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DataFlowSanitizer.cpp
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DataFlowSanitizer.cpp
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//===- DataFlowSanitizer.cpp - dynamic data flow analysis -----------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
/// \file
/// This file is a part of DataFlowSanitizer, a generalised dynamic data flow
/// analysis.
///
/// Unlike other Sanitizer tools, this tool is not designed to detect a specific
/// class of bugs on its own. Instead, it provides a generic dynamic data flow
/// analysis framework to be used by clients to help detect application-specific
/// issues within their own code.
///
/// The analysis is based on automatic propagation of data flow labels (also
/// known as taint labels) through a program as it performs computation.
///
/// Each byte of application memory is backed by a shadow memory byte. The
/// shadow byte can represent up to 8 labels. On Linux/x86_64, memory is then
/// laid out as follows:
///
/// +--------------------+ 0x800000000000 (top of memory)
/// | application memory |
/// +--------------------+ 0x700000008000 (kAppAddr)
/// | |
/// | unused |
/// | |
/// +--------------------+ 0x300000000000 (kUnusedAddr)
/// | origin |
/// +--------------------+ 0x200000008000 (kOriginAddr)
/// | unused |
/// +--------------------+ 0x200000000000
/// | shadow memory |
/// +--------------------+ 0x100000008000 (kShadowAddr)
/// | unused |
/// +--------------------+ 0x000000010000
/// | reserved by kernel |
/// +--------------------+ 0x000000000000
///
///
/// To derive a shadow memory address from an application memory address, bits
/// 45-46 are cleared to bring the address into the range
/// [0x100000008000,0x200000000000). See the function
/// DataFlowSanitizer::getShadowAddress below.
///
/// For more information, please refer to the design document:
/// http://clang.llvm.org/docs/DataFlowSanitizerDesign.html
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Instrumentation/DataFlowSanitizer.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/iterator.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Argument.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/InstVisitor.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Alignment.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/SpecialCaseList.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <iterator>
#include <memory>
#include <set>
#include <string>
#include <utility>
#include <vector>
using namespace llvm;
// This must be consistent with ShadowWidthBits.
static const Align ShadowTLSAlignment = Align(2);
static const Align MinOriginAlignment = Align(4);
// The size of TLS variables. These constants must be kept in sync with the ones
// in dfsan.cpp.
static const unsigned ArgTLSSize = 800;
static const unsigned RetvalTLSSize = 800;
// External symbol to be used when generating the shadow address for
// architectures with multiple VMAs. Instead of using a constant integer
// the runtime will set the external mask based on the VMA range.
const char DFSanExternShadowPtrMask[] = "__dfsan_shadow_ptr_mask";
// The -dfsan-preserve-alignment flag controls whether this pass assumes that
// alignment requirements provided by the input IR are correct. For example,
// if the input IR contains a load with alignment 8, this flag will cause
// the shadow load to have alignment 16. This flag is disabled by default as
// we have unfortunately encountered too much code (including Clang itself;
// see PR14291) which performs misaligned access.
static cl::opt<bool> ClPreserveAlignment(
"dfsan-preserve-alignment",
cl::desc("respect alignment requirements provided by input IR"), cl::Hidden,
cl::init(false));
// The ABI list files control how shadow parameters are passed. The pass treats
// every function labelled "uninstrumented" in the ABI list file as conforming
// to the "native" (i.e. unsanitized) ABI. Unless the ABI list contains
// additional annotations for those functions, a call to one of those functions
// will produce a warning message, as the labelling behaviour of the function is
// unknown. The other supported annotations are "functional" and "discard",
// which are described below under DataFlowSanitizer::WrapperKind.
static cl::list<std::string> ClABIListFiles(
"dfsan-abilist",
cl::desc("File listing native ABI functions and how the pass treats them"),
cl::Hidden);
// Controls whether the pass uses IA_Args or IA_TLS as the ABI for instrumented
// functions (see DataFlowSanitizer::InstrumentedABI below).
static cl::opt<bool>
ClArgsABI("dfsan-args-abi",
cl::desc("Use the argument ABI rather than the TLS ABI"),
cl::Hidden);
// Controls whether the pass includes or ignores the labels of pointers in load
// instructions.
static cl::opt<bool> ClCombinePointerLabelsOnLoad(
"dfsan-combine-pointer-labels-on-load",
cl::desc("Combine the label of the pointer with the label of the data when "
"loading from memory."),
cl::Hidden, cl::init(true));
// Controls whether the pass includes or ignores the labels of pointers in
// stores instructions.
static cl::opt<bool> ClCombinePointerLabelsOnStore(
"dfsan-combine-pointer-labels-on-store",
cl::desc("Combine the label of the pointer with the label of the data when "
"storing in memory."),
cl::Hidden, cl::init(false));
// Controls whether the pass propagates labels of offsets in GEP instructions.
static cl::opt<bool> ClCombineOffsetLabelsOnGEP(
"dfsan-combine-offset-labels-on-gep",
cl::desc(
"Combine the label of the offset with the label of the pointer when "
"doing pointer arithmetic."),
cl::Hidden, cl::init(true));
static cl::opt<bool> ClDebugNonzeroLabels(
"dfsan-debug-nonzero-labels",
cl::desc("Insert calls to __dfsan_nonzero_label on observing a parameter, "
"load or return with a nonzero label"),
cl::Hidden);
// Experimental feature that inserts callbacks for certain data events.
