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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *   https://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.apache.bcel.verifier.structurals;
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, so-called structural verification as described
51   * in The Java Virtual Machine Specification, 2nd edition. More detailed information is to be found at the do_verify()
52   * method's documentation.
53   *
54   * @see #do_verify()
55   */
56  
57  public final class Pass3bVerifier extends PassVerifier {
58      /*
59       * TODO: Throughout pass 3b, upper halves of LONG and DOUBLE are represented by Type.UNKNOWN. This should be changed in
60       * favor of LONG_Upper and DOUBLE_Upper as in pass 2.
61       */
62  
63      /**
64       * An InstructionContextQueue is a utility class that holds (InstructionContext, ArrayList) pairs in a Queue data
65       * structure. This is used to hold information about InstructionContext objects externally --- i.e. that information is
66       * not saved inside the InstructionContext object itself. This is useful to save the execution path of the symbolic
67       * execution of the Pass3bVerifier - this is not information that belongs into the InstructionContext object itself.
68       * Only at "execute()"ing time, an InstructionContext object will get the current information we have about its symbolic
69       * execution predecessors.
70       */
71      private static final class InstructionContextQueue {
72          // The following two fields together represent the queue.
73          /** The first elements from pairs in the queue. */
74          private final List<InstructionContext> ics = new Vector<>();
75          /** The second elements from pairs in the queue. */
76          private final List<ArrayList<InstructionContext>> ecs = new Vector<>();
77  
78          /**
79           * Adds an (InstructionContext, ExecutionChain) pair to this queue.
80           *
81           * @param ic the InstructionContext
82           * @param executionChain the ExecutionChain
83           */
84          public void add(final InstructionContext ic, final ArrayList<InstructionContext> executionChain) {
85              ics.add(ic);
86              ecs.add(executionChain);
87          }
88  
89          /**
90           * Gets a specific ExecutionChain from the queue.
91           *
92           * @param i the index of the item to be fetched
93           * @return the indicated ExecutionChain
94           */
95          public ArrayList<InstructionContext> getEC(final int i) {
96              return ecs.get(i);
97          }
98  
99          /**
100          * Gets a specific InstructionContext from the queue.
101          *
102          * @param i the index of the item to be fetched
103          * @return the indicated InstructionContext
104          */
105         public InstructionContext getIC(final int i) {
106             return ics.get(i);
107         }
108 
109         /**
110          * Tests if InstructionContext queue is empty.
111          *
112          * @return true if the InstructionContext queue is empty.
113          */
114         public boolean isEmpty() {
115             return ics.isEmpty();
116         }
117 
118         /**
119          * Removes a specific (InstructionContext, ExecutionChain) pair from their respective queues.
120          *
121          * @param i the index of the items to be removed
122          */
123         public void remove(final int i) {
124             ics.remove(i);
125             ecs.remove(i);
126         }
127 
128         /**
129          * Gets the size of the InstructionContext queue.
130          *
131          * @return the size of the InstructionQueue
132          */
133         public int size() {
134             return ics.size();
135         }
136     } // end Inner Class InstructionContextQueue
137 
138     /** In DEBUG mode, the verification algorithm is not randomized. */
139     private static final boolean DEBUG = true;
140 
141     /** The Verifier that created this. */
142     private final Verifier myOwner;
143 
144     /** The method number to verify. */
145     private final int methodNo;
146 
147     /**
148      * This class should only be instantiated by a Verifier.
149      *
150      * @see org.apache.bcel.verifier.Verifier
151      */
152     public Pass3bVerifier(final Verifier myOwner, final int methodNo) {
153         this.myOwner = myOwner;
154         this.methodNo = methodNo;
155     }
156 
157     /**
158      * Whenever the outgoing frame situation of an InstructionContext changes, all its successors are put [back] into the
159      * queue [as if they were unvisited]. The proof of termination is about the existence of a fix point of frame merging.
