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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   * @see #do_verify()
57   */
58  
59  public final class Pass3bVerifier extends PassVerifier{
60      /* TODO:    Throughout pass 3b, upper halves of LONG and DOUBLE
61                          are represented by Type.UNKNOWN. This should be changed
62                          in favour of LONG_Upper and DOUBLE_Upper as in pass 2. */
63  
64      /**
65       * An InstructionContextQueue is a utility class that holds
66       * (InstructionContext, ArrayList) pairs in a Queue data structure.
67       * This is used to hold information about InstructionContext objects
68       * externally --- i.e. that information is not saved inside the
69       * InstructionContext object itself. This is useful to save the
70       * execution path of the symbolic execution of the
71       * Pass3bVerifier - this is not information
72       * that belongs into the InstructionContext object itself.
73       * Only at "execute()"ing
74       * time, an InstructionContext object will get the current information
75       * we have about its symbolic execution predecessors.
76       */
77      private static final class InstructionContextQueue {
78          // The following two fields together represent the queue.
79          /** The first elements from pairs in the queue. */
80          private final List<InstructionContext> ics = new Vector<>();
81          /** The second elements from pairs in the queue. */
82          private final List<ArrayList<InstructionContext>> ecs = new Vector<>();
83  
84          /**
85           * Adds an (InstructionContext, ExecutionChain) pair to this queue.
86           *
87           * @param ic the InstructionContext
88           * @param executionChain the ExecutionChain
89           */
90          public void add(final InstructionContext ic, final ArrayList<InstructionContext> executionChain) {
91              ics.add(ic);
92              ecs.add(executionChain);
93          }
94  
95          /**
96           * Tests if InstructionContext queue is empty.
97           *
98           * @return true if the InstructionContext queue is empty.
99           */
100         public boolean isEmpty() {
101             return ics.isEmpty();
102         }
103 
104         /**
105          * Removes a specific (InstructionContext, ExecutionChain) pair from their respective queues.
106          *
107          * @param i the index of the items to be removed
108          */
109         public void remove(final int i) {
110             ics.remove(i);
111             ecs.remove(i);
112         }
113 
114         /**
115          * Gets a specific InstructionContext from the queue.
116          *
117          * @param i the index of the item to be fetched
118          * @return the indicated InstructionContext
119          */
120         public InstructionContext getIC(final int i) {
121             return ics.get(i);
122         }
123 
124         /**
125          * Gets a specific ExecutionChain from the queue.
126          *
127          * @param i the index of the item to be fetched
128          * @return the indicated ExecutionChain
129          */
130         public ArrayList<InstructionContext> getEC(final int i) {
131             return ecs.get(i);
132         }
133 
134         /**
135          * Gets the size of the InstructionContext queue.
136          *
137          * @return the size of the InstructionQueue
138          */
139         public int size() {
140             return ics.size();
141         }
142     } // end Inner Class InstructionContextQueue
143 
144     /** In DEBUG mode, the verification algorithm is not randomized. */
145     private static final boolean DEBUG = true;
146 
147     /** The Verifier that created this. */
148     private final Verifier myOwner;
149 
150     /** The method number to verify. */
151     private final int methodNo;
152 
153     /**
154      * This class should only be instantiated by a Verifier.
155      *
156      * @see org.apache.bcel.verifier.Verifier
157      */
158     public Pass3bVerifier(final Verifier owner, final int method_no) {
159         myOwner = owner;
160         this.methodNo = method_no;
161     }
162 
163     /**
164      * Whenever the outgoing frame
165      * situation of an InstructionContext changes, all its successors are
166      * put [back] into the queue [as if they were unvisited].
167      * The proof of termination is about the existence of a
168      * fix point of frame merging.
169      */
170     private void circulationPump(final MethodGen m,final ControlFlowGraph cfg, final InstructionContext start,
171             final Frame vanillaFrame, final InstConstraintVisitor icv, final ExecutionVisitor ev) {
172         final Random random = new Random();
173         final InstructionContextQueue icq = new InstructionContextQueue();
174 
175         start.execute(vanillaFrame, new ArrayList<InstructionContext>(), icv, ev);
176         // new ArrayList() <=>    no Instruction was executed before
177         //                                    => Top-Level routine (no jsr call before)
178         icq.add(start, new ArrayList<InstructionContext>());
179 
180         // LOOP!
