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Update fields restorer since 2+ types can share same struct

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This commit is contained in:
de4dot 2012-01-28 23:44:41 +01:00
parent ef3b610c92
commit 26a3e14d2c
2 changed files with 114 additions and 41 deletions
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2
de4dot.code/deobfuscators/DeepSea/Deobfuscator.cs
View File

@ -231,6 +231,8 @@ done:
}
public override void deobfuscateEnd() {
if (options.RestoreFields)
fieldsRestorer.cleanUp();
removeInlinedMethods();
if (options.RestoreFields)

153
de4dot.code/deobfuscators/DeepSea/FieldsRestorer.cs
View File

@ -17,6 +17,7 @@
along with de4dot. If not, see <http://www.gnu.org/licenses/>.
*/
using System;
using System.Collections.Generic;
using Mono.Cecil;
using Mono.Cecil.Cil;
@ -26,13 +27,14 @@ namespace de4dot.code.deobfuscators.DeepSea {
// DS 4.x can move fields from a class to a struct. This class restores the fields.
class FieldsRestorer {
ModuleDefinition module;
TypeDefinitionDict<TypeDefinition> structToOwner = new TypeDefinitionDict<TypeDefinition>();
Dictionary<int, bool> oldFieldToken = new Dictionary<int, bool>();
TypeDefinitionDict<List<TypeDefinition>> structToOwners = new TypeDefinitionDict<List<TypeDefinition>>();
FieldDefinitionAndDeclaringTypeDict<bool> structFieldsToFix = new FieldDefinitionAndDeclaringTypeDict<bool>();
TypeDefinitionDict<FieldDefinitionAndDeclaringTypeDict<FieldDefinition>> typeToFieldsDict = new TypeDefinitionDict<FieldDefinitionAndDeclaringTypeDict<FieldDefinition>>();
public List<TypeDefinition> FieldStructs {
get {
var list = new List<TypeDefinition>(structToOwner.Count);
foreach (var structType in structToOwner.getKeys()) {
var list = new List<TypeDefinition>(structToOwners.Count);
foreach (var structType in structToOwners.getKeys()) {
if (structType.Methods.Count != 0)
continue;
@ -49,33 +51,32 @@ namespace de4dot.code.deobfuscators.DeepSea {
public void initialize() {
foreach (var kv in getMovedTypes()) {
var structType = kv.Key;
var ownerType = kv.Value;
structToOwner.add(structType, ownerType);
structToOwners.add(structType, kv.Value);
for (int i = 0; i < ownerType.Fields.Count; i++) {
if (DotNetUtils.getType(module, ownerType.Fields[i].FieldType) != structType)
continue;
oldFieldToken[ownerType.Fields[i].MetadataToken.ToInt32()] = true;
ownerType.Fields.RemoveAt(i);
break;
foreach (var ownerType in kv.Value) {
foreach (var ownerField in ownerType.Fields) {
if (DotNetUtils.getType(module, ownerField.FieldType) != structType)
continue;
structFieldsToFix.add(ownerField, true);
break;
}
var fieldsDict = new FieldDefinitionAndDeclaringTypeDict<FieldDefinition>();
typeToFieldsDict.add(ownerType, fieldsDict);
foreach (var structField in structType.Fields) {
var newField = DotNetUtils.createFieldDefinition(structField.Name, structField.Attributes, structField.FieldType);
ownerType.Fields.Add(newField);
fieldsDict.add(structField, newField);
}
}
var structTypeFields = new List<FieldDefinition>(structType.Fields);
structType.Fields.Clear();
foreach (var field in structTypeFields)
ownerType.Fields.Add(field);
// Add a field so peverify won't complain if this type isn't removed
var newField = new FieldDefinition("a", FieldAttributes.Public, module.TypeSystem.Byte);
newField.MetadataToken = DotNetUtils.nextFieldToken();
structType.Fields.Add(newField);
}
}
Dictionary<TypeDefinition, TypeDefinition> getMovedTypes() {
var fieldTypeToTypes = new Dictionary<TypeDefinition, List<TypeDefinition>>();
Dictionary<TypeDefinition, List<TypeDefinition>> getMovedTypes() {
var candidates = new Dictionary<TypeDefinition, List<TypeDefinition>>();
var typeToStruct = new Dictionary<TypeDefinition, TypeDefinition>();
foreach (var type in module.GetTypes()) {
foreach (var field in type.Fields) {
foreach (var field in getPossibleFields(type)) {
var fieldType = DotNetUtils.getType(module, field.FieldType);
if (fieldType == null || !fieldType.IsValueType)
continue;
@ -87,26 +88,28 @@ namespace de4dot.code.deobfuscators.DeepSea {
continue;
