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Diffstat (limited to 'mozglue/misc/interceptor/TargetFunction.h')
| -rw-r--r-- | mozglue/misc/interceptor/TargetFunction.h | 1000 |
1 files changed, 1000 insertions, 0 deletions
diff --git a/mozglue/misc/interceptor/TargetFunction.h b/mozglue/misc/interceptor/TargetFunction.h new file mode 100644 index 0000000000..40be1ad08b --- /dev/null +++ b/mozglue/misc/interceptor/TargetFunction.h @@ -0,0 +1,1000 @@ +/* -*- 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_TargetFunction_h +#define mozilla_interceptor_TargetFunction_h + +#include "mozilla/Assertions.h" +#include "mozilla/Attributes.h" +#include "mozilla/BinarySearch.h" +#include "mozilla/CheckedInt.h" +#include "mozilla/Maybe.h" +#include "mozilla/Tuple.h" +#include "mozilla/Types.h" +#include "mozilla/Unused.h" +#include "mozilla/Vector.h" + +#include <memory> +#include <type_traits> + +namespace mozilla { +namespace interceptor { + +#if defined(_M_IX86) + +template <typename T> +bool CommitAndWriteShortInternal(const T& aMMPolicy, void* aDest, + uint16_t aValue); + +template <> +inline bool CommitAndWriteShortInternal<MMPolicyInProcess>( + const MMPolicyInProcess& aMMPolicy, void* aDest, uint16_t aValue) { + return aMMPolicy.WriteAtomic(aDest, aValue); +} + +template <> +inline bool CommitAndWriteShortInternal<MMPolicyOutOfProcess>( + const MMPolicyOutOfProcess& aMMPolicy, void* aDest, uint16_t aValue) { + return aMMPolicy.Write(aDest, &aValue, sizeof(uint16_t)); +} + +#endif // defined(_M_IX86) + +// Forward declaration +template <typename MMPolicy> +class ReadOnlyTargetFunction; + +template <typename MMPolicy> +class MOZ_STACK_CLASS WritableTargetFunction final { + class AutoProtect final { + using ProtectParams = Tuple<uintptr_t, uint32_t>; + + public: + explicit AutoProtect(const MMPolicy& aMMPolicy) : mMMPolicy(aMMPolicy) {} + + AutoProtect(const MMPolicy& aMMPolicy, uintptr_t aAddr, size_t aNumBytes, + uint32_t aNewProt) + : mMMPolicy(aMMPolicy) { + const uint32_t pageSize = mMMPolicy.GetPageSize(); + const uintptr_t limit = aAddr + aNumBytes - 1; + const uintptr_t limitPageNum = limit / pageSize; + const uintptr_t basePageNum = aAddr / pageSize; + const uintptr_t numPagesToChange = limitPageNum - basePageNum + 1; + + // We'll use the base address of the page instead of aAddr + uintptr_t curAddr = basePageNum * pageSize; + + // Now change the protection on each page + for (uintptr_t curPage = 0; curPage < numPagesToChange; + ++curPage, curAddr += pageSize) { + uint32_t prevProt; + if (!aMMPolicy.Protect(reinterpret_cast<void*>(curAddr), pageSize, + aNewProt, &prevProt)) { + Clear(); + return; + } + + // Save the previous protection for curAddr so that we can revert this + // in the destructor. + if (!mProtects.append(MakeTuple(curAddr, prevProt))) { + Clear(); + return; + } + } + } + + AutoProtect(AutoProtect&& aOther) + : mMMPolicy(aOther.mMMPolicy), mProtects(std::move(aOther.mProtects)) { + aOther.mProtects.clear(); + } + + ~AutoProtect() { Clear(); } + + explicit operator bool() const { return !mProtects.empty(); } + + AutoProtect(const AutoProtect&) = delete; + AutoProtect& operator=(const AutoProtect&) = delete; + AutoProtect& operator=(AutoProtect&&) = delete; + + private: + void Clear() { + const uint32_t pageSize = mMMPolicy.GetPageSize(); + for (auto&& entry : mProtects) { + uint32_t prevProt; + DebugOnly<bool> ok = + mMMPolicy.Protect(reinterpret_cast<void*>(Get<0>(entry)), pageSize, + Get<1>(entry), &prevProt); + MOZ_ASSERT(ok); + } + + mProtects.clear(); + } + + private: + const MMPolicy& mMMPolicy; + // We include two entries of inline storage as that is most common in the + // worst case. + Vector<ProtectParams, 