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
18 using namespace clang;
19 using namespace CodeGen;
20
SanitizerMetadata(CodeGenModule & CGM)21 SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {}
22
isAsanHwasanOrMemTag(const SanitizerSet & SS)23 static bool isAsanHwasanOrMemTag(const SanitizerSet& SS) {
24 return SS.hasOneOf(SanitizerKind::Address | SanitizerKind::KernelAddress |
25 SanitizerKind::HWAddress | SanitizerKind::KernelHWAddress |
26 SanitizerKind::MemTag);
27 }
28
reportGlobalToASan(llvm::GlobalVariable * GV,SourceLocation Loc,StringRef Name,QualType Ty,bool IsDynInit,bool IsBlacklisted)29 void 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
reportGlobalToASan(llvm::GlobalVariable * GV,const VarDecl & D,bool IsDynInit)62 void 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
disableSanitizerForGlobal(llvm::GlobalVariable * GV)78 void 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
disableSanitizerForInstruction(llvm::Instruction * I)85 void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
86 I->setMetadata(CGM.getModule().getMDKindID("nosanitize"),
87 llvm::MDNode::get(CGM.getLLVMContext(), None));
88 }
89
getLocationMetadata(SourceLocation Loc)90 llvm::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