pdns/dnssecsigner.cc

   1 /*
   2  * This file is part of PowerDNS or dnsdist.
   3  * Copyright -- PowerDNS.COM B.V. and its contributors
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of version 2 of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * In addition, for the avoidance of any doubt, permission is granted to
  10  * link this program with OpenSSL and to (re)distribute the binaries
  11  * produced as the result of such linking.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22 #ifdef HAVE_CONFIG_H
  23 #include "config.h"
  24 #endif
  25 #include "dnssecinfra.hh"
  26 #include "namespaces.hh"
  27
  28 #include "md5.hh"
  29 #include "dnsseckeeper.hh"
  30 #include "dns_random.hh"
  31 #include "lock.hh"
  32 #include "arguments.hh"
  33 #include "statbag.hh"
  34 extern StatBag S;
  35
  36 /* this is where the RRSIGs begin, keys are retrieved,
  37    but the actual signing happens in fillOutRRSIG */
  38 int getRRSIGsForRRSET(DNSSECKeeper& dk, const DNSName& signer, const DNSName signQName, uint16_t signQType, uint32_t signTTL,
  39                      vector<shared_ptr<DNSRecordContent> >& toSign, vector<RRSIGRecordContent>& rrcs)
  40 {
  41   if(toSign.empty())
  42     return -1;
  43   uint32_t startOfWeek = getStartOfWeek();
  44   RRSIGRecordContent rrc;
  45   rrc.d_type=signQType;
  46
  47   rrc.d_labels=signQName.countLabels()-signQName.isWildcard();
  48   rrc.d_originalttl=signTTL;
  49   rrc.d_siginception=startOfWeek - 7*86400; // XXX should come from zone metadata
  50   rrc.d_sigexpire=startOfWeek + 14*86400;
  51   rrc.d_signer = signer;
  52   rrc.d_tag = 0;
  53
  54   DNSSECKeeper::keyset_t keys = dk.getKeys(signer);
  55
  56   for(DNSSECKeeper::keyset_t::value_type& keymeta : keys) {
  57     if(!keymeta.second.active)
  58       continue;
  59
  60     if((signQType == QType::DNSKEY && keymeta.second.keyType == DNSSECKeeper::ZSK) ||
  61        (signQType != QType::DNSKEY && keymeta.second.keyType == DNSSECKeeper::KSK)) {
  62       continue;
  63     }
  64
  65     fillOutRRSIG(keymeta.first, signQName, rrc, toSign);
  66     rrcs.push_back(rrc);
  67   }
  68   return 0;
  69 }
  70
  71 // this is the entrypoint from DNSPacket
  72 void addSignature(DNSSECKeeper& dk, UeberBackend& db, const DNSName& signer, const DNSName signQName, const DNSName& wildcardname, uint16_t signQType,
  73   uint32_t signTTL, DNSResourceRecord::Place signPlace,
  74   vector<shared_ptr<DNSRecordContent> >& toSign, vector<DNSZoneRecord>& outsigned, uint32_t origTTL)
  75 {
  76   //cerr<<"Asked to sign '"<<signQName<<"'|"<<DNSRecordContent::NumberToType(signQType)<<", "<<toSign.size()<<" records\n";
  77   if(toSign.empty())
  78     return;
  79   vector<RRSIGRecordContent> rrcs;
  80   if(dk.isPresigned(signer)) {
  81     //cerr<<"Doing presignatures"<<endl;
  82     dk.getPreRRSIGs(db, signer, signQName, wildcardname, QType(signQType), signPlace, outsigned, origTTL); // does it all
  83   }
  84   else {
  85     if(getRRSIGsForRRSET(dk, signer, wildcardname.countLabels() ? wildcardname : signQName, signQType, signTTL, toSign, rrcs) < 0)  {
  86       // cerr<<"Error signing a record!"<<endl;
  87       return;
  88     }
  89
  90     DNSZoneRecord rr;
  91     rr.dr.d_name=signQName;
  92     rr.dr.d_type=QType::RRSIG;
  93     if(origTTL)
  94       rr.dr.d_ttl=origTTL;
  95     else
  96       rr.dr.d_ttl=signTTL;
  97     rr.auth=false;
  98     rr.dr.d_place = signPlace;
  99     for(RRSIGRecordContent& rrc :  rrcs) {
 100       rr.dr.d_content = std::make_shared<RRSIGRecordContent>(rrc);
 101       outsigned.push_back(rr);
 102     }
 103   }
 104   toSign.clear();
 105 }
 106
 107 static pthread_rwlock_t g_signatures_lock = PTHREAD_RWLOCK_INITIALIZER;
 108 typedef map<pair<string, string>, string> signaturecache_t;
 109 static signaturecache_t g_signatures;
 110 static int g_cacheweekno;
 111
 112 AtomicCounter* g_signatureCount;
 113
 114 uint64_t signatureCacheSize(const std::string& str)
 115 {
 116   ReadLock l(&g_signatures_lock);
 117   return g_signatures.size();
 118 }
 119
