = 5;
const u16 kDetourInstruction = 0xFF8B;
uptr header = (uptr)old_func - kDetourHeaderLen;
uptr patch_length = kDetourHeaderLen + kShortJumpInstructionLength;
// Validate that the function is hookable.
if (*(u16*)old_func != kDetourInstruction ||
!IsMemoryPadding(header, kDetourHeaderLen))
return false;
// Change memory protection to writable.
DWORD protection = 0;
if (!ChangeMemoryProtection(header, patch_length, &protection))
return false;
// Write a relative jump to the redirected function.
WriteJumpInstruction(header, new_func);
// Write the short jump to the function prefix.
WriteShortJumpInstruction(old_func, header);
// Restore previous memory protection.
if (!RestoreMemoryProtection(header, patch_length, protection))
return false;
if (orig_old_func)
*orig_old_func = old_func + kShortJumpInstructionLength;
return true;
}
#endif
bool OverrideFunctionWithRedirectJump(
uptr old_func, uptr new_func, uptr *orig_old_func) {
// Check whether the first instruction is a relative jump.
if (*(u8*)old_func != 0xE9)
return false;
if (orig_old_func) {
uptr relative_offset = *(u32*)(old_func + 1);
uptr absolute_target = old_func + relative_offset + kJumpInstructionLength;
*orig_old_func = absolute_target;
}
#if SANITIZER_WINDOWS64
// If needed, get memory space for a trampoline jump.
uptr trampoline = AllocateMemoryForTrampoline(old_func, kDirectBranchLength);
if (!trampoline)
return false;
WriteDirectBranch(trampoline, new_func);
#endif
// Change memory protection to writable.
DWORD protection = 0;
if (!ChangeMemoryProtection(old_func, kJumpInstructionLength, &protection))
return false;
// Write a relative jump to the redirected function.
WriteJumpInstruction(old_func, FIRST_32_SECOND_64(new_func, trampoline));
// Restore previous memory protection.
if (!RestoreMemoryProtection(old_func, kJumpInstructionLength, protection))
return false;
return true;
}
bool OverrideFunctionWithHotPatch(
uptr old_func, uptr new_func, uptr *orig_old_func) {
const int kHotPatchHeaderLen = kBranchLength;
uptr header = (uptr)old_func - kHotPatchHeaderLen;
uptr patch_length = kHotPatchHeaderLen + kShortJumpInstructionLength;
// Validate that the function is hot patchable.
size_t instruction_size = GetInstructionSize(old_func);
if (instruction_size < kShortJumpInstructionLength ||
!FunctionHasPadding(old_func, kHotPatchHeaderLen))
return false;
if (orig_old_func) {
// Put the needed instructions into the trampoline bytes.
uptr trampoline_length = instruction_size + kDirectBranchLength;
uptr trampoline = AllocateMemoryForTrampoline(old_func, trampoline_length);
if (!trampoline)
return false;
CopyInstructions(trampoline, old_func, instruction_size);
WriteDirectBranch(trampoline + instruction_size,
old_func + instruction_size);
*orig_old_func = trampoline;
}
// If needed, get memory space for indirect address.
uptr indirect_address = 0;
#if SANITIZER_WINDOWS64
indirect_address = AllocateMemoryForTrampoline(old_func, kAddressLength);
if (!indirect_address)
return false;
#endif
// Change memory protection to writable.
DWORD protection = 0;
if (!ChangeMemoryProtection(header, patch_length, &protection))
return false;
// Write jumps to the redirected function.
WriteBranch(header, indirect_address, new_func);
WriteShortJumpInstruction(old_func, header);
// Restore previous memory protection.
if (!RestoreMemoryProtection(header, patch_length, protection))
return false;
return true;
}
bool OverrideFunctionWithTrampoline(
uptr old_func, uptr new_func, uptr *orig_old_func) {
size_t instructions_length = kBranchLength;
size_t padding_length = 0;
uptr indirect_address = 0;
if (orig_old_func) {
// Find out the number of bytes of the instructions we need to copy
// to the trampoline.
instructions_length = RoundUpToInstrBoundary(kBranchLength, old_func);
if (!instructions_length)
return false;
// Put the needed instructions into the trampoline bytes.
uptr trampoline_length = instructions_length + kDirectBranchLength;
uptr trampoline = AllocateMemoryForTrampoline(old_func, trampoline_length);
if (!trampoline)
return false;
CopyInstructions(trampoline, old_func, instructions_length);
WriteDirectBranch(trampoline + instructions_length,
old_func + instructions_length);
*orig_old_func = trampoline;
}
#if SANITIZER_WINDOWS64
// Check if the targeted address can be encoded in the function padding.
