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Add symbol table search scaffolding and ELF32 implementation

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This commit is contained in:
Katy Coe
2019-10-21 00:00:05 +02:00
parent 491735044c
commit bebfba4f46
4 changed files with 115 additions and 4 deletions
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4
Il2CppInspector/FileFormatReader.cs
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@@ -20,6 +20,7 @@ namespace Il2CppInspector
long Position { get; set; }
string Arch { get; }
uint GlobalOffset { get; }
Dictionary<string, uint> GetSymbolTable();
uint[] GetFunctionTable();
U ReadMappedObject<U>(uint uiAddr) where U : new();
U[] ReadMappedArray<U>(uint uiAddr, int count) where U : new();
@@ -76,6 +77,9 @@ namespace Il2CppInspector
}
}
// Find search locations in the symbol table for Il2Cpp data
public virtual Dictionary<string, uint> GetSymbolTable() => null;
// Find search locations in the machine code for Il2Cpp data
public virtual uint[] GetFunctionTable() => throw new NotImplementedException();

62
Il2CppInspector/FileFormatReaders/ElfReader.cs
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@@ -1,19 +1,23 @@
/*
Copyright 2017 Perfare - https://github.com/Perfare/Il2CppDumper
Copyright 2017 Katy Coe - http://www.hearthcode.org - http://www.djkaty.com
Copyright 2017-2019 Katy Coe - http://www.hearthcode.org - http://www.djkaty.com
All rights reserved.
*/
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net.Sockets;
namespace Il2CppInspector
{
internal class ElfReader : FileFormatReader<ElfReader>
{
private program_header_table[] program_table_element;
private elf_32_shdr[] section_header_table;
private elf_header elf_header;
public ElfReader(Stream stream) : base(stream) { }
@@ -44,9 +48,65 @@ namespace Il2CppInspector
return false;
}
program_table_element = ReadArray<program_header_table>(elf_header.e_phoff, elf_header.e_phnum);
section_header_table = ReadArray<elf_32_shdr>(elf_header.e_shoff, elf_header.e_shnum);
return true;
}
public override Dictionary<string, uint> GetSymbolTable() {
// Three possible symbol tables in ELF files
var pTables = new List<(uint offset, uint count, uint strings)>();
// String table (a sequence of null-terminated strings, total length in sh_size
var SHT_STRTAB = section_header_table.FirstOrDefault(x => x.sh_type == 3u); // SHT_STRTAB = 3
if (SHT_STRTAB != null) {
// Section header shared object symbol table (.symtab)
if (section_header_table.FirstOrDefault(x => x.sh_type == 2u) is elf_32_shdr SHT_SYMTAB) // SHT_SYMTAB = 2
pTables.Add((SHT_SYMTAB.sh_offset, SHT_SYMTAB.sh_size / SHT_SYMTAB.sh_entsize, SHT_STRTAB.sh_offset));
// Section header executable symbol table (.dynsym)
if (section_header_table.FirstOrDefault(x => x.sh_type == 11u) is elf_32_shdr SHT_DYNSYM) // SHT_DYNSUM = 11
pTables.Add((SHT_DYNSYM.sh_offset, SHT_DYNSYM.sh_size / SHT_DYNSYM.sh_entsize, SHT_STRTAB.sh_offset));
}
// Symbol table in dynamic section (DT_SYMTAB)
// Normally the same as .dynsym except that .dynsym may be removed in stripped binaries
if (program_table_element.FirstOrDefault(x => x.p_type == 2u) is program_header_table PT_DYNAMIC) // PT_DYNAMIC = 2
{
// Get the dynamic table
var dynamic_table = ReadArray<elf_32_dynamic>(PT_DYNAMIC.p_offset, (int) PT_DYNAMIC.p_filesz / 8 /* sizeof(elf_32_dynamic) */);
// Dynamic string table
var DT_STRTAB = dynamic_table.FirstOrDefault(x => x.d_tag == 5u); // DT_STRTAB = 5
if (DT_STRTAB != null) {
if (dynamic_table.FirstOrDefault(x => x.d_tag == 6u) is elf_32_dynamic DT_SYMTAB) { // DT_SYMTAB = 6
// Find the next pointer in the dynamic table to calculate the length of the symbol table
var end = (from x in dynamic_table where x.d_un > DT_SYMTAB.d_un orderby x.d_un select x).First().d_un;
// Dynamic symbol table
pTables.Add((DT_SYMTAB.d_un, (end - DT_SYMTAB.d_un) / 16 /* sizeof(elf_32_sym) */, DT_STRTAB.d_un));
}
}
}
// Now iterate through all of the symbol and string tables we found to build a full list
var symbolTable = new Dictionary<string, uint>();
foreach (var pTab in pTables) {
var symbol_table = ReadArray<elf_32_sym>(pTab.offset, (int) pTab.count);
foreach (var symbol in symbol_table) {
var name = ReadNullTerminatedString(pTab.strings + symbol.st_name);
// Avoid duplicates
symbolTable.TryAdd(name, symbol.st_value);
}
}
return symbolTable;
}
public override uint[] GetFunctionTable() {
// Find dynamic section
var dynamic = new elf_32_shdr();

