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// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/zucchini/reloc_elf.h"
#include <stdint.h>
#include <algorithm>
#include <memory>
#include <utility>
#include <vector>
#include "base/numerics/safe_conversions.h"
#include "components/zucchini/address_translator.h"
#include "components/zucchini/algorithm.h"
#include "components/zucchini/disassembler_elf.h"
#include "components/zucchini/image_utils.h"
#include "components/zucchini/test_utils.h"
#include "components/zucchini/type_elf.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace zucchini {
namespace {
template <class Elf_Shdr>
SectionDimensionsElf MakeSectionDimensions(const BufferRegion& region,
offset_t entry_size) {
using sh_offset_t = decltype(Elf_Shdr::sh_offset);
using sh_size_t = decltype(Elf_Shdr::sh_size);
using sh_entsize_t = decltype(Elf_Shdr::sh_entsize);
return SectionDimensionsElf{Elf_Shdr{
0, // sh_name
0, // sh_type
0, // sh_flags
0, // sh_addr
// sh_offset
base::checked_cast<sh_offset_t>(region.offset),
// sh_size
base::checked_cast<sh_size_t>(region.size),
0, // sh_link
0, // sh_info
0, // sh_addralign
// sh_entsize
base::checked_cast<sh_entsize_t>(entry_size),
}};
}
// Helper to manipulate an image with one or more relocation tables.
template <class ELF_INTEL_TRAITS>
class FakeImageWithReloc {
public:
using ElfIntelTraits = ELF_INTEL_TRAITS;
struct RelocSpec {
offset_t start;
std::vector<uint8_t> data;
};
FakeImageWithReloc(size_t image_size,
rva_t base_rva,
const std::vector<RelocSpec>& reloc_specs)
: image_data_(image_size, 0xFF),
mutable_image_(&image_data_[0], image_data_.size()) {
translator_.Initialize({{0, static_cast<offset_t>(image_size), base_rva,
static_cast<rva_t>(image_size)}});
// Set up test image with reloc sections.
for (const RelocSpec& reloc_spec : reloc_specs) {
BufferRegion reloc_region = {reloc_spec.start, reloc_spec.data.size()};
std::ranges::copy(reloc_spec.data,
image_data_.begin() + reloc_region.lo());
section_dimensions_.emplace_back(
MakeSectionDimensions<typename ElfIntelTraits::Elf_Shdr>(
reloc_region, ElfIntelTraits::kVAWidth));
reloc_regions_.push_back(reloc_region);
}
}
std::vector<Reference> ExtractRelocReferences() {
const size_t image_size = image_data_.size();
ConstBufferView image = {image_data_.data(), image_size};
// Make RelocReaderElf.
auto reader = std::make_unique<RelocReaderElf>(
image, ElfIntelTraits::kBitness, section_dimensions_,
ElfIntelTraits::kRelType, 0, image_size, translator_);
// Read all references and check.
std::vector<Reference> refs;
for (std::optional<Reference> ref = reader->GetNext(); ref.has_value();
ref = reader->GetNext()) {
refs.push_back(ref.value());
}
return refs;
}
std::unique_ptr<RelocWriterElf> MakeRelocWriter() {
return std::move(std::make_unique<RelocWriterElf>(
mutable_image_, ElfIntelTraits::kBitness, translator_));
}
std::vector<uint8_t> GetRawRelocData(int reloc_index) {
BufferRegion reloc_region = reloc_regions_[reloc_index];
return Sub(image_data_, reloc_region.lo(), reloc_region.hi());
}
private:
std::vector<uint8_t> image_data_;
MutableBufferView mutable_image_;
std::vector<BufferRegion> reloc_regions_;
std::vector<SectionDimensionsElf> section_dimensions_;
AddressTranslator translator_;
};
} // namespace
TEST(RelocElfTest, ReadWrite32) {
// Set up mock image: Size = 0x3000, .reloc at 0x600. RVA is 0x40000 + offset.
constexpr size_t kImageSize = 0x3000;
constexpr rva_t kBaseRva = 0x40000;
constexpr offset_t kRelocStart0 = 0x600;
// "C0 10 04 00 08 00 00 00" represents
// (r_sym, r_type, r_offset) = (0x000000, 0x08, 0x000410C0).
// r_type = 0x08 = R_386_RELATIVE, and so |r_offset| is an RVA 0x000410C0.
// Zucchini does not care about |r_sym|.
std::vector<uint8_t> reloc_data0 = ParseHexString(
"C0 10 04 00 08 00 00 00 " // R_386_RELATIVE.
"F8 10 04 00 08 AB CD EF " // R_386_RELATIVE.
"00 10 04 00 00 AB CD EF " // R_386_NONE.
"00 10 04 00 07 AB CD EF"); // R_386_JMP_SLOT.
constexpr offset_t kRelocStart1 = 0x620;
std::vector<uint8_t> reloc_data1 = ParseHexString(
"BC 20 04 00 08 00 00 00 " // R_386_RELATIVE.
"A0 20 04 00 08 AB CD EF"); // R_386_RELATIVE.
