292 lines
8.8 KiB
C#
292 lines
8.8 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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namespace de4dot.blocks.cflow {
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public abstract class MethodCallInlinerBase : IBlocksDeobfuscator {
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// We can't catch all infinite loops, so inline methods at most this many times
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const int MAX_ITERATIONS = 10;
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protected Blocks blocks;
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protected Block block;
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int iteration;
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AccessChecker accessChecker;
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public bool ExecuteIfNotModified { get; set; }
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public void DeobfuscateBegin(Blocks blocks) {
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this.blocks = blocks;
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iteration = 0;
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}
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public bool Deobfuscate(List<Block> allBlocks) {
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if (iteration++ >= MAX_ITERATIONS)
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return false;
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bool modified = false;
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foreach (var block in allBlocks) {
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this.block = block;
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modified |= DeobfuscateInternal();
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}
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return modified;
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}
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protected abstract bool DeobfuscateInternal();
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protected class InstructionPatcher {
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readonly int patchIndex;
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public readonly int afterIndex;
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public readonly Instruction lastInstr;
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readonly Instr clonedInstr;
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public InstructionPatcher(int patchIndex, int afterIndex, Instruction lastInstr) {
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this.patchIndex = patchIndex;
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this.afterIndex = afterIndex;
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this.lastInstr = lastInstr;
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this.clonedInstr = new Instr(lastInstr.Clone());
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}
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public void Patch(Block block) {
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block.Instructions[patchIndex] = clonedInstr;
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}
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}
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protected bool InlineLoadMethod(int patchIndex, MethodDef methodToInline, Instruction loadInstr, int instrIndex) {
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if (!IsReturn(methodToInline, instrIndex))
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return false;
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int methodArgsCount = DotNetUtils.GetArgsCount(methodToInline);
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for (int i = 0; i < methodArgsCount; i++)
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block.Insert(patchIndex++, OpCodes.Pop.ToInstruction());
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block.Instructions[patchIndex] = new Instr(loadInstr.Clone());
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return true;
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}
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protected bool InlineOtherMethod(int patchIndex, MethodDef methodToInline, Instruction instr, int instrIndex) {
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return InlineOtherMethod(patchIndex, methodToInline, instr, instrIndex, 0);
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}
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protected bool InlineOtherMethod(int patchIndex, MethodDef methodToInline, Instruction instr, int instrIndex, int popLastArgs) {
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return PatchMethod(methodToInline, TryInlineOtherMethod(patchIndex, methodToInline, instr, instrIndex, popLastArgs));
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}
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protected bool PatchMethod(MethodDef methodToInline, InstructionPatcher patcher) {
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if (patcher == null)
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return false;
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if (!IsReturn(methodToInline, patcher.afterIndex))
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return false;
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patcher.Patch(block);
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return true;
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}
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protected InstructionPatcher TryInlineOtherMethod(int patchIndex, MethodDef methodToInline, Instruction instr, int instrIndex) {
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return TryInlineOtherMethod(patchIndex, methodToInline, instr, instrIndex, 0);
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}
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protected virtual Instruction OnAfterLoadArg(MethodDef methodToInline, Instruction instr, ref int instrIndex) {
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return instr;
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}
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protected InstructionPatcher TryInlineOtherMethod(int patchIndex, MethodDef methodToInline, Instruction instr, int instrIndex, int popLastArgs) {
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int loadIndex = 0;
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int methodArgsCount = DotNetUtils.GetArgsCount(methodToInline);
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bool foundLdarga = false;
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while (instr != null && loadIndex < methodArgsCount) {
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bool isLdarg = true;
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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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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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break;
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case Code.Ldarga:
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case Code.Ldarga_S:
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foundLdarga = true;
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break;
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default:
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isLdarg = false;
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break;
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}
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if (!isLdarg)
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break;
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if (instr.GetParameterIndex() != loadIndex)
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return null;
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loadIndex++;
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instr = DotNetUtils.GetInstruction(methodToInline.Body.Instructions, ref instrIndex);
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instr = OnAfterLoadArg(methodToInline, instr, ref instrIndex);
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}
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if (instr == null || loadIndex != methodArgsCount - popLastArgs)
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return null;
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switch (instr.OpCode.Code) {
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case Code.Call:
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case Code.Callvirt:
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if (foundLdarga)
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return null;
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var callInstr = instr;
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var calledMethod = callInstr.Operand as IMethod;
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if (calledMethod == null)
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return null;
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if (!IsCompatibleType(-1, calledMethod.MethodSig.RetType, methodToInline.MethodSig.RetType))
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return null;
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if (!CheckSameMethods(calledMethod, methodToInline, popLastArgs))