181         while (!icq.isEmpty()) {
182             InstructionContext u;
183             ArrayList<InstructionContext> ec;
184             if (!DEBUG) {
185                 final int r = random.nextInt(icq.size());
186                 u = icq.getIC(r);
187                 ec = icq.getEC(r);
188                 icq.remove(r);
189             }
190             else{
191                 u  = icq.getIC(0);
192                 ec = icq.getEC(0);
193                 icq.remove(0);
194             }
195 
196             @SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
197             final
198             ArrayList<InstructionContext> oldchain = (ArrayList<InstructionContext>) (ec.clone());
199             @SuppressWarnings("unchecked") // ec is of type ArrayList<InstructionContext>
200             final
201             ArrayList<InstructionContext> newchain = (ArrayList<InstructionContext>) (ec.clone());
202             newchain.add(u);
203 
204             if ((u.getInstruction().getInstruction()) instanceof RET) {
205 //System.err.println(u);
206                 // We can only follow _one_ successor, the one after the
207                 // JSR that was recently executed.
208                 final REThref="../../../../../org/apache/bcel/generic/RET.html#RET">RET ret = (RET) (u.getInstruction().getInstruction());
209                 final ReturnaddressType../../../org/apache/bcel/generic/ReturnaddressType.html#ReturnaddressType">ReturnaddressType t = (ReturnaddressType) u.getOutFrame(oldchain).getLocals().get(ret.getIndex());
210                 final InstructionContext theSuccessor = cfg.contextOf(t.getTarget());
211 
212                 // Sanity check
213                 InstructionContext lastJSR = null;
214                 int skip_jsr = 0;
215                 for (int ss=oldchain.size()-1; ss >= 0; ss--) {
216                     if (skip_jsr < 0) {
217                         throw new AssertionViolatedException("More RET than JSR in execution chain?!");
218                     }
219 //System.err.println("+"+oldchain.get(ss));
220                     if ((oldchain.get(ss)).getInstruction().getInstruction() instanceof JsrInstruction) {
221                         if (skip_jsr == 0) {
222                             lastJSR = oldchain.get(ss);
223                             break;
224                         }
225                         skip_jsr--;
226                     }
227                     if ((oldchain.get(ss)).getInstruction().getInstruction() instanceof RET) {
228                         skip_jsr++;
229                     }
230                 }
231                 if (lastJSR == null) {
232                     throw new AssertionViolatedException("RET without a JSR before in ExecutionChain?! EC: '"+oldchain+"'.");
233                 }
234                 final JsrInstruction/../../../org/apache/bcel/generic/JsrInstruction.html#JsrInstruction">JsrInstruction jsr = (JsrInstruction) (lastJSR.getInstruction().getInstruction());
235                 if ( theSuccessor != (cfg.contextOf(jsr.physicalSuccessor())) ) {
236                     throw new AssertionViolatedException("RET '"+u.getInstruction()+"' info inconsistent: jump back to '"+
237                         theSuccessor+"' or '"+cfg.contextOf(jsr.physicalSuccessor())+"'?");
238                 }
239 
240                 if (theSuccessor.execute(u.getOutFrame(oldchain), newchain, icv, ev)) {
241                     @SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
242                     final
243                     ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
244                     icq.add(theSuccessor, newchainClone);
245                 }
246             }
247             else{// "not a ret"
248 
249                 // Normal successors. Add them to the queue of successors.
250                 final InstructionContext[] succs = u.getSuccessors();
251                 for (final InstructionContext v : succs) {
252                     if (v.execute(u.getOutFrame(oldchain), newchain, icv, ev)) {
253                         @SuppressWarnings("unchecked") // newchain is already of type ArrayList<InstructionContext>
254                         final
255                         ArrayList<InstructionContext> newchainClone = (ArrayList<InstructionContext>) newchain.clone();
256                         icq.add(v, newchainClone);
257                     }
258                 }
259             }// end "not a ret"
260 
261             // Exception Handlers. Add them to the queue of successors.
262             // [subroutines are never protected; mandated by JustIce]
263             final ExceptionHandler[] exc_hds = u.getExceptionHandlers();
264             for (final ExceptionHandler exc_hd : exc_hds) {
265                 final InstructionContext v = cfg.contextOf(exc_hd.getHandlerStart());
266                 // TODO: the "oldchain" and "newchain" is used to determine the subroutine
267                 // we're in (by searching for the last JSR) by the InstructionContext
268                 // implementation. Therefore, we should not use this chain mechanism
269                 // when dealing with exception handlers.
