gecko-dev/mozglue/misc/interceptor/Trampoline.h

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9.2 KiB
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
#ifndef mozilla_interceptor_Trampoline_h
#define mozilla_interceptor_Trampoline_h
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"
#include "mozilla/Types.h"
namespace mozilla {
namespace interceptor {
template <typename MMPolicy>
class MOZ_STACK_CLASS Trampoline final
{
public:
Trampoline(const MMPolicy* aMMPolicy, uint8_t* const aLocalBase,
const uintptr_t aRemoteBase, const uint32_t aChunkSize)
: mMMPolicy(aMMPolicy)
, mPrevLocalProt(0)
, mLocalBase(aLocalBase)
, mRemoteBase(aRemoteBase)
, mOffset(0)
, mExeOffset(0)
, mMaxOffset(aChunkSize)
, mAccumulatedStatus(true)
{
::VirtualProtect(aLocalBase, aChunkSize, PAGE_EXECUTE_READWRITE,
&mPrevLocalProt);
}
Trampoline(Trampoline&& aOther)
: mMMPolicy(aOther.mMMPolicy)
, mPrevLocalProt(aOther.mPrevLocalProt)
, mLocalBase(aOther.mLocalBase)
, mRemoteBase(aOther.mRemoteBase)
, mOffset(aOther.mOffset)
, mExeOffset(aOther.mExeOffset)
, mMaxOffset(aOther.mMaxOffset)
, mAccumulatedStatus(aOther.mAccumulatedStatus)
{
aOther.mPrevLocalProt = 0;
aOther.mAccumulatedStatus = false;
}
MOZ_IMPLICIT Trampoline(decltype(nullptr))
: mMMPolicy(nullptr)
, mPrevLocalProt(0)
, mLocalBase(nullptr)
, mRemoteBase(0)
, mOffset(0)
, mExeOffset(0)
, mMaxOffset(0)
, mAccumulatedStatus(false)
{
}
Trampoline(const Trampoline&) = delete;
Trampoline& operator=(const Trampoline&) = delete;
Trampoline&& operator=(Trampoline&&) = delete;
~Trampoline()
{
if (!mLocalBase || !mPrevLocalProt) {
return;
}
::VirtualProtect(mLocalBase, mMaxOffset, mPrevLocalProt, &mPrevLocalProt);
}
explicit operator bool() const
{
return mLocalBase && mRemoteBase && mPrevLocalProt && mAccumulatedStatus;
}
void WriteByte(uint8_t aValue)
{
if (mOffset >= mMaxOffset) {
mAccumulatedStatus = false;
return;
}
*(mLocalBase + mOffset) = aValue;
++mOffset;
}
void WriteInteger(int32_t aValue)
{
if (mOffset + sizeof(int32_t) > mMaxOffset) {
mAccumulatedStatus = false;
return;
}
*reinterpret_cast<int32_t*>(mLocalBase + mOffset) = aValue;
mOffset += sizeof(int32_t);
}
void WritePointer(uintptr_t aValue)
{
if (mOffset + sizeof(uintptr_t) > mMaxOffset) {
mAccumulatedStatus = false;
return;
}
*reinterpret_cast<uintptr_t*>(mLocalBase + mOffset) = aValue;
mOffset += sizeof(uintptr_t);
}
void WriteEncodedPointer(void* aValue)
{
uintptr_t encoded = ReadOnlyTargetFunction<MMPolicy>::EncodePtr(aValue);
WritePointer(encoded);
}
Maybe<uintptr_t> ReadPointer()
{
if (mOffset + sizeof(uintptr_t) > mMaxOffset) {
mAccumulatedStatus = false;
return Nothing();
}
auto result = Some(*reinterpret_cast<uintptr_t*>(mLocalBase + mOffset));
mOffset += sizeof(uintptr_t);
return Move(result);
}
Maybe<uintptr_t> ReadEncodedPointer()
{
Maybe<uintptr_t> encoded(ReadPointer());
if (!encoded) {
return encoded;
}
return Some(ReadOnlyTargetFunction<MMPolicy>::DecodePtr(encoded.value()));
}
void WriteDisp32(uintptr_t aAbsTarget)
{
if (mOffset + sizeof(int32_t) > mMaxOffset) {
mAccumulatedStatus = false;
return;
}
// This needs to be computed from the remote location
intptr_t remoteTrampPosition = static_cast<intptr_t>(mRemoteBase + mOffset);
intptr_t diff = static_cast<intptr_t>(aAbsTarget) -
(remoteTrampPosition + sizeof(int32_t));
CheckedInt<int32_t> checkedDisp(diff);
MOZ_ASSERT(checkedDisp.isValid());
if (!checkedDisp.isValid()) {
mAccumulatedStatus = false;
return;
}
int32_t disp = checkedDisp.value();
*reinterpret_cast<int32_t*>(mLocalBase + mOffset) = disp;
mOffset += sizeof(int32_t);
}
#if defined(_M_IX86)
// 32-bit only
void AdjustDisp32AtOffset(uint32_t aOffset, uintptr_t aAbsTarget)
{
uint32_t effectiveOffset = mExeOffset + aOffset;
if (effectiveOffset + sizeof(int32_t) > mMaxOffset) {
mAccumulatedStatus = false;
return;
}
intptr_t diff = static_cast<intptr_t>(aAbsTarget) -
static_cast<intptr_t>(mRemoteBase + mExeOffset);