160      */
161     private void circulationPump(final MethodGen m, final ControlFlowGraph cfg, final InstructionContext start, final Frame vanillaFrame,
162         final InstConstraintVisitor icv, final ExecutionVisitor ev) {
163         final Random random = new Random();
164         final InstructionContextQueue icq = new InstructionContextQueue();
165 
166         start.execute(vanillaFrame, new ArrayList<>(), icv, ev);
167         // new ArrayList() <=> no Instruction was executed before
168         // => Top-Level routine (no jsr call before)
169         icq.add(start, new ArrayList<>());
170 
171         // LOOP!
172         while (!icq.isEmpty()) {
173             final InstructionContext u;
174             final ArrayList<InstructionContext> ec;
175             if (!DEBUG) {
176                 final int r = random.nextInt(icq.size());
177                 u = icq.getIC(r);
178                 ec = icq.getEC(r);
179                 icq.remove(r);
180             } else {
181                 u = icq.getIC(0);
182                 ec = icq.getEC(0);
183                 icq.remove(0);
184             }
185 
186             @SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
187             final ArrayList<InstructionContext> oldchain = (ArrayList<InstructionContext>) ec.clone();
188             @SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
189             final ArrayList<InstructionContext> newchain = (ArrayList<InstructionContext>) ec.clone();
190             newchain.add(u);
191 
192             if (u.getInstruction().getInstruction() instanceof RET) {
193 //System.err.println(u);
194                 // We can only follow _one_ successor, the one after the
195                 // JSR that was recently executed.
196                 final RET ret = (RET) u.getInstruction().getInstruction();
197                 final ReturnaddressType t = (ReturnaddressType) u.getOutFrame(oldchain).getLocals().get(ret.getIndex());
198                 final InstructionContext theSuccessor = cfg.contextOf(t.getTarget());
199 
200                 // Sanity check
201                 InstructionContext lastJSR = null;
202                 int skipJsr = 0;
203                 for (int ss = oldchain.size() - 1; ss >= 0; ss--) {
204                     if (skipJsr < 0) {
205                         throw new AssertionViolatedException("More RET than JSR in execution chain?!");
206                     }
207 //System.err.println("+"+oldchain.get(ss));
208                     if (oldchain.get(ss).getInstruction().getInstruction() instanceof JsrInstruction) {
209                         if (skipJsr == 0) {
210                             lastJSR = oldchain.get(ss);
211                             break;
212                         }
213                         skipJsr--;
214                     }
215                     if (oldchain.get(ss).getInstruction().getInstruction() instanceof RET) {
216                         skipJsr++;
217                     }
218                 }
219                 if (lastJSR == null) {
220                     throw new AssertionViolatedException("RET without a JSR before in ExecutionChain?! EC: '" + oldchain + "'.");
221                 }
222                 final JsrInstruction jsr = (JsrInstruction) lastJSR.getInstruction().getInstruction();
223                 if (theSuccessor != cfg.contextOf(jsr.physicalSuccessor())) {
224                     throw new AssertionViolatedException("RET '" + u.getInstruction() + "' info inconsistent: jump back to '" + theSuccessor + "' or '"
225                         + cfg.contextOf(jsr.physicalSuccessor()) + "'?");
226                 }
227 
228                 if (theSuccessor.execute(u.getOutFrame(oldchain), newchain, icv, ev)) {
229                     @SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
230                     final ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
231                     icq.add(theSuccessor, newchainClone);
232                 }
233             } else { // "not a ret"
234 
235                 // Normal successors. Add them to the queue of successors.
236                 final InstructionContext[] succs = u.getSuccessors();
237                 for (final InstructionContext v : succs) {
238                     if (v.execute(u.getOutFrame(oldchain), newchain, icv, ev)) {
239                         @SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
240                         final ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
241                         icq.add(v, newchainClone);
242                     }
243                 }
244             } // end "not a ret"
245 
246             // Exception Handlers. Add them to the queue of successors.
247             // [subroutines are never protected; mandated by JustIce]
248             final ExceptionHandler[] excHds = u.getExceptionHandlers();
249             for (final ExceptionHandler excHd : excHds) {
250                 final InstructionContext v = cfg.contextOf(excHd.getHandlerStart());
251                 // TODO: the "oldchain" and "newchain" is used to determine the subroutine
252                 // we're in (by searching for the last JSR) by the InstructionContext
253                 // implementation. Therefore, we should not use this chain mechanism
254                 // when dealing with exception handlers.