// Otherwise, allocate it in the trampoline region.
if (IsMemoryPadding(old_func - kAddressLength, kAddressLength)) {
indirect_address = old_func - kAddressLength;
padding_length = kAddressLength;
} else {
indirect_address = AllocateMemoryForTrampoline(old_func, kAddressLength);
if (!indirect_address)
return false;
}
#endif
// Change memory protection to writable.
uptr patch_address = old_func - padding_length;
uptr patch_length = instructions_length + padding_length;
DWORD protection = 0;
if (!ChangeMemoryProtection(patch_address, patch_length, &protection))
return false;
// Patch the original function.
WriteBranch(old_func, indirect_address, new_func);
// Restore previous memory protection.
if (!RestoreMemoryProtection(patch_address, patch_length, protection))
return false;
return true;
}
bool OverrideFunction(
uptr old_func, uptr new_func, uptr *orig_old_func) {
#if !SANITIZER_WINDOWS64
if (OverrideFunctionWithDetour(old_func, new_func, orig_old_func))
return true;
#endif
if (OverrideFunctionWithRedirectJump(old_func, new_func, orig_old_func))
return true;
if (OverrideFunctionWithHotPatch(old_func, new_func, orig_old_func))
return true;
if (OverrideFunctionWithTrampoline(old_func, new_func, orig_old_func))
return true;
return false;
}
static void **InterestingDLLsAvailable() {
static const char *InterestingDLLs[] = {
"kernel32.dll",
"msvcr110.dll", // VS2012
"msvcr120.dll", // VS2013
"vcruntime140.dll", // VS2015
"ucrtbase.dll", // Universal CRT
// NTDLL should go last as it exports some functions that we should
// override in the CRT [presumably only used internally].
"ntdll.dll", NULL};
static void *result[ARRAY_SIZE(InterestingDLLs)] = { 0 };
if (!result[0]) {
for (size_t i = 0, j = 0; InterestingDLLs[i]; ++i) {
if (HMODULE h = GetModuleHandleA(InterestingDLLs[i]))
result[j++] = (void *)h;
}
}
return &result[0];
}
namespace {
// Utility for reading loaded PE images.
template <typename T> class RVAPtr {
public:
RVAPtr(void *module, uptr rva)
: ptr_(reinterpret_cast<T *>(reinterpret_cast<char *>(module) + rva)) {}
operator T *() { return ptr_; }
T *operator->() { return ptr_; }
T *operator++() { return ++ptr_; }
private:
T *ptr_;
};
} // namespace
// Internal implementation of GetProcAddress. At least since Windows 8,
// GetProcAddress appears to initialize DLLs before returning function pointers
// into them. This is problematic for the sanitizers, because they typically
// want to intercept malloc *before* MSVCRT initializes. Our internal
// implementation walks the export list manually without doing initialization.
uptr InternalGetProcAddress(void *module, const char *func_name) {
// Check that the module header is full and present.