// Currently callbacks are only inserted for loads, stores, memory transfers
// (i.e. memcpy and memmove), and comparisons.
//
// If this flag is set to true, the user must provide definitions for the
// following callback functions:
// void __dfsan_load_callback(dfsan_label Label, void* addr);
// void __dfsan_store_callback(dfsan_label Label, void* addr);
// void __dfsan_mem_transfer_callback(dfsan_label *Start, size_t Len);
// void __dfsan_cmp_callback(dfsan_label CombinedLabel);
static cl::opt<bool> ClEventCallbacks(
"dfsan-event-callbacks",
cl::desc("Insert calls to __dfsan_*_callback functions on data events."),
cl::Hidden, cl::init(false));
// Controls whether the pass tracks the control flow of select instructions.
static cl::opt<bool> ClTrackSelectControlFlow(
"dfsan-track-select-control-flow",
cl::desc("Propagate labels from condition values of select instructions "
"to results."),
cl::Hidden, cl::init(true));
// TODO: This default value follows MSan. DFSan may use a different value.
static cl::opt<int> ClInstrumentWithCallThreshold(
"dfsan-instrument-with-call-threshold",
cl::desc("If the function being instrumented requires more than "
"this number of origin stores, use callbacks instead of "
"inline checks (-1 means never use callbacks)."),
cl::Hidden, cl::init(3500));
// Controls how to track origins.
// * 0: do not track origins.
// * 1: track origins at memory store operations.
// * 2: track origins at memory load and store operations.
// TODO: track callsites.
static cl::opt<int> ClTrackOrigins("dfsan-track-origins",
cl::desc("Track origins of labels"),
cl::Hidden, cl::init(0));
static StringRef getGlobalTypeString(const GlobalValue &G) {
// Types of GlobalVariables are always pointer types.
Type *GType = G.getValueType();
// For now we support excluding struct types only.
if (StructType *SGType = dyn_cast<StructType>(GType)) {
if (!SGType->isLiteral())
return SGType->getName();
}
return "<unknown type>";
}
namespace {
class DFSanABIList {
std::unique_ptr<SpecialCaseList> SCL;
public:
DFSanABIList() = default;
void set(std::unique_ptr<SpecialCaseList> List) { SCL = std::move(List); }
/// Returns whether either this function or its source file are listed in the
/// given category.
bool isIn(const Function &F, StringRef Category) const {
return isIn(*F.getParent(), Category) ||
SCL->inSection("dataflow", "fun", F.getName(), Category);
}
/// Returns whether this global alias is listed in the given category.
///
/// If GA aliases a function, the alias's name is matched as a function name
/// would be. Similarly, aliases of globals are matched like globals.
bool isIn(const GlobalAlias &GA, StringRef Category) const {
if (isIn(*GA.getParent(), Category))
return true;
if (isa<FunctionType>(GA.getValueType()))
return SCL->inSection("dataflow", "fun", GA.getName(), Category);
return SCL->inSection("dataflow", "global", GA.getName(), Category) ||
SCL->inSection("dataflow", "type", getGlobalTypeString(GA),
Category);
}
/// Returns whether this module is listed in the given category.
bool isIn(const Module &M, StringRef Category) const {
return SCL->inSection("dataflow", "src", M.getModuleIdentifier(), Category);
}
};
/// TransformedFunction is used to express the result of transforming one
/// function type into another. This struct is immutable. It holds metadata
/// useful for updating calls of the old function to the new type.
struct TransformedFunction {
TransformedFunction(FunctionType *OriginalType, FunctionType *TransformedType,
std::vector<unsigned> ArgumentIndexMapping)
: OriginalType(OriginalType), TransformedType(TransformedType),
ArgumentIndexMapping(ArgumentIndexMapping) {}
// Disallow copies.
TransformedFunction(const TransformedFunction &) = delete;
TransformedFunction &operator=(const TransformedFunction &) = delete;
// Allow moves.
TransformedFunction(TransformedFunction &&) = default;
TransformedFunction &operator=(TransformedFunction &&) = default;
/// Type of the function before the transformation.
FunctionType *OriginalType;
/// Type of the function after the transformation.
FunctionType *TransformedType;
/// Transforming a function may change the position of arguments. This
/// member records the mapping from each argument's old position to its new
/// position. Argument positions are zero-indexed. If the transformation
/// from F to F' made the first argument of F into the third argument of F',
/// then ArgumentIndexMapping[0] will equal 2.
std::vector<unsigned> ArgumentIndexMapping;
};
/// Given function attributes from a call site for the original function,
/// return function attributes appropriate for a call to the transformed
/// function.
