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IL2CPP: Abstract binary field order reconstruction to plugin

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This commit is contained in:
Katy Coe
2021-01-12 14:31:14 +01:00
parent 5c66889e52
commit c56bd26e4b
2 changed files with 23 additions and 837 deletions
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48
Il2CppInspector.Common/IL2CPP/Il2CppBinary.cs
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@@ -17,11 +17,16 @@ namespace Il2CppInspector
{ {
public abstract partial class Il2CppBinary public abstract partial class Il2CppBinary
{ {
// File image
public IFileFormatStream Image { get; } public IFileFormatStream Image { get; }
// The metadata associed with this binary - this is optional and may be null. Contents should not be modified
public Metadata Metadata { get; private set; }
// IL2CPP-only API exports with decrypted names // IL2CPP-only API exports with decrypted names
public Dictionary<string, ulong> APIExports { get; } = new Dictionary<string, ulong>(); public Dictionary<string, ulong> APIExports { get; } = new Dictionary<string, ulong>();
// Binary metadata structures
public Il2CppCodeRegistration CodeRegistration { get; protected set; } public Il2CppCodeRegistration CodeRegistration { get; protected set; }
public Il2CppMetadataRegistration MetadataRegistration { get; protected set; } public Il2CppMetadataRegistration MetadataRegistration { get; protected set; }
@@ -159,7 +164,7 @@ namespace Il2CppInspector
public bool FindRegistrationStructs(double metadataVersion) { public bool FindRegistrationStructs(double metadataVersion) {
Image.Version = metadataVersion; Image.Version = metadataVersion;
if (!((FindMetadataFromSymbols() ?? FindMetadataFromCode()) is (ulong code, ulong meta))) if (!((FindMetadataFromSymbols() ?? FindMetadataFromCode() ?? FindMetadataFromData()) is (ulong code, ulong meta)))
return false; return false;
TryPrepareMetadata(code, meta); TryPrepareMetadata(code, meta);
@@ -168,13 +173,8 @@ namespace Il2CppInspector
// Initialize binary with a global-metadata.dat available // Initialize binary with a global-metadata.dat available
public bool FindRegistrationStructs(Metadata metadata) { public bool FindRegistrationStructs(Metadata metadata) {
Image.Version = metadata.Version; Metadata = metadata;
return FindRegistrationStructs(metadata.Version);
if (!((FindMetadataFromSymbols() ?? FindMetadataFromCode() ?? FindMetadataFromData(metadata)) is (ulong code, ulong meta)))
return false;
TryPrepareMetadata(code, meta, metadata);
return true;
} }
// Try to find data structures via symbol table lookup // Try to find data structures via symbol table lookup
@@ -230,8 +230,11 @@ namespace Il2CppInspector
// Try to find data structures via data heuristics // Try to find data structures via data heuristics
// Requires succeesful global-metadata.dat analysis first // Requires succeesful global-metadata.dat analysis first
private (ulong, ulong)? FindMetadataFromData(Metadata metadata) { private (ulong, ulong)? FindMetadataFromData() {
var (codePtr, metadataPtr) = ImageScan(metadata); if (Metadata == null)
return null;
var (codePtr, metadataPtr) = ImageScan(Metadata);
if (codePtr == 0) { if (codePtr == 0) {
Console.WriteLine("No matches via data heuristics"); Console.WriteLine("No matches via data heuristics");
return null; return null;
@@ -246,9 +249,9 @@ namespace Il2CppInspector
// Load all of the discovered metadata in the binary // Load all of the discovered metadata in the binary
private void TryPrepareMetadata(ulong codeRegistration, ulong metadataRegistration, Metadata metadata = null) { private void TryPrepareMetadata(ulong codeRegistration, ulong metadataRegistration) {
try { try {
PrepareMetadata(codeRegistration, metadataRegistration, metadata); PrepareMetadata(codeRegistration, metadataRegistration);
} }
catch (Exception ex) when (!(ex is NotSupportedException)) { catch (Exception ex) when (!(ex is NotSupportedException)) {
throw new InvalidOperationException($"Could not analyze IL2CPP data. Ensure that the latest core plugins package is installed and all core plugins are enabled before filing a bug report. The error was: {ex.Message}", ex); throw new InvalidOperationException($"Could not analyze IL2CPP data. Ensure that the latest core plugins package is installed and all core plugins are enabled before filing a bug report. The error was: {ex.Message}", ex);
@@ -256,7 +259,7 @@ namespace Il2CppInspector
} }
// Load all of the discovered metadata in the binary // Load all of the discovered metadata in the binary
private void PrepareMetadata(ulong codeRegistration, ulong metadataRegistration, Metadata metadata = null) { private void PrepareMetadata(ulong codeRegistration, ulong metadataRegistration) {
// Store locations // Store locations
CodeRegistrationPointer = codeRegistration; CodeRegistrationPointer = codeRegistration;
