729 lines
25 KiB
Java
729 lines
25 KiB
Java
/*
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* Copyright (c) 2009 VeriSign, Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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package com.versign.tat.dnssec;
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import java.security.MessageDigest;
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import java.security.NoSuchAlgorithmException;
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import java.util.Iterator;
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import org.xbill.DNS.*;
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/**
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* This is a collection of routines encompassing the logic of validating
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* different message types.
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*/
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public class ValUtils {
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// These are response subtypes. They are necessary for determining the
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// validation strategy. They have no bearing on the iterative resolution
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// algorithm, so they are confined here.
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/** Not subtyped yet. */
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public static final int UNTYPED = 0;
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/** Not a recognized subtype. */
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public static final int UNKNOWN = 1;
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/** A postive, direct, response. */
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public static final int POSITIVE = 2;
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/** A postive response, with a CNAME/DNAME chain. */
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public static final int CNAME = 3;
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/** A NOERROR/NODATA response. */
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public static final int NODATA = 4;
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/** A NXDOMAIN response. */
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public static final int NAMEERROR = 5;
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/** A response to a qtype=ANY query. */
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public static final int ANY = 6;
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/** A local copy of the verifier object. */
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private DnsSecVerifier mVerifier;
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public ValUtils(DnsSecVerifier verifier) {
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mVerifier = verifier;
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}
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/**
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* Given a response, classify ANSWER responses into a subtype.
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*
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* @param m
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* The response to classify.
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*
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* @return A subtype ranging from UNKNOWN to NAMEERROR.
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*/
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public static int classifyResponse(SMessage m) {
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// Normal Name Error's are easy to detect -- but don't mistake a CNAME
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// chain ending in NXDOMAIN.
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if (m.getRcode() == Rcode.NXDOMAIN && m.getCount(Section.ANSWER) == 0) {
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return NAMEERROR;
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}
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// Next is NODATA
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// st_log.debug("classifyResponse: ancount = " +
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// m.getCount(Section.ANSWER));
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if (m.getCount(Section.ANSWER) == 0) {
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return NODATA;
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}
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// We distinguish between CNAME response and other positive/negative
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// responses because CNAME answers require extra processing.
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int qtype = m.getQuestion().getType();
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// We distinguish between ANY and CNAME or POSITIVE because ANY
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// responses
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// are validated differently.
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if (qtype == Type.ANY) {
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return ANY;
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}
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SRRset[] rrsets = m.getSectionRRsets(Section.ANSWER);
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// Note that DNAMEs will be ignored here, unless qtype=DNAME. Unless
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// qtype=CNAME, this will yield a CNAME response.
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for (int i = 0; i < rrsets.length; i++) {
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if (rrsets[i].getType() == qtype) return POSITIVE;
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if (rrsets[i].getType() == Type.CNAME) return CNAME;
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}
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// st_log.warn("Failed to classify response message:\n" + m);
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return UNKNOWN;
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}
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/**
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* Given a response, determine the name of the "signer". This is primarily
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* to determine if the response is, in fact, signed at all, and, if so, what
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* is the name of the most pertinent keyset.
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*
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* @param m
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* The response to analyze.
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* @param request
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* The request that generated the response.
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* @return a signer name, if the response is signed (even partially), or
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* null if the response isn't signed.