255                 // Example: a JSR with an exception handler as its successor does not
256                 // mean we're in a subroutine if we go to the exception handler.
257                 // We should address this problem later; by now we simply "cut" the chain
258                 // by using an empty chain for the exception handlers.
259                 // if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(),
260                 // new OperandStack (u.getOutFrame().getStack().maxStack(),
261                 // (exc_hds[s].getExceptionType() == null ? Type.THROWABLE : exc_hds[s].getExceptionType())) ), newchain), icv, ev) {
262                 // icq.add(v, (ArrayList) newchain.clone());
263                 if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(), new OperandStack(u.getOutFrame(oldchain).getStack().maxStack(),
264                     excHd.getExceptionType() == null ? Type.THROWABLE : excHd.getExceptionType())), new ArrayList<>(), icv, ev)) {
265                     icq.add(v, new ArrayList<>());
266                 }
267             }
268 
269         } // while (!icq.isEmpty()) END
270 
271         InstructionHandle ih = start.getInstruction();
272         do {
273             if (ih.getInstruction() instanceof ReturnInstruction && !cfg.isDead(ih)) {
274                 final InstructionContext ic = cfg.contextOf(ih);
275                 // TODO: This is buggy, we check only the top-level return instructions this way.
276                 // Maybe some maniac returns from a method when in a subroutine?
277                 final Frame f = ic.getOutFrame(new ArrayList<>());
278                 final LocalVariables lvs = f.getLocals();
279                 for (int i = 0; i < lvs.maxLocals(); i++) {
280                     if (lvs.get(i) instanceof UninitializedObjectType) {
281                         addMessage("Warning: ReturnInstruction '" + ic + "' may leave method with an uninitialized object in the local variables array '"
282                             + lvs + "'.");
283                     }
284                 }
285                 final OperandStack os = f.getStack();
286                 for (int i = 0; i < os.size(); i++) {
287                     if (os.peek(i) instanceof UninitializedObjectType) {
288                         addMessage(
289                             "Warning: ReturnInstruction '" + ic + "' may leave method with an uninitialized object on the operand stack '" + os + "'.");
290                     }
291                 }
292                 // see JVM $4.8.2
293                 Type returnedType = null;
294                 final OperandStack inStack = ic.getInFrame().getStack();
295                 if (inStack.size() >= 1) {
296                     returnedType = inStack.peek();
297                 } else {
298                     returnedType = Type.VOID;
299                 }
300 
301                 if (returnedType != null) {
302                     if (returnedType instanceof ReferenceType) {
303                         try {
304                             if (!((ReferenceType) returnedType).isCastableTo(m.getReturnType())) {
305                                 invalidReturnTypeError(returnedType, m);
306                             }
307                         } catch (final ClassNotFoundException e) {
308                             // Don't know what to do now, so raise RuntimeException
309                             throw new IllegalArgumentException(e);
310                         }
311                     } else if (!returnedType.equals(m.getReturnType().normalizeForStackOrLocal())) {
312                         invalidReturnTypeError(returnedType, m);
313                     }
314                 }
315             }
316         } while ((ih = ih.getNext()) != null);
317 
318     }
319 
320     /**
321      * Pass 3b implements the data flow analysis as described in the Java Virtual Machine Specification, Second Edition.
322      * Later versions will use LocalVariablesInfo objects to verify if the verifier-inferred types and the class file's
323      * debug information (LocalVariables attributes) match [TODO].
324      *
325      * @see org.apache.bcel.verifier.statics.LocalVariablesInfo
326      * @see org.apache.bcel.verifier.statics.Pass2Verifier#getLocalVariablesInfo(int)
327      */
328     @Override
329     public VerificationResult do_verify() {
330         if (!myOwner.doPass3a(methodNo).equals(VerificationResult.VR_OK)) {
331             return VerificationResult.VR_NOTYET;
332         }
333 
334         // Pass 3a ran before, so it's safe to assume the JavaClass object is
335         // in the BCEL repository.