MetadataRegistrationPointer = metadataRegistration; MetadataRegistrationPointer = metadataRegistration;
@@ -280,18 +283,13 @@ namespace Il2CppInspector
* typeRefPointers must be a series of pointers in __const * typeRefPointers must be a series of pointers in __const
* MethodInvokePointers must be a series of pointers in __text or .text, and in sequential order * MethodInvokePointers must be a series of pointers in __text or .text, and in sequential order
*/ */
for (var pass = 0; pass <= 1; pass++) if (MetadataRegistration.typesCount < MetadataRegistration.typeDefinitionsSizesCount
if (MetadataRegistration.typesCount < MetadataRegistration.typeDefinitionsSizesCount || MetadataRegistration.genericMethodTableCount < MetadataRegistration.genericInstsCount
|| MetadataRegistration.genericMethodTableCount < MetadataRegistration.genericInstsCount || CodeRegistration.reversePInvokeWrapperCount > 0x4000
|| CodeRegistration.reversePInvokeWrapperCount > 0x4000 || CodeRegistration.unresolvedVirtualCallCount > 0x4000 // >= 22
|| CodeRegistration.unresolvedVirtualCallCount > 0x4000 // >= 22 || CodeRegistration.interopDataCount > 0x1000 // >= 23
|| CodeRegistration.interopDataCount > 0x1000 // >= 23 || (Image.Version <= 24.1 && CodeRegistration.invokerPointersCount > CodeRegistration.methodPointersCount))
|| (Image.Version <= 24.1 && CodeRegistration.invokerPointersCount > CodeRegistration.methodPointersCount)) throw new NotSupportedException("The detected Il2CppCodeRegistration / Il2CppMetadataRegistration structs do not pass validation. This may mean that their fields have been re-ordered as a form of obfuscation and Il2CppInspector has not been able to restore the original order automatically. Consider re-ordering the fields in Il2CppBinaryClasses.cs and try again.");
// Restore the field order in CodeRegistration and MetadataRegistration if they have been re-ordered for obfuscation
if (pass == 0)
ReconstructMetadata(metadata);
else
throw new NotSupportedException("The detected Il2CppCodeRegistration / Il2CppMetadataRegistration structs do not pass validation. This may mean that their fields have been re-ordered as a form of obfuscation and Il2CppInspector has not been able to restore the original order automatically. Consider re-ordering the fields in Il2CppBinaryClasses.cs and try again.");
// The global method pointer list was deprecated in v24.2 in favour of Il2CppCodeGenModule // The global method pointer list was deprecated in v24.2 in favour of Il2CppCodeGenModule
if (Image.Version <= 24.1) if (Image.Version <= 24.1)

812
Il2CppInspector.Common/IL2CPP/ReconstructMetadata.cs
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@@ -1,812 +0,0 @@
/*
Copyright 2020-2021 Katy Coe - http://www.djkaty.com - https://github.com/djkaty
All rights reserved.
*/
using System;
using System.Collections.Generic;
using System.Linq;
using NoisyCowStudios.Bin2Object;
namespace Il2CppInspector
{
// Some IL2CPP applications obfuscate the order of fields in Il2CppCodeRegistration and Il2CppMetadataRegistration
// specifically to defeat IL2CPP reverse engineering tools. We make an imperfect attempt to defeat this below
// by re-arranging the fields back into their original order. This can be greatly improved and much more deeply analyzed.
// Devs: Please don't burn development resources on obfuscation. It's a waste of your time and mine. Spend it making good games instead.
partial class Il2CppBinary
{
// Loads all the pointers and counts for the specified IL2CPP metadata type regardless of version or word size into two arrays
// Sorts the pointers and calculates the maximum number of bytes between each,
// optinally constrained by the highest count in the IL2CPP metadata type and by the end of the nearest section in the image.
// Returns an array of the pointers in sorted order and an array of maximum byte/word counts with corresponding indexes
private (List<ulong> ptrs, List<int> limits, List<int> originalCounts)
preparePointerList(Metadata metadata, Type type, ulong typePtr, IEnumerable<Section> sections, bool itemsAreWords = false) {
// Get number of pointer/count pairs in each structure
var itemsCount = metadata.Sizeof(type, Image.Version, Image.Bits / 8) / (Image.Bits / 8) / 2;
// Read pointers and counts as two lists
var itemArray = Image.ReadMappedArray<ulong>(typePtr, itemsCount * 2);
var itemPtrs = Enumerable.Range(0, itemArray.Length / 2).Select(i => itemArray[i*2 + 1]).ToList();
var itemCounts = Enumerable.Range(0, itemArray.Length / 2).Select(i => (int) itemArray[i*2]).ToList();
// Get maximum number of bytes/count between each pair of pointers
// None of the maximums should be higher than the maximum count specified in the struct
// Rule out zero pointers for no longer used fields (eg. customAttributeGenerators >=27)
var itemMaxBytes = itemsAreWords? itemCounts.Max() * (Image.Bits / 8) : int.MaxValue;
var itemPtrsOrdered = itemPtrs.Where(p => p != 0).OrderBy(p => p).ToList();
var itemCountLimits = itemPtrsOrdered
