| //===-- IRDynamicChecks.cpp -----------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/IR/Constants.h" |
| #include "llvm/IR/DataLayout.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/Module.h" |
| #include "llvm/IR/Value.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| #include "IRDynamicChecks.h" |
| |
| #include "lldb/Expression/UtilityFunction.h" |
| #include "lldb/Target/ExecutionContext.h" |
| #include "lldb/Target/Process.h" |
| #include "lldb/Target/StackFrame.h" |
| #include "lldb/Target/Target.h" |
| #include "lldb/Utility/ConstString.h" |
| #include "lldb/Utility/LLDBLog.h" |
| #include "lldb/Utility/Log.h" |
| |
| #include "Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h" |
| |
| using namespace llvm; |
| using namespace lldb_private; |
| |
| static char ID; |
| |
| #define VALID_POINTER_CHECK_NAME "_$__lldb_valid_pointer_check" |
| #define VALID_OBJC_OBJECT_CHECK_NAME "$__lldb_objc_object_check" |
| |
| static const char g_valid_pointer_check_text[] = |
| "extern \"C\" void\n" |
| "_$__lldb_valid_pointer_check (unsigned char *$__lldb_arg_ptr)\n" |
| "{\n" |
| " unsigned char $__lldb_local_val = *$__lldb_arg_ptr;\n" |
| "}"; |
| |
| ClangDynamicCheckerFunctions::ClangDynamicCheckerFunctions() |
| : DynamicCheckerFunctions(DCF_Clang) {} |
| |
| ClangDynamicCheckerFunctions::~ClangDynamicCheckerFunctions() = default; |
| |
| llvm::Error ClangDynamicCheckerFunctions::Install( |
| DiagnosticManager &diagnostic_manager, ExecutionContext &exe_ctx) { |
| Expected<std::unique_ptr<UtilityFunction>> utility_fn = |
| exe_ctx.GetTargetRef().CreateUtilityFunction( |
| g_valid_pointer_check_text, VALID_POINTER_CHECK_NAME, |
| lldb::eLanguageTypeC, exe_ctx); |
| if (!utility_fn) |
| return utility_fn.takeError(); |
| m_valid_pointer_check = std::move(*utility_fn); |
| |
| if (Process *process = exe_ctx.GetProcessPtr()) { |
| ObjCLanguageRuntime *objc_language_runtime = |
| ObjCLanguageRuntime::Get(*process); |
| |
| if (objc_language_runtime) { |
| Expected<std::unique_ptr<UtilityFunction>> checker_fn = |
| objc_language_runtime->CreateObjectChecker(VALID_OBJC_OBJECT_CHECK_NAME, exe_ctx); |
| if (!checker_fn) |
| return checker_fn.takeError(); |
| m_objc_object_check = std::move(*checker_fn); |
| } |
| } |
| |
| return Error::success(); |
| } |
| |
| bool ClangDynamicCheckerFunctions::DoCheckersExplainStop(lldb::addr_t addr, |
| Stream &message) { |
| // FIXME: We have to get the checkers to know why they scotched the call in |
| // more detail, |
| // so we can print a better message here. |
| if (m_valid_pointer_check && m_valid_pointer_check->ContainsAddress(addr)) { |
| message.Printf("Attempted to dereference an invalid pointer."); |
| return true; |
| } else if (m_objc_object_check && |
| m_objc_object_check->ContainsAddress(addr)) { |
| message.Printf("Attempted to dereference an invalid ObjC Object or send it " |
| "an unrecognized selector"); |
| return true; |
| } |
| return false; |
| } |
| |
| static std::string PrintValue(llvm::Value *V, bool truncate = false) { |
| std::string s; |
| raw_string_ostream rso(s); |
| V->print(rso); |
| rso.flush(); |
| if (truncate) |
| s.resize(s.length() - 1); |
| return s; |
| } |
| |
| /// \class Instrumenter IRDynamicChecks.cpp |
| /// Finds and instruments individual LLVM IR instructions |
| /// |
| /// When instrumenting LLVM IR, it is frequently desirable to first search for |
