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chromium / chromium / src / 75f4152e5cde392fdb1519fdebc34faed74e3e12 / . / courgette / disassembler_elf_32.h
blob: a75773d78b0579f7dc64b58f1ed05c34fab17126 [file] [log] [blame]
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]1// Copyright 2013 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef COURGETTE_DISASSEMBLER_ELF_32_H_
6#define COURGETTE_DISASSEMBLER_ELF_32_H_
7
aviab98dcc92015-12-21 19:35:33[diff] [blame]8#include <stddef.h>
9#include <stdint.h>
10
etiennep7d4e8ee2016-05-11 20:13:36[diff] [blame]11#include <memory>
huangsc8037632016-05-19 18:16:40[diff] [blame]12#include <string>
huangsdda11d062016-03-14 16:35:39[diff] [blame]13#include <vector>
14
aviab98dcc92015-12-21 19:35:33[diff] [blame]15#include "base/macros.h"
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]16#include "courgette/disassembler.h"
huangsdda11d062016-03-14 16:35:39[diff] [blame]17#include "courgette/image_utils.h"
huangs257f9fb2017-03-23 23:17:50[diff] [blame]18#include "courgette/instruction_utils.h"
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]19#include "courgette/memory_allocator.h"
20#include "courgette/types_elf.h"
21
22namespace courgette {
23
24class AssemblyProgram;
25
huangsdda11d062016-03-14 16:35:39[diff] [blame]26// A Courgette disassembler for 32-bit ELF files. This is only a partial
27// implementation that admits subclasses for the architecture-specific parts of
28// 32-bit ELF file processing. Specifically:
29// - RelToRVA() processes entries in ELF relocation table.
30// - ParseRelocationSection() verifies the organization of the ELF relocation
31// table.
32// - ParseRel32RelocsFromSection() finds branch targets by looking for relative
33// branch/call opcodes in the particular architecture's machine code.
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]34class DisassemblerElf32 : public Disassembler {
35 public:
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]36 // Different instructions encode the target rva differently. This
37 // class encapsulates this behavior. public for use in unit tests.
38 class TypedRVA {
39 public:
huangsdda11d062016-03-14 16:35:39[diff] [blame]40 explicit TypedRVA(RVA rva) : rva_(rva) { }
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]41
huangsdda11d062016-03-14 16:35:39[diff] [blame]42 virtual ~TypedRVA() { }
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]43
huangsdda11d062016-03-14 16:35:39[diff] [blame]44 RVA rva() const { return rva_; }
45 RVA relative_target() const { return relative_target_; }
46 FileOffset file_offset() const { return file_offset_; }
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]47
48 void set_relative_target(RVA relative_target) {
49 relative_target_ = relative_target;
50 }
etiennep7d4e8ee2016-05-11 20:13:36[diff] [blame]51 void set_file_offset(FileOffset file_offset) { file_offset_ = file_offset; }
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]52
paulgazz@chromium.org2b637b62013-08-01 00:11:24[diff] [blame]53 // Computes the relative jump's offset from the op in p.
aviab98dcc92015-12-21 19:35:33[diff] [blame]54 virtual CheckBool ComputeRelativeTarget(const uint8_t* op_pointer) = 0;
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]55
huangsc8037632016-05-19 18:16:40[diff] [blame]56 // Emits the assembly instruction corresponding to |label|.
huangs7b221a52016-11-09 22:28:23[diff] [blame]57 virtual CheckBool EmitInstruction(Label* label,
58 InstructionReceptor* receptor) = 0;
paulgazz@chromium.org2b637b62013-08-01 00:11:24[diff] [blame]59
huangsdda11d062016-03-14 16:35:39[diff] [blame]60 // Returns the size of the instruction containing the RVA.
aviab98dcc92015-12-21 19:35:33[diff] [blame]61 virtual uint16_t op_size() const = 0;
paulgazz@chromium.org2b637b62013-08-01 00:11:24[diff] [blame]62
huangsdda11d062016-03-14 16:35:39[diff] [blame]63 // Comparator for sorting, which assumes uniqueness of RVAs.
