1//===-- DataFlowSanitizer.cpp - dynamic data flow analysis ----------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9/// \file 10/// This file is a part of DataFlowSanitizer, a generalised dynamic data flow 11/// analysis. 12/// 13/// Unlike other Sanitizer tools, this tool is not designed to detect a specific 14/// class of bugs on its own. Instead, it provides a generic dynamic data flow 15/// analysis framework to be used by clients to help detect application-specific 16/// issues within their own code. 17/// 18/// The analysis is based on automatic propagation of data flow labels (also 19/// known as taint labels) through a program as it performs computation. Each 20/// byte of application memory is backed by two bytes of shadow memory which 21/// hold the label. On Linux/x86_64, memory is laid out as follows: 22/// 23/// +--------------------+ 0x800000000000 (top of memory) 24/// | application memory | 25/// +--------------------+ 0x700000008000 (kAppAddr) 26/// | | 27/// | unused | 28/// | | 29/// +--------------------+ 0x200200000000 (kUnusedAddr) 30/// | union table | 31/// +--------------------+ 0x200000000000 (kUnionTableAddr) 32/// | shadow memory | 33/// +--------------------+ 0x000000010000 (kShadowAddr) 34/// | reserved by kernel | 35/// +--------------------+ 0x000000000000 36/// 37/// To derive a shadow memory address from an application memory address, 38/// bits 44-46 are cleared to bring the address into the range 39/// [0x000000008000,0x100000000000). Then the address is shifted left by 1 to 40/// account for the double byte representation of shadow labels and move the 41/// address into the shadow memory range. See the function 42/// DataFlowSanitizer::getShadowAddress below. 43/// 44/// For more information, please refer to the design document: 45/// http://clang.llvm.org/docs/DataFlowSanitizerDesign.html 46 47#include "llvm/Transforms/Instrumentation.h" 48#include "llvm/ADT/DenseMap.h" 49#include "llvm/ADT/DenseSet.h" 50#include "llvm/ADT/DepthFirstIterator.h" 51#include "llvm/ADT/StringExtras.h" 52#include "llvm/Analysis/ValueTracking.h" 53#include "llvm/IR/IRBuilder.h" 54#include "llvm/IR/InlineAsm.h" 55#include "llvm/IR/InstVisitor.h" 56#include "llvm/IR/LLVMContext.h" 57#include "llvm/IR/MDBuilder.h" 58#include "llvm/IR/Type.h" 59#include "llvm/IR/Value.h" 60#include "llvm/Pass.h" 61#include "llvm/Support/CommandLine.h" 62#include "llvm/Support/SpecialCaseList.h" 63#include "llvm/Transforms/Utils/BasicBlockUtils.h" 64#include "llvm/Transforms/Utils/Local.h" 65#include <iterator> 66 67using namespace llvm; 68 69// The -dfsan-preserve-alignment flag controls whether this pass assumes that 70// alignment requirements provided by the input IR are correct. For example, 71// if the input IR contains a load with alignment 8, this flag will cause 72// the shadow load to have alignment 16. This flag is disabled by default as 73// we have unfortunately encountered too much code (including Clang itself; 74// see PR14291) which performs misaligned access. 75static cl::opt<bool> ClPreserveAlignment( 76 "dfsan-preserve-alignment", 77 cl::desc("respect alignment requirements provided by input IR"), cl::Hidden, 78 cl::init(false)); 79 80// The ABI list file controls how shadow parameters are passed. The pass treats 81// every function labelled "uninstrumented" in the ABI list file as conforming 82// to the "native" (i.e. unsanitized) ABI. Unless the ABI list contains 83// additional annotations for those functions, a call to one of those functions 84// will produce a warning message, as the labelling behaviour of the function is 85// unknown. The other supported annotations are "functional" and "discard", 86// which are described below under DataFlowSanitizer::WrapperKind. 87static cl::opt<std::string> ClABIListFile( 88 "dfsan-abilist", 89 cl::desc("File listing native ABI functions and how the pass treats them"), 90 cl::Hidden); 91 92// Controls whether the pass uses IA_Args or IA_TLS as the ABI for instrumented 93// functions (see DataFlowSanitizer::InstrumentedABI below). 94static cl::opt<bool> ClArgsABI( 95 "dfsan-args-abi", 96 cl::desc("Use the argument ABI rather than the TLS ABI"), 97 cl::Hidden); 98 99// Controls whether the pass includes or ignores the labels of pointers in load 100// instructions. 101static cl::opt<bool> ClCombinePointerLabelsOnLoad( 102 "dfsan-combine-pointer-labels-on-load", 103 cl::desc("Combine the label of the pointer with the label of the data when " 104 "loading from memory."), 105 cl::Hidden, cl::init(true)); 106 107// Controls whether the pass includes or ignores the labels of pointers in 108// stores instructions. 109static cl::opt<bool> ClCombinePointerLabelsOnStore( 110 "dfsan-combine-pointer-labels-on-store", 111 cl::desc("Combine the label of the pointer with the label of the data when " 112 "storing in memory."), 113 cl::Hidden, cl::init(false)); 114 115static cl::opt<bool> ClDebugNonzeroLabels( 116 "dfsan-debug-nonzero-labels", 117 cl::desc("Insert calls to __dfsan_nonzero_label on observing a parameter, " 118 "load or return with a nonzero label"), 119 cl::Hidden); 120 121namespace { 122 123StringRef GetGlobalTypeString(const GlobalValue &G) { 124 // Types of GlobalVariables are always pointer types. 125 Type *GType = G.getType()->getElementType(); 126 // For now we support blacklisting struct types only. 127 if (StructType *SGType = dyn_cast<StructType>(GType)) { 128 if (!SGType->isLiteral()) 129 return SGType->getName(); 130 } 131 return "<unknown type>"; 132} 133 134class DFSanABIList { 135 std::unique_ptr<SpecialCaseList> SCL; 136 137 public: 138 DFSanABIList(SpecialCaseList *SCL) : SCL(SCL) {} 139 140 /// Returns whether either this function or its source file are listed in the 141 /// given category. 142 bool isIn(const Function &F, const StringRef Category) const { 143 return isIn(*F.getParent(), Category) || 144 SCL->inSection("fun", F.getName(), Category); 145 } 146 147 /// Returns whether this global alias is listed in the given category. 148 /// 149 /// If GA aliases a function, the alias's name is matched as a function name 150 /// would be. Similarly, aliases of globals are matched like globals. 151 bool isIn(const GlobalAlias &GA, const StringRef Category) const { 152 if (isIn(*GA.getParent(), Category)) 153 return true; 154 155 if (isa<FunctionType>(GA.getType()->getElementType())) 156 return SCL->inSection("fun", GA.getName(), Category); 157 158 return SCL->inSection("global", GA.getName(), Category) || 159 SCL->inSection("type", GetGlobalTypeString(GA), Category); 160 } 161 162 /// Returns whether this module is listed in the given category. 