RVAPtr<IMAGE_DOS_HEADER> dos_stub(module, 0);
RVAPtr<IMAGE_NT_HEADERS> headers(module, dos_stub->e_lfanew);
if (!module || dos_stub->e_magic != IMAGE_DOS_SIGNATURE || // "MZ"
headers->Signature != IMAGE_NT_SIGNATURE || // "PE\0\0"
headers->FileHeader.SizeOfOptionalHeader <
sizeof(IMAGE_OPTIONAL_HEADER)) {
return 0;
}
IMAGE_DATA_DIRECTORY *export_directory =
&headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT];
RVAPtr<IMAGE_EXPORT_DIRECTORY> exports(module,
export_directory->VirtualAddress);
RVAPtr<DWORD> functions(module, exports->AddressOfFunctions);
RVAPtr<DWORD> names(module, exports->AddressOfNames);
RVAPtr<WORD> ordinals(module, exports->AddressOfNameOrdinals);
for (DWORD i = 0; i < exports->NumberOfNames; i++) {
RVAPtr<char> name(module, names[i]);
if (!strcmp(func_name, name)) {
DWORD index = ordinals[i];
RVAPtr<char> func(module, functions[index]);
return (uptr)(char *)func;
}
}
return 0;
}
static bool GetFunctionAddressInDLLs(const char *func_name, uptr *func_addr) {
*func_addr = 0;
void **DLLs = InterestingDLLsAvailable();
for (size_t i = 0; *func_addr == 0 && DLLs[i]; ++i)
*func_addr = InternalGetProcAddress(DLLs[i], func_name);
return (*func_addr != 0);
}
bool OverrideFunction(const char *name, uptr new_func, uptr *orig_old_func) {
uptr orig_func;
if (!GetFunctionAddressInDLLs(name, &orig_func))
return false;
return OverrideFunction(orig_func, new_func, orig_old_func);
}
bool OverrideImportedFunction(const char *module_to_patch,
const char *imported_module,
const char *function_name, uptr new_function,
uptr *orig_old_func) {
HMODULE module = GetModuleHandleA(module_to_patch);
if (!module)
return false;
// Check that the module header is full and present.
RVAPtr<IMAGE_DOS_HEADER> dos_stub(module, 0);
RVAPtr<IMAGE_NT_HEADERS> headers(module, dos_stub->e_lfanew);
if (!module || dos_stub->e_magic != IMAGE_DOS_SIGNATURE || // "MZ"
headers->Signature != IMAGE_NT_SIGNATURE || // "PE\0\0"
headers->FileHeader.SizeOfOptionalHeader <
sizeof(IMAGE_OPTIONAL_HEADER)) {
return false;
}
IMAGE_DATA_DIRECTORY *import_directory =
&headers->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT];
// Iterate the list of imported DLLs. FirstThunk will be null for the last
// entry.
RVAPtr<IMAGE_IMPORT_DESCRIPTOR> imports(module,
import_directory->VirtualAddress);
for (; imports->FirstThunk != 0; ++imports) {
RVAPtr<const char> modname(module, imports->Name);
if (_stricmp(&*modname, imported_module) == 0)
break;
}
if (imports->FirstThunk == 0)
return false;
// We have two parallel arrays: the import address table (IAT) and the table
// of names. They start out containing the same data, but the loader rewrites
// the IAT to hold imported addresses and leaves the name table in
// OriginalFirstThunk alone.
RVAPtr<IMAGE_THUNK_DATA> name_table(module, imports->OriginalFirstThunk);
RVAPtr<IMAGE_THUNK_DATA> iat(module, imports->FirstThunk);
for (; name_table->u1.Ordinal != 0; ++name_table, ++iat) {
if (!IMAGE_SNAP_BY_ORDINAL(name_table->u1.Ordinal)) {
RVAPtr<IMAGE_IMPORT_BY_NAME> import_by_name(
module, name_table->u1.ForwarderString);
const char *funcname = &import_by_name->Name[0];
if (strcmp(funcname, function_name) == 0)
break;
}
}
if (name_table->u1.Ordinal == 0)
return false;
// Now we have the correct IAT entry. Do the swap. We have to make the page
// read/write first.
if (orig_old_func)
*orig_old_func = iat->u1.AddressOfData;
DWORD old_prot, unused_prot;
if (!VirtualProtect(&iat->u1.AddressOfData, 4, PAGE_EXECUTE_READWRITE,
&old_prot))
return false;
iat->u1.AddressOfData = new_function;
if (!VirtualProtect(&iat->u1.AddressOfData, 4, old_prot, &unused_prot))
return false; // Not clear if this failure bothers us.
return true;
}
} // namespace __interception
#endif // _WIN32