270                 // Example: a JSR with an exception handler as its successor does not
271                 // mean we're in a subroutine if we go to the exception handler.
272                 // We should address this problem later; by now we simply "cut" the chain
273                 // by using an empty chain for the exception handlers.
274                 //if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(),
275                 // new OperandStack (u.getOutFrame().getStack().maxStack(),
276                 // (exc_hds[s].getExceptionType()==null? Type.THROWABLE : exc_hds[s].getExceptionType())) ), newchain), icv, ev) {
277                     //icq.add(v, (ArrayList) newchain.clone());
278                 if (v.execute(new Frame(u.getOutFrame(oldchain).getLocals(),
279                         new OperandStack (u.getOutFrame(oldchain).getStack().maxStack(),
280                         exc_hd.getExceptionType()==null? Type.THROWABLE : exc_hd.getExceptionType())),
281                         new ArrayList<InstructionContext>(), icv, ev)) {
282                     icq.add(v, new ArrayList<InstructionContext>());
283                 }
284             }
285 
286         }// while (!icq.isEmpty()) END
287 
288         InstructionHandle ih = start.getInstruction();
289         do{
290             if ((ih.getInstruction() instanceof ReturnInstruction) && (!(cfg.isDead(ih)))) {
291                 final InstructionContext ic = cfg.contextOf(ih);
292                 // TODO: This is buggy, we check only the top-level return instructions this way.
293                 // Maybe some maniac returns from a method when in a subroutine?
294                 final Frame f = ic.getOutFrame(new ArrayList<InstructionContext>());
295                 final LocalVariables lvs = f.getLocals();
296                 for (int i=0; i<lvs.maxLocals(); i++) {
297                     if (lvs.get(i) instanceof UninitializedObjectType) {
298                         this.addMessage("Warning: ReturnInstruction '"+ic+
299                             "' may leave method with an uninitialized object in the local variables array '"+lvs+"'.");
300                     }
301                 }
302                 final OperandStack os = f.getStack();
303                 for (int i=0; i<os.size(); i++) {
304                     if (os.peek(i) instanceof UninitializedObjectType) {
305                         this.addMessage("Warning: ReturnInstruction '"+ic+
306                             "' may leave method with an uninitialized object on the operand stack '"+os+"'.");
307                     }
308                 }
309                 //see JVM $4.8.2
310                 Type returnedType = null;
311                 final OperandStack inStack = ic.getInFrame().getStack();
312                 if (inStack.size() >= 1) {
313                     returnedType = inStack.peek();
314                 } else {
315                     returnedType = Type.VOID;
316                 }
317 
318                 if (returnedType != null) {
319                     if (returnedType instanceof ReferenceType) {
320                         try {
321                             if (!((ReferenceType) returnedType).isCastableTo(m.getReturnType())) {
322                                 invalidReturnTypeError(returnedType, m);
323                             }
324                         } catch (final ClassNotFoundException e) {
325                             // Don't know what do do now, so raise RuntimeException
326                             throw new IllegalArgumentException(e);
327                         }
328                     } else if (!returnedType.equals(m.getReturnType().normalizeForStackOrLocal())) {
329                         invalidReturnTypeError(returnedType, m);
330                     }
331                 }
332             }
333         } while ((ih = ih.getNext()) != null);
334 
335      }
336 
337     /**
338      * Throws an exception indicating the returned type is not compatible with the return type of the given method.
339      *
340      * @param returnedType the type of the returned expression
341      * @param m the method we are processing
342      * @throws StructuralCodeConstraintException always
343      * @since 6.0
344      */
345     public void invalidReturnTypeError(final Type returnedType, final MethodGen m) {
346         throw new StructuralCodeConstraintException(
347             "Returned type "+returnedType+" does not match Method's return type "+m.getReturnType());
348     }
349 
350     /**
351      * Pass 3b implements the data flow analysis as described in the Java Virtual
352      * Machine Specification, Second Edition.
353      * Later versions will use LocalVariablesInfo objects to verify if the
354      * verifier-inferred types and the class file's debug information (LocalVariables
355      * attributes) match [TODO].