AttributeList
transformFunctionAttributes(const TransformedFunction &TransformedFunction,
LLVMContext &Ctx, AttributeList CallSiteAttrs) {
// Construct a vector of AttributeSet for each function argument.
std::vector<llvm::AttributeSet> ArgumentAttributes(
TransformedFunction.TransformedType->getNumParams());
// Copy attributes from the parameter of the original function to the
// transformed version. 'ArgumentIndexMapping' holds the mapping from
// old argument position to new.
for (unsigned I = 0, IE = TransformedFunction.ArgumentIndexMapping.size();
I < IE; ++I) {
unsigned TransformedIndex = TransformedFunction.ArgumentIndexMapping[I];
ArgumentAttributes[TransformedIndex] = CallSiteAttrs.getParamAttributes(I);
}
// Copy annotations on varargs arguments.
for (unsigned I = TransformedFunction.OriginalType->getNumParams(),
IE = CallSiteAttrs.getNumAttrSets();
I < IE; ++I) {
ArgumentAttributes.push_back(CallSiteAttrs.getParamAttributes(I));
}
return AttributeList::get(Ctx, CallSiteAttrs.getFnAttributes(),
CallSiteAttrs.getRetAttributes(),
llvm::makeArrayRef(ArgumentAttributes));
}
class DataFlowSanitizer {
friend struct DFSanFunction;
friend class DFSanVisitor;
enum { ShadowWidthBits = 8, ShadowWidthBytes = ShadowWidthBits / 8 };
enum { OriginWidthBits = 32, OriginWidthBytes = OriginWidthBits / 8 };
/// Which ABI should be used for instrumented functions?
enum InstrumentedABI {
/// Argument and return value labels are passed through additional
/// arguments and by modifying the return type.
IA_Args,
/// Argument and return value labels are passed through TLS variables
/// __dfsan_arg_tls and __dfsan_retval_tls.
IA_TLS
};
/// How should calls to uninstrumented functions be handled?
enum WrapperKind {
/// This function is present in an uninstrumented form but we don't know
/// how it should be handled. Print a warning and call the function anyway.
/// Don't label the return value.
WK_Warning,
/// This function does not write to (user-accessible) memory, and its return
/// value is unlabelled.
WK_Discard,
/// This function does not write to (user-accessible) memory, and the label
/// of its return value is the union of the label of its arguments.
WK_Functional,
/// Instead of calling the function, a custom wrapper __dfsw_F is called,
/// where F is the name of the function. This function may wrap the
/// original function or provide its own implementation. This is similar to
/// the IA_Args ABI, except that IA_Args uses a struct return type to
/// pass the return value shadow in a register, while WK_Custom uses an
/// extra pointer argument to return the shadow. This allows the wrapped
/// form of the function type to be expressed in C.
WK_Custom
};
Module *Mod;
LLVMContext *Ctx;
Type *Int8Ptr;
IntegerType *OriginTy;
PointerType *OriginPtrTy;
ConstantInt *ZeroOrigin;
/// The shadow type for all primitive types and vector types.
IntegerType *PrimitiveShadowTy;
PointerType *PrimitiveShadowPtrTy;
IntegerType *IntptrTy;
ConstantInt *ZeroPrimitiveShadow;
ConstantInt *ShadowPtrMask;
ConstantInt *ShadowBase;
ConstantInt *OriginBase;
Constant *ArgTLS;
ArrayType *ArgOriginTLSTy;
Constant *ArgOriginTLS;
Constant *RetvalTLS;
Constant *RetvalOriginTLS;
Constant *ExternalShadowMask;
FunctionType *DFSanUnionLoadFnTy;
FunctionType *DFSanLoadLabelAndOriginFnTy;
FunctionType *DFSanUnimplementedFnTy;
FunctionType *DFSanSetLabelFnTy;
FunctionType *DFSanNonzeroLabelFnTy;
FunctionType *DFSanVarargWrapperFnTy;
FunctionType *DFSanCmpCallbackFnTy;
FunctionType *DFSanLoadStoreCallbackFnTy;
FunctionType *DFSanMemTransferCallbackFnTy;
FunctionType *DFSanChainOriginFnTy;
FunctionType *DFSanChainOriginIfTaintedFnTy;
FunctionType *DFSanMemOriginTransferFnTy;
FunctionType *DFSanMaybeStoreOriginFnTy;
FunctionCallee DFSanUnionLoadFn;
FunctionCallee DFSanLoadLabelAndOriginFn;
FunctionCallee DFSanUnimplementedFn;
FunctionCallee DFSanSetLabelFn;
FunctionCallee DFSanNonzeroLabelFn;
FunctionCallee DFSanVarargWrapperFn;
FunctionCallee DFSanLoadCallbackFn;
FunctionCallee DFSanStoreCallbackFn;
FunctionCallee DFSanMemTransferCallbackFn;
FunctionCallee DFSanCmpCallbackFn;
FunctionCallee DFSanChainOriginFn;
FunctionCallee DFSanChainOriginIfTaintedFn;