 120 void fillOutRRSIG(DNSSECPrivateKey& dpk, const DNSName& signQName, RRSIGRecordContent& rrc, vector<shared_ptr<DNSRecordContent> >& toSign)
 121 {
 122   if(!g_signatureCount)
 123     g_signatureCount = S.getPointer("signatures");
 124
 125   DNSKEYRecordContent drc = dpk.getDNSKEY();
 126   const std::shared_ptr<DNSCryptoKeyEngine> rc = dpk.getKey();
 127   rrc.d_tag = drc.getTag();
 128   rrc.d_algorithm = drc.d_algorithm;
 129
 130   string msg=getMessageForRRSET(signQName, rrc, toSign); // this is what we will hash & sign
 131   pair<string, string> lookup(rc->getPubKeyHash(), pdns_md5sum(msg));  // this hash is a memory saving exercise
 132
 133   bool doCache=1;
 134   if(doCache)
 135   {
 136     ReadLock l(&g_signatures_lock);
 137     signaturecache_t::const_iterator iter = g_signatures.find(lookup);
 138     if(iter != g_signatures.end()) {
 139       rrc.d_signature=iter->second;
 140       return;
 141     }
 142     // else cerr<<"Miss!"<<endl;
 143   }
 144
 145   rrc.d_signature = rc->sign(msg);
 146   (*g_signatureCount)++;
 147   if(doCache) {
 148     /* we add some jitter here so not all your slaves start pruning their caches at the very same millisecond */
 149     int weekno = (time(0) - dns_random(3600)) / (86400*7);  // we just spent milliseconds doing a signature, microsecond more won't kill us
 150     const static int maxcachesize=::arg().asNum("max-signature-cache-entries", INT_MAX);
 151
 152     WriteLock l(&g_signatures_lock);
 153     if(g_cacheweekno < weekno || g_signatures.size() >= (uint) maxcachesize) {  // blunt but effective (C) Habbie, mind04
 154       L<<Logger::Warning<<"Cleared signature cache."<<endl;
 155       g_signatures.clear();
 156       g_cacheweekno = weekno;
 157     }
 158     g_signatures[lookup] = rrc.d_signature;
 159   }
 160 }
 161
 162 static bool rrsigncomp(const DNSZoneRecord& a, const DNSZoneRecord& b)
 163 {
 164   return tie(a.dr.d_place, a.dr.d_type) < tie(b.dr.d_place, b.dr.d_type);
 165 }
 166
 167 static bool getBestAuthFromSet(const set<DNSName>& authSet, const DNSName& name, DNSName& auth)
 168 {
 169   auth.trimToLabels(0);
 170   DNSName sname(name);
 171   do {
 172     if(authSet.find(sname) != authSet.end()) {
 173       auth = sname;
 174       return true;
 175     }
 176   }
 177   while(sname.chopOff());
 178
 179   return false;
 180 }
 181
 182 void addRRSigs(DNSSECKeeper& dk, UeberBackend& db, const set<DNSName>& authSet, vector<DNSZoneRecord>& rrs)
 183 {
 184   stable_sort(rrs.begin(), rrs.end(), rrsigncomp);
 185
 186   DNSName signQName, wildcardQName;
 187   uint16_t signQType=0;
 188   uint32_t signTTL=0;
 189   uint32_t origTTL=0;
 190
 191   DNSResourceRecord::Place signPlace=DNSResourceRecord::ANSWER;
 192   vector<shared_ptr<DNSRecordContent> > toSign;
 193
 194   vector<DNSZoneRecord> signedRecords;
 195   signedRecords.reserve(rrs.size()*1.5);
 196   //  cout<<rrs.size()<<", "<<sizeof(DNSZoneRecord)<<endl;
 197   DNSName signer;
 198   for(auto pos = rrs.cbegin(); pos != rrs.cend(); ++pos) {
 199     if(pos != rrs.cbegin() && (signQType != pos->dr.d_type  || signQName != pos->dr.d_name)) {
 200       if(getBestAuthFromSet(authSet, signQName, signer))
 201         addSignature(dk, db, signer, signQName, wildcardQName, signQType, signTTL, signPlace, toSign, signedRecords, origTTL);
 202     }
 203     signedRecords.push_back(*pos);
 204     signQName= pos->dr.d_name.makeLowerCase();
 205     if(!pos->wildcardname.empty())
 206       wildcardQName = pos->wildcardname.makeLowerCase();
 207     else
 208       wildcardQName.clear();
 209     signQType = pos->dr.d_type;
 210     if(pos->signttl)
 211       signTTL = pos->signttl;
 212     else
 213       signTTL = pos->dr.d_ttl;
 214     origTTL = pos->dr.d_ttl;
 215     signPlace = pos->dr.d_place;
 216     if(pos->auth || pos->dr.d_type == QType::DS) {
 217       toSign.push_back(pos->dr.d_content); // so ponder.. should this be a deep copy perhaps?
 218     }
 219   }
 220   if(getBestAuthFromSet(authSet, signQName, signer))
 221     addSignature(dk, db, signer, signQName, wildcardQName, signQType, signTTL, signPlace, toSign, signedRecords, origTTL);
 222   rrs.swap(signedRecords);
 223 }