.Zip(itemPtrsOrdered.Skip(1), (a, b) => Math.Min((int) (b - a), itemMaxBytes))
.Append(itemMaxBytes)
.ToList();
// Prevent a pointer list from overrunning the end of a section
for (var i = 0; i < itemPtrsOrdered.Count; i++) {
var section = sections.FirstOrDefault(s => s.VirtualStart <= itemPtrsOrdered[i] && s.VirtualEnd >= itemPtrsOrdered[i]);
if (section != null) {
var maxSize = (int) (section.VirtualEnd + 1 - itemPtrsOrdered[i]);
itemCountLimits[i] = Math.Min(itemCountLimits[i], maxSize);
}
}
// Convert byte sizes to words if applicable
if (itemsAreWords)
itemCountLimits = itemCountLimits.Select(i => i / (Image.Bits / 8)).ToList();
return (itemPtrsOrdered, itemCountLimits, itemCounts);
}
// Reconstruct Il2CppCodeRegistration and Il2CppMetadataRegistration into their original, unobfuscated field order
// Supports metadata >=19, <=24.1 (TODO: add CodeGenModules to support <27)
private void ReconstructMetadata(Metadata metadata) {
// Don't cause corruption in unsupported versions
if (Image.Version < 19 || Image.Version > 24.1)
return;
// If the section table is not available, give up and do nothing
if (!Image.TryGetSections(out var sections))
return;
// Get relevant image sections
var codeSections = sections.Where(s => s.IsExec).ToList();
var dataSections = sections.Where(s => s.IsData && !s.IsBSS).ToList();
var bssSections = sections.Where(s => s.IsBSS).ToList();
// For PE files, data sections in memory can be larger than in the image
// The unmapped portion is BSS data so create fake sections for this and shrink the existing ones
foreach (var section in dataSections) {
var virtualSize = section.VirtualEnd - section.VirtualStart;
var imageSize = section.ImageEnd - section.ImageStart;
if (imageSize < virtualSize) {
var bssEnd = section.VirtualEnd;
section.VirtualEnd = section.VirtualStart + imageSize;
bssSections.Add(new Section {
VirtualStart = section.VirtualStart + imageSize + 1,
VirtualEnd = bssEnd,
ImageStart = 0,
ImageEnd = 0,
IsExec = false,
IsData = false,
IsBSS = true,
Name = ".bss"
});
}
}
// Fetch and sanitize our pointer and count lists
var (codePtrsOrdered, codeCountLimits, codeCounts) = preparePointerList(metadata, typeof(Il2CppCodeRegistration), CodeRegistrationPointer, dataSections, true);
var (metaPtrsOrdered, metaCountLimits, metaCounts) = preparePointerList(metadata, typeof(Il2CppMetadataRegistration), MetadataRegistrationPointer, dataSections);
// Progress updater
var maxProgress = codeCounts.Sum() + metaCounts.Sum();
var currentProgress = 0;
void UpdateProgress(int workDone) {
currentProgress += workDone;
StatusUpdate($"Reconstructing obfuscated registration metadata ({currentProgress * 100 / maxProgress:F0}%)");
}
Console.WriteLine("Reconstructing obfuscated registration metadata...");
UpdateProgress(0);
// Counts from minimal compiles
// v21 test project:
// genericMethodPointers - 0x07B5, customAttributeGenerators - 0x0747, invokerPointers - 0x04DB, methodPointers - 0x226A
// v24.1 empty Unity project:
// genericMethodPointers - 0x0C15, customAttributeGenerators - 0x0A21, invokerPointers - 0x0646, methodPointers - 0x268B
// v24.2 without Unity:
// genericMethodPointers - 0x2EC2, customAttributeGenerators - 0x15EC, invokerPointers - 0x0B65
// v21 test project:
// genericInsts - 0x0150, genericMethodTable - 0x0805, types - 0x1509, methodSpecs - 0x08D8, fieldOffsets - 0x0569, metadataUsages - 0x1370
// v24.1 empty Unity project:
// genericInsts - 0x025E, genericMethodTable - 0x0E3F, types - 0x2632, methodSpecs - 0x0FD4, fieldOffsets - 0x0839, metadataUsages - 0x1850
// v24.2 without Unity:
// genericInsts - 0x06D4, genericMethodTable - 0x31E8, types - 0x318A, methodSpecs - 0x3AD8, fieldOffsets - 0x0B3D, metadataUsages - 0x3BA8
// Some heuristic constants
// The maximum address gap in a sequential list of pointers before the sequence is considered to be 'broken'
const int MAX_SEQUENCE_GAP = 0x10000;
// The minimum number of Il2CppTypes we expect
const int MIN_TYPES = 0x1400;
// The maximum number of generic type parameters we expect for any class or method
const int MAX_GENERIC_TYPE_PARAMETERS = 32;
// The minimum number of Il2CppGenericInsts we expect
const int MIN_GENERIC_INSTANCES = 0x140;
// The maximum number of generic methods in generic classes we expect to find in a single sequence of Il2CppMethodSpec
// The highest we have seen in a production app is 3414; the next highest 2013, the next highest 1380
// 300-600 is typical
const int MAX_SEQUENTIAL_GENERIC_CLASS_METHODS = 5000;
// The minimum number of Il2CppMethodSpecs we expect
const int MIN_METHOD_SPECS = 0x0800;
// The minimum number of Il2CppGenericMethodFunctionsDefinitions we expect
const int MIN_GENERIC_METHOD_TABLE = 0x600;
// The minimum spread of values in an instance of Il2CppGenericMethodFunctionsDefinitions under which the threshold counter is incremented
const int MIN_GENERIC_METHOD_TABLE_SPREAD = 100;
// The maximum number of instances in a row with a spread under the minimum we expect to find in a single sequence
