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 static pthread_rwlock_t g_signatures_lock = PTHREAD_RWLOCK_INITIALIZER;
  37 typedef map<pair<string, string>, string> signaturecache_t;
  38 static signaturecache_t g_signatures;
  39 static int g_cacheweekno;
  40
  41 AtomicCounter* g_signatureCount;
  42
  43 static void fillOutRRSIG(DNSSECPrivateKey& dpk, const DNSName& signQName, RRSIGRecordContent& rrc, vector<shared_ptr<DNSRecordContent> >& toSign)
  44 {
  45   if(!g_signatureCount)
  46     g_signatureCount = S.getPointer("signatures");
  47
  48   DNSKEYRecordContent drc = dpk.getDNSKEY();
  49   const std::shared_ptr<DNSCryptoKeyEngine> rc = dpk.getKey();
  50   rrc.d_tag = drc.getTag();
  51   rrc.d_algorithm = drc.d_algorithm;
  52
  53   string msg=getMessageForRRSET(signQName, rrc, toSign); // this is what we will hash & sign
  54   pair<string, string> lookup(rc->getPubKeyHash(), pdns_md5sum(msg));  // this hash is a memory saving exercise
  55
  56   bool doCache=1;
  57   if(doCache)
  58   {
  59     ReadLock l(&g_signatures_lock);
  60     signaturecache_t::const_iterator iter = g_signatures.find(lookup);
  61     if(iter != g_signatures.end()) {
  62       rrc.d_signature=iter->second;
  63       return;
  64     }
  65     // else cerr<<"Miss!"<<endl;
  66   }
  67
  68   rrc.d_signature = rc->sign(msg);
  69   (*g_signatureCount)++;
  70   if(doCache) {
  71     /* we add some jitter here so not all your slaves start pruning their caches at the very same millisecond */
  72     int weekno = (time(0) - dns_random(3600)) / (86400*7);  // we just spent milliseconds doing a signature, microsecond more won't kill us
  73     const static int maxcachesize=::arg().asNum("max-signature-cache-entries", INT_MAX);
  74
  75     WriteLock l(&g_signatures_lock);
  76     if(g_cacheweekno < weekno || g_signatures.size() >= (uint) maxcachesize) {  // blunt but effective (C) Habbie, mind04
  77       L<<Logger::Warning<<"Cleared signature cache."<<endl;
  78       g_signatures.clear();
  79       g_cacheweekno = weekno;
  80     }
  81     g_signatures[lookup] = rrc.d_signature;
  82   }
  83 }
  84
  85 /* this is where the RRSIGs begin, keys are retrieved,
  86    but the actual signing happens in fillOutRRSIG */
  87 static int getRRSIGsForRRSET(DNSSECKeeper& dk, const DNSName& signer, const DNSName signQName, uint16_t signQType, uint32_t signTTL,
  88                              vector<shared_ptr<DNSRecordContent> >& toSign, vector<RRSIGRecordContent>& rrcs)
  89 {
  90   if(toSign.empty())
  91     return -1;
  92   uint32_t startOfWeek = getStartOfWeek();
  93   RRSIGRecordContent rrc;
  94   rrc.d_type=signQType;
  95
  96   rrc.d_labels=signQName.countLabels()-signQName.isWildcard();
  97   rrc.d_originalttl=signTTL;
  98   rrc.d_siginception=startOfWeek - 7*86400; // XXX should come from zone metadata
  99   rrc.d_sigexpire=startOfWeek + 14*86400;
 100   rrc.d_signer = signer;
 101   rrc.d_tag = 0;
 102
 103   DNSSECKeeper::keyset_t keys = dk.getKeys(signer);
 104
 105   for(DNSSECKeeper::keyset_t::value_type& keymeta : keys) {
 106     if(!keymeta.second.active)
 107       continue;
 108
 109     if((signQType == QType::DNSKEY && keymeta.second.keyType == DNSSECKeeper::ZSK) ||
 110        (signQType != QType::DNSKEY && keymeta.second.keyType == DNSSECKeeper::KSK)) {
 111       continue;
 112     }
 113
 114     fillOutRRSIG(keymeta.first, signQName, rrc, toSign);
 115     rrcs.push_back(rrc);
 116   }
 117   return 0;
 118 }
 119
 120 // this is the entrypoint from DNSPacket
 121 static void addSignature(DNSSECKeeper& dk, UeberBackend& db, const DNSName& signer, const DNSName signQName, const DNSName& wildcardname, uint16_t signQType,
 122                          uint32_t signTTL, DNSResourceRecord::Place signPlace,
 123                          vector<shared_ptr<DNSRecordContent> >& toSign, vector<DNSZoneRecord>& outsigned, uint32_t origTTL)
 124 {
 125   //cerr<<"Asked to sign '"<<signQName<<"'|"<<DNSRecordContent::NumberToType(signQType)<<", "<<toSign.size()<<" records\n";
 126   if(toSign.empty())
 127     return;
 128   vector<RRSIGRecordContent> rrcs;
 129   if(dk.isPresigned(signer)) {
 130     //cerr<<"Doing presignatures"<<endl;
 131     dk.getPreRRSIGs(db, signer, signQName, wildcardname, QType(signQType), signPlace, outsigned, origTTL); // does it all
 132   }
 133   else {
 134     if(getRRSIGsForRRSET(dk, signer, wildcardname.countLabels() ? wildcardname : signQName, signQType, signTTL, toSign, rrcs) < 0)  {
 135       // cerr<<"Error signing a record!"<<endl;
 136       return;
 137     }
 138
 139     DNSZoneRecord rr;
 140     rr.dr.d_name=signQName;
 141     rr.dr.d_type=QType::RRSIG;
 142     if(origTTL)
 143       rr.dr.d_ttl=origTTL;
 144     else
 145       rr.dr.d_ttl=signTTL;
 146     rr.auth=false;
 147     rr.dr.d_place = signPlace;
 148     for(RRSIGRecordContent& rrc :  rrcs) {
 149       rr.dr.d_content = std::make_shared<RRSIGRecordContent>(rrc);
 150       outsigned.push_back(rr);
 151     }
 152   }
 153   toSign.clear();
 154 }
 155
 156 uint64_t signatureCacheSize(const std::string& str)
 157 {
 158   ReadLock l(&g_signatures_lock);
 159   return g_signatures.size();
 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 }