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*/
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public Name findSigner(SMessage m) {
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int subtype = classifyResponse(m);
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Name qname = m.getQName();
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SRRset[] rrsets;
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switch (subtype) {
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case POSITIVE:
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case CNAME:
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case ANY:
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// Check to see if the ANSWER section RRset
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rrsets = m.getSectionRRsets(Section.ANSWER);
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for (int i = 0; i < rrsets.length; i++) {
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if (rrsets[i].getName().equals(qname)) {
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return rrsets[i].getSignerName();
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}
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}
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return null;
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case NAMEERROR:
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case NODATA:
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// Check to see if the AUTH section NSEC record(s) have rrsigs
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rrsets = m.getSectionRRsets(Section.AUTHORITY);
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for (int i = 0; i < rrsets.length; i++) {
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if (rrsets[i].getType() == Type.NSEC
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|| rrsets[i].getType() == Type.NSEC3) {
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return rrsets[i].getSignerName();
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}
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}
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return null;
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default:
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// log.debug("findSigner: could not find signer name "
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// + "for unknown type response.");
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return null;
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}
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}
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public boolean dssetIsUsable(SRRset ds_rrset) {
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for (Iterator i = ds_rrset.rrs(); i.hasNext();) {
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DSRecord ds = (DSRecord) i.next();
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if (supportsDigestID(ds.getDigestID())
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&& mVerifier.supportsAlgorithm(ds.getAlgorithm())) {
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return true;
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}
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}
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return false;
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}
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/**
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* Given a DS rrset and a DNSKEY rrset, match the DS to a DNSKEY and verify
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* the DNSKEY rrset with that key.
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*
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* @param dnskey_rrset
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* The DNSKEY rrset to match against. The security status of this
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* rrset will be updated on a successful verification.
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* @param ds_rrset
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* The DS rrset to match with. This rrset must already be
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* trusted.
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*
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* @return a KeyEntry. This will either contain the now trusted
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* dnskey_rrset, a "null" key entry indicating that this DS
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* rrset/DNSKEY pair indicate an secure end to the island of trust
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* (i.e., unknown algorithms), or a "bad" KeyEntry if the dnskey
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* rrset fails to verify. Note that the "null" response should
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* generally only occur in a private algorithm scenario: normally
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* this sort of thing is checked before fetching the matching DNSKEY
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* rrset.
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*/
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// public KeyEntry verifyNewDNSKEYs(SRRset dnskey_rrset, SRRset ds_rrset)
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// {
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// if (!dnskey_rrset.getName().equals(ds_rrset.getName()))
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// {
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// // log.debug("DNSKEY RRset did not match DS RRset by name!");
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// return KeyEntry
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// .newBadKeyEntry(ds_rrset.getName(), ds_rrset.getDClass());
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// }
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//
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// // as long as this is false, we can consider this DS rrset to be
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// // equivalent to no DS rrset.
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// boolean hasUsefulDS = false;
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//
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// for (Iterator i = ds_rrset.rrs(); i.hasNext();)
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// {
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// DSRecord ds = (DSRecord) i.next();
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//
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// // Check to see if we can understand this DS.
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// if (!supportsDigestID(ds.getDigestID())
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// || !mVerifier.supportsAlgorithm(ds.getAlgorithm()))
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// {
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// continue;
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// }
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//
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// // Once we see a single DS with a known digestID and algorithm, we
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// // cannot return INSECURE (with a "null" KeyEntry).
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// hasUsefulDS = true;
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//
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// DNSKEY : for (Iterator j = dnskey_rrset.rrs(); j.hasNext();)
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// {
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// DNSKEYRecord dnskey = (DNSKEYRecord) j.next();
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//
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// // Skip DNSKEYs that don't match the basic criteria.
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// if (ds.getFootprint() != dnskey.getFootprint()
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// || ds.getAlgorithm() != dnskey.getAlgorithm())
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// {
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// continue;
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// }
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//
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// // Convert the candidate DNSKEY into a hash using the same DS hash
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// // algorithm.
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// byte[] key_hash = calculateDSHash(dnskey, ds.getDigestID());
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// byte[] ds_hash = ds.getDigest();
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//
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// // see if there is a length mismatch (unlikely)
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// if (key_hash.length != ds_hash.length)
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// {
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// continue DNSKEY;
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// }
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//
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// for (int k = 0; k < key_hash.length; k++)
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// {
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// if (key_hash[k] != ds_hash[k]) continue DNSKEY;
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// }
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//
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// // Otherwise, we have a match! Make sure that the DNSKEY verifies
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// // *with this key*.