const int MAX_SEQUENTIAL_GENERIC_METHOD_TABLE_LOW_SPREAD_INSTANCES = 100;
// The minimum number of field offsets we expect
const int MIN_FIELD_OFFSETS = 0x400;
// The maximum value for a field offset
const int MAX_FIELD_OFFSET = 0x100000;
// The minimum and maximum proportions of inversions we expect in a non-pointer field offset list
// Example values: 0.385, 0.415, 0.468
const double MIN_FIELD_OFFSET_INVERSION = 0.3;
const double MAX_FIELD_OFFSET_INVERSION = 0.6;
// The minimum and maximum proportions of zeroes we expect in a non-pointer field offset list
// Example values: 0.116, 0.179, 0.303, 0.321, 0.385
// The main thing is to force enough zeroes to prevent it being confused with a list with no zeroes (eg. genericClasses)
const double MIN_FIELD_OFFSET_ZEROES = 0.10;
const double MAX_FIELD_OFFSET_ZEROES = 0.5;
// The maximum allowed gap between two field offsets
const int MAX_FIELD_OFFSET_GAP = 0x10000;
// Things we need from Il2CppCodeRegistration
// methodPointers (<=24.1) -> list of function pointers (1st count) (non-sequential)
// genericMethodPointers -> list of function pointers (first IS zero) (2nd count) (not sequential)
// customAttributeGenerators (<27) -> list of function pointers (first MAY be zero) (2nd count) (sequential)
// invokerPointers -> list of function pointers (3rd count) (sequential)
// codeGenModules (>=24.2) -> list of Il2CppCodeGenModule* // TODO: We only support <=24.1 currently
// (interopData will probably have 6 sequential pointers since Il2CppInteropData starts with 5 function pointers and a GUID)
// Let's see how many valid pointers and sequential valid pointers we actually find at each address
// Scan each pointer address for valid list of function pointers and sort into size order
// Consider the sequence to be broken if there is a gap over a certain threshold
var fnPtrs = new SortedDictionary<ulong, int>();
var seqFnPtrs = new SortedDictionary<ulong, int>();
for (var i = 0; i < codePtrsOrdered.Count; i++) {
// Non-sequential valid pointers
var ptrs = Image.ReadMappedArray<ulong>(codePtrsOrdered[i], codeCountLimits[i]);
var foundCount = ptrs.TakeWhile(p => codeSections.Any(s => p >= s.VirtualStart && p <= s.VirtualEnd || p == 0)).Count();
// Prune count of trailing zero pointers
while (foundCount > 0 && ptrs[foundCount - 1] == 0ul)
foundCount--;
fnPtrs.Add(codePtrsOrdered[i], foundCount);
// Binaries compiled with MSVC (generally PE files) use /OPT:ICF by default (enable ICF) so this won't work.
// For these binaries, we'll use a different selection strategy below
if (Image is PEReader)
continue;
// Sequential valid pointers (a subset of non-sequential valid pointers)
if (foundCount > 0) {
foundCount = ptrs.Take(foundCount)
.Zip(ptrs.Take(foundCount).Skip(1), (a, b) => (a, b))
.TakeWhile(t => ((long) t.b - (long) t.a >= 0 || t.b == 0)
&& ((long) t.b - (long) t.a < MAX_SEQUENCE_GAP || t.a == 0)
// Disallow two zero pointers in a row
&& (t.a != 0 || t.b != 0))
.Count() + 1;
// Prune count of trailing zero pointers
while (foundCount > 0 && ptrs[foundCount - 1] == 0ul)
foundCount--;
}
seqFnPtrs.Add(codePtrsOrdered[i], foundCount);
UpdateProgress(foundCount);
}
KeyValuePair<ulong, int> methodPointers, genericMethodPointers, customAttributeGenerators, invokerPointers;
// Solution without ICF
if (!(Image is PEReader)) {
// The two largest sequential groups are customAttributeGenerators and invokerPointers
var seqLongest = seqFnPtrs.OrderByDescending(kv => kv.Value).Take(2).ToList();
(customAttributeGenerators, invokerPointers) = (seqLongest[0], seqLongest[1]);
// For >=27, customAttributeGenerators is zero and so the largest group is invokerPointers
if (Image.Version >= 27) {
invokerPointers = customAttributeGenerators;
customAttributeGenerators = new KeyValuePair<ulong, int>(0ul, 0);
}
// After removing these from the non-sequential list, the largest groups are methodPointers and genericMethodPointers
var longest = fnPtrs.Except(seqLongest).OrderByDescending(kv => kv.Value).Take(2).ToList();
(methodPointers, genericMethodPointers) = (longest[0], longest[1]);
// For >=24.2, methodPointers is zero and so the largest group is genericMethodPointers
if (Image.Version >= 24.2) {
genericMethodPointers = methodPointers;
methodPointers = new KeyValuePair<ulong, int>(0ul, 0);
}
// Prune genericMethodPointers at 2nd zero (first pointer is always zero)
var gmPtr = Image.ReadMappedArray<ulong>(genericMethodPointers.Key, genericMethodPointers.Value);
var gmZero = Array.IndexOf(gmPtr, 0ul, 1);
if (gmZero != -1)
genericMethodPointers = new KeyValuePair<ulong, int>(genericMethodPointers.Key, gmZero);
}
// Solution with ICF
else {
// Take and remove the first item and assume it's methodPointers for <=24.1, otherwise set to zero
var orderedPtrs = fnPtrs.OrderByDescending(kv => kv.Value).ToList();
if (Image.Version <= 24.1) {
methodPointers = orderedPtrs[0];
orderedPtrs.RemoveAt(0);
} else
