436 lines
14 KiB
C#
436 lines
14 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 System.IO;
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using dot10.DotNet;
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using dot10.DotNet.Emit;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators.Agile_NET.vm {
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class CsvmToCilMethodConverter {
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IDeobfuscatorContext deobfuscatorContext;
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ModuleDefMD module;
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VmOpCodeHandlerDetector opCodeDetector;
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CilOperandInstructionRestorer operandRestorer = new CilOperandInstructionRestorer();
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public CsvmToCilMethodConverter(IDeobfuscatorContext deobfuscatorContext, ModuleDefMD module, VmOpCodeHandlerDetector opCodeDetector) {
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this.deobfuscatorContext = deobfuscatorContext;
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this.module = module;
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this.opCodeDetector = opCodeDetector;
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}
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public void convert(MethodDef cilMethod, CsvmMethodData csvmMethod) {
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var newInstructions = readInstructions(cilMethod, csvmMethod);
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var newLocals = readLocals(cilMethod, csvmMethod);
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var newExceptions = readExceptions(cilMethod, csvmMethod, newInstructions);
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fixInstructionOperands(newInstructions);
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fixLocals(newInstructions, cilMethod.Body.Variables);
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fixArgs(newInstructions, cilMethod);
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DotNetUtils.restoreBody(cilMethod, newInstructions, newExceptions);
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if (!operandRestorer.restore(cilMethod))
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Logger.w("Failed to restore one or more instruction operands in CSVM method {0:X8}", cilMethod.MDToken.ToInt32());
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restoreConstrainedPrefix(cilMethod);
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}
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void fixLocals(IList<Instruction> instrs, IList<Local> locals) {
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foreach (var instr in instrs) {
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var op = instr.Operand as LocalOperand;
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if (op == null)
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continue;
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updateLocalInstruction(instr, locals[op.local], op.local);
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}
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}
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static void updateLocalInstruction(Instruction instr, Local local, int index) {
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object operand = null;
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OpCode opcode;
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switch (instr.OpCode.Code) {
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case Code.Ldloc_S:
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case Code.Ldloc:
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if (index == 0)
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opcode = OpCodes.Ldloc_0;
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else if (index == 1)
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opcode = OpCodes.Ldloc_1;
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else if (index == 2)
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opcode = OpCodes.Ldloc_2;
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else if (index == 3)
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opcode = OpCodes.Ldloc_3;
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else if (byte.MinValue <= index && index <= byte.MaxValue) {
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opcode = OpCodes.Ldloc_S;
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operand = local;
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}
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else {
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opcode = OpCodes.Ldloc;
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operand = local;
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}
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break;
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case Code.Stloc:
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case Code.Stloc_S:
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if (index == 0)
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opcode = OpCodes.Stloc_0;
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else if (index == 1)
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opcode = OpCodes.Stloc_1;
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else if (index == 2)
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opcode = OpCodes.Stloc_2;
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else if (index == 3)
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opcode = OpCodes.Stloc_3;
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else if (byte.MinValue <= index && index <= byte.MaxValue) {
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opcode = OpCodes.Stloc_S;
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operand = local;
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}
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else {
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opcode = OpCodes.Stloc;
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operand = local;
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}
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break;
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case Code.Ldloca:
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case Code.Ldloca_S:
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if (byte.MinValue <= index && index <= byte.MaxValue) {
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opcode = OpCodes.Ldloca_S;
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operand = local;
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}
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else {
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opcode = OpCodes.Ldloca;
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operand = local;
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}
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break;
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default:
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throw new ApplicationException("Invalid opcode");
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}
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instr.OpCode = opcode;
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instr.Operand = operand;
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}
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void fixArgs(IList<Instruction> instrs, MethodDef method) {
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foreach (var instr in instrs) {
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var op = instr.Operand as ArgOperand;
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if (op == null)
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continue;
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updateArgInstruction(instr, method.Parameters[op.arg], op.arg);
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}
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}
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static void updateArgInstruction(Instruction instr, Parameter arg, int index) {
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switch (instr.OpCode.Code) {
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case Code.Ldarg:
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case Code.Ldarg_S:
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if (index == 0) {
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instr.OpCode = OpCodes.Ldarg_0;
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instr.Operand = null;
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}
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else if (index == 1) {
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instr.OpCode = OpCodes.Ldarg_1;
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instr.Operand = null;
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}
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else if (index == 2) {
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instr.OpCode = OpCodes.Ldarg_2;
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instr.Operand = null;
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}
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else if (index == 3) {
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instr.OpCode = OpCodes.Ldarg_3;
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instr.Operand = null;
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}
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else if (byte.MinValue <= index && index <= byte.MaxValue) {
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instr.OpCode = OpCodes.Ldarg_S;
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instr.Operand = arg;
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}
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else {
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instr.OpCode = OpCodes.Ldarg;
