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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   *  Unless required by applicable law or agreed to in writing, software
12   *  distributed under the License is distributed on an "AS IS" BASIS,
13   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   *  See the License for the specific language governing permissions and
15   *  limitations under the License.
16   *
17   */
18  package org.apache.bcel.verifier.structurals;
19  
20  
21  import java.io.PrintWriter;
22  import java.io.StringWriter;
23  import java.util.ArrayList;
24  import java.util.List;
25  import java.util.Random;
26  import java.util.Vector;
27  
28  import org.apache.bcel.Const;
29  import org.apache.bcel.Repository;
30  import org.apache.bcel.classfile.JavaClass;
31  import org.apache.bcel.classfile.Method;
32  import org.apache.bcel.generic.ConstantPoolGen;
33  import org.apache.bcel.generic.InstructionHandle;
34  import org.apache.bcel.generic.JsrInstruction;
35  import org.apache.bcel.generic.MethodGen;
36  import org.apache.bcel.generic.ObjectType;
37  import org.apache.bcel.generic.RET;
38  import org.apache.bcel.generic.ReferenceType;
39  import org.apache.bcel.generic.ReturnInstruction;
40  import org.apache.bcel.generic.ReturnaddressType;
41  import org.apache.bcel.generic.Type;
42  import org.apache.bcel.verifier.PassVerifier;
43  import org.apache.bcel.verifier.VerificationResult;
44  import org.apache.bcel.verifier.Verifier;
45  import org.apache.bcel.verifier.exc.AssertionViolatedException;
46  import org.apache.bcel.verifier.exc.StructuralCodeConstraintException;
47  import org.apache.bcel.verifier.exc.VerifierConstraintViolatedException;
48  
49  /**
50   * This PassVerifier verifies a method of class file according to pass 3,
51   * so-called structural verification as described in The Java Virtual Machine
52   * Specification, 2nd edition.
53   * More detailed information is to be found at the do_verify() method's
54   * documentation.
55   *
56   * @version $Id: Pass3bVerifier.html 1018313 2017-09-18 09:03:04Z britter $
57   * @see #do_verify()
58   */
59  
60  public final class Pass3bVerifier extends PassVerifier{
61      /* TODO:    Throughout pass 3b, upper halves of LONG and DOUBLE
62                          are represented by Type.UNKNOWN. This should be changed
63                          in favour of LONG_Upper and DOUBLE_Upper as in pass 2. */
64  
65      /**
66       * An InstructionContextQueue is a utility class that holds
67       * (InstructionContext, ArrayList) pairs in a Queue data structure.
68       * This is used to hold information about InstructionContext objects
69       * externally --- i.e. that information is not saved inside the
70       * InstructionContext object itself. This is useful to save the
71       * execution path of the symbolic execution of the
72       * Pass3bVerifier - this is not information
73       * that belongs into the InstructionContext object itself.
74       * Only at "execute()"ing
75       * time, an InstructionContext object will get the current information
76       * we have about its symbolic execution predecessors.
77       */
78      private static final class InstructionContextQueue{
79          private final List<InstructionContext> ics = new Vector<>();
80          private final List<ArrayList<InstructionContext>> ecs = new Vector<>();
81          public void add(final InstructionContext ic, final ArrayList<InstructionContext> executionChain) {
82              ics.add(ic);
83              ecs.add(executionChain);
84          }
85          public boolean isEmpty() {
86              return ics.isEmpty();
87          }
88          public void remove(final int i) {
89              ics.remove(i);
90              ecs.remove(i);
91          }
92          public InstructionContext getIC(final int i) {
93              return ics.get(i);
94          }
95          public ArrayList<InstructionContext> getEC(final int i) {
96              return ecs.get(i);
97          }
98          public int size() {
99              return ics.size();
100         }
101     } // end Inner Class InstructionContextQueue
102 
103     /** In DEBUG mode, the verification algorithm is not randomized. */
104     private static final boolean DEBUG = true;
105 
106     /** The Verifier that created this. */
107     private final Verifier myOwner;
108 
109     /** The method number to verify. */
110     private final int method_no;
111 
112     /**
113      * This class should only be instantiated by a Verifier.
