353 lines
10 KiB
C#
353 lines
10 KiB
C#
/*
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Copyright (C) 2011-2015 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 dnlib.DotNet;
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using dnlib.DotNet.Emit;
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using de4dot.blocks;
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using de4dot.blocks.cflow;
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namespace de4dot.code.deobfuscators.DeepSea {
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class DsMethodCallInliner : MethodCallInlinerBase {
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InstructionEmulator instructionEmulator = new InstructionEmulator();
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IList<Parameter> parameters;
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Parameter arg1, arg2;
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Value returnValue;
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MethodDef methodToInline;
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CachedCflowDeobfuscator cflowDeobfuscator;
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public DsMethodCallInliner(CachedCflowDeobfuscator cflowDeobfuscator) {
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this.cflowDeobfuscator = cflowDeobfuscator;
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}
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protected override bool DeobfuscateInternal() {
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bool modified = false;
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var instructions = block.Instructions;
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for (int i = 0; i < instructions.Count; i++) {
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var instr = instructions[i].Instruction;
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if (instr.OpCode.Code == Code.Call)
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modified |= InlineMethod(instr, i);
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}
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return modified;
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}
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bool InlineMethod(Instruction callInstr, int instrIndex) {
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var method = callInstr.Operand as MethodDef;
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if (method == null) {
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var ms = callInstr.Operand as MethodSpec;
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if (ms != null)
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method = ms.Method as MethodDef;
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if (method == null)
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return false;
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}
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if (!CanInline(method))
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return false;
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if (instrIndex < 2)
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return false;
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var ldci4_1st = block.Instructions[instrIndex - 2];
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var ldci4_2nd = block.Instructions[instrIndex - 1];
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if (!ldci4_1st.IsLdcI4() || !ldci4_2nd.IsLdcI4())
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return false;
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if (!InlineMethod(method, instrIndex, ldci4_1st.GetLdcI4Value(), ldci4_2nd.GetLdcI4Value()))
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return false;
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return true;
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}
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protected override Instruction OnAfterLoadArg(MethodDef methodToInline, Instruction instr, ref int instrIndex) {
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if (instr.OpCode.Code != Code.Box)
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return instr;
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if (methodToInline.MethodSig.GetGenParamCount() == 0)
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return instr;
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return DotNetUtils.GetInstruction(methodToInline.Body.Instructions, ref instrIndex);
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}
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bool InlineMethod(MethodDef methodToInline, int instrIndex, int const1, int const2) {
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this.methodToInline = methodToInline = cflowDeobfuscator.Deobfuscate(methodToInline);
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parameters = methodToInline.Parameters;
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arg1 = parameters[parameters.Count - 2];
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arg2 = parameters[parameters.Count - 1];
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returnValue = null;
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instructionEmulator.Initialize(methodToInline);
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foreach (var arg in parameters) {
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if (!arg.IsNormalMethodParameter)
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continue;
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if (arg.Type.ElementType >= ElementType.Boolean && arg.Type.ElementType <= ElementType.U4)
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instructionEmulator.SetArg(arg, new Int32Value(0));
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}
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instructionEmulator.SetArg(arg1, new Int32Value(const1));
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instructionEmulator.SetArg(arg2, new Int32Value(const2));
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int index = 0;
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if (!EmulateInstructions(ref index, false))
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return false;
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var patcher = TryInlineOtherMethod(instrIndex, methodToInline, methodToInline.Body.Instructions[index], index + 1, 2);
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if (patcher == null)
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return false;
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if (!EmulateToReturn(patcher.afterIndex, patcher.lastInstr))
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return false;
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patcher.Patch(block);
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block.Insert(instrIndex, OpCodes.Pop.ToInstruction());
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block.Insert(instrIndex, OpCodes.Pop.ToInstruction());
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return true;
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}
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bool EmulateInstructions(ref int index, bool allowUnknownArgs) {
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Instruction instr;
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var instrs = methodToInline.Body.Instructions;
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int counter = 0;
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var foundOpCodes = new Dictionary<Code, bool>();
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bool checkInstrs = false;
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while (true) {
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if (counter++ >= 50)
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return false;
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if (index < 0 || index >= instrs.Count)
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return false;
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instr = instrs[index];
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foundOpCodes[instr.OpCode.Code] = true;
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switch (instr.OpCode.Code) {
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case Code.Stloc:
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case Code.Stloc_S:
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case Code.Stloc_0:
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case Code.Stloc_1:
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case Code.Stloc_2:
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case Code.Stloc_3:
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case Code.Ldloc:
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case Code.Ldloc_S:
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case Code.Ldloc_0:
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case Code.Ldloc_1:
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case Code.Ldloc_2:
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case Code.Ldloc_3:
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case Code.Ldc_I4:
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case Code.Ldc_I4_0:
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case Code.Ldc_I4_1:
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case Code.Ldc_I4_2:
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case Code.Ldc_I4_3:
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case Code.Ldc_I4_4:
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case Code.Ldc_I4_5:
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case Code.Ldc_I4_6:
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case Code.Ldc_I4_7:
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case Code.Ldc_I4_8:
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case Code.Ldc_I4_M1:
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case Code.Ldc_I4_S:
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case Code.Add:
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case Code.Sub:
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case Code.Xor:
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case Code.Or:
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case Code.Nop:
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case Code.Dup:
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case Code.Mul:
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case Code.Rem:
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case Code.Div:
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instructionEmulator.Emulate(instr);
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index++;
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break;
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case Code.Ldarg:
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case Code.Ldarg_S:
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case Code.Ldarg_0:
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case Code.Ldarg_1:
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case Code.Ldarg_2:
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case Code.Ldarg_3:
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var arg = instr.GetParameter(parameters);
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if (arg != arg1 && arg != arg2) {
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if (!allowUnknownArgs)
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goto done;
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checkInstrs = true;
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}
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instructionEmulator.Emulate(instr);