163 bool isIn(const Module &M, const StringRef Category) const { 164 return SCL->inSection("src", M.getModuleIdentifier(), Category); 165 } 166}; 167 168class DataFlowSanitizer : public ModulePass { 169 friend struct DFSanFunction; 170 friend class DFSanVisitor; 171 172 enum { 173 ShadowWidth = 16 174 }; 175 176 /// Which ABI should be used for instrumented functions? 177 enum InstrumentedABI { 178 /// Argument and return value labels are passed through additional 179 /// arguments and by modifying the return type. 180 IA_Args, 181 182 /// Argument and return value labels are passed through TLS variables 183 /// __dfsan_arg_tls and __dfsan_retval_tls. 184 IA_TLS 185 }; 186 187 /// How should calls to uninstrumented functions be handled? 188 enum WrapperKind { 189 /// This function is present in an uninstrumented form but we don't know 190 /// how it should be handled. Print a warning and call the function anyway. 191 /// Don't label the return value. 192 WK_Warning, 193 194 /// This function does not write to (user-accessible) memory, and its return 195 /// value is unlabelled. 196 WK_Discard, 197 198 /// This function does not write to (user-accessible) memory, and the label 199 /// of its return value is the union of the label of its arguments. 200 WK_Functional, 201 202 /// Instead of calling the function, a custom wrapper __dfsw_F is called, 203 /// where F is the name of the function. This function may wrap the 204 /// original function or provide its own implementation. This is similar to 205 /// the IA_Args ABI, except that IA_Args uses a struct return type to 206 /// pass the return value shadow in a register, while WK_Custom uses an 207 /// extra pointer argument to return the shadow. This allows the wrapped 208 /// form of the function type to be expressed in C. 209 WK_Custom 210 }; 211 212 const DataLayout *DL; 213 Module *Mod; 214 LLVMContext *Ctx; 215 IntegerType *ShadowTy; 216 PointerType *ShadowPtrTy; 217 IntegerType *IntptrTy; 218 ConstantInt *ZeroShadow; 219 ConstantInt *ShadowPtrMask; 220 ConstantInt *ShadowPtrMul; 221 Constant *ArgTLS; 222 Constant *RetvalTLS; 223 void *(*GetArgTLSPtr)(); 224 void *(*GetRetvalTLSPtr)(); 225 Constant *GetArgTLS; 226 Constant *GetRetvalTLS; 227 FunctionType *DFSanUnionFnTy; 228 FunctionType *DFSanUnionLoadFnTy; 229 FunctionType *DFSanUnimplementedFnTy; 230 FunctionType *DFSanSetLabelFnTy; 231 FunctionType *DFSanNonzeroLabelFnTy; 232 Constant *DFSanUnionFn; 233 Constant *DFSanUnionLoadFn; 234 Constant *DFSanUnimplementedFn; 235 Constant *DFSanSetLabelFn; 236 Constant *DFSanNonzeroLabelFn; 237 MDNode *ColdCallWeights; 238 DFSanABIList ABIList; 239 DenseMap<Value *, Function *> UnwrappedFnMap; 240 AttributeSet ReadOnlyNoneAttrs; 241 242 Value *getShadowAddress(Value *Addr, Instruction *Pos); 243 Value *combineShadows(Value *V1, Value *V2, Instruction *Pos); 244 bool isInstrumented(const Function *F); 245 bool isInstrumented(const GlobalAlias *GA); 246 FunctionType *getArgsFunctionType(FunctionType *T); 247 FunctionType *getTrampolineFunctionType(FunctionType *T); 248 FunctionType *getCustomFunctionType(FunctionType *T); 249 InstrumentedABI getInstrumentedABI(); 250 WrapperKind getWrapperKind(Function *F); 251 void addGlobalNamePrefix(GlobalValue *GV); 252 Function *buildWrapperFunction(Function *F, StringRef NewFName, 253 GlobalValue::LinkageTypes NewFLink, 254 FunctionType *NewFT); 255 Constant *getOrBuildTrampolineFunction(FunctionType *FT, StringRef FName); 256 257 public: 258 DataFlowSanitizer(StringRef ABIListFile = StringRef(), 259 void *(*getArgTLS)() = nullptr, 260 void *(*getRetValTLS)() = nullptr); 261 static char ID; 262 bool doInitialization(Module &M) override; 263 bool runOnModule(Module &M) override; 264}; 265 266struct DFSanFunction { 267 DataFlowSanitizer &DFS; 268 Function *F; 269 DataFlowSanitizer::InstrumentedABI IA; 270 bool IsNativeABI; 271 Value *ArgTLSPtr; 272 Value *RetvalTLSPtr; 273 AllocaInst *LabelReturnAlloca; 274 DenseMap<Value *, Value *> ValShadowMap; 275 DenseMap<AllocaInst *, AllocaInst *> AllocaShadowMap; 276 std::vector<std::pair<PHINode *, PHINode *> > PHIFixups; 277 DenseSet<Instruction *> SkipInsts; 278 DenseSet<Value *> NonZeroChecks; 279 280 DFSanFunction(DataFlowSanitizer &DFS, Function *F, bool IsNativeABI) 281 : DFS(DFS), F(F), IA(DFS.getInstrumentedABI()), 282 IsNativeABI(IsNativeABI), ArgTLSPtr(nullptr), RetvalTLSPtr(nullptr), 283 LabelReturnAlloca(nullptr) {} 284 Value *getArgTLSPtr(); 285 Value *getArgTLS(unsigned Index, Instruction *Pos); 286 Value *getRetvalTLS(); 287 Value *getShadow(Value *V); 288 void setShadow(Instruction *I, Value *Shadow); 289 Value *combineOperandShadows(Instruction *Inst); 290 Value *loadShadow(Value *ShadowAddr, uint64_t Size, uint64_t Align, 291 Instruction *Pos); 292 void storeShadow(Value *Addr, uint64_t Size, uint64_t Align, Value *Shadow, 293 Instruction *Pos); 294}; 295 296class DFSanVisitor : public InstVisitor<DFSanVisitor> { 297 public: 298 DFSanFunction &DFSF; 299 DFSanVisitor(DFSanFunction &DFSF) : DFSF(DFSF) {} 300 301 void visitOperandShadowInst(Instruction &I); 302 303 void visitBinaryOperator(BinaryOperator &BO); 304 void visitCastInst(CastInst &CI); 305 void visitCmpInst(CmpInst &CI); 306 void visitGetElementPtrInst(GetElementPtrInst &GEPI); 307 void visitLoadInst(LoadInst &LI); 308 void visitStoreInst(StoreInst &SI); 309 void visitReturnInst(ReturnInst &RI); 310 void visitCallSite(CallSite CS); 311 void visitPHINode(PHINode &PN); 312 void visitExtractElementInst(ExtractElementInst &I); 313 void visitInsertElementInst(InsertElementInst &I); 314 void visitShuffleVectorInst(ShuffleVectorInst &I); 315 void visitExtractValueInst(ExtractValueInst &I); 316 void visitInsertValueInst(InsertValueInst &I); 317 void visitAllocaInst(AllocaInst &I); 318 void visitSelectInst(SelectInst &I); 319 void visitMemSetInst(MemSetInst &I); 320 void visitMemTransferInst(MemTransferInst &I); 321}; 322 323} 324 325char DataFlowSanitizer::ID; 326INITIALIZE_PASS(DataFlowSanitizer, "dfsan", 327 "DataFlowSanitizer: dynamic data flow analysis.", false, false) 328 329ModulePass *llvm::createDataFlowSanitizerPass(StringRef ABIListFile, 330 void *(*getArgTLS)(), 331 void *(*getRetValTLS)()) { 332 return new DataFlowSanitizer(ABIListFile, getArgTLS, getRetValTLS); 333} 334 335DataFlowSanitizer::DataFlowSanitizer(StringRef ABIListFile, 336 void *(*getArgTLS)(), 337 void *(*getRetValTLS)()) 338 : ModulePass(ID), GetArgTLSPtr(getArgTLS), GetRetvalTLSPtr(getRetValTLS), 339 ABIList(SpecialCaseList::createOrDie(ABIListFile.empty() ? ClABIListFile 340 : ABIListFile)) { 341} 342 343FunctionType *DataFlowSanitizer::getArgsFunctionType(FunctionType *T) { 344 llvm::SmallVector<Type *, 4> ArgTypes; 345 std::copy(T->param_begin(), T->param_end(), std::back_inserter(ArgTypes)); 346 for (unsigned i = 0, e = T->getNumParams(); i != e; ++i) 347 ArgTypes.push_back(ShadowTy); 348 if (T->isVarArg()) 349 ArgTypes.push_back(ShadowPtrTy); 350 Type *RetType = T->getReturnType(); 351 if (!RetType->isVoidTy()) 352 RetType = StructType::get(RetType, ShadowTy, (Type *)nullptr); 353 return FunctionType::get(RetType, ArgTypes, T->isVarArg()); 354} 355 356FunctionType *DataFlowSanitizer::getTrampolineFunctionType(FunctionType *T) { 357 assert(!T->isVarArg()); 358 llvm::SmallVector<Type *, 4> ArgTypes; 359 ArgTypes.push_back(T->getPointerTo()); 360 std::copy(T->param_begin(), T->param_end(), std::back_inserter(ArgTypes)); 361 for (unsigned i = 0, e = T->getNumParams(); i != e; ++i) 362 ArgTypes.push_back(ShadowTy); 363 Type *RetType = T->getReturnType(); 364 if (!RetType->isVoidTy()) 365 ArgTypes.push_back(ShadowPtrTy); 366 return FunctionType::get(T->getReturnType(), ArgTypes, false); 367} 368 369FunctionType *DataFlowSanitizer::getCustomFunctionType(FunctionType *T) { 370 assert(!T->isVarArg()); 371 llvm::SmallVector<Type *, 4> ArgTypes; 372 for (FunctionType::param_iterator i = T->param_begin(), e = T->param_end(); 373 i != e; ++i) { 374 FunctionType *FT; 375 if (isa<PointerType>(*i) && (FT = dyn_cast<FunctionType>(cast<PointerType>( 376 *i)->getElementType()))) { 377 ArgTypes.push_back(getTrampolineFunctionType(FT)->getPointerTo()); 378 ArgTypes.push_back(Type::getInt8PtrTy(*Ctx)); 379 } else { 380 ArgTypes.push_back(*i); 381 } 382 } 383 for (unsigned i = 0, e = T->getNumParams(); i != e; ++i) 384 ArgTypes.push_back(ShadowTy); 385 Type *RetType = T->getReturnType(); 386 if (!RetType->isVoidTy()) 387 ArgTypes.push_back(ShadowPtrTy); 388 return FunctionType::get(T->getReturnType(), ArgTypes, false); 389} 390 391bool DataFlowSanitizer::doInitialization(Module &M) { 392 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); 393 if (!DLP) 394 report_fatal_error("data layout missing"); 395 DL = &DLP->getDataLayout(); 396 397 Mod = &M; 398 Ctx = &M.getContext(); 399 ShadowTy = IntegerType::get(*Ctx, ShadowWidth); 400 ShadowPtrTy = PointerType::getUnqual(ShadowTy); 401 IntptrTy = DL->getIntPtrType(*Ctx); 402 ZeroShadow = ConstantInt::getSigned(ShadowTy, 0); 403 ShadowPtrMask = ConstantInt::getSigned(IntptrTy, ~0x700000000000LL); 404 ShadowPtrMul = ConstantInt::getSigned(IntptrTy, ShadowWidth / 8); 405 406 Type *DFSanUnionArgs[2] = { ShadowTy, ShadowTy }; 407 DFSanUnionFnTy = 408 FunctionType::get(ShadowTy, DFSanUnionArgs, /*isVarArg=*/ false); 409 Type *DFSanUnionLoadArgs[2] = { ShadowPtrTy, IntptrTy }; 410 DFSanUnionLoadFnTy = 411 FunctionType::get(ShadowTy, DFSanUnionLoadArgs, /*isVarArg=*/ false); 412 DFSanUnimplementedFnTy = FunctionType::get( 413 Type::getVoidTy(*Ctx), Type::getInt8PtrTy(*Ctx), /*isVarArg=*/false); 414 Type *DFSanSetLabelArgs[3] = { ShadowTy, Type::getInt8PtrTy(*Ctx), IntptrTy }; 415 DFSanSetLabelFnTy = FunctionType::get(Type::getVoidTy(*Ctx), 416 DFSanSetLabelArgs, /*isVarArg=*/false); 417 DFSanNonzeroLabelFnTy = FunctionType::get( 418 Type::getVoidTy(*Ctx), ArrayRef<Type *>(), /*isVarArg=*/false); 419 420 if (GetArgTLSPtr) { 421 Type *ArgTLSTy = ArrayType::get(ShadowTy, 64); 422 ArgTLS = nullptr; 423 GetArgTLS = ConstantExpr::getIntToPtr( 424 ConstantInt::get(IntptrTy, uintptr_t(GetArgTLSPtr)), 425 PointerType::getUnqual( 426 FunctionType::get(PointerType::getUnqual(ArgTLSTy), 427 (Type *)nullptr))); 428 } 429 if (GetRetvalTLSPtr) { 430 RetvalTLS = nullptr; 431 GetRetvalTLS = ConstantExpr::getIntToPtr( 432 ConstantInt::get(IntptrTy, uintptr_t(GetRetvalTLSPtr)), 433 PointerType::getUnqual( 434 FunctionType::get(PointerType::getUnqual(ShadowTy), 435 (Type *)nullptr))); 436 } 437 438 ColdCallWeights = MDBuilder(*Ctx).createBranchWeights(1, 1000); 439 return true; 440} 441 442bool DataFlowSanitizer::isInstrumented(const Function *F) { 443 return !ABIList.isIn(*F, "uninstrumented"); 444} 445 446bool DataFlowSanitizer::isInstrumented(const GlobalAlias *GA) { 447 return !ABIList.isIn(*GA, "uninstrumented"); 448} 449 450DataFlowSanitizer::InstrumentedABI DataFlowSanitizer::getInstrumentedABI() { 451 return ClArgsABI ? IA_Args : IA_TLS; 452} 453 454DataFlowSanitizer::WrapperKind DataFlowSanitizer::getWrapperKind(Function *F) { 455 if (ABIList.isIn(*F, "functional")) 456 return WK_Functional; 457 if (ABIList.isIn(*F, "discard")) 458 return WK_Discard; 459 if (ABIList.isIn(*F, "custom")) 460 return WK_Custom; 461 462 return WK_Warning; 463} 464 465void DataFlowSanitizer::addGlobalNamePrefix(GlobalValue *GV) { 466 std::string GVName = GV->getName(), Prefix = "dfs$"; 467 GV->setName(Prefix + GVName); 468 469 // Try to change the name of the function in module inline asm. We only do 470 // this for specific asm directives, currently only ".symver", to try to avoid 471 // corrupting asm which happens to contain the symbol name as a substring. 472 // Note that the substitution for .symver assumes that the versioned symbol 473 // also has an instrumented name. 474 std::string Asm = GV->getParent()->getModuleInlineAsm(); 475 std::string SearchStr = ".symver " + GVName + ","; 476 size_t Pos = Asm.find(SearchStr); 477 if (Pos != std::string::npos) { 478 Asm.replace(Pos, SearchStr.size(), 479 ".symver " + Prefix + GVName + "," + Prefix); 480 GV->getParent()->setModuleInlineAsm(Asm); 481 } 482} 483 484Function * 485DataFlowSanitizer::buildWrapperFunction(Function *F, StringRef NewFName, 486 GlobalValue::LinkageTypes NewFLink, 487 FunctionType *NewFT) { 488 FunctionType *FT = F->getFunctionType(); 489 Function *NewF = Function::Create(NewFT, NewFLink, NewFName, 490 F->getParent()); 491 NewF->copyAttributesFrom(F); 492 NewF->removeAttributes( 493 AttributeSet::ReturnIndex, 494 AttributeFuncs::typeIncompatible(NewFT->getReturnType(), 495 AttributeSet::ReturnIndex)); 496 497 BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", NewF); 498 std::vector<Value *> Args; 499 unsigned n = FT->getNumParams(); 500 for (Function::arg_iterator ai = NewF->arg_begin(); n != 0; ++ai, --n) 501 Args.push_back(&*ai); 502 CallInst *CI = CallInst::Create(F, Args, "", BB); 503 if (FT->getReturnType()->isVoidTy()) 504 ReturnInst::Create(*Ctx, BB); 505 else 506 ReturnInst::Create(*Ctx, CI, BB); 507 508 return NewF; 509} 510 511Constant *DataFlowSanitizer::getOrBuildTrampolineFunction(FunctionType *FT, 512 StringRef FName) { 513 FunctionType *FTT = getTrampolineFunctionType(FT); 514 Constant *C = Mod->getOrInsertFunction(FName, FTT); 515 Function *F = dyn_cast<Function>(C); 516 if (F && F->isDeclaration()) { 517 F->setLinkage(GlobalValue::LinkOnceODRLinkage); 518 BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", F); 519 std::vector<Value *> Args; 520 Function::arg_iterator AI = F->arg_begin(); ++AI; 521 for (unsigned N = FT->getNumParams(); N != 0; ++AI, --N) 522 Args.push_back(&*AI); 