| /// instructions, and then later modify them. This way iterators remain |
| /// intact, and multiple passes can look at the same code base without |
| /// treading on each other's toes. |
| /// |
| /// The Instrumenter class implements this functionality. A client first |
| /// calls Inspect on a function, which populates a list of instructions to be |
| /// instrumented. Then, later, when all passes' Inspect functions have been |
| /// called, the client calls Instrument, which adds the desired |
| /// instrumentation. |
| /// |
| /// A subclass of Instrumenter must override InstrumentInstruction, which |
| /// is responsible for adding whatever instrumentation is necessary. |
| /// |
| /// A subclass of Instrumenter may override: |
| /// |
| /// - InspectInstruction [default: does nothing] |
| /// |
| /// - InspectBasicBlock [default: iterates through the instructions in a |
| /// basic block calling InspectInstruction] |
| /// |
| /// - InspectFunction [default: iterates through the basic blocks in a |
| /// function calling InspectBasicBlock] |
| class Instrumenter { |
| public: |
| /// Constructor |
| /// |
| /// \param[in] module |
| /// The module being instrumented. |
| Instrumenter(llvm::Module &module, |
| std::shared_ptr<UtilityFunction> checker_function) |
| : m_module(module), m_checker_function(checker_function) {} |
| |
| virtual ~Instrumenter() = default; |
| |
| /// Inspect a function to find instructions to instrument |
| /// |
| /// \param[in] function |
| /// The function to inspect. |
| /// |
| /// \return |
| /// True on success; false on error. |
| bool Inspect(llvm::Function &function) { return InspectFunction(function); } |
| |
| /// Instrument all the instructions found by Inspect() |
| /// |
| /// \return |
| /// True on success; false on error. |
| bool Instrument() { |
| for (InstIterator ii = m_to_instrument.begin(), |
| last_ii = m_to_instrument.end(); |
| ii != last_ii; ++ii) { |
| if (!InstrumentInstruction(*ii)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| protected: |
| /// Add instrumentation to a single instruction |
| /// |
| /// \param[in] inst |
| /// The instruction to be instrumented. |
| /// |
| /// \return |
| /// True on success; false otherwise. |
| virtual bool InstrumentInstruction(llvm::Instruction *inst) = 0; |
| |
| /// Register a single instruction to be instrumented |
| /// |
| /// \param[in] inst |
| /// The instruction to be instrumented. |
| void RegisterInstruction(llvm::Instruction &inst) { |
| m_to_instrument.push_back(&inst); |
| } |
| |
| /// Determine whether a single instruction is interesting to instrument, |
| /// and, if so, call RegisterInstruction |
| /// |
| /// \param[in] i |
| /// The instruction to be inspected. |
| /// |
| /// \return |
| /// False if there was an error scanning; true otherwise. |
| virtual bool InspectInstruction(llvm::Instruction &i) { return true; } |
| |
| /// Scan a basic block to see if any instructions are interesting |
| /// |
| /// \param[in] bb |
| /// The basic block to be inspected. |
| /// |
| /// \return |
| /// False if there was an error scanning; true otherwise. |
| virtual bool InspectBasicBlock(llvm::BasicBlock &bb) { |
| for (llvm::BasicBlock::iterator ii = bb.begin(), last_ii = bb.end(); |
| ii != last_ii; ++ii) { |
| if (!InspectInstruction(*ii)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /// Scan a function to see if any instructions are interesting |
| /// |
