Beispiel #1
0
static bool IsVariableArgumentFormat(AST::Ptr t, AbsRegion &index) {
    if (t->getID() != AST::V_RoseAST) {
        return false;
    }
    RoseAST::Ptr rt = boost::static_pointer_cast<RoseAST>(t);
    if (rt->val().op != ROSEOperation::addOp) {
        return false;
    }
    if (rt->child(0)->getID() != AST::V_ConstantAST || rt->child(1)->getID() != AST::V_RoseAST) {
        return false;
    }
    RoseAST::Ptr c1 = boost::static_pointer_cast<RoseAST>(rt->child(1));
    if (c1->val().op == ROSEOperation::addOp) {
        if (c1->child(0)->getID() == AST::V_RoseAST && c1->child(1)->getID() == AST::V_ConstantAST) {
	    RoseAST::Ptr lc = boost::static_pointer_cast<RoseAST>(c1->child(0));
	    ConstantAST::Ptr rc = boost::static_pointer_cast<ConstantAST>(c1->child(1));
	    if (lc->val().op == ROSEOperation::invertOp && rc->val().val == 1) {
	        return IsIndexing(lc->child(0), index);
	    }
	}
	return false;
    }
    return IsIndexing(rt->child(1), index);

}
Beispiel #2
0
AST::Ptr DeepCopyAnAST(AST::Ptr ast) {
    if (ast->getID() == AST::V_RoseAST) {
        RoseAST::Ptr roseAST = boost::static_pointer_cast<RoseAST>(ast);
	AST::Children kids;
        unsigned totalChildren = ast->numChildren();
	for (unsigned i = 0 ; i < totalChildren; ++i) {
	    kids.push_back(DeepCopyAnAST(ast->child(i)));
	}
	return RoseAST::create(ROSEOperation(roseAST->val()), kids);
    } else if (ast->getID() == AST::V_VariableAST) {
        VariableAST::Ptr varAST = boost::static_pointer_cast<VariableAST>(ast);
	return VariableAST::create(Variable(varAST->val()));
    } else if (ast->getID() == AST::V_ConstantAST) {
        ConstantAST::Ptr constAST = boost::static_pointer_cast<ConstantAST>(ast);
	return ConstantAST::create(Constant(constAST->val()));
    } else if (ast->getID() == AST::V_BottomAST) {
        BottomAST::Ptr bottomAST = boost::static_pointer_cast<BottomAST>(ast);
	return BottomAST::create(bottomAST->val());
    }
    fprintf(stderr, "ast type %d, %s\n", ast->getID(), ast->format().c_str());
    assert(0);
	return AST::Ptr();
}
Beispiel #3
0
AST::Ptr ComparisonVisitor::visit(DataflowAPI::RoseAST *ast) {
    // For cmp type instruction setting zf
    // Looking like <eqZero?>(<add>(<V([x86_64::rbx])>,<Imm:8>,),)
    // Assuming ast has been simplified
    if (ast->val().op == ROSEOperation::equalToZeroOp) {
        bool minuendIsZero = true;
        AST::Ptr child = ast->child(0);	
	if (child->getID() == AST::V_RoseAST) {
	    RoseAST::Ptr childRose = boost::static_pointer_cast<RoseAST>(child);
	    if (childRose->val().op == ROSEOperation::addOp) {
	        minuendIsZero = false;
	        subtrahend = childRose->child(0);
		minuend = childRose->child(1);
		// If the minuend is a constant, then
		// the minuend is currently in its two-complement form
		if (minuend->getID() == AST::V_ConstantAST) {
		    ConstantAST::Ptr constAST = boost::static_pointer_cast<ConstantAST>(minuend);
		    uint64_t val = constAST->val().val;
		    int size = constAST->val().size;
		    if (size < 64) 
		        val = ((~val)+ 1) & ((1ULL << size) - 1);
		    else if (size == 64)
		        val = (~val) + 1;
		    else
		        parsing_printf("WARNING: constant bit size %d exceeds 64!\n", size);
		    minuend = ConstantAST::create(Constant(val, size));
		} else if (minuend->getID() == AST::V_RoseAST) {
		    RoseAST::Ptr sub = boost::static_pointer_cast<RoseAST>(minuend);
		    minuend = AST::Ptr();
		    if (sub->val().op == ROSEOperation::addOp && sub->child(0)->getID() == AST::V_RoseAST) {
		        sub = boost::static_pointer_cast<RoseAST>(sub->child(0));
			if (sub->val().op == ROSEOperation::invertOp) {
			    // Otherwise, the minuend ast is in the form of add(invert(minuend), 1)
  		            // Need to extract the real minuend
		             minuend = sub->child(0);
			}
		    }
		}
	    } 	
	} 
	if (minuendIsZero) {
            // The minuend is 0, thus the add operation is subsume.
             subtrahend = ast->child(0);
	     minuend = ConstantAST::create(Constant(0));
	}
    }
    return AST::Ptr();
}
Beispiel #4
0
AST::Ptr SubstituteAnAST(AST::Ptr ast, const BoundFact::AliasMap &aliasMap) {
    for (auto ait = aliasMap.begin(); ait != aliasMap.end(); ++ait)
        if (*ast == *(ait->first)) {
	    return ait->second;
	}
    unsigned totalChildren = ast->numChildren();
    for (unsigned i = 0 ; i < totalChildren; ++i) {
        ast->setChild(i, SubstituteAnAST(ast->child(i), aliasMap));
    }
    if (ast->getID() == AST::V_VariableAST) {
        // If this variable is not in the aliasMap yet,
	// this variable is from the input.
        VariableAST::Ptr varAST = boost::static_pointer_cast<VariableAST>(ast);
	return VariableAST::create(Variable(varAST->val().reg, 1));
    }
    return ast;

