001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 * 017 */ 018package org.apache.bcel.verifier.structurals; 019 020 021import java.io.PrintWriter; 022import java.io.StringWriter; 023import java.util.ArrayList; 024import java.util.List; 025import java.util.Random; 026import java.util.Vector; 027 028import org.apache.bcel.Const; 029import org.apache.bcel.Repository; 030import org.apache.bcel.classfile.JavaClass; 031import org.apache.bcel.classfile.Method; 032import org.apache.bcel.generic.ConstantPoolGen; 033import org.apache.bcel.generic.InstructionHandle; 034import org.apache.bcel.generic.JsrInstruction; 035import org.apache.bcel.generic.MethodGen; 036import org.apache.bcel.generic.ObjectType; 037import org.apache.bcel.generic.RET; 038import org.apache.bcel.generic.ReferenceType; 039import org.apache.bcel.generic.ReturnInstruction; 040import org.apache.bcel.generic.ReturnaddressType; 041import org.apache.bcel.generic.Type; 042import org.apache.bcel.verifier.PassVerifier; 043import org.apache.bcel.verifier.VerificationResult; 044import org.apache.bcel.verifier.Verifier; 045import org.apache.bcel.verifier.exc.AssertionViolatedException; 046import org.apache.bcel.verifier.exc.StructuralCodeConstraintException; 047import org.apache.bcel.verifier.exc.VerifierConstraintViolatedException; 048 049/** 050 * This PassVerifier verifies a method of class file according to pass 3, 051 * so-called structural verification as described in The Java Virtual Machine 052 * Specification, 2nd edition. 053 * More detailed information is to be found at the do_verify() method's 054 * documentation. 055 * 056 * @see #do_verify() 057 */ 058 059public final class Pass3bVerifier extends PassVerifier{ 060 /* TODO: Throughout pass 3b, upper halves of LONG and DOUBLE 061 are represented by Type.UNKNOWN. This should be changed 062 in favour of LONG_Upper and DOUBLE_Upper as in pass 2. */ 063 064 /** 065 * An InstructionContextQueue is a utility class that holds 066 * (InstructionContext, ArrayList) pairs in a Queue data structure. 067 * This is used to hold information about InstructionContext objects 068 * externally --- i.e. that information is not saved inside the 069 * InstructionContext object itself. This is useful to save the 070 * execution path of the symbolic execution of the 071 * Pass3bVerifier - this is not information 072 * that belongs into the InstructionContext object itself. 073 * Only at "execute()"ing 074 * time, an InstructionContext object will get the current information 075 * we have about its symbolic execution predecessors. 076 */ 077 private static final class InstructionContextQueue { 078 // The following two fields together represent the queue. 079 /** The first elements from pairs in the queue. */ 080 private final List<InstructionContext> ics = new Vector<>(); 081 /** The second elements from pairs in the queue. */ 082 private final List<ArrayList<InstructionContext>> ecs = new Vector<>(); 083 084 /** 085 * Adds an (InstructionContext, ExecutionChain) pair to this queue. 086 * 087 * @param ic the InstructionContext 088 * @param executionChain the ExecutionChain 089 */ 090 public void add(final InstructionContext ic, final ArrayList<InstructionContext> executionChain) { 091 ics.add(ic); 092 ecs.add(executionChain); 093 } 094 095 /** 096 * Tests if InstructionContext queue is empty. 097 * 098 * @return true if the InstructionContext queue is empty. 099 */ 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 RET ret = (RET) (u.getInstruction().getInstruction()); 209 final 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 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 ConstantPoolGen constantPoolGen = new ConstantPoolGen(jc.getConstantPool()); 377 // Init Visitors 378 final InstConstraintVisitor icv = new InstConstraintVisitor(); 379 icv.setConstantPoolGen(constantPoolGen); 380 381 final 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 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 ControlFlowGraph cfg = new ControlFlowGraph(mg); 396 397 // Build the initial frame situation for this method. 398 final 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}