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1//===- FileAnalysis.h -------------------------------------------*- C++ -*-===//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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef LLVM_CFI_VERIFY_FILE_ANALYSIS_H10#define LLVM_CFI_VERIFY_FILE_ANALYSIS_H11 12#include "llvm/ADT/DenseMap.h"13#include "llvm/ADT/SmallSet.h"14#include "llvm/BinaryFormat/ELF.h"15#include "llvm/DebugInfo/Symbolize/Symbolize.h"16#include "llvm/MC/MCAsmInfo.h"17#include "llvm/MC/MCContext.h"18#include "llvm/MC/MCDisassembler/MCDisassembler.h"19#include "llvm/MC/MCInst.h"20#include "llvm/MC/MCInstPrinter.h"21#include "llvm/MC/MCInstrAnalysis.h"22#include "llvm/MC/MCInstrDesc.h"23#include "llvm/MC/MCInstrInfo.h"24#include "llvm/MC/MCObjectFileInfo.h"25#include "llvm/MC/MCRegisterInfo.h"26#include "llvm/MC/MCSubtargetInfo.h"27#include "llvm/MC/TargetRegistry.h"28#include "llvm/Object/Binary.h"29#include "llvm/Object/COFF.h"30#include "llvm/Object/ELFObjectFile.h"31#include "llvm/Object/ObjectFile.h"32#include "llvm/Support/Casting.h"33#include "llvm/Support/CommandLine.h"34#include "llvm/Support/Error.h"35#include "llvm/Support/MemoryBuffer.h"36#include "llvm/Support/TargetSelect.h"37#include "llvm/Support/raw_ostream.h"38 39#include <functional>40#include <set>41#include <string>42 43namespace llvm {44namespace cfi_verify {45 46struct GraphResult;47 48extern bool IgnoreDWARFFlag;49 50enum class CFIProtectionStatus {51 // This instruction is protected by CFI.52 PROTECTED,53 // The instruction is not an indirect control flow instruction, and thus54 // shouldn't be protected.55 FAIL_NOT_INDIRECT_CF,56 // There is a path to the instruction that was unexpected.57 FAIL_ORPHANS,58 // There is a path to the instruction from a conditional branch that does not59 // properly check the destination for this vcall/icall.60 FAIL_BAD_CONDITIONAL_BRANCH,61 // One of the operands of the indirect CF instruction is modified between the62 // CFI-check and execution.63 FAIL_REGISTER_CLOBBERED,64 // The instruction referenced does not exist. This normally indicates an65 // error in the program, where you try and validate a graph that was created66 // in a different FileAnalysis object.67 FAIL_INVALID_INSTRUCTION,68};69 70StringRef stringCFIProtectionStatus(CFIProtectionStatus Status);71 72// Disassembler and analysis tool for machine code files. Keeps track of non-73// sequential control flows, including indirect control flow instructions.74class FileAnalysis {75public:76 // A metadata struct for an instruction.77 struct Instr {78 uint64_t VMAddress; // Virtual memory address of this instruction.79 MCInst Instruction; // Instruction.80 uint64_t InstructionSize; // Size of this instruction.81 bool Valid; // Is this a valid instruction? If false, Instr::Instruction is82 // undefined.83 };84 85 // Construct a FileAnalysis from a file path.86 static Expected<FileAnalysis> Create(StringRef Filename);87 88 // Construct and take ownership of the supplied object. Do not use this89 // constructor, prefer to use FileAnalysis::Create instead.90 FileAnalysis(object::OwningBinary<object::Binary> Binary);91 FileAnalysis() = delete;92 FileAnalysis(const FileAnalysis &) = delete;93 FileAnalysis(FileAnalysis &&Other) = default;94 95 // Returns the instruction at the provided address. Returns nullptr if there96 // is no instruction at the provided address.97 const Instr *getInstruction(uint64_t Address) const;98 99 // Returns the instruction at the provided adress, dying if the instruction is100 // not found.101 const Instr &getInstructionOrDie(uint64_t Address) const;102 103 // Returns a pointer to the previous/next instruction in sequence,104 // respectively. Returns nullptr if the next/prev instruction doesn't exist,105 // or if the provided instruction doesn't exist.106 const Instr *getPrevInstructionSequential(const Instr &InstrMeta) const;107 const Instr *getNextInstructionSequential(const Instr &InstrMeta) const;108 109 // Returns whether this instruction is used by CFI to trap the program.110 bool isCFITrap(const Instr &InstrMeta) const;111 112 // Returns whether this instruction is a call to a function that will trap on113 // CFI violations (i.e., it serves as a trap in this instance).114 bool willTrapOnCFIViolation(const Instr &InstrMeta) const;115 116 // Returns whether this function can fall through to the next instruction.117 // Undefined (and bad) instructions cannot fall through, and instruction that118 // modify the control flow can only fall through if they are conditional119 // branches or calls.120 bool canFallThrough(const Instr &InstrMeta) const;121 122 // Returns the definitive next instruction. This is different from the next123 // instruction sequentially as it will follow unconditional branches (assuming124 // they can be resolved at compile time, i.e. not indirect). This method125 // returns nullptr if the provided instruction does not transfer control flow126 // to exactly one instruction that is known deterministically at compile time.127 // Also returns nullptr if