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// byte res = mVerifier.verify(dnskey_rrset, dnskey);
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// if (res == SecurityStatus.SECURE)
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// {
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// // log.trace("DS matched DNSKEY.");
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// dnskey_rrset.setSecurityStatus(SecurityStatus.SECURE);
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// return KeyEntry.newKeyEntry(dnskey_rrset);
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// }
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// // If it didn't validate with the DNSKEY, try the next one!
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// }
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// }
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//
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// // None of the DS's worked out.
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//
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// // If no DSs were understandable, then this is OK.
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// if (!hasUsefulDS)
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// {
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// //
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// log.debug("No usuable DS records were found -- treating as insecure.");
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// return KeyEntry.newNullKeyEntry(ds_rrset.getName(), ds_rrset
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// .getDClass(), ds_rrset.getTTL());
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// }
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// // If any were understandable, then it is bad.
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// // log.debug("Failed to match any usable DS to a DNSKEY.");
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// return KeyEntry.newBadKeyEntry(ds_rrset.getName(), ds_rrset.getDClass());
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// }
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/**
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* Given a DNSKEY record, generate the DS record from it.
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*
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* @param keyrec
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* the DNSKEY record in question.
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* @param ds_alg
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* The DS digest algorithm in use.
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* @return the corresponding {@link org.xbill.DNS.DSRecord}
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*/
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public static byte[] calculateDSHash(DNSKEYRecord keyrec, int ds_alg) {
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DNSOutput os = new DNSOutput();
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os.writeByteArray(keyrec.getName().toWireCanonical());
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os.writeByteArray(keyrec.rdataToWireCanonical());
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try {
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MessageDigest md = null;
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switch (ds_alg) {
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case DSRecord.SHA1_DIGEST_ID:
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md = MessageDigest.getInstance("SHA");
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return md.digest(os.toByteArray());
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case DSRecord.SHA256_DIGEST_ID:
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md = MessageDigest.getInstance("SHA256");
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return md.digest(os.toByteArray());
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default:
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// st_log.warn("Unknown DS algorithm: " + ds_alg);
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return null;
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}
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} catch (NoSuchAlgorithmException e) {
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// st_log.error("Error using DS algorithm: " + ds_alg, e);
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return null;
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}
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}
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public static boolean supportsDigestID(int digest_id) {
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if (digest_id == DSRecord.SHA1_DIGEST_ID) return true;
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if (digest_id == DSRecord.SHA256_DIGEST_ID) return true;
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return false;
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}
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/**
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* Check to see if a type is a special DNSSEC type.
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*
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* @param type
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* The type.
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*
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* @return true if the type is one of the special DNSSEC types.
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*/
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public static boolean isDNSSECType(int type) {
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switch (type) {
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case Type.DNSKEY:
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case Type.NSEC:
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case Type.DS:
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case Type.RRSIG:
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case Type.NSEC3:
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return true;
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default:
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return false;
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}
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}
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/**
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* Set the security status of a particular RRset. This will only upgrade the
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* security status.
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*
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* @param rrset
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* The SRRset to update.
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* @param security
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* The security status.
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*/
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public static void setRRsetSecurity(SRRset rrset, byte security) {
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if (rrset == null) return;
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int cur_sec = rrset.getSecurityStatus();
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if (cur_sec == SecurityStatus.UNCHECKED || security > cur_sec) {
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rrset.setSecurityStatus(security);
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}
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}
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/**
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* Set the security status of a message and all of its RRsets. This will
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* only upgrade the status of the message (i.e., set to more secure, not
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* less) and all of the RRsets.