336         final JavaClass jc;
337         try {
338             jc = Repository.lookupClass(myOwner.getClassName());
339         } catch (final ClassNotFoundException e) {
340             // FIXME: maybe not the best way to handle this
341             throw new AssertionViolatedException("Missing class: " + e, e);
342         }
343 
344         final ConstantPoolGen constantPoolGen = new ConstantPoolGen(jc.getConstantPool());
345         // Init Visitors
346         final InstConstraintVisitor icv = new InstConstraintVisitor();
347         icv.setConstantPoolGen(constantPoolGen);
348 
349         final ExecutionVisitor ev = new ExecutionVisitor();
350         ev.setConstantPoolGen(constantPoolGen);
351 
352         final Method[] methods = jc.getMethods(); // Method no "methodNo" exists, we ran Pass3a before on it!
353 
354         try {
355 
356             final MethodGen mg = new MethodGen(methods[methodNo], myOwner.getClassName(), constantPoolGen);
357 
358             icv.setMethodGen(mg);
359 
360             ////////////// DFA BEGINS HERE ////////////////
361             if (!(mg.isAbstract() || mg.isNative())) { // IF mg HAS CODE (See pass 2)
362 
363                 final ControlFlowGraph cfg = new ControlFlowGraph(mg);
364 
365                 // Build the initial frame situation for this method.
366                 final Frame f = new Frame(mg.getMaxLocals(), mg.getMaxStack());
367                 if (!mg.isStatic()) {
368                     if (mg.getName().equals(Const.CONSTRUCTOR_NAME)) {
369                         Frame.setThis(new UninitializedObjectType(ObjectType.getInstance(jc.getClassName())));
370                         f.getLocals().set(0, Frame.getThis());
371                     } else {
372                         Frame.setThis(null);
373                         f.getLocals().set(0, ObjectType.getInstance(jc.getClassName()));
374                     }
375                 }
376                 final Type[] argtypes = mg.getArgumentTypes();
377                 int twoslotoffset = 0;
378                 for (int j = 0; j < argtypes.length; j++) {
379                     if (argtypes[j] == Type.SHORT || argtypes[j] == Type.BYTE || argtypes[j] == Type.CHAR || argtypes[j] == Type.BOOLEAN) {
380                         argtypes[j] = Type.INT;
381                     }
382                     f.getLocals().set(twoslotoffset + j + (mg.isStatic() ? 0 : 1), argtypes[j]);
383                     if (argtypes[j].getSize() == 2) {
384                         twoslotoffset++;
385                         f.getLocals().set(twoslotoffset + j + (mg.isStatic() ? 0 : 1), Type.UNKNOWN);
386                     }
387                 }
388                 circulationPump(mg, cfg, cfg.contextOf(mg.getInstructionList().getStart()), f, icv, ev);
389             }
390         } catch (final VerifierConstraintViolatedException ce) {
391             ce.extendMessage("Constraint violated in method '" + methods[methodNo] + "':\n", "");
392             return new VerificationResult(VerificationResult.VERIFIED_REJECTED, ce.getMessage());
393         } catch (final RuntimeException re) {
394             // These are internal errors
395 
396             final StringWriter sw = new StringWriter();
397             final PrintWriter pw = new PrintWriter(sw);
398             re.printStackTrace(pw);
399 
400             throw new AssertionViolatedException("Some RuntimeException occurred while verify()ing class '" + jc.getClassName() + "', method '"
401                 + methods[methodNo] + "'. Original RuntimeException's stack trace:\n---\n" + sw + "---\n", re);
402         }
403         return VerificationResult.VR_OK;
404     }
405 
406     /** Returns the method number as supplied when instantiating. */
407     public int getMethodNo() {
408         return methodNo;
409     }
410 
411     /**
412      * Throws an exception indicating the returned type is not compatible with the return type of the given method.
413      *
414      * @param returnedType the type of the returned expression
415      * @param m the method we are processing
416      * @throws StructuralCodeConstraintException always
417      * @since 6.0
418      */
419     public void invalidReturnTypeError(final Type returnedType, final MethodGen m) {
420         throw new StructuralCodeConstraintException("Returned type " + returnedType + " does not match Method's return type " + m.getReturnType());
421     }
422 }