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IL2CPP: Add registration structs search via data heuristics

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This commit is contained in:
Katy Coe
2020-07-27 21:16:44 +02:00
parent a621e20b62
commit 2459bcb4a6
4 changed files with 242 additions and 49 deletions
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124
Il2CppInspector.Common/IL2CPP/Il2CppBinary.cs
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@@ -14,7 +14,7 @@ using System.Text.RegularExpressions;
namespace Il2CppInspector
{
public abstract class Il2CppBinary
public abstract partial class Il2CppBinary
{
public IFileFormatReader Image { get; }
@@ -85,32 +85,68 @@ namespace Il2CppInspector
protected Il2CppBinary(IFileFormatReader stream, uint codeRegistration, uint metadataRegistration) {
Image = stream;
Configure(Image, codeRegistration, metadataRegistration);
Configure(codeRegistration, metadataRegistration);
}
// Load and initialize a binary of any supported architecture
public static Il2CppBinary Load(IFileFormatReader stream, double metadataVersion) {
private static Il2CppBinary LoadImpl(IFileFormatReader stream) {
// Get type from image architecture
var type = Assembly.GetExecutingAssembly().GetType("Il2CppInspector.Il2CppBinary" + stream.Arch.ToUpper());
if (type == null)
throw new NotImplementedException("Unsupported architecture: " + stream.Arch);
var inst = (Il2CppBinary) Activator.CreateInstance(type, stream);
// Set width of long (convert to sizeof(int) for 32-bit files)
if (stream[0].Bits == 32) {
stream[0].Stream.PrimitiveMappings.Add(typeof(long), typeof(int));
stream[0].Stream.PrimitiveMappings.Add(typeof(ulong), typeof(uint));
}
return (Il2CppBinary) Activator.CreateInstance(type, stream[0]);
}
public static Il2CppBinary Load(IFileFormatReader stream, double metadataVersion) {
var inst = LoadImpl(stream);
// Try to process the IL2CPP image; return the instance if succeeded, otherwise null
return inst.Initialize(metadataVersion) ? inst : null;
return inst.InitializeWithoutMetadata(metadataVersion) ? inst : null;
}
// Supplying the Metadata class when loading a binary is optional
// If it is specified and both symbol table and function scanning fail,
// Metadata will be used to try to find the required structures with data analysis
// If it is not specified, data analysis will not be performed
public static Il2CppBinary Load(IFileFormatReader stream, Metadata metadata) {
var inst = LoadImpl(stream);
return inst.Initialize(metadata) ? inst : null;
}
// Architecture-specific search function
protected abstract (ulong, ulong) ConsiderCode(IFileFormatReader image, uint loc);
// Check all search locations
public bool Initialize(double version, uint imageIndex = 0) {
var subImage = Image[imageIndex];
subImage.Version = version;
// Try to find data structures via symbol table lookup, init function analysis and data heuristics
public bool Initialize(Metadata metadata) {
Image.Version = metadata.Version;
if (InitializeWithoutMetadata(metadata.Version))
return true;
// Resort to a full scan of the file
var (codePtr, metadataPtr) = ImageScan(metadata);
if (codePtr == 0) {
Console.WriteLine("No matches via data heuristics");
return false;
}
Console.WriteLine("Required structures acquired from data heuristics");
Configure(codePtr, metadataPtr);
return true;
}
// Try to find data structures via symbol table lookup and init function code analysis
public bool InitializeWithoutMetadata(double version) {
Image.Version = version;
// Try searching the symbol table
var symbols = subImage.GetSymbolTable();
var symbols = Image.GetSymbolTable();
if (symbols?.Any() ?? false) {
Console.WriteLine($"Symbol table(s) found with {symbols.Count} entries");
@@ -125,7 +161,7 @@ namespace Il2CppInspector
if (code != 0 && metadata != 0) {
Console.WriteLine("Required structures acquired from symbol lookup");
Configure(subImage, code, metadata);
Configure(code, metadata);
return true;
}
else {
@@ -140,17 +176,17 @@ namespace Il2CppInspector
}
// Try searching the function table