FunctionCallee DFSanMemOriginTransferFn;
FunctionCallee DFSanMaybeStoreOriginFn;
SmallPtrSet<Value *, 16> DFSanRuntimeFunctions;
MDNode *ColdCallWeights;
MDNode *OriginStoreWeights;
DFSanABIList ABIList;
DenseMap<Value *, Function *> UnwrappedFnMap;
AttrBuilder ReadOnlyNoneAttrs;
bool DFSanRuntimeShadowMask = false;
Value *getShadowOffset(Value *Addr, IRBuilder<> &IRB);
Value *getShadowAddress(Value *Addr, Instruction *Pos);
Value *getShadowAddress(Value *Addr, Instruction *Pos, Value *ShadowOffset);
std::pair<Value *, Value *>
getShadowOriginAddress(Value *Addr, Align InstAlignment, Instruction *Pos);
bool isInstrumented(const Function *F);
bool isInstrumented(const GlobalAlias *GA);
FunctionType *getArgsFunctionType(FunctionType *T);
FunctionType *getTrampolineFunctionType(FunctionType *T);
TransformedFunction getCustomFunctionType(FunctionType *T);
InstrumentedABI getInstrumentedABI();
WrapperKind getWrapperKind(Function *F);
void addGlobalNamePrefix(GlobalValue *GV);
Function *buildWrapperFunction(Function *F, StringRef NewFName,
GlobalValue::LinkageTypes NewFLink,
FunctionType *NewFT);
Constant *getOrBuildTrampolineFunction(FunctionType *FT, StringRef FName);
void initializeCallbackFunctions(Module &M);
void initializeRuntimeFunctions(Module &M);
void injectMetadataGlobals(Module &M);
bool init(Module &M);
/// Advances \p OriginAddr to point to the next 32-bit origin and then loads
/// from it. Returns the origin's loaded value.
Value *loadNextOrigin(Instruction *Pos, Align OriginAlign,
Value **OriginAddr);
/// Returns whether the given load byte size is amenable to inlined
/// optimization patterns.
bool hasLoadSizeForFastPath(uint64_t Size);
/// Returns whether the pass tracks origins. Supports only TLS ABI mode.
bool shouldTrackOrigins();
/// Returns whether the pass tracks labels for struct fields and array
/// indices. Supports only TLS ABI mode.
bool shouldTrackFieldsAndIndices();
/// Returns a zero constant with the shadow type of OrigTy.
///
/// getZeroShadow({T1,T2,...}) = {getZeroShadow(T1),getZeroShadow(T2,...}
/// getZeroShadow([n x T]) = [n x getZeroShadow(T)]
/// getZeroShadow(other type) = i16(0)
///
/// Note that a zero shadow is always i16(0) when shouldTrackFieldsAndIndices
/// returns false.
Constant *getZeroShadow(Type *OrigTy);
/// Returns a zero constant with the shadow type of V's type.
Constant *getZeroShadow(Value *V);
/// Checks if V is a zero shadow.
bool isZeroShadow(Value *V);
/// Returns the shadow type of OrigTy.
///
/// getShadowTy({T1,T2,...}) = {getShadowTy(T1),getShadowTy(T2),...}
/// getShadowTy([n x T]) = [n x getShadowTy(T)]
/// getShadowTy(other type) = i16
///
/// Note that a shadow type is always i16 when shouldTrackFieldsAndIndices
/// returns false.
Type *getShadowTy(Type *OrigTy);
/// Returns the shadow type of of V's type.
Type *getShadowTy(Value *V);
const uint64_t NumOfElementsInArgOrgTLS = ArgTLSSize / OriginWidthBytes;
public:
DataFlowSanitizer(const std::vector<std::string> &ABIListFiles);
bool runImpl(Module &M);
};
struct DFSanFunction {
DataFlowSanitizer &DFS;
Function *F;
DominatorTree DT;
DataFlowSanitizer::InstrumentedABI IA;
bool IsNativeABI;
AllocaInst *LabelReturnAlloca = nullptr;
AllocaInst *OriginReturnAlloca = nullptr;
DenseMap<Value *, Value *> ValShadowMap;
DenseMap<Value *, Value *> ValOriginMap;
DenseMap<AllocaInst *, AllocaInst *> AllocaShadowMap;
DenseMap<AllocaInst *, AllocaInst *> AllocaOriginMap;
struct PHIFixupElement {
PHINode *Phi;
PHINode *ShadowPhi;
PHINode *OriginPhi;
};
std::vector<PHIFixupElement> PHIFixups;
DenseSet<Instruction *> SkipInsts;
std::vector<Value *> NonZeroChecks;
struct CachedShadow {
BasicBlock *Block; // The block where Shadow is defined.
Value *Shadow;
};
/// Maps a value to its latest shadow value in terms of domination tree.
DenseMap<std::pair<Value *, Value *>, CachedShadow> CachedShadows;
/// Maps a value to its latest collapsed shadow value it was converted to in
/// terms of domination tree. When ClDebugNonzeroLabels is on, this cache is
/// used at a post process where CFG blocks are split. So it does not cache
/// BasicBlock like CachedShadows, but uses domination between values.
