Beispiel #1
0
// implements < , <= causes failures when used to sort Windows vectors
bool vectorSort(SliceNode::Ptr ptr1, SliceNode::Ptr ptr2) {

    AssignmentPtr assign1 = ptr1->assign();
    AssignmentPtr assign2 = ptr2->assign();

    if (!assign2) return false;
    else if (!assign1) return true;

    Address addr1 = assign1->addr();
    Address addr2 = assign2->addr();

    if (addr1 == addr2) {
        AbsRegion &out1 = assign1->out();
        AbsRegion &out2 = assign2->out();
        return out1 < out2;
    } else {
        return addr1 < addr2;
    }
}
Beispiel #2
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 #3
0
BoundFact* BoundFactsCalculator::Meet(Node::Ptr curNode) {

    SliceNode::Ptr node = boost::static_pointer_cast<SliceNode>(curNode);

    EdgeIterator gbegin, gend;
    curNode->ins(gbegin, gend);
    BoundFact* newFact = NULL;

    bool first = true;
    for (; gbegin != gend; ++gbegin) {
        TypedSliceEdge::Ptr edge = boost::static_pointer_cast<TypedSliceEdge>(*gbegin);
	SliceNode::Ptr srcNode = boost::static_pointer_cast<SliceNode>(edge->source());
	BoundFact *prevFact = GetBoundFactOut(srcNode);
	bool newCopy = false;
	if (prevFact == NULL) {
	    parsing_printf("\t\tIncoming node %lx has not been calculated yet, ignore it\n", srcNode->addr());
	    continue;
	} else {
	    // Otherwise, create a new copy.
	    // We do not want to overwrite the bound fact
	    // of the predecessor
	    prevFact = new BoundFact(*prevFact);
		newCopy = true;
	}
	parsing_printf("\t\tMeet incoming edge from %lx\n", srcNode->addr());
	parsing_printf("\t\tThe fact from %lx before applying transfer function\n", srcNode->addr());
	prevFact->Print();
	if (!srcNode->assign()) {
	    prevFact = new BoundFact(*prevFact);
	    newCopy = true;
	    parsing_printf("\t\tThe predecessor node is the virtual entry ndoe\n");
	    if (firstBlock) {
	        // If the indirect jump is in the entry block
	        // of the function, we assume that rax is in
	        // range [0,8] for analyzing the movaps table.
	        // NEED TO HAVE A SAFE WAY TO DO THIS!!
	        parsing_printf("\t\tApplying entry block rax assumption!\n");
	        AST::Ptr axAST;
	        if (func->entry()->obj()->cs()->getAddressWidth() == 8)
	            axAST = VariableAST::create(Variable(AbsRegion(Absloc(x86_64::rax))));
	        else
	            // DOES THIS REALLY SHOW UP IN 32-BIT CODE???
	            axAST = VariableAST::create(Variable(AbsRegion(Absloc(x86::eax))));
	        prevFact->GenFact(axAST, new BoundValue(StridedInterval(1,0,8)), false);
	    }
	} else if (srcNode->assign() && IsConditionalJump(srcNode->assign()->insn())) {
	    prevFact = new BoundFact(*prevFact);
	    newCopy = true;
	    // If the predecessor is a conditional jump,
	    // we can determine bound fact based on the predicate and the edge type
  	    parsing_printf("\t\tThe predecessor node is a conditional jump!\n");
	    if (!prevFact->ConditionalJumpBound(srcNode->assign()->insn(), edge->type())) {
	        fprintf(stderr, "From %lx to %lx\n", srcNode->addr(), node->addr());
		assert(0);
	    }
	}
	ThunkBound(prevFact, srcNode, node, newCopy);
	parsing_printf("\t\tFact from %lx after applying transfer function\n", srcNode->addr());
	prevFact->Print();
        if (first) {
	    // For the first incoming dataflow fact,
	    // we just copy it.
	    // We can do this because if an a-loc
	    // is missing in the fact map, we assume
	    // the a-loc is top.
	    first = false;
	    if (newCopy) newFact = prevFact; else newFact = new BoundFact(*prevFact);
	} else {
	    newFact->Meet(*prevFact);
	    if (newCopy) delete prevFact;
        }
    }
    return newFact;
}
Beispiel #4
0
bool BoundFactsCalculator::CalculateBoundedFacts() {
    /* We use a dataflow analysis to calculate the value bound
     * of each register and potentially some memory locations.
     * The key steps of the dataflow analysis are 
     * 1. Determine the analysis order:
     *    First calculate all strongly connected components (SCC)
     *    of the graph. The flow analysis inside a SCC is 
     *    iterative. The flow analysis between several SCCs
     *    is done topologically. 
     * 2. For each node, need to calculate the meet and 
     *    calculate the transfer function.
     * 1. The meet should be simply an intersection of all the bounded facts 
     * along all paths. 
     * 2. To calculate the transfer function, we first get the symbolic expression
     * of the instrution for the node. Then depending on the instruction operation
     * and the meet result, we know what are still bounded. For example, loading 
     * memory is always unbounded; doing and operation on a register with a constant
     * makes the register bounded. 
     */

