389 lines
22 KiB
C#
389 lines
22 KiB
C#
/*
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Copyright 2020 Katy Coe - http://www.djkaty.com - https://github.com/djkaty
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All rights reserved.
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*/
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Linq;
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using System.Reflection;
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using System.Text;
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using System.Threading;
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namespace Il2CppInspector
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{
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// Some IL2CPP applications obfuscate the order of fields in Il2CppCodeRegistration and Il2CppMetadataRegistration
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// specifically to defeat IL2CPP reverse engineering tools. We make an imperfect attempt to defeat this below
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// by re-arranging the fields back into their original order. This can be greatly improved and much more deeply analyzed.
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// Devs: Please don't burn development resources on obfuscation. It's a waste of your time and mine. Spend it making good games instead.
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partial class Il2CppBinary
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{
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// Loads all the pointers and counts for the specified IL2CPP metadata type regardless of version or word size into two arrays
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// Sorts the pointers and calculates the maximum number of words between each, constrained by the highest count in the IL2CPP metadata type
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// and by the end of the nearest section in the image.
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// Returns an array of the pointers in sorted order and an array of maximum word counts with corresponding indexes
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private (List<ulong> ptrs, List<int> counts) preparePointerList(Type type, ulong typePtr, IEnumerable<Section> sections) {
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// Get number of pointer/count pairs in each structure
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var itemsCount = Metadata.Sizeof(type, Image.Version, Image.Bits / 8) / (Image.Bits / 8) / 2;
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// Read pointers and counts as two lists
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var itemArray = Image.ReadMappedArray<ulong>(typePtr, itemsCount * 2);
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var itemPtrs = Enumerable.Range(0, itemArray.Length / 2).Select(i => itemArray[i*2 + 1]).ToList();
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var itemCounts = Enumerable.Range(0, itemArray.Length / 2).Select(i => (int) itemArray[i*2]).ToList();
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// Get maximum count between each pair of pointers
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// None of the maximums should be higher than the maximum count specified in the struct
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// Rule out zero pointers for no longer used fields (eg. customAttributeGenerators >=27)
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var itemMaxCount = itemCounts.Max();
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var itemPtrsOrdered = itemPtrs.Where(p => p != 0).OrderBy(p => p).ToList();
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var itemCountLimits = itemPtrsOrdered
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.Zip(itemPtrsOrdered.Skip(1), (a, b) => Math.Min((int) (b - a) / (Image.Bits / 8), itemMaxCount))
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.Append(itemMaxCount)
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.ToList();
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// Prevent a pointer list from overrunning the end of a section
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for (var i = 0; i < itemPtrsOrdered.Count; i++) {
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var section = sections.FirstOrDefault(s => s.VirtualStart <= itemPtrsOrdered[i] && s.VirtualEnd >= itemPtrsOrdered[i]);
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if (section != null) {
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var maxSize = (int) (section.VirtualEnd + 1 - itemPtrsOrdered[i]) / (Image.Bits / 8);
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itemCountLimits[i] = Math.Min(itemCountLimits[i], maxSize);
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}
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}
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return (itemPtrsOrdered, itemCountLimits);
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}
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// Reconstruct Il2CppCodeRegistration and Il2CppMetadataRegistration into their original, unobfuscated field order
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private void ReconstructMetadata(Metadata metadata) {
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// If the section table is not available, give up and do nothing
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if (!Image.TryGetSections(out var sections))
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return;
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// Get relevant image sections
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var codeSections = sections.Where(s => s.IsExec);
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var dataSections = sections.Where(s => s.IsData);
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// Fetch and sanitize our pointer and count lists
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var (codePtrsOrdered, codeCountLimits) = preparePointerList(typeof(Il2CppCodeRegistration), CodeRegistrationPointer, dataSections);
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var (metaPtrsOrdered, metaCountLimits) = preparePointerList(typeof(Il2CppMetadataRegistration), MetadataRegistrationPointer, dataSections);
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// Things we need from Il2CppCodeRegistration
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// methodPointers (<=24.1) -> list of function pointers (1st count) (non-sequential)
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// genericMethodPointers -> list of function pointers (first IS zero) (2nd count) (not sequential)
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// customAttributeGenerators (<27) -> list of function pointers (first MAY be zero) (2nd count) (sequential)
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// invokerPointers -> list of function pointers (3rd count) (sequential)
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// codeGenModules (>=24.2) -> list of Il2CppCodeGenModule* // TODO: We only support <=24.1 currently
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// (interopData will probably have 6 sequential pointers since Il2CppInteropData starts with 5 function pointers and a GUID)
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// Let's see how many valid pointers and sequential valid pointers we actually find at each address
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// Scan each pointer address for valid list of function pointers and sort into size order
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// Consider the sequence to be broken if there is a gap over a certain threshold
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var sequenceThreshold = 0x10000;
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var fnPtrs = new SortedDictionary<ulong, int>();
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var seqFnPtrs = new SortedDictionary<ulong, int>();
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for (var i = 0; i < codePtrsOrdered.Count; i++) {
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// Non-sequential valid pointers
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var ptrs = Image.ReadMappedArray<ulong>(codePtrsOrdered[i], codeCountLimits[i]);
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var foundCount = ptrs.TakeWhile(p => codeSections.Any(s => p >= s.VirtualStart && p <= s.VirtualEnd || p == 0)).Count();
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// Prune count of trailing zero pointers
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while (foundCount > 0 && ptrs[foundCount - 1] == 0ul)
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foundCount--;
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fnPtrs.Add(codePtrsOrdered[i], foundCount);
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// Binaries compiled with MSVC (generally PE files) use /OPT:ICF by default (enable ICF) so this won't work.