114      *
115      * @see org.apache.bcel.verifier.Verifier
116      */
117     public Pass3bVerifier(final Verifier owner, final int method_no) {
118         myOwner = owner;
119         this.method_no = method_no;
120     }
121 
122     /**
123      * Whenever the outgoing frame
124      * situation of an InstructionContext changes, all its successors are
125      * put [back] into the queue [as if they were unvisited].
126    * The proof of termination is about the existence of a
127    * fix point of frame merging.
128      */
129     private void circulationPump(final MethodGen m,final ControlFlowGraph cfg, final InstructionContext start,
130             final Frame vanillaFrame, final InstConstraintVisitor icv, final ExecutionVisitor ev) {
131         final Random random = new Random();
132         final InstructionContextQueue icq = new InstructionContextQueue();
133 
134         start.execute(vanillaFrame, new ArrayList<InstructionContext>(), icv, ev);
135         // new ArrayList() <=>    no Instruction was executed before
136         //                                    => Top-Level routine (no jsr call before)
137         icq.add(start, new ArrayList<InstructionContext>());
138 
139         // LOOP!
140         while (!icq.isEmpty()) {
141             InstructionContext u;
142             ArrayList<InstructionContext> ec;
143             if (!DEBUG) {
144                 final int r = random.nextInt(icq.size());
145                 u = icq.getIC(r);
146                 ec = icq.getEC(r);
147                 icq.remove(r);
148             }
149             else{
150                 u  = icq.getIC(0);
151                 ec = icq.getEC(0);
152                 icq.remove(0);
153             }
154 
155             @SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
156             final
157             ArrayList<InstructionContext> oldchain = (ArrayList<InstructionContext>) (ec.clone());
158             @SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
159             final
160             ArrayList<InstructionContext> newchain = (ArrayList<InstructionContext>) (ec.clone());
161             newchain.add(u);
162 
163             if ((u.getInstruction().getInstruction()) instanceof RET) {
164 //System.err.println(u);
165                 // We can only follow _one_ successor, the one after the
166                 // JSR that was recently executed.
167                 final RET ret = (RET) (u.getInstruction().getInstruction());
168                 final ReturnaddressType t = (ReturnaddressType) u.getOutFrame(oldchain).getLocals().get(ret.getIndex());
169                 final InstructionContext theSuccessor = cfg.contextOf(t.getTarget());
170 
171                 // Sanity check
172                 InstructionContext lastJSR = null;
173                 int skip_jsr = 0;
174                 for (int ss=oldchain.size()-1; ss >= 0; ss--) {
175                     if (skip_jsr < 0) {
176                         throw new AssertionViolatedException("More RET than JSR in execution chain?!");
177                     }
178 //System.err.println("+"+oldchain.get(ss));
179                     if ((oldchain.get(ss)).getInstruction().getInstruction() instanceof JsrInstruction) {
180                         if (skip_jsr == 0) {
181                             lastJSR = oldchain.get(ss);
182                             break;
183                         }
184                         skip_jsr--;
185                     }
186                     if ((oldchain.get(ss)).getInstruction().getInstruction() instanceof RET) {
187                         skip_jsr++;
188                     }
189                 }
190                 if (lastJSR == null) {
191                     throw new AssertionViolatedException("RET without a JSR before in ExecutionChain?! EC: '"+oldchain+"'.");
192                 }
193                 final JsrInstruction jsr = (JsrInstruction) (lastJSR.getInstruction().getInstruction());
194                 if ( theSuccessor != (cfg.contextOf(jsr.physicalSuccessor())) ) {
195                     throw new AssertionViolatedException("RET '"+u.getInstruction()+"' info inconsistent: jump back to '"+
196                         theSuccessor+"' or '"+cfg.contextOf(jsr.physicalSuccessor())+"'?");
197                 }
198 
199                 if (theSuccessor.execute(u.getOutFrame(oldchain), newchain, icv, ev)) {
200                     @SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
201                     final
202                     ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
203                     icq.add(theSuccessor, newchainClone);
204                 }
205             }
206             else{// "not a ret"
207 
208                 // Normal successors. Add them to the queue of successors.
209                 final InstructionContext[] succs = u.getSuccessors();
210                 for (final InstructionContext v : succs) {
211                     if (v.execute(u.getOutFrame(oldchain), newchain, icv, ev)) {
212                         @SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
213                         final
214                         ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
215                         icq.add(v, newchainClone);
216                     }
217                 }
218             }// end "not a ret"
219 
220             // Exception Handlers. Add them to the queue of successors.
