334 lines
9.5 KiB
C#
334 lines
9.5 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 Mono.Cecil.Metadata;
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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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List<ParameterDefinition> parameters;
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ParameterDefinition arg1, arg2;
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Value returnValue;
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MethodDefinition 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 changed = 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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changed |= inlineMethod(instr, i);
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}
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return changed;
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}
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bool inlineMethod(Instruction callInstr, int instrIndex) {
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var method = callInstr.Operand as MethodDefinition;
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if (method == null)
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return false;
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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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bool inlineMethod(MethodDefinition methodToInline, int instrIndex, int const1, int const2) {
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this.methodToInline = methodToInline = cflowDeobfuscator.deobfuscate(methodToInline);
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parameters = DotNetUtils.getParameters(methodToInline);
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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.init(methodToInline);
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foreach (var arg in parameters) {
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if (arg.ParameterType.EType >= ElementType.Boolean && arg.ParameterType.EType <= 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, Instruction.Create(OpCodes.Pop));
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block.insert(instrIndex, Instruction.Create(OpCodes.Pop));
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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 = DotNetUtils.getParameter(parameters, instr);
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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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DotNetUtils.calculateStackUsage(lastInstr, false, out pushes, out pops);
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for (int i = 0; i < pops; i++)
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instructionEmulator.pop();
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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(MethodDefinition 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.GenericParameters.Count > 0)
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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.Parameters;
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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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var param1 = parameters[paramCount - 1];
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var param2 = parameters[paramCount - 2];
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if (!isIntType(param1.ParameterType.EType))
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return false;
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if (!isIntType(param2.ParameterType.EType))
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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(MethodDefinition 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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