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index++;
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break;
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case Code.Call:
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case Code.Callvirt:
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case Code.Newobj:
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goto done;
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case Code.Switch:
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var value = instructionEmulator.Pop() as Int32Value;
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if (value == null || !value.AllBitsValid())
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return false;
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var targets = (Instruction[])instr.Operand;
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if (value.Value >= 0 && value.Value < targets.Length)
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index = instrs.IndexOf(targets[value.Value]);
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else
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index++;
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break;
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case Code.Br:
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case Code.Br_S:
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index = instrs.IndexOf((Instruction)instr.Operand);
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break;
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case Code.Brtrue:
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case Code.Brtrue_S:
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index = EmulateBrtrue(index);
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break;
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case Code.Brfalse:
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case Code.Brfalse_S:
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index = EmulateBrfalse(index);
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break;
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case Code.Isinst:
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case Code.Castclass:
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if (returnValue != null && instructionEmulator.Peek() == returnValue) {
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// Do nothing
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}
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else
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instructionEmulator.Emulate(instr);
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index++;
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break;
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default:
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if (instr.OpCode.OpCodeType != OpCodeType.Prefix)
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goto done;
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index++;
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break;
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}
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}
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done:
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if (checkInstrs) {
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if (!foundOpCodes.ContainsKey(Code.Ldc_I4_1))
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return false;
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if (!foundOpCodes.ContainsKey(Code.Ldc_I4_2))
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return false;
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if (!foundOpCodes.ContainsKey(Code.Add))
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return false;
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if (!foundOpCodes.ContainsKey(Code.Dup))
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return false;
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if (!foundOpCodes.ContainsKey(Code.Mul))
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return false;
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if (!foundOpCodes.ContainsKey(Code.Rem))
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return false;
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if (!foundOpCodes.ContainsKey(Code.Brtrue) && !foundOpCodes.ContainsKey(Code.Brtrue_S) &&
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!foundOpCodes.ContainsKey(Code.Brfalse) && !foundOpCodes.ContainsKey(Code.Brfalse_S))
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return false;
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}
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return true;
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}
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int EmulateBranch(int stackArgs, Bool3 cond, Instruction instrTrue, Instruction instrFalse) {
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if (cond == Bool3.Unknown)
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return -1;
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Instruction instr = cond == Bool3.True ? instrTrue : instrFalse;
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return methodToInline.Body.Instructions.IndexOf(instr);
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}
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int EmulateBrtrue(int instrIndex) {
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var val1 = instructionEmulator.Pop();
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var instr = methodToInline.Body.Instructions[instrIndex];
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var instrTrue = (Instruction)instr.Operand;
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var instrFalse = methodToInline.Body.Instructions[instrIndex + 1];
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if (val1.IsInt32())
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return EmulateBranch(1, Int32Value.CompareTrue((Int32Value)val1), instrTrue, instrFalse);
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return -1;
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}
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int EmulateBrfalse(int instrIndex) {
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var val1 = instructionEmulator.Pop();
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var instr = methodToInline.Body.Instructions[instrIndex];
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var instrTrue = (Instruction)instr.Operand;
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var instrFalse = methodToInline.Body.Instructions[instrIndex + 1];
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if (val1.IsInt32())
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return EmulateBranch(1, Int32Value.CompareFalse((Int32Value)val1), instrTrue, instrFalse);
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return -1;
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}
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bool EmulateToReturn(int index, Instruction lastInstr) {
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int pushes, pops;
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lastInstr.CalculateStackUsage(false, out pushes, out pops);
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instructionEmulator.Pop(pops);
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returnValue = null;
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if (pushes != 0) {
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returnValue = new UnknownValue();
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instructionEmulator.SetProtected(returnValue);
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instructionEmulator.Push(returnValue);
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}
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if (!EmulateInstructions(ref index, true))
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return false;
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if (index >= methodToInline.Body.Instructions.Count)
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return false;
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if (methodToInline.Body.Instructions[index].OpCode.Code != Code.Ret)
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return false;
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if (returnValue != null) {
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if (instructionEmulator.Pop() != returnValue)
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return false;
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}
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return instructionEmulator.StackSize() == 0;
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}
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public static bool CanInline(MethodDef method) {
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if (method == null || method.Body == null)
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return false;
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if (method.Attributes != (MethodAttributes.Assembly | MethodAttributes.Static))
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return false;
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if (method.Body.ExceptionHandlers.Count > 0)
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return false;
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var parameters = method.MethodSig.GetParams();
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int paramCount = parameters.Count;
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if (paramCount < 2)
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return false;
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if (method.GenericParameters.Count > 0) {
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foreach (var gp in method.GenericParameters) {
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if (gp.GenericParamConstraints.Count == 0)
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return false;
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}
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}
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var param1 = parameters[paramCount - 1];
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var param2 = parameters[paramCount - 2];
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if (!IsIntType(param1.ElementType))
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return false;
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if (!IsIntType(param2.ElementType))
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return false;
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return true;
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}
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static bool IsIntType(ElementType etype) {
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return etype == ElementType.Char || etype == ElementType.I2 || etype == ElementType.I4;
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}
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protected override bool IsReturn(MethodDef methodToInline, int instrIndex) {
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int oldIndex = instrIndex;
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if (base.IsReturn(methodToInline, oldIndex))
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return true;
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return false;
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}
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}
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}
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