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*
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* @param m
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* @param security
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* KeyEntry ke;
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*
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* SMessage m = response.getSMessage(); SRRset ans_rrset =
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* m.findAnswerRRset(qname, qtype, qclass);
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*
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* ke = verifySRRset(ans_rrset, key_rrset); if
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* (ans_rrset.getSecurityStatus() != SecurityStatus.SECURE) {
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* return; } key_rrset = ke.getRRset();
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*/
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public static void setMessageSecurity(SMessage m, byte security) {
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if (m == null) return;
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int cur_sec = m.getStatus();
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if (cur_sec == SecurityStatus.UNCHECKED || security > cur_sec) {
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m.setStatus(security);
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}
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for (int section = Section.ANSWER; section <= Section.ADDITIONAL; section++) {
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SRRset[] rrsets = m.getSectionRRsets(section);
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for (int i = 0; i < rrsets.length; i++) {
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setRRsetSecurity(rrsets[i], security);
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}
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}
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}
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/**
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* Given an SRRset that is signed by a DNSKEY found in the key_rrset, verify
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* it. This will return the status (either BOGUS or SECURE) and set that
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* status in rrset.
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*
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* @param rrset
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* The SRRset to verify.
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* @param key_rrset
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* The set of keys to verify against.
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* @return The status (BOGUS or SECURE).
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*/
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public byte verifySRRset(SRRset rrset, SRRset key_rrset) {
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String rrset_name = rrset.getName() + "/"
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+ Type.string(rrset.getType()) + "/"
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+ DClass.string(rrset.getDClass());
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if (rrset.getSecurityStatus() == SecurityStatus.SECURE) {
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// log.trace("verifySRRset: rrset <" + rrset_name
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// + "> previously found to be SECURE");
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return SecurityStatus.SECURE;
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}
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byte status = mVerifier.verify(rrset, key_rrset);
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if (status != SecurityStatus.SECURE) {
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// log.debug("verifySRRset: rrset <" + rrset_name +
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// "> found to be BAD");
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status = SecurityStatus.BOGUS;
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}
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// else
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// {
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// log.trace("verifySRRset: rrset <" + rrset_name +
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// "> found to be SECURE");
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// }
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rrset.setSecurityStatus(status);
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return status;
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}
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/**
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* Determine if a given type map has a given typ.
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*
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* @param types
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* The type map from the NSEC record.
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* @param type
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* The type to look for.
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* @return true if the type is present in the type map, false otherwise.
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*/
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public static boolean typeMapHasType(int[] types, int type) {
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for (int i = 0; i < types.length; i++) {
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if (types[i] == type) return true;
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}
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return false;
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}
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public static RRSIGRecord rrsetFirstSig(RRset rrset) {
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for (Iterator i = rrset.sigs(); i.hasNext();) {
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return (RRSIGRecord) i.next();
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}
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return null;
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}
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/**
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* Finds the longest common name between two domain names.
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*
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* @param domain1
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* @param domain2
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* @return
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*/
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public static Name longestCommonName(Name domain1, Name domain2) {
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if (domain1 == null || domain2 == null) return null;
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// for now, do this in a a fairly brute force way
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// FIXME: convert this to direct operations on the byte[]
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int d1_labels = domain1.labels();
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int d2_labels = domain2.labels();
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int l = (d1_labels < d2_labels) ? d1_labels : d2_labels;
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for (int i = l; i > 0; i--) {
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Name n1 = new Name(domain1, d1_labels - i);
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Name n2 = new Name(domain2, d2_labels - i);
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if (n1.equals(n2)) {
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return n1;
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}
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}
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return Name.root;
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}
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public static boolean strictSubdomain(Name child, Name parent) {
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int clabels = child.labels();
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int plabels = parent.labels();
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if (plabels >= clabels) return false;
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Name n = new Name(child, clabels - plabels);
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return parent.equals(n);
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}
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/**
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* Determine by looking at a signed RRset whether or not the rrset name was
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* the result of a wildcard expansion.
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*
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* @param rrset
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* The rrset to examine.
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* @return true if the rrset is a wildcard expansion. This will return false
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* for all unsigned rrsets.