the deterministic target does not exist in this128 // file.129 const Instr *getDefiniteNextInstruction(const Instr &InstrMeta) const;130 131 // Get a list of deterministic control flows that lead to the provided132 // instruction. This list includes all static control flow cross-references as133 // well as the previous instruction if it can fall through.134 std::set<const Instr *>135 getDirectControlFlowXRefs(const Instr &InstrMeta) const;136 137 // Returns whether this instruction uses a register operand.138 bool usesRegisterOperand(const Instr &InstrMeta) const;139 140 // Returns the list of indirect instructions.141 const std::set<object::SectionedAddress> &getIndirectInstructions() const;142 143 const MCRegisterInfo *getRegisterInfo() const;144 const MCInstrInfo *getMCInstrInfo() const;145 const MCInstrAnalysis *getMCInstrAnalysis() const;146 147 // Returns the inlining information for the provided address.148 Expected<DIInliningInfo>149 symbolizeInlinedCode(object::SectionedAddress Address);150 151 // Returns whether the provided Graph represents a protected indirect control152 // flow instruction in this file.153 CFIProtectionStatus validateCFIProtection(const GraphResult &Graph) const;154 155 // Returns the first place the operand register is clobbered between the CFI-156 // check and the indirect CF instruction execution. We do this by walking157 // backwards from the indirect CF and ensuring there is at most one load158 // involving the operand register (which is the indirect CF itself on x86).159 // If the register is not modified, returns the address of the indirect CF160 // instruction. The result is undefined if the provided graph does not fall161 // under either the FAIL_REGISTER_CLOBBERED or PROTECTED status (see162 // CFIProtectionStatus).163 uint64_t indirectCFOperandClobber(const GraphResult& Graph) const;164 165 // Prints an instruction to the provided stream using this object's pretty-166 // printers.167 void printInstruction(const Instr &InstrMeta, raw_ostream &OS) const;168 169protected:170 // Construct a blank object with the provided triple and features. Used in171 // testing, where a sub class will dependency inject protected methods to172 // allow analysis of raw binary, without requiring a fully valid ELF file.173 FileAnalysis(const Triple &ObjectTriple, const SubtargetFeatures &Features);174 175 // Add an instruction to this object.176 void addInstruction(const Instr &Instruction);177 178 // Disassemble and parse the provided bytes into this object. Instruction179 // address calculation is done relative to the provided SectionAddress.180 void parseSectionContents(ArrayRef<uint8_t> SectionBytes,181 object::SectionedAddress Address);182 183 // Constructs and initialises members required for disassembly.184 Error initialiseDisassemblyMembers();185 186 // Parses code sections from the internal object file. Saves them into the187 // internal members. Should only be called once by Create().188 Error parseCodeSections();189 190 // Parses the symbol table to look for the addresses of functions that will191 // trap on CFI violations.192 Error parseSymbolTable();193 194private:195 // Members that describe the input file.196 object::OwningBinary<object::Binary> Binary;197 const object::ObjectFile *Object = nullptr;198 Triple ObjectTriple;199 std::string ArchName;200 std::string MCPU;201 const Target *ObjectTarget = nullptr;202 SubtargetFeatures Features;203 204 // Members required for disassembly.205 std::unique_ptr<const MCRegisterInfo> RegisterInfo;206 std::unique_ptr<const MCAsmInfo> AsmInfo;207 std::unique_ptr<MCSubtargetInfo> SubtargetInfo;208 std::unique_ptr<const MCInstrInfo> MII;209 std::unique_ptr<MCContext> Context;210 std::unique_ptr<const MCDisassembler> Disassembler;211 std::unique_ptr<const MCInstrAnalysis> MIA;212 std::unique_ptr<MCInstPrinter> Printer;213 214 // Symbolizer used for debug information parsing.215 std::unique_ptr<symbolize::LLVMSymbolizer> Symbolizer;216 217 // A mapping between the virtual memory address to the instruction metadata218 // struct. TODO(hctim): Reimplement this as a sorted vector to avoid per-219 // insertion allocation.220 std::map<uint64_t, Instr> Instructions;221 222 // Contains a mapping between a specific address, and a list of instructions223 // that use this address as a branch target (including call instructions).224 DenseMap<uint64_t, std::vector<uint64_t>> StaticBranchTargetings;225 226 // A list of addresses of indirect control flow instructions.227 std::set<object::SectionedAddress> IndirectInstructions;228 229 // The addresses of functions that will trap on CFI violations.230 SmallSet<uint64_t, 4> TrapOnFailFunctionAddresses;231};232 233class UnsupportedDisassembly : public ErrorInfo<UnsupportedDisassembly> {234public:235 static char ID;236 std::string Text;237 238 UnsupportedDisassembly(StringRef Text);239 240 void log(raw_ostream &OS) const override;241 std::error_code convertToErrorCode() const override;242};243 244} // namespace cfi_verify245} // namespace llvm246 247#endif // LLVM_CFI_VERIFY_FILE_ANALYSIS_H248