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// For these binaries, we'll use a different selection strategy below
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if (Image is PEReader)
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continue;
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// Sequential valid pointers (a subset of non-sequential valid pointers)
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foundCount = ptrs.Take(foundCount)
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.Zip(ptrs.Take(foundCount).Skip(1), (a, b) => (a, b))
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.TakeWhile(t => ((long) t.b - (long) t.a >= 0 || t.b == 0)
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&& ((long) t.b - (long) t.a < sequenceThreshold || t.a == 0)
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// Disallow two zero pointers in a row
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&& (t.a != 0 || t.b != 0))
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.Count() + 1;
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// Prune count of trailing zero pointers
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while (foundCount > 0 && ptrs[foundCount - 1] == 0ul)
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foundCount--;
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seqFnPtrs.Add(codePtrsOrdered[i], foundCount);
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}
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KeyValuePair<ulong, int> methodPointers, genericMethodPointers, customAttributeGenerators, invokerPointers;
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// Solution without ICF
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if (!(Image is PEReader)) {
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// The two largest sequential groups are customAttributeGenerators and invokerPointers
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var seqLongest = seqFnPtrs.OrderByDescending(kv => kv.Value).Take(2).ToList();
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(customAttributeGenerators, invokerPointers) = (seqLongest[0], seqLongest[1]);
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// For >=27, customAttributeGenerators is zero and so the largest group is invokerPointers
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if (Image.Version >= 27) {
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invokerPointers = customAttributeGenerators;
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customAttributeGenerators = new KeyValuePair<ulong, int>(0ul, 0);
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}
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// After removing these from the non-sequential list, the largest groups are methodPointers and genericMethodPointers
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var longest = fnPtrs.Except(seqLongest).OrderByDescending(kv => kv.Value).Take(2).ToList();
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(methodPointers, genericMethodPointers) = (longest[0], longest[1]);
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// For >=24.2, methodPointers is zero and so the largest group is genericMethodPointers
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if (Image.Version >= 24.2) {
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genericMethodPointers = methodPointers;
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methodPointers = new KeyValuePair<ulong, int>(0ul, 0);
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}
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// Prune genericMethodPointers at 2nd zero (first pointer is always zero)
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var gmPtr = Image.ReadMappedArray<ulong>(genericMethodPointers.Key, genericMethodPointers.Value);
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var gmZero = Array.IndexOf(gmPtr, 0ul, 1);
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if (gmZero != -1)
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genericMethodPointers = new KeyValuePair<ulong, int>(genericMethodPointers.Key, gmZero);
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}
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// Solution with ICF
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else {
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// Take and remove the first item and assume it's methodPointers for <=24.1, otherwise set to zero
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var orderedPtrs = fnPtrs.OrderByDescending(kv => kv.Value).ToList();
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if (Image.Version <= 24.1) {
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methodPointers = orderedPtrs[0];
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orderedPtrs.RemoveAt(0);
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} else
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methodPointers = new KeyValuePair<ulong, int>(0ul, 0);
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// Assume this order is right most of the time
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// TODO: generic and custom attribute might be the wrong way round (eg. #102)
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(genericMethodPointers, customAttributeGenerators, invokerPointers) = (orderedPtrs[0], orderedPtrs[1], orderedPtrs[2]);
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// customAttributeGenerators is removed in metadata >=27
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if (Image.Version >= 27) {
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invokerPointers = customAttributeGenerators;
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customAttributeGenerators = new KeyValuePair<ulong, int>(0ul, 0);
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}
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}
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#region Debugging validation checks
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#if DEBUG
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// Used on non-obfuscated binaries during development to confirm the output is correct
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if (methodPointers.Key != CodeRegistration.pmethodPointers)
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throw new Exception("Method Pointers incorrect");
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if (invokerPointers.Key != CodeRegistration.invokerPointers)
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throw new Exception("Invoker Pointers incorrect");
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if (customAttributeGenerators.Key != CodeRegistration.customAttributeGenerators)
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throw new Exception("Custom attribute generators incorrect");
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if (genericMethodPointers.Key != CodeRegistration.genericMethodPointers)
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throw new Exception("Generic method pointers incorrect");
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if (methodPointers.Value != (int) CodeRegistration.methodPointersCount)
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throw new Exception("Count of Method Pointers incorrect");
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if (invokerPointers.Value != (int) CodeRegistration.invokerPointersCount)
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throw new Exception("Count of Invoker Pointers incorrect");
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if (customAttributeGenerators.Value != (int) CodeRegistration.customAttributeCount)
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throw new Exception("Count of Custom attribute generators incorrect");