etiennep7d4e8ee2016-05-11 20:13:36[diff] [blame]64 static bool IsLessThanByRVA(const std::unique_ptr<TypedRVA>& a,
65 const std::unique_ptr<TypedRVA>& b) {
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]66 return a->rva() < b->rva();
huangs3da0dd932016-04-28 22:14:45[diff] [blame]67 }
68
69 // Comparator for sorting, which assumes uniqueness of file offsets.
etiennep7d4e8ee2016-05-11 20:13:36[diff] [blame]70 static bool IsLessThanByFileOffset(const std::unique_ptr<TypedRVA>& a,
71 const std::unique_ptr<TypedRVA>& b) {
huangs3da0dd932016-04-28 22:14:45[diff] [blame]72 return a->file_offset() < b->file_offset();
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]73 }
74
huangs7b221a52016-11-09 22:28:23[diff] [blame]75 private:
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]76 const RVA rva_;
huangsdda11d062016-03-14 16:35:39[diff] [blame]77 RVA relative_target_ = kNoRVA;
78 FileOffset file_offset_ = kNoFileOffset;
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]79 };
80
huangsc8037632016-05-19 18:16:40[diff] [blame]81 // Visitor/adaptor to translate RVA to target RVA. This is the ELF
82 // counterpart to RvaVisitor_Rel32 that uses TypedRVA.
83 class Elf32RvaVisitor_Rel32 :
84 public VectorRvaVisitor<std::unique_ptr<TypedRVA>> {
85 public:
86 Elf32RvaVisitor_Rel32(
87 const std::vector<std::unique_ptr<TypedRVA>>& rva_locations);
88 ~Elf32RvaVisitor_Rel32() override { }
89
90 // VectorRvaVisitor<TypedRVA*> interfaces.
91 RVA Get() const override;
92
93 private:
94 DISALLOW_COPY_AND_ASSIGN(Elf32RvaVisitor_Rel32);
95 };
96
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]97 public:
etiennep5059bca2016-07-08 17:55:20[diff] [blame]98 DisassemblerElf32(const uint8_t* start, size_t length);
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]99
huangsdda11d062016-03-14 16:35:39[diff] [blame]100 ~DisassemblerElf32() override { }
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]101
huangsdda11d062016-03-14 16:35:39[diff] [blame]102 // Disassembler interfaces.
103 RVA FileOffsetToRVA(FileOffset file_offset) const override;
104 FileOffset RVAToFileOffset(RVA rva) const override;
huangsf940a8c92016-03-23 20:40:35[diff] [blame]105 RVA PointerToTargetRVA(const uint8_t* p) const override;
huangs7b221a52016-11-09 22:28:23[diff] [blame]106 ExecutableType kind() const override = 0;
huangs85636222017-01-13 18:09:13[diff] [blame]107 uint64_t image_base() const override { return 0; }
huangsdda11d062016-03-14 16:35:39[diff] [blame]108 bool ParseHeader() override;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]109
huangsdda11d062016-03-14 16:35:39[diff] [blame]110 virtual e_machine_values ElfEM() const = 0;
huangsc8037632016-05-19 18:16:40[diff] [blame]111
112 CheckBool IsValidTargetRVA(RVA rva) const WARN_UNUSED_RESULT;
113
114 // Converts an ELF relocation instruction into an RVA.
115 virtual CheckBool RelToRVA(Elf32_Rel rel, RVA* result)
116 const WARN_UNUSED_RESULT = 0;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]117
118 // Public for unittests only
etiennep7d4e8ee2016-05-11 20:13:36[diff] [blame]119 std::vector<RVA>& Abs32Locations() { return abs32_locations_; }
120 std::vector<std::unique_ptr<TypedRVA>>& Rel32Locations() {
121 return rel32_locations_;
122 }
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]123
124 protected:
etiennep5059bca2016-07-08 17:55:20[diff] [blame]125 // Returns 'true' if an valid executable is detected using only quick checks.