356      *
357      * @see org.apache.bcel.verifier.statics.LocalVariablesInfo
358      * @see org.apache.bcel.verifier.statics.Pass2Verifier#getLocalVariablesInfo(int)
359      */
360     @Override
361     public VerificationResult do_verify() {
362         if (! myOwner.doPass3a(methodNo).equals(VerificationResult.VR_OK)) {
363             return VerificationResult.VR_NOTYET;
364         }
365 
366         // Pass 3a ran before, so it's safe to assume the JavaClass object is
367         // in the BCEL repository.
368         JavaClass jc;
369         try {
370             jc = Repository.lookupClass(myOwner.getClassName());
371         } catch (final ClassNotFoundException e) {
372             // FIXME: maybe not the best way to handle this
373             throw new AssertionViolatedException("Missing class: " + e, e);
374         }
375 
376         final ConstantPoolGenl#ConstantPoolGen">ConstantPoolGen constantPoolGen = new ConstantPoolGen(jc.getConstantPool());
377         // Init Visitors
378         final InstConstraintVisitorInstConstraintVisitor.html#InstConstraintVisitor">InstConstraintVisitor icv = new InstConstraintVisitor();
379         icv.setConstantPoolGen(constantPoolGen);
380 
381         final ExecutionVisitorurals/ExecutionVisitor.html#ExecutionVisitor">ExecutionVisitor ev = new ExecutionVisitor();
382         ev.setConstantPoolGen(constantPoolGen);
383 
384         final Method[] methods = jc.getMethods(); // Method no "methodNo" exists, we ran Pass3a before on it!
385 
386         try{
387 
388             final MethodGenMethodGen.html#MethodGen">MethodGen mg = new MethodGen(methods[methodNo], myOwner.getClassName(), constantPoolGen);
389 
390             icv.setMethodGen(mg);
391 
392             ////////////// DFA BEGINS HERE ////////////////
393             if (! (mg.isAbstract() || mg.isNative()) ) { // IF mg HAS CODE (See pass 2)
394 
395                 final ControlFlowGraphrals/ControlFlowGraph.html#ControlFlowGraph">ControlFlowGraph cfg = new ControlFlowGraph(mg);
396 
397                 // Build the initial frame situation for this method.
398                 final Frameifier/structurals/Frame.html#Frame">Frame f = new Frame(mg.getMaxLocals(),mg.getMaxStack());
399                 if ( !mg.isStatic() ) {
400                     if (mg.getName().equals(Const.CONSTRUCTOR_NAME)) {
401                         Frame.setThis(new UninitializedObjectType(ObjectType.getInstance(jc.getClassName())));
402                         f.getLocals().set(0, Frame.getThis());
403                     }
404                     else{
405                         Frame.setThis(null);
406                         f.getLocals().set(0, ObjectType.getInstance(jc.getClassName()));
407                     }
408                 }
409                 final Type[] argtypes = mg.getArgumentTypes();
410                 int twoslotoffset = 0;
411                 for (int j=0; j<argtypes.length; j++) {
412                     if (argtypes[j] == Type.SHORT || argtypes[j] == Type.BYTE ||
413                         argtypes[j] == Type.CHAR || argtypes[j] == Type.BOOLEAN) {
414                         argtypes[j] = Type.INT;
415                     }
416                     f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), argtypes[j]);
417                     if (argtypes[j].getSize() == 2) {
418                         twoslotoffset++;
419                         f.getLocals().set(twoslotoffset + j + (mg.isStatic()?0:1), Type.UNKNOWN);
420                     }
421                 }
422                 circulationPump(mg,cfg, cfg.contextOf(mg.getInstructionList().getStart()), f, icv, ev);
423             }
424         }
425         catch (final VerifierConstraintViolatedException ce) {
426             ce.extendMessage("Constraint violated in method '"+methods[methodNo]+"':\n","");
427             return new VerificationResult(VerificationResult.VERIFIED_REJECTED, ce.getMessage());
428         }
429         catch (final RuntimeException re) {
430             // These are internal errors
431 
432             final StringWriter sw = new StringWriter();
433             final PrintWriter pw = new PrintWriter(sw);
434             re.printStackTrace(pw);
435 
436             throw new AssertionViolatedException("Some RuntimeException occured while verify()ing class '"+jc.getClassName()+
437                 "', method '"+methods[methodNo]+"'. Original RuntimeException's stack trace:\n---\n"+sw+"---\n", re);
438         }
439         return VerificationResult.VR_OK;
440     }
441 
442     /** Returns the method number as supplied when instantiating. */
443     public int getMethodNo() {
444         return methodNo;
445     }
446 }