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
19 using namespace clang;
20 using namespace CodeGen;
21
SanitizerMetadata(CodeGenModule & CGM)22 SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {}
23
isAsanHwasanOrMemTag(const SanitizerSet & SS)24 static bool isAsanHwasanOrMemTag(const SanitizerSet& SS) {
25 return SS.hasOneOf(SanitizerKind::Address | SanitizerKind::KernelAddress |
26 SanitizerKind::HWAddress | SanitizerKind::KernelHWAddress |
27 SanitizerKind::MemTag);
28 }
29
reportGlobalToASan(llvm::GlobalVariable * GV,SourceLocation Loc,StringRef Name,QualType Ty,bool IsDynInit,bool IsBlacklisted)30 void 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
reportGlobalToASan(llvm::GlobalVariable * GV,const VarDecl & D,bool IsDynInit)63 void 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
disableSanitizerForGlobal(llvm::GlobalVariable * GV)79 void 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
disableSanitizerForInstruction(llvm::Instruction * I)86 void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
87 I->setMetadata(CGM.getModule().getMDKindID("nosanitize"),
88 llvm::MDNode::get(CGM.getLLVMContext(), None));
89 }
90
getLocationMetadata(SourceLocation Loc)91 llvm::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