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 17 using namespace clang; 18 using namespace CodeGen; 19 20 SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {} 21 22 static bool isAsanHwasanMemTagOrTysan(const SanitizerSet &SS) { 23 return SS.hasOneOf(SanitizerKind::Address | SanitizerKind::KernelAddress | 24 SanitizerKind::HWAddress | SanitizerKind::MemTag | 25 SanitizerKind::Type); 26 } 27 28 static SanitizerMask expandKernelSanitizerMasks(SanitizerMask Mask) { 29 if (Mask & (SanitizerKind::Address | SanitizerKind::KernelAddress)) 30 Mask |= SanitizerKind::Address | SanitizerKind::KernelAddress; 31 // Note: KHWASan doesn't support globals. 32 return Mask; 33 } 34 35 void SanitizerMetadata::reportGlobal(llvm::GlobalVariable *GV, 36 SourceLocation Loc, StringRef Name, 37 QualType Ty, 38 SanitizerMask NoSanitizeAttrMask, 39 bool IsDynInit) { 40 SanitizerSet FsanitizeArgument = CGM.getLangOpts().Sanitize; 41 if (!isAsanHwasanMemTagOrTysan(FsanitizeArgument)) 42 return; 43 44 FsanitizeArgument.Mask = expandKernelSanitizerMasks(FsanitizeArgument.Mask); 45 NoSanitizeAttrMask = expandKernelSanitizerMasks(NoSanitizeAttrMask); 46 SanitizerSet NoSanitizeAttrSet = {NoSanitizeAttrMask & 47 FsanitizeArgument.Mask}; 48 49 llvm::GlobalVariable::SanitizerMetadata Meta; 50 if (GV->hasSanitizerMetadata()) 51 Meta = GV->getSanitizerMetadata(); 52 53 Meta.NoAddress |= NoSanitizeAttrSet.hasOneOf(SanitizerKind::Address); 54 Meta.NoAddress |= CGM.isInNoSanitizeList( 55 FsanitizeArgument.Mask & SanitizerKind::Address, GV, Loc, Ty); 56 57 Meta.NoHWAddress |= NoSanitizeAttrSet.hasOneOf(SanitizerKind::HWAddress); 58 Meta.NoHWAddress |= CGM.isInNoSanitizeList( 59 FsanitizeArgument.Mask & SanitizerKind::HWAddress, GV, Loc, Ty); 60 61 Meta.Memtag |= 62 static_cast<bool>(FsanitizeArgument.Mask & SanitizerKind::MemtagGlobals); 63 Meta.Memtag &= !NoSanitizeAttrSet.hasOneOf(SanitizerKind::MemTag); 64 Meta.Memtag &= !CGM.isInNoSanitizeList( 65 FsanitizeArgument.Mask & SanitizerKind::MemTag, GV, Loc, Ty); 66 67 Meta.IsDynInit = IsDynInit && !Meta.NoAddress && 68 FsanitizeArgument.has(SanitizerKind::Address) && 69 !CGM.isInNoSanitizeList(SanitizerKind::Address | 70 SanitizerKind::KernelAddress, 71 GV, Loc, Ty, "init"); 72 73 GV->setSanitizerMetadata(Meta); 74 75 if (Ty.isNull() || !CGM.getLangOpts().Sanitize.has(SanitizerKind::Type) || 76 NoSanitizeAttrMask & SanitizerKind::Type) 77 return; 78 79 llvm::MDNode *TBAAInfo = CGM.getTBAATypeInfo(Ty); 80 if (!TBAAInfo || TBAAInfo == CGM.getTBAATypeInfo(CGM.getContext().CharTy)) 81 return; 82 83 llvm::Metadata *GlobalMetadata[] = {llvm::ConstantAsMetadata::get(GV), 84 TBAAInfo}; 85 86 // Metadata for the global already registered. 87 if (llvm::MDNode::getIfExists(CGM.getLLVMContext(), GlobalMetadata)) 88 return; 89 90 llvm::MDNode *ThisGlobal = 91 llvm::MDNode::get(CGM.getLLVMContext(), GlobalMetadata); 92 llvm::NamedMDNode *TysanGlobals = 93 CGM.getModule().getOrInsertNamedMetadata("llvm.tysan.globals"); 94 TysanGlobals->addOperand(ThisGlobal); 95 } 96 97 void SanitizerMetadata::reportGlobal(llvm::GlobalVariable *GV, const VarDecl &D, 98 bool IsDynInit) { 99 if (!isAsanHwasanMemTagOrTysan(CGM.getLangOpts().Sanitize)) 100 return; 101 std::string QualName; 102 llvm::raw_string_ostream OS(QualName); 103 D.printQualifiedName(OS); 104 105 auto getNoSanitizeMask = [](const VarDecl &D) { 106 if (D.hasAttr<DisableSanitizerInstrumentationAttr>()) 107 return SanitizerKind::All; 108 109 SanitizerMask NoSanitizeMask; 110 for (auto *Attr : D.specific_attrs<NoSanitizeAttr>()) 111 NoSanitizeMask |= Attr->getMask(); 112 113 // External definitions and incomplete types get handled at the place they 114 // are defined. 115 if (D.hasExternalStorage() || D.getType()->isIncompleteType()) 116 NoSanitizeMask |= SanitizerKind::Type; 117 118 return NoSanitizeMask; 119 }; 120 121 reportGlobal(GV, D.getLocation(), QualName, D.getType(), getNoSanitizeMask(D), 122 IsDynInit); 123 } 124 125 void SanitizerMetadata::disableSanitizerForGlobal(llvm::GlobalVariable *GV) { 126 reportGlobal(GV, SourceLocation(), "", QualType(), SanitizerKind::All); 127 } 128