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return null;
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if (!HasAccessTo(instr.Operand))
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return null;
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return new InstructionPatcher(patchIndex, instrIndex, callInstr);
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case Code.Newobj:
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if (foundLdarga)
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return null;
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var newobjInstr = instr;
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var ctor = newobjInstr.Operand as IMethod;
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if (ctor == null)
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return null;
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if (!IsCompatibleType(-1, ctor.DeclaringType, methodToInline.MethodSig.RetType))
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return null;
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var methodArgs = methodToInline.Parameters;
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var calledMethodArgs = DotNetUtils.GetArgs(ctor);
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if (methodArgs.Count + 1 - popLastArgs != calledMethodArgs.Count)
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return null;
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for (int i = 1; i < calledMethodArgs.Count; i++) {
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if (!IsCompatibleType(i, calledMethodArgs[i], methodArgs[i - 1].Type))
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return null;
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}
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if (!HasAccessTo(instr.Operand))
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return null;
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return new InstructionPatcher(patchIndex, instrIndex, newobjInstr);
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case Code.Ldfld:
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case Code.Ldflda:
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case Code.Ldftn:
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case Code.Ldvirtftn:
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case Code.Ldlen:
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case Code.Initobj:
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case Code.Isinst:
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case Code.Castclass:
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case Code.Newarr:
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case Code.Ldtoken:
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case Code.Unbox_Any:
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var ldInstr = instr;
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if (methodArgsCount != 1)
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return null;
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if (instr.OpCode.OperandType != OperandType.InlineNone && !HasAccessTo(instr.Operand))
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return null;
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return new InstructionPatcher(patchIndex, instrIndex, ldInstr);
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default:
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return null;
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}
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}
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bool HasAccessTo(object operand) {
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if (operand == null)
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return false;
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accessChecker.UserType = blocks.Method.DeclaringType;
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return accessChecker.CanAccess(operand) ?? GetDefaultAccessResult();
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}
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protected virtual bool GetDefaultAccessResult() {
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return true;
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}
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protected virtual bool IsReturn(MethodDef methodToInline, int instrIndex) {
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var instr = DotNetUtils.GetInstruction(methodToInline.Body.Instructions, ref instrIndex);
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return instr != null && instr.OpCode.Code == Code.Ret;
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}
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protected bool CheckSameMethods(IMethod method, MethodDef methodToInline) {
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return CheckSameMethods(method, methodToInline, 0);
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}
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protected bool CheckSameMethods(IMethod method, MethodDef methodToInline, int ignoreLastMethodToInlineArgs) {
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var methodToInlineArgs = methodToInline.Parameters;
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var methodArgs = DotNetUtils.GetArgs(method);
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bool hasImplicitThis = method.MethodSig.ImplicitThis;
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if (methodToInlineArgs.Count - ignoreLastMethodToInlineArgs != methodArgs.Count)
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return false;
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for (int i = 0; i < methodArgs.Count; i++) {
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var methodArg = methodArgs[i];
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var methodToInlineArg = GetArgType(methodToInline, methodToInlineArgs[i].Type);
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if (!IsCompatibleType(i, methodArg, methodToInlineArg)) {
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if (i != 0 || !hasImplicitThis)
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return false;
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if (!isCompatibleValueThisPtr(methodArg, methodToInlineArg))
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return false;
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}
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}
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return true;
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}
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static TypeSig GetArgType(MethodDef method, TypeSig arg) {
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if (arg.GetElementType() != ElementType.MVar)
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return arg;
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var mvar = (GenericMVar)arg;
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foreach (var gp in method.GenericParameters) {
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if (gp.Number != mvar.Number)
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continue;
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foreach (var gpc in gp.GenericParamConstraints)
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return gpc.Constraint.ToTypeSig();
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}
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return arg;
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}
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protected virtual bool IsCompatibleType(int paramIndex, IType origType, IType newType) {
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return new SigComparer().Equals(origType, newType);
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}
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static bool isCompatibleValueThisPtr(IType origType, IType newType) {
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var newByRef = newType as ByRefSig;
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if (newByRef == null)
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return false;
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if (!IsValueType(newByRef.Next) || !IsValueType(origType))
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return false;
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return new SigComparer().Equals(origType, newByRef.Next);
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}
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protected static bool IsValueType(IType type) {
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if (type == null)
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return false;
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var ts = type as TypeSig;
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if (ts == null)
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return type.IsValueType;
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return ts.IsValueType && ts.ElementType != ElementType.Void;
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}
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}
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}
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