238 lines
7.6 KiB
C#
238 lines
7.6 KiB
C#
/*
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Copyright (C) 2011-2012 de4dot@gmail.com
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This file is part of de4dot.
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de4dot is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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de4dot is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with de4dot. If not, see <http://www.gnu.org/licenses/>.
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*/
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using System;
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using System.Collections.Generic;
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using Mono.Cecil;
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using Mono.Cecil.Cil;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators.DeepSea {
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// DS 4.x can move fields from a class to a struct. This class restores the fields.
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class FieldsRestorer {
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ModuleDefinition module;
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TypeDefinitionDict<List<TypeDefinition>> structToOwners = new TypeDefinitionDict<List<TypeDefinition>>();
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FieldDefinitionAndDeclaringTypeDict<bool> structFieldsToFix = new FieldDefinitionAndDeclaringTypeDict<bool>();
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TypeDefinitionDict<FieldDefinitionAndDeclaringTypeDict<FieldDefinition>> typeToFieldsDict = new TypeDefinitionDict<FieldDefinitionAndDeclaringTypeDict<FieldDefinition>>();
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public List<TypeDefinition> FieldStructs {
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get {
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var list = new List<TypeDefinition>(structToOwners.Count);
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foreach (var structType in structToOwners.getKeys()) {
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if (structType.Methods.Count != 0)
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continue;
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list.Add(structType);
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}
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return list;
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}
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}
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public FieldsRestorer(ModuleDefinition module) {
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this.module = module;
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}
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public void initialize() {
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foreach (var kv in getMovedTypes()) {
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var structType = kv.Key;
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structToOwners.add(structType, kv.Value);
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foreach (var ownerType in kv.Value) {
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foreach (var ownerField in ownerType.Fields) {
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if (DotNetUtils.getType(module, ownerField.FieldType) != structType)
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continue;
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structFieldsToFix.add(ownerField, true);
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break;
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}
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var fieldsDict = new FieldDefinitionAndDeclaringTypeDict<FieldDefinition>();
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typeToFieldsDict.add(ownerType, fieldsDict);
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foreach (var structField in structType.Fields) {
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var newField = DotNetUtils.createFieldDefinition(structField.Name, structField.Attributes, structField.FieldType);
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ownerType.Fields.Add(newField);
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fieldsDict.add(structField, newField);
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}
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}
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}
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}
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Dictionary<TypeDefinition, List<TypeDefinition>> getMovedTypes() {
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var candidates = new Dictionary<TypeDefinition, List<TypeDefinition>>();
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var typeToStruct = new Dictionary<TypeDefinition, TypeDefinition>();
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foreach (var type in module.GetTypes()) {
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foreach (var field in getPossibleFields(type)) {
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var fieldType = DotNetUtils.getType(module, field.FieldType);
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if (fieldType == null || !fieldType.IsValueType)
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continue;
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if ((fieldType.Attributes & ~TypeAttributes.Sealed) != TypeAttributes.NestedAssembly)
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continue;
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if (fieldType.NestedTypes.Count > 0)
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continue;
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if (fieldType.GenericParameters.Count > 0)
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continue;
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if (fieldType.Fields.Count == 0)
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continue;
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if (fieldType.HasEvents || fieldType.HasProperties || fieldType.HasInterfaces)
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continue;
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if (hasNonStaticMethods(fieldType))
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continue;
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if (hasStaticFields(fieldType))
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continue;
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List<TypeDefinition> list;
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if (!candidates.TryGetValue(fieldType, out list))
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candidates[fieldType] = list = new List<TypeDefinition>();
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list.Add(type);
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typeToStruct[type] = fieldType;
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break;
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}
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}
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foreach (var type in module.GetTypes()) {
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TypeDefinition structType;
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typeToStruct.TryGetValue(type, out structType);
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foreach (var field in type.Fields) {
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if (field.IsStatic || field.FieldType != structType)
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removeType(candidates, field.FieldType);
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}
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foreach (var method in type.Methods) {
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removeType(candidates, method.MethodReturnType.ReturnType);
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foreach (var parameter in method.Parameters)
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removeType(candidates, parameter.ParameterType);
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if (method.Body != null) {
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foreach (var local in method.Body.Variables)
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removeType(candidates, local.VariableType);
