1 // Copyright 2018 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 #include "components/zucchini/reloc_elf.h"
6
7 #include <stdint.h>
8
9 #include <algorithm>
10 #include <memory>
11 #include <utility>
12 #include <vector>
13
14 #include "base/numerics/safe_conversions.h"
15 #include "components/zucchini/address_translator.h"
16 #include "components/zucchini/algorithm.h"
17 #include "components/zucchini/disassembler_elf.h"
18 #include "components/zucchini/image_utils.h"
19 #include "components/zucchini/test_utils.h"
20 #include "components/zucchini/type_elf.h"
21 #include "testing/gtest/include/gtest/gtest.h"
22
23 namespace zucchini {
24
25 namespace {
26
27 template <class Elf_Shdr>
MakeSectionDimensions(const BufferRegion & region,offset_t entry_size)28 SectionDimensionsElf MakeSectionDimensions(const BufferRegion& region,
29 offset_t entry_size) {
30 using sh_offset_t = decltype(Elf_Shdr::sh_offset);
31 using sh_size_t = decltype(Elf_Shdr::sh_size);
32 using sh_entsize_t = decltype(Elf_Shdr::sh_entsize);
33 return SectionDimensionsElf{Elf_Shdr{
34 0, // sh_name
35 0, // sh_type
36 0, // sh_flags
37 0, // sh_addr
38 // sh_offset
39 base::checked_cast<sh_offset_t>(region.offset),
40 // sh_size
41 base::checked_cast<sh_size_t>(region.size),
42 0, // sh_link
43 0, // sh_info
44 0, // sh_addralign
45 // sh_entsize
46 base::checked_cast<sh_entsize_t>(entry_size),
47 }};
48 }
49
50 // Helper to manipulate an image with one or more relocation tables.
51 template <class ELF_INTEL_TRAITS>
52 class FakeImageWithReloc {
53 public:
54 using ElfIntelTraits = ELF_INTEL_TRAITS;
55 struct RelocSpec {
56 offset_t start;
57 std::vector<uint8_t> data;
58 };
59
FakeImageWithReloc(size_t image_size,rva_t base_rva,const std::vector<RelocSpec> & reloc_specs)60 FakeImageWithReloc(size_t image_size,
61 rva_t base_rva,
62 const std::vector<RelocSpec>& reloc_specs)
63 : image_data_(image_size, 0xFF),
64 mutable_image_(&image_data_[0], image_data_.size()) {
65 translator_.Initialize({{0, static_cast<offset_t>(image_size), base_rva,
66 static_cast<rva_t>(image_size)}});
67 // Set up test image with reloc sections.
68 for (const RelocSpec& reloc_spec : reloc_specs) {
69 BufferRegion reloc_region = {reloc_spec.start, reloc_spec.data.size()};
70 std::copy(reloc_spec.data.begin(), reloc_spec.data.end(),
71 image_data_.begin() + reloc_region.lo());
72 section_dimensions_.emplace_back(
73 MakeSectionDimensions<typename ElfIntelTraits::Elf_Shdr>(
74 reloc_region, ElfIntelTraits::kVAWidth));
75 reloc_regions_.push_back(reloc_region);
76 }
77 }
78
ExtractRelocReferences()79 std::vector<Reference> ExtractRelocReferences() {
80 const size_t image_size = image_data_.size();
81 ConstBufferView image = {image_data_.data(), image_size};
82
83 // Make RelocReaderElf.
84 auto reader = std::make_unique<RelocReaderElf>(
85 image, ElfIntelTraits::kBitness, section_dimensions_,
86 ElfIntelTraits::kRelType, 0, image_size, translator_);
87
88 // Read all references and check.
