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     return;
31   IsDynInit &= !CGM.isInSanitizerBlacklist(GV, Loc, Ty, "init");
32   IsBlacklisted |= CGM.isInSanitizerBlacklist(GV, Loc, Ty);
33 
34   llvm::Metadata *LocDescr = nullptr;
35   llvm::Metadata *GlobalName = nullptr;
36   llvm::LLVMContext &VMContext = CGM.getLLVMContext();
37   if (!IsBlacklisted) {
38     // Don't generate source location and global name if it is blacklisted -
39     // it won't be instrumented anyway.
40     LocDescr = getLocationMetadata(Loc);
41     if (!Name.empty())
42       GlobalName = llvm::MDString::get(VMContext, Name);
43   }
44 
45   llvm::Metadata *GlobalMetadata[] = {
46       llvm::ConstantAsMetadata::get(GV), LocDescr, GlobalName,
47       llvm::ConstantAsMetadata::get(
48           llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), IsDynInit)),
49       llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
50           llvm::Type::getInt1Ty(VMContext), IsBlacklisted))};
51 
52   llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalMetadata);
53   llvm::NamedMDNode *AsanGlobals =
54       CGM.getModule().getOrInsertNamedMetadata("llvm.asan.globals");
55   AsanGlobals->addOperand(ThisGlobal);
56 }
57 
58 void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
59                                            const VarDecl &D, bool IsDynInit) {
60   if (!CGM.getLangOpts().Sanitize.hasOneOf(SanitizerKind::Address |
61                                            SanitizerKind::KernelAddress))
62     return;
63   std::string QualName;
64   llvm::raw_string_ostream OS(QualName);
65   D.printQualifiedName(OS);
66 
67   bool IsBlacklisted = false;
68   for (auto Attr : D.specific_attrs<NoSanitizeAttr>())
69     if (Attr->getMask() & SanitizerKind::Address)
70       IsBlacklisted = true;
71   reportGlobalToASan(GV, D.getLocation(), OS.str(), D.getType(), IsDynInit,
72                      IsBlacklisted);
73 }
74 
75 void SanitizerMetadata::disableSanitizerForGlobal(llvm::GlobalVariable *GV) {
76   // For now, just make sure the global is not modified by the ASan
77   // instrumentation.
78   if (CGM.getLangOpts().Sanitize.hasOneOf(SanitizerKind::Address |
79                                           SanitizerKind::KernelAddress))
80     reportGlobalToASan(GV, SourceLocation(), "", QualType(), false, true);
81 }
82 
83 void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
84   I->setMetadata(CGM.getModule().getMDKindID("nosanitize"),
85                  llvm::MDNode::get(CGM.getLLVMContext(), None));
86 }
87 
88 llvm::MDNode *SanitizerMetadata::getLocationMetadata(SourceLocation Loc) {
89   PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc);
90   if (!PLoc.isValid())
91     return nullptr;
92   llvm::LLVMContext &VMContext = CGM.getLLVMContext();
93   llvm::Metadata *LocMetadata[] = {
94       llvm::MDString::get(VMContext, PLoc.getFilename()),
95       llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
96           llvm::Type::getInt32Ty(VMContext), PLoc.getLine())),
97       llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
98           llvm::Type::getInt32Ty(VMContext), PLoc.getColumn())),
99   };
100   return llvm::MDNode::get(VMContext, LocMetadata);
101 }
102