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instr.Operand = arg;
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}
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break;
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case Code.Starg:
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case Code.Starg_S:
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if (byte.MinValue <= index && index <= byte.MaxValue) {
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instr.OpCode = OpCodes.Starg_S;
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instr.Operand = arg;
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}
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else {
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instr.OpCode = OpCodes.Starg;
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instr.Operand = arg;
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}
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break;
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case Code.Ldarga:
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case Code.Ldarga_S:
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if (byte.MinValue <= index && index <= byte.MaxValue) {
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instr.OpCode = OpCodes.Ldarga_S;
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instr.Operand = arg;
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}
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else {
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instr.OpCode = OpCodes.Ldarga;
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instr.Operand = arg;
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}
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break;
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default:
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throw new ApplicationException("Invalid opcode");
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}
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}
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List<Instruction> readInstructions(MethodDef cilMethod, CsvmMethodData csvmMethod) {
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var reader = new BinaryReader(new MemoryStream(csvmMethod.Instructions));
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var instrs = new List<Instruction>();
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uint offset = 0;
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while (reader.BaseStream.Position < reader.BaseStream.Length) {
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int vmOpCode = reader.ReadUInt16();
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var instr = opCodeDetector.Handlers[vmOpCode].Read(reader);
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instr.Offset = offset;
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offset += (uint)getInstructionSize(instr);
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instrs.Add(instr);
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}
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return instrs;
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}
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static int getInstructionSize(Instruction instr) {
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var opcode = instr.OpCode;
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if (opcode == null)
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return 5; // Load store/field
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var op = instr.Operand as SwitchTargetDisplOperand;
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if (op == null)
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return instr.GetSize();
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return instr.OpCode.Size + (op.targetDisplacements.Length + 1) * 4;
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}
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List<Local> readLocals(MethodDef cilMethod, CsvmMethodData csvmMethod) {
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var locals = new List<Local>();
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var reader = new BinaryReader(new MemoryStream(csvmMethod.Locals));
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if (csvmMethod.Locals.Length == 0)
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return locals;
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// v6.0.0.5 sometimes duplicates the last two locals so only check for a negative value.
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int numLocals = reader.ReadInt32();
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if (numLocals < 0)
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throw new ApplicationException("Invalid number of locals");
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for (int i = 0; i < numLocals; i++)
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locals.Add(new Local(readTypeRef(reader)));
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return locals;
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}
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TypeSig readTypeRef(BinaryReader reader) {
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var etype = (ElementType)reader.ReadInt32();
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switch (etype) {
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case ElementType.Void: return module.CorLibTypes.Void;
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case ElementType.Boolean: return module.CorLibTypes.Boolean;
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case ElementType.Char: return module.CorLibTypes.Char;
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case ElementType.I1: return module.CorLibTypes.SByte;
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case ElementType.U1: return module.CorLibTypes.Byte;
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case ElementType.I2: return module.CorLibTypes.Int16;
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case ElementType.U2: return module.CorLibTypes.UInt16;
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case ElementType.I4: return module.CorLibTypes.Int32;
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case ElementType.U4: return module.CorLibTypes.UInt32;
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case ElementType.I8: return module.CorLibTypes.Int64;
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case ElementType.U8: return module.CorLibTypes.UInt64;
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case ElementType.R4: return module.CorLibTypes.Single;
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case ElementType.R8: return module.CorLibTypes.Double;
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case ElementType.String: return module.CorLibTypes.String;
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case ElementType.TypedByRef: return module.CorLibTypes.TypedReference;
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case ElementType.I: return module.CorLibTypes.IntPtr;
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case ElementType.U: return module.CorLibTypes.UIntPtr;
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case ElementType.Object: return module.CorLibTypes.Object;
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case ElementType.ValueType:
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case ElementType.Var:
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case ElementType.MVar:
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return (module.ResolveToken(reader.ReadUInt32()) as ITypeDefOrRef).ToTypeSig();
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case ElementType.GenericInst:
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etype = (ElementType)reader.ReadInt32();
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if (etype == ElementType.ValueType)
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return (module.ResolveToken(reader.ReadUInt32()) as ITypeDefOrRef).ToTypeSig();
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// ElementType.Class
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return module.CorLibTypes.Object;
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case ElementType.Ptr:
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case ElementType.Class:
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case ElementType.Array:
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case ElementType.FnPtr:
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case ElementType.SZArray:
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case ElementType.ByRef:
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case ElementType.CModReqd:
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case ElementType.CModOpt:
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case ElementType.Internal:
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case ElementType.Sentinel:
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case ElementType.Pinned:
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default:
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return module.CorLibTypes.Object;
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}
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}
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List<ExceptionHandler> readExceptions(MethodDef cilMethod, CsvmMethodData csvmMethod, List<Instruction> cilInstructions) {
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var reader = new BinaryReader(new MemoryStream(csvmMethod.Exceptions));
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var ehs = new List<ExceptionHandler>();
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if (reader.BaseStream.Length == 0)
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return ehs;
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int numExceptions = reader.ReadInt32();
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if (numExceptions < 0)
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throw new ApplicationException("Invalid number of exception handlers");