| /// \param[in] f |
| /// The function to be inspected. |
| /// |
| /// \return |
| /// False if there was an error scanning; true otherwise. |
| virtual bool InspectFunction(llvm::Function &f) { |
| for (llvm::Function::iterator bbi = f.begin(), last_bbi = f.end(); |
| bbi != last_bbi; ++bbi) { |
| if (!InspectBasicBlock(*bbi)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /// Build a function pointer for a function with signature void |
| /// (*)(uint8_t*) with a given address |
| /// |
| /// \param[in] start_address |
| /// The address of the function. |
| /// |
| /// \return |
| /// The function pointer, for use in a CallInst. |
| llvm::FunctionCallee BuildPointerValidatorFunc(lldb::addr_t start_address) { |
| llvm::Type *param_array[1]; |
| |
| param_array[0] = const_cast<llvm::PointerType *>(GetI8PtrTy()); |
| |
| ArrayRef<llvm::Type *> params(param_array, 1); |
| |
| FunctionType *fun_ty = FunctionType::get( |
| llvm::Type::getVoidTy(m_module.getContext()), params, true); |
| PointerType *fun_ptr_ty = PointerType::getUnqual(fun_ty); |
| Constant *fun_addr_int = |
| ConstantInt::get(GetIntptrTy(), start_address, false); |
| return {fun_ty, ConstantExpr::getIntToPtr(fun_addr_int, fun_ptr_ty)}; |
| } |
| |
| /// Build a function pointer for a function with signature void |
| /// (*)(uint8_t*, uint8_t*) with a given address |
| /// |
| /// \param[in] start_address |
| /// The address of the function. |
| /// |
| /// \return |
| /// The function pointer, for use in a CallInst. |
| llvm::FunctionCallee BuildObjectCheckerFunc(lldb::addr_t start_address) { |
| llvm::Type *param_array[2]; |
| |
| param_array[0] = const_cast<llvm::PointerType *>(GetI8PtrTy()); |
| param_array[1] = const_cast<llvm::PointerType *>(GetI8PtrTy()); |
| |
| ArrayRef<llvm::Type *> params(param_array, 2); |
| |
| FunctionType *fun_ty = FunctionType::get( |
| llvm::Type::getVoidTy(m_module.getContext()), params, true); |
| PointerType *fun_ptr_ty = PointerType::getUnqual(fun_ty); |
| Constant *fun_addr_int = |
| ConstantInt::get(GetIntptrTy(), start_address, false); |
| return {fun_ty, ConstantExpr::getIntToPtr(fun_addr_int, fun_ptr_ty)}; |
| } |
| |
| PointerType *GetI8PtrTy() { |
| if (!m_i8ptr_ty) |
| m_i8ptr_ty = llvm::PointerType::getUnqual(m_module.getContext()); |
| |
| return m_i8ptr_ty; |
| } |
| |
| IntegerType *GetIntptrTy() { |
| if (!m_intptr_ty) { |
| llvm::DataLayout data_layout(&m_module); |
| |
| m_intptr_ty = llvm::Type::getIntNTy(m_module.getContext(), |
| data_layout.getPointerSizeInBits()); |
| } |
| |
| return m_intptr_ty; |
| } |
| |
| typedef std::vector<llvm::Instruction *> InstVector; |
| typedef InstVector::iterator InstIterator; |
| |
| InstVector m_to_instrument; ///< List of instructions the inspector found |
| llvm::Module &m_module; ///< The module which is being instrumented |
| std::shared_ptr<UtilityFunction> |
| m_checker_function; ///< The dynamic checker function for the process |
| |
| private: |
| PointerType *m_i8ptr_ty = nullptr; |
| IntegerType *m_intptr_ty = nullptr; |
| }; |
| |
| class ValidPointerChecker : public Instrumenter { |
| public: |
| ValidPointerChecker(llvm::Module &module, |
| std::shared_ptr<UtilityFunction> checker_function) |
| : Instrumenter(module, checker_function), |
| m_valid_pointer_check_func(nullptr) {} |
| |
| ~ValidPointerChecker() override = default; |
| |
| protected: |
| bool InstrumentInstruction(llvm::Instruction *inst) override { |