221             // [subroutines are never protected; mandated by JustIce]
222             final ExceptionHandler[] exc_hds = u.getExceptionHandlers();
223             for (final ExceptionHandler exc_hd : exc_hds) {
224                 final InstructionContext v = cfg.contextOf(exc_hd.getHandlerStart());
225                 // TODO: the "oldchain" and "newchain" is used to determine the subroutine
226                 // we're in (by searching for the last JSR) by the InstructionContext
227                 // implementation. Therefore, we should not use this chain mechanism
228                 // when dealing with exception handlers.
229                 // Example: a JSR with an exception handler as its successor does not
230                 // mean we're in a subroutine if we go to the exception handler.
231                 // We should address this problem later; by now we simply "cut" the chain
232                 // by using an empty chain for the exception handlers.
233                 //if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(),
234                 // new OperandStack (u.getOutFrame().getStack().maxStack(),
235                 // (exc_hds[s].getExceptionType()==null? Type.THROWABLE : exc_hds[s].getExceptionType())) ), newchain), icv, ev) {
236                     //icq.add(v, (ArrayList) newchain.clone());
237                 if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(),
238                         new OperandStack (u.getOutFrame(oldchain).getStack().maxStack(),
239                         exc_hd.getExceptionType()==null? Type.THROWABLE : exc_hd.getExceptionType())),
240                         new ArrayList<InstructionContext>(), icv, ev)) {
241                     icq.add(v, new ArrayList<InstructionContext>());
242                 }
243             }
244 
245         }// while (!icq.isEmpty()) END
246 
247         InstructionHandle ih = start.getInstruction();
248         do{
249             if ((ih.getInstruction() instanceof ReturnInstruction) && (!(cfg.isDead(ih)))) {
250                 final InstructionContext ic = cfg.contextOf(ih);
251                 // TODO: This is buggy, we check only the top-level return instructions this way.
252                 // Maybe some maniac returns from a method when in a subroutine?
253                 final Frame f = ic.getOutFrame(new ArrayList<InstructionContext>());
254                 final LocalVariables lvs = f.getLocals();
255                 for (int i=0; i<lvs.maxLocals(); i++) {
256                     if (lvs.get(i) instanceof UninitializedObjectType) {
257                         this.addMessage("Warning: ReturnInstruction '"+ic+
258                             "' may leave method with an uninitialized object in the local variables array '"+lvs+"'.");
259                     }
260                 }
261                 final OperandStack os = f.getStack();
262                 for (int i=0; i<os.size(); i++) {
263                     if (os.peek(i) instanceof UninitializedObjectType) {
264                         this.addMessage("Warning: ReturnInstruction '"+ic+
265                             "' may leave method with an uninitialized object on the operand stack '"+os+"'.");
266                     }
267                 }
268                 //see JVM $4.8.2
269                 Type returnedType = null;
270                 final OperandStack inStack = ic.getInFrame().getStack();
271                 if (inStack.size() >= 1) {
272                     returnedType = inStack.peek();
273                 } else {
274                     returnedType = Type.VOID;
275                 }
276 
277                 if (returnedType != null) {
278                     if (returnedType instanceof ReferenceType) {
279                         try {
280                             if (!((ReferenceType) returnedType).isCastableTo(m.getReturnType())) {
281                                 invalidReturnTypeError(returnedType, m);
282                             }
283                         } catch (final ClassNotFoundException e) {
284                             // Don't know what do do now, so raise RuntimeException
285                             throw new RuntimeException(e);
286                         }
287                     } else if (!returnedType.equals(m.getReturnType().normalizeForStackOrLocal())) {
288                         invalidReturnTypeError(returnedType, m);
289                     }
290                 }
291             }
292         } while ((ih = ih.getNext()) != null);
293 
294      }
295 
296     /**
297      * Throws an exception indicating the returned type is not compatible with the return type of the given method
298      * @throws StructuralCodeConstraintException always
299      * @since 6.0
300      */
301     public void invalidReturnTypeError(final Type returnedType, final MethodGen m) {
302         throw new StructuralCodeConstraintException(
303             "Returned type "+returnedType+" does not match Method's return type "+m.getReturnType());
304     }
305 
306     /**
307      * Pass 3b implements the data flow analysis as described in the Java Virtual
308      * Machine Specification, Second Edition.
