1 //===--- SanitizerMetadata.cpp - Ignored entities for sanitizers ----------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Class which emits metadata consumed by sanitizer instrumentation passes. 10 // 11 //===----------------------------------------------------------------------===// 12 #include "SanitizerMetadata.h" 13 #include "CodeGenModule.h" 14 #include "clang/AST/Attr.h" 15 #include "clang/AST/Type.h" 16 #include "clang/Basic/SourceManager.h" 17 #include "llvm/ADT/StringRef.h" 18 #include "llvm/IR/Constants.h" 19 20 using namespace clang; 21 using namespace CodeGen; 22 23 SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {} 24 25 static bool isAsanHwasanOrMemTag(const SanitizerSet& SS) { 26 return SS.hasOneOf(SanitizerKind::Address | SanitizerKind::KernelAddress | 27 SanitizerKind::HWAddress | SanitizerKind::KernelHWAddress | 28 SanitizerKind::MemTag); 29 } 30 31 void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV, 32 SourceLocation Loc, StringRef Name, 33 QualType Ty, bool IsDynInit, 34 bool IsExcluded) { 35 if (!isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize)) 36 return; 37 IsDynInit &= !CGM.isInNoSanitizeList(GV, Loc, Ty, "init"); 38 IsExcluded |= CGM.isInNoSanitizeList(GV, Loc, Ty); 39 40 llvm::Metadata *LocDescr = nullptr; 41 llvm::Metadata *GlobalName = nullptr; 42 llvm::LLVMContext &VMContext = CGM.getLLVMContext(); 43 if (!IsExcluded) { 44 // Don't generate source location and global name if it is on 45 // the NoSanitizeList - it won't be instrumented anyway. 46 LocDescr = getLocationMetadata(Loc); 47 if (!Name.empty()) 48 GlobalName = llvm::MDString::get(VMContext, Name); 49 } 50 51 llvm::Metadata *GlobalMetadata[] = { 52 llvm::ConstantAsMetadata::get(GV), LocDescr, GlobalName, 53 llvm::ConstantAsMetadata::get( 54 llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), IsDynInit)), 55 llvm::ConstantAsMetadata::get(llvm::ConstantInt::get( 56 llvm::Type::getInt1Ty(VMContext), IsExcluded))}; 57 58 llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalMetadata); 59 llvm::NamedMDNode *AsanGlobals = 60 CGM.getModule().getOrInsertNamedMetadata("llvm.asan.globals"); 61 AsanGlobals->addOperand(ThisGlobal); 62 } 63 64 void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV, 65 const VarDecl &D, bool IsDynInit) { 66 if (!isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize)) 67 return; 68 std::string QualName; 69 llvm::raw_string_ostream OS(QualName); 70 D.printQualifiedName(OS); 71 72 bool IsExcluded = false; 73 for (auto Attr : D.specific_attrs<NoSanitizeAttr>()) 74 if (Attr->getMask() & SanitizerKind::Address) 75 IsExcluded = true; 76 reportGlobalToASan(GV, D.getLocation(), OS.str(), D.getType(), IsDynInit, 77 IsExcluded); 78 } 79 80 void SanitizerMetadata::disableSanitizerForGlobal(llvm::GlobalVariable *GV) { 81 // For now, just make sure the global is not modified by the ASan 82 // instrumentation. 83 if (isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize)) 84 reportGlobalToASan(GV, SourceLocation(), "", QualType(), false, true); 85 } 86 87 void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) { 88 I->setMetadata(CGM.getModule().getMDKindID("nosanitize"), 89 llvm::MDNode::get(CGM.getLLVMContext(), None)); 90 } 91 92 llvm::MDNode *SanitizerMetadata::getLocationMetadata(SourceLocation Loc) { 93 PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc); 94 if (!PLoc.isValid()) 95 return nullptr; 96 llvm::LLVMContext &VMContext = CGM.getLLVMContext(); 97 llvm::Metadata *LocMetadata[] = { 98 llvm::MDString::get(VMContext, PLoc.getFilename()), 99 llvm::ConstantAsMetadata::get(llvm::ConstantInt::get( 100 llvm::Type::getInt32Ty(VMContext), PLoc.getLine())), 101 llvm::ConstantAsMetadata::get(llvm::ConstantInt::get( 102 llvm::Type::getInt32Ty(VMContext), PLoc.getColumn())), 103 }; 104 return llvm::MDNode::get(VMContext, LocMetadata); 105 } 106