methodPointers = new KeyValuePair<ulong, int>(0ul, 0);
// Assume this order is right most of the time
// TODO: generic and custom attribute might be the wrong way round (eg. #102)
(genericMethodPointers, customAttributeGenerators, invokerPointers) = (orderedPtrs[0], orderedPtrs[1], orderedPtrs[2]);
// customAttributeGenerators is removed in metadata >=27
if (Image.Version >= 27) {
invokerPointers = customAttributeGenerators;
customAttributeGenerators = new KeyValuePair<ulong, int>(0ul, 0);
}
}
#region Debugging validation checks
#if false
// Used on non-obfuscated binaries during development to confirm the output is correct
if (methodPointers.Key != CodeRegistration.pmethodPointers)
throw new Exception("Method Pointers incorrect");
if (invokerPointers.Key != CodeRegistration.invokerPointers)
throw new Exception("Invoker Pointers incorrect");
if (customAttributeGenerators.Key != CodeRegistration.customAttributeGenerators)
throw new Exception("Custom attribute generators incorrect");
if (genericMethodPointers.Key != CodeRegistration.genericMethodPointers)
throw new Exception("Generic method pointers incorrect");
if (methodPointers.Value != (int) CodeRegistration.methodPointersCount)
throw new Exception("Count of Method Pointers incorrect");
if (invokerPointers.Value != (int) CodeRegistration.invokerPointersCount)
throw new Exception("Count of Invoker Pointers incorrect");
if (customAttributeGenerators.Value != (int) CodeRegistration.customAttributeCount)
throw new Exception("Count of Custom attribute generators incorrect");
if (genericMethodPointers.Value != (int) CodeRegistration.genericMethodPointersCount)
throw new Exception("Count of Generic method pointers incorrect");
#endif
#endregion
// Things we need from Il2CppMetadataRegistration
// genericInsts -> list of Il2CppGenericInst* (argc is count of Il2CppType* at data pointer argv; datapoint = GenericParameterIndex)
// genericMethodTable -> list of Il2CppGenericMethodFunctionsDefinitions (genericMethodIndex, methodIndex, invokerIndex)
// types -> list of Il2CppType*
// methodSpecs -> list of Il2CppMethodSpec
// methodReferences (<=16) -> list of uint (ignored, we don't support <=16 here)
// fieldOffsets (fieldOffsetsArePointers) -> either a list of data pointers (some zero, some VAs not mappable) to list of uints, or a list of uints
// metadataUsages (>=19, <27) -> list of unmappable data pointers
// We can only perform this re-ordering if we can refer to a loaded global-metadata.dat
if (metadata == null)
return;
// Read in all the required data once since we'll be using nested loops
var metaPtrData = new List<(ulong, int, ulong[], int)>();
for (var i = 0; i < metaPtrsOrdered.Count; i++) {
// Pointers in this list
var ptrs = Image.ReadMappedArray<ulong>(metaPtrsOrdered[i], metaCountLimits[i] / (Image.Bits / 8));
// First set of pointers that point to a data section virtual address
var foundDataPtrsCount = ptrs.TakeWhile(p => dataSections.Any(s => p >= s.VirtualStart && p <= s.VirtualEnd)).Count();
// First set of pointers that can be mapped anywhere into the image
var foundImageMappablePtrsCount = ptrs.TakeWhile(p => Image.TryMapVATR(p, out _)).Count();
#if DEBUG
// First set of pointers that can be mapped into a data section in the image
var mappableDataPtrs = ptrs.Take(foundImageMappablePtrsCount)
.TakeWhile(p => dataSections.Any(s => Image.MapVATR(p) >= s.ImageStart && Image.MapVATR(p) <= s.ImageEnd))
.ToArray();
var foundNonBSSDataPtrsCount = mappableDataPtrs.Length;
if (foundDataPtrsCount != foundNonBSSDataPtrsCount)
throw new Exception($"Pointer count mismatch: {foundDataPtrsCount:x8} / {foundNonBSSDataPtrsCount:x8}");
#endif
metaPtrData.Add((metaPtrsOrdered[i], metaCountLimits[i], ptrs, foundDataPtrsCount));
}
// Items we need to search for
var types = (ptr: 0ul, count: -1);
var genericInsts = (ptr: 0ul, count: -1);
var methodSpecs = (ptr: 0ul, count: -1);
var genericMethodTable = (ptr: 0ul, count: -1);
var metadataUsages = (ptr: 0ul, count: -1);
var fieldOffsets = (ptr: 0ul, count: -1);
var NOT_FOUND = (ptr: 0xfffffffful, count: -1);
// Intermediary items
var typesPtrs = new List<ulong>();
Il2CppMethodSpec[] methodSpec = null;
// IL2CPP doesn't calculate metadataUsagesCount correctly so we do it here
// Adapted from Il2CppInspector.buildMetadataUsages()
var usages = new HashSet<uint>();
// Only on supported metadata versions (>=19, <27)
if (metadata.MetadataUsageLists != null)
foreach (var metadataUsageList in metadata.MetadataUsageLists)
for (var i = 0; i < metadataUsageList.count; i++)
usages.Add(metadata.MetadataUsagePairs[metadataUsageList.start + i].destinationindex);
// Determine what each pointer is
// We need to do this in a certain order because validating some items relies on earlier items
while (metaPtrData.Any()) {
ref var foundItem = ref NOT_FOUND;
(ulong ptr, int count) foundData = (0ul, -1);
// We loop repeatedly through every set of data looking for our next target item,
// remove the matching set from the list and then repeat the outer while loop