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if (genericMethodPointers.Value != (int) CodeRegistration.genericMethodPointersCount)
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throw new Exception("Count of Generic method pointers incorrect");
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#endif
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#endregion
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// Perform substitution
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CodeRegistration.genericMethodPointers = genericMethodPointers.Key;
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CodeRegistration.genericMethodPointersCount = (ulong) genericMethodPointers.Value;
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CodeRegistration.customAttributeGenerators = customAttributeGenerators.Key;
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CodeRegistration.customAttributeCount = customAttributeGenerators.Value;
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CodeRegistration.invokerPointers = invokerPointers.Key;
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CodeRegistration.invokerPointersCount = (ulong) invokerPointers.Value;
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CodeRegistration.pmethodPointers = methodPointers.Key;
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CodeRegistration.methodPointersCount = (ulong) methodPointers.Value;
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// Force CodeRegistration to pass validation in Il2CppBinary.Configure()
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CodeRegistration.reversePInvokeWrapperCount = 0;
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CodeRegistration.unresolvedVirtualCallCount = 0;
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CodeRegistration.interopDataCount = 0;
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// Things we need from Il2CppMetadataRegistration
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// genericInsts -> list of Il2CppGenericInst* (argc is count of Il2CppType* at data pointer argv; datapoint = GenericParameterIndex)
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// genericMethodTable -> list of Il2CppGenericMethodFunctionsDefinitions (genericMethodIndex, methodIndex, invokerIndex)
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// types -> list of Il2CppType*
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// methodSpecs -> list of Il2CppMethodSpec
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// methodReferences (<=16) -> list of uint
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// fieldOffsets (fieldOffsetsArePointers) -> either a list of data pointers (some zero, some VAs not mappable) to list of uints, or a list of uints
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// metadataUsages (>=19, <27) -> list of unmappable data pointers
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// We can only perform this re-ordering if we can refer to a loaded global-metadata.dat
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if (metadata == null)
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return;
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// Read in all the required data once since we'll be using nested loops
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var metaPtrData = new List<(ulong, int, ulong[], ulong[], int, int, int)>();
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for (var i = 0; i < metaPtrsOrdered.Count; i++) {
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// Pointers in this list
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var ptrs = Image.ReadMappedArray<ulong>(metaPtrsOrdered[i], metaCountLimits[i]);
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// foundCount and foundMappableCount will generally be the same below
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// except in PE files where data and bss can overlap in our interpretation of the sections
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// First set of pointers that point to a data section virtual address
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var foundCount = ptrs.TakeWhile(p => dataSections.Any(s => p >= s.VirtualStart && p <= s.VirtualEnd)).Count();
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// First set of pointers that can be mapped anywhere into the image
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var foundMappableCount = ptrs.TakeWhile(p => Image.TryMapVATR(p, out _)).Count();
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// First set of pointers that can be mapped into a data section in the image
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var ptrsMappableData = ptrs.Take(foundMappableCount)
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.TakeWhile(p => dataSections.Any(s => Image.MapVATR(p) >= s.ImageStart && Image.MapVATR(p) <= s.ImageEnd))
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.ToArray();
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var foundMappableDataCount = ptrsMappableData.Length;
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metaPtrData.Add((metaPtrsOrdered[i], metaCountLimits[i], ptrs, ptrsMappableData, foundCount, foundMappableCount, foundMappableDataCount));
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}
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// Items we need to search for
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var types = (ptr: 0ul, count: -1);
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var genericInsts = (ptr: 0ul, count: -1);
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// Intermediary items
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var typesData = new Dictionary<ulong, Il2CppType>();
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var genericInstsCount = 0;
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// Determine what each pointer is
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// We need to do this in a certain order because validating some items relies on earlier items
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while (metaPtrData.Any()) {
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var foundTarget = 0ul;
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// We loop repeatedly through every set of data looking for our next target item,
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// remove the matching set from the list and then repeat the outer while loop
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// until there is nothing left to find
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foreach (var (ptr, count, ptrs, ptrsMappableData, foundCount, foundMappableCount, foundMappableDataCount) in metaPtrData) {
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// Test for Il2CppType**
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// ---------------------
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if (types.ptr == 0) {
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// We don't ever expect there to be less than 0x1000 types
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if (foundMappableDataCount >= 0x1000) {
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// This statement is quite slow. We could speed it up with a two-stage approach
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var testItems = Image.ReadMappedObjectPointerArray<Il2CppType>(ptr, foundMappableDataCount);
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var foundItems = 0;
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foreach (var item in testItems) {
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// TODO: v27 will fail this because of the bit shifting in Il2CppType.bits
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if (item.num_mods != 0)
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break;