126 // Derived classes should inject |elf_em| corresponding to their architecture,
127 // which will be checked against the detected one.
128 static bool QuickDetect(const uint8_t* start,
129 size_t length,
130 e_machine_values elf_em);
131
halyavinc9de6f72015-03-24 15:40:12[diff] [blame]132 bool UpdateLength();
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]133
134 // Misc Section Helpers
135
sorin@chromium.orge3e696d32013-06-21 20:41:36[diff] [blame]136 Elf32_Half SectionHeaderCount() const {
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]137 return section_header_table_size_;
138 }
139
huangsdda11d062016-03-14 16:35:39[diff] [blame]140 const Elf32_Shdr* SectionHeader(Elf32_Half id) const {
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]141 assert(id >= 0 && id < SectionHeaderCount());
huangs8cffb282016-04-09 19:43:50[diff] [blame]142 return &section_header_table_[id];
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]143 }
144
huangsdda11d062016-03-14 16:35:39[diff] [blame]145 const uint8_t* SectionBody(Elf32_Half id) const {
huangs16f01e02016-04-21 19:38:38[diff] [blame]146 // TODO(huangs): Assert that section does not have SHT_NOBITS.
huangsdda11d062016-03-14 16:35:39[diff] [blame]147 return FileOffsetToPointer(SectionHeader(id)->sh_offset);
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]148 }
huangs16f01e02016-04-21 19:38:38[diff] [blame]149
150 // Gets the |name| of section |shdr|. Returns true on success.
151 CheckBool SectionName(const Elf32_Shdr& shdr, std::string* name) const;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]152
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]153 // Misc Segment Helpers
154
sorin@chromium.orge3e696d32013-06-21 20:41:36[diff] [blame]155 Elf32_Half ProgramSegmentHeaderCount() const {
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]156 return program_header_table_size_;
157 }
158
huangsdda11d062016-03-14 16:35:39[diff] [blame]159 const Elf32_Phdr* ProgramSegmentHeader(Elf32_Half id) const {
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]160 assert(id >= 0 && id < ProgramSegmentHeaderCount());
161 return program_header_table_ + id;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]162 }
163
164 // Misc address space helpers
165
huangsdda11d062016-03-14 16:35:39[diff] [blame]166 CheckBool RVAsToFileOffsets(const std::vector<RVA>& rvas,
huangs7b221a52016-11-09 22:28:23[diff] [blame]167 std::vector<FileOffset>* file_offsets) const;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]168
etiennep7d4e8ee2016-05-11 20:13:36[diff] [blame]169 CheckBool RVAsToFileOffsets(
huangs7b221a52016-11-09 22:28:23[diff] [blame]170 std::vector<std::unique_ptr<TypedRVA>>* typed_rvas) const;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]171
huangs257f9fb2017-03-23 23:17:50[diff] [blame]172 // Helpers for ParseFile().
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]173
huangsdda11d062016-03-14 16:35:39[diff] [blame]174 virtual CheckBool ParseRelocationSection(const Elf32_Shdr* section_header,
huangs7b221a52016-11-09 22:28:23[diff] [blame]175 InstructionReceptor* receptor) const
huangsdda11d062016-03-14 16:35:39[diff] [blame]176 WARN_UNUSED_RESULT = 0;
paulgazz@chromium.org144c8e92013-07-23 21:18:19[diff] [blame]177
huangsdda11d062016-03-14 16:35:39[diff] [blame]178 virtual CheckBool ParseRel32RelocsFromSection(const Elf32_Shdr* section)
179 WARN_UNUSED_RESULT = 0;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]180
huangsdc779d92017-03-01 22:22:38[diff] [blame]181 CheckBool ParseAbs32Relocs() WARN_UNUSED_RESULT;
182
183 // Extracts all rel32 TypedRVAs. Does not sort the result.
