SanitizerMetadata.cpp revision 360784 
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
19using namespace clang;
20using namespace CodeGen;
21
22SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {}
23
24static bool isAsanHwasanOrMemTag(const SanitizerSet& SS) {
25  return SS.hasOneOf(SanitizerKind::Address | SanitizerKind::KernelAddress |
26                     SanitizerKind::HWAddress | SanitizerKind::KernelHWAddress |
27                     SanitizerKind::MemTag);
28}
29
30void 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
63void 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
79void 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
86void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
87  I->setMetadata(CGM.getModule().getMDKindID("nosanitize"),
88                 llvm::MDNode::get(CGM.getLLVMContext(), None));
89}
90
91llvm::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