}
Beispiel #5
0
void BoundFactsCalculator::CalcTransferFunction(Node::Ptr curNode, BoundFact *newFact){
    SliceNode::Ptr node = boost::static_pointer_cast<SliceNode>(curNode);
    if (!node->assign()) return;
    if (node->assign() && node->assign()->out().absloc().type() == Absloc::Register &&
	    (node->assign()->out().absloc().reg() == x86::zf || node->assign()->out().absloc().reg() == x86_64::zf)) {
	    // zf should be only predecessor of this node
        parsing_printf("\t\tThe predecessor node is zf assignment!\n");
	newFact->SetPredicate(node->assign(), ExpandAssignment(node->assign()) );
	return;
    }
    entryID id = node->assign()->insn()->getOperation().getID();
    // The predecessor is not a conditional jump,
    // then we can determine buond fact based on the src assignment
    parsing_printf("\t\tThe predecessor node is normal node\n");
    parsing_printf("\t\t\tentry id %d\n", id);

    AbsRegion &ar = node->assign()->out();
    Instruction::Ptr insn = node->assign()->insn();
    pair<AST::Ptr, bool> expandRet = ExpandAssignment(node->assign());

    if (expandRet.first == NULL) {
        parsing_printf("\t\t\t No semantic support for this instruction. Assume it does not affect jump target calculation. Ignore it (Treat as identity function) except for ptest. ptest should kill the current predicate\n");
	if (id == e_ptest) {
	    parsing_printf("\t\t\t\tptest instruction, kill predciate.\n");
	    newFact->pred.valid = false;
	}
	return;
    } else {
        parsing_printf("\tAST: %s\n", expandRet.first->format().c_str());
    }

