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 
SanitizerMetadata(CodeGenModule & CGM)22 SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {}
23 
reportGlobalToASan(llvm::GlobalVariable * GV,SourceLocation Loc,StringRef Name,QualType Ty,bool IsDynInit,bool IsBlacklisted)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 
reportGlobalToASan(llvm::GlobalVariable * GV,const VarDecl & D,bool IsDynInit)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   reportGlobalToASan(GV, D.getLocation(), OS.str(), D.getType(), IsDynInit);
67 }
68 
disableSanitizerForGlobal(llvm::GlobalVariable * GV)69 void SanitizerMetadata::disableSanitizerForGlobal(llvm::GlobalVariable *GV) {
70   // For now, just make sure the global is not modified by the ASan
71   // instrumentation.
72   if (CGM.getLangOpts().Sanitize.hasOneOf(SanitizerKind::Address |
73                                           SanitizerKind::KernelAddress))
74     reportGlobalToASan(GV, SourceLocation(), "", QualType(), false, true);
75 }
76 
disableSanitizerForInstruction(llvm::Instruction * I)77 void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
78   I->setMetadata(CGM.getModule().getMDKindID("nosanitize"),
79                  llvm::MDNode::get(CGM.getLLVMContext(), None));
80 }
81 
getLocationMetadata(SourceLocation Loc)82 llvm::MDNode *SanitizerMetadata::getLocationMetadata(SourceLocation Loc) {
83   PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc);
84   if (!PLoc.isValid())
85     return nullptr;
86   llvm::LLVMContext &VMContext = CGM.getLLVMContext();
87   llvm::Metadata *LocMetadata[] = {
88       llvm::MDString::get(VMContext, PLoc.getFilename()),
89       llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
90           llvm::Type::getInt32Ty(VMContext), PLoc.getLine())),
91       llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
92           llvm::Type::getInt32Ty(VMContext), PLoc.getColumn())),
93   };
94   return llvm::MDNode::get(VMContext, LocMetadata);
95 }
96