pdns/filterpo.hh

   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 #pragma once
  23 #include "iputils.hh"
  24 #include "dns.hh"
  25 #include "dnsname.hh"
  26 #include "dnsparser.hh"
  27 #include <map>
  28 #include <unordered_map>
  29
  30 /* This class implements a filtering policy that is able to fully implement RPZ, but is not bound to it.
  31    In other words, it is generic enough to support RPZ, but could get its data from other places.
  32
  33
  34    We know the following actions:
  35
  36    No action - just pass it on
  37    Drop - drop a query, no response
  38    NXDOMAIN - fake up an NXDOMAIN for the query
  39    NODATA - just return no data for this qtype
  40    Truncate - set TC bit
  41    Modified - "we fake an answer for you"
  42
  43    These actions can be caused by the following triggers:
  44
  45    qname - the query name
  46    client-ip - the IP address of the requestor
  47    response-ip - an IP address in the response
  48    ns-name - the name of a server used in the delegation
  49    ns-ip - the IP address of a server used in the delegation
  50
  51    This means we get several hook points:
  52    1) when the query comes in: qname & client-ip
  53    2) during processing: ns-name & ns-ip
  54    3) after processing: response-ip
  55
  56    Triggers meanwhile can apply to:
  57    Verbatim domain names
  58    Wildcard versions (*.domain.com does NOT match domain.com)
  59    Netmasks (IPv4 and IPv6)
  60    Finally, triggers are grouped in different zones. The "first" zone that has a match
  61    is consulted. Then within that zone, rules again have precedences.
  62 */
  63
  64
  65 class DNSFilterEngine
  66 {
  67 public:
  68   enum class PolicyKind { NoAction, Drop, NXDOMAIN, NODATA, Truncate, Custom};
  69   enum class PolicyType { None, QName, ClientIP, ResponseIP, NSDName, NSIP };
  70
  71   struct Policy
  72   {
  73     Policy(): d_custom(nullptr), d_name(nullptr), d_kind(PolicyKind::NoAction), d_type(PolicyType::None), d_ttl(0)
  74     {
  75     }
  76     bool operator==(const Policy& rhs) const
  77     {
  78       return d_kind == rhs.d_kind; // XXX check d_custom too!
  79     }
  80     std::string getKindToString() const;
  81     DNSRecord getCustomRecord(const DNSName& qname) const;
  82     DNSRecord getRecord(const DNSName& qname) const;
  83
  84     std::shared_ptr<DNSRecordContent> d_custom;
  85     std::shared_ptr<std::string> d_name;
  86     PolicyKind d_kind;
  87     PolicyType d_type;
  88     int32_t d_ttl;
  89   };
  90
  91   class Zone {
  92   public:
  93     void clear()
  94     {
  95       d_qpolAddr.clear();
  96       d_postpolAddr.clear();
  97       d_propolName.clear();
  98       d_propolNSAddr.clear();
  99       d_qpolName.clear();
 100     }
 101     void reserve(size_t entriesCount)
 102     {
 103       d_qpolName.reserve(entriesCount);
 104     }
 105     void setName(const std::string& name)
 106     {
 107       d_name = std::make_shared<std::string>(name);
 108     }
 109     void setDomain(const DNSName& domain)
 110     {
 111       d_domain = domain;
 112     }
 113     void setSerial(uint32_t serial)
 114     {
 115       d_serial = serial;
 116     }
 117     void setRefresh(uint32_t refresh)
 118     {
 119       d_refresh = refresh;
 120     }
 121     const std::shared_ptr<std::string> getName() const
 122     {
 123       return d_name;
 124     }
 125     void dump(FILE * fp) const;
 126
 127     void addClientTrigger(const Netmask& nm, Policy pol);
 128     void addQNameTrigger(const DNSName& nm, Policy pol);