    AST::Ptr calculation = expandRet.first;
    BoundCalcVisitor bcv(*newFact, node->block(), handleOneByteRead);
    calculation->accept(&bcv);
    AST::Ptr outAST;
    // If the instruction writes memory,
    // we need the AST that represents the memory access and the address.
    // When the AbsRegion represents memory,
    // the generator of the AbsRegion is set to be the AST that represents
    // the memory address during symbolic expansion.
    // In other cases, if the AbsRegion represents a register,
    // the generator is not set.
    if (ar.generator() != NULL)
        outAST = SimplifyAnAST(RoseAST::create(ROSEOperation(ROSEOperation::derefOp, ar.size()), ar.generator()), node->assign()->insn()->size());
    else
        outAST = VariableAST::create(Variable(ar));
/*
 * Naively, bsf and bsr produces a bound from 0 to the number of bits of the source operands.
 * In pratice, especially in libc, the real bound is usually smaller than the size of the source operand.
 * Ex 1: shl    %cl,%edx
 *       bsf    %rdx,%rcx
 * Here rcx is in range [0,31] rather than [0,63] even though rdx has 64 bits.
 *
 * Ex 2: pmovmskb %xmm0,%edx
 *       bsf    %rdx, %rdx
 * Here rdx is in range[0,15] because pmovmskb only sets the least significat 16 bits
 * In addition, overapproximation of the bound can lead to bogus control flow
 * that causes overlapping blocks or function.
 * It is important to further anaylze the operand in bsf rather than directly conclude the bound
    if (id == e_bsf || id == e_bsr) {
	int size = node->assign()->insn()->getOperand(0).getValue()->size();
	newFact->GenFact(outAST, new BoundValue(StridedInterval(1,0, size * 8 - 1)), false);
        parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
	newFact->Print();
	return;

    }
*/
    if (id == e_xchg) {
        newFact->SwapFact(calculation, outAST);
        parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
	newFact->Print();
	return;
    }

    if (id == e_push) {
         if (calculation->getID() == AST::V_ConstantAST) {
	     ConstantAST::Ptr c = boost::static_pointer_cast<ConstantAST>(calculation);
	     newFact->PushAConst(c->val().val);
	     parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
	     newFact->Print();
	     return;
	 }
    }

    if (id == e_pop) {
        if (newFact->PopAConst(outAST)) {
	     parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
	     newFact->Print();
	     return;
        }
    }

    // Assume all SETxx entry ids are contiguous
    if (id >= e_setb && id <= e_setz) {
        newFact->GenFact(outAST, new BoundValue(StridedInterval(1,0,1)), false);
	parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
	newFact->Print();
	return;
    }


    if (bcv.IsResultBounded(calculation)) {
        parsing_printf("\t\t\tGenerate bound fact for %s\n", outAST->format().c_str());
	newFact->GenFact(outAST, new BoundValue(*bcv.GetResultBound(calculation)), false);
    }
    else {
        parsing_printf("\t\t\tKill bound fact for %s\n", outAST->format().c_str());
	newFact->KillFact(outAST, false);
    }
    if (calculation->getID() == AST::V_VariableAST) {
        // We only track alising between registers
	parsing_printf("\t\t\t%s and %s are equal\n", calculation->format().c_str(), outAST->format().c_str());
	newFact->InsertRelation(calculation, outAST, BoundFact::Equal);
    }
    newFact->AdjustPredicate(outAST, calculation);

    // Now try to track all aliasing.
    // Currently, all variables in the slice are presented as an AST
    // consists of input variables to the slice (the variables that
    // we do not the sources of their values).
    newFact->TrackAlias(DeepCopyAnAST(calculation), outAST);

    // Apply tracking relations to the calculation to generate a
    // potentially stricter bound
    BoundValue *strictValue = newFact->ApplyRelations(outAST);
    if (strictValue != NULL) {
        parsing_printf("\t\t\tGenerate stricter bound fact for %s\n", outAST->format().c_str());
	newFact->GenFact(outAST, strictValue, false);
    }
    parsing_printf("\t\t\tCalculating transfer function: Output facts\n");
    newFact->Print();

