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/Type.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                                            QualType Ty, bool IsDynInit,
26                                            bool IsBlacklisted) {
27   if (!CGM.getLangOpts().Sanitize.hasOneOf(SanitizerKind::Address |
28                                            SanitizerKind::KernelAddress |
29                                            SanitizerKind::HWAddress |
30                                            SanitizerKind::KernelHWAddress))
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                                            SanitizerKind::KernelHWAddress))
65     return;
66   std::string QualName;
67   llvm::raw_string_ostream OS(QualName);
68   D.printQualifiedName(OS);
69 
70   bool IsBlacklisted = false;
71   for (auto Attr : D.specific_attrs<NoSanitizeAttr>())
72     if (Attr->getMask() & SanitizerKind::Address)
73       IsBlacklisted = true;
74   reportGlobalToASan(GV, D.getLocation(), OS.str(), D.getType(), IsDynInit,
75                      IsBlacklisted);
76 }
77 
78 void SanitizerMetadata::disableSanitizerForGlobal(llvm::GlobalVariable *GV) {
79   // For now, just make sure the global is not modified by the ASan
80   // instrumentation.
81   if (CGM.getLangOpts().Sanitize.hasOneOf(SanitizerKind::Address |
82                                           SanitizerKind::KernelAddress |
83                                           SanitizerKind::HWAddress |
84                                           SanitizerKind::KernelHWAddress))
85     reportGlobalToASan(GV, SourceLocation(), "", QualType(), false, true);
86 }
87 
88 void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
89   I->setMetadata(CGM.getModule().getMDKindID("nosanitize"),
90                  llvm::MDNode::get(CGM.getLLVMContext(), None));
91 }
92 
93 llvm::MDNode *SanitizerMetadata::getLocationMetadata(SourceLocation Loc) {
94   PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc);
95   if (!PLoc.isValid())
96     return nullptr;
97   llvm::LLVMContext &VMContext = CGM.getLLVMContext();
98   llvm::Metadata *LocMetadata[] = {
99       llvm::MDString::get(VMContext, PLoc.getFilename()),
100       llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
101           llvm::Type::getInt32Ty(VMContext), PLoc.getLine())),
102       llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
103           llvm::Type::getInt32Ty(VMContext), PLoc.getColumn())),
104   };
105   return llvm::MDNode::get(VMContext, LocMetadata);
106 }
107