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 "llvm/ADT/StringRef.h"
16 #include "llvm/IR/Constants.h"
17 
18 using namespace clang;
19 using namespace CodeGen;
20 
21 SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {}
22 
23 void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
24                                            SourceLocation Loc, StringRef Name,
25                                            bool IsDynInit, bool IsBlacklisted) {
26   if (!CGM.getLangOpts().Sanitize.Address)
27     return;
28   IsDynInit &= !CGM.getSanitizerBlacklist().isIn(*GV, "init");
29   IsBlacklisted |= CGM.getSanitizerBlacklist().isIn(*GV);
30 
31   llvm::Value *LocDescr = nullptr;
32   llvm::Value *GlobalName = nullptr;
33   llvm::LLVMContext &VMContext = CGM.getLLVMContext();
34   if (!IsBlacklisted) {
35     // Don't generate source location and global name if it is blacklisted -
36     // it won't be instrumented anyway.
37     LocDescr = getLocationMetadata(Loc);
38     if (!Name.empty())
39       GlobalName = llvm::MDString::get(VMContext, Name);
40   }
41 
42   llvm::Value *GlobalMetadata[] = {
43       GV, LocDescr, GlobalName,
44       llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), IsDynInit),
45       llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), IsBlacklisted)};
46 
47   llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalMetadata);
48   llvm::NamedMDNode *AsanGlobals =
49       CGM.getModule().getOrInsertNamedMetadata("llvm.asan.globals");
50   AsanGlobals->addOperand(ThisGlobal);
51 }
52 
53 void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
54                                            const VarDecl &D, bool IsDynInit) {
55   if (!CGM.getLangOpts().Sanitize.Address)
56     return;
57   std::string QualName;
58   llvm::raw_string_ostream OS(QualName);
59   D.printQualifiedName(OS);
60   reportGlobalToASan(GV, D.getLocation(), OS.str(), IsDynInit);
61 }
62 
63 void SanitizerMetadata::disableSanitizerForGlobal(llvm::GlobalVariable *GV) {
64   // For now, just make sure the global is not modified by the ASan
65   // instrumentation.
66   if (CGM.getLangOpts().Sanitize.Address)
67     reportGlobalToASan(GV, SourceLocation(), "", false, true);
68 }
69 
70 llvm::MDNode *SanitizerMetadata::getLocationMetadata(SourceLocation Loc) {
71   PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc);
72   if (!PLoc.isValid())
73     return nullptr;
74   llvm::LLVMContext &VMContext = CGM.getLLVMContext();
75   llvm::Value *LocMetadata[] = {
76       llvm::MDString::get(VMContext, PLoc.getFilename()),
77       llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), PLoc.getLine()),
78       llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
79                              PLoc.getColumn()),
80   };
81   return llvm::MDNode::get(VMContext, LocMetadata);
82 }
83