DenseMap<Value *, Value *> CachedCollapsedShadows;
DenseMap<Value *, std::set<Value *>> ShadowElements;
DFSanFunction(DataFlowSanitizer &DFS, Function *F, bool IsNativeABI)
: DFS(DFS), F(F), IA(DFS.getInstrumentedABI()), IsNativeABI(IsNativeABI) {
DT.recalculate(*F);
}
/// Computes the shadow address for a given function argument.
///
/// Shadow = ArgTLS+ArgOffset.
Value *getArgTLS(Type *T, unsigned ArgOffset, IRBuilder<> &IRB);
/// Computes the shadow address for a return value.
Value *getRetvalTLS(Type *T, IRBuilder<> &IRB);
/// Computes the origin address for a given function argument.
///
/// Origin = ArgOriginTLS[ArgNo].
Value *getArgOriginTLS(unsigned ArgNo, IRBuilder<> &IRB);
/// Computes the origin address for a return value.
Value *getRetvalOriginTLS();
Value *getOrigin(Value *V);
void setOrigin(Instruction *I, Value *Origin);
/// Generates IR to compute the origin of the last operand with a taint label.
Value *combineOperandOrigins(Instruction *Inst);
/// Before the instruction Pos, generates IR to compute the last origin with a
/// taint label. Labels and origins are from vectors Shadows and Origins
/// correspondingly. The generated IR is like
/// Sn-1 != Zero ? On-1: ... S2 != Zero ? O2: S1 != Zero ? O1: O0
/// When Zero is nullptr, it uses ZeroPrimitiveShadow. Otherwise it can be
/// zeros with other bitwidths.
Value *combineOrigins(const std::vector<Value *> &Shadows,
const std::vector<Value *> &Origins, Instruction *Pos,
ConstantInt *Zero = nullptr);
Value *getShadow(Value *V);
void setShadow(Instruction *I, Value *Shadow);
/// Generates IR to compute the union of the two given shadows, inserting it
/// before Pos. The combined value is with primitive type.
Value *combineShadows(Value *V1, Value *V2, Instruction *Pos);
/// Combines the shadow values of V1 and V2, then converts the combined value
/// with primitive type into a shadow value with the original type T.
Value *combineShadowsThenConvert(Type *T, Value *V1, Value *V2,
Instruction *Pos);
Value *combineOperandShadows(Instruction *Inst);
/// Generates IR to load shadow and origin corresponding to bytes [\p
/// Addr, \p Addr + \p Size), where addr has alignment \p
/// InstAlignment, and take the union of each of those shadows. The returned
/// shadow always has primitive type.
///
/// When tracking loads is enabled, the returned origin is a chain at the
/// current stack if the returned shadow is tainted.
std::pair<Value *, Value *> loadShadowOrigin(Value *Addr, uint64_t Size,
Align InstAlignment,
Instruction *Pos);
void storePrimitiveShadowOrigin(Value *Addr, uint64_t Size,
Align InstAlignment, Value *PrimitiveShadow,
Value *Origin, Instruction *Pos);
/// Applies PrimitiveShadow to all primitive subtypes of T, returning
/// the expanded shadow value.
///
/// EFP({T1,T2, ...}, PS) = {EFP(T1,PS),EFP(T2,PS),...}
/// EFP([n x T], PS) = [n x EFP(T,PS)]
/// EFP(other types, PS) = PS
Value *expandFromPrimitiveShadow(Type *T, Value *PrimitiveShadow,
Instruction *Pos);
/// Collapses Shadow into a single primitive shadow value, unioning all
/// primitive shadow values in the process. Returns the final primitive
/// shadow value.
///
/// CTP({V1,V2, ...}) = UNION(CFP(V1,PS),CFP(V2,PS),...)
/// CTP([V1,V2,...]) = UNION(CFP(V1,PS),CFP(V2,PS),...)
/// CTP(other types, PS) = PS
Value *collapseToPrimitiveShadow(Value *Shadow, Instruction *Pos);
void storeZeroPrimitiveShadow(Value *Addr, uint64_t Size, Align ShadowAlign,
Instruction *Pos);
Align getShadowAlign(Align InstAlignment);
private:
/// Collapses the shadow with aggregate type into a single primitive shadow
/// value.
template <class AggregateType>
Value *collapseAggregateShadow(AggregateType *AT, Value *Shadow,
IRBuilder<> &IRB);
Value *collapseToPrimitiveShadow(Value *Shadow, IRBuilder<> &IRB);
/// Returns the shadow value of an argument A.
Value *getShadowForTLSArgument(Argument *A);
/// The fast path of loading shadows.
std::pair<Value *, Value *>
loadShadowFast(Value *ShadowAddr, Value *OriginAddr, uint64_t Size,
Align ShadowAlign, Align OriginAlign, Value *FirstOrigin,
Instruction *Pos);
Align getOriginAlign(Align InstAlignment);
/// Because 4 contiguous bytes share one 4-byte origin, the most accurate load
/// is __dfsan_load_label_and_origin. This function returns the union of all
/// labels and the origin of the first taint label. However this is an
/// additional call with many instructions. To ensure common cases are fast,
/// checks if it is possible to load labels and origins without using the
/// callback function.
