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     DNSName getDomain()
 126     {
 127       return d_domain;
 128     }
 129     uint32_t getRefresh()
 130     {
 131       return d_refresh;
 132     }
 133     void dump(FILE * fp) const;
 134
 135     void addClientTrigger(const Netmask& nm, Policy pol);
 136     void addQNameTrigger(const DNSName& nm, Policy pol);
 137     void addNSTrigger(const DNSName& dn, Policy pol);
 138     void addNSIPTrigger(const Netmask& nm, Policy pol);
 139     void addResponseTrigger(const Netmask& nm, Policy pol);
 140
 141     bool rmClientTrigger(const Netmask& nm, Policy pol);
 142     bool rmQNameTrigger(const DNSName& nm, Policy pol);
 143     bool rmNSTrigger(const DNSName& dn, Policy pol);
 144     bool rmNSIPTrigger(const Netmask& nm, Policy pol);
 145     bool rmResponseTrigger(const Netmask& nm, Policy pol);
 146
 147     bool findQNamePolicy(const DNSName& qname, DNSFilterEngine::Policy& pol) const;
 148     bool findNSPolicy(const DNSName& qname, DNSFilterEngine::Policy& pol) const;
 149     bool findNSIPPolicy(const ComboAddress& addr, DNSFilterEngine::Policy& pol) const;
 150     bool findResponsePolicy(const ComboAddress& addr, DNSFilterEngine::Policy& pol) const;
 151     bool findClientPolicy(const ComboAddress& addr, DNSFilterEngine::Policy& pol) const;
 152
 153   private:
 154     static DNSName maskToRPZ(const Netmask& nm);
 155     bool findNamedPolicy(const std::unordered_map<DNSName, DNSFilterEngine::Policy>& polmap, const DNSName& qname, DNSFilterEngine::Policy& pol) const;
 156     void dumpNamedPolicy(FILE* fp, const DNSName& name, const Policy& pol) const;
 157     void dumpAddrPolicy(FILE* fp, const Netmask& nm, const DNSName& name, const Policy& pol) const;
 158
 159     std::unordered_map<DNSName, Policy> d_qpolName;   // QNAME trigger (RPZ)
 160     NetmaskTree<Policy> d_qpolAddr;         // Source address
 161     std::unordered_map<DNSName, Policy> d_propolName; // NSDNAME (RPZ)
 162     NetmaskTree<Policy> d_propolNSAddr;     // NSIP (RPZ)
 163     NetmaskTree<Policy> d_postpolAddr;      // IP trigger (RPZ)
 164     DNSName d_domain;
 165     std::shared_ptr<std::string> d_name;
 166     uint32_t d_serial{0};
 167     uint32_t d_refresh{0};
 168   };
 169
 170   DNSFilterEngine();
 171   void clear()
 172   {
 173     for(auto& z : d_zones) {
 174       z->clear();
 175     }
 176   }
 177   const std::shared_ptr<Zone> getZone(size_t zoneIdx) const
 178   {
 179     std::shared_ptr<Zone> result{nullptr};
 180     if (zoneIdx < d_zones.size()) {
 181       result = d_zones[zoneIdx];
 182     }
 183     return result;
 184   }
 185   const std::shared_ptr<Zone> getZone(const std::string& name) const
 186   {
 187     for (const auto zone : d_zones) {
 188       const auto& zName = zone->getName();
 189       if (zName && *zName == name) {
 190         return zone;
 191       }
 192     }
 193     return nullptr;
 194   }
 195   size_t addZone(std::shared_ptr<Zone> newZone)
 196   {
 197     d_zones.push_back(newZone);
 198     return (d_zones.size() - 1);
 199   }
 200   void setZone(size_t zoneIdx, std::shared_ptr<Zone> newZone)
 201   {
 202     if (newZone) {
 203       assureZones(zoneIdx);
 204       d_zones[zoneIdx] = newZone;
 205     }
 206   }
 207
 208   Policy getQueryPolicy(const DNSName& qname, const ComboAddress& nm, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 209   Policy getProcessingPolicy(const DNSName& qname, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 210   Policy getProcessingPolicy(const ComboAddress& address, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 211   Policy getPostPolicy(const vector<DNSRecord>& records, const std::unordered_map<std::string,bool>& discardedPolicies) const;
 212
 213   size_t size() const {
 214     return d_zones.size();
 215   }
 216 private:
 217   void assureZones(size_t zone);
 218   vector<std::shared_ptr<Zone>> d_zones;
 219 };