    DetermineAnalysisOrder();
    queue<Node::Ptr> workingList;
    unordered_set<Node::Ptr, Node::NodePtrHasher> inQueue;
    unordered_map<Node::Ptr, int, Node::NodePtrHasher> inQueueLimit;

    for (int curOrder = 0; curOrder <= orderStamp; ++curOrder) {
        // We first determine which nodes are
	// in this SCC
        vector<Node::Ptr> curNodes;
	NodeIterator nbegin, nend;
	slice->allNodes(nbegin, nend);
	for (; nbegin != nend; ++nbegin) {
	    if (analysisOrder[*nbegin] == curOrder) {
	        curNodes.push_back(*nbegin);
		workingList.push(*nbegin);
		inQueue.insert(*nbegin);
	    }
	}

	if (!HasIncomingEdgesFromLowerLevel(curOrder, curNodes)) {
	    // If this SCC is an entry SCC,
	    // we choose a node inside the SCC
	    // and let it be top.
	    // This should only contain the virtual entry node
	    parsing_printf("This SCC does not incoming edges from outside\n");
	    boundFactsIn[curNodes[0]] = new BoundFact();
	    boundFactsOut[curNodes[0]] = new BoundFact();
	}
	parsing_printf("Starting analysis inside SCC %d\n", curOrder);
	// We now start iterative analysis inside the SCC
	while (!workingList.empty()) {
	    // We get the current node
	    Node::Ptr curNode = workingList.front();
	    workingList.pop();
	    inQueue.erase(curNode);

	    SliceNode::Ptr node = boost::static_pointer_cast<SliceNode>(curNode);
	    ++inQueueLimit[curNode];
	    if (inQueueLimit[curNode] > IN_QUEUE_LIMIT) continue;

	    BoundFact* oldFactIn = GetBoundFactIn(curNode);
	    parsing_printf("Calculate Meet for %lx", node->addr());
	    if (node->assign()) {
	        parsing_printf(", insn: %s\n", node->assign()->insn()->format().c_str());
	    }
	    else {
	        if (node->block() == NULL)
		    parsing_printf(", the VirtualExit node\n");
		else
		    parsing_printf(", the VirtualEntry node\n");

	    }
	    parsing_printf("\tOld fact for %lx:\n", node->addr());
	    if (oldFactIn == NULL) parsing_printf("\t\t do not exist\n"); else oldFactIn->Print();

	    // We find all predecessors of the current node
	    // and calculates the union of the analysis results
	    // from the predecessors
	    BoundFact* newFactIn = Meet(curNode);
	    parsing_printf("\tNew fact at %lx\n", node->addr());
	    if (newFactIn != NULL) newFactIn->Print(); else parsing_printf("\t\tNot calculated\n");

	    // If the current node has not been calcualted yet,
	    // or the new meet results are different from the
	    // old ones, we keep the new results
	    if (newFactIn != NULL && (oldFactIn == NULL || *oldFactIn != *newFactIn)) {
	        parsing_printf("\tFacts change!\n");
		if (oldFactIn != NULL) delete oldFactIn;
		boundFactsIn[curNode] = newFactIn;
		BoundFact* newFactOut = new BoundFact(*newFactIn);

