720 lines
22 KiB
Java
720 lines
22 KiB
Java
/*
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* $Id$
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*
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* Copyright (c) 2005 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 se.rfc.unbound.validator;
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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.apache.log4j.Logger;
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import org.xbill.DNS.*;
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import se.rfc.unbound.*;
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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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* @author davidb
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* @version $Revision$
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*/
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public class ValUtils
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{
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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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private Logger log = Logger.getLogger(this.getClass());
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private static Logger st_log = Logger.getLogger(ValUtils.class);
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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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{
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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 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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{
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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
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&& m.getCount(Section.ANSWER) == 0)
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{
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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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{
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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 responses
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// are validated differently.
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if (qtype == Type.ANY)
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{
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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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{
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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 The response to analyze.
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* @param request 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, Request request)
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{
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int subtype = classifyResponse(m);
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Name qname = request.getQName();
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SRRset[] rrsets;
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switch (subtype)
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{
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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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{
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if (rrsets[i].getName().equals(qname))
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{
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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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{
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if (rrsets[i].getType() == Type.NSEC
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|| rrsets[i].getType() == Type.NSEC3)
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{
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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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{
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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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if (supportsDigestID(ds.getDigestID())
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&& mVerifier.supportsAlgorithm(ds.getAlgorithm()))
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{
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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 The DNSKEY rrset to match against. The security
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* status of this rrset will be updated on a successful
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* verification.
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* @param ds_rrset 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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// 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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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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// 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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// 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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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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// 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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// 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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// 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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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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// 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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// None of the DS's worked out.
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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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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 the DNSKEY record in question.
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* @param ds_alg 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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{
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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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{
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MessageDigest md = null;
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switch (ds_alg)
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{
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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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SHA256 sha = new SHA256();
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sha.setData(os.toByteArray());
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return sha.getDigest();
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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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}
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catch (NoSuchAlgorithmException e)
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{
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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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{
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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 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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{
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switch (type)
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{
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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 The SRRset to update.
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* @param security The security status.
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*/
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public static void setRRsetSecurity(SRRset rrset, int security)
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{
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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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{
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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 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) { return; }
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* key_rrset = ke.getRRset();
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*/
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public static void setMessageSecurity(SMessage m, int security)
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{
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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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{
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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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{
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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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{
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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 The SRRset to verify.
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* @param key_rrset 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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{
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String rrset_name = rrset.getName() + "/" + 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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{
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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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{
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log.debug("verifySRRset: rrset <" + rrset_name + "> 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 + "> 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 The type map from the NSEC record.
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* @param type 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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{
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for (int i = 0; i < types.length; i++)
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{
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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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/**
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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 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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{
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if (rrset == null) return false;
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RRSIGRecord rrsig = (RRSIGRecord) rrset.firstSig();
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if (rrset.getName().labels() - 1 > rrsig.getLabels())
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{
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return true;
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}
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return false;
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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. If so, return the name of the
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* generating wildcard.
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*
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* @param rrset The rrset to chedck.
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* @return the wildcard name, if the rrset was synthesized from a wildcard.
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* null if not.
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*/
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public static Name rrsetWildcard(RRset rrset)
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{
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if (rrset == null) return null;
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RRSIGRecord rrsig = (RRSIGRecord) rrset.firstSig();
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// if the RRSIG label count is shorter than the number of actual labels,
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// then this rrset was synthesized from a wildcard.
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// Note that the RRSIG label count doesn't count the root label.
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int label_diff = (rrset.getName().labels() - 1) - rrsig.getLabels();
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if (label_diff > 0)
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{
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return rrset.getName().wild(label_diff);
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}
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return null;
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}
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public static Name closestEncloser(Name domain, NSECRecord nsec)
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{
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Name n1 = domain.longestCommonName(nsec.getName());
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|
Name n2 = domain.longestCommonName(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 (!qname.strictSubdomain(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 (nsec.getNext().strictSubdomain(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;
|
|
}
|
|
|
|
}
|