89 std::vector<Reference> refs;
90 for (std::optional<Reference> ref = reader->GetNext(); ref.has_value();
91 ref = reader->GetNext()) {
92 refs.push_back(ref.value());
93 }
94 return refs;
95 }
96
MakeRelocWriter()97 std::unique_ptr<RelocWriterElf> MakeRelocWriter() {
98 return std::move(std::make_unique<RelocWriterElf>(
99 mutable_image_, ElfIntelTraits::kBitness, translator_));
100 }
101
GetRawRelocData(int reloc_index)102 std::vector<uint8_t> GetRawRelocData(int reloc_index) {
103 BufferRegion reloc_region = reloc_regions_[reloc_index];
104 return Sub(image_data_, reloc_region.lo(), reloc_region.hi());
105 }
106
107 private:
108 std::vector<uint8_t> image_data_;
109 MutableBufferView mutable_image_;
110 std::vector<BufferRegion> reloc_regions_;
111 std::vector<SectionDimensionsElf> section_dimensions_;
112 AddressTranslator translator_;
113 };
114
115 } // namespace
116
TEST(RelocElfTest,ReadWrite32)117 TEST(RelocElfTest, ReadWrite32) {
118 // Set up mock image: Size = 0x3000, .reloc at 0x600. RVA is 0x40000 + offset.
119 constexpr size_t kImageSize = 0x3000;
120 constexpr rva_t kBaseRva = 0x40000;
121
122 constexpr offset_t kRelocStart0 = 0x600;
123 // "C0 10 04 00 08 00 00 00" represents
124 // (r_sym, r_type, r_offset) = (0x000000, 0x08, 0x000410C0).
125 // r_type = 0x08 = R_386_RELATIVE, and so |r_offset| is an RVA 0x000410C0.
126 // Zucchini does not care about |r_sym|.
127 std::vector<uint8_t> reloc_data0 = ParseHexString(
128 "C0 10 04 00 08 00 00 00 " // R_386_RELATIVE.
129 "F8 10 04 00 08 AB CD EF " // R_386_RELATIVE.
130 "00 10 04 00 00 AB CD EF " // R_386_NONE.
131 "00 10 04 00 07 AB CD EF"); // R_386_JMP_SLOT.
132
133 constexpr offset_t kRelocStart1 = 0x620;
134 std::vector<uint8_t> reloc_data1 = ParseHexString(
135 "BC 20 04 00 08 00 00 00 " // R_386_RELATIVE.
136 "A0 20 04 00 08 AB CD EF"); // R_386_RELATIVE.
137
138 FakeImageWithReloc<Elf32IntelTraits> fake_image(
139 kImageSize, kBaseRva,
140 {{kRelocStart0, reloc_data0}, {kRelocStart1, reloc_data1}});
141
142 // Only R_386_RELATIVE references are extracted. Targets are translated from
143 // address (e.g., 0x000420BC) to offset (e.g., 0x20BC).
144 std::vector<Reference> exp_refs{
145 {0x600, 0x10C0}, {0x608, 0x10F8}, {0x620, 0x20BC}, {0x628, 0x20A0}};
146 EXPECT_EQ(exp_refs, fake_image.ExtractRelocReferences());
147
148 // Write reference, extract bytes and check.
149 std::unique_ptr<RelocWriterElf> writer = fake_image.MakeRelocWriter();
150
151 writer->PutNext({0x608, 0x1F83});
152 std::vector<uint8_t> exp_reloc_data0 = ParseHexString(
153 "C0 10 04 00 08 00 00 00 " // R_386_RELATIVE.
154 "83 1F 04 00 08 AB CD EF " // R_386_RELATIVE (address modified).
155 "00 10 04 00 00 AB CD EF " // R_386_NONE.
156 "00 10 04 00 07 AB CD EF"); // R_386_JMP_SLOT.
157 EXPECT_EQ(exp_reloc_data0, fake_image.GetRawRelocData(0));
158
159 writer->PutNext({0x628, 0x2950});
160 std::vector<uint8_t> exp_reloc_data1 = ParseHexString(
161 "BC 20 04 00 08 00 00 00 " // R_386_RELATIVE.
162 "50 29 04 00 08 AB CD EF"); // R_386_RELATIVE (address modified).
