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