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*/
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public static boolean rrsetIsWildcardExpansion(RRset rrset) {
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if (rrset == null) return false;
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RRSIGRecord rrsig = rrsetFirstSig(rrset);
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if (rrset.getName().labels() - 1 > rrsig.getLabels()) {
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return true;
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}
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return false;
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}
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/**
|
|
* Determine by looking at a signed RRset whether or not the RRset name was
|
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* the result of a wildcard expansion. If so, return the name of the
|
|
* generating wildcard.
|
|
*
|
|
* @param rrset
|
|
* The rrset to chedck.
|
|
* @return the wildcard name, if the rrset was synthesized from a wildcard.
|
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* null if not.
|
|
*/
|
|
public static Name rrsetWildcard(RRset rrset) {
|
|
if (rrset == null) return null;
|
|
RRSIGRecord rrsig = rrsetFirstSig(rrset);
|
|
|
|
// if the RRSIG label count is shorter than the number of actual labels,
|
|
// then this rrset was synthesized from a wildcard.
|
|
// Note that the RRSIG label count doesn't count the root label.
|
|
int label_diff = (rrset.getName().labels() - 1) - rrsig.getLabels();
|
|
if (label_diff > 0) {
|
|
return rrset.getName().wild(label_diff);
|
|
}
|
|
return null;
|
|
}
|
|
|
|
public static Name closestEncloser(Name domain, NSECRecord nsec) {
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Name n1 = longestCommonName(domain, nsec.getName());
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|
Name n2 = longestCommonName(domain, nsec.getNext());
|
|
|
|
return (n1.labels() > n2.labels()) ? n1 : n2;
|
|
}
|
|
|
|
public static Name nsecWildcard(Name domain, NSECRecord nsec) {
|
|
try {
|
|
return new Name("*", closestEncloser(domain, nsec));
|
|
} catch (TextParseException e) {
|
|
// this should never happen.
|
|
return null;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Determine if the given NSEC proves a NameError (NXDOMAIN) for a given
|
|
* qname.
|
|
*
|
|
* @param nsec
|
|
* The NSEC to check.
|
|
* @param qname
|
|
* The qname to check against.
|
|
* @param signerName
|
|
* The signer name of the NSEC record, which is used as the zone
|
|
* name, for a more precise (but perhaps more brittle) check for
|
|
* the last NSEC in a zone.
|
|
* @return true if the NSEC proves the condition.
|
|
*/
|
|
public static boolean nsecProvesNameError(NSECRecord nsec, Name qname,
|
|
Name signerName) {
|
|
Name owner = nsec.getName();
|
|
Name next = nsec.getNext();
|
|
|
|
// If NSEC owner == qname, then this NSEC proves that qname exists.
|
|
if (qname.equals(owner)) {
|
|
return false;
|
|
}
|
|
|
|
// If NSEC is a parent of qname, we need to check the type map
|
|
// If the parent name has a DNAME or is a delegation point, then this
|
|
// NSEC
|
|
// is being misused.
|
|
if (qname.subdomain(owner)
|
|
&& (typeMapHasType(nsec.getTypes(), Type.DNAME) || (typeMapHasType(
|
|
nsec.getTypes(),
|
|
Type.NS) && !typeMapHasType(
|
|
nsec.getTypes(),
|
|
Type.SOA)))) {
|
|
return false;
|
|
}
|
|
|
|
if (qname.compareTo(owner) > 0 && (qname.compareTo(next) < 0)
|
|
|| signerName.equals(next)) {
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* Determine if a NSEC record proves the non-existence of a wildcard that
|
|
* could have produced qname.
|
|
*
|
|
* @param nsec
|
|
* The nsec to check.
|
|
* @param qname
|
|
* The qname to check against.
|
|
* @param signerName
|
|
* The signer name for the NSEC rrset, used as the zone name.
|
|
* @return true if the NSEC proves the condition.
|
|
*/
|
|
public static boolean nsecProvesNoWC(NSECRecord nsec, Name qname,
|
|
Name signerName) {
|
|
Name owner = nsec.getName();
|
|
Name next = nsec.getNext();
|
|
|
|
int qname_labels = qname.labels();
|
|
int signer_labels = signerName.labels();
|
|
|
|
for (int i = qname_labels - signer_labels; i > 0; i--) {
|
|
Name wc_name = qname.wild(i);
|
|
if (wc_name.compareTo(owner) > 0
|
|
&& (wc_name.compareTo(next) < 0 || signerName.equals(next))) {
|
|
return true;
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* Determine if a NSEC proves the NOERROR/NODATA conditions. This will also
|
|
* handle the empty non-terminal (ENT) case and partially handle the
|
|
* wildcard case. If the ownername of 'nsec' is a wildcard, the validator
|
|
* must still be provided proof that qname did not directly exist and that
|
|
* the wildcard is, in fact, *.closest_encloser.