FakeImageWithReloc<Elf32IntelTraits> fake_image(
kImageSize, kBaseRva,
{{kRelocStart0, reloc_data0}, {kRelocStart1, reloc_data1}});
// Only R_386_RELATIVE references are extracted. Targets are translated from
// address (e.g., 0x000420BC) to offset (e.g., 0x20BC).
std::vector<Reference> exp_refs{
{0x600, 0x10C0}, {0x608, 0x10F8}, {0x620, 0x20BC}, {0x628, 0x20A0}};
EXPECT_EQ(exp_refs, fake_image.ExtractRelocReferences());
// Write reference, extract bytes and check.
std::unique_ptr<RelocWriterElf> writer = fake_image.MakeRelocWriter();
writer->PutNext({0x608, 0x1F83});
std::vector<uint8_t> exp_reloc_data0 = ParseHexString(
"C0 10 04 00 08 00 00 00 " // R_386_RELATIVE.
"83 1F 04 00 08 AB CD EF " // R_386_RELATIVE (address modified).
"00 10 04 00 00 AB CD EF " // R_386_NONE.
"00 10 04 00 07 AB CD EF"); // R_386_JMP_SLOT.
EXPECT_EQ(exp_reloc_data0, fake_image.GetRawRelocData(0));
writer->PutNext({0x628, 0x2950});
std::vector<uint8_t> exp_reloc_data1 = ParseHexString(
"BC 20 04 00 08 00 00 00 " // R_386_RELATIVE.
"50 29 04 00 08 AB CD EF"); // R_386_RELATIVE (address modified).
EXPECT_EQ(exp_reloc_data1, fake_image.GetRawRelocData(1));
}
TEST(RelocElfTest, Limit32) {
constexpr size_t kImageSize = 0x3000;
constexpr offset_t kBaseRva = 0x40000;
constexpr offset_t kRelocStart = 0x600;
// All R_386_RELATIVE.
std::vector<uint8_t> reloc_data = ParseHexString(
// Strictly within file.
"00 00 04 00 08 00 00 00 "
"00 10 04 00 08 00 00 00 "
"F0 2F 04 00 08 00 00 00 "
"F8 2F 04 00 08 00 00 00 "
"FC 2F 04 00 08 00 00 00 "
// Straddles end of file.
"FD 2F 04 00 08 00 00 00 "
"FE 2F 04 00 08 00 00 00 "
"FF 2F 04 00 08 00 00 00 "
// Beyond end of file.
"00 30 04 00 08 00 00 00 "
"01 30 04 00 08 00 00 00 "
"FC FF FF 7F 08 00 00 00 "
"FE FF FF 7F 08 00 00 00 "
"00 00 00 80 08 00 00 00 "
"FC FF FF FF 08 00 00 00 "
"FF FF FF FF 08 00 00 00 "
// Another good reference.
"34 12 04 00 08 00 00 00");
FakeImageWithReloc<Elf32IntelTraits> fake_image(kImageSize, kBaseRva,
{{kRelocStart, reloc_data}});
std::vector<Reference> exp_refs{{0x600, 0x0000}, {0x608, 0x1000},
{0x610, 0x2FF0}, {0x618, 0x2FF8},
{0x620, 0x2FFC}, {0x678, 0x1234}};
EXPECT_EQ(exp_refs, fake_image.ExtractRelocReferences());
}
TEST(RelocElfTest, Limit64) {
constexpr size_t kImageSize = 0x3000;
constexpr offset_t kBaseRva = 0x40000;
constexpr offset_t kRelocStart = 0x600;
// All R_X86_64_RELATIVE.
std::vector<uint8_t> reloc_data = ParseHexString(
// Strictly within file.
"00 00 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
"00 10 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
"F0 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
"F4 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
"F8 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
// Straddles end of file.
"F9 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
"FC 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
"FF 2F 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
// Beyond end of file.
"00 30 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
"01 30 04 00 00 00 00 00 08 00 00 00 00 00 00 00 "
"FC FF FF 7F 00 00 00 00 08 00 00 00 00 00 00 00 "
"FE FF FF 7F 00 00 00 00 08 00 00 00 00 00 00 00 "
"00 00 00 80 00 00 00 00 08 00 00 00 00 00 00 00 "
"FC FF FF FF 00 00 00 00 08 00 00 00 00 00 00 00 "
"FF FF FF FF 00 00 00 00 08 00 00 00 00 00 00 00 "
"00 00 04 00 01 00 00 00 08 00 00 00 00 00 00 00 "
"FF FF FF FF FF FF FF FF 08 00 00 00 00 00 00 00 "
"F8 FF FF FF FF FF FF FF 08 00 00 00 00 00 00 00 "
// Another good reference.
"34 12 04 00 00 00 00 00 08 00 00 00 00 00 00 00");
FakeImageWithReloc<Elf64IntelTraits> fake_image(kImageSize, kBaseRva,
{{kRelocStart, reloc_data}});
std::vector<Reference> exp_refs{{0x600, 0x0000}, {0x610, 0x1000},
{0x620, 0x2FF0}, {0x630, 0x2FF4},
{0x640, 0x2FF8}, {0x720, 0x1234}};
EXPECT_EQ(exp_refs, fake_image.ExtractRelocReferences());
}
} // namespace zucchini
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