		// The current node has a transfer function
		// that changes the analysis results
		CalcTransferFunction(curNode, newFactOut);

		if (boundFactsOut.find(curNode) != boundFactsOut.end() && boundFactsOut[curNode] != NULL)
		    delete boundFactsOut[curNode];
		boundFactsOut[curNode] = newFactOut;
		curNode->outs(nbegin, nend);
	        for (; nbegin != nend; ++nbegin)
		    // We only add node inside current SCC into the working list
		    if (inQueue.find(*nbegin) == inQueue.end() && analysisOrder[*nbegin] == curOrder) {
		        workingList.push(*nbegin);
			inQueue.insert(*nbegin);
		    }
	    } else {
	        if (newFactIn != NULL) delete newFactIn;
		parsing_printf("\tFacts do not change!\n");
	    }

        }
    }

    return true;
}
Beispiel #5
0
SymEval::Retval_t SymEval::process(SliceNode::Ptr ptr,
                                   Result_t &dbase,
                                   std::set<Edge::Ptr> &skipEdges) {
    bool failedTranslation;
    bool skippedEdge = false;
    bool skippedInput = false;
    bool success = false;

    std::map<const AbsRegion*, std::set<Assignment::Ptr> > inputMap;

    expand_cerr << "Calling process on " << ptr->format() << endl;

    // Don't try an expansion of a widen node...
    if (!ptr->assign()) return WIDEN_NODE;

    EdgeIterator begin, end;
    ptr->ins(begin, end);

    for (; begin != end; ++begin) {
        SliceEdge::Ptr edge = boost::static_pointer_cast<SliceEdge>(*begin);
        SliceNode::Ptr source = boost::static_pointer_cast<SliceNode>(edge->source());

        // Skip this one to break a cycle.
        if (skipEdges.find(edge) != skipEdges.end()) {
            expand_cerr << "In process, skipping edge from "
                        << source->format() << endl;
            skippedEdge = true;
            continue;
        }

        Assignment::Ptr assign = source->assign();
        if (!assign) continue; // widen node

        expand_cerr << "Assigning input " << edge->data().format()
                    << " from assignment " << assign->format() << endl;
        inputMap[&edge->data()].insert(assign);
    }

    expand_cerr << "\t Input map has size " << inputMap.size() << endl;

    // All of the expanded inputs are in the parameter dbase
    // If not (like this one), add it

    AST::Ptr ast;
    boost::tie(ast, failedTranslation) = SymEval::expand(ptr->assign());
    // expand_cerr << "\t ... resulting in " << dbase.format() << endl;

    // We have an AST. Now substitute in all of its predecessors.
    for (std::map<const AbsRegion*, std::set<Assignment::Ptr> >::iterator iter = inputMap.begin();
            iter != inputMap.end(); ++iter) {
        // If we have multiple secondary definitions, we:
        //   if all definitions are equal, use the first
        //   otherwise, use nothing
        AST::Ptr definition;

        for (std::set<Assignment::Ptr>::iterator iter2 = iter->second.begin();
                iter2 != iter->second.end(); ++iter2) {
            AST::Ptr newDef = dbase[*iter2];
            if (!definition) {
                definition = newDef;
                continue;
            } else if (definition->equals(newDef)) {
                continue;
            } else {
                // Not equal
                definition = AST::Ptr();
                skippedInput = true;
                break;
            }
        }

        // The region used by the current assignment...
        const AbsRegion &reg = *iter->first;

        // Create an AST around this one
        VariableAST::Ptr use = VariableAST::create(Variable(reg, ptr->addr()));

        if (!definition) {
            // Can happen if we're expanding out of order, and is generally harmless.
            continue;
        }

        expand_cerr << "Before substitution: " << (ast ? ast->format() : "<NULL AST>") << endl;

        if (!ast) {
            expand_cerr << "Skipping substitution because of null AST" << endl;
        } else {
            ast = AST::substitute(ast, use, definition);
            success = true;
        }
        expand_cerr << "\t result is " << (ast ? ast->format() : "<NULL AST>") << endl;
    }
    expand_cerr << "Result of substitution: " << ptr->assign()->format() << " == "
                << (ast ? ast->format() : "<NULL AST>") << endl;

    // And attempt simplification again
    ast = simplifyStack(ast, ptr->addr(), ptr->func(), ptr->block());
    expand_cerr << "Result of post-substitution simplification: " << ptr->assign()->format() << " == "
                << (ast ? ast->format() : "<NULL AST>") << endl;

    dbase[ptr->assign()] = ast;
    if (failedTranslation) return FAILED_TRANSLATION;
    else if (skippedEdge || skippedInput) return SKIPPED_INPUT;
    else if (success) return SUCCESS;
    else return FAILED;
}
Beispiel #6
0
// Do the previous, but use a Graph as a guide for
// performing forward substitution on the AST results
SymEval::Retval_t SymEval::expand(Dyninst::Graph::Ptr slice, DataflowAPI::Result_t &res) {
    bool failedTranslation = false;
    bool skippedInput = false;