523 CallInst *CI = 524 CallInst::Create(&F->getArgumentList().front(), Args, "", BB); 525 ReturnInst *RI; 526 if (FT->getReturnType()->isVoidTy()) 527 RI = ReturnInst::Create(*Ctx, BB); 528 else 529 RI = ReturnInst::Create(*Ctx, CI, BB); 530 531 DFSanFunction DFSF(*this, F, /*IsNativeABI=*/true); 532 Function::arg_iterator ValAI = F->arg_begin(), ShadowAI = AI; ++ValAI; 533 for (unsigned N = FT->getNumParams(); N != 0; ++ValAI, ++ShadowAI, --N) 534 DFSF.ValShadowMap[ValAI] = ShadowAI; 535 DFSanVisitor(DFSF).visitCallInst(*CI); 536 if (!FT->getReturnType()->isVoidTy()) 537 new StoreInst(DFSF.getShadow(RI->getReturnValue()), 538 &F->getArgumentList().back(), RI); 539 } 540 541 return C; 542} 543 544bool DataFlowSanitizer::runOnModule(Module &M) { 545 if (!DL) 546 return false; 547 548 if (ABIList.isIn(M, "skip")) 549 return false; 550 551 if (!GetArgTLSPtr) { 552 Type *ArgTLSTy = ArrayType::get(ShadowTy, 64); 553 ArgTLS = Mod->getOrInsertGlobal("__dfsan_arg_tls", ArgTLSTy); 554 if (GlobalVariable *G = dyn_cast<GlobalVariable>(ArgTLS)) 555 G->setThreadLocalMode(GlobalVariable::InitialExecTLSModel); 556 } 557 if (!GetRetvalTLSPtr) { 558 RetvalTLS = Mod->getOrInsertGlobal("__dfsan_retval_tls", ShadowTy); 559 if (GlobalVariable *G = dyn_cast<GlobalVariable>(RetvalTLS)) 560 G->setThreadLocalMode(GlobalVariable::InitialExecTLSModel); 561 } 562 563 DFSanUnionFn = Mod->getOrInsertFunction("__dfsan_union", DFSanUnionFnTy); 564 if (Function *F = dyn_cast<Function>(DFSanUnionFn)) { 565 F->addAttribute(AttributeSet::FunctionIndex, Attribute::ReadNone); 566 F->addAttribute(AttributeSet::ReturnIndex, Attribute::ZExt); 567 F->addAttribute(1, Attribute::ZExt); 568 F->addAttribute(2, Attribute::ZExt); 569 } 570 DFSanUnionLoadFn = 571 Mod->getOrInsertFunction("__dfsan_union_load", DFSanUnionLoadFnTy); 572 if (Function *F = dyn_cast<Function>(DFSanUnionLoadFn)) { 573 F->addAttribute(AttributeSet::FunctionIndex, Attribute::ReadOnly); 574 F->addAttribute(AttributeSet::ReturnIndex, Attribute::ZExt); 575 } 576 DFSanUnimplementedFn = 577 Mod->getOrInsertFunction("__dfsan_unimplemented", DFSanUnimplementedFnTy); 578 DFSanSetLabelFn = 579 Mod->getOrInsertFunction("__dfsan_set_label", DFSanSetLabelFnTy); 580 if (Function *F = dyn_cast<Function>(DFSanSetLabelFn)) { 581 F->addAttribute(1, Attribute::ZExt); 582 } 583 DFSanNonzeroLabelFn = 584 Mod->getOrInsertFunction("__dfsan_nonzero_label", DFSanNonzeroLabelFnTy); 585 586 std::vector<Function *> FnsToInstrument; 587 llvm::SmallPtrSet<Function *, 2> FnsWithNativeABI; 588 for (Module::iterator i = M.begin(), e = M.end(); i != e; ++i) { 589 if (!i->isIntrinsic() && 590 i != DFSanUnionFn && 591 i != DFSanUnionLoadFn && 592 i != DFSanUnimplementedFn && 593 i != DFSanSetLabelFn && 594 i != DFSanNonzeroLabelFn) 595 FnsToInstrument.push_back(&*i); 596 } 597 598 // Give function aliases prefixes when necessary, and build wrappers where the 599 // instrumentedness is inconsistent. 600 for (Module::alias_iterator i = M.alias_begin(), e = M.alias_end(); i != e;) { 601 GlobalAlias *GA = &*i; 602 ++i; 603 // Don't stop on weak. We assume people aren't playing games with the 604 // instrumentedness of overridden weak aliases. 605 if (auto F = dyn_cast<Function>(GA->getBaseObject())) { 606 bool GAInst = isInstrumented(GA), FInst = isInstrumented(F); 607 if (GAInst && FInst) { 608 addGlobalNamePrefix(GA); 609 } else if (GAInst != FInst) { 610 // Non-instrumented alias of an instrumented function, or vice versa. 611 // Replace the alias with a native-ABI wrapper of the aliasee. The pass 612 // below will take care of instrumenting it. 613 Function *NewF = 614 buildWrapperFunction(F, "", GA->getLinkage(), F->getFunctionType()); 615 GA->replaceAllUsesWith(ConstantExpr::getBitCast(NewF, GA->getType())); 616 NewF->takeName(GA); 617 GA->eraseFromParent(); 618 FnsToInstrument.push_back(NewF); 619 } 620 } 621 } 622 623 AttrBuilder B; 624 B.addAttribute(Attribute::ReadOnly).addAttribute(Attribute::ReadNone); 625 ReadOnlyNoneAttrs = AttributeSet::get(*Ctx, AttributeSet::FunctionIndex, B); 626 627 // First, change the ABI of every function in the module. ABI-listed 628 // functions keep their original ABI and get a wrapper function. 629 for (std::vector<Function *>::iterator i = FnsToInstrument.begin(), 630 e = FnsToInstrument.end(); 631 i != e; ++i) { 632 Function &F = **i; 633 FunctionType *FT = F.getFunctionType(); 634 635 bool IsZeroArgsVoidRet = (FT->getNumParams() == 0 && !FT->isVarArg() && 636 FT->getReturnType()->isVoidTy()); 637 638 if (isInstrumented(&F)) { 639 // Instrumented functions get a 'dfs$' prefix. This allows us to more 640 // easily identify cases of mismatching ABIs. 641 if (getInstrumentedABI() == IA_Args && !IsZeroArgsVoidRet) { 642 FunctionType *NewFT = getArgsFunctionType(FT); 643 Function *NewF = Function::Create(NewFT, F.getLinkage(), "", &M); 644 NewF->copyAttributesFrom(&F); 645 NewF->removeAttributes( 646 AttributeSet::ReturnIndex, 647 AttributeFuncs::typeIncompatible(NewFT->getReturnType(), 648 AttributeSet::ReturnIndex)); 649 for (Function::arg_iterator FArg = F.arg_begin(), 650 NewFArg = NewF->arg_begin(), 651 FArgEnd = F.arg_end(); 652 FArg != FArgEnd; ++FArg, ++NewFArg) { 653 FArg->replaceAllUsesWith(NewFArg); 654 } 655 NewF->getBasicBlockList().splice(NewF->begin(), F.getBasicBlockList()); 656 657 for (Function::user_iterator UI = F.user_begin(), UE = F.user_end(); 658 UI != UE;) { 659 BlockAddress *BA = dyn_cast<BlockAddress>(*UI); 660 ++UI; 661 if (BA) { 662 BA->replaceAllUsesWith( 663 BlockAddress::get(NewF, BA->getBasicBlock())); 664 delete BA; 665 } 666 } 667 F.replaceAllUsesWith( 668 ConstantExpr::getBitCast(NewF, PointerType::getUnqual(FT))); 669 NewF->takeName(&F); 670 F.eraseFromParent(); 671 *i = NewF; 672 addGlobalNamePrefix(NewF); 673 } else { 674 addGlobalNamePrefix(&F); 675 } 676 // Hopefully, nobody will try to indirectly call a vararg 677 // function... yet. 678 } else if (FT->isVarArg()) { 679 UnwrappedFnMap[&F] = &F; 680 *i = nullptr; 681 } else if (!IsZeroArgsVoidRet || getWrapperKind(&F) == WK_Custom) { 682 // Build a wrapper function for F. The wrapper simply calls F, and is 683 // added to FnsToInstrument so that any instrumentation according to its 684 // WrapperKind is done in the second pass below. 