///
/// When enabling tracking load instructions, we always use
/// __dfsan_load_label_and_origin to reduce code size.
bool useCallbackLoadLabelAndOrigin(uint64_t Size, Align InstAlignment);
/// Returns a chain at the current stack with previous origin V.
Value *updateOrigin(Value *V, IRBuilder<> &IRB);
/// Returns a chain at the current stack with previous origin V if Shadow is
/// tainted.
Value *updateOriginIfTainted(Value *Shadow, Value *Origin, IRBuilder<> &IRB);
/// Creates an Intptr = Origin | Origin << 32 if Intptr's size is 64. Returns
/// Origin otherwise.
Value *originToIntptr(IRBuilder<> &IRB, Value *Origin);
/// Stores Origin into the address range [StoreOriginAddr, StoreOriginAddr +
/// Size).
void paintOrigin(IRBuilder<> &IRB, Value *Origin, Value *StoreOriginAddr,
uint64_t StoreOriginSize, Align Alignment);
/// Stores Origin in terms of its Shadow value.
/// * Do not write origins for zero shadows because we do not trace origins
/// for untainted sinks.
/// * Use __dfsan_maybe_store_origin if there are too many origin store
/// instrumentations.
void storeOrigin(Instruction *Pos, Value *Addr, uint64_t Size, Value *Shadow,
Value *Origin, Value *StoreOriginAddr, Align InstAlignment);
/// Convert a scalar value to an i1 by comparing with 0.
Value *convertToBool(Value *V, IRBuilder<> &IRB, const Twine &Name = "");
bool shouldInstrumentWithCall();
/// Generates IR to load shadow and origin corresponding to bytes [\p
/// Addr, \p Addr + \p Size), where addr has alignment \p
/// InstAlignment, and take the union of each of those shadows. The returned
/// shadow always has primitive type.
std::pair<Value *, Value *>
loadShadowOriginSansLoadTracking(Value *Addr, uint64_t Size,
Align InstAlignment, Instruction *Pos);
int NumOriginStores = 0;
};
class DFSanVisitor : public InstVisitor<DFSanVisitor> {
public:
DFSanFunction &DFSF;
DFSanVisitor(DFSanFunction &DFSF) : DFSF(DFSF) {}
const DataLayout &getDataLayout() const {
return DFSF.F->getParent()->getDataLayout();
}
// Combines shadow values and origins for all of I's operands.
void visitInstOperands(Instruction &I);
void visitUnaryOperator(UnaryOperator &UO);
void visitBinaryOperator(BinaryOperator &BO);
void visitBitCastInst(BitCastInst &BCI);
void visitCastInst(CastInst &CI);
void visitCmpInst(CmpInst &CI);
void visitLandingPadInst(LandingPadInst &LPI);
void visitGetElementPtrInst(GetElementPtrInst &GEPI);
void visitLoadInst(LoadInst &LI);
void visitStoreInst(StoreInst &SI);
void visitAtomicRMWInst(AtomicRMWInst &I);
void visitAtomicCmpXchgInst(AtomicCmpXchgInst &I);
void visitReturnInst(ReturnInst &RI);
void visitCallBase(CallBase &CB);
void visitPHINode(PHINode &PN);
void visitExtractElementInst(ExtractElementInst &I);
void visitInsertElementInst(InsertElementInst &I);
void visitShuffleVectorInst(ShuffleVectorInst &I);
void visitExtractValueInst(ExtractValueInst &I);
void visitInsertValueInst(InsertValueInst &I);
void visitAllocaInst(AllocaInst &I);
void visitSelectInst(SelectInst &I);
void visitMemSetInst(MemSetInst &I);
void visitMemTransferInst(MemTransferInst &I);
private:
void visitCASOrRMW(Align InstAlignment, Instruction &I);
// Returns false when this is an invoke of a custom function.
bool visitWrappedCallBase(Function &F, CallBase &CB);
// Combines origins for all of I's operands.
void visitInstOperandOrigins(Instruction &I);
void addShadowArguments(Function &F, CallBase &CB, std::vector<Value *> &Args,
IRBuilder<> &IRB);
void addOriginArguments(Function &F, CallBase &CB, std::vector<Value *> &Args,
IRBuilder<> &IRB);
};
} // end anonymous namespace
DataFlowSanitizer::DataFlowSanitizer(
const std::vector<std::string> &ABIListFiles) {
std::vector<std::string> AllABIListFiles(std::move(ABIListFiles));
llvm::append_range(AllABIListFiles, ClABIListFiles);
// FIXME: should we propagate vfs::FileSystem to this constructor?
