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::MemTag);
28 }
29 
30 SanitizerMask expandKernelSanitizerMasks(SanitizerMask Mask) {
31   if (Mask & (SanitizerKind::Address | SanitizerKind::KernelAddress))
32     Mask |= SanitizerKind::Address | SanitizerKind::KernelAddress;
33   // Note: KHWASan doesn't support globals.
34   return Mask;
35 }
36 
37 void SanitizerMetadata::reportGlobal(llvm::GlobalVariable *GV,
38                                      SourceLocation Loc, StringRef Name,
39                                      QualType Ty,
40                                      SanitizerMask NoSanitizeAttrMask,
41                                      bool IsDynInit) {
42   SanitizerSet FsanitizeArgument = CGM.getLangOpts().Sanitize;
43   if (!isAsanHwasanOrMemTag(FsanitizeArgument))
44     return;
45 
46   FsanitizeArgument.Mask = expandKernelSanitizerMasks(FsanitizeArgument.Mask);
47   NoSanitizeAttrMask = expandKernelSanitizerMasks(NoSanitizeAttrMask);
48   SanitizerSet NoSanitizeAttrSet = {NoSanitizeAttrMask &
49                                     FsanitizeArgument.Mask};
50 
51   llvm::GlobalVariable::SanitizerMetadata Meta;
52   if (GV->hasSanitizerMetadata())
53     Meta = GV->getSanitizerMetadata();
54 
55   Meta.NoAddress |= NoSanitizeAttrSet.hasOneOf(SanitizerKind::Address);
56   Meta.NoAddress |= CGM.isInNoSanitizeList(
57       FsanitizeArgument.Mask & SanitizerKind::Address, GV, Loc, Ty);
58 
59   Meta.NoHWAddress |= NoSanitizeAttrSet.hasOneOf(SanitizerKind::HWAddress);
60   Meta.NoHWAddress |= CGM.isInNoSanitizeList(
61       FsanitizeArgument.Mask & SanitizerKind::HWAddress, GV, Loc, Ty);
62 
63   Meta.Memtag |=
64       static_cast<bool>(FsanitizeArgument.Mask & SanitizerKind::MemtagGlobals);
65   Meta.Memtag &= !NoSanitizeAttrSet.hasOneOf(SanitizerKind::MemTag);
66   Meta.Memtag &= !CGM.isInNoSanitizeList(
67       FsanitizeArgument.Mask & SanitizerKind::MemTag, GV, Loc, Ty);
68 
69   Meta.IsDynInit = IsDynInit && !Meta.NoAddress &&
70                    FsanitizeArgument.has(SanitizerKind::Address) &&
71                    !CGM.isInNoSanitizeList(SanitizerKind::Address |
72                                                SanitizerKind::KernelAddress,
73                                            GV, Loc, Ty, "init");
74 
75   GV->setSanitizerMetadata(Meta);
76 }
77 
78 void SanitizerMetadata::reportGlobal(llvm::GlobalVariable *GV, const VarDecl &D,
79                                      bool IsDynInit) {
80   if (!isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize))
81     return;
82   std::string QualName;
83   llvm::raw_string_ostream OS(QualName);
84   D.printQualifiedName(OS);
85 
86   auto getNoSanitizeMask = [](const VarDecl &D) {
87     if (D.hasAttr<DisableSanitizerInstrumentationAttr>())
88       return SanitizerKind::All;
89 
90     SanitizerMask NoSanitizeMask;
91     for (auto *Attr : D.specific_attrs<NoSanitizeAttr>())
92       NoSanitizeMask |= Attr->getMask();
93 
94     return NoSanitizeMask;
95   };
96 
97   reportGlobal(GV, D.getLocation(), OS.str(), D.getType(), getNoSanitizeMask(D),
98                IsDynInit);
99 }
100 
101 void SanitizerMetadata::disableSanitizerForGlobal(llvm::GlobalVariable *GV) {
102   reportGlobal(GV, SourceLocation(), "", QualType(), SanitizerKind::All);
103 }
104 
105 void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
106   I->setMetadata(llvm::LLVMContext::MD_nosanitize,
107                  llvm::MDNode::get(CGM.getLLVMContext(), std::nullopt));
108 }
109