685 FunctionType *NewFT = getInstrumentedABI() == IA_Args 686 ? getArgsFunctionType(FT) 687 : FT; 688 Function *NewF = buildWrapperFunction( 689 &F, std::string("dfsw$") + std::string(F.getName()), 690 GlobalValue::LinkOnceODRLinkage, NewFT); 691 if (getInstrumentedABI() == IA_TLS) 692 NewF->removeAttributes(AttributeSet::FunctionIndex, ReadOnlyNoneAttrs); 693 694 Value *WrappedFnCst = 695 ConstantExpr::getBitCast(NewF, PointerType::getUnqual(FT)); 696 F.replaceAllUsesWith(WrappedFnCst); 697 UnwrappedFnMap[WrappedFnCst] = &F; 698 *i = NewF; 699 700 if (!F.isDeclaration()) { 701 // This function is probably defining an interposition of an 702 // uninstrumented function and hence needs to keep the original ABI. 703 // But any functions it may call need to use the instrumented ABI, so 704 // we instrument it in a mode which preserves the original ABI. 705 FnsWithNativeABI.insert(&F); 706 707 // This code needs to rebuild the iterators, as they may be invalidated 708 // by the push_back, taking care that the new range does not include 709 // any functions added by this code. 710 size_t N = i - FnsToInstrument.begin(), 711 Count = e - FnsToInstrument.begin(); 712 FnsToInstrument.push_back(&F); 713 i = FnsToInstrument.begin() + N; 714 e = FnsToInstrument.begin() + Count; 715 } 716 } 717 } 718 719 for (std::vector<Function *>::iterator i = FnsToInstrument.begin(), 720 e = FnsToInstrument.end(); 721 i != e; ++i) { 722 if (!*i || (*i)->isDeclaration()) 723 continue; 724 725 removeUnreachableBlocks(**i); 726 727 DFSanFunction DFSF(*this, *i, FnsWithNativeABI.count(*i)); 728 729 // DFSanVisitor may create new basic blocks, which confuses df_iterator. 730 // Build a copy of the list before iterating over it. 731 llvm::SmallVector<BasicBlock *, 4> BBList( 732 depth_first(&(*i)->getEntryBlock())); 733 734 for (llvm::SmallVector<BasicBlock *, 4>::iterator i = BBList.begin(), 735 e = BBList.end(); 736 i != e; ++i) { 737 Instruction *Inst = &(*i)->front(); 738 while (1) { 739 // DFSanVisitor may split the current basic block, changing the current 740 // instruction's next pointer and moving the next instruction to the 741 // tail block from which we should continue. 742 Instruction *Next = Inst->getNextNode(); 743 // DFSanVisitor may delete Inst, so keep track of whether it was a 744 // terminator. 745 bool IsTerminator = isa<TerminatorInst>(Inst); 746 if (!DFSF.SkipInsts.count(Inst)) 747 DFSanVisitor(DFSF).visit(Inst); 748 if (IsTerminator) 749 break; 750 Inst = Next; 751 } 752 } 753 754 // We will not necessarily be able to compute the shadow for every phi node 755 // until we have visited every block. Therefore, the code that handles phi 756 // nodes adds them to the PHIFixups list so that they can be properly 757 // handled here. 758 for (std::vector<std::pair<PHINode *, PHINode *> >::iterator 759 i = DFSF.PHIFixups.begin(), 760 e = DFSF.PHIFixups.end(); 761 i != e; ++i) { 762 for (unsigned val = 0, n = i->first->getNumIncomingValues(); val != n; 763 ++val) { 764 i->second->setIncomingValue( 765 val, DFSF.getShadow(i->first->getIncomingValue(val))); 766 } 767 } 768 769 // -dfsan-debug-nonzero-labels will split the CFG in all kinds of crazy 770 // places (i.e. instructions in basic blocks we haven't even begun visiting 771 // yet). To make our life easier, do this work in a pass after the main 772 // instrumentation. 773 if (ClDebugNonzeroLabels) { 774 for (DenseSet<Value *>::iterator i = DFSF.NonZeroChecks.begin(), 775 e = DFSF.NonZeroChecks.end(); 776 i != e; ++i) { 777 Instruction *Pos; 778 if (Instruction *I = dyn_cast<Instruction>(*i)) 779 Pos = I->getNextNode(); 780 else 781 Pos = DFSF.F->getEntryBlock().begin(); 782 while (isa<PHINode>(Pos) || isa<AllocaInst>(Pos)) 783 Pos = Pos->getNextNode(); 784 IRBuilder<> IRB(Pos); 785 Value *Ne = IRB.CreateICmpNE(*i, DFSF.DFS.ZeroShadow); 786 BranchInst *BI = cast<BranchInst>(SplitBlockAndInsertIfThen( 787 Ne, Pos, /*Unreachable=*/false, ColdCallWeights)); 788 IRBuilder<> ThenIRB(BI); 789 ThenIRB.CreateCall(DFSF.DFS.DFSanNonzeroLabelFn); 790 } 791 } 792 } 793 794 return false; 795} 796 797Value *DFSanFunction::getArgTLSPtr() { 798 if (ArgTLSPtr) 799 return ArgTLSPtr; 800 if (DFS.ArgTLS) 801 return ArgTLSPtr = DFS.ArgTLS; 802 803 IRBuilder<> IRB(F->getEntryBlock().begin()); 804 return ArgTLSPtr = IRB.CreateCall(DFS.GetArgTLS); 805} 806 807Value *DFSanFunction::getRetvalTLS() { 808 if (RetvalTLSPtr) 809 return RetvalTLSPtr; 810 if (DFS.RetvalTLS) 811 return RetvalTLSPtr = DFS.RetvalTLS; 812 813 IRBuilder<> IRB(F->getEntryBlock().begin()); 814 return RetvalTLSPtr = IRB.CreateCall(DFS.GetRetvalTLS); 815} 816 817Value *DFSanFunction::getArgTLS(unsigned Idx, Instruction *Pos) { 818 IRBuilder<> IRB(Pos); 819 return IRB.CreateConstGEP2_64(getArgTLSPtr(), 0, Idx); 820} 821 822Value *DFSanFunction::getShadow(Value *V) { 823 if (!isa<Argument>(V) && !isa<Instruction>(V)) 824 return DFS.ZeroShadow; 825 Value *&Shadow = ValShadowMap[V]; 826 if (!Shadow) { 827 if (Argument *A = dyn_cast<Argument>(V)) { 828 if (IsNativeABI) 829 return DFS.ZeroShadow; 830 switch (IA) { 831 case DataFlowSanitizer::IA_TLS: { 832 Value *ArgTLSPtr = getArgTLSPtr(); 833 Instruction *ArgTLSPos = 834 DFS.ArgTLS ? &*F->getEntryBlock().begin() 835 : cast<Instruction>(ArgTLSPtr)->getNextNode(); 836 IRBuilder<> IRB(ArgTLSPos); 837 Shadow = IRB.CreateLoad(getArgTLS(A->getArgNo(), ArgTLSPos)); 838 break; 839 } 840 case DataFlowSanitizer::IA_Args: { 841 unsigned ArgIdx = A->getArgNo() + F->getArgumentList().size() / 2; 842 Function::arg_iterator i = F->arg_begin(); 843 while (ArgIdx--) 844 ++i; 845 Shadow = i; 846 assert(Shadow->getType() == DFS.ShadowTy); 847 break; 848 } 849 } 850 NonZeroChecks.insert(Shadow); 851 } else { 852 Shadow = DFS.ZeroShadow; 853 } 854 } 855 return Shadow; 856} 857 858void DFSanFunction::setShadow(Instruction *I, Value *Shadow) { 859 assert(!ValShadowMap.count(I)); 860 assert(Shadow->getType() == DFS.ShadowTy); 861 ValShadowMap[I] = Shadow; 862} 863 864Value *DataFlowSanitizer::getShadowAddress(Value *Addr, Instruction *Pos) { 865 assert(Addr != RetvalTLS && "Reinstrumenting?"); 866 IRBuilder<> IRB(Pos); 867 return IRB.CreateIntToPtr( 868 IRB.CreateMul( 869 IRB.CreateAnd(IRB.CreatePtrToInt(Addr, IntptrTy), ShadowPtrMask), 870 ShadowPtrMul), 871 ShadowPtrTy); 872} 873 874// Generates IR to compute the union of the two given shadows, inserting it 875// before Pos. Returns the computed union Value. 876Value *DataFlowSanitizer::combineShadows(Value *V1, Value *V2, 877 Instruction *Pos) { 878 if (V1 == ZeroShadow) 879 return V2; 880 if (V2 == ZeroShadow) 881 return V1; 882 if (V1 == V2) 883 return V1; 884 IRBuilder<> IRB(Pos); 885 BasicBlock *Head = Pos->getParent(); 886 Value *Ne = IRB.CreateICmpNE(V1, V2); 887 BranchInst *BI = cast<BranchInst>(SplitBlockAndInsertIfThen( 888 Ne, Pos, /*Unreachable=*/false, ColdCallWeights)); 889 IRBuilder<> ThenIRB(BI); 890 CallInst *Call = ThenIRB.CreateCall2(DFSanUnionFn, V1, V2); 891 Call->addAttribute(AttributeSet::ReturnIndex, Attribute::ZExt); 892 Call->addAttribute(1, Attribute::ZExt); 893 Call->addAttribute(2, Attribute::ZExt); 894 895 BasicBlock *Tail = BI->getSuccessor(0); 896 PHINode *Phi = PHINode::Create(ShadowTy, 2, "", Tail->begin()); 897 Phi->addIncoming(Call, Call->getParent()); 898 Phi->addIncoming(V1, Head); 899 return Phi; 900} 901 902// A convenience function which folds the shadows of each of the operands 903// of the provided instruction Inst, inserting the IR before Inst. Returns 904// the computed union Value. 