163 EXPECT_EQ(exp_reloc_data1, fake_image.GetRawRelocData(1));
164 }
165
TEST(RelocElfTest,Limit32)166 TEST(RelocElfTest, Limit32) {
167 constexpr size_t kImageSize = 0x3000;
168 constexpr offset_t kBaseRva = 0x40000;
169 constexpr offset_t kRelocStart = 0x600;
170 // All R_386_RELATIVE.
171 std::vector<uint8_t> reloc_data = ParseHexString(
172 // Strictly within file.
173 "00 00 04 00 08 00 00 00 "
174 "00 10 04 00 08 00 00 00 "
175 "F0 2F 04 00 08 00 00 00 "
176 "F8 2F 04 00 08 00 00 00 "
177 "FC 2F 04 00 08 00 00 00 "
178 // Straddles end of file.
179 "FD 2F 04 00 08 00 00 00 "
180 "FE 2F 04 00 08 00 00 00 "
181 "FF 2F 04 00 08 00 00 00 "
182 // Beyond end of file.
183 "00 30 04 00 08 00 00 00 "
184 "01 30 04 00 08 00 00 00 "
185 "FC FF FF 7F 08 00 00 00 "
186 "FE FF FF 7F 08 00 00 00 "
187 "00 00 00 80 08 00 00 00 "
188 "FC FF FF FF 08 00 00 00 "
189 "FF FF FF FF 08 00 00 00 "
190 // Another good reference.
191 "34 12 04 00 08 00 00 00");
192
193 FakeImageWithReloc<Elf32IntelTraits> fake_image(kImageSize, kBaseRva,
194 {{kRelocStart, reloc_data}});
195
196 std::vector<Reference> exp_refs{{0x600, 0x0000}, {0x608, 0x1000},
197 {0x610, 0x2FF0}, {0x618, 0x2FF8},
198 {0x620, 0x2FFC}, {0x678, 0x1234}};
199 EXPECT_EQ(exp_refs, fake_image.ExtractRelocReferences());
200 }
201
TEST(RelocElfTest,Limit64)202 TEST(RelocElfTest, Limit64) {
203 constexpr size_t kImageSize = 0x3000;
204 constexpr offset_t kBaseRva = 0x40000;
205
206 constexpr offset_t kRelocStart = 0x600;
207 // All R_X86_64_RELATIVE.
208 std::vector<uint8_t> reloc_data = ParseHexString(
209 // Strictly within file.
210 "00 00 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
211 "00 10 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
212 "F0 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
213 "F4 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
214 "F8 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
215 // Straddles end of file.
216 "F9 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
217 "FC 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
218 "FF 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
219 // Beyond end of file.
220 "00 30 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
221 "01 30 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
222 "FC FF FF 7F 00 00 00 00 08 00 00 00 00 00 00 00 "
223 "FE FF FF 7F 00 00 00 00 08 00 00 00 00 00 00 00 "
224 "00 00 00 80 00 00 00 00 08 00 00 00 00 00 00 00 "
225 "FC FF FF FF 00 00 00 00 08 00 00 00 00 00 00 00 "
226 "FF FF FF FF 00 00 00 00 08 00 00 00 00 00 00 00 "
227 "00 00 04 00 01 00 00 00 08 00 00 00 00 00 00 00 "
228 "FF FF FF FF FF FF FF FF 08 00 00 00 00 00 00 00 "
229 "F8 FF FF FF FF FF FF FF 08 00 00 00 00 00 00 00 "
230 // Another good reference.
231 "34 12 04 00 00 00 00 00 08 00 00 00 00 00 00 00");
232
233 FakeImageWithReloc<Elf64IntelTraits> fake_image(kImageSize, kBaseRva,
234 {{kRelocStart, reloc_data}});
235
236 std::vector<Reference> exp_refs{{0x600, 0x0000}, {0x610, 0x1000},
237 {0x620, 0x2FF0}, {0x630, 0x2FF4},
238 {0x640, 0x2FF8}, {0x720, 0x1234}};
239 EXPECT_EQ(exp_refs, fake_image.ExtractRelocReferences());
240 }
241
242 } // namespace zucchini
243