SanitizerMetadata.cpp
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//===--- SanitizerMetadata.cpp - Blacklist for sanitizers -----------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Class which emits metadata consumed by sanitizer instrumentation passes.
//
//===----------------------------------------------------------------------===//
#include "SanitizerMetadata.h"
#include "CodeGenModule.h"
#include "clang/AST/Attr.h"
#include "clang/AST/Type.h"
#include "clang/Basic/SourceManager.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/IR/Constants.h"
using namespace clang;
using namespace CodeGen;
SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {}
static bool isAsanHwasanOrMemTag(const SanitizerSet& SS) {
return SS.hasOneOf(SanitizerKind::Address | SanitizerKind::KernelAddress |
SanitizerKind::HWAddress | SanitizerKind::KernelHWAddress |
SanitizerKind::MemTag);
}
void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
SourceLocation Loc, StringRef Name,
QualType Ty, bool IsDynInit,
bool IsExcluded) {
if (!isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize))
return;
IsDynInit &= !CGM.isInSanitizerBlacklist(GV, Loc, Ty, "init");
IsExcluded |= CGM.isInSanitizerBlacklist(GV, Loc, Ty);
llvm::Metadata *LocDescr = nullptr;
llvm::Metadata *GlobalName = nullptr;
llvm::LLVMContext &VMContext = CGM.getLLVMContext();
if (!IsExcluded) {
// Don't generate source location and global name if it is blacklisted -
// it won't be instrumented anyway.
LocDescr = getLocationMetadata(Loc);
if (!Name.empty())
GlobalName = llvm::MDString::get(VMContext, Name);
}
llvm::Metadata *GlobalMetadata[] = {
llvm::ConstantAsMetadata::get(GV), LocDescr, GlobalName,
llvm::ConstantAsMetadata::get(
llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), IsDynInit)),
llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
llvm::Type::getInt1Ty(VMContext), IsExcluded))};
llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalMetadata);
llvm::NamedMDNode *AsanGlobals =
CGM.getModule().getOrInsertNamedMetadata("llvm.asan.globals");
AsanGlobals->addOperand(ThisGlobal);
}
void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
const VarDecl &D, bool IsDynInit) {
if (!isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize))
return;
std::string QualName;
llvm::raw_string_ostream OS(QualName);
D.printQualifiedName(OS);
bool IsExcluded = false;
for (auto Attr : D.specific_attrs<NoSanitizeAttr>())
if (Attr->getMask() & SanitizerKind::Address)
IsExcluded = true;
reportGlobalToASan(GV, D.getLocation(), OS.str(), D.getType(), IsDynInit,
IsExcluded);
}
void SanitizerMetadata::disableSanitizerForGlobal(llvm::GlobalVariable *GV) {
// For now, just make sure the global is not modified by the ASan
// instrumentation.
if (isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize))
reportGlobalToASan(GV, SourceLocation(), "", QualType(), false, true);
}
void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
I->setMetadata(CGM.getModule().getMDKindID("nosanitize"),
llvm::MDNode::get(CGM.getLLVMContext(), None));
}
llvm::MDNode *SanitizerMetadata::getLocationMetadata(SourceLocation Loc) {
PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc);
if (!PLoc.isValid())
return nullptr;
llvm::LLVMContext &VMContext = CGM.getLLVMContext();
llvm::Metadata *LocMetadata[] = {
llvm::MDString::get(VMContext, PLoc.getFilename()),
llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
llvm::Type::getInt32Ty(VMContext), PLoc.getLine())),
llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
llvm::Type::getInt32Ty(VMContext), PLoc.getColumn())),
};
return llvm::MDNode::get(VMContext, LocMetadata);
}