905Value *DFSanFunction::combineOperandShadows(Instruction *Inst) { 906 if (Inst->getNumOperands() == 0) 907 return DFS.ZeroShadow; 908 909 Value *Shadow = getShadow(Inst->getOperand(0)); 910 for (unsigned i = 1, n = Inst->getNumOperands(); i != n; ++i) { 911 Shadow = DFS.combineShadows(Shadow, getShadow(Inst->getOperand(i)), Inst); 912 } 913 return Shadow; 914} 915 916void DFSanVisitor::visitOperandShadowInst(Instruction &I) { 917 Value *CombinedShadow = DFSF.combineOperandShadows(&I); 918 DFSF.setShadow(&I, CombinedShadow); 919} 920 921// Generates IR to load shadow corresponding to bytes [Addr, Addr+Size), where 922// Addr has alignment Align, and take the union of each of those shadows. 923Value *DFSanFunction::loadShadow(Value *Addr, uint64_t Size, uint64_t Align, 924 Instruction *Pos) { 925 if (AllocaInst *AI = dyn_cast<AllocaInst>(Addr)) { 926 llvm::DenseMap<AllocaInst *, AllocaInst *>::iterator i = 927 AllocaShadowMap.find(AI); 928 if (i != AllocaShadowMap.end()) { 929 IRBuilder<> IRB(Pos); 930 return IRB.CreateLoad(i->second); 931 } 932 } 933 934 uint64_t ShadowAlign = Align * DFS.ShadowWidth / 8; 935 SmallVector<Value *, 2> Objs; 936 GetUnderlyingObjects(Addr, Objs, DFS.DL); 937 bool AllConstants = true; 938 for (SmallVector<Value *, 2>::iterator i = Objs.begin(), e = Objs.end(); 939 i != e; ++i) { 940 if (isa<Function>(*i) || isa<BlockAddress>(*i)) 941 continue; 942 if (isa<GlobalVariable>(*i) && cast<GlobalVariable>(*i)->isConstant()) 943 continue; 944 945 AllConstants = false; 946 break; 947 } 948 if (AllConstants) 949 return DFS.ZeroShadow; 950 951 Value *ShadowAddr = DFS.getShadowAddress(Addr, Pos); 952 switch (Size) { 953 case 0: 954 return DFS.ZeroShadow; 955 case 1: { 956 LoadInst *LI = new LoadInst(ShadowAddr, "", Pos); 957 LI->setAlignment(ShadowAlign); 958 return LI; 959 } 960 case 2: { 961 IRBuilder<> IRB(Pos); 962 Value *ShadowAddr1 = 963 IRB.CreateGEP(ShadowAddr, ConstantInt::get(DFS.IntptrTy, 1)); 964 return DFS.combineShadows(IRB.CreateAlignedLoad(ShadowAddr, ShadowAlign), 965 IRB.CreateAlignedLoad(ShadowAddr1, ShadowAlign), 966 Pos); 967 } 968 } 969 if (Size % (64 / DFS.ShadowWidth) == 0) { 970 // Fast path for the common case where each byte has identical shadow: load 971 // shadow 64 bits at a time, fall out to a __dfsan_union_load call if any 972 // shadow is non-equal. 973 BasicBlock *FallbackBB = BasicBlock::Create(*DFS.Ctx, "", F); 974 IRBuilder<> FallbackIRB(FallbackBB); 975 CallInst *FallbackCall = FallbackIRB.CreateCall2( 976 DFS.DFSanUnionLoadFn, ShadowAddr, ConstantInt::get(DFS.IntptrTy, Size)); 977 FallbackCall->addAttribute(AttributeSet::ReturnIndex, Attribute::ZExt); 978 979 // Compare each of the shadows stored in the loaded 64 bits to each other, 980 // by computing (WideShadow rotl ShadowWidth) == WideShadow. 981 IRBuilder<> IRB(Pos); 982 Value *WideAddr = 983 IRB.CreateBitCast(ShadowAddr, Type::getInt64PtrTy(*DFS.Ctx)); 984 Value *WideShadow = IRB.CreateAlignedLoad(WideAddr, ShadowAlign); 985 Value *TruncShadow = IRB.CreateTrunc(WideShadow, DFS.ShadowTy); 986 Value *ShlShadow = IRB.CreateShl(WideShadow, DFS.ShadowWidth); 987 Value *ShrShadow = IRB.CreateLShr(WideShadow, 64 - DFS.ShadowWidth); 988 Value *RotShadow = IRB.CreateOr(ShlShadow, ShrShadow); 989 Value *ShadowsEq = IRB.CreateICmpEQ(WideShadow, RotShadow); 990 991 BasicBlock *Head = Pos->getParent(); 992 BasicBlock *Tail = Head->splitBasicBlock(Pos); 993 // In the following code LastBr will refer to the previous basic block's 994 // conditional branch instruction, whose true successor is fixed up to point 995 // to the next block during the loop below or to the tail after the final 996 // iteration. 997 BranchInst *LastBr = BranchInst::Create(FallbackBB, FallbackBB, ShadowsEq); 998 ReplaceInstWithInst(Head->getTerminator(), LastBr); 999 1000 for (uint64_t Ofs = 64 / DFS.ShadowWidth; Ofs != Size; 1001 Ofs += 64 / DFS.ShadowWidth) { 1002 BasicBlock *NextBB = BasicBlock::Create(*DFS.Ctx, "", F); 1003 IRBuilder<> NextIRB(NextBB); 1004 WideAddr = NextIRB.CreateGEP(WideAddr, ConstantInt::get(DFS.IntptrTy, 1)); 1005 Value *NextWideShadow = NextIRB.CreateAlignedLoad(WideAddr, ShadowAlign); 1006 ShadowsEq = NextIRB.CreateICmpEQ(WideShadow, NextWideShadow); 1007 LastBr->setSuccessor(0, NextBB); 1008 LastBr = NextIRB.CreateCondBr(ShadowsEq, FallbackBB, FallbackBB); 1009 } 1010 1011 LastBr->setSuccessor(0, Tail); 1012 FallbackIRB.CreateBr(Tail); 1013 PHINode *Shadow = PHINode::Create(DFS.ShadowTy, 2, "", &Tail->front()); 1014 Shadow->addIncoming(FallbackCall, FallbackBB); 1015 Shadow->addIncoming(TruncShadow, LastBr->getParent()); 1016 return Shadow; 1017 } 1018 1019 IRBuilder<> IRB(Pos); 1020 CallInst *FallbackCall = IRB.CreateCall2( 1021 DFS.DFSanUnionLoadFn, ShadowAddr, ConstantInt::get(DFS.IntptrTy, Size)); 1022 FallbackCall->addAttribute(AttributeSet::ReturnIndex, Attribute::ZExt); 1023 return FallbackCall; 1024} 1025 1026void DFSanVisitor::visitLoadInst(LoadInst &LI) { 1027 uint64_t Size = DFSF.DFS.DL->getTypeStoreSize(LI.getType()); 1028 uint64_t Align; 1029 if (ClPreserveAlignment) { 1030 Align = LI.getAlignment(); 1031 if (Align == 0) 1032 Align = DFSF.DFS.DL->getABITypeAlignment(LI.getType()); 1033 } else { 1034 Align = 1; 1035 } 1036 IRBuilder<> IRB(&LI); 1037 Value *Shadow = DFSF.loadShadow(LI.getPointerOperand(), Size, Align, &LI); 1038 if (ClCombinePointerLabelsOnLoad) { 1039 Value *PtrShadow = DFSF.getShadow(LI.getPointerOperand()); 1040 Shadow = DFSF.DFS.combineShadows(Shadow, PtrShadow, &LI); 1041 } 1042 if (Shadow != DFSF.DFS.ZeroShadow) 1043 DFSF.NonZeroChecks.insert(Shadow); 1044 1045 DFSF.setShadow(&LI, Shadow); 1046} 1047 1048void DFSanFunction::storeShadow(Value *Addr, uint64_t Size, uint64_t Align, 1049 Value *Shadow, Instruction *Pos) { 1050 if (AllocaInst *AI = dyn_cast<AllocaInst>(Addr)) { 1051 llvm::DenseMap<AllocaInst *, AllocaInst *>::iterator i = 1052 AllocaShadowMap.find(AI); 1053 if (i != AllocaShadowMap.end()) { 1054 IRBuilder<> IRB(Pos); 1055 IRB.CreateStore(Shadow, i->second); 1056 return; 1057 } 1058 } 1059 1060 uint64_t ShadowAlign = Align * DFS.ShadowWidth / 8; 1061 IRBuilder<> IRB(Pos); 1062 Value *ShadowAddr = DFS.getShadowAddress(Addr, Pos); 1063 if (Shadow == DFS.ZeroShadow) { 1064 IntegerType *ShadowTy = IntegerType::get(*DFS.Ctx, Size * DFS.ShadowWidth); 1065 Value *ExtZeroShadow = ConstantInt::get(ShadowTy, 0); 1066 Value *ExtShadowAddr = 1067 IRB.CreateBitCast(ShadowAddr, PointerType::getUnqual(ShadowTy)); 