var addrs = subImage.GetFunctionTable();
var addrs = Image.GetFunctionTable();
Debug.WriteLine("Function table:");
Debug.WriteLine(string.Join(", ", from a in addrs select string.Format($"0x{a:X8}")));
foreach (var loc in addrs) {
var (code, metadata) = ConsiderCode(subImage, loc);
var (code, metadata) = ConsiderCode(Image, loc);
if (code != 0) {
RegistrationFunctionPointer = loc + subImage.GlobalOffset;
RegistrationFunctionPointer = loc + Image.GlobalOffset;
Console.WriteLine("Required structures acquired from code heuristics. Initialization function: 0x{0:X16}", RegistrationFunctionPointer);
Configure(subImage, code, metadata);
Configure(code, metadata);
return true;
}
}
@@ -159,27 +195,21 @@ namespace Il2CppInspector
return false;
}
private void Configure(IFileFormatReader image, ulong codeRegistration, ulong metadataRegistration) {
private void Configure(ulong codeRegistration, ulong metadataRegistration) {
// Store locations
CodeRegistrationPointer = codeRegistration;
MetadataRegistrationPointer = metadataRegistration;
Console.WriteLine("CodeRegistration struct found at 0x{0:X16} (file offset 0x{1:X8})", image.Bits == 32 ? codeRegistration & 0xffff_ffff : codeRegistration, image.MapVATR(codeRegistration));
Console.WriteLine("MetadataRegistration struct found at 0x{0:X16} (file offset 0x{1:X8})", image.Bits == 32 ? metadataRegistration & 0xffff_ffff : metadataRegistration, image.MapVATR(metadataRegistration));
// Set width of long (convert to sizeof(int) for 32-bit files)
if (image.Bits == 32) {
image.Stream.PrimitiveMappings.Add(typeof(long), typeof(int));
image.Stream.PrimitiveMappings.Add(typeof(ulong), typeof(uint));
}
Console.WriteLine("CodeRegistration struct found at 0x{0:X16} (file offset 0x{1:X8})", Image.Bits == 32 ? codeRegistration & 0xffff_ffff : codeRegistration, Image.MapVATR(codeRegistration));
Console.WriteLine("MetadataRegistration struct found at 0x{0:X16} (file offset 0x{1:X8})", Image.Bits == 32 ? metadataRegistration & 0xffff_ffff : metadataRegistration, Image.MapVATR(metadataRegistration));
// Root structures from which we find everything else
CodeRegistration = image.ReadMappedObject<Il2CppCodeRegistration>(codeRegistration);
MetadataRegistration = image.ReadMappedObject<Il2CppMetadataRegistration>(metadataRegistration);
CodeRegistration = Image.ReadMappedObject<Il2CppCodeRegistration>(codeRegistration);
MetadataRegistration = Image.ReadMappedObject<Il2CppMetadataRegistration>(metadataRegistration);
// The global method pointer list was deprecated in v24.2 in favour of Il2CppCodeGenModule
if (Image.Version <= 24.1)
GlobalMethodPointers = image.ReadMappedArray<ulong>(CodeRegistration.pmethodPointers, (int) CodeRegistration.methodPointersCount);
GlobalMethodPointers = Image.ReadMappedArray<ulong>(CodeRegistration.pmethodPointers, (int) CodeRegistration.methodPointersCount);
// After v24 method pointers and RGCTX data were stored in Il2CppCodeGenModules
if (Image.Version >= 24.2) {
@@ -189,36 +219,36 @@ namespace Il2CppInspector
// if this changes we'll have to get smarter about disambiguating these two.
if (CodeRegistration.codeGenModulesCount == 0) {
Image.Version = 24.3;
CodeRegistration = image.ReadMappedObject<Il2CppCodeRegistration>(codeRegistration);
CodeRegistration = Image.ReadMappedObject<Il2CppCodeRegistration>(codeRegistration);
}
// Array of pointers to Il2CppCodeGenModule
var codeGenModulePointers = image.ReadMappedArray<ulong>(CodeRegistration.pcodeGenModules, (int) CodeRegistration.codeGenModulesCount);
var modules = image.ReadMappedObjectPointerArray<Il2CppCodeGenModule>(CodeRegistration.pcodeGenModules, (int) CodeRegistration.codeGenModulesCount);
var codeGenModulePointers = Image.ReadMappedArray<ulong>(CodeRegistration.pcodeGenModules, (int) CodeRegistration.codeGenModulesCount);
var modules = Image.ReadMappedObjectPointerArray<Il2CppCodeGenModule>(CodeRegistration.pcodeGenModules, (int) CodeRegistration.codeGenModulesCount);
foreach (var mp in modules.Zip(codeGenModulePointers, (m, p) => new { Module = m, Pointer = p })) {