// until there is nothing left to find
foreach (var (ptr, limit, ptrs, dataPtrsCount) in metaPtrData) {
foundData = (ptr, 0);
// Test for Il2CppType**
// ---------------------
if (types.count == -1) {
// We don't ever expect there to be less than MIN_TYPES types
if (dataPtrsCount >= MIN_TYPES) {
var testItems = Image.ReadMappedObjectPointerArray<Il2CppType>(ptr, dataPtrsCount);
foreach (var item in testItems) {
// TODO: v27 will fail this because of the bit shifting in Il2CppType.bits
if (item.num_mods != 0)
break;
if (!Enum.IsDefined(typeof(Il2CppTypeEnum), item.type))
break;
if (item.type == Il2CppTypeEnum.IL2CPP_TYPE_END)
break;
// Test datapoint
if (item.type switch {
var t when (t is Il2CppTypeEnum.IL2CPP_TYPE_VALUETYPE || t is Il2CppTypeEnum.IL2CPP_TYPE_CLASS)
&& item.datapoint >= (ulong) metadata.Types.Length => false,
var t when (t is Il2CppTypeEnum.IL2CPP_TYPE_VAR || t is Il2CppTypeEnum.IL2CPP_TYPE_MVAR)
&& item.datapoint >= (ulong) metadata.GenericParameters.Length => false,
var t when (t is Il2CppTypeEnum.IL2CPP_TYPE_PTR || t is Il2CppTypeEnum.IL2CPP_TYPE_SZARRAY)
&& !ptrs.Take(dataPtrsCount).Contains(item.datapoint) => false,
// Untested cases, we could add more here (IL2CPP_TYPE_ARRAY, IL2CPP_TYPE_GENERICINST)
_ => true
})
foundData.count++;
else
break;
}
if (foundData.count >= MIN_TYPES) {
foundItem = ref types;
typesPtrs = ptrs.ToList();
break;
}
}
}
// Test for Il2CppGenericInst**
// ----------------------------
else if (genericInsts.count == -1) {
if (dataPtrsCount >= MIN_GENERIC_INSTANCES) {
var testItems = Image.ReadMappedObjectPointerArray<Il2CppGenericInst>(ptr, dataPtrsCount);
foreach (var item in testItems) {
// Let's pray no generic type has more than this many type parameters
if (item.type_argc > MAX_GENERIC_TYPE_PARAMETERS)
break;
// All the generic type paramters must be in the total list of types,
// ie. typePtrs must be a subset of typesData.Keys
try {
var typePtrs = Image.ReadMappedArray<ulong>(item.type_argv, (int) item.type_argc);
if (typePtrs.Any(p => !typePtrs.Contains(p)))
break;
// Pointers were invalid
}
catch (InvalidOperationException) {
break;
}
foundData.count++;
}
if (foundData.count >= MIN_GENERIC_INSTANCES) {
foundItem = ref genericInsts;
break;
}
}
}
// Test for Il2CppMethodSpec*
// --------------------------
else if (methodSpecs.count == -1) {
var max = limit / metadata.Sizeof(typeof(Il2CppMethodSpec));
if (max >= MIN_METHOD_SPECS) {
var testItems = Image.ReadMappedArray<Il2CppMethodSpec>(ptr, max);
var nonNegativePairs = 0;
foreach (var item in testItems) {
if (item.methodDefinitionIndex < 0 || item.methodDefinitionIndex >= metadata.Methods.Length)
break;
if (item.classIndexIndex < -1 || item.classIndexIndex >= genericInsts.count)
break;
if (item.methodIndexIndex < -1 || item.methodIndexIndex >= genericInsts.count)
break;
// Non-negative pairs shouldn't appear in large groups
nonNegativePairs = item.classIndexIndex != -1 && item.methodIndexIndex != -1 ? nonNegativePairs + 1 : 0;
if (nonNegativePairs > MAX_SEQUENTIAL_GENERIC_CLASS_METHODS)
break;
foundData.count++;
}
// Assumes last methods are not generic methods in generic classes
foundData.count -= nonNegativePairs;
if (foundData.count >= MIN_METHOD_SPECS) {
foundItem = ref methodSpecs;
methodSpec = testItems;
break;
}
}
}
// Test for Il2CppGenericMethodFunctionsDefinitions*
// -------------------------------------------------
else if (genericMethodTable.count == -1) {
var max = limit / metadata.Sizeof(typeof(Il2CppGenericMethodFunctionsDefinitions));
if (max >= MIN_GENERIC_METHOD_TABLE) {
var testItems = Image.ReadMappedArray<Il2CppGenericMethodFunctionsDefinitions>(ptr, max);
var lowSpreadCount = 0;
foreach (var item in testItems) {
if (item.genericMethodIndex < 0 || item.genericMethodIndex >= methodSpecs.count)
break;
if (item.indices.methodIndex < 0 || item.indices.methodIndex >= genericMethodPointers.Value)
break;
if (item.indices.invokerIndex < 0 || item.indices.invokerIndex >= invokerPointers.Value)
break;
// methodIndex is an index into the method pointer table
// For generic type definitions, there is no concrete function so this must be 0xffffffff
// TODO: For >=24.2, we need to use the method token to look up the value in an Il2CppCodeGenModule, not currently implemented
if (Image.Version <= 24.1)
if (metadata.Methods[methodSpec[item.genericMethodIndex].methodDefinitionIndex].methodIndex != -1)
break;
foundData.count++;
// Instances where all the values are clustered should be rare
var spread = Math.Max(Math.Max(item.indices.methodIndex, item.indices.invokerIndex), item.genericMethodIndex)
- Math.Min(Math.Min(item.indices.methodIndex, item.indices.invokerIndex), item.genericMethodIndex);
lowSpreadCount = spread < MIN_GENERIC_METHOD_TABLE_SPREAD ? lowSpreadCount + 1 : 0;
if (lowSpreadCount > MAX_SEQUENTIAL_GENERIC_METHOD_TABLE_LOW_SPREAD_INSTANCES)
break;
}
// Assumes the last instances don't have clustered values