2> mProtects; + }; + + public: + /** + * Used to initialize an invalid WritableTargetFunction, thus signalling an + * error. + */ + explicit WritableTargetFunction(const MMPolicy& aMMPolicy) + : mMMPolicy(aMMPolicy), + mFunc(0), + mNumBytes(0), + mOffset(0), + mStartWriteOffset(0), + mAccumulatedStatus(false), + mProtect(aMMPolicy) {} + + WritableTargetFunction(const MMPolicy& aMMPolicy, uintptr_t aFunc, + size_t aNumBytes) + : mMMPolicy(aMMPolicy), + mFunc(aFunc), + mNumBytes(aNumBytes), + mOffset(0), + mStartWriteOffset(0), + mAccumulatedStatus(true), + mProtect(aMMPolicy, aFunc, aNumBytes, PAGE_EXECUTE_READWRITE) {} + + WritableTargetFunction(WritableTargetFunction&& aOther) + : mMMPolicy(aOther.mMMPolicy), + mFunc(aOther.mFunc), + mNumBytes(aOther.mNumBytes), + mOffset(aOther.mOffset), + mStartWriteOffset(aOther.mStartWriteOffset), + mLocalBytes(std::move(aOther.mLocalBytes)), + mAccumulatedStatus(aOther.mAccumulatedStatus), + mProtect(std::move(aOther.mProtect)) { + aOther.mAccumulatedStatus = false; + } + + ~WritableTargetFunction() { + MOZ_ASSERT(mLocalBytes.empty(), "Did you forget to call Commit?"); + } + + WritableTargetFunction(const WritableTargetFunction&) = delete; + WritableTargetFunction& operator=(const WritableTargetFunction&) = delete; + WritableTargetFunction& operator=(WritableTargetFunction&&) = delete; + + /** + * @return true if data was successfully committed. + */ + bool Commit() { + if (!(*this)) { + return false; + } + + if (mLocalBytes.empty()) { + // Nothing to commit, treat like success + return true; + } + + bool ok = + mMMPolicy.Write(reinterpret_cast<void*>(mFunc + mStartWriteOffset), + mLocalBytes.begin(), mLocalBytes.length()); + if (!ok) { + return false; + } + + mMMPolicy.FlushInstructionCache(); + + mStartWriteOffset += mLocalBytes.length(); + + mLocalBytes.clear(); + return true; + } + + explicit operator bool() const { return mProtect && mAccumulatedStatus; } + + void WriteByte(const uint8_t& aValue) { + if (!mLocalBytes.append(aValue)) { + mAccumulatedStatus = false; + return; + } + + mOffset += sizeof(uint8_t); + } + + Maybe<uint8_t> ReadByte() { + // Reading is only permitted prior to any writing + MOZ_ASSERT(mOffset == mStartWriteOffset); + if (mOffset > mStartWriteOffset) { + mAccumulatedStatus = false; + return Nothing(); + } + + uint8_t value; + if (!mMMPolicy.Read(&value, reinterpret_cast<const void*>(mFunc + mOffset), + sizeof(uint8_t))) { + mAccumulatedStatus = false; + return Nothing(); + } + + mOffset += sizeof(uint8_t); + mStartWriteOffset += sizeof(uint8_t); + return Some(value); + } + + Maybe<uintptr_t> ReadEncodedPtr() { + // Reading is only permitted prior to any writing + MOZ_ASSERT(mOffset == mStartWriteOffset); + if (mOffset > mStartWriteOffset) { + mAccumulatedStatus = false; + return Nothing(); + } + + uintptr_t value; + if (!mMMPolicy.Read(&value, reinterpret_cast<const void*>(mFunc + mOffset), + sizeof(uintptr_t))) { + mAccumulatedStatus = false; + return Nothing(); + } + + mOffset += sizeof(uintptr_t); + mStartWriteOffset += sizeof(uintptr_t); + return Some(ReadOnlyTargetFunction<MMPolicy>::DecodePtr(value)); + } + + Maybe<uint32_t> ReadLong() { + // Reading is only permitted prior to any writing + MOZ_ASSERT(mOffset == mStartWriteOffset); + if (mOffset > mStartWriteOffset) { + mAccumulatedStatus = false; + return Nothing(); + } + + uint32_t value; + if (!mMMPolicy.Read(&value, reinterpret_cast<const void*>(mFunc + mOffset), + sizeof(uint32_t))) { + mAccumulatedStatus = false; + return Nothing(); + } + + mOffset += sizeof(uint32_t); + mStartWriteOffset += sizeof(uint32_t); + return Some(value); + } + + void WriteShort(const uint16_t& aValue) { + if (!mLocalBytes.append(reinterpret_cast<const uint8_t*>(&aValue), + sizeof(uint16_t))) { + mAccumulatedStatus = false; + return; + } + + mOffset += sizeof(uint16_t); + } + +#if defined(_M_IX86) + public: + /** + * Commits any dirty writes, and then writes a short, atomically if possible. + * This call may succeed in both inproc and outproc cases, but atomicity + * is only guaranteed in the inproc case. + */ + bool CommitAndWriteShort(const uint16_t aValue) { + // First, commit everything that has been written until now + if (!Commit()) { + return false; + } + + // Now immediately write the short, atomically if inproc + bool ok = CommitAndWriteShortInternal( + mMMPolicy, reinterpret_cast<void*>(mFunc + mStartWriteOffset), aValue); + if (!ok) { + return false; + } + + mMMPolicy.FlushInstructionCache(); + mStartWriteOffset += sizeof(uint16_t); + return true; + } +#endif // defined(_M_IX86) + + void WriteDisp32(const uintptr_t aAbsTarget) { + intptr_t diff = static_cast<intptr_t>(aAbsTarget) - + static_cast<intptr_t>(mFunc + mOffset + sizeof(int32_t)); + + CheckedInt<int32_t> checkedDisp(diff); + MOZ_ASSERT(checkedDisp.isValid()); + if (!checkedDisp.isValid()) { + mAccumulatedStatus = false; + return; + } + + int32_t disp = checkedDisp.value(); + if (!mLocalBytes.append(reinterpret_cast<uint8_t*>(&disp), + sizeof(int32_t))) { + mAccumulatedStatus = false; + return; + } + + mOffset += sizeof(int32_t); + } + +#if defined(_M_X64) || defined(_M_ARM64) + void WriteLong(const uint32_t aValue) { + if (!mLocalBytes.append(reinterpret_cast<const uint8_t*>(&aValue), + sizeof(uint32_t))) { + mAccumulatedStatus = false; + return; + } + + mOffset += sizeof(uint32_t); + } +#endif // defined(_M_X64) + + void WritePointer(const uintptr_t aAbsTarget) { + if (!mLocalBytes.append(reinterpret_cast<const uint8_t*>(&aAbsTarget), + sizeof(uintptr_t))) { + mAccumulatedStatus = false; + return; + } + + mOffset += sizeof(uintptr_t); + } + + /** + * @param aValues N-sized array of type T that specifies the set of values + * that are permissible in the first M bytes of the target + * function at aOffset. + * @return true if M values of type T in the function are members of the + * set specified by aValues. + */ + template <typename T, size_t M, size_t N> + bool VerifyValuesAreOneOf(const T (&aValues)[N], const uint8_t aOffset = 0) { + T buf[M]; + if (!mMMPolicy.Read( + buf, reinterpret_cast<const void*>(mFunc + mOffset + aOffset), + M * sizeof(T))) { + return false; + } + + for (auto&& fnValue : buf) { + bool match = false; + for (auto&& testValue : aValues) { + match |= (fnValue == testValue); + } + + if (!match) { + return false; + } + } + + return true; + } + + uintptr_t GetCurrentAddress() const { return mFunc + mOffset; } + + private: + const MMPolicy& mMMPolicy; + const uintptr_t mFunc; + const size_t mNumBytes; + uint32_t mOffset; + uint32_t mStartWriteOffset; + + // In an ideal world, we'd only read 5 bytes on 32-bit and 13 bytes on 64-bit, + // to match the minimum bytes that we need to write in in order to patch the + // target function. Since the actual opcodes will often require us to pull in + // extra bytes above that minimum, we set the inline storage to be larger than + // those minima in an effort to give the Vector extra wiggle room before it + // needs to touch the heap. +#if defined(_M_IX86) + static const size_t kInlineStorage = 16; +#elif defined(_M_X64) || defined(_M_ARM64) + static const size_t kInlineStorage = 32; +#endif + Vector<uint8_t, kInlineStorage> mLocalBytes; + bool mAccumulatedStatus; + AutoProtect mProtect; +}; + +template <typename MMPolicy> +class ReadOnlyTargetBytes { + public: + ReadOnlyTargetBytes(const MMPolicy& aMMPolicy, const