var module = mp.Module;
var name = image.ReadMappedNullTerminatedString(module.moduleName);
var name = Image.ReadMappedNullTerminatedString(module.moduleName);
Modules.Add(name, module);
CodeGenModulePointers.Add(name, mp.Pointer);
// Read method pointers
ModuleMethodPointers.Add(module, image.ReadMappedArray<ulong>(module.methodPointers, (int) module.methodPointerCount));
ModuleMethodPointers.Add(module, Image.ReadMappedArray<ulong>(module.methodPointers, (int) module.methodPointerCount));
// Read method invoker pointer indices - one per method
MethodInvokerIndices.Add(module, image.ReadMappedArray<int>(module.invokerIndices, (int) module.methodPointerCount));
MethodInvokerIndices.Add(module, Image.ReadMappedArray<int>(module.invokerIndices, (int) module.methodPointerCount));
}
}
// Field offset data. Metadata <=21.x uses a value-type array; >=21.x uses a pointer array
// Versions from 22 onwards use an array of pointers in Binary.FieldOffsetData
bool fieldOffsetsArePointers = (image.Version >= 22);
bool fieldOffsetsArePointers = (Image.Version >= 22);
// Some variants of 21 also use an array of pointers
if (image.Version == 21) {
var fieldTest = image.ReadMappedWordArray(MetadataRegistration.pfieldOffsets, 6);
if (Image.Version == 21) {
var fieldTest = Image.ReadMappedWordArray(MetadataRegistration.pfieldOffsets, 6);
// We detect this by relying on the fact Module, Object, ValueType, Attribute, _Attribute and Int32
// are always the first six defined types, and that all but Int32 have no fields
@@ -227,20 +257,20 @@ namespace Il2CppInspector
// All older versions use values directly in the array
if (!fieldOffsetsArePointers)
FieldOffsets = image.ReadMappedArray<uint>(MetadataRegistration.pfieldOffsets, (int)MetadataRegistration.fieldOffsetsCount);
FieldOffsets = Image.ReadMappedArray<uint>(MetadataRegistration.pfieldOffsets, (int)MetadataRegistration.fieldOffsetsCount);
else
FieldOffsetPointers = image.ReadMappedWordArray(MetadataRegistration.pfieldOffsets, (int)MetadataRegistration.fieldOffsetsCount);
FieldOffsetPointers = Image.ReadMappedWordArray(MetadataRegistration.pfieldOffsets, (int)MetadataRegistration.fieldOffsetsCount);
// Type references (pointer array)
var typeRefPointers = image.ReadMappedArray<ulong>(MetadataRegistration.ptypes, (int) MetadataRegistration.typesCount);
var typeRefPointers = Image.ReadMappedArray<ulong>(MetadataRegistration.ptypes, (int) MetadataRegistration.typesCount);
TypeReferenceIndicesByAddress = typeRefPointers.Zip(Enumerable.Range(0, typeRefPointers.Length), (a, i) => new { a, i }).ToDictionary(x => x.a, x => x.i);
TypeReferences = image.ReadMappedObjectPointerArray<Il2CppType>(MetadataRegistration.ptypes, (int) MetadataRegistration.typesCount);
TypeReferences = Image.ReadMappedObjectPointerArray<Il2CppType>(MetadataRegistration.ptypes, (int) MetadataRegistration.typesCount);
// Custom attribute constructors (function pointers)
CustomAttributeGenerators = image.ReadMappedArray<ulong>(CodeRegistration.customAttributeGenerators, (int) CodeRegistration.customAttributeCount);
CustomAttributeGenerators = Image.ReadMappedArray<ulong>(CodeRegistration.customAttributeGenerators, (int) CodeRegistration.customAttributeCount);
// Method.Invoke function pointers
MethodInvokePointers = image.ReadMappedArray<ulong>(CodeRegistration.invokerPointers, (int) CodeRegistration.invokerPointersCount);
MethodInvokePointers = Image.ReadMappedArray<ulong>(CodeRegistration.invokerPointers, (int) CodeRegistration.invokerPointersCount);
// TODO: Function pointers as shown below
// reversePInvokeWrappers
@@ -250,18 +280,18 @@ namespace Il2CppInspector
// >=23: interopData
if (Image.Version < 19) {
VTableMethodReferences = image.ReadMappedArray<uint>(MetadataRegistration.methodReferences, (int)MetadataRegistration.methodReferencesCount);
VTableMethodReferences = Image.ReadMappedArray<uint>(MetadataRegistration.methodReferences, (int)MetadataRegistration.methodReferencesCount);
}
// Generic type and method specs (open and closed constructed types)