| Log *log = GetLog(LLDBLog::Expressions); |
| |
| LLDB_LOGF(log, "Instrumenting load/store instruction: %s\n", |
| PrintValue(inst).c_str()); |
| |
| if (!m_valid_pointer_check_func) |
| m_valid_pointer_check_func = |
| BuildPointerValidatorFunc(m_checker_function->StartAddress()); |
| |
| llvm::Value *dereferenced_ptr = nullptr; |
| |
| if (llvm::LoadInst *li = dyn_cast<llvm::LoadInst>(inst)) |
| dereferenced_ptr = li->getPointerOperand(); |
| else if (llvm::StoreInst *si = dyn_cast<llvm::StoreInst>(inst)) |
| dereferenced_ptr = si->getPointerOperand(); |
| else |
| return false; |
| |
| // Insert an instruction to call the helper with the result |
| CallInst::Create(m_valid_pointer_check_func, dereferenced_ptr, "", inst); |
| |
| return true; |
| } |
| |
| bool InspectInstruction(llvm::Instruction &i) override { |
| if (isa<llvm::LoadInst>(&i) || isa<llvm::StoreInst>(&i)) |
| RegisterInstruction(i); |
| |
| return true; |
| } |
| |
| private: |
| llvm::FunctionCallee m_valid_pointer_check_func; |
| }; |
| |
| class ObjcObjectChecker : public Instrumenter { |
| public: |
| ObjcObjectChecker(llvm::Module &module, |
| std::shared_ptr<UtilityFunction> checker_function) |
| : Instrumenter(module, checker_function), |
| m_objc_object_check_func(nullptr) {} |
| |
| ~ObjcObjectChecker() override = default; |
| |
| enum msgSend_type { |
| eMsgSend = 0, |
| eMsgSendSuper, |
| eMsgSendSuper_stret, |
| eMsgSend_fpret, |
| eMsgSend_stret |
| }; |
| |
| std::map<llvm::Instruction *, msgSend_type> msgSend_types; |
| |
| protected: |
| bool InstrumentInstruction(llvm::Instruction *inst) override { |
| CallInst *call_inst = dyn_cast<CallInst>(inst); |
| |
| if (!call_inst) |
| return false; // call_inst really shouldn't be nullptr, because otherwise |
| // InspectInstruction wouldn't have registered it |
| |
| if (!m_objc_object_check_func) |
| m_objc_object_check_func = |
| BuildObjectCheckerFunc(m_checker_function->StartAddress()); |
| |
| // id objc_msgSend(id theReceiver, SEL theSelector, ...) |
| |
| llvm::Value *target_object; |
| llvm::Value *selector; |
| |
| switch (msgSend_types[inst]) { |
| case eMsgSend: |
| case eMsgSend_fpret: |
| // On arm64, clang uses objc_msgSend for scalar and struct return |
| // calls. The call instruction will record which was used. |
| if (call_inst->hasStructRetAttr()) { |
| target_object = call_inst->getArgOperand(1); |
| selector = call_inst->getArgOperand(2); |
| } else { |
| target_object = call_inst->getArgOperand(0); |
| selector = call_inst->getArgOperand(1); |
| } |
| break; |
| case eMsgSend_stret: |
| target_object = call_inst->getArgOperand(1); |
| selector = call_inst->getArgOperand(2); |
| break; |
| case eMsgSendSuper: |
| case eMsgSendSuper_stret: |
| return true; |
| } |
| |
| // These objects should always be valid according to Sean Calannan |
| assert(target_object); |
| assert(selector); |
| |
| // Insert an instruction to call the helper with the result |
| |
| llvm::Value *arg_array[2]; |
| |
| arg_array[0] = target_object; |
| arg_array[1] = selector; |
| |
| ArrayRef<llvm::Value *> args(arg_array, 2); |
| |
| CallInst::Create(m_objc_object_check_func, args, "", inst); |
| |
| return true; |
| } |
| |
| static llvm::Function *GetFunction(llvm::Value *value) { |
| if (llvm::Function *function = llvm::dyn_cast<llvm::Function>(value)) { |
| return function; |
| } |
| |
| if (llvm::ConstantExpr *const_expr = |
