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c5e7f56249
Add "memtag" sanitizer that detects and mitigates stack memory issues using armv8.5 Memory Tagging Extension. It is similar in principle to HWASan, which is a software implementation of the same idea, but there are enough differencies to warrant a new sanitizer type IMHO. It is also expected to have very different performance properties. The new sanitizer does not have a runtime library (it may grow one later, along with a "debugging" mode). Similar to SafeStack and StackProtector, the instrumentation pass (in a follow up change) will be inserted in all cases, but will only affect functions marked with the new sanitize_memtag attribute. Reviewers: pcc, hctim, vitalybuka, ostannard Subscribers: srhines, mehdi_amini, javed.absar, kristof.beyls, hiraditya, cryptoad, steven_wu, dexonsmith, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D64169 llvm-svn: 366123
104 lines
4.2 KiB
C++
104 lines
4.2 KiB
C++
//===--- SanitizerMetadata.cpp - Blacklist for sanitizers -----------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// Class which emits metadata consumed by sanitizer instrumentation passes.
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//
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//===----------------------------------------------------------------------===//
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#include "SanitizerMetadata.h"
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#include "CodeGenModule.h"
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#include "clang/AST/Type.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/IR/Constants.h"
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using namespace clang;
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using namespace CodeGen;
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SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {}
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static bool isAsanHwasanOrMemTag(const SanitizerSet& SS) {
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return SS.hasOneOf(SanitizerKind::Address | SanitizerKind::KernelAddress |
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SanitizerKind::HWAddress | SanitizerKind::KernelHWAddress |
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SanitizerKind::MemTag);
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}
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void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
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SourceLocation Loc, StringRef Name,
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QualType Ty, bool IsDynInit,
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bool IsBlacklisted) {
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if (!isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize))
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return;
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IsDynInit &= !CGM.isInSanitizerBlacklist(GV, Loc, Ty, "init");
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IsBlacklisted |= CGM.isInSanitizerBlacklist(GV, Loc, Ty);
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llvm::Metadata *LocDescr = nullptr;
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llvm::Metadata *GlobalName = nullptr;
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llvm::LLVMContext &VMContext = CGM.getLLVMContext();
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if (!IsBlacklisted) {
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// Don't generate source location and global name if it is blacklisted -
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// it won't be instrumented anyway.
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LocDescr = getLocationMetadata(Loc);
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if (!Name.empty())
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GlobalName = llvm::MDString::get(VMContext, Name);
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}
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llvm::Metadata *GlobalMetadata[] = {
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llvm::ConstantAsMetadata::get(GV), LocDescr, GlobalName,
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llvm::ConstantAsMetadata::get(
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llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), IsDynInit)),
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llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
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llvm::Type::getInt1Ty(VMContext), IsBlacklisted))};
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llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalMetadata);
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llvm::NamedMDNode *AsanGlobals =
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CGM.getModule().getOrInsertNamedMetadata("llvm.asan.globals");
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AsanGlobals->addOperand(ThisGlobal);
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}
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void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
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const VarDecl &D, bool IsDynInit) {
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if (!isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize))
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return;
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std::string QualName;
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llvm::raw_string_ostream OS(QualName);
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D.printQualifiedName(OS);
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bool IsBlacklisted = false;
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for (auto Attr : D.specific_attrs<NoSanitizeAttr>())
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if (Attr->getMask() & SanitizerKind::Address)
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IsBlacklisted = true;
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reportGlobalToASan(GV, D.getLocation(), OS.str(), D.getType(), IsDynInit,
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IsBlacklisted);
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}
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void SanitizerMetadata::disableSanitizerForGlobal(llvm::GlobalVariable *GV) {
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// For now, just make sure the global is not modified by the ASan
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// instrumentation.
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if (isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize))
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reportGlobalToASan(GV, SourceLocation(), "", QualType(), false, true);
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}
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void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
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I->setMetadata(CGM.getModule().getMDKindID("nosanitize"),
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llvm::MDNode::get(CGM.getLLVMContext(), None));
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}
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llvm::MDNode *SanitizerMetadata::getLocationMetadata(SourceLocation Loc) {
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PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc);
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if (!PLoc.isValid())
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return nullptr;
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llvm::LLVMContext &VMContext = CGM.getLLVMContext();
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llvm::Metadata *LocMetadata[] = {
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llvm::MDString::get(VMContext, PLoc.getFilename()),
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llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
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llvm::Type::getInt32Ty(VMContext), PLoc.getLine())),
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llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
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llvm::Type::getInt32Ty(VMContext), PLoc.getColumn())),
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};
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return llvm::MDNode::get(VMContext, LocMetadata);
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}
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