foundData.count -= lowSpreadCount;
if (foundData.count >= MIN_GENERIC_METHOD_TABLE) {
foundItem = ref genericMethodTable;
break;
}
}
}
// Test for metadata usages
// ------------------------
else if (metadataUsages.count == -1) {
// No metadata usages for these versions
if (Image.Version < 19 || Image.Version >= 27) {
foundData.ptr = 0ul;
foundItem = ref metadataUsages;
break;
}
// Metadata usages always map to BSS sections (dataPtrsCount == 0)
// For images dumped from memory, metadata usages must always map to data sections
if ((dataPtrsCount == 0 && limit / (Image.Bits / 8) >= usages.Count)
|| dataPtrsCount >= usages.Count) {
// No null pointers allowed (this test only applies to non-dumped images)
if (ptrs.Take(usages.Count).All(p => p != 0ul)) {
// For normal images, all the pointers must map to a BSS section
// For PE files this relies on our section modding above
// For dumped images, BSS sections are also data sections so we can use the same test
var bssMappableCount = ptrs.Take(usages.Count).Count(p => bssSections.Any(s => p >= s.VirtualStart && p <= s.VirtualEnd));
foundData.count = bssMappableCount;
foundItem = ref metadataUsages;
break;
}
}
}
// Test for field offsets
// ----------------------
else if (fieldOffsets.count == -1) {
// This could be a list of pointers to locally incrementing sequences of uints,
// or it could be a sequence of uints
// Some uints may be zero, but must otherwise never be less than the minimum heap offset of the first parameter
// for the binary's function calling convention, and never greater than the maximum heap offset of the last parameter
// Try as sequence of uints
if (metadata.Version <= 21) {
var max = limit / sizeof(uint);
if (max >= MIN_FIELD_OFFSETS) {
var testItems = Image.ReadMappedArray<uint>(ptr, max);
var previousItem = 0u;
var inversions = 0;
var zeroes = 0;
foreach (var item in testItems) {
if (item > MAX_FIELD_OFFSET && item != 0xffffffff)
break;
if (item > previousItem + MAX_FIELD_OFFSET_GAP && item != 0xffffffff)
break;
// Count zeroes and inversions (equality counts as inversion here since two arguments can't share a heap offset)
if (item <= previousItem)
inversions++;
if (item == 0)
zeroes++;
previousItem = item;
foundData.count++;
}
if (foundData.count >= MIN_FIELD_OFFSETS) {
var inversionsPc = (double) inversions / foundData.count;
var zeroesPc = (double) zeroes / foundData.count;
if (inversionsPc >= MIN_FIELD_OFFSET_INVERSION && inversionsPc <= MAX_FIELD_OFFSET_INVERSION
&& zeroesPc >= MIN_FIELD_OFFSET_ZEROES && zeroesPc <= MAX_FIELD_OFFSET_ZEROES) {
foundItem = ref fieldOffsets;
break;
}
}
}
}
// Try as a sequence of pointers to sets of uints
if (metadata.Version >= 21) {
foundData.count = 0;
var max = limit / (Image.Bits / 8);
if (max >= MIN_FIELD_OFFSETS) {
var testItems = Image.ReadMappedArray<ulong>(ptr, max);
var zeroes = 0;
foreach (var item in testItems) {
// Every pointer must either be zero or mappable into a data or BSS section
if (item != 0ul && !dataSections.Any(s => item >= s.VirtualStart && item < s.VirtualEnd)
&& !bssSections.Any(s => item >= s.VirtualStart && item < s.VirtualEnd))
break;
// Count zeroes
if (item == 0ul)
zeroes++;
// Every valid pointer must point to a series of incrementing offsets until an inversion or a large gap
else if (dataSections.Any(s => item >= s.VirtualStart && item < s.VirtualEnd)) {
Image.Position = Image.MapVATR(item);
var previous = 0u;
var offset = 0u;
var valid = true;
while (offset != 0xffffffff && offset > previous && valid) {
previous = offset;
offset = Image.ReadUInt32();
// Consider a large gap as the end of the sequence
if (offset > previous + MAX_FIELD_OFFSET_GAP && offset != 0xffffffff)
break;
// A few offsets seem to have the top bit set for some reason
if (offset >= previous && (offset & 0x7fffffff) > MAX_FIELD_OFFSET && offset != 0xffffffff)
valid = false;
}
if (!valid)
break;
}
foundData.count++;
}
if (foundData.count >= MIN_FIELD_OFFSETS) {
var zeroesPc = (double) zeroes / foundData.count;
if (zeroesPc >= MIN_FIELD_OFFSET_ZEROES && zeroesPc <= MAX_FIELD_OFFSET_ZEROES) {
foundItem = ref fieldOffsets;
break;
}
}
}
}
}
foundData = (0ul, -1);
}
// We didn't find anything - break to avoid an infinite loop
if (foundItem == NOT_FOUND)
break;
// Remove pointer from list of remaining pointers to test
metaPtrData = metaPtrData.Where(m => foundData.ptr != m.Item1).ToList();
// Select the highest count in the original data that is lower or equal to our found count
// Skip items not implemented by the specific metadata version we are analyzing (ptr == 0, count == 0)
// Skip metadataUsages because it is calculated incorrectly by IL2CPP and the count is wrong
if (foundData.count > 0 && foundData.count != usages.Count) {
// Aggregate uses the first value for 'next' as the seed for 'nearest' unless we specify a starting seed
foundData.count = metaCounts.Aggregate(0, (nearest, next) => next - foundData.count > nearest - foundData.count && next - foundData.count <= 0? next : nearest);