    //cout << "Calling expand" << endl;
    // Other than the substitution this is pretty similar to the first example.
    NodeIterator gbegin, gend;
    slice->allNodes(gbegin, gend);

    // First, we'll sort the nodes in some deterministic order so that the loop removal
    // is deterministic
    std::vector<SliceNode::Ptr> sortVector;
    for ( ; gbegin != gend; ++gbegin) {
        Node::Ptr ptr = *gbegin;
        expand_cerr << "pushing " << (*gbegin)->format() << " to sortVector" << endl;
        SliceNode::Ptr cur = boost::static_pointer_cast<SliceNode>(ptr);
        sortVector.push_back(cur);
    }
    std::stable_sort(sortVector.begin(), sortVector.end(), vectorSort);

    // Optimal ordering of search
    ExpandOrder worklist;

    std::queue<Node::Ptr> dfs_worklist;
    std::vector<SliceNode::Ptr>::iterator vit = sortVector.begin();
    for ( ; vit != sortVector.end(); ++vit) {
        SliceNode::Ptr ptr = *vit;
        Node::Ptr cur = boost::static_pointer_cast<Node>(ptr);
        dfs_worklist.push(cur);
    }

    /* First, we'll do DFS to check for circularities in the graph;
     * if so, mark them so we don't do infinite substitution */
    std::map<Node::Ptr, int> state;
    while (!dfs_worklist.empty()) {
        Node::Ptr ptr = dfs_worklist.front();
        dfs_worklist.pop();
        dfs(ptr, state, worklist.skipEdges());
    }

    slice->allNodes(gbegin, gend);
    for (; gbegin != gend; ++gbegin) {
        expand_cerr << "adding " << (*gbegin)->format() << " to worklist" << endl;
        Node::Ptr ptr = *gbegin;
        SliceNode::Ptr sptr =
            boost::static_pointer_cast<SliceNode>(ptr);
        worklist.insert(sptr,false);
    }

    /* have a list
     * for each node, process
     * if processessing succeeded, remove the element
     * if the size of the list has changed, continue */

    while (1) {
        SliceNode::Ptr aNode;
        int order;

        boost::tie(aNode,order) = worklist.pop_next();
        if (order == -1) // empty
            break;

        if (!aNode->assign()) {
            worklist.mark_done(aNode);
            continue; // Could be a widen point
        }

        expand_cerr << "Visiting node " << aNode->assign()->format()
                    << " order " << order << endl;

        if (order != 0) {
            cerr << "ERROR: order is non zero: " << order << endl;
        }
        assert(order == 0); // there are no loops

        AST::Ptr prev = res[aNode->assign()];
        Retval_t result = process(aNode, res, worklist.skipEdges());
        AST::Ptr post = res[aNode->assign()];
        switch (result) {
        case FAILED:
            return FAILED;
            break;
        case WIDEN_NODE:
            // Okay...
            break;
        case FAILED_TRANSLATION:
            failedTranslation = true;
            break;
        case SKIPPED_INPUT:
            skippedInput = true;
            break;
        case SUCCESS:
            break;
        }

        // We've visited this node, freeing its children
        // to be visited in turn
        worklist.mark_done(aNode);

        if (post && !(post->equals(prev))) {
            expand_cerr << "Adding successors to list, as new expansion " << endl
                        << "\t" << post->format() << endl
                        << " != " << endl
                        << "\t" << (prev ? prev->format() : "<NULL>") << endl;
            EdgeIterator oB, oE;
            aNode->outs(oB, oE);
            for (; oB != oE; ++oB) {
                if(worklist.skipEdges().find(*oB) == worklist.skipEdges().end()) {
                    SliceNode::Ptr out =
                        boost::static_pointer_cast<SliceNode>(
                            (*oB)->target());
                    worklist.insert(out);
                }
            }
        }
    }
    if (failedTranslation) return FAILED_TRANSLATION;
    else if (skippedInput) return SKIPPED_INPUT;
    else return SUCCESS;
}