if (fieldType.Fields.Count == 0)
continue;
if (fieldType.HasEvents || fieldType.HasProperties || fieldType.HasInterfaces)
continue;
if (hasNonStaticMethods(fieldType))
continue;
if (hasStaticFields(fieldType))
continue;
List<TypeDefinition> list;
if (!fieldTypeToTypes.TryGetValue(fieldType, out list))
fieldTypeToTypes[fieldType] = list = new List<TypeDefinition>();
if (!candidates.TryGetValue(fieldType, out list))
candidates[fieldType] = list = new List<TypeDefinition>();
list.Add(type);
typeToStruct[type] = fieldType;
break;
}
}
var candidates = new Dictionary<TypeDefinition, TypeDefinition>();
foreach (var kv in fieldTypeToTypes) {
if (kv.Value.Count != 1)
continue;
candidates[kv.Key] = kv.Value[0];
}
foreach (var type in module.GetTypes()) {
TypeDefinition structType;
typeToStruct.TryGetValue(type, out structType);
foreach (var field in type.Fields) {
if (field.DeclaringType != type)
if (field.IsStatic || field.FieldType != structType)
removeType(candidates, field.FieldType);
}
foreach (var method in type.Methods) {
@ -123,7 +126,27 @@ namespace de4dot.code.deobfuscators.DeepSea {
return candidates;
}
void removeType(Dictionary<TypeDefinition, TypeDefinition> candidates, TypeReference type) {
IEnumerable<FieldDefinition> getPossibleFields(TypeDefinition type) {
var typeToFields = new TypeDefinitionDict<List<FieldDefinition>>();
foreach (var field in type.Fields) {
if (field.Attributes != FieldAttributes.Private)
continue;
var fieldType = DotNetUtils.getType(module, field.FieldType);
if (fieldType == null || !fieldType.IsValueType)
continue;
var list = typeToFields.find(fieldType);
if (list == null)
typeToFields.add(fieldType, list = new List<FieldDefinition>());
list.Add(field);
}
foreach (var list in typeToFields.getValues()) {
if (list.Count == 1)
yield return list[0];
}
}
void removeType(Dictionary<TypeDefinition, List<TypeDefinition>> candidates, TypeReference type) {
var typeDef = DotNetUtils.getType(module, type);
if (typeDef == null)
return;
@ -146,21 +169,69 @@ namespace de4dot.code.deobfuscators.DeepSea {
return false;
}
static bool hasStaticFields(TypeDefinition type) {
foreach (var field in type.Fields) {
if (field.IsStatic)
return true;
}
return false;
}
public void deobfuscate(Blocks blocks) {
var instrsToRemove = new List<int>();
foreach (var block in blocks.MethodBlocks.getAllBlocks()) {
instrsToRemove.Clear();
var instrs = block.Instructions;
for (int i = instrs.Count - 1; i >= 0; i--) {
var instr = instrs[i];
if (instr.OpCode.Code != Code.Ldflda)
continue;
var field = instr.Operand as FieldReference;
if (field == null)
var structField = instr.Operand as FieldReference;
if (structField == null || !structFieldsToFix.find(structField))
continue;
if (!oldFieldToken.ContainsKey(field.MetadataToken.ToInt32()))
continue;
instrs.RemoveAt(i);
var ldStFld = instrs[findLdStFieldIndex(instrs, i + 1)];
ldStFld.Operand = getNewField(structField, ldStFld.Operand as FieldReference);
instrsToRemove.Add(i);
}
if (instrsToRemove.Count > 0)
block.remove(instrsToRemove);
}
}
FieldDefinition getNewField(FieldReference structField, FieldReference oldFieldRef) {
var fieldsDict = typeToFieldsDict.find(structField.DeclaringType);
if (fieldsDict == null)
throw new ApplicationException("Could not find structField declaringType");
var newField = fieldsDict.find(oldFieldRef);
if (newField == null)
throw new ApplicationException("Could not find new field");
return newField;
}
static int findLdStFieldIndex(IList<Instr> instrs, int index) {
int stack = 0;
for (int i = index; i < instrs.Count; i++) {
var instr = instrs[i];
if (stack == 0 && (instr.OpCode.Code == Code.Ldfld || instr.OpCode.Code == Code.Ldflda))
return i;
if (stack == 1 && instr.OpCode.Code == Code.Stfld)
return i;
int pushes, pops;
DotNetUtils.calculateStackUsage(instr.Instruction, false, out pushes, out pops);
stack -= pops;
if (stack < 0)
break;
stack += pushes;
}
throw new ApplicationException("Could not find ldfld/stfld");
}
public void cleanUp() {
foreach (var field in structFieldsToFix.getKeys())
field.DeclaringType.Fields.Remove(field);
}
}
}