metaCounts = metaCounts.Where(c => c != foundData.count).ToList();
}
// Set item via ref
foundItem = foundData;
// If we just found the Il2CppTypes data, prune the pointer list to the correct length
if (foundItem == types && typesPtrs.Count != foundData.count)
typesPtrs = typesPtrs.Take(foundData.count).ToList();
UpdateProgress(foundData.count);
}
#region Debugging validation checks
#if false
// Used on non-obfuscated binaries during development to confirm the output is correct
if (types.ptr != MetadataRegistration.ptypes)
throw new Exception("Il2CppType** incorrect");
if (genericInsts.ptr != MetadataRegistration.genericInsts)
throw new Exception("Il2CppGenericInst** incorrect");
if (methodSpecs.ptr != MetadataRegistration.methodSpecs)
throw new Exception("Il2CppMethodSpec* incorrect");
if (genericMethodTable.ptr != MetadataRegistration.genericMethodTable)
throw new Exception("Il2CppGenericMethodFunctionsDefinitions* incorrect");
if (metadataUsages.ptr != MetadataRegistration.metadataUsages)
throw new Exception("Metadata usages pointer incorrect");
if (fieldOffsets.ptr != MetadataRegistration.pfieldOffsets)
throw new Exception("Field offsets pointer incorrect");
if (types.count != MetadataRegistration.typesCount)
throw new Exception("Count of Il2CppType* incorrect");
if (genericInsts.count != MetadataRegistration.genericInstsCount)
throw new Exception("Count of Il2CppGenericInst* incorrect");
if (methodSpecs.count != MetadataRegistration.methodSpecsCount)
throw new Exception("Count of Il2CppMethodSpec incorrect");
if (genericMethodTable.count != MetadataRegistration.genericMethodTableCount)
throw new Exception("Count of Il2CppGenericMethodFunctionsDefinitions");
if (metadataUsages.count != usages.Count)
throw new Exception("Count of metadata usages incorrect");
if (fieldOffsets.count != MetadataRegistration.fieldOffsetsCount)
throw new Exception("Count of field offsets incorrect");
#endif
#endregion
// Only update if we found everything
// On failure, Il2CppBinary will throw a NotSupportedException for us
if (types.count == -1 || genericInsts.count == -1 || methodSpecs.count == -1
|| genericMethodTable.count == -1 || metadataUsages.count == -1 || fieldOffsets.count == -1)
return;
// Perform substitution
CodeRegistration.genericMethodPointers = genericMethodPointers.Key;
CodeRegistration.genericMethodPointersCount = (ulong) genericMethodPointers.Value;
CodeRegistration.customAttributeGenerators = customAttributeGenerators.Key;
CodeRegistration.customAttributeCount = customAttributeGenerators.Value;
CodeRegistration.invokerPointers = invokerPointers.Key;
CodeRegistration.invokerPointersCount = (ulong) invokerPointers.Value;
CodeRegistration.pmethodPointers = methodPointers.Key;
CodeRegistration.methodPointersCount = (ulong) methodPointers.Value;
// Zero out any unprocessed items
CodeRegistration.reversePInvokeWrapperCount = 0;
CodeRegistration.reversePInvokeWrappers = 0;
CodeRegistration.delegateWrappersFromManagedToNativeCount = 0;
CodeRegistration.delegateWrappersFromManagedToNative = 0;
CodeRegistration.marshalingFunctionsCount = 0;
CodeRegistration.marshalingFunctions = 0;
CodeRegistration.ccwMarshalingFunctionsCount = 0;
CodeRegistration.ccwMarshalingFunctions = 0;
CodeRegistration.unresolvedVirtualCallCount = 0;
CodeRegistration.unresolvedVirtualCallPointers = 0;
CodeRegistration.interopDataCount = 0;
CodeRegistration.interopData = 0;
CodeRegistration.guidCount = 0;
CodeRegistration.guids = 0;
CodeRegistration.windowsRuntimeFactoryCount = 0;
CodeRegistration.windowsRuntimeFactoryTable = 0;
CodeRegistration.codeGenModulesCount = 0;
CodeRegistration.pcodeGenModules = 0;
// Perform substitution
MetadataRegistration.ptypes = types.ptr;
MetadataRegistration.typesCount = types.count;
MetadataRegistration.genericInsts = genericInsts.ptr;
MetadataRegistration.genericInstsCount = genericInsts.count;
MetadataRegistration.methodSpecs = methodSpecs.ptr;
MetadataRegistration.methodSpecsCount = methodSpecs.count;
MetadataRegistration.genericMethodTable = genericMethodTable.ptr;
MetadataRegistration.genericMethodTableCount = genericMethodTable.count;
MetadataRegistration.metadataUsages = metadataUsages.ptr;
MetadataRegistration.metadataUsagesCount = (ulong) metadataUsages.count;
MetadataRegistration.pfieldOffsets = fieldOffsets.ptr;
MetadataRegistration.fieldOffsetsCount = fieldOffsets.count;
// Zero out any unprocessed items
MetadataRegistration.typeDefinitionsSizesCount = 0;
MetadataRegistration.typeDefinitionsSizes = 0;
MetadataRegistration.genericClassesCount = 0;
MetadataRegistration.genericClasses = 0;
MetadataRegistration.methodReferencesCount = 0;
MetadataRegistration.methodReferences = 0;
// Write changes to stream
Image.WriteObject(Image.MapVATR(CodeRegistrationPointer), CodeRegistration);
Image.WriteObject(Image.MapVATR(MetadataRegistrationPointer), MetadataRegistration);
isModified = true;
StatusUpdate("Analyzing IL2CPP image");
}
}
}