}
Beispiel #6
0
AST::Ptr SimplifyRoot(AST::Ptr ast, Address addr) {
    if (ast->getID() == AST::V_RoseAST) {
        RoseAST::Ptr roseAST = boost::static_pointer_cast<RoseAST>(ast); 
	
	switch (roseAST->val().op) {
	    case ROSEOperation::invertOp:
	        if (roseAST->child(0)->getID() == AST::V_RoseAST) {
		    RoseAST::Ptr child = boost::static_pointer_cast<RoseAST>(roseAST->child(0));
		    if (child->val().op == ROSEOperation::invertOp) return child->child(0);
		} else if (roseAST->child(0)->getID() == AST::V_ConstantAST) {
		    ConstantAST::Ptr child = boost::static_pointer_cast<ConstantAST>(roseAST->child(0));
		    size_t size = child->val().size;
		    uint64_t val = child->val().val;
		    if (size < 64) {
		        uint64_t mask = (1ULL << size) - 1;
		        val = (~val) & mask;
		    } else
		        val = ~val;
		    return ConstantAST::create(Constant(val, size));
		}
		break;
	    case ROSEOperation::extendMSBOp:
	    case ROSEOperation::extractOp:
	    case ROSEOperation::signExtendOp:
	    case ROSEOperation::concatOp:
	        return roseAST->child(0);

	    case ROSEOperation::addOp:
	        // We simplify the addition as much as we can
		// Case 1: two constants
	        if (roseAST->child(0)->getID() == AST::V_ConstantAST && roseAST->child(1)->getID() == AST::V_ConstantAST) {
		    ConstantAST::Ptr child0 = boost::static_pointer_cast<ConstantAST>(roseAST->child(0));
		    ConstantAST::Ptr child1 = boost::static_pointer_cast<ConstantAST>(roseAST->child(1));
		    uint64_t val = child0->val().val + child1->val().val;
		    size_t size;
		    if (child0->val().size > child1->val().size)
		        size = child0->val().size;
		    else
		        size = child1->val().size;
		    return ConstantAST::create(Constant(val,size));
   	        }
		// Case 2: anything adding zero stays the same
		if (roseAST->child(0)->getID() == AST::V_ConstantAST) {
		    ConstantAST::Ptr child = boost::static_pointer_cast<ConstantAST>(roseAST->child(0));
		    if (child->val().val == 0) return roseAST->child(1);
		}
		if (roseAST->child(1)->getID() == AST::V_ConstantAST) {
		    ConstantAST::Ptr child = boost::static_pointer_cast<ConstantAST>(roseAST->child(1));
		    if (child->val().val == 0) return roseAST->child(0);
		}
		// Case 3: if v + v * c = v * (c+1), where v is a variable and c is a constant
		if (roseAST->child(0)->getID() == AST::V_VariableAST && roseAST->child(1)->getID() == AST::V_RoseAST) {
		    RoseAST::Ptr rOp = boost::static_pointer_cast<RoseAST>(roseAST->child(1));
		    if (rOp->val().op == ROSEOperation::uMultOp || rOp->val().op == ROSEOperation::sMultOp) {
		        if (rOp->child(0)->getID() == AST::V_VariableAST && rOp->child(1)->getID() == AST::V_ConstantAST) {
			    VariableAST::Ptr varAST1 = boost::static_pointer_cast<VariableAST>(roseAST->child(0));
			    VariableAST::Ptr varAST2 = boost::static_pointer_cast<VariableAST>(rOp->child(0));
			    if (varAST1->val().reg == varAST2->val().reg) {
			        ConstantAST::Ptr oldC = boost::static_pointer_cast<ConstantAST>(rOp->child(1));
			        ConstantAST::Ptr newC = ConstantAST::create(Constant(oldC->val().val + 1, oldC->val().size));
				RoseAST::Ptr newRoot = RoseAST::create(ROSEOperation(rOp->val()), varAST1, newC);
				return newRoot;
			    }
			}
		    }
		} 
		break;
	    case ROSEOperation::sMultOp:
	    case ROSEOperation::uMultOp:
	        if (roseAST->child(0)->getID() == AST::V_ConstantAST) {
		    ConstantAST::Ptr child0 = boost::static_pointer_cast<ConstantAST>(roseAST->child(0));
		    if (child0->val().val == 1) return roseAST->child(1);
		}