 129     void addNSTrigger(const DNSName& dn, Policy pol);
 130     void addNSIPTrigger(const Netmask& nm, Policy pol);
 131     void addResponseTrigger(const Netmask& nm, Policy pol);
 132
 133     bool rmClientTrigger(const Netmask& nm, Policy pol);
 134     bool rmQNameTrigger(const DNSName& nm, Policy pol);
 135     bool rmNSTrigger(const DNSName& dn, Policy pol);
 136     bool rmNSIPTrigger(const Netmask& nm, Policy pol);
 137     bool rmResponseTrigger(const Netmask& nm, Policy pol);
 138
 139     bool findQNamePolicy(const DNSName& qname, DNSFilterEngine::Policy& pol) const;
 140     bool findNSPolicy(const DNSName& qname, DNSFilterEngine::Policy& pol) const;
 141     bool findNSIPPolicy(const ComboAddress& addr, DNSFilterEngine::Policy& pol) const;
 142     bool findResponsePolicy(const ComboAddress& addr, DNSFilterEngine::Policy& pol) const;
 143     bool findClientPolicy(const ComboAddress& addr, DNSFilterEngine::Policy& pol) const;
 144
 145   private:
 146     static DNSName maskToRPZ(const Netmask& nm);
 147     bool findNamedPolicy(const std::unordered_map<DNSName, DNSFilterEngine::Policy>& polmap, const DNSName& qname, DNSFilterEngine::Policy& pol) const;
 148     void dumpNamedPolicy(FILE* fp, const DNSName& name, const Policy& pol) const;
 149     void dumpAddrPolicy(FILE* fp, const Netmask& nm, const DNSName& name, const Policy& pol) const;
 150
 151     std::unordered_map<DNSName, Policy> d_qpolName;   // QNAME trigger (RPZ)
 152     NetmaskTree<Policy> d_qpolAddr;         // Source address
 153     std::unordered_map<DNSName, Policy> d_propolName; // NSDNAME (RPZ)
 154     NetmaskTree<Policy> d_propolNSAddr;     // NSIP (RPZ)
 155     NetmaskTree<Policy> d_postpolAddr;      // IP trigger (RPZ)
 156     DNSName d_domain;
 157     std::shared_ptr<std::string> d_name;
 158     uint32_t d_serial{0};
 159     uint32_t d_refresh{0};
 160   };
 161
 162   DNSFilterEngine();
 163   void clear()
 164   {
 165     for(auto& z : d_zones) {
 166       z->clear();
 167     }
 168   }
 169   const std::shared_ptr<Zone> getZone(size_t zoneIdx) const
 170   {
 171     std::shared_ptr<Zone> result{nullptr};
 172     if (zoneIdx < d_zones.size()) {
 173       result = d_zones[zoneIdx];
 174     }
 175     return result;
 176   }
 177   const std::shared_ptr<Zone> getZone(const std::string& name) const
 178   {
 179     for (const auto zone : d_zones) {
 180       const auto& zName = zone->getName();
 181       if (zName && *zName == name) {
 182         return zone;
 183       }
 184     }
 185     return nullptr;
 186   }
 187   size_t addZone(std::shared_ptr<Zone> newZone)
 188   {
 189     d_zones.push_back(newZone);
 190     return (d_zones.size() - 1);
 191   }
 192   void setZone(size_t zoneIdx, std::shared_ptr<Zone> newZone)
 193   {
 194     if (newZone) {
 195       assureZones(zoneIdx);
 196       d_zones[zoneIdx] = newZone;
 197     }
 198   }
 199
 200   Policy getQueryPolicy(const DNSName& qname, const ComboAddress& nm, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 201   Policy getProcessingPolicy(const DNSName& qname, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 202   Policy getProcessingPolicy(const ComboAddress& address, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 203   Policy getPostPolicy(const vector<DNSRecord>& records, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 204
 205   size_t size() const {
 206     return d_zones.size();
 207   }
 208 private:
 209   void assureZones(size_t zone);
 210   vector<std::shared_ptr<Zone>> d_zones;
 211 };