ABIList.set(
SpecialCaseList::createOrDie(AllABIListFiles, *vfs::getRealFileSystem()));
}
FunctionType *DataFlowSanitizer::getArgsFunctionType(FunctionType *T) {
SmallVector<Type *, 4> ArgTypes(T->param_begin(), T->param_end());
ArgTypes.append(T->getNumParams(), PrimitiveShadowTy);
if (T->isVarArg())
ArgTypes.push_back(PrimitiveShadowPtrTy);
Type *RetType = T->getReturnType();
if (!RetType->isVoidTy())
RetType = StructType::get(RetType, PrimitiveShadowTy);
return FunctionType::get(RetType, ArgTypes, T->isVarArg());
}
FunctionType *DataFlowSanitizer::getTrampolineFunctionType(FunctionType *T) {
assert(!T->isVarArg());
SmallVector<Type *, 4> ArgTypes;
ArgTypes.push_back(T->getPointerTo());
ArgTypes.append(T->param_begin(), T->param_end());
ArgTypes.append(T->getNumParams(), PrimitiveShadowTy);
Type *RetType = T->getReturnType();
if (!RetType->isVoidTy())
ArgTypes.push_back(PrimitiveShadowPtrTy);
if (shouldTrackOrigins()) {
ArgTypes.append(T->getNumParams(), OriginTy);
if (!RetType->isVoidTy())
ArgTypes.push_back(OriginPtrTy);
}
return FunctionType::get(T->getReturnType(), ArgTypes, false);
}
TransformedFunction DataFlowSanitizer::getCustomFunctionType(FunctionType *T) {
SmallVector<Type *, 4> ArgTypes;
// Some parameters of the custom function being constructed are
// parameters of T. Record the mapping from parameters of T to
// parameters of the custom function, so that parameter attributes
// at call sites can be updated.
std::vector<unsigned> ArgumentIndexMapping;
for (unsigned I = 0, E = T->getNumParams(); I != E; ++I) {
Type *ParamType = T->getParamType(I);
FunctionType *FT;
if (isa<PointerType>(ParamType) &&
(FT = dyn_cast<FunctionType>(ParamType->getPointerElementType()))) {
ArgumentIndexMapping.push_back(ArgTypes.size());
ArgTypes.push_back(getTrampolineFunctionType(FT)->getPointerTo());
ArgTypes.push_back(Type::getInt8PtrTy(*Ctx));
} else {
ArgumentIndexMapping.push_back(ArgTypes.size());
ArgTypes.push_back(ParamType);
}
}
for (unsigned I = 0, E = T->getNumParams(); I != E; ++I)
ArgTypes.push_back(PrimitiveShadowTy);
if (T->isVarArg())
ArgTypes.push_back(PrimitiveShadowPtrTy);
Type *RetType = T->getReturnType();
if (!RetType->isVoidTy())
ArgTypes.push_back(PrimitiveShadowPtrTy);
if (shouldTrackOrigins()) {
for (unsigned I = 0, E = T->getNumParams(); I != E; ++I)
ArgTypes.push_back(OriginTy);
if (T->isVarArg())
ArgTypes.push_back(OriginPtrTy);
if (!RetType->isVoidTy())
ArgTypes.push_back(OriginPtrTy);
}
return TransformedFunction(
T, FunctionType::get(T->getReturnType(), ArgTypes, T->isVarArg()),
ArgumentIndexMapping);
}
bool DataFlowSanitizer::isZeroShadow(Value *V) {
if (!shouldTrackFieldsAndIndices())
return ZeroPrimitiveShadow == V;
Type *T = V->getType();
if (!isa<ArrayType>(T) && !isa<StructType>(T)) {
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
return CI->isZero();
return false;
}
return isa<ConstantAggregateZero>(V);
}
bool DataFlowSanitizer::hasLoadSizeForFastPath(uint64_t Size) {
uint64_t ShadowSize = Size * ShadowWidthBytes;
return ShadowSize % 8 == 0 || ShadowSize == 4;
}
bool DataFlowSanitizer::shouldTrackOrigins() {
static const bool ShouldTrackOrigins =
ClTrackOrigins && getInstrumentedABI() == DataFlowSanitizer::IA_TLS;
return ShouldTrackOrigins;
}
bool DataFlowSanitizer::shouldTrackFieldsAndIndices() {
return getInstrumentedABI() == DataFlowSanitizer::IA_TLS;
}
Constant *DataFlowSanitizer::getZeroShadow(Type *OrigTy) {
if (!shouldTrackFieldsAndIndices())
return ZeroPrimitiveShadow;
if (!isa<ArrayType>(OrigTy) && !isa<StructType>(OrigTy))
return ZeroPrimitiveShadow;
Type *ShadowTy = getShadowTy(OrigTy);
return ConstantAggregateZero::get(ShadowTy);
}
Constant *DataFlowSanitizer::getZeroShadow(Value *V) {
return getZeroShadow(V->getType());
}