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for (int i = 0; i < numExceptions; i++) {
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var eh = new ExceptionHandler((ExceptionHandlerType)reader.ReadInt32());
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eh.TryStart = getInstruction(cilInstructions, reader.ReadInt32());
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eh.TryEnd = getInstructionEnd(cilInstructions, reader.ReadInt32());
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eh.HandlerStart = getInstruction(cilInstructions, reader.ReadInt32());
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eh.HandlerEnd = getInstructionEnd(cilInstructions, reader.ReadInt32());
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if (eh.HandlerType == ExceptionHandlerType.Catch)
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eh.CatchType = module.ResolveToken(reader.ReadUInt32()) as ITypeDefOrRef;
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else if (eh.HandlerType == ExceptionHandlerType.Filter)
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eh.FilterStart = getInstruction(cilInstructions, reader.ReadInt32());
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ehs.Add(eh);
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}
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return ehs;
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}
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static Instruction getInstruction(IList<Instruction> instrs, int index) {
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return instrs[index];
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}
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static Instruction getInstructionEnd(IList<Instruction> instrs, int index) {
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index++;
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if (index == instrs.Count)
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return null;
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return instrs[index];
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}
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static Instruction getInstruction(IList<Instruction> instrs, Instruction source, int displ) {
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int sourceIndex = instrs.IndexOf(source);
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if (sourceIndex < 0)
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throw new ApplicationException("Could not find source instruction");
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return instrs[sourceIndex + displ];
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}
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void fixInstructionOperands(IList<Instruction> instrs) {
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foreach (var instr in instrs) {
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var op = instr.Operand as IVmOperand;
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if (op != null)
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instr.Operand = fixOperand(instrs, instr, op);
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}
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}
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object fixOperand(IList<Instruction> instrs, Instruction instr, IVmOperand vmOperand) {
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if (vmOperand is TokenOperand)
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return getMemberRef(((TokenOperand)vmOperand).token);
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if (vmOperand is TargetDisplOperand)
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return getInstruction(instrs, instr, ((TargetDisplOperand)vmOperand).displacement);
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if (vmOperand is SwitchTargetDisplOperand) {
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var targetDispls = ((SwitchTargetDisplOperand)vmOperand).targetDisplacements;
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Instruction[] targets = new Instruction[targetDispls.Length];
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for (int i = 0; i < targets.Length; i++)
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targets[i] = getInstruction(instrs, instr, targetDispls[i]);
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return targets;
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}
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if (vmOperand is ArgOperand || vmOperand is LocalOperand)
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return vmOperand;
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if (vmOperand is LoadFieldOperand)
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return fixLoadStoreFieldInstruction(instr, ((LoadFieldOperand)vmOperand).token, OpCodes.Ldsfld, OpCodes.Ldfld);
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if (vmOperand is LoadFieldAddressOperand)
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return fixLoadStoreFieldInstruction(instr, ((LoadFieldAddressOperand)vmOperand).token, OpCodes.Ldsflda, OpCodes.Ldflda);
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if (vmOperand is StoreFieldOperand)
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return fixLoadStoreFieldInstruction(instr, ((StoreFieldOperand)vmOperand).token, OpCodes.Stsfld, OpCodes.Stfld);
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throw new ApplicationException(string.Format("Unknown operand type: {0}", vmOperand.GetType()));
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}
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IField fixLoadStoreFieldInstruction(Instruction instr, int token, OpCode staticInstr, OpCode instanceInstr) {
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var fieldRef = module.ResolveToken(token) as IField;
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var field = deobfuscatorContext.resolveField(fieldRef);
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bool isStatic;
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if (field == null) {
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Logger.w("Could not resolve field {0:X8}. Assuming it's not static.", token);
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isStatic = false;
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}
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else
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isStatic = field.IsStatic;
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instr.OpCode = isStatic ? staticInstr : instanceInstr;
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return fieldRef;
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}
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ITokenOperand getMemberRef(int token) {
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var memberRef = module.ResolveToken(token) as ITokenOperand;
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if (memberRef == null)
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throw new ApplicationException(string.Format("Could not find member ref: {0:X8}", token));
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return memberRef;
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}
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static void restoreConstrainedPrefix(MethodDef method) {
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if (method == null || method.Body == null)
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return;
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count; i++) {
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var instr = instrs[i];
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if (instr.OpCode.Code != Code.Callvirt)
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continue;
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var calledMethod = instr.Operand as IMethod;
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if (calledMethod == null)
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continue;
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var sig = calledMethod.MethodSig;
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if (sig == null || !sig.HasThis)
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continue;
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var thisType = MethodStack.getLoadedType(method, instrs, i, sig.Params.Count) as ByRefSig;
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if (thisType == null)
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continue;
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if (hasPrefix(instrs, i, Code.Constrained))
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continue;
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instrs.Insert(i, Instruction.Create(OpCodes.Constrained, thisType.Next.ToTypeDefOrRef()));
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i++;
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}
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}
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static bool hasPrefix(IList<Instruction> instrs, int index, Code prefix) {
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index--;
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for (; index >= 0; index--) {
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var instr = instrs[index];
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if (instr.OpCode.OpCodeType != OpCodeType.Prefix)
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break;
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if (instr.OpCode.Code == prefix)
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return true;
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}
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return false;
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}
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}
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}
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