184 CheckBool ParseRel32RelocsFromSections() WARN_UNUSED_RESULT;
185
huangsc8037632016-05-19 18:16:40[diff] [blame]186 // Disassembler interfaces.
huangs257f9fb2017-03-23 23:17:50[diff] [blame]187 bool ExtractAbs32Locations() override;
188 bool ExtractRel32Locations() override;
huangsc8037632016-05-19 18:16:40[diff] [blame]189 RvaVisitor* CreateAbs32TargetRvaVisitor() override;
190 RvaVisitor* CreateRel32TargetRvaVisitor() override;
191 void RemoveUnusedRel32Locations(AssemblyProgram* program) override;
huangs257f9fb2017-03-23 23:17:50[diff] [blame]192 InstructionGenerator GetInstructionGenerator(
193 AssemblyProgram* program) override;
huangsc8037632016-05-19 18:16:40[diff] [blame]194
huangs7b221a52016-11-09 22:28:23[diff] [blame]195 CheckBool ParseFile(AssemblyProgram* target,
196 InstructionReceptor* receptor) const WARN_UNUSED_RESULT;
huangsdda11d062016-03-14 16:35:39[diff] [blame]197
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]198 CheckBool ParseProgbitsSection(
huangsdda11d062016-03-14 16:35:39[diff] [blame]199 const Elf32_Shdr* section_header,
200 std::vector<FileOffset>::iterator* current_abs_offset,
201 std::vector<FileOffset>::iterator end_abs_offset,
etiennep7d4e8ee2016-05-11 20:13:36[diff] [blame]202 std::vector<std::unique_ptr<TypedRVA>>::iterator* current_rel,
203 std::vector<std::unique_ptr<TypedRVA>>::iterator end_rel,
huangs7b221a52016-11-09 22:28:23[diff] [blame]204 AssemblyProgram* program,
205 InstructionReceptor* receptor) const WARN_UNUSED_RESULT;
huangsdda11d062016-03-14 16:35:39[diff] [blame]206
207 CheckBool ParseSimpleRegion(FileOffset start_file_offset,
208 FileOffset end_file_offset,
huangs7b221a52016-11-09 22:28:23[diff] [blame]209 InstructionReceptor* receptor) const
210 WARN_UNUSED_RESULT;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]211
huangsdda11d062016-03-14 16:35:39[diff] [blame]212 CheckBool CheckSection(RVA rva) WARN_UNUSED_RESULT;
huangsdda11d062016-03-14 16:35:39[diff] [blame]213
214 const Elf32_Ehdr* header_;
huangs691893002016-04-19 20:04:33[diff] [blame]215
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]216 Elf32_Half section_header_table_size_;
huangs691893002016-04-19 20:04:33[diff] [blame]217
218 // Section header table, ordered by section id.
219 std::vector<Elf32_Shdr> section_header_table_;
220
221 // An ordering of |section_header_table_|, sorted by file offset.
222 std::vector<Elf32_Half> section_header_file_offset_order_;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]223
huangsdda11d062016-03-14 16:35:39[diff] [blame]224 const Elf32_Phdr* program_header_table_;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]225 Elf32_Half program_header_table_size_;
226
huangs16f01e02016-04-21 19:38:38[diff] [blame]227 // Pointer to string table containing section names.
huangsdda11d062016-03-14 16:35:39[diff] [blame]228 const char* default_string_section_;
huangs16f01e02016-04-21 19:38:38[diff] [blame]229 size_t default_string_section_size_;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]230
huangs257f9fb2017-03-23 23:17:50[diff] [blame]231 // Sorted abs32 RVAs.
232 std::vector<RVA> abs32_locations_;
233 // Sorted rel32 RVAs. This is mutable because ParseFile() temporarily sorts
234 // these by file offsets.
huangs7b221a52016-11-09 22:28:23[diff] [blame]235 mutable std::vector<std::unique_ptr<TypedRVA>> rel32_locations_;
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]236
huangs7b221a52016-11-09 22:28:23[diff] [blame]237 private:
paulgazz@chromium.org39ed9732013-06-20 10:17:53[diff] [blame]238 DISALLOW_COPY_AND_ASSIGN(DisassemblerElf32);
239};
240
241} // namespace courgette
242
243#endif // COURGETTE_DISASSEMBLER_ELF_32_H_