|
|
*
|
|
* @param nsec
|
|
* The NSEC to check
|
|
* @param qname
|
|
* The query name to check against.
|
|
* @param qtype
|
|
* The query type to check against.
|
|
* @return true if the NSEC proves the condition.
|
|
*/
|
|
public static boolean nsecProvesNodata(NSECRecord nsec, Name qname,
|
|
int qtype) {
|
|
if (!nsec.getName().equals(qname)) {
|
|
// wildcard checking.
|
|
|
|
// If this is a wildcard NSEC, make sure that a) it was possible to
|
|
// have
|
|
// generated qname from the wildcard and b) the type map does not
|
|
// contain qtype. Note that this does NOT prove that this wildcard
|
|
// was
|
|
// the applicable wildcard.
|
|
if (nsec.getName().isWild()) {
|
|
// the is the purported closest encloser.
|
|
Name ce = new Name(nsec.getName(), 1);
|
|
|
|
// The qname must be a strict subdomain of the closest encloser,
|
|
// and
|
|
// the qtype must be absent from the type map.
|
|
if (!strictSubdomain(qname, ce)
|
|
|| typeMapHasType(nsec.getTypes(), qtype)) {
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
// empty-non-terminal checking.
|
|
|
|
// If the nsec is proving that qname is an ENT, the nsec owner will
|
|
// be
|
|
// less than qname, and the next name will be a child domain of the
|
|
// qname.
|
|
if (strictSubdomain(nsec.getNext(), qname)
|
|
&& qname.compareTo(nsec.getName()) > 0) {
|
|
return true;
|
|
}
|
|
// Otherwise, this NSEC does not prove ENT, so it does not prove
|
|
// NODATA.
|
|
return false;
|
|
}
|
|
|
|
// If the qtype exists, then we should have gotten it.
|
|
if (typeMapHasType(nsec.getTypes(), qtype)) {
|
|
return false;
|
|
}
|
|
|
|
// if the name is a CNAME node, then we should have gotten the CNAME
|
|
if (typeMapHasType(nsec.getTypes(), Type.CNAME)) {
|
|
return false;
|
|
}
|
|
|
|
// If an NS set exists at this name, and NOT a SOA (so this is a zone
|
|
// cut,
|
|
// not a zone apex), then we should have gotten a referral (or we just
|
|
// got
|
|
// the wrong NSEC).
|
|
if (typeMapHasType(nsec.getTypes(), Type.NS)
|
|
&& !typeMapHasType(nsec.getTypes(), Type.SOA)) {
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
public static int nsecProvesNoDS(NSECRecord nsec, Name qname) {
|
|
// Could check to make sure the qname is a subdomain of nsec
|
|
int[] types = nsec.getTypes();
|
|
if (typeMapHasType(types, Type.SOA) || typeMapHasType(types, Type.DS)) {
|
|
// SOA present means that this is the NSEC from the child, not the
|
|
// parent (so it is the wrong one)
|
|
// DS present means that there should have been a positive response
|
|
// to
|
|
// the DS query, so there is something wrong.
|
|
return SecurityStatus.BOGUS;
|
|
}
|
|
|
|
if (!typeMapHasType(types, Type.NS)) {
|
|
// If there is no NS at this point at all, then this doesn't prove
|
|
// anything one way or the other.
|
|
return SecurityStatus.INSECURE;
|
|
}
|
|
// Otherwise, this proves no DS.
|
|
return SecurityStatus.SECURE;
|
|
}
|
|
|
|
}
|