SanitizerMetadata.cpp revision 1.1.1.1 
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
18using namespace clang;
19using namespace CodeGen;
20
21SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {}
22
23static bool isAsanHwasanOrMemTag(const SanitizerSet& SS) {
24  return SS.hasOneOf(SanitizerKind::Address | SanitizerKind::KernelAddress |
25                     SanitizerKind::HWAddress | SanitizerKind::KernelHWAddress |
26                     SanitizerKind::MemTag);
27}
28
29void 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
62void 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
78void 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
85void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
86  I->setMetadata(CGM.getModule().getMDKindID("nosanitize"),
87                 llvm::MDNode::get(CGM.getLLVMContext(), None));
88}
89
90llvm::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