	        if (roseAST->child(1)->getID() == AST::V_ConstantAST) {
		    ConstantAST::Ptr child1 = boost::static_pointer_cast<ConstantAST>(roseAST->child(1));
		    if (child1->val().val == 1) return roseAST->child(0);
		}
	        break;

	    case ROSEOperation::xorOp:
	        if (roseAST->child(0)->getID() == AST::V_VariableAST && roseAST->child(1)->getID() == AST::V_VariableAST) {
		    VariableAST::Ptr child0 = boost::static_pointer_cast<VariableAST>(roseAST->child(0)); 
		    VariableAST::Ptr child1 = boost::static_pointer_cast<VariableAST>(roseAST->child(1)); 
		    if (child0->val() == child1->val()) {
		        return ConstantAST::create(Constant(0 , 32));
		    }
  	        }
		break;
	    case ROSEOperation::derefOp:
	        // Any 8-bit value is bounded in [0,255].
		// Need to keep the length of the dereference if it is 8-bit.
		// However, dereference longer than 8-bit should be regarded the same.
	        if (roseAST->val().size == 8)
		    return ast;
		else
		    return RoseAST::create(ROSEOperation(ROSEOperation::derefOp), ast->child(0));
		break;
	    case ROSEOperation::shiftLOp:
	        if (roseAST->child(0)->getID() == AST::V_ConstantAST && roseAST->child(1)->getID() == AST::V_ConstantAST) {
		    ConstantAST::Ptr child0 = boost::static_pointer_cast<ConstantAST>(roseAST->child(0));
		    ConstantAST::Ptr child1 = boost::static_pointer_cast<ConstantAST>(roseAST->child(1));
		    return ConstantAST::create(Constant(child0->val().val << child1->val().val, 64));
		}
		break;
	    case ROSEOperation::andOp:
	        if (roseAST->child(0)->getID() == AST::V_ConstantAST && roseAST->child(1)->getID() == AST::V_ConstantAST) {
		    ConstantAST::Ptr child0 = boost::static_pointer_cast<ConstantAST>(roseAST->child(0));
		    ConstantAST::Ptr child1 = boost::static_pointer_cast<ConstantAST>(roseAST->child(1));
		    return ConstantAST::create(Constant(child0->val().val & child1->val().val, 64));
		}
		break;
	    case ROSEOperation::orOp:
	        if (roseAST->child(0)->getID() == AST::V_ConstantAST && roseAST->child(1)->getID() == AST::V_ConstantAST) {
		    ConstantAST::Ptr child0 = boost::static_pointer_cast<ConstantAST>(roseAST->child(0));
		    ConstantAST::Ptr child1 = boost::static_pointer_cast<ConstantAST>(roseAST->child(1));
		    return ConstantAST::create(Constant(child0->val().val | child1->val().val, 64));
		}
		break;

	    default:
	        break;

	}
    } else if (ast->getID() == AST::V_VariableAST) {
        VariableAST::Ptr varAST = boost::static_pointer_cast<VariableAST>(ast);
	if (varAST->val().reg.absloc().isPC()) {
	    MachRegister pc = varAST->val().reg.absloc().reg();	    
	    return ConstantAST::create(Constant(addr, getArchAddressWidth(pc.getArchitecture()) * 8));
	}
	// We do not care about the address of the a-loc
	// because we will keep tracking the changes of 
	// each a-loc. Also, this brings a benefit that
	// we can directly use ast->isStrictEqual() to 
	// compare two ast.
	return VariableAST::create(Variable(varAST->val().reg));
    } else if (ast->getID() == AST::V_ConstantAST) {
        ConstantAST::Ptr constAST = boost::static_pointer_cast<ConstantAST>(ast);
	size_t size = constAST->val().size;
	uint64_t val = constAST->val().val;	
	if (size == 32)
	    if (!(val & (1ULL << (size - 1))))
	        return ConstantAST::create(Constant(val, 64));
    }

    return ast;
}