*reinterpret_cast<int32_t*>(mLocalBase + effectiveOffset) += diff;
}
#endif // defined(_M_IX86)
void CopyFrom(uintptr_t aOrigBytes, uint32_t aNumBytes)
{
if (!mMMPolicy || mOffset + aNumBytes > mMaxOffset) {
mAccumulatedStatus = false;
return;
}
if (!mMMPolicy->Read(mLocalBase + mOffset,
reinterpret_cast<void*>(aOrigBytes), aNumBytes)) {
mAccumulatedStatus = false;
return;
}
mOffset += aNumBytes;
}
void Rewind()
{
mOffset = 0;
}
uintptr_t GetCurrentRemoteAddress() const
{
return mRemoteBase + mOffset;
}
void StartExecutableCode()
{
MOZ_ASSERT(!mExeOffset);
mExeOffset = mOffset;
}
void* EndExecutableCode() const
{
if (!mAccumulatedStatus) {
return nullptr;
}
// This must always return the start address the executable code
// *in the target process*
return reinterpret_cast<void*>(mRemoteBase + mExeOffset);
}
Trampoline<MMPolicy>& operator--()
{
MOZ_ASSERT(mOffset);
--mOffset;
return *this;
}
private:
const MMPolicy* mMMPolicy;
DWORD mPrevLocalProt;
uint8_t* const mLocalBase;
const uintptr_t mRemoteBase;
uint32_t mOffset;
uint32_t mExeOffset;
const uint32_t mMaxOffset;
bool mAccumulatedStatus;
};
template <typename MMPolicy>
class MOZ_STACK_CLASS TrampolineCollection final
{
public:
class MOZ_STACK_CLASS TrampolineIterator final
{
public:
Trampoline<MMPolicy> operator*()
{
uint32_t offset = mCurTramp * mCollection.mTrampSize;
return Trampoline<MMPolicy>(nullptr,
mCollection.mLocalBase + offset,
mCollection.mRemoteBase + offset,
mCollection.mTrampSize);
}
TrampolineIterator& operator++()
{
++mCurTramp;
return *this;
}
bool operator!=(const TrampolineIterator& aOther) const
{
return mCurTramp != aOther.mCurTramp;
}
private:
explicit TrampolineIterator(
const TrampolineCollection<MMPolicy>& aCollection,
const uint32_t aCurTramp = 0)
: mCollection(aCollection)
, mCurTramp(aCurTramp)
{
}
const TrampolineCollection<MMPolicy>& mCollection;
uint32_t mCurTramp;
friend class TrampolineCollection<MMPolicy>;
};
explicit TrampolineCollection(const MMPolicy& aMMPolicy)
: mMMPolicy(aMMPolicy)
, mLocalBase(0)
, mRemoteBase(0)
, mTrampSize(0)
, mNumTramps(0)
, mPrevProt(0)
, mCS(nullptr)
{
}
TrampolineCollection(const MMPolicy& aMMPolicy, uint8_t* const aLocalBase,
const uintptr_t aRemoteBase, const uint32_t aTrampSize,
const uint32_t aNumTramps)
: mMMPolicy(aMMPolicy)
, mLocalBase(aLocalBase)
, mRemoteBase(aRemoteBase)
, mTrampSize(aTrampSize)
, mNumTramps(aNumTramps)
, mPrevProt(0)
, mCS(nullptr)
{
if (!aNumTramps) {
return;
}
DebugOnly<BOOL> ok = mMMPolicy.Protect(aLocalBase, aNumTramps * aTrampSize,
PAGE_EXECUTE_READWRITE, &mPrevProt);
MOZ_ASSERT(ok);
}
~TrampolineCollection()
{
if (!mPrevProt) {
return;
}
mMMPolicy.Protect(mLocalBase, mNumTramps * mTrampSize,
mPrevProt, &mPrevProt);
if (mCS) {
::LeaveCriticalSection(mCS);
}
}
void Lock(CRITICAL_SECTION& aCS)
{
if (!mPrevProt || mCS) {
return;
}
mCS = &aCS;
::EnterCriticalSection(&aCS);
}
TrampolineIterator begin() const
{
if (!mPrevProt) {
return end();
}
return TrampolineIterator(*this);
}
TrampolineIterator end() const
{
return TrampolineIterator(*this, mNumTramps);
}
TrampolineCollection(const TrampolineCollection&) = delete;
TrampolineCollection& operator=(const TrampolineCollection&) = delete;
TrampolineCollection& operator=(TrampolineCollection&&) = delete;
TrampolineCollection(TrampolineCollection&& aOther)
: mMMPolicy(aOther.mMMPolicy)
, mLocalBase(aOther.mLocalBase)
, mRemoteBase(aOther.mRemoteBase)
, mTrampSize(aOther.mTrampSize)
, mNumTramps(aOther.mNumTramps)
, mPrevProt(aOther.mPrevProt)
, mCS(aOther.mCS)
{
aOther.mPrevProt = 0;
aOther.mCS = nullptr;
}
private:
const MMPolicy& mMMPolicy;
uint8_t* const mLocalBase;
const uintptr_t mRemoteBase;
const uint32_t mTrampSize;
const uint32_t mNumTramps;
uint32_t mPrevProt;
CRITICAL_SECTION* mCS;
friend class TrampolineIterator;
};
} // namespace interceptor
} // namespace mozilla
#endif // mozilla_interceptor_Trampoline_h