1068 IRB.CreateAlignedStore(ExtZeroShadow, ExtShadowAddr, ShadowAlign); 1069 return; 1070 } 1071 1072 const unsigned ShadowVecSize = 128 / DFS.ShadowWidth; 1073 uint64_t Offset = 0; 1074 if (Size >= ShadowVecSize) { 1075 VectorType *ShadowVecTy = VectorType::get(DFS.ShadowTy, ShadowVecSize); 1076 Value *ShadowVec = UndefValue::get(ShadowVecTy); 1077 for (unsigned i = 0; i != ShadowVecSize; ++i) { 1078 ShadowVec = IRB.CreateInsertElement( 1079 ShadowVec, Shadow, ConstantInt::get(Type::getInt32Ty(*DFS.Ctx), i)); 1080 } 1081 Value *ShadowVecAddr = 1082 IRB.CreateBitCast(ShadowAddr, PointerType::getUnqual(ShadowVecTy)); 1083 do { 1084 Value *CurShadowVecAddr = IRB.CreateConstGEP1_32(ShadowVecAddr, Offset); 1085 IRB.CreateAlignedStore(ShadowVec, CurShadowVecAddr, ShadowAlign); 1086 Size -= ShadowVecSize; 1087 ++Offset; 1088 } while (Size >= ShadowVecSize); 1089 Offset *= ShadowVecSize; 1090 } 1091 while (Size > 0) { 1092 Value *CurShadowAddr = IRB.CreateConstGEP1_32(ShadowAddr, Offset); 1093 IRB.CreateAlignedStore(Shadow, CurShadowAddr, ShadowAlign); 1094 --Size; 1095 ++Offset; 1096 } 1097} 1098 1099void DFSanVisitor::visitStoreInst(StoreInst &SI) { 1100 uint64_t Size = 1101 DFSF.DFS.DL->getTypeStoreSize(SI.getValueOperand()->getType()); 1102 uint64_t Align; 1103 if (ClPreserveAlignment) { 1104 Align = SI.getAlignment(); 1105 if (Align == 0) 1106 Align = DFSF.DFS.DL->getABITypeAlignment(SI.getValueOperand()->getType()); 1107 } else { 1108 Align = 1; 1109 } 1110 1111 Value* Shadow = DFSF.getShadow(SI.getValueOperand()); 1112 if (ClCombinePointerLabelsOnStore) { 1113 Value *PtrShadow = DFSF.getShadow(SI.getPointerOperand()); 1114 Shadow = DFSF.DFS.combineShadows(Shadow, PtrShadow, &SI); 1115 } 1116 DFSF.storeShadow(SI.getPointerOperand(), Size, Align, Shadow, &SI); 1117} 1118 1119void DFSanVisitor::visitBinaryOperator(BinaryOperator &BO) { 1120 visitOperandShadowInst(BO); 1121} 1122 1123void DFSanVisitor::visitCastInst(CastInst &CI) { visitOperandShadowInst(CI); } 1124 1125void DFSanVisitor::visitCmpInst(CmpInst &CI) { visitOperandShadowInst(CI); } 1126 1127void DFSanVisitor::visitGetElementPtrInst(GetElementPtrInst &GEPI) { 1128 visitOperandShadowInst(GEPI); 1129} 1130 1131void DFSanVisitor::visitExtractElementInst(ExtractElementInst &I) { 1132 visitOperandShadowInst(I); 1133} 1134 1135void DFSanVisitor::visitInsertElementInst(InsertElementInst &I) { 1136 visitOperandShadowInst(I); 1137} 1138 1139void DFSanVisitor::visitShuffleVectorInst(ShuffleVectorInst &I) { 1140 visitOperandShadowInst(I); 1141} 1142 1143void DFSanVisitor::visitExtractValueInst(ExtractValueInst &I) { 1144 visitOperandShadowInst(I); 1145} 1146 1147void DFSanVisitor::visitInsertValueInst(InsertValueInst &I) { 1148 visitOperandShadowInst(I); 1149} 1150 1151void DFSanVisitor::visitAllocaInst(AllocaInst &I) { 1152 bool AllLoadsStores = true; 1153 for (User *U : I.users()) { 1154 if (isa<LoadInst>(U)) 1155 continue; 1156 1157 if (StoreInst *SI = dyn_cast<StoreInst>(U)) { 1158 if (SI->getPointerOperand() == &I) 1159 continue; 1160 } 1161 1162 AllLoadsStores = false; 1163 break; 1164 } 1165 if (AllLoadsStores) { 1166 IRBuilder<> IRB(&I); 1167 DFSF.AllocaShadowMap[&I] = IRB.CreateAlloca(DFSF.DFS.ShadowTy); 1168 } 1169 DFSF.setShadow(&I, DFSF.DFS.ZeroShadow); 1170} 1171 1172void DFSanVisitor::visitSelectInst(SelectInst &I) { 1173 Value *CondShadow = DFSF.getShadow(I.getCondition()); 1174 Value *TrueShadow = DFSF.getShadow(I.getTrueValue()); 1175 Value *FalseShadow = DFSF.getShadow(I.getFalseValue()); 1176 1177 if (isa<VectorType>(I.getCondition()->getType())) { 1178 DFSF.setShadow( 1179 &I, DFSF.DFS.combineShadows( 1180 CondShadow, 1181 DFSF.DFS.combineShadows(TrueShadow, FalseShadow, &I), &I)); 1182 } else { 1183 Value *ShadowSel; 1184 if (TrueShadow == FalseShadow) { 1185 ShadowSel = TrueShadow; 1186 } else { 1187 ShadowSel = 1188 SelectInst::Create(I.getCondition(), TrueShadow, FalseShadow, "", &I); 1189 } 1190 DFSF.setShadow(&I, DFSF.DFS.combineShadows(CondShadow, ShadowSel, &I)); 1191 } 1192} 1193 1194void DFSanVisitor::visitMemSetInst(MemSetInst &I) { 1195 IRBuilder<> IRB(&I); 1196 Value *ValShadow = DFSF.getShadow(I.getValue()); 1197 IRB.CreateCall3( 1198 DFSF.DFS.DFSanSetLabelFn, ValShadow, 1199 IRB.CreateBitCast(I.getDest(), Type::getInt8PtrTy(*DFSF.DFS.Ctx)), 1200 IRB.CreateZExtOrTrunc(I.getLength(), DFSF.DFS.IntptrTy)); 1201} 1202 1203void DFSanVisitor::visitMemTransferInst(MemTransferInst &I) { 1204 IRBuilder<> IRB(&I); 1205 Value *DestShadow = DFSF.DFS.getShadowAddress(I.getDest(), &I); 1206 Value *SrcShadow = DFSF.DFS.getShadowAddress(I.getSource(), &I); 1207 Value *LenShadow = IRB.CreateMul( 1208 I.getLength(), 1209 ConstantInt::get(I.getLength()->getType(), DFSF.DFS.ShadowWidth / 8)); 1210 Value *AlignShadow; 1211 if (ClPreserveAlignment) { 1212 AlignShadow = IRB.CreateMul(I.getAlignmentCst(), 1213 ConstantInt::get(I.getAlignmentCst()->getType(), 1214 DFSF.DFS.ShadowWidth / 8)); 1215 } else { 1216 AlignShadow = ConstantInt::get(I.getAlignmentCst()->getType(), 1217 DFSF.DFS.ShadowWidth / 8); 1218 } 1219 Type *Int8Ptr = Type::getInt8PtrTy(*DFSF.DFS.Ctx); 1220 DestShadow = IRB.CreateBitCast(DestShadow, Int8Ptr); 1221 SrcShadow = IRB.CreateBitCast(SrcShadow, Int8Ptr); 1222 IRB.CreateCall5(I.getCalledValue(), DestShadow, SrcShadow, LenShadow, 1223 AlignShadow, I.getVolatileCst()); 1224} 1225 1226void DFSanVisitor::visitReturnInst(ReturnInst &RI) { 1227 if (!DFSF.IsNativeABI && RI.getReturnValue()) { 1228 switch (DFSF.IA) { 1229 case DataFlowSanitizer::IA_TLS: { 1230 Value *S = DFSF.getShadow(RI.getReturnValue()); 1231 IRBuilder<> IRB(&RI); 1232 IRB.CreateStore(S, DFSF.getRetvalTLS()); 1233 break; 1234 } 1235 case DataFlowSanitizer::IA_Args: { 1236 IRBuilder<> IRB(&RI); 1237 Type *RT = DFSF.F->getFunctionType()->getReturnType(); 1238 Value *InsVal = 1239 IRB.CreateInsertValue(UndefValue::get(RT), RI.getReturnValue(), 0); 1240 Value *InsShadow = 1241 IRB.CreateInsertValue(InsVal, DFSF.getShadow(RI.getReturnValue()), 1); 1242 RI.setOperand(0, InsShadow); 1243 break; 1244 } 1245 } 1246 } 1247} 1248 1249void DFSanVisitor::visitCallSite(CallSite CS) { 1250 Function *F = CS.getCalledFunction(); 1251 if ((F && F->isIntrinsic()) || isa<InlineAsm>(CS.getCalledValue())) { 1252 visitOperandShadowInst(*CS.getInstruction()); 1253 return; 1254 } 1255 1256 IRBuilder<> IRB(CS.getInstruction()); 1257 1258 DenseMap<Value *, Function *>::iterator i = 1259 DFSF.DFS.UnwrappedFnMap.find(CS.getCalledValue()); 1260 if (i != DFSF.DFS.UnwrappedFnMap.end()) { 1261 Function *F = i->second; 1262 switch (DFSF.DFS.getWrapperKind(F)) { 1263 case DataFlowSanitizer::WK_Warning: { 1264 CS.setCalledFunction(F); 1265 IRB.CreateCall(DFSF.DFS.DFSanUnimplementedFn, 1266 IRB.CreateGlobalStringPtr(F->getName())); 1267 DFSF.setShadow(CS.getInstruction(), DFSF.DFS.ZeroShadow); 1268 return; 1269 } 1270 case DataFlowSanitizer::WK_Discard: { 1271 CS.setCalledFunction(F); 1272 DFSF.setShadow(CS.getInstruction(), DFSF.DFS.ZeroShadow); 1273 return; 1274 } 1275 case DataFlowSanitizer::WK_Functional: { 1276 CS.setCalledFunction(F); 1277 visitOperandShadowInst(*CS.getInstruction()); 1278 return; 1279 } 1280 case DataFlowSanitizer::WK_Custom: { 1281 // Don't try to handle invokes of custom functions, it's too complicated. 