18
Il2CppInspector/FileFormatReaders/FormatLayouts/Elf.cs
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@@ -1,6 +1,6 @@
/*
Copyright 2017 Perfare - https://github.com/Perfare/Il2CppDumper
Copyright 2017 Katy Coe - http://www.hearthcode.org - http://www.djkaty.com
Copyright 2017-2019 Katy Coe - http://www.hearthcode.org - http://www.djkaty.com
All rights reserved.
*/
@@ -85,5 +85,21 @@ namespace Il2CppInspector
public uint sh_addralign;
public uint sh_entsize;
}
internal class elf_32_sym
{
public uint st_name;
public uint st_value;
public uint st_size;
public byte st_info;
public byte st_other;
public ushort st_shndx;
}
internal class elf_32_dynamic
{
public uint d_tag;
public uint d_un;
}
#pragma warning restore CS0649
}

35
Il2CppInspector/Il2CppBinary.cs
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@@ -7,6 +7,7 @@
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
namespace Il2CppInspector
@@ -50,19 +51,49 @@ namespace Il2CppInspector
public bool Initialize(double version, uint imageIndex = 0) {
var subImage = Image[imageIndex];
subImage.Stream.Version = version;
// Try searching the symbol table
var symbols = subImage.GetSymbolTable();
if (symbols?.Any() ?? false) {
Console.WriteLine($"Symbol table(s) found with {symbols.Count} entries");
symbols.TryGetValue("g_CodeRegistration", out var code);
symbols.TryGetValue("g_MetadataRegistration", out var metadata);
if (code != 0 && metadata != 0) {
Console.WriteLine("Required structures acquired from symbol lookup");
Configure(subImage, code, metadata);
return true;
}
else {
Console.WriteLine("No matches in symbol table");
}
}
else if (symbols != null) {
Console.WriteLine("No symbol table present in binary file");
}
else {
Console.WriteLine("Symbol table search not implemented for this binary format");
}
// Try searching the function table
var addrs = subImage.GetFunctionTable();
Console.WriteLine("Function Table:");
Console.WriteLine(string.Join(", ", from a in addrs select string.Format($"0x{a:X8}")));
Debug.WriteLine("Function table:");
Debug.WriteLine(string.Join(", ", from a in addrs select string.Format($"0x{a:X8}")));
foreach (var loc in addrs)
if (loc != 0) {
var (code, metadata) = ConsiderCode(loc, Image.GlobalOffset);
if (code != 0) {
Console.WriteLine("Required structures acquired from code heuristics");
Configure(subImage, code, metadata);
return true;
}
}
Console.WriteLine("No matches via code heuristics");
return false;
}