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}
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}
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}
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return candidates;
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}
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IEnumerable<FieldDefinition> getPossibleFields(TypeDefinition type) {
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var typeToFields = new TypeDefinitionDict<List<FieldDefinition>>();
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foreach (var field in type.Fields) {
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if (field.Attributes != FieldAttributes.Private)
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continue;
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var fieldType = DotNetUtils.getType(module, field.FieldType);
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if (fieldType == null || !fieldType.IsValueType)
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continue;
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var list = typeToFields.find(fieldType);
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if (list == null)
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typeToFields.add(fieldType, list = new List<FieldDefinition>());
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list.Add(field);
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}
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foreach (var list in typeToFields.getValues()) {
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if (list.Count == 1)
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yield return list[0];
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}
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}
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void removeType(Dictionary<TypeDefinition, List<TypeDefinition>> candidates, TypeReference type) {
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var typeDef = DotNetUtils.getType(module, type);
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if (typeDef == null)
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return;
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candidates.Remove(typeDef);
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}
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static bool hasNonStaticMethods(TypeDefinition type) {
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foreach (var method in type.Methods) {
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if (method.Name == ".cctor")
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continue;
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if (!method.IsStatic)
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return true;
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if (method.GenericParameters.Count > 0)
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return true;
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if (method.Body == null)
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return true;
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if (method.HasPInvokeInfo || method.PInvokeInfo != null)
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return true;
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}
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return false;
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}
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static bool hasStaticFields(TypeDefinition type) {
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foreach (var field in type.Fields) {
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if (field.IsStatic)
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return true;
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}
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return false;
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}
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public void deobfuscate(Blocks blocks) {
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var instrsToRemove = new List<int>();
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foreach (var block in blocks.MethodBlocks.getAllBlocks()) {
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instrsToRemove.Clear();
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var instrs = block.Instructions;
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for (int i = instrs.Count - 1; i >= 0; i--) {
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var instr = instrs[i];
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if (instr.OpCode.Code != Code.Ldflda)
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continue;
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var structField = instr.Operand as FieldReference;
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if (structField == null || !structFieldsToFix.find(structField))
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continue;
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var ldStFld = instrs[findLdStFieldIndex(instrs, i + 1)];
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ldStFld.Operand = getNewField(structField, ldStFld.Operand as FieldReference);
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instrsToRemove.Add(i);
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}
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if (instrsToRemove.Count > 0)
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block.remove(instrsToRemove);
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}
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}
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FieldDefinition getNewField(FieldReference structField, FieldReference oldFieldRef) {
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var fieldsDict = typeToFieldsDict.find(structField.DeclaringType);
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if (fieldsDict == null)
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throw new ApplicationException("Could not find structField declaringType");
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var newField = fieldsDict.find(oldFieldRef);
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if (newField == null)
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throw new ApplicationException("Could not find new field");
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return newField;
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}
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static int findLdStFieldIndex(IList<Instr> instrs, int index) {
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int stack = 0;
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for (int i = index; i < instrs.Count; i++) {
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var instr = instrs[i];
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if (stack == 0 && (instr.OpCode.Code == Code.Ldfld || instr.OpCode.Code == Code.Ldflda))
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return i;
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if (stack == 1 && instr.OpCode.Code == Code.Stfld)
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return i;
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int pushes, pops;
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DotNetUtils.calculateStackUsage(instr.Instruction, false, out pushes, out pops);
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stack -= pops;
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if (stack < 0)
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break;
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stack += pushes;
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}
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throw new ApplicationException("Could not find ldfld/stfld");
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}
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public void cleanUp() {
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foreach (var field in structFieldsToFix.getKeys())
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field.DeclaringType.Fields.Remove(field);
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}
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}
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}
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