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if (!Enum.IsDefined(typeof(Il2CppTypeEnum), item.type))
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break;
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if (item.type == Il2CppTypeEnum.IL2CPP_TYPE_END)
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break;
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// Test datapoint
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if (item.type switch {
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var t when (t is Il2CppTypeEnum.IL2CPP_TYPE_VALUETYPE || t is Il2CppTypeEnum.IL2CPP_TYPE_CLASS)
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&& item.datapoint >= (ulong) metadata.Types.Length => false,
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var t when (t is Il2CppTypeEnum.IL2CPP_TYPE_VAR || t is Il2CppTypeEnum.IL2CPP_TYPE_MVAR)
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&& item.datapoint >= (ulong) metadata.GenericParameters.Length => false,
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var t when (t is Il2CppTypeEnum.IL2CPP_TYPE_PTR || t is Il2CppTypeEnum.IL2CPP_TYPE_SZARRAY)
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&& !ptrsMappableData.Contains(item.datapoint) => false,
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// Untested cases, we could add more here (IL2CPP_TYPE_ARRAY, IL2CPP_TYPE_GENERICINST)
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_ => true
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})
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foundItems++;
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else
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break;
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}
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if (foundItems >= 0x1000) {
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types = (ptr, foundItems);
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typesData = ptrs.Take(foundItems)
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.Zip(testItems.Take(foundItems),(p, t) => (Ptr: p, Type: t))
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.ToDictionary(kv => kv.Ptr, kv => kv.Type);
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foundTarget = ptr;
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break;
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}
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}
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}
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// Test for Il2CppGenericInst**
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// ----------------------------
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else if (genericInsts.ptr == 0) {
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var testItems = Image.ReadMappedObjectPointerArray<Il2CppGenericInst>(ptr, foundMappableDataCount);
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var foundItems = 0;
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foreach (var item in testItems) {
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// Let's pray no generic type has more than 32 type parameters
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if (item.type_argc > 32)
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break;
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// All the generic type paramters must be in the total list of types,
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// ie. typePtrs must be a subset of typesData.Keys
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try {
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var typePtrs = Image.ReadMappedArray<ulong>(item.type_argv, (int) item.type_argc);
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if (typePtrs.Except(typesData.Keys).Any())
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break;
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// Pointers were invalid
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} catch (InvalidOperationException) {
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break;
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}
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foundItems++;
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}
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if (foundItems >= 0x100) {
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genericInsts = (ptr, foundItems);
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genericInstsCount = foundItems;
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foundTarget = ptr;
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break;
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}
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}
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}
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// Successfully found the item we were looking for; remove it from the list
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if (foundTarget != 0ul)
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metaPtrData = metaPtrData.Where(m => foundTarget != m.Item1).ToList();
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// We didn't find anything - break to avoid an infinite loop
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else
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break;
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}
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#region Debugging validation checks
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#if DEBUG
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// Used on non-obfuscated binaries during development to confirm the output is correct
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if (types.ptr != MetadataRegistration.ptypes)
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throw new Exception("Il2CppType** incorrect");
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if (genericInsts.ptr != MetadataRegistration.genericInsts)
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throw new Exception("Il2CppGenericInst** incorrect");
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if (types.count != MetadataRegistration.typesCount)
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throw new Exception("Count of Il2CppType* incorrect");
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if (genericInsts.count != MetadataRegistration.genericInstsCount)
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throw new Exception("Count of Il2CppGenericInst* incorrect");
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#endif
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#endregion
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// Perform substitution
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MetadataRegistration.ptypes = types.ptr;
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MetadataRegistration.typesCount = types.count;
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MetadataRegistration.genericInsts = genericInsts.ptr;
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MetadataRegistration.genericInstsCount = genericInsts.count;
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// Force MetadataRegistration to pass validation in Il2CppBinary.Configure()
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MetadataRegistration.typeDefinitionsSizesCount = 0;
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MetadataRegistration.genericClassesCount = MetadataRegistration.genericInstsCount + 1;
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MetadataRegistration.genericMethodTableCount = MetadataRegistration.genericInstsCount + 1;
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}
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}
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} |