static Value *expandFromPrimitiveShadowRecursive(
Value *Shadow, SmallVector<unsigned, 4> &Indices, Type *SubShadowTy,
Value *PrimitiveShadow, IRBuilder<> &IRB) {
if (!isa<ArrayType>(SubShadowTy) && !isa<StructType>(SubShadowTy))
return IRB.CreateInsertValue(Shadow, PrimitiveShadow, Indices);
if (ArrayType *AT = dyn_cast<ArrayType>(SubShadowTy)) {
for (unsigned Idx = 0; Idx < AT->getNumElements(); Idx++) {
Indices.push_back(Idx);
Shadow = expandFromPrimitiveShadowRecursive(
Shadow, Indices, AT->getElementType(), PrimitiveShadow, IRB);
Indices.pop_back();
}
return Shadow;
}
if (StructType *ST = dyn_cast<StructType>(SubShadowTy)) {
for (unsigned Idx = 0; Idx < ST->getNumElements(); Idx++) {
Indices.push_back(Idx);
Shadow = expandFromPrimitiveShadowRecursive(
Shadow, Indices, ST->getElementType(Idx), PrimitiveShadow, IRB);
Indices.pop_back();
}
return Shadow;
}
llvm_unreachable("Unexpected shadow type");
}
bool DFSanFunction::shouldInstrumentWithCall() {
return ClInstrumentWithCallThreshold >= 0 &&
NumOriginStores >= ClInstrumentWithCallThreshold;
}
Value *DFSanFunction::expandFromPrimitiveShadow(Type *T, Value *PrimitiveShadow,
Instruction *Pos) {
Type *ShadowTy = DFS.getShadowTy(T);
if (!isa<ArrayType>(ShadowTy) && !isa<StructType>(ShadowTy))
return PrimitiveShadow;
if (DFS.isZeroShadow(PrimitiveShadow))
return DFS.getZeroShadow(ShadowTy);
IRBuilder<> IRB(Pos);
SmallVector<unsigned, 4> Indices;
Value *Shadow = UndefValue::get(ShadowTy);
Shadow = expandFromPrimitiveShadowRecursive(Shadow, Indices, ShadowTy,
PrimitiveShadow, IRB);
// Caches the primitive shadow value that built the shadow value.
CachedCollapsedShadows[Shadow] = PrimitiveShadow;
return Shadow;
}
template <class AggregateType>
Value *DFSanFunction::collapseAggregateShadow(AggregateType *AT, Value *Shadow,
IRBuilder<> &IRB) {
if (!AT->getNumElements())
return DFS.ZeroPrimitiveShadow;
Value *FirstItem = IRB.CreateExtractValue(Shadow, 0);
Value *Aggregator = collapseToPrimitiveShadow(FirstItem, IRB);
for (unsigned Idx = 1; Idx < AT->getNumElements(); Idx++) {
Value *ShadowItem = IRB.CreateExtractValue(Shadow, Idx);
Value *ShadowInner = collapseToPrimitiveShadow(ShadowItem, IRB);
Aggregator = IRB.CreateOr(Aggregator, ShadowInner);
}
return Aggregator;
}
Value *DFSanFunction::collapseToPrimitiveShadow(Value *Shadow,
IRBuilder<> &IRB) {
Type *ShadowTy = Shadow->getType();
if (!isa<ArrayType>(ShadowTy) && !isa<StructType>(ShadowTy))
return Shadow;
if (ArrayType *AT = dyn_cast<ArrayType>(ShadowTy))
return collapseAggregateShadow<>(AT, Shadow, IRB);
if (StructType *ST = dyn_cast<StructType>(ShadowTy))
return collapseAggregateShadow<>(ST, Shadow, IRB);
llvm_unreachable("Unexpected shadow type");
}
Value *DFSanFunction::collapseToPrimitiveShadow(Value *Shadow,
Instruction *Pos) {
Type *ShadowTy = Shadow->getType();
if (!isa<ArrayType>(ShadowTy) && !isa<StructType>(ShadowTy))
return Shadow;
assert(DFS.shouldTrackFieldsAndIndices());
// Checks if the cached collapsed shadow value dominates Pos.
Value *&CS = CachedCollapsedShadows[Shadow];
if (CS && DT.dominates(CS, Pos))
return CS;
IRBuilder<> IRB(Pos);
Value *PrimitiveShadow = collapseToPrimitiveShadow(Shadow, IRB);
// Caches the converted primitive shadow value.
CS = PrimitiveShadow;
return PrimitiveShadow;
}
Type *DataFlowSanitizer::getShadowTy(Type *OrigTy) {
if (!shouldTrackFieldsAndIndices())
return PrimitiveShadowTy;
if (!OrigTy->isSized())
return PrimitiveShadowTy;
if (isa<IntegerType>(OrigTy))
return PrimitiveShadowTy;
if (isa<VectorType>(OrigTy))
return PrimitiveShadowTy;
if (ArrayType *AT = dyn_cast<ArrayType>(OrigTy))
return ArrayType::get(getShadowTy(AT->getElementType()),
AT->getNumElements());
if (StructType *ST = dyn_cast<StructType>(OrigTy)) {
SmallVector<Type *, 4> Elements;