167 lines
5.1 KiB
C#
167 lines
5.1 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.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<TypeDefinition> structToOwner = new TypeDefinitionDict<TypeDefinition>();
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Dictionary<int, bool> oldFieldToken = new Dictionary<int, bool>();
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public List<TypeDefinition> FieldStructs {
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get {
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var list = new List<TypeDefinition>(structToOwner.Count);
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foreach (var structType in structToOwner.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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var ownerType = kv.Value;
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structToOwner.add(structType, ownerType);
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for (int i = 0; i < ownerType.Fields.Count; i++) {
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if (DotNetUtils.getType(module, ownerType.Fields[i].FieldType) != structType)
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continue;
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oldFieldToken[ownerType.Fields[i].MetadataToken.ToInt32()] = true;
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ownerType.Fields.RemoveAt(i);
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break;
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}
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var structTypeFields = new List<FieldDefinition>(structType.Fields);
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structType.Fields.Clear();
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foreach (var field in structTypeFields)
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ownerType.Fields.Add(field);
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// Add a field so peverify won't complain if this type isn't removed
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var newField = new FieldDefinition("a", FieldAttributes.Public, module.TypeSystem.Byte);
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newField.MetadataToken = DotNetUtils.nextFieldToken();
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structType.Fields.Add(newField);
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}
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}
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Dictionary<TypeDefinition, TypeDefinition> getMovedTypes() {
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var fieldTypeToTypes = new Dictionary<TypeDefinition, List<TypeDefinition>>();
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foreach (var type in module.GetTypes()) {
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foreach (var field in type.Fields) {
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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 (hasNonStaticMethods(fieldType))
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continue;
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List<TypeDefinition> list;
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if (!fieldTypeToTypes.TryGetValue(fieldType, out list))
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fieldTypeToTypes[fieldType] = list = new List<TypeDefinition>();
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list.Add(type);
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}
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}
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var candidates = new Dictionary<TypeDefinition, TypeDefinition>();
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foreach (var kv in fieldTypeToTypes) {
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if (kv.Value.Count != 1)
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continue;
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candidates[kv.Key] = kv.Value[0];
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}
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foreach (var type in module.GetTypes()) {
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foreach (var field in type.Fields) {
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if (field.DeclaringType != type)
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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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void removeType(Dictionary<TypeDefinition, 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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public void deobfuscate(Blocks blocks) {
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foreach (var block in blocks.MethodBlocks.getAllBlocks()) {
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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 field = instr.Operand as FieldReference;
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if (field == null)
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continue;
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if (!oldFieldToken.ContainsKey(field.MetadataToken.ToInt32()))
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continue;
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instrs.RemoveAt(i);
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}
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}
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}
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}
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}
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