309       * Later versions will use LocalVariablesInfo objects to verify if the
310       * verifier-inferred types and the class file's debug information (LocalVariables
311       * attributes) match [TODO].
312       *
313       * @see org.apache.bcel.verifier.statics.LocalVariablesInfo
314       * @see org.apache.bcel.verifier.statics.Pass2Verifier#getLocalVariablesInfo(int)
315       */
316     @Override
317     public VerificationResult do_verify() {
318         if (! myOwner.doPass3a(method_no).equals(VerificationResult.VR_OK)) {
319             return VerificationResult.VR_NOTYET;
320         }
321 
322         // Pass 3a ran before, so it's safe to assume the JavaClass object is
323         // in the BCEL repository.
324         JavaClass jc;
325         try {
326             jc = Repository.lookupClass(myOwner.getClassName());
327         } catch (final ClassNotFoundException e) {
328             // FIXME: maybe not the best way to handle this
329             throw new AssertionViolatedException("Missing class: " + e, e);
330         }
331 
332         final ConstantPoolGen constantPoolGen = new ConstantPoolGen(jc.getConstantPool());
333         // Init Visitors
334         final InstConstraintVisitor icv = new InstConstraintVisitor();
335         icv.setConstantPoolGen(constantPoolGen);
336 
337         final ExecutionVisitor ev = new ExecutionVisitor();
338         ev.setConstantPoolGen(constantPoolGen);
339 
340         final Method[] methods = jc.getMethods(); // Method no "method_no" exists, we ran Pass3a before on it!
341 
342         try{
343 
344             final MethodGen mg = new MethodGen(methods[method_no], myOwner.getClassName(), constantPoolGen);
345 
346             icv.setMethodGen(mg);
347 
348             ////////////// DFA BEGINS HERE ////////////////
349             if (! (mg.isAbstract() || mg.isNative()) ) { // IF mg HAS CODE (See pass 2)
350 
351                 final ControlFlowGraph cfg = new ControlFlowGraph(mg);
352 
353                 // Build the initial frame situation for this method.
354                 final Frame f = new Frame(mg.getMaxLocals(),mg.getMaxStack());
355                 if ( !mg.isStatic() ) {
356                     if (mg.getName().equals(Const.CONSTRUCTOR_NAME)) {
357                         Frame.setThis(new UninitializedObjectType(ObjectType.getInstance(jc.getClassName())));
358                         f.getLocals().set(0, Frame.getThis());
359                     }
360                     else{
361                         Frame.setThis(null);
362                         f.getLocals().set(0, ObjectType.getInstance(jc.getClassName()));
363                     }
364                 }
365                 final Type[] argtypes = mg.getArgumentTypes();
366                 int twoslotoffset = 0;
367                 for (int j=0; j<argtypes.length; j++) {
368                     if (argtypes[j] == Type.SHORT || argtypes[j] == Type.BYTE ||
369                         argtypes[j] == Type.CHAR || argtypes[j] == Type.BOOLEAN) {
370                         argtypes[j] = Type.INT;
371                     }
372                     f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), argtypes[j]);
373                     if (argtypes[j].getSize() == 2) {
374                         twoslotoffset++;
375                         f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), Type.UNKNOWN);
376                     }
377                 }
378                 circulationPump(mg,cfg, cfg.contextOf(mg.getInstructionList().getStart()), f, icv, ev);
379             }
380         }
381         catch (final VerifierConstraintViolatedException ce) {
382             ce.extendMessage("Constraint violated in method '"+methods[method_no]+"':\n","");
383             return new VerificationResult(VerificationResult.VERIFIED_REJECTED, ce.getMessage());
384         }
385         catch (final RuntimeException re) {
386             // These are internal errors
387 
388             final StringWriter sw = new StringWriter();
389             final PrintWriter pw = new PrintWriter(sw);
390             re.printStackTrace(pw);
391 
392             throw new AssertionViolatedException("Some RuntimeException occured while verify()ing class '"+jc.getClassName()+
393                 "', method '"+methods[method_no]+"'. Original RuntimeException's stack trace:\n---\n"+sw+"---\n", re);
394         }
395         return VerificationResult.VR_OK;
396     }
397 
398     /** Returns the method number as supplied when instantiating. */
399     public int getMethodNo() {
400         return method_no;
401     }
402 }