1 //===--- SanitizerMetadata.cpp - Blacklist for sanitizers -----------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Class which emits metadata consumed by sanitizer instrumentation passes.
11 //
12 //===----------------------------------------------------------------------===//
13 #include "SanitizerMetadata.h"
14 #include "CodeGenModule.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 
22 SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {}
23 
24 void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
25                                            SourceLocation Loc, StringRef Name,
26                                            QualType Ty, bool IsDynInit,
27                                            bool IsBlacklisted) {
28   if (!CGM.getLangOpts().Sanitize.hasOneOf(SanitizerKind::Address |
29                                            SanitizerKind::KernelAddress |
30                                            SanitizerKind::HWAddress))
31     return;
32   IsDynInit &= !CGM.isInSanitizerBlacklist(GV, Loc, Ty, "init");
33   IsBlacklisted |= CGM.isInSanitizerBlacklist(GV, Loc, Ty);
34 
35   llvm::Metadata *LocDescr = nullptr;
36   llvm::Metadata *GlobalName = nullptr;
37   llvm::LLVMContext &VMContext = CGM.getLLVMContext();
38   if (!IsBlacklisted) {
39     // Don't generate source location and global name if it is blacklisted -
40     // it won't be instrumented anyway.
41     LocDescr = getLocationMetadata(Loc);
42     if (!Name.empty())
43       GlobalName = llvm::MDString::get(VMContext, Name);
44   }
45 
46   llvm::Metadata *GlobalMetadata[] = {
47       llvm::ConstantAsMetadata::get(GV), LocDescr, GlobalName,
48       llvm::ConstantAsMetadata::get(
49           llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), IsDynInit)),
50       llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
51           llvm::Type::getInt1Ty(VMContext), IsBlacklisted))};
52 
53   llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalMetadata);
54   llvm::NamedMDNode *AsanGlobals =
55       CGM.getModule().getOrInsertNamedMetadata("llvm.asan.globals");
56   AsanGlobals->addOperand(ThisGlobal);
57 }
58 
59 void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
60                                            const VarDecl &D, bool IsDynInit) {
61   if (!CGM.getLangOpts().Sanitize.hasOneOf(SanitizerKind::Address |
62                                            SanitizerKind::KernelAddress |
63                                            SanitizerKind::HWAddress))
64     return;
65   std::string QualName;
66   llvm::raw_string_ostream OS(QualName);
67   D.printQualifiedName(OS);
68 
69   bool IsBlacklisted = false;
70   for (auto Attr : D.specific_attrs<NoSanitizeAttr>())
71     if (Attr->getMask() & SanitizerKind::Address)
72       IsBlacklisted = true;
73   reportGlobalToASan(GV, D.getLocation(), OS.str(), D.getType(), IsDynInit,
74                      IsBlacklisted);
75 }
76 
77 void SanitizerMetadata::disableSanitizerForGlobal(llvm::GlobalVariable *GV) {
78   // For now, just make sure the global is not modified by the ASan
79   // instrumentation.
80   if (CGM.getLangOpts().Sanitize.hasOneOf(SanitizerKind::Address |
81                                           SanitizerKind::KernelAddress |
82                                           SanitizerKind::HWAddress))
83     reportGlobalToASan(GV, SourceLocation(), "", QualType(), false, true);
84 }
85 
86 void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
87   I->setMetadata(CGM.getModule().getMDKindID("nosanitize"),
88                  llvm::MDNode::get(CGM.getLLVMContext(), None));
89 }
90 
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