1282 // Instead, invoke the dfsw$ wrapper, which will in turn call the __dfsw_ 1283 // wrapper. 1284 if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction())) { 1285 FunctionType *FT = F->getFunctionType(); 1286 FunctionType *CustomFT = DFSF.DFS.getCustomFunctionType(FT); 1287 std::string CustomFName = "__dfsw_"; 1288 CustomFName += F->getName(); 1289 Constant *CustomF = 1290 DFSF.DFS.Mod->getOrInsertFunction(CustomFName, CustomFT); 1291 if (Function *CustomFn = dyn_cast<Function>(CustomF)) { 1292 CustomFn->copyAttributesFrom(F); 1293 1294 // Custom functions returning non-void will write to the return label. 1295 if (!FT->getReturnType()->isVoidTy()) { 1296 CustomFn->removeAttributes(AttributeSet::FunctionIndex, 1297 DFSF.DFS.ReadOnlyNoneAttrs); 1298 } 1299 } 1300 1301 std::vector<Value *> Args; 1302 1303 CallSite::arg_iterator i = CS.arg_begin(); 1304 for (unsigned n = FT->getNumParams(); n != 0; ++i, --n) { 1305 Type *T = (*i)->getType(); 1306 FunctionType *ParamFT; 1307 if (isa<PointerType>(T) && 1308 (ParamFT = dyn_cast<FunctionType>( 1309 cast<PointerType>(T)->getElementType()))) { 1310 std::string TName = "dfst"; 1311 TName += utostr(FT->getNumParams() - n); 1312 TName += "$"; 1313 TName += F->getName(); 1314 Constant *T = DFSF.DFS.getOrBuildTrampolineFunction(ParamFT, TName); 1315 Args.push_back(T); 1316 Args.push_back( 1317 IRB.CreateBitCast(*i, Type::getInt8PtrTy(*DFSF.DFS.Ctx))); 1318 } else { 1319 Args.push_back(*i); 1320 } 1321 } 1322 1323 i = CS.arg_begin(); 1324 for (unsigned n = FT->getNumParams(); n != 0; ++i, --n) 1325 Args.push_back(DFSF.getShadow(*i)); 1326 1327 if (!FT->getReturnType()->isVoidTy()) { 1328 if (!DFSF.LabelReturnAlloca) { 1329 DFSF.LabelReturnAlloca = 1330 new AllocaInst(DFSF.DFS.ShadowTy, "labelreturn", 1331 DFSF.F->getEntryBlock().begin()); 1332 } 1333 Args.push_back(DFSF.LabelReturnAlloca); 1334 } 1335 1336 CallInst *CustomCI = IRB.CreateCall(CustomF, Args); 1337 CustomCI->setCallingConv(CI->getCallingConv()); 1338 CustomCI->setAttributes(CI->getAttributes()); 1339 1340 if (!FT->getReturnType()->isVoidTy()) { 1341 LoadInst *LabelLoad = IRB.CreateLoad(DFSF.LabelReturnAlloca); 1342 DFSF.setShadow(CustomCI, LabelLoad); 1343 } 1344 1345 CI->replaceAllUsesWith(CustomCI); 1346 CI->eraseFromParent(); 1347 return; 1348 } 1349 break; 1350 } 1351 } 1352 } 1353 1354 FunctionType *FT = cast<FunctionType>( 1355 CS.getCalledValue()->getType()->getPointerElementType()); 1356 if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_TLS) { 1357 for (unsigned i = 0, n = FT->getNumParams(); i != n; ++i) { 1358 IRB.CreateStore(DFSF.getShadow(CS.getArgument(i)), 1359 DFSF.getArgTLS(i, CS.getInstruction())); 1360 } 1361 } 1362 1363 Instruction *Next = nullptr; 1364 if (!CS.getType()->isVoidTy()) { 1365 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) { 1366 if (II->getNormalDest()->getSinglePredecessor()) { 1367 Next = II->getNormalDest()->begin(); 1368 } else { 1369 BasicBlock *NewBB = 1370 SplitEdge(II->getParent(), II->getNormalDest(), &DFSF.DFS); 1371 Next = NewBB->begin(); 1372 } 1373 } else { 1374 Next = CS->getNextNode(); 1375 } 1376 1377 if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_TLS) { 1378 IRBuilder<> NextIRB(Next); 1379 LoadInst *LI = NextIRB.CreateLoad(DFSF.getRetvalTLS()); 1380 DFSF.SkipInsts.insert(LI); 1381 DFSF.setShadow(CS.getInstruction(), LI); 1382 DFSF.NonZeroChecks.insert(LI); 1383 } 1384 } 1385 1386 // Do all instrumentation for IA_Args down here to defer tampering with the 1387 // CFG in a way that SplitEdge may be able to detect. 1388 if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_Args) { 1389 FunctionType *NewFT = DFSF.DFS.getArgsFunctionType(FT); 1390 Value *Func = 1391 IRB.CreateBitCast(CS.getCalledValue(), PointerType::getUnqual(NewFT)); 1392 std::vector<Value *> Args; 1393 1394 CallSite::arg_iterator i = CS.arg_begin(), e = CS.arg_end(); 1395 for (unsigned n = FT->getNumParams(); n != 0; ++i, --n) 1396 Args.push_back(*i); 1397 1398 i = CS.arg_begin(); 1399 for (unsigned n = FT->getNumParams(); n != 0; ++i, --n) 1400 Args.push_back(DFSF.getShadow(*i)); 1401 1402 if (FT->isVarArg()) { 1403 unsigned VarArgSize = CS.arg_size() - FT->getNumParams(); 1404 ArrayType *VarArgArrayTy = ArrayType::get(DFSF.DFS.ShadowTy, VarArgSize); 1405 AllocaInst *VarArgShadow = 1406 new AllocaInst(VarArgArrayTy, "", DFSF.F->getEntryBlock().begin()); 1407 Args.push_back(IRB.CreateConstGEP2_32(VarArgShadow, 0, 0)); 1408 for (unsigned n = 0; i != e; ++i, ++n) { 1409 IRB.CreateStore(DFSF.getShadow(*i), 1410 IRB.CreateConstGEP2_32(VarArgShadow, 0, n)); 1411 Args.push_back(*i); 1412 } 1413 } 1414 1415 CallSite NewCS; 1416 if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) { 1417 NewCS = IRB.CreateInvoke(Func, II->getNormalDest(), II->getUnwindDest(), 1418 Args); 1419 } else { 1420 NewCS = IRB.CreateCall(Func, Args); 1421 } 1422 NewCS.setCallingConv(CS.getCallingConv()); 1423 NewCS.setAttributes(CS.getAttributes().removeAttributes( 1424 *DFSF.DFS.Ctx, AttributeSet::ReturnIndex, 1425 AttributeFuncs::typeIncompatible(NewCS.getInstruction()->getType(), 1426 AttributeSet::ReturnIndex))); 1427 1428 if (Next) { 1429 ExtractValueInst *ExVal = 1430 ExtractValueInst::Create(NewCS.getInstruction(), 0, "", Next); 1431 DFSF.SkipInsts.insert(ExVal); 1432 ExtractValueInst *ExShadow = 1433 ExtractValueInst::Create(NewCS.getInstruction(), 1, "", Next); 1434 DFSF.SkipInsts.insert(ExShadow); 1435 DFSF.setShadow(ExVal, ExShadow); 1436 DFSF.NonZeroChecks.insert(ExShadow); 1437 1438 CS.getInstruction()->replaceAllUsesWith(ExVal); 1439 } 1440 1441 CS.getInstruction()->eraseFromParent(); 1442 } 1443} 1444 1445void DFSanVisitor::visitPHINode(PHINode &PN) { 1446 PHINode *ShadowPN = 1447 PHINode::Create(DFSF.DFS.ShadowTy, PN.getNumIncomingValues(), "", &PN); 1448 1449 // Give the shadow phi node valid predecessors to fool SplitEdge into working. 1450 Value *UndefShadow = UndefValue::get(DFSF.DFS.ShadowTy); 1451 for (PHINode::block_iterator i = PN.block_begin(), e = PN.block_end(); i != e; 1452 ++i) { 1453 ShadowPN->addIncoming(UndefShadow, *i); 1454 } 1455 1456 DFSF.PHIFixups.push_back(std::make_pair(&PN, ShadowPN)); 1457 DFSF.setShadow(&PN, ShadowPN); 1458} 1459