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     PolicyKind d_kind;
  85     std::shared_ptr<DNSRecordContent> d_custom;
  86     std::shared_ptr<std::string> d_name;
  87     PolicyKind d_kind;
  88     PolicyType d_type;
  89     int32_t d_ttl;
  90   };
  91
  92   class Zone {
  93   public:
  94     void clear()
  95     {
  96       d_qpolAddr.clear();
  97       d_postpolAddr.clear();
  98       d_propolName.clear();
  99       d_propolNSAddr.clear();
 100       d_qpolName.clear();
 101     }
 102     void reserve(size_t entriesCount)
 103     {
 104       d_qpolName.reserve(entriesCount);
 105     }
 106     void setName(const std::string& name)
 107     {
 108       d_name = std::make_shared<std::string>(name);
 109     }
 110     void setDomain(const DNSName& domain)
 111     {
 112       d_domain = domain;
 113     }
 114     void setSerial(uint32_t serial)
 115     {
 116       d_serial = serial;
 117     }
 118     void setRefresh(uint32_t refresh)
 119     {
 120       d_refresh = refresh;
 121     }
 122     const std::shared_ptr<std::string> getName() const
 123     {
 124       return d_name;
 125     }
 126     void dump(FILE * fp) const;
 127
 128     void addClientTrigger(const Netmask& nm, Policy pol);
 129     void addQNameTrigger(const DNSName& nm, Policy pol);
 130     void addNSTrigger(const DNSName& dn, Policy pol);
 131     void addNSIPTrigger(const Netmask& nm, Policy pol);
 132     void addResponseTrigger(const Netmask& nm, Policy pol);
 133
 134     bool rmClientTrigger(const Netmask& nm, Policy pol);
 135     bool rmQNameTrigger(const DNSName& nm, Policy pol);
 136     bool rmNSTrigger(const DNSName& dn, Policy pol);
 137     bool rmNSIPTrigger(const Netmask& nm, Policy pol);
 138     bool rmResponseTrigger(const Netmask& nm, Policy pol);
 139
 140     bool findQNamePolicy(const DNSName& qname, DNSFilterEngine::Policy& pol) const;
 141     bool findNSPolicy(const DNSName& qname, DNSFilterEngine::Policy& pol) const;
 142     bool findNSIPPolicy(const ComboAddress& addr, DNSFilterEngine::Policy& pol) const;
 143     bool findResponsePolicy(const ComboAddress& addr, DNSFilterEngine::Policy& pol) const;
 144     bool findClientPolicy(const ComboAddress& addr, DNSFilterEngine::Policy& pol) const;
 145
 146   private:
 147     static DNSName maskToRPZ(const Netmask& nm);
 148     bool findNamedPolicy(const std::unordered_map<DNSName, DNSFilterEngine::Policy>& polmap, const DNSName& qname, DNSFilterEngine::Policy& pol) const;
 149     void dumpNamedPolicy(FILE* fp, const DNSName& name, const Policy& pol) const;
 150     void dumpAddrPolicy(FILE* fp, const Netmask& nm, const DNSName& name, const Policy& pol) const;
 151
 152     std::unordered_map<DNSName, Policy> d_qpolName;   // QNAME trigger (RPZ)
 153     NetmaskTree<Policy> d_qpolAddr;         // Source address
 154     std::unordered_map<DNSName, Policy> d_propolName; // NSDNAME (RPZ)
 155     NetmaskTree<Policy> d_propolNSAddr;     // NSIP (RPZ)
 156     NetmaskTree<Policy> d_postpolAddr;      // IP trigger (RPZ)
 157     DNSName d_domain;
 158     std::shared_ptr<std::string> d_name;
 159     uint32_t d_serial{0};
 160     uint32_t d_refresh{0};
 161   };
 162
 163   DNSFilterEngine();
 164   void clear()
 165   {
 166     for(auto& z : d_zones) {
 167       z->clear();
 168     }
 169   }
 170   const std::shared_ptr<Zone> getZone(size_t zoneIdx) const
 171   {
 172     std::shared_ptr<Zone> result{nullptr};
 173     if (zoneIdx < d_zones.size()) {
 174       result = d_zones[zoneIdx];
 175     }
 176     return result;
 177   }
 178   const std::shared_ptr<Zone> getZone(const std::string& name) const
 179   {
 180     for (const auto zone : d_zones) {
 181       const auto& zName = zone->getName();
 182       if (zName && *zName == name) {
 183         return zone;
 184       }
 185     }
 186     return nullptr;
 187   }
 188   size_t addZone(std::shared_ptr<Zone> newZone)
 189   {
 190     d_zones.push_back(newZone);
 191     return (d_zones.size() - 1);
 192   }
 193   void setZone(size_t zoneIdx, std::shared_ptr<Zone> newZone)
 194   {
 195     if (newZone) {
 196       assureZones(zoneIdx);
 197       d_zones[zoneIdx] = newZone;
 198     }
 199   }
 200
 201   Policy getQueryPolicy(const DNSName& qname, const ComboAddress& nm, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 202   Policy getProcessingPolicy(const DNSName& qname, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 203   Policy getProcessingPolicy(const ComboAddress& address, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 204   Policy getPostPolicy(const vector<DNSRecord>& records, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 205
 206   size_t size() const {
 207     return d_zones.size();
 208   }
 209 private:
 210   void assureZones(size_t zone);
 211   vector<std::shared_ptr<Zone>> d_zones;
 212 };