PossibleUnsuspectedSerialization.java

/*
 * fb-contrib - Auxiliary detectors for Java programs
 * Copyright (C) 2005-2017 Dave Brosius
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package com.mebigfatguy.fbcontrib.detect;

import org.apache.bcel.classfile.Field;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;

import com.mebigfatguy.fbcontrib.utils.BugType;
import com.mebigfatguy.fbcontrib.utils.SignatureUtils;
import com.mebigfatguy.fbcontrib.utils.Values;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.OpcodeStack;
import edu.umd.cs.findbugs.ba.ClassContext;

/**
 * looks for serialization of non-static inner classes. As this serializes the
 * enclosing class, it may unintentially bring in more to the serialization than
 * is wanted
 */
public class PossibleUnsuspectedSerialization extends BytecodeScanningDetector {

    private final BugReporter bugReporter;
    private OpcodeStack stack;

    /**
     * constructs a PUS detector given the reporter to report bugs on
     *
     * @param bugReporter
     *            the sync of bug reports
     */
    public PossibleUnsuspectedSerialization(BugReporter bugReporter) {
        this.bugReporter = bugReporter;
    }

    /**
     * implements the visitor to setup and tear down the opcode stack
     *
     * @param classContext
     *            the context object of the currently parsed class
     */
    @Override
    public void visitClassContext(ClassContext classContext) {
        try {
            stack = new OpcodeStack();
            super.visitClassContext(classContext);
        } finally {
            stack = null;
        }
    }

    /**
     * implements the visitor to reset the opcode stack
     *
     * @param obj
     *            the context object of the currently parsed method
     */
    @Override
    public void visitMethod(Method obj) {
        stack.resetForMethodEntry(this);
        super.visitMethod(obj);
    }

    /**
     * implements the visitor to look for serialization of an object that is an
     * non-static inner class.
     *
     * @param seen
     *            the context object of the currently parsed instruction
     */
    @Override
    public void sawOpcode(int seen) {
        try {
            stack.precomputation(this);

            if (seen == INVOKEVIRTUAL) {
                String clsName = getClassConstantOperand();
                if ("java/io/ObjectOutputStream".equals(clsName)) {
                    String name = getNameConstantOperand();
                    if ("writeObject".equals(name) && (stack.getStackDepth() > 0)) {
                        OpcodeStack.Item item = stack.getStackItem(0);
                        JavaClass cls = item.getJavaClass();

                        if ((cls != null) && cls.getClassName().contains("$") && hasOuterClassSyntheticReference(cls)) {
                            bugReporter.reportBug(new BugInstance(this, BugType.PUS_POSSIBLE_UNSUSPECTED_SERIALIZATION.name(), NORMAL_PRIORITY)
                                    .addClass(this).addMethod(this).addSourceLine(this));
                        }
                    }
                }
            }
        } catch (ClassNotFoundException cnfe) {
            bugReporter.reportMissingClass(cnfe);
        } finally {
            stack.sawOpcode(this, seen);
        }
    }

    private static boolean hasOuterClassSyntheticReference(JavaClass cls) {
        Field[] fields = cls.getFields();
        for (Field f : fields) {
            if (f.isSynthetic()) {
                String sig = f.getSignature();
                if (sig.startsWith(Values.SIG_QUALIFIED_CLASS_PREFIX)) {
                    sig = SignatureUtils.trimSignature(sig);
                    if (cls.getClassName().startsWith(sig)) {
                        return true;
                    }
                }
            }
        }

        return false;
    }

}