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