void* aBase) + : mMMPolicy(aMMPolicy), mBase(reinterpret_cast<const uint8_t*>(aBase)) {} + + ReadOnlyTargetBytes(ReadOnlyTargetBytes&& aOther) + : mMMPolicy(aOther.mMMPolicy), mBase(aOther.mBase) {} + + ReadOnlyTargetBytes(const ReadOnlyTargetBytes& aOther, + const uint32_t aOffsetFromOther = 0) + : mMMPolicy(aOther.mMMPolicy), mBase(aOther.mBase + aOffsetFromOther) {} + + void EnsureLimit(uint32_t aDesiredLimit) { + // In the out-proc case we use this function to read the target function's + // bytes in the other process into a local buffer. We don't need that for + // the in-process case because we already have direct access to our target + // function's bytes. + } + + uint32_t TryEnsureLimit(uint32_t aDesiredLimit) { + // Same as EnsureLimit above. We don't need to ensure for the in-process. + return aDesiredLimit; + } + + bool IsValidAtOffset(const int8_t aOffset) const { + if (!aOffset) { + return true; + } + + uintptr_t base = reinterpret_cast<uintptr_t>(mBase); + uintptr_t adjusted = base + aOffset; + uint32_t pageSize = mMMPolicy.GetPageSize(); + + // If |adjusted| is within the same page as |mBase|, we're still valid + if ((base / pageSize) == (adjusted / pageSize)) { + return true; + } + + // Otherwise, let's query |adjusted| + return mMMPolicy.IsPageAccessible(adjusted); + } + + /** + * This returns a pointer to a *potentially local copy* of the target + * function's bytes. The returned pointer should not be used for any + * pointer arithmetic relating to the target function. + */ + const uint8_t* GetLocalBytes() const { return mBase; } + + /** + * This returns a pointer to the target function's bytes. The returned pointer + * may possibly belong to another process, so while it should be used for + * pointer arithmetic, it *must not* be dereferenced. + */ + uintptr_t GetBase() const { return reinterpret_cast<uintptr_t>(mBase); } + + const MMPolicy& GetMMPolicy() const { return mMMPolicy; } + + ReadOnlyTargetBytes& operator=(const ReadOnlyTargetBytes&) = delete; + ReadOnlyTargetBytes& operator=(ReadOnlyTargetBytes&&) = delete; + + private: + const MMPolicy& mMMPolicy; + uint8_t const* const mBase; +}; + +template <> +class ReadOnlyTargetBytes<MMPolicyOutOfProcess> { + public: + ReadOnlyTargetBytes(const MMPolicyOutOfProcess& aMMPolicy, const void* aBase) + : mMMPolicy(aMMPolicy), mBase(reinterpret_cast<const uint8_t*>(aBase)) {} + + ReadOnlyTargetBytes(ReadOnlyTargetBytes&& aOther) + : mMMPolicy(aOther.mMMPolicy), + mLocalBytes(std::move(aOther.mLocalBytes)), + mBase(aOther.mBase) {} + + ReadOnlyTargetBytes(const ReadOnlyTargetBytes& aOther) + : mMMPolicy(aOther.mMMPolicy), mBase(aOther.mBase) { + Unused << mLocalBytes.appendAll(aOther.mLocalBytes); + } + + ReadOnlyTargetBytes(const ReadOnlyTargetBytes& aOther, + const uint32_t aOffsetFromOther) + : mMMPolicy(aOther.mMMPolicy), mBase(aOther.mBase + aOffsetFromOther) { + if (aOffsetFromOther >= aOther.mLocalBytes.length()) { + return; + } + + Unused << mLocalBytes.append(aOther.mLocalBytes.begin() + aOffsetFromOther, + aOther.mLocalBytes.end()); + } + + void EnsureLimit(uint32_t aDesiredLimit) { + size_t prevSize = mLocalBytes.length(); + if (aDesiredLimit < prevSize) { + return; + } + + size_t newSize = aDesiredLimit + 1; + if (newSize < kInlineStorage) { + // Always try to read as much memory as we can at once + newSize = kInlineStorage; + } + + bool resizeOk = mLocalBytes.resize(newSize); + MOZ_RELEASE_ASSERT(resizeOk); + + bool ok = mMMPolicy.Read(&mLocalBytes[prevSize], mBase + prevSize, + newSize - prevSize); + if (ok) { + return; + } + + // We couldn't pull more bytes than needed (which may happen if those extra + // bytes are not accessible). In this case, we try just to get the bare + // minimum. + newSize = aDesiredLimit + 1; + resizeOk = mLocalBytes.resize(newSize); + MOZ_RELEASE_ASSERT(resizeOk); + + ok = mMMPolicy.Read(&mLocalBytes[prevSize], mBase + prevSize, + newSize - prevSize); + MOZ_RELEASE_ASSERT(ok); + } + + // This function tries to ensure as many bytes as possible up to + // |aDesiredLimit| bytes, returning how many bytes were actually ensured. + // As EnsureLimit does, we allocate an extra byte in local to make sure + // mLocalBytes always has at least one byte even though the target memory + // was inaccessible at all. + uint32_t TryEnsureLimit(uint32_t aDesiredLimit) { + size_t prevSize = mLocalBytes.length(); + if (aDesiredLimit < prevSize) { + return aDesiredLimit; + } + + size_t newSize = aDesiredLimit; + if (newSize < kInlineStorage) { + // Always try to read as much memory as we can at once + newSize = kInlineStorage; + } + + bool resizeOk = mLocalBytes.resize(newSize); + MOZ_RELEASE_ASSERT(resizeOk); + + size_t bytesRead = mMMPolicy.TryRead(&mLocalBytes[prevSize], + mBase + prevSize, newSize - prevSize); + + newSize = prevSize + bytesRead; + + resizeOk = mLocalBytes.resize(newSize + 1); + MOZ_RELEASE_ASSERT(resizeOk); + + mLocalBytes[newSize] = 0; + return newSize; + } + + bool IsValidAtOffset(const int8_t aOffset) const { + if (!aOffset) { + return true; + } + + uintptr_t base = reinterpret_cast<uintptr_t>(mBase); + uintptr_t adjusted = base + aOffset; + uint32_t pageSize = mMMPolicy.GetPageSize(); + + // If |adjusted| is within the same page as |mBase|, we're still valid + if ((base / pageSize) == (adjusted / pageSize)) { + return true; + } + + // Otherwise, let's query |adjusted| + return mMMPolicy.IsPageAccessible(adjusted); + } + + /** + * This returns a pointer to a *potentially local copy* of the target + * function's bytes. The returned pointer should not be used for any + * pointer arithmetic relating to the target function. + */ + const uint8_t* GetLocalBytes() const { + if (mLocalBytes.empty()) { + return nullptr; + } + + return mLocalBytes.begin(); + } + + /** + * This returns a pointer to the target function's bytes. The returned pointer + * may possibly belong to another process, so while it should be used for + * pointer arithmetic, it *must not* be dereferenced. + */ + uintptr_t GetBase() const { return reinterpret_cast<uintptr_t>(mBase); } + + const MMPolicyOutOfProcess& GetMMPolicy() const { return mMMPolicy; } + + ReadOnlyTargetBytes& operator=(const ReadOnlyTargetBytes&) = delete; + ReadOnlyTargetBytes& operator=(ReadOnlyTargetBytes&&) = delete; + + private: + // In an ideal world, we'd only read 5 bytes on 32-bit and 13 bytes on 64-bit, + // to match the minimum bytes that we need to write in in order to patch the + // target function. Since the actual opcodes will often require us to pull in + // extra bytes above that minimum, we set the inline storage to be larger than + // those minima in an effort to give the Vector extra wiggle room before it + // needs to touch the heap. +#if defined(_M_IX86) + static const size_t kInlineStorage = 16; +#elif defined(_M_X64) || defined(_M_ARM64) + static const size_t kInlineStorage = 32; +#endif + + const MMPolicyOutOfProcess& mMMPolicy; + Vector<uint8_t, kInlineStorage> mLocalBytes; + uint8_t const* const mBase; +}; + +template <typename MMPolicy> +class TargetBytesPtr { + public: + typedef TargetBytesPtr<MMPolicy> Type; + + static Type Make(const MMPolicy& aMMPolicy, const void* aFunc) { + return TargetBytesPtr(aMMPolicy, aFunc); + } + + static Type CopyFromOffset(const TargetBytesPtr& aOther, + const uint32_t aOffsetFromOther) { + return TargetBytesPtr(aOther, aOffsetFromOther); + } + + ReadOnlyTargetBytes<MMPolicy>* operator->() { return &mTargetBytes; } + + TargetBytesPtr(TargetBytesPtr&& aOther) + : mTargetBytes(std::move(aOther.mTargetBytes)) {} + + TargetBytesPtr(const TargetBytesPtr& aOther) + : mTargetBytes(aOther.mTargetBytes) {} + + TargetBytesPtr& operator=(const TargetBytesPtr&) = delete; + TargetBytesPtr& operator=(TargetBytesPtr&&) = delete; + + private: + TargetBytesPtr(const MMPolicy& aMMPolicy, const void* aFunc) + : mTargetBytes(aMMPolicy, aFunc) {} + + TargetBytesPtr(const TargetBytesPtr& aOther, const uint32_t aOffsetFromOther) + : mTargetBytes(aOther.mTargetBytes, aOffsetFromOther) {} + + ReadOnlyTargetBytes<MMPolicy> mTargetBytes; +}; + +template <> +class TargetBytesPtr<MMPolicyOutOfProcess> { + public: + typedef std::shared_ptr<ReadOnlyTargetBytes<MMPolicyOutOfProcess>> Type; + + static Type Make(const MMPolicyOutOfProcess& aMMPolicy, const void* aFunc) { + return std::make_shared<ReadOnlyTargetBytes<MMPolicyOutOfProcess>>( + aMMPolicy, aFunc); + } + + static Type CopyFromOffset(const Type& aOther, + const uint32_t aOffsetFromOther) { + return std::make_shared<ReadOnlyTargetBytes<MMPolicyOutOfProcess>>( + *aOther, aOffsetFromOther); + } +}; + +template <typename MMPolicy> +class MOZ_STACK_CLASS ReadOnlyTargetFunction final { + public: + ReadOnlyTargetFunction(const MMPolicy& aMMPolicy, const void* aFunc) + : mTargetBytes(TargetBytesPtr<MMPolicy>::Make(aMMPolicy, aFunc)), + mOffset(0) {} + + ReadOnlyTargetFunction(const MMPolicy& aMMPolicy, FARPROC aFunc) + : mTargetBytes(TargetBytesPtr<MMPolicy>::Make( + aMMPolicy, reinterpret_cast<const void*>(aFunc))), + mOffset(0) {} + + ReadOnlyTargetFunction(const MMPolicy& aMMPolicy, uintptr_t aFunc) + : mTargetBytes(TargetBytesPtr<MMPolicy>::Make( + aMMPolicy, reinterpret_cast<const void*>(aFunc))), + mOffset(0) {} + + ReadOnlyTargetFunction(ReadOnlyTargetFunction&& aOther) + : mTargetBytes(std::move(aOther.mTargetBytes)), mOffset(aOther.mOffset) {} + + ReadOnlyTargetFunction& operator=(const ReadOnlyTargetFunction&) = delete; + ReadOnlyTargetFunction& operator=(ReadOnlyTargetFunction&&) = delete; + + ~ReadOnlyTargetFunction() = default; + + ReadOnlyTargetFunction operator+(const uint32_t aOffset) const { + return ReadOnlyTargetFunction(*this, mOffset + aOffset); + } + + uintptr_t GetBaseAddress() const { return mTargetBytes->GetBase(); } + + uintptr_t GetAddress() const { return mTargetBytes->GetBase() + mOffset; } + + uintptr_t AsEncodedPtr() const { + return EncodePtr( + reinterpret_cast<void*>(mTargetBytes->GetBase() + mOffset)); + } + + static uintptr_t EncodePtr(void* aPtr) { + return reinterpret_cast<uintptr_t>(::EncodePointer(aPtr)); + } + + static uintptr_t DecodePtr(uintptr_t aEncodedPtr) { + return reinterpret_cast<uintptr_t>( + ::DecodePointer(reinterpret_cast<PVOID>(aEncodedPtr))); + } + + bool IsValidAtOffset(const int8_t aOffset) const { + return mTargetBytes->IsValidAtOffset(aOffset); + } + +#if defined(_M_ARM64) + + uint32_t ReadNextInstruction() { + mTargetBytes->EnsureLimit(mOffset + sizeof(uint32_t)); + uint32_t instruction = *reinterpret_cast<const uint32_t*>( + mTargetBytes->GetLocalBytes() + mOffset); + mOffset += sizeof(uint32_t); + return instruction; + } + + bool BackUpOneInstruction() { + if (mOffset < sizeof(uint32_t)) { + return false; + } + + mOffset -= sizeof(uint32_t); + return true; + } + +#else + + uint8_t const& operator*() const { + mTargetBytes->EnsureLimit(mOffset); + return *(mTargetBytes->GetLocalBytes() + mOffset); + } + + uint8_t const& operator[](uint32_t aIndex) const { + mTargetBytes->EnsureLimit(mOffset + aIndex); + return *(mTargetBytes->GetLocalBytes() + mOffset + aIndex); + } + + ReadOnlyTargetFunction& operator++() { + ++mOffset; + return *this; + } + + ReadOnlyTargetFunction& operator+=(uint32_t aDelta) { + mOffset += aDelta; + return *this; + } + + uintptr_t ReadDisp32AsAbsolute() { + mTargetBytes->EnsureLimit(mOffset + sizeof(int32_t)); + int32_t disp = *reinterpret_cast<const int32_t*>( + mTargetBytes->GetLocalBytes() + mOffset); + uintptr_t result = + mTargetBytes->GetBase() + mOffset + sizeof(int32_t) + disp; + mOffset += sizeof(int32_t); + return result; + } + + bool IsRelativeShortJump(uintptr_t* aOutTarget) { + if ((*this)[0] == 0xeb) { + int8_t offset = static_cast<int8_t>((*this)[1]); + *aOutTarget = GetAddress() + 2 + offset; + return true; + } + return false; + } + +# if defined(_M_X64) + // Currently this function is used only in x64. + bool IsRelativeNearJump(uintptr_t* aOutTarget) { + if ((*this)[0] == 0xe9) { + *aOutTarget = (*this + 1).ReadDisp32AsAbsolute(); + return true; + } + return false; + } +# endif // defined(_M_X64) + + bool IsIndirectNearJump(uintptr_t* aOutTarget) { + if ((*this)[0] == 0xff && (*this)[1] == 0x25) { +# if defined(_M_X64) + *aOutTarget = (*this + 2).ChasePointerFromDisp(); +# else + *aOutTarget = (*this + 2).template ChasePointer<uintptr_t*>(); +# endif // defined(_M_X64) + return true; + } +# if defined(_M_X64) + else if ((*this)[0] == 0x48 && (*this)[1] == 0xff && (*this)[2] == 0x25) { + // According to Intel SDM, JMP does not have REX.W except JMP m16:64, + // but CPU can execute JMP r/m32 with REX.W. We handle it just in case. + *aOutTarget = (*this + 3).ChasePointerFromDisp(); + return true; + } +# endif // defined(_M_X64) + return false; + } + +#endif // defined(_M_ARM64) + + void Rewind() { mOffset = 0; } + + uint32_t GetOffset() const { return mOffset; } + + uintptr_t OffsetToAbsolute(const uint8_t aOffset) const { + return mTargetBytes->GetBase() + mOffset + aOffset; + } + + uintptr_t GetCurrentAbsolute() const { return OffsetToAbsolute(0); } + + /** + * This method promotes the code referenced by this object to be writable. + * + * @param aLen The length of the function's code to make writable. If set + * to zero, this object's current offset is used as the length. + * @param aOffset The result's base address will be offset from this + * object's base address by |aOffset| bytes. This value may be + * negative. + */ + WritableTargetFunction<MMPolicy> Promote(const uint32_t aLen = 0, + const int8_t aOffset = 0) const { + const uint32_t effectiveLength = aLen ? aLen : mOffset; + MOZ_RELEASE_ASSERT(effectiveLength, + "Cannot Promote a zero-length function"); + + if (!mTargetBytes->IsValidAtOffset(aOffset)) { + return WritableTargetFunction<MMPolicy>(mTargetBytes->GetMMPolicy()); + } + + WritableTargetFunction<MMPolicy> result(mTargetBytes->GetMMPolicy(), + mTargetBytes->GetBase() + aOffset, + effectiveLength); + + return result; + } + + private: + template <typename T> + struct ChasePointerHelper { + template <typename MMPolicy_> + static T Result(const MMPolicy_&, T aValue) { + return aValue; + } + }; + + template <typename T> + struct ChasePointerHelper<T*> { + template <typename MMPolicy_> + static auto Result(const MMPolicy_& aPolicy, T* aValue) { + ReadOnlyTargetFunction<MMPolicy_> ptr(aPolicy, aValue); + return ptr.template ChasePointer<T>(); + } + }; + + public: + // Keep chasing pointers until T is not a pointer type anymore + template <typename T> + auto ChasePointer() { + mTargetBytes->EnsureLimit(mOffset + sizeof(T)); + const std::remove_cv_t<T> result = + *reinterpret_cast<const std::remove_cv_t<T>*>( + mTargetBytes->GetLocalBytes() + mOffset); + return ChasePointerHelper<std::remove_cv_t<T>>::Result( + mTargetBytes->GetMMPolicy(), result); + } + + uintptr_t ChasePointerFromDisp() { + uintptr_t ptrFromDisp = ReadDisp32AsAbsolute(); + ReadOnlyTargetFunction<MMPolicy> ptr( + mTargetBytes->GetMMPolicy(), + reinterpret_cast<const void*>(ptrFromDisp)); + return ptr.template ChasePointer<uintptr_t>(); + } + + private: + ReadOnlyTargetFunction(const ReadOnlyTargetFunction& aOther) + : mTargetBytes(aOther.mTargetBytes), mOffset(aOther.mOffset) {} + + ReadOnlyTargetFunction(const ReadOnlyTargetFunction& aOther, + const uint32_t aOffsetFromOther) + : mTargetBytes(TargetBytesPtr<MMPolicy>::CopyFromOffset( + aOther.mTargetBytes, aOffsetFromOther)), + mOffset(0) {} + + private: + mutable typename TargetBytesPtr<MMPolicy>::Type mTargetBytes; + uint32_t mOffset; +}; + +template <typename MMPolicy, typename T> +class MOZ_STACK_CLASS TargetObject { + mutable typename TargetBytesPtr<MMPolicy>::Type mTargetBytes; + + TargetObject(const MMPolicy& aMMPolicy, const void* aBaseAddress) + : mTargetBytes(TargetBytesPtr<MMPolicy>::Make(aMMPolicy, aBaseAddress)) { + mTargetBytes->EnsureLimit(sizeof(T)); + } + + public: + explicit TargetObject(const MMPolicy& aMMPolicy) + : mTargetBytes(TargetBytesPtr<MMPolicy>::Make(aMMPolicy, nullptr)) {} + + TargetObject(const MMPolicy& aMMPolicy, uintptr_t aBaseAddress) + : TargetObject(aMMPolicy, reinterpret_cast<const void*>(aBaseAddress)) {} + + TargetObject(const TargetObject&) = delete; + TargetObject(TargetObject&&) = delete; + TargetObject& operator=(const TargetObject&) = delete; + TargetObject& operator=(TargetObject&&) = delete; + + explicit operator bool() const { + return mTargetBytes->GetBase() && mTargetBytes->GetLocalBytes(); + } + + const T* operator->() const { + return reinterpret_cast<const T*>(mTargetBytes->GetLocalBytes()); + } + + const T* GetLocalBase() const { + return reinterpret_cast<const T*>(mTargetBytes->GetLocalBytes()); + } +}; + +template <typename MMPolicy, typename T> +class MOZ_STACK_CLASS TargetObjectArray { + mutable typename TargetBytesPtr<MMPolicy>::Type mTargetBytes; + size_t mNumOfItems; + + TargetObjectArray(const MMPolicy& aMMPolicy, const void* aBaseAddress, + size_t aNumOfItems) + : mTargetBytes(TargetBytesPtr<MMPolicy>::Make(aMMPolicy, aBaseAddress)), + mNumOfItems(aNumOfItems) { + uint32_t itemsRead = + mTargetBytes->TryEnsureLimit(sizeof(T) * mNumOfItems) / sizeof(T); + // itemsRead may be bigger than the requested amount because of buffering, + // but mNumOfItems should not include extra bytes of buffering. + if (itemsRead < mNumOfItems) { + mNumOfItems = itemsRead; + } + } + + const T* GetLocalBase() const { + return reinterpret_cast<const T*>(mTargetBytes->GetLocalBytes()); + } + + public: + explicit TargetObjectArray(const MMPolicy& aMMPolicy) + : mTargetBytes(TargetBytesPtr<MMPolicy>::Make(aMMPolicy, nullptr)), + mNumOfItems(0) {} + + TargetObjectArray(const MMPolicy& aMMPolicy, uintptr_t aBaseAddress, + size_t aNumOfItems) + : TargetObjectArray(aMMPolicy, + reinterpret_cast<const void*>(aBaseAddress), + aNumOfItems) {} + + TargetObjectArray(const TargetObjectArray&) = delete; + TargetObjectArray(TargetObjectArray&&) = delete; + TargetObjectArray& operator=(const TargetObjectArray&) = delete; + TargetObjectArray& operator=(TargetObjectArray&&) = delete; + + explicit operator bool() const { + return mTargetBytes->GetBase() && mNumOfItems; + } + + const T* operator[](size_t aIndex) const { + if (aIndex >= mNumOfItems) { + return nullptr; + } + + return &GetLocalBase()[aIndex]; + } + + template <typename Comparator> + bool BinarySearchIf(const Comparator& aCompare, + size_t* aMatchOrInsertionPoint) const { + return mozilla::BinarySearchIf(GetLocalBase(), 0, mNumOfItems, aCompare, + aMatchOrInsertionPoint); + } +}; + +} // namespace interceptor +} // namespace mozilla + +#endif // mozilla_interceptor_TargetFunction_h |