| llvm::dyn_cast<llvm::ConstantExpr>(value)) { |
| switch (const_expr->getOpcode()) { |
| default: |
| return nullptr; |
| case llvm::Instruction::BitCast: |
| return GetFunction(const_expr->getOperand(0)); |
| } |
| } |
| |
| return nullptr; |
| } |
| |
| static llvm::Function *GetCalledFunction(llvm::CallInst *inst) { |
| return GetFunction(inst->getCalledOperand()); |
| } |
| |
| bool InspectInstruction(llvm::Instruction &i) override { |
| Log *log = GetLog(LLDBLog::Expressions); |
| |
| CallInst *call_inst = dyn_cast<CallInst>(&i); |
| |
| if (call_inst) { |
| const llvm::Function *called_function = GetCalledFunction(call_inst); |
| |
| if (!called_function) |
| return true; |
| |
| std::string name_str = called_function->getName().str(); |
| const char *name_cstr = name_str.c_str(); |
| |
| LLDB_LOGF(log, "Found call to %s: %s\n", name_cstr, |
| PrintValue(call_inst).c_str()); |
| |
| if (name_str.find("objc_msgSend") == std::string::npos) |
| return true; |
| |
| if (!strcmp(name_cstr, "objc_msgSend")) { |
| RegisterInstruction(i); |
| msgSend_types[&i] = eMsgSend; |
| return true; |
| } |
| |
| if (!strcmp(name_cstr, "objc_msgSend_stret")) { |
| RegisterInstruction(i); |
| msgSend_types[&i] = eMsgSend_stret; |
| return true; |
| } |
| |
| if (!strcmp(name_cstr, "objc_msgSend_fpret")) { |
| RegisterInstruction(i); |
| msgSend_types[&i] = eMsgSend_fpret; |
| return true; |
| } |
| |
| if (!strcmp(name_cstr, "objc_msgSendSuper")) { |
| RegisterInstruction(i); |
| msgSend_types[&i] = eMsgSendSuper; |
| return true; |
| } |
| |
| if (!strcmp(name_cstr, "objc_msgSendSuper_stret")) { |
| RegisterInstruction(i); |
| msgSend_types[&i] = eMsgSendSuper_stret; |
| return true; |
| } |
| |
| LLDB_LOGF(log, |
| "Function name '%s' contains 'objc_msgSend' but is not handled", |
| name_str.c_str()); |
| |
| return true; |
| } |
| |
| return true; |
| } |
| |
| private: |
| llvm::FunctionCallee m_objc_object_check_func; |
| }; |
| |
| IRDynamicChecks::IRDynamicChecks( |
| ClangDynamicCheckerFunctions &checker_functions, const char *func_name) |
| : ModulePass(ID), m_func_name(func_name), |
| m_checker_functions(checker_functions) {} |
| |
| IRDynamicChecks::~IRDynamicChecks() = default; |
| |
| bool IRDynamicChecks::runOnModule(llvm::Module &M) { |
| Log *log = GetLog(LLDBLog::Expressions); |
| |
| llvm::Function *function = M.getFunction(StringRef(m_func_name)); |
| |
| if (!function) { |
| LLDB_LOGF(log, "Couldn't find %s() in the module", m_func_name.c_str()); |
| |
| return false; |
| } |
| |
| if (m_checker_functions.m_valid_pointer_check) { |
| ValidPointerChecker vpc(M, m_checker_functions.m_valid_pointer_check); |
| |
| if (!vpc.Inspect(*function)) |
| return false; |
| |
| if (!vpc.Instrument()) |
| return false; |
| } |
| |
| if (m_checker_functions.m_objc_object_check) { |
| ObjcObjectChecker ooc(M, m_checker_functions.m_objc_object_check); |
| |
| if (!ooc.Inspect(*function)) |
| return false; |
| |
| if (!ooc.Instrument()) |
| return false; |
| } |
| |
| if (log && log->GetVerbose()) { |
| std::string s; |
| raw_string_ostream oss(s); |
| |
| M.print(oss, nullptr); |
| |
| oss.flush(); |
| |
| LLDB_LOGF(log, "Module after dynamic checks: \n%s", s.c_str()); |
| } |
| |
| return true; |
| } |
| |
| void IRDynamicChecks::assignPassManager(PMStack &PMS, PassManagerType T) {} |
| |
| PassManagerType IRDynamicChecks::getPotentialPassManagerType() const { |
| return PMT_ModulePassManager; |
| } |