MethodSpecs = image.ReadMappedArray<Il2CppMethodSpec>(MetadataRegistration.methodSpecs, (int) MetadataRegistration.methodSpecsCount);
MethodSpecs = Image.ReadMappedArray<Il2CppMethodSpec>(MetadataRegistration.methodSpecs, (int) MetadataRegistration.methodSpecsCount);
// Concrete generic class and method signatures
GenericInstances = image.ReadMappedObjectPointerArray<Il2CppGenericInst>(MetadataRegistration.genericInsts, (int) MetadataRegistration.genericInstsCount);
GenericInstances = Image.ReadMappedObjectPointerArray<Il2CppGenericInst>(MetadataRegistration.genericInsts, (int) MetadataRegistration.genericInstsCount);
// Concrete generic method pointers
var genericMethodPointers = image.ReadMappedArray<ulong>(CodeRegistration.genericMethodPointers, (int) CodeRegistration.genericMethodPointersCount);
var genericMethodTable = image.ReadMappedArray<Il2CppGenericMethodFunctionsDefinitions>(MetadataRegistration.genericMethodTable, (int) MetadataRegistration.genericMethodTableCount);
var genericMethodPointers = Image.ReadMappedArray<ulong>(CodeRegistration.genericMethodPointers, (int) CodeRegistration.genericMethodPointersCount);
var genericMethodTable = Image.ReadMappedArray<Il2CppGenericMethodFunctionsDefinitions>(MetadataRegistration.genericMethodTable, (int) MetadataRegistration.genericMethodTableCount);
foreach (var tableEntry in genericMethodTable) {
GenericMethodPointers.Add(MethodSpecs[tableEntry.genericMethodIndex], genericMethodPointers[tableEntry.indices.methodIndex]);
GenericMethodInvokerIndices.Add(MethodSpecs[tableEntry.genericMethodIndex], tableEntry.indices.invokerIndex);

2
Il2CppInspector.Common/IL2CPP/Il2CppInspector.cs
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@@ -409,7 +409,7 @@ namespace Il2CppInspector
// Architecture-agnostic load attempt
try {
if (Il2CppBinary.Load(image, metadata.Version) is Il2CppBinary binary) {
if (Il2CppBinary.Load(image, metadata) is Il2CppBinary binary) {
Console.WriteLine("IL2CPP binary version " + image.Version);
processors.Add(new Il2CppInspector(binary, metadata));

163
Il2CppInspector.Common/IL2CPP/ImageScan.cs Normal file
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@@ -0,0 +1,163 @@
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using NoisyCowStudios.Bin2Object;
namespace Il2CppInspector
{
partial class Il2CppBinary
{
// Find a sequence of bytes
private int FindBytes(byte[] blob, byte[] signature, int step = 1, int startOffset = 0) {
int sigMatch = 0;
int foundOffset = -1;
for (int p = startOffset; p < blob.Length - signature.Length && foundOffset == -1; p += sigMatch == 0? step : 1) {
sigMatch = blob[p] != signature[sigMatch] ? 0 : ++sigMatch;
if (sigMatch == 0)
p = p - p % step + step;
if (sigMatch == 0 && blob[p] == signature[0])
sigMatch++;
if (sigMatch == signature.Length)
foundOffset = p + 1 - signature.Length;
}
return foundOffset;
}
// Find all occurrences of a sequence of bytes
private IEnumerable<uint> FindAllBytes(byte[] blob, byte[] signature, int step = 0) {
var ptrs = new List<uint>();
var offset = 0;
while (offset != -1) {
offset = FindBytes(blob, signature, step != 0 ? step : Image.Bits / 4, offset);
if (offset != -1) {
yield return (uint) offset;
offset += Image.Bits / 4;
}
}
}
// Find strings
private IEnumerable<uint> FindAllStrings(byte[] blob, string str) => FindAllBytes(blob, Encoding.ASCII.GetBytes(str), 1);
// Find 32-bit words
private IEnumerable<uint> FindAllDWords(byte[] blob, uint word) => FindAllBytes(blob, BitConverter.GetBytes(word), 4);
// Find 64-bit words
private IEnumerable<uint> FindAllQWords(byte[] blob, ulong word) => FindAllBytes(blob, BitConverter.GetBytes(word), 8);
// Find words for the current binary size
private IEnumerable<uint> FindAllWords(byte[] blob, ulong word)
=> Image.Bits switch {
32 => FindAllDWords(blob, (uint) word),
64 => FindAllQWords(blob, word),
_ => throw new InvalidOperationException("Invalid architecture bit size")
};
// Find all valid virtual address pointers to a virtual address
private IEnumerable<ulong> FindAllMappedWords(byte[] blob, ulong va) {
var fileOffsets = FindAllWords(blob, va);
foreach (var offset in fileOffsets)
if (Image.TryMapFileOffsetToVA(offset, out va))
yield return va;
}
// Find all valid virtual address pointers to a set of virtual addresses
private IEnumerable<ulong> FindAllMappedWords(byte[] blob, IEnumerable<ulong> va) => va.SelectMany(a => FindAllMappedWords(blob, a));
// Find all valid pointer chains to a set of virtual addresses with the specified number of indirections
private IEnumerable<ulong> FindAllPointerChains(byte[] blob, IEnumerable<ulong> va, int indirections) {
IEnumerable<ulong> vas = va;
for (int i = 0; i < indirections; i++)
vas = FindAllMappedWords(blob, vas);
return vas;
}
// Scan the image for the needed data structures
private (ulong, ulong) ImageScan(Metadata metadata) {
Image.Position = 0;
var imageBytes = Image.ReadBytes((int) Image.Length);
var ptrSize = (uint) Image.Bits / 8;
ulong codeRegistration = 0;
IEnumerable<ulong> vas;
// Find CodeRegistration
// >= 24.2
if (metadata.Version >= 24.2) {
var offsets = FindAllStrings(imageBytes, "mscorlib.dll\0");
vas = offsets.Select(o => Image.MapFileOffsetToVA(o));
// Unwind from string pointer -> CodeGenModule -> CodeGenModules -> CodeRegistration + x
vas = FindAllPointerChains(imageBytes, vas, 3);
if (!vas.Any())
return (0, 0);
if (vas.Count() > 1)
throw new InvalidOperationException("More than one valid pointer chain found during data heuristics");
// pCodeGenModules is the last field in CodeRegistration so we subtract the size of one pointer from the struct size
codeRegistration = vas.First() - ((ulong) Metadata.Sizeof(typeof(Il2CppCodeRegistration), Image.Version, Image.Bits / 8) - ptrSize);
// In v24.3, windowsRuntimeFactoryTable collides with codeGenModules. So far no samples have had windowsRuntimeFactoryCount > 0;
// if this changes we'll have to get smarter about disambiguating these two.
var cr = Image.ReadMappedObject<Il2CppCodeRegistration>(codeRegistration);
if (Image.Version == 24.2 && cr.interopDataCount == 0) {
Image.Version = 24.3;
codeRegistration -= ptrSize * 2; // two extra words for WindowsRuntimeFactory
}
}
// Find CodeRegistration
// <= 24.1
else {
// The first item in CodeRegistration is the total number of method pointers
vas = FindAllMappedWords(imageBytes, (ulong) metadata.Methods.Count(m => (uint) m.methodIndex != 0xffff_ffff));
if (!vas.Any())
return (0, 0);
// The count of method pointers will be followed some bytes later by
// the count of custom attribute generators; the distance between them
// depends on the il2cpp version so we just use ReadMappedObject to simplify the math
foreach (var va in vas) {
var cr = Image.ReadMappedObject<Il2CppCodeRegistration>(va);
if (cr.customAttributeCount == metadata.AttributeTypeRanges.Length)
codeRegistration = va;
}
if (codeRegistration == 0)
return (0, 0);
}
// Find MetadataRegistration
// >= 19
var metadataRegistration = 0ul;
// Find TypeDefinitionsSizesCount (4th last field) then work back to the start of the struct
// This saves us from guessing where metadataUsagesCount is later
var mrSize = (ulong) Metadata.Sizeof(typeof(Il2CppMetadataRegistration), Image.Version, Image.Bits / 8);
vas = FindAllMappedWords(imageBytes, (ulong) metadata.Types.Length).Select(a => a - mrSize + ptrSize * 4);
foreach (var va in vas) {
var mr = Image.ReadMappedObject<Il2CppMetadataRegistration>(va);
if (mr.metadataUsagesCount == (ulong) metadata.MetadataUsageLists.Length)
metadataRegistration = va;
}
if (metadataRegistration == 0)
return (0, 0);
return (codeRegistration, metadataRegistration);
}
}
}

2
Il2CppInspector.GUI/App.xaml.cs
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@@ -90,7 +90,7 @@ namespace Il2CppInspectorGUI
// Architecture-agnostic load attempt
try {
// If we can't load the IL2CPP data here, it's probably packed or obfuscated; ignore it
if (Il2CppBinary.Load(image, metadata.Version) is Il2CppBinary binary) {
if (Il2CppBinary.Load(image